Jeevanu Times Dec 2010

8/19/2019 Jeevanu Times Dec 2010

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Jeevanu Times

Newsletter I MM Delhi Chapter

Volume: 10 Number: 3 An official publication of Indian Association of Medical Microbiologists – Delhi Chapter


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Editorial Committee

Chief Editor:

Dr. Raman SardanaSenior Consultant and Additional Director Medical ServicesIndraprastha Apollo Hospitals, New [email protected]

Assistant Editors:

Dr. Vikas ManchandaChacha Nehru Bal ChikitsalayaGeeta Colony, [email protected]

Dr. Reetika DawarIndraprastha Apollo Hospitals,

New [email protected]

Image on cover page: Apoptosis


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Contents

From the Editor’s Desk … .............................................................................................................................................................................. 3

Signaling and Molecular Mechanisms of Apoptotic Cell Death and Relationship to Human Diseases .... 4

Goyal Ritika, Department of Microbiology, UCMS & GTBH, Dilshad Garden, Delhi – 110091.

Invasive fungal sinusitis by Scopulariopsis brevicularis - A Case Report . .................................................................... 11

Arora S, Dawar R, Sardana R, Indraprastha Apollo Hospitals, Sarita Vihar, Delhi-Mathura Road, New Delhi-110076.

What is your diagnosis? ............................................................................................................................................................................... 12

Aggarwal S, Manchanda V, Clinical Microbiology and Infectious Diseases, Chacha Nehru Bal Chikitsalaya, Geeta

Colony, Delhi.

Answers to the Crossword No. 1003 ................................................................................................................................................... 14

pH measurement, indicators and buffers ........................................................................................................................................ 15

Batra P, Saxena S, Dutta R. Department of Microbiology, Lady Hardinge Medical College, New Delhi

Candida — An Emerging Pathogen ........................................................................................................................................................ 18

Bhagat S, Rajani M, Saxena S, Dutta R. Department of Microbiology, Lady Hardinge Medical College, Delhi ............. 18

Crossword puzzle no. 1003 ....................................................................................................................................................................... 22


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Signaling and Molecular Mechanisms of Apoptotic Cell Deathand Relationship to Human Diseases

Goyal RitikaDepartment of Microbiology, UCMS & GTBH, Dilshad Garden, Delhi - 110091

IntroductionApoptosis is a highly organized, evolutionary conserved,genetically regulated pathway for maintaininghomeostasis in multicellular organisms. The term wascoined by Kerr, Wyllie and Curie. This coordinated andenergy-dependent process involves activation of group ofcyste ine proteases called ―caspases‖ and a complexcascade of events that link the initiating stimuli to the

final demise of the cell. The cell death appears to be fixeddevelopmentally and is thus programmed and hence alsocalled Programmed Cell Death.Apoptosis can be either physiologic or pathological.Physiological apoptosis occurs during development,ageing and as a homeostatic mechanism to maintain cell

populations in tissues. Remodeling in adult, such as thefollicular atresia of postovulatory follicle and post-weaning mammary gland involution is another suchexample. It is most common form of death in cells of theimmune system and regulates lymphocyte maturation,receptor repertoire selection and homeostasis.Pathologic apoptosis occurs in diseases assoc. with eitherincreased or decreased apoptosis. (Table1 and Table 2)

Table.1

Table.2

Molecular mechanisms of apoptosis

Morphological and biochemical features:An apoptotic cell is small in size with dense eosinophiliccytoplasm, pyknotic nucleus and tightly packed

organelles. Extensive plasma membrane blebbing occursand separation of cell fragments into apoptotic bodies, process called ―budding.‖ These bodies are subsequently phagocytosed by macrophages and degraded within phagolysosomes. Since apoptotic cells do not releasetheir cellular constituents into the surrounding interstitialtissue and are quickly phagocytosed there is essentiallyno inflammatory reaction associated neither with the

process of apoptosis nor with the removal of apoptoticcells. Apoptosis is frequently confused with necrosiswhich is an uncontrolled, energy-independent mode of

passive process leading to cell swelling, cell membranefragmentation and inflammation. (Fig.1).


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Initiation Pathways:There are three pathways which ultimately lead to celldeath, namely, Extrinsic or Death Receptor Pathway,Intrinsic or Mitochondrial Pathway and Perforin-Granzyme Dependent Killing of the Cell.

• Extrinsic or Death Receptor Pathway (Fig.2,3)is triggered by absence of certain growth

factors/ hormones/ cytokines, radiation, toxins,hypoxia and hyperthermia. TNF-L/FasL bind toreceptors TNFR-1/Fas, which further bind anadapter protein, Tradd, via its homologous DD.DD of Tradd binds to DD of the adapter proteinFadd. The Fadd protein contains two proteins aDD and a DED. Fas employs its DED to bindDED-containing procaspases 8/10 which inturn activate execution caspases 3,6,7 leadingto formation of Death-inducing signalingcomplex (DISC) and hence apoptosis. Proteinsnamely c-FLIP and Toso help regulate this

pathway.• Pro-apoptosis signals originating in the nucleus,

mitochondria, the endoplasmic reticulum,lysosomes and the golgi bodies trigger theIntrinsic or Mitochondrial Pathway (Fig.4, 5). Change in the inner mitochondrial membraneresults in opening of the mitochondrial

permeability transition (MPT) pore, loss of themitochondrial transmembrane potential andrelease of Cytochrome c, smac/DIABLO and

Htra2/omi and AIF, Endonuclease G and CAD.In the presence of cytosolic dATP or ATP,apoptotic protease activation factor-1 (Apaf-1)oligomerizes. Oligomerized Apaf-1 togetherwith cytosolic procaspase-9, dATP andcytochrome c result in the formation of amassive complex known as apoptosome.

Activated caspase-9 can in turn activate procaspase-3, 7.

• AIF, Endonuclease G and CAD translocate tothe nucleus where it cleaves nuclear chromatinto produce DNA fragments. Apoptosisregulation of this pathway is brought about byBcl-2 family of proteins, Noxa and Puma.

• Cytotoxic T-lymphocytes (CTLs) and naturalkiller (NK) cells trigger apoptosis ofsusceptible target cells either through a Fasligand- or perforin/granzyme B-dependent

pathway. This pathway operates mainly in viraldefense and immune surveillance againstcancer. Secretion of the transmembrane pore-

forming molecule perforin results in release ofcytoplasmic granules through the pore into thetarget cell. The serine proteases granzyme Aand granzyme B are the most importantcomponent within the granules.Granzymesactivate procaspase-10 and cleave factors likeICAD (inhibitor of caspase activated Dnase).

•

Figure 1. Distinguishing Apoptosis from Necrosis . Apoptotic cells exhibit several biochemical modifications such ascytoskeletal protein cleavage(caspases), protein cross-linking(transglutaminase) and DNA breakdown(endonucleases).


