Candida

Candia

1. Candida

2. Candida Family: Sachharomycetaceae Phylum: Ascomycota Approx 200 species About 20 associated with pathology in humans and animals

3. Candida Candida – anamorph (asexual form) Teleomorphs of several genera demonstrated for different species of Candida Teleomorph genera: Clavispora Debaromyces Issatchenkia Kluyveromyces Pichia Yarrowia

4. Habitat Ubiquitous yeast Found on many plants Normal flora of GI tract of mammals and mucocutaneous membranes of humans Present in all areas of human GI tract Common species in GI tract C. albicans C. tropicalis C. parapsilosis C. glabrata

5. Major pathogenic species C. albicans C. glabrata C. krusei and its teleomorph Issatchenkia orientalis C. kefyr and its teleomorph Kluyveromyces marxianus C. guilliermondii and its teleomorph Pichia guilliermondii C. parapsilosis C. tropicalis C. lusitaniae and its teleomorph Clavispora lusitaniae

6. Morphology Polymorphic yeast , i.e., yeast cells , hyphae and pseudohypha e are produced Ability to assume various forms may be related to the pathogenicity Yeast form: 10-12 microns in diameter gram positive grows overnight on most bacterial and fungal media pseudohyphae may be formed from budding yeast cells that remain attached to each other. Spores may be formed on the pseudomycelium , called chlamydospores and can be used to identify different species of Candida .

7. Morphology

8. Morphology On Glucose Peptone Agar (GPA) after 3 days at 25 o C Diameter 2-3mm White to cream colored Smooth or umbonate May become wrinkled after further incubation Dull to glistening On corn meal agar: intraspecies variation

9. Candida albicans On corn meal agar after 3 days of incubation: produce true mycelia and pseudomycelia , grape like cluster of blastoconidia at the septa and chlamydoconidia at the ends of hyphae or their short lateral branches

10. Candida albicans Incubation for 2 hours in 10% serum at 37 o C: forms typical cell elongations known as germ tubes

11. Epidemiology of C. albicans Habitat human commensal major reservoir- GI tract can invade into bloodstream from GI tract afgter damaging GI mucosa Source of infection Endogeneous : primarily can spread hematogenously into various organs Exogenous: introduction into the body through medical devices, catheters important in the development of deep-seated and systemic infections

12. Epidemiology of C. albicans Transmission : Person to person transmission not predominant In case of oral thrush, from mother with vaginal candidiasis to newborn, during birth sexual transmission from females with vaginitis to their sexual partners Risk factor Prolonged therapy with broad spectrum antibiotics

13. Clinical significance Disease: Candidiasis Clinical manifestations may be acute, sub acute, chronic or episodic Can cause various forms of infections, ranging from superficial manifestations involving skin, nails and mucosal surfaces, to deep-seated infections involving various internal organs to disseminated disease Diseases sub-divided into 2 large groups: Mucocutaneous candidiasis Deep-seated candidiasis

14. Mucocutaneous candidiasis 3 forms Cutaneous infections Nail infections Mucosal infections

15. Cutaneous candidiasis 1. Candidal intertrigo ( Intertriginous candidiasis ) Most common form Organisms colonize skin folds, particularly in moist and macerated sites ( axilla , groin, inter and sub mammary folds, umbilicus) Form erythrematous lesions with vesicles (elevation of skin with clear fluid) and pustules (elevation of skin with purulent fluid) in combination with pruritis (severe itching)

16. Cutaneous candidiasis (contd.) 2. Erosio interdigitalis Skin folds between the fingers become macerated and itchy Associated with excessive exposure to moisture Common in dishwashers, barlenders , fruit cannery workers 3. Perianal rash (Diaper candidiasis ) Involves infants wearing nappies Rashes seen in perianal area and on the buttocks Infection may be secondary to pre-existing inflammatory condition

17. Cutaneous candidiasis (contd.) 4. Chronic mucocutaneous candidiasis Relatively rare condition Most severe clinical form of superficial candidiasis Cause: C. albicans Characterised by the presence of persistent lesions, with high rate of recurrence, starting in early childhood and persisting throughout the individual’s lifetime Lesions at various skin site, not limited to skin folds Warty lesions termed as candida granuloma

18. Nail infections ( Paronychia and Onychia ) Agent: C. albicans (major), C. parapsilosis , C. guilliermondii Characterised by prominent swelling, redness, pain Paronychia : infection of nail folds (fold of skin supporting nail at its base) Onychia : infection of nails Affected nails become discolored, eroded, brittle,detached from nail bed and painful Paronychia may or may not lead to onychia .