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Figure 2. Extrinsic or Death Receptor Pathway


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Figure 3. Extrinsic or Death Receptor Pathway

Figure 4. Intrinsic or Mitochondrial Pathway

Figure 5. Intrinsic or Mitochondrial Pathway: Apoptosome formation and activation

Execution PathwayIt is brought about by caspases which are aspartate-specific cysteine proteases and members of theinterleukin- 1β-converting enzyme family. Fourteencaspases have been identified so far. Members of caspasefamily include Upstream or initiator caspases (includecaspases 2, 8, 9 and 10), Downstream or effector orexecution caspases (include caspases 3, 6, 7) andcaspases involved in cytokine activation and

inflammation (include caspases 1, 4, 5, 11, 12, 13 and14).

Apoptosis activator caspases activate other downstreamapoptosis executioner caspases, which can subsequentlycleave distinct cellular proteins such as PARP,cytokeratins, lamin, plasma membrane cytoskeletal

protein alpha-fodrin and nuclear protein NuMa, leadingto the characteristic morphological changes.

Phagocytic RecognitionPhospholipid asymmetry and externalization of normal

inward-facing phosphatidylserine (PS) on the surface ofapoptotic cells facilitates noninflammatory phagocytic


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recognition, allowing for their early uptake and disposal.This process of early and efficient uptake with no releaseof cellular constituents, results in essentially noinflammatory response. Annexin I, a PS binding proteinis recruited from the cytosol to the plasma membraneduring apoptosis, and is required for efficient uptake ofapoptotic cells. In addition macrophages after ingestion

of apoptotic bodies, secrete anti-inflammatory cytokinesthat serve to further down regulate the inflammatoryresponse.

Apoptosis regulationProtein domains associated with apoptosis regulationinclude Caspase (catalytic) Domains, BIR Domains(IAPs), Bcl-2 Homology (BH) Domains, Death Domains(DDs), Death Effector Domains (DEDs) and Caspase-Associated Recruitment Domains (CARDs). Alterationsin the expression of which is associated with diseases.

Apoptosis in human diseasesApoptosis dysregulation contributes to nearly half of all

human diseases. (Fig.6).

1. Autoimmune lymphoproliferative syndrome(ALPS)

Insufficient apoptosis of T cells results in multipleautoimmune diseases. Some of the common diseasesof ALPS include hemolytic anemia, immune-mediated thrombocytopenia, SLE and autoimmuneneutropenia. Mutation in the death domain of theFas receptor or mutation in Fas ligand or mutation incaspase-10, reducing its activity.

Organ-specific diseases are characterized by a T-lymphocyte-mediated attack on specific cell types,including• the ß-cells of the islets of Langerhans in IDDM

• oligodendrocytes in the brain in multiplesclerosis and

• thyrocytes in Hashimoto‘s thyroiditis.

2. Cancer Suppression of apoptosis:

• Overexpression of anti-apoptotic proteins suchas bcl-2 (human B cell lymphoma) or

• Down-regulation/ mutation of pro-apoptotic proteins such as bax.

• Survivin, a member of IAP family is found to be expressed in most human cancers.

• Evasion of immune surveillance.• Downregulation of the Fas receptor on

tumor cells• Expression of nonfunctioning Fas

receptor,• Secretion of high levels of a soluble form

of the Fas receptor that sequester the Fasligand

• Fas ligand-mediated ―counterattack‖ ofactivated tumor infiltrating lymphocytes thatresults in apoptotic depletion.

• p53 (tumor suppressor gene) is mutated in over50% of all human cancers.

• Apoptosis stimulating protein of p53 (ASPP)enhance p53 – induced apoptosis.

• An inhibitory member of ASPP family (iASPP)has been found which an inhibitor of p53 is andit is upregulated in human breast carcinomas.

• Cannabalism: Cancer cells can engulf apoptotic bodies and reutilize the salvaged DNA,suggesting horizontal transfer of geneticinformation between somatic cells ( Prostatecancer cells)

Figure 6. Apoptosis in human diseases


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3. Infectious diseases: viral infections Viruses inhibit apoptosis:

• Effective adenoviral infection depends on E1B19K protein, a viral homologue of theantiapoptotic protein Bcl-2.

• Another adenovirus protein, termed RID(receptor internalization and degradation),mediates internalization and subsequentlysosomal destruction of cell surface Fas,which may allow cells to resist Fas mediateddeath and promote the survival of the virus.

• Numerous herpesviruses contain FLIPs(FLICE-inhibitory proteins) which interact withthe Fas-associated adaptor protein,FADD. Thisinteraction inhibits signaling events inducedupon ligation of Fas or the TNF receptor bytheir respective ligands.

• However, Ebola virus infection is associatedwith massive apoptosis for the purpose of

facilitating viral release towards the end of theviral replicative cycle, and thereby succeed to promote viral infectivity and pathogenesis.

4. Infectious diseases: bacterial infections Bacteria as triggers of apoptosis:

• Macrophages undergo apoptosis upon infectionwith Salmonella typhimurium, Shigella flexneriand Yersinia pseudotuberculosis.

• Ipa-b, a bacterial invasin of S. flexneri , inducesapoptosis by binding directly to caspase 1.Since caspase1 is also a proinflammatorymolecule,this binding also initiateinflammation.

• I/C Chlamydia trachomatis possess anantiapoptosis mechanism, namely the blockadeof mitochondrial cytochrome c release.

5. Neurodegenerative diseases Huntington‘s disease gene product, huntingtin(polyglutamine repeat ), is a substrate forcaspase 3. Cytosolic aggregates of

polyglutamine repeat proteins recruit procaspase 8, resulting in the activation ofcaspase – 8.Amyotrophic lateral sclerosis (ALS): mutationsin the gene encoding the cytosolic Cu/Zn

superoxide dismutase gene. These SOD-1mutations can activate caspase-1 and caspase-3and might increase free radical generation,leading to motor neuron apoptosis.Alzheimer‘s disease:

• Mutations in proteins such as APP (amyloid precursor protein) and presenilins.

• Presenilins are thought to be involved in the processing of APP to amyloid β.

• Deposition of amyloid β in extracellulardeposits known as plaques which is neurotoxic.Amyloid β is thought to induce apoptosis bycausing oxidative stress or by triggeringincreased Fas ligand expressions in neurons and

glia.

6. Atherosclerosis and stroke • Apoptotic death of endothelial cells and smooth

muscle cells• Pro-atherosclerotic factors such as angiotensin

II, oxidized LDL, ROS and inflammatorycytokines all induce apoptosis in endothelialcells, whereas known protective factors such asestrogen and nitric oxide prevent apoptosis inthese cells.

• Overexpression of BAX (pro apoptotic)

7. Transplantation • Immune-privileged sites in the body, such as

the testis and the anterior chamber of the eye,enjoy prolonged survival of allogeneic orxenogeneic tissue grafts.

• Immune privilege was originally perceived as a

passive process relying on physical barriers andisolation, recent data support immune privilegeas an active phenomenon. Specifically, anumber of studies have indicated a role for Fasin maintaining the immune-privileged state

Assays for apoptosis

Apoptosis assays, based on methodology,areclassified into six major groups:

1. Cytomorphological Alterations: Hematoxylinand Eosin-stained tissue sections with lightmicroscopy , Semi-ultrathin sections stainedwith toluidine blue or methylene blue, TEM

2. DNA Fragmentation: DNA laddering technique, TUNEL (Terminal dUTP Nick End-Labeling)method

3. Detection of Caspases, Cleaved substrates,Regulators and Inhibitors:Immunohistochemistry, Immunoprecipitation,Western blot, Apoptosis PCR

4. Membrane Alterations: FITC-labeled AnnexinV

5. Detection of apoptosis in Whole Mounts :Acridine orange (AO), Nile blue sulfate (NBS),and neutral red(NR) , Lyso-Tracker Red

6. Mitochondrial Assays: Mitochondrial permeability transition (MPT), depolarizationof the inner mitochondrial membrane, Ca2+

fluxes, mitochondrial redox status, and ROS,Laser Scanning Confocal Microscope.

Modulation of apoptosis for therapy

Anti-TNF antibody Adalimumab: phase IIIclinical trials for rheumatoid arthritis.

CD95/CD95L has been implicated in stroke,multiple sclerosis, graft-versus-host disease andothers and thus are an appealing target fortherapeutic intervention.

TRAIL agonists have reached clinical phase forcombating cancer and other apoptosis related

disorders, either as a single agent or with


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standard therapy. A synergistic effect was seenwith TRAIL and 5-FU.

Antisense approach:• Clinical trials are also ongoing for

Non- Hodgkins lymphoma, breastcancer, leukemia, small cell lungcancer along with antisense Bcl-2/cyclophosphamide.

• Antisense survivin is being studiedfor osteocarcinoma, lungadenocarcinoma, etc.

IAP antagonists : Antisense targeting of XIAPhas been shown to sensitize a variety of tumorcell lines to radio or chemotherapy for solidtumors.

Caspase inhibitors : represent modified tetra or tri peptide Pseudosubstrates. eg. x-VAD fmk, VX-740(caspase-1 inhibitor),VX-756,VX799 , IND-1965,MX-1013 (inhibits several caspases), MX 1122(inhibits caspase-3) . Proven in animal models forvarious disease conditions associated with

inappropriate apoptosis, such as heart and liverinjury by alcohol, or hepatitis B and C infection,lung injury, sepsis, brain ischemia, acute myocardialinfarction, nephrotoxic nephritis and in arthritis. Activation of cellular caspases by small cell

permeable drugs might provide a more efficientvenue to target cancer cells. They can directly

bind near the active site of caspase-3 leading toits acute activation, already in clinical use asantithrombotic drugs.

Overexpression of chimeric immunocaspase-3or immunocaspase-6 gene: Caspase-3 fusedwith antibodies directed towards tumor-specific

proteins seems to provide selective induction ofapoptosis in tumor cell.

Restoration of normal function of mutant p53: interfering with the binding of its negativeregulator Mdm2 either by employing peptidesor synthetic drugs.

References:1. Caspase Family Proteases and Apoptosis. Ting-

Jun Fan, Li-Hui Han, Ri-Shan Cong and JinLiang. Acta Biochimica et Biophysica Sinica2005, 37(11): 719 – 727

2. Mechanisms of Apoptosis. John C. Reed.American Journal of Pathology, Vol. 157, No.

5, November 20003. Caspases: the executioners of apoptosis. GeraldM. Cohen. Biochem. J. (1997) 326, 1-16

4. Apoptosis: a basic biological phenomenon withwide-ranging implications in human disease. B.Fadeel, S. Orrenius. Journal of InternalMedicine 2005; 258: 479 – 517.

ERRATUM

Authors’s name in an article titled "CLASSIFICATION STRATEGIES IN BACTERIOLOGY" in JeevanuTimes Volume: 10, Number: 2 should read as GAURAV DHAKA instead of Gaurav Deka.


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Invasive fungal sinusitis by Scopulariopsis brevicularis - ACase Report.

Arora S, Dawar R, Sardana RIndraprastha Apollo Hospitals, Sarita Vihar, Delhi-Mathura Road, New Delhi-110076

Scopulariopsis brevicularis a common soil saprophyte;rarely has been reported as a cause of deep fungalinfection. However in the last two decades the fungushas been reported from fungal ball in preformed cavities,keratitis, post traumatic endopthalmitis, disseminatedskin lesions in AIDS patients, granulomatoussubcutaneous infections, invasive hyalohypomycosis ,

pneumonia in leukemia patients, endocarditis related tovalvoplasty or prosthetic valves and fatal disseminatedinfection after bone marrow transplantation 1. We are

presenting a case of a 11 year female child presented inthe ENT out patient department with a history of nasalobstruction, rhinnorhea sneezing and epistaxis. Patientwas a known asthmatic since many years and was oninhalers (fluticasone & salmeterol ) for 1 ½ years.Initiallythe patient responded but later on symptoms were

progressive and not relieved by medication. For the lastfew months she has noticed non progressing swelling inthe right eye with diminution of vision.. Right sided

polyposis was seen in frontoethmoidal and maxillarysinuses on CT scan of para nasal sinuses. There was

breakage in supero – medial wall of right orbit and lamina prepacia. The patient was advised Extensive FunctionalEndoscopic Sinus Surgery (FESS) and the pus and mucincollected during surgery was sent for histopathologicalexamination and fungal direct smear examination and

culture . On histopathology examination inflammatoryinfiltrate composed of eosinophils, lymphocytes and fewneutrophils was reported. On KOH examination septatehyphae were seen .The sample was cultured on SDA andon 3 rd day of inoculation buff coloured granular growthwas seen and LCB mount showed branched septatehyphae with smooth anneloco nidia of size about 5x6 μmand Scopulariopsis brevicularis was identified ;althoughantifungal susceptibility could not be done 2. On the basisof the published data authors have suggested thatS.brevicularis is invitro highly resistant to griseofulvin,tolnaflate, amphotericin B & flucytosine and moderatelysensitive to miconazole& ketaconazole 3. Itraconazole hasthe lowest MIC ;the patient was advised itraconazole400mg/day in three divided doses postoperatively for 1month & 200 mg/d after 2 month. On follow upexamination for 3 months the patient had no recurrent

polyp and improved symptomatically.Scopulariopsis species are among the most nondermatophytic fungi that cause onychomycosis and theyare also responsible for deep tissue infection. Inapproximately 90 % of invasive infections caused byScopulariopsis there were well predisposing factors – AIDS, Organ transplant, Corticosteroid therapy,Peritoneal dialysis , Cardiac disease & trauma. Eightspecies of Scopulariopsis have been reported as