19. Mucosal infections Oral candidiasis Vaginal candidiasis

20. Oral candidiasis Most frequent Major agent: C. albicans Others: C. glabrata , C. guilliermondii , C. parapsilosis , C. tropicalis Several different clinical forms Acute pseudomembranous candidiasis (oral thrush) Acute atrophic candidiasis Chronic atrophic candidiasis Chronic hyperplastic candidiasis Angular chelitis

21. Oral candidiasis 1. Oral thrush Characterised by white-grey lesions on the gums, tongue,or oral mucosa, can appear as single lesion or as confluent large plaques Lesions covering large area may be painful and disturb food intake May spread to the oesophageal mucosa, and cause dysphagia Generally occurs in AIDS patient, cancer patient, debilitated individuals, elderly people and in infants of the mothers with vaginal candidiasis

22. Oral candidiasis 2. Acute atrophic candidiasis Characterised by painful, erythematous mucosa, particularly on the tongue May cause loss of tongue paillae , affecting food intake. 3. Chronic atrophic candidiasis Known as denture stomatitis Occur in elder individuals wearing dentures Characterised by erythema and/or oedema of the mucosa under the dentures Not painful

23. Oral candidiasis 4. Chronic hyperplastic candidiasis Also known as candida leucoplakia Rarer condition Characterised by white plaques, can appear on various sites of oral mucosa Can’t be removed like pseudomembranous form May transform into a malignant state 5. Angular cheilitis Characterised by erythema and fissures at the folds of the corners of the mouth May be associated with denture stomatitis or oral thrush

24. Vaginal candidiasis Common infection in females of reproductive age group, primarily during the fecund period Prevalence : 5-20% Prevalence increases in particular groups like pregnant or diabetic women, using oral contraceptives (hormonal effect) and after antibiotic treatment Cause: C. albicans , C. glabrata , C. tropicalis Imporatant feature: recurrence of infection Transmission: sexual transmission to male partners In men, characterised by balanitis with lesions and erythrema

25. Vaginal candidiasis (Contd.) Syndrome: Complaints of vulvovaginal pruritis and discharge (thick curd like or thin) Erythema of the vulvovaginal mucosa and also of perianal area Lesions on the mucosal surface are basically adherent plaques May cause pain and discomfort during sexual intercourse

26. Deep-seated candidiasis Infection of visceral organs and possibly to multiple organs or disseminated disease Includes Candidiasis of GI tract Candidiasis of respiratory system Candidiasis of CNS Candidiasis of renal and urinary system Candidiasis of cardiovascular system Hematogenous disseminated disease Ocular infection and a variety of other specific manifestations

27. Deep-seated candidiasis Candidiasis of GI tract Oesophagitis Painful dysphagia and chest pain White patches on oesophageal mucosa as in oral candidiasis May be associated with oral candidiasis 10-30% of AIDS patients with oral candidiasis may also have candidal oesophagitis

28. Deep-seated candidiasis Candidiasis of GI tract Gastrointestinal candidiasis Though being normal flora of GI tract, clinical involvement of mucosal surfaces of the stomach and/or intestine with mucosal white plaques and ulcerations are found Plays an important role in the pathogenesis of disseminated candidiasis

29. Deep-seated candidiasis Candidiasis of respiratory system Involves lungs Bronchopneumonia originates from hematogenous spread of the fungus as a part of a disseminated infection or from introduction of pathogen into the lungs CNS candidiasis C. albicans - cause Risk group- AIDS patients and pre-term infants Seen as part of disseminated candidiasis , involving meninges , abscess formation in brain tissues

30. Deep-seated candidiasis Candidiasis of cardiovascular system Cause: C. albicans , C. parapsilosis , C. tropicalis Cause clinical manifestations in various organs of the cardiovascular system: pericardium, myocardium and endocardium (common) Endocarditis : primarily seen in IV drug users and in individuals with impaired heart valves. Also may occur in patients after cardiac surgery procedures or as a sequelae of anticancer therapy