producing infections in humans , five of them causingonly onychomycosis 4. S.brevicularis is the species mostfrequently seen clinically 5 Kriesel 6et al had reportedS.candida from a 12 years patient of Non Hodgkin

lymphoma in which locally invasive sinusitis was seen .She was successfully treated with surgical drainage anddebridement , G-CSF, amphotericin- B & itraconazole.while Ellison 5 et al from Milwaukee have reportedinvasive fungal sinusitis by S.acremonium in a patientwith leukemia who was treated with surgical resection,itraconazole along with chemotherapy . In IndiaS.brumptii has been reported from a AIDS patient withhydrothorax . 7 Scopulariopsis spp. are resistant toamphotericin-B and all the azoles except itraconazole ondmiconazole however the MIC for the agents is very high .Terbinafine has also shown to have promising results. Inthis case the child was put on fluticasone and β -agonist astreatment for asthma. and developed a non invasive masswhich was cured by extended FESS. Post operatively the

patient was advised itraconazole keeping in mind thatthe mass could be of fungal origin but oncescoplulariopsis was isolated itraconazole was advised inhigher doses i.e.. 400mg/day in three divided doses. So toconclude Scopulariopsis brevicularis can even presentwith invasive sinusitis and the fungal agent should always

be kept in differential diagnosis when such a mass isencountered in nasal cavity as treatment would grosslydiffer because other wise most of the time clinicians putthe patient on amphotericin – B and if they startitraconazole that is recommended in lower doses which

are not effective for scopulariopsis sp.

References1. Estrella MC, Lopez AG, Mellado E, Buitrago MJ,

Monjon A, Rodriguez- tudela JL. Scopulariopsisbrevicularis , a fungal pathogen resistant to broadspectrum antifungal agents. Antimicrobial agents andchemotherapy, july 2003:47(7):2339-41.

2. Lynne , Sigler & Michael J Kennedy fungi. Aspergillus,fusarium & other opportunistic moniliaceous fungi InManual of clinical Microbiology editors Murray PR,Baron EJ, Pealler MA, Tenover FC, Yolken FC. 7 th edn.American Society for Microbiology 1999.

3. Regli P, Ferrari H, Buffard Y, Goudard M, Bastien J.

Contribution a l‘etude de la sensibilite deScopulariopsis brevicularis (Bainier) aux antifongiques.Mykosen 27: 61-71.

4. Aguilar C, Pujol I, Guarro J. In vitro antifungalsusceptibilities of Scopulariopsis isolates. Anti microbialagents and chemotherapy, june 1999 :43(6) :1520-22.

5. Ellison MD, Hung RT, Harris K, Campbell BC. Reportof the first case of invasive fungal sinusitis caused byScopulariopsis acremonium. Arch otolaryngol head necksurg 1998;124:1014-16.

6. Kriesel JD, Adderson EE, Gooch WM, Pavia AT.Invasive sinonasal disease due to Scopulariopsis candida: case report and review of Scopulariopsis . Clinical andInfectious diseases. 1994;19:317-319.

7. Hydrothorax in association with S.brumptii in an AIDS

patient in Chennai, India. Transactions of Royal societyof tropical Medicine & Hygeine ;101(12):1270-72.


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What is your diagnosis?

Aggarwal S, Manchanda VClinical Microbiology and Infectious Diseases, Chacha Nehru Bal Chikitsalaya, Geeta Colony, Delhi

A 9 year old female presented to the Dermatology unit, with complaints of roughness of scalp hair with patchy loss of hairfrom scalp which she noticed 2 weeks back. The patient had minimal itching in the area of hair loss. She had history of use oftopical medication. Her systemic review was unremarkable. Dermatological examination at the time of presentation revealedthat her scalp hair were coarse. There were few non-scarring, non-inflammatory areas of patchy baldness (Figure 1). Alopecicareas had broken stubs of hair giving the look of black dot.

Figure 1. Presentation at the scalp area revealed that pa tient’s scalp hair were coarse. There were few non - scarring, non-inflammatory areas of patchy baldness. Alopecic areas had broken stubs of hair giving the look ofblack dot.

Figure 2 . KOH mount of the hair root revealed round, refractile bodies filling the medulla with broken shafts.

What is your differential diagnosis? What should be therapy of choice?


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Answer

Keeping the clinical suspicion of Tinea capitis (black dot)fungal scraping was taken from the involved area andslide of 10% KOH was examined under the microscopewhich revealed presence of fungal spores within the hairshaft. A diagnosis of Black dot Tinea capitis (Endothrix)

was made and the patient was started Griseofulvin.

DiscussionSuperficial fungal infections are among the mostcommon skin diseases, affecting millions of peoplethroughout the world. These infections, which occur in

both healthy and immunocompromised persons, arecaused by dermatophytes, yeasts and nondermatophytemolds. Effective treatment can reduce the duration ofsymptoms in patients with superficial fungal infections.

Dermatophytes, specifically Trichophyton,Epidermophyton and Microsporum species, areresponsible for most superficial fungal infections. The

estimated lifetime risk of acquiring a dermatophyteinfection is between 10 and 20 percent.

Dermatophytosis includes several distinct clinicalentities, depending on the anatomic site and etiologicagents involved. Clinically, involvement of scalp isreferred to as tinea capitis. Causative organisms: Dermatophyte fungal infectionmainly of two genera Microsporum and Trichophyton.The infection is commonly known as scalp ringworm.Transmitted by person to person contact, shared use ofcontaminated objects such as combs or by person toanimal contact (usually with a dog or cat).

Population at ri skChildren are most commonly affected, adults presentingwith tinea capitis may be immunocompromised e.g. HIVinfection.

Cli ni cal symptomsThe key clinical symptom is loss of scalp hair(alopecia). Tinea capitis is the single greatestcause of alopecia in children and it occursregardless of the species of fungus causing theinfection. There are four clinical presentationsof tinea capitis which may all occur singly ortogether in the same patient.

‗Grey patches‘o The hair breaks close to the surface or a few

millimetres above and there is scalp skinscaling;

o Small well defined patches join together toform larger ones;

o Hair loss is usually reversible but may beminimal and diffcult to see.

o Causative organisms are Microsporum (e.g. M.audouinii and M.canis) and Trichophyton.

o Usually ectothrix type of infection.‗Black dot‘

o The hair breaks at the surface of the scalp, andappears as swollen black dots, the distributionis diffuse;

o Hair loss is usually reversible;o

Causative organisms are Trichophyton species(e.g. T.tonsurans and T.violaceum );

o These infections are always spread from childto child.

Keriono Wet, purulent, inflamed and painful nodules

and plaques;o The most inflammatory form of tinea capitis

(often of animal origin);o Hairs do not fall out but can be pulled out

without pain;o Heals but there may be some scarring.o Secondary bacterial infection, cervical

lymphadenopathies are common.Favus

o Patches of redness and scaling over which thereare disc or cup shaped yellow crusts (scutula)

pierced by 1 or 2 hairs which do not break;o A foetid odour may be present;o After many years of infection atrophic patches

develop causing permanent alopecia. Because

of its chronicity, favus can be seen in adults;o These are most commonly seen in remote areasin central and east Africa;

o Causative organism is T.schoenleinii .

In general the clinical symptoms are more inflammatoryif the causative species is animal in origin rather thanhuman.

Diagnosis confir mation1. The key to the clinical diagnosis is the

presence of broken hair accompanied byscaling on the scalp. These may be hard to findand the scalp has to be examined thoroughly.For certainty of the diagnosis laboratoryconfirmation is required.

2. Hair root for examination is collected using ascalpel (Cut hair is no use as the fungi

penetrates the upper hair follicle)3. Samples should be examined in 10-20%

potassium hydroxide. Hyphae and arthrosporescan be seen.

4. Culture is done on Sabouraud Dxtrose Agarwith / without antibiotics.

Dif ferential Diagnosis1. Grey patch‘ - seborrhoeic dermatitis, psoriasis,

atopic dermatitis;2. ‗Black dot‘ seborrhoeic dermatitis, psoriasis,

atopic dermatitis, lichen planus, alopeciaareata;

3. Kerion- cellulitis, furunculosis;4. Favus- impetigo, ecthyma, crusted severe

seborrhoeic dermatitis.

Prevent ive measuresEnsure that cases are treated quickly to prevent spreadamongst a family or school population.Discourage the sharing of combs and head wear.

Treatment1. Topical treatments are ineffective, they do not

reach the inside of the hair shaft where the

infection resides, oral antifungals must begiven.


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2. Terbinafine, itraconazole and griseofulvin havesimilar efficacy. However terbinafine mayresolve the infection in less time if thecausative organism is a Trichophtyon species.

3. In some countries the only licensed treatmentfor tinea capitis in children is griseofulvin andit is the cheapest formulation.

4. Oral treatment should be continued for at least2 weeks (and up to 6 weeks) after thesymptoms have been resolved, until fungalcultures are negative. Treatment should becontinued if cultures are still positive. It may benecessary to increase the dose of the drug, both

griseofulvin and terbinafine can be used athigher doses for longer periods of time

5. It is very important that the drugs are taken atthe right time for the correct period of time andmaking sure that close contacts are treated ifinfection is present.

6. Additional measures to prevent the spread oftinea capitis include:o Screening close contacts and treating if

positive;o Cleaning brushes and combs in a bleach

solution and restricting the sharing of hair brushes, combs and caps.

Answers to the Crossword No. 1003


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pH MEASUREMENT, INDICATORS AND BUFFERSBatra P, Saxena S, Dutta RDept. of Microbiology, Lady Hardinge Medical College, New Delhi

Introduction

pH is a measure of the degree of acidity or alkalinity ofan aqueous solution. Historically, being defined as thenegative logarithm of the hydrogen ion concentration(pondus Hydrogenii, literally hydrogen exponent), tosimplify the handling of very small concentrations (on theorder of 10 – 7 moles liter – 1) encountered most commonlyin nature.The term pH was given by a Danish biochemist SorenSorensen who also invented the pH scale in 1909.Thus, pH = -log[H +] (where [H +] is the molarconcentration of solvated protons in moles per litre)

pH scale and its interpretation

H2O H+ + OH - at 25˙C or 298 K

K w [H+] [OH -][H 2O]

At equilibrium;K w = 1.00 x 10

-14 at 25˙C

Since at equilibrium, both the ions are present are presentin equal amounts:-

[H+]= [OH -]= 1 x 10 -7 moles / liter pH = - log [H +] = - log [10 -7] = 7 at 25˙C or 298 K

A solution is neutral if [H +] is equal to 10 -7, is acidic if[H+] is greater than 10 -7 and is alkaline if [H +] is less than10 -7.

Important points about pH scalea. Since it is a logarithmic scale, a

change of one unit of pH isequivalent to a ten fold change inhydrogen ion concentration, i.e. tenfold change in acidit y/ alkalinity

b. Since it is a reciprocal value, thelower the pH, the greater will be theacidity

Thus, a pH value of 7 acidic solution and a pH value

of 7 basic solutionThe pH scale is important because most of the pathogenicorganisms grow best around pH 7.0-7.5 except yeast andfungi grow at acidic pH of 5.0 or even lower. Thesecharacters are utilized in media preparation e.g.Media for most bacteria have a pH around 7.2 (neutral)while media for fungi pH around 5.4 (acidic)

Effect of pH on bacteria cell structure

Many cellular mechanisms sited in or sufficiently nearthe cell wall can be influenced by the pH of theenvironment. For instance,Penicillium chrysogenum showed decrease in the hyphal

length when the the pH exceeded 6 and at pH of 7 andabove, increasing number of hyphae showed swelling.

The terminal cytochrome oxidases are an important groupof enzymes influenced by the pH due to the fact that theirability to reduce terminal electron acceptors is a functionof the redox potential, which in turn, is markedly pHdependent.Toxic effects of hydrogen ion concentration can ariseindirectly through the penetration of the cell by moleculesundissociated in the environment which, on entry to thenear neutral interior, dissociate thereby changing theconditions inside the cell.this is reason why some of thecommonly used organic acid buffers are known to beinhibitory.

Effect of temperature on pH

The dissociation of molecules is highly temperaturedependent. Any change in temperature of the measuredsolution results in a change in the hydrogen ionconcentration of that solution and therefore in its pHvalue. Thus, the pH of a solution is inversely related totemperature

Methods of pH measurement

It is measured using pH indicator dyes or Electronic pHmeter

1. Methods depending upon the use of pHindicator dyes

Indicator dyes are weak organic acids or bases. They dissociate into ions when put in asolution. The color of the indicator in thesolution will then be determined by the ratio ofthe acid or alkaline form of dye. The color ofthe indicator developed in the solution will thusdepend on the ionic form which predominates.This can be explained by the numericalequation

color at a given pH

pH = pK indicator dye + log [form with alkaline color]

[form with acidic color ]

Various method of measuring pH based on indicatordyes:a. A pH indicator papers : The pH of the solution

can be determined by putting a drop of the solutionwithdrawn using a Pasteur pipette or a wire loop onthe paper or by dipping the paper directly in thesolution. It has the disadvantage of giving only anapproximate idea of pH.

b. Comparator method: The apparatus consists of a bakelite case with two holes at the top and rotatingdisks containing a series of colored glassescorresponding to the various pH values. It is

possible to get obtain disks of various indicatorsand the appropriate one can be inserted into the


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comparator. It has an advantage over pH indicator papers that accurate value of pH in the range of 0.1-0,2 pH units can be obtained.

c. Capillator method: It consists of a capillator i.e aseries of standard sized capillary tubes show colorscorresponding to different pH values over thewhole range of the indicator; Capillary tubes

identical in diameter to the capillator fitted with arubber teat and a watch glass. This method isobsolete and is no more in use.

2. pH meterIt is the most accurate method of measuring pHand was discovered by Sir Arnold O. Beckman

Figure 1: pH meter

It is based on the principle of potentiometry i.e. itmeasures the potential (voltage) caused by the hydroniumH3O+ ions.The apparatus consists of , a pH electrode referenceelectrode and a voltmeter

The Glass Membrane Indicator Electrode or pHelectrode:- The tip of the electrode, the pH transducer, isapproximately 0.1 mm thick. It is composed of silica(SiO 2) constituting 70% of glass, alkali metal oxide ofsodium or Lithium which provides Na or Li ions forexchange with H + ions and calcium oxide to provide thenetwork structure.

Reference electrodes:- These are made of silver or silverchloride (Ag/AgCl) electrodes or mercury or mercuricchloride (Hg/HgCl) or the calomel electrode. The AgClelectrodes are most commonly employed but have thedisadvantage of forming precipitates with the biologicalsamples and thus contaminating the solution. The calomelelectrodes are used for high precision electrochemical pHdetermination.Voltmeter:- Use to measure & transform voltage to pH.The difference in the electrode potential developed ismeasure of the hydrogen ion activity and thus a measureof the pH of the solution

Maintenance of pH meter

Before taking the pH measurements, allow it to warm tosufficient time as specified by the manufacturer andcalibrate the meter using buffers of known pH.While using, the glass bulb should be immersed to asufficient depth to cover the glass membrane adequately

but the bulb should not touch the beaker or any other hardsurface. Wash the electrodes with a stream of distilledwater in between the measurements. Never remove theelectrode from the solution when the measuring circuit isclosed. The electrode should be stored in water when notin use.Periodically the level of the filling solution in referenceelectrode should be checked and topped-up as necessary.A pH electrode should be regularly examined for saltcrystal build up and membrane and liquid junctiondeposits. For cleaning the deposits, soak the pH electrodein 6N HCl followed by thorough rinsing with distilledwater

Table 1: pH range of commonly used indicatorsIndicator Low pH

colorpH

rangeHigh pH

rangeUses

Methyl Red Red 4.4-6.2 Yellow Methyl red test

Bromo cresolpurple

Yellow 5.2-6.8 Purple Decarboxylase test, carbohydrate utilization media

Bromo thymolblue

Yellow 6.0-7.6 Blue Citrate utilization test, Teepol Lactose Agar, ThiosulphateCitrate Bile Sucrose Agar, Hugh & Leifson‘s Oxidationfermentation test

Phenol red Yellow 6.8-8.4 Red Urease test, Triple Sugar Iron Agar, Klingler Iron Agar,Xylose Lysine Deoxycholate Agar

Neutral red Red 6.8-8.0 Yellow MacConkey Agar, DeoxyCholate Citrate Agar

Litmus Red 4.5-8.3 Blue Used earlier in pH papers, but is obsolete now

Acid fuchsin Red 12.0-14.0

Colorless Is a constituent of Andrades indicator, which is used forcarbohydrate utilization test media

Universal pHindicator

Red 3.0-11.0 Reddishviolet

Mixture of several indicator dyes,giving a wide range ofcolor change with pH


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Digital PH meters

It is a new method of pH measurement which usesHigher-quality glass electrodes and Digital light-emittingdiode (LED) to display the Ph

Figure 2: Digital pH meter

pH meter is considered to be gold standard technique for pH determination as it can compensate for theenvironmental temperature differences. Unlike the pHindicator paper, it takes into consideration that theconcentration of the [H +] ions is also influenced by the

presence of other substances in the solution such as salts,ethanol, proteins etc.

Buffers

A buffer is a solution that resists a significant change in pH upon addition of an acid or a base. Chemically, a buffer is a mixture of a weak acid and its conjugate baseor weak base with its conjugate acid.When bacteria are grown in a culture medium, theyexcrete waste products such as acids that can alter the

pH of the medium. If this effect were to continue, themedium would become acidic enough to kill the bacteria.Buffers are added in the media to overcome this problem

by controlling the hydrogen ion concentration ofsolutions.

Mechanism of action

Let us take the example of acetate buffer to understandthe action of a buffer. It consists of a weak acid and itssalt with a strong base.

CH 3COOH CH 3COO- + H +

CH 3COONa CH 3COO- + Na +

On addition of strong acid, eg HCl in smallquantities

H+ +CH 3COO- CH 3COOH

H+ ions are used up and pH of the solution is practicallyunchanged.

On addition of strong bases, eg NaOH in smallquantities

OH - + CH 3COOH CH 3COO- + H 2O

OH - ions are used up and pH of the solutionremains practically unchanged

Uses of buffers

1. Phosphate buffer: pH 7.0, for Romanowskystaining

2. Carbonate-bicarbonate buffer: 50mM, pH 9.6as coating buffer in ELISA

Na 2CO 3 1.59g (15mM) NaHCO 3 2.93g (35mM)H2O 1000ml

3. Phosphate-buffered saline: pH 7.2 as washingsolution in ELISA

NaCl 80gKCl 2gKH 2PO 4 2g

Na 2PO 4 11.5g

4.

HEPES: N-2-hydroxyethylpiperazine-N'-ethanesulphonic acid (HEPES), pKa = 7.3 at37°C used in cell culture/ tissue culturetechniques.

5. Tris: (Hydroxymethyl) Aminomethane, used asan electrophoresis buffer for polyacrylamideand agarose gel electrophoresis. It is also usedduring DNA extraction and in cell culturetechnique. Tris should not be used at pH valuesunder pH 7.2 or above pH 9.0. The pH value ofa Tris buffer strongly depends on thetemperature. Therefore, Tris buffers should be

prepared at the temperature where it is to beused.

References:1. Robert Cruickshank, J.P. Duguid, B.P.

Marmion, R.H.A. Swain.medical microbiology,The practice of medical microbiology. pHmeasurements and buffers. Oxidation-Reduction Potentials, Suspension fluids,Preparation of glassware. Twelfth edition. VolII. Edinburgh: Churchill Livingstone

2. Munro A.L.S (1970) Methods in Microbiology.Vol 2 measurement and control of pH values.

pg 39-90. London: Academic press3. J.G. Collee, A.G.Fraser, B.P. Marmion, A.

Simmons. Mackie &McCartney. Practical

Medical Microbiology. Fourteenth editionSerological techniques pg 183-188. ChurchillLivingstone

4. Norman F. Sheppard, Jr., Anthony Guiseppi – Elie. pH Measurement.c2000. CRC Press LLC.available from .

5. http://ehow.com/about_6370937-function-tris- buffer-dna-extraction_.html

6. J D Williamson., P. Cox. Use of a new buffer inthe culture of animal cells.J.gen. vir.1968(2):309-312


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Candida — An Emerging Pathogen

Bhagat S, Rajani M, Saxena S, Dutta R.Department of Microbiology, Lady Hardinge Medical College, Delhi

Introduction:

Candidiasis is the commonest fungal disease found inhumans affecting mucosa, skin, nails and internal organs.It is caused by various species of yeast like fungi

belonging to genus Candida .The genus Candidacomprises about 200 species of which close to 20 have

been associated with pathology in humans or animals,including species such as Candida famata or Candidainconspicua which have been added recently withCandida albicans as the representative species 1.The Candida fungus is both normal flora and an invasive

pathogen. The range of infection with Candida species

varies from a benign local mucosal membrane infectionto disseminated disease. Severe disease is typicallyassociated with an immunocompromised and familycryptococcaceae. There are 163 anamorphic species ofgenus Candida with telemorphs in atleast thirteengenera. 2

Pathogenicity and Pathogenesis:

Virulence factorsThe virulence traits of Candida spp. particularly of themajor pathogen, C. albicans, to which possible roles in

pathogenesis of candidiasis have been attributed , are believed to be associated with:1. The ability of the fungus to bind (attach, adhere) to host

tissue as an initial step in the recognition andinteraction with the host. In vitro systems showed thatCandida can adhere to a variety of substrates, such asexfoliated human epithelial cells ( buccal, vaginal,dermal), human tissue lines, animal tissue segmentsor inert surfaces( various polymers used forindwelling medical devices) with C.albicans generally the most adherent Candida species. Alsoimportant is an associated phenomena — Biofilmformation — which adversely effects the hostsresponse to infection and causing difficulties intherapy 3.

2. Production of enzymes that could facilitate tissue penetration and invasion, such as secretory aspartyl

proteinases( SAPs) and phospholipases4.

3. Yeast hyphal morphogenetic transformation whichcould facilitate penetration and also helps the microbeto evade the hosts defence system. Hyphal formshave higher phospholipase concentration at their tipsand being larger in size are more resistant to

phagocytosis 5.4. Phenotypic switching which express the fungal

plasticity, contributing to its adaptability to variousanatomic sites of human body and thereby possiblyenabling the variety of clinical entities it causes 6.

5. Various immunomodulatory effects of fungaldeterminants, which could contribute to reducedactivity of hosts defense system.

Pathogenesis

The Candida is a human commensal, so that theinfectious source is mostly endogenous 7. A GI tract isconsidered a major reservoir for Candidiasis. FromGI tract the fungus can invade the blood streamfollowing the damage to the GI mucosa, such asinduced by anticancer treatment, or major surgeryand spread hematogenously into various organscausing deep- seated/ disseminated infections 8. It is

believed that Candida may also be able to cross theintact GI mu cosa by a process termed ―presorption‖,following fungal overgrowth which can result fromchanges in the normal balance of the microbial floradue to extensive antibiotic treatment 9. However,

Candida can be introduced from exogenous sources as well. Like introduction through various cathetersand lines or other indwelling/ prosthetic medicaldevices. This route is of particular importance in thedevelopment of deep-seated and systemic candidiasis.

Clinical Features:The clinical manifestations of candidiasis are extremely

varied, ranging from acute, subacute, chronic andepisodic. Involvement may be localized or systemic.

Candidal infections commonly occur in warm moist bodyareas, such as underarms. Usually the skin effectively

blocks yeast, but any breakdown or cuts in the skinmay allow this organism to penetrate.

Signs and symptoms

Signs and symptoms of a candidal infection can varydepending on the location of the infection 10 (Table 1).

A. Mucocutaneous

Thrush : Thick, white lacy patches on top of ared base can form on the tongue, palate, orelsewhere inside the mouth.Vaginitis: There is white discharge that isthick and often described as having a cottagecheese appearance. The infection typicallycauses itching and irritates the vagina and

surrounding outer tissues.Chronic mucocutaneous candidiasis describes agroup of Candida infections of the skin, hair,nails, and mucous membranes that tends tohave a protracted and persistent course.Chronic mucocutaneous candidiasis isfrequently associated with endocrinopathies,such as Hypoparathyroidism, Addisons disease,Diabetes mellitus, Hypothyroidism etc.

B. Cutaneous

The most cmmon species isolated is Candidaalbicans. Other commonly isolated species areC. tropicalis , C.guilliermondii , C.kefyr , C.krusei , C. parapsilosis .


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Table 1. Clinical classification of Candidiasis 2

1. Infectious disease

A. M ucocuataneous M ani festationsOral : thrush , stomatitis, glossitis, chelitisAlimentary: oesophagitis, gastritisVulvovaginitis: balanitis, balanoposthitisChronic mucocutaneous candidiasisOcular candidiasis

B. Cutaneous M ani festationsIntertriginous and generalizedParonychia and onychomycosisDiaper dermatitisCandidal granuloma

C. Systemic M ani festation sUrinary tractEndocarditisPulmonary candidiasisMeningitisCandidemia

DisseminatinArthritisOsteomylitisEndophthalmitis

2. AllergicCandididsEczemaAsthmaGastritis

I ntertri go : On examination a rash that beginswith vesiculopustules that enlarge and ruptures,causing maceration and fissuring.Diaper dermatitis: The superficial skininfections appear as red flat rash withscalloped edges. There are usually smaller

patches of similar appearing rash nearby,known as "satellite lesions." These rashesmay cause itching or painParonychia and onychomycosis : arefrequently associated with immersion of thehands in water and with diabetes mellitus.There is an area of inflammation that

becomes warm, glistening, tense, anderythematous and may extend extensivelyunder the nail. It is associated with secondarynail thickening, ridging, discoloration, and

occasional nail loss.General ized cutaneous candidiasis: This isan unusual form of cutaneous candidiasisthat manifests as a diffuse pruritic eruptionover the trunk, thorax, and extremities.

C. Systemic

GIT Candidiasis Esophageal candidiasis Commonly seen in patients taking

chemotherapy, broad-spectrum antibiotics orinhaled steroids, the presence of HIV infectionor hematologic or solid-organ malignancy.It

may lead to painful dysphagia, chest pain,

nausea, vomiting. The white patches are seenon endoscopy.

Commonly implicated species are C. albicans >C. glabrata >C. tropicalis

Respiratory tract candidiasis The respiratory tract is frequently colonized

with Candida species, especially in hospitalized patients. It can manifest as Laryngealcandidiasis, Candida tracheobronchitis,Candida pneumonia.

Genitourinary tract candidiasis Vulvovaginal candidiasis Candida balanitis (white pruritic patches on

penis) Candida cystitis Asymptomatic candiduria (seen in

catheterized patients) Ascending pyelonephritis (with use of stents

and indwelling devices)

Hepatosplenic candidiasis (chronic systemic candidiasis) Hepatosplenic candidiasis is a form of systemic

candidiasis in patients with an underlyinghematologic malignancy and neutropenia anddevelops during the recovery phase of aneutropenic episode.

CNS infections due to Candida species CNS infections due to Candida species are rare.

Predominant species is C. albicans . More common in AIDS patients and premature

infants.

Usually a manifestation of disseminatedcandidemia

Cardiovascular System: Most commonly endocarditis seen with large

vegetations Seen in mainly iv drug addicts, prosthetic heart

valve patients, cardiac surgery patients The common implicated species are C. albicans

>C. parapsilosis > C. tropicalis

Disseminated candidiasis This is frequently associated with multiple

deep organ infections or may involve single

organ infection. Can involve CNS, Kidney, Heart, Eyes etc. Seen in cancer, leukemic, post – surgery,

transplant patients, premature infants Non-albicans Candida accounted for 70% of

candidemia in a Northern Indian pediatricintensive care unit. Candida species isolatedwere Candida tropicalis (48.4%), C.albicans (29.7%), C. guilliermondii (14.1%),C. krusei (6.3%), and C. glabrata (1.6%).

Other Candida species that have emerged areC. parapsilosis and C. dubliniensis .

Laboratory Diagnosis 2,10,11

1. Direct examination


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KOH/Saline wet mount Fungal Calcoflour white stain Yeast cells ( 4-8 µm) with budding

and pseudohyphae seen H & E and Gomori‘s methenamine

silver stain for demonstration ofelements in tissues.

2. Fungal culture( Table 2) On SDA with antibodies and

incubated at 25 0Cand 37 0C For systemic infections blood culture

is done in biphasic medium like BHIAgar broth and incubated a bothtemperatures.

3. Chlamydospore formation ( Table 2) On CMA or rice starch agar and

incubated at 25 0C.

4. CHROMagar Candida (Table 2) Rapid , plate based test for

simultaneous isolation andidentification of various candida spp.

based on formation of different colorsas a result of biochemical reaction.

5. Biochemical tests

Based on sugar fermentation andassimilation are of immenseimportance for yeast identification

6. Germ tube formation Positive in C. albicans & C.

dubliniensis ( Also called as ReynoldsBraude Phenomenon)

7. Immunodiagnosis Numerous serological and molecular

techniques have been developed forthe diagnosis of Candida spp.( Table3)

8. Detection of metabolites D-Arabinitol produced by C.

albicans , C. tropicalis , C. parapsilosis , C. pseudotropicalis, C. guilliermondii but not by C. krusei and C. glabrata

Similarly D- mannose is a metaboliteof Candida species and can bedetected in sera by gas liquidchromatographgy.

G-test for detection of glucan mayalso be performed.

Table 2: Characteristics of Important Candida species

Colony morphology

on SDA

Species Characteristics on

CMA

CHROMagar Importance

C. albicans Cream, pasty ,smooth

Large thick walledterminalchlamydospores

Light green to bluish green

Is a representative speciesImportant cause of bloodstreaminfections in immunosupressed personsResponsible for outbreaks in hospitals

C. tropi cali s Cream , off white ,glistening to dull,smooth with lateralfringes

Blastospore singly orin small groups

Important pathogen in hematologicalmalignancies, and in transplant patientsImportant cause of bloodstreaminfections

C. kru sei Flat , dull , drycolonies. On

prolongedincubation greenishyellow dull,

wrinkled colonieswith lateral fringes

Elongated cells withtree like arrangementor cross match stickappearance.Blastospores

elongated andverticilliate.

Important pathogen in hematologicalmalignancies, and in transplant patientsAlso important cause of vaginitisResistant to azoles

C. par apsil osis Creamy , lacy pattern

Blastospores singlyor in small clusters.Large mycelia cellscalled giant cells

Localized and deep seated infectionslike endocarditis, septicemia, arthritisFungemia due to CVCs as well as

parenteral nutritionC. glabr ata Glistening smooth

cream colored ,small sized, nomycelia fungus

Small blastospores,no pseudohypahae

Pink to purple Infection in immunosupressed patientsImportant cause of vaginitis, denturestomatitisImportant cause of bloodstreaminfections( 11-16% of all candidemiacases)Resistant to azoles


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Table 3: Serological tests for invasive Candidiasis

A. Detection of Antibodies

Slide agglutination testImmunodiffusionPhytohaemagglutinationCoelectosynersisImmunoprecipitationA and B immunoflouresence

B. Non specific Candida Antigens

Latex agglutinationImmunoblotting

C.Cell wall component

Cell wall mannoprotein( CWMP)Β-(1,3) D- glucan

D.Candida Enolase Antigen testing

Treatment :2,10

For oral and mucocutaneous lesions 1% gentianviolet, Nystatin, azole creams can be used.

For Systemic infections iv Amphotericin B isindicated.

Also Amphotericin B can be combined withFlucytosine.

Drug resistance in Candida spp is now verycommon , therefore antifungal susceptibilitytesting should be performed ( M-27A).

C. krusei and C. glabrata are inherentlyresistant to azoles and is emerging cause offungemia in patients with hematologicalmalignancies.

Immunotherapy using G-CSF and GM-CSFcan be given

References

1. Meyer SA., Payne RW., and Yarrow D.Candida Berkhouit. In : Kurtzman CP andFellJW, The yeasts, a taxonomic study, 4 th ed.Amsterdam: Elsevier.1998.p454-573.

2. Candidiasis. In Textbook of medical mycology. 3 rd ed., Edited by Jagdish Chander. Mehta

publisher.2009. p266-2903. Segal E, Soroka A and Schecter A. Correlative

relationship between adherence of Candidaalbicans to human vaginal epithelial cells in

vitro and vaginitis. J Med VetMycol.1984. 22: p191-200.

4. Ruchel R, Bernardis F et al. Candida acid proteinases. J Med Vet Mycol.1992:30:p123-32.

5. Madhani HD and Fink GR. The control offilamentous differentiation and virulence infungi.Trends Cell Biol.1998:8;p348-353.

6. Soll DR. Phenotyping switching. In : CalderoneRA. Candida and Candidiasis. Washington DC.ASM Press.2002.p123-43.

7. Kennedy MJ .Adhesion and associationmechanisms of Candida albicans.Curr Top MedMycol.1998: 2;p123-32.

8. CunninghamCG, Morgan RJ et al. Functionaland structural changes of the human proximalsmall intestine after cytotoxic therapy. J clinPathol.1985: 38 ,265-70.

9. Krause W, Matheis H and WulfK. Fungemiaand funguria after oral administration of

Candida albicans. Lancet. 1969. 1: 598-9.10. Esther Segal and Daniel Elad. Candidiasis. InTopley and Wilson.10 th ed., Edited by BrianWJ Mahy and Volker ter Meuleu.Pub ASMPress.2005: p 579-623.

11. Mycology. In Koneman Color Atlas and TextBook of Diagnostic Microbiology.6 th ed.,Edited by Washington Winn, Stephen Allen etal. Pub Lippincott Williams &Wilkins.2006.p1153-1246.


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Crossword puzzle no. 1003Arora S & Dawar R,Indraprastha Apollo Hospitals, New Delhi

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Jeevanu Times Dec 2010