31. Deep-seated candidiasis Renal and Urinary tract candidiasis Lower urinary tract infection: Frequently seen in association with indwelling catheters Source: GI and genital biota More in women Also found in diabetic patients Infection may be mild or severe No unique symptoms Clinical feature: formation of fungal masses, which may cause obstruction and impair normal urine flow

32. Deep-seated candidiasis Deep-seated candidiasis Renal infection Originate from hematogenous dissemination of Candida spp or as an ascending UTI Characterised by microabscess formation, primarily in the cortex of the kidneys

33. Deep-seated candidiasis Disseminated candidiasis Multi-organ infection and possibly candidemia May include CNS, kidneys, heart, eyes or other organs or systems Hepatosplenic candidiasis - a specific clinical manifestation of disseminated infection Seen in cancer patients, particularly those with acute leukaemia , in patients after surgery (GI and cardiac), in transplant recepients (bone marrow), in preterm infants, burn patients and drug addicts Ocular infection- common, typical white (cotton-like)lesions in the retina Cutaneous- nodular lesions on the skin

34. Virulence factors Adherence: biofilm formation, a significant factor in the pathogenesis affecting the host’s response to infection and causing difficulty in therapy Dimorphism: Specific enzymes that facilitate tissYeast-hyphal morphogenetic transformation, which facilitate penetration and assist the microbe to evade the host defense system Interference with phagocytosis , immune defenses and complement Production of specific enzymes that could facilitate tissue penetration and invasion such as secretory aspartyl proteinases (SAPs) and phospholipases Germ tube: adhesin on the surface of tube Acidic metabolites Growth rate and undemanding nutrient requirement Phenotypic switching (changes in colony morphology and in antigenicity , contribute ot adaptability into various anatomic sites of the body and also play the role in transition from commensalism to pathogenicity )

35. Laboratory diagnosis of Candida Depends on the nature of infection, whether mucocutaneous or deep-seated forms Mucocutaneous candidiasis Sample: skin, nail or mucosal surface swabs Includes 2 steps: Direct examination of the specimen to demonstrate fungal presence Isolation of the fungus and its identification

36. Laboratory diagnosis of Candida 1. Direct examination (wet mount method) Treat specimen with keratinolytic substance (10-30% KOH) to facilitate the microscopic examination of the specimen Demonstration of fungi enhanced by the addition of cotton blue or acid Parker’s ink the use of calcofluor white, a fluorochrome with an affinity for chitin and glucan which makes a demonstration of fungal elements with a fluorescent microscope relatively simple Gram’s staining for nail and skin specimens-not generally done Examination of infected material reveals the presence of budding yeast cells, pseudohyphae and hyphae

37. Laboratory diagnosis of Candida Mucosal infections Vaginal and oral swabs preferably kept in transport medium before being processed in the lab Oral lesion specimen also obtained by scrappings Both wet mount and fixed mount can be done Wet mount: unstained slide prepared in saline or water or stained with lactophenol cotton blue or calcofluor white Fixed mount: stained using Gram’s stain, Geimsa stain or methylene blue

38. Laboratory diagnosis of Candida Microscopic examination of specimes from vulvovaginitis or oral candidiasis will reveal the presence of budding yeast cells, pseudohyphae and hyphae Presence of hyphal elements in direct microscopic examination important (vagina and mouth normally colonised by Candida spp ) Presence of hyphal elements indicates infection

39. Laboratory diagnosis of Candida Culture Isolation of Candida spp Routine medium: SDA supplemented with antibiotics ( chloramphenicol , gentamycin and /or tetracyclin ) to prevent bacterial overgrowth Other medium: SDA with cycloheximide to prevent the growth of air-borne molds Incubation at 28 o C or/and at 37 o C for 2-3 days Growth can also be observed at 24 hours and some species take more than 3 days

40. Laboratory diagnosis of Candida Identification Morphological characteristics SDA: appears smooth, but some species ( C. krusei ) from dry, creamy colonies CHROM agar: uses chromogenic substances based on the reaction between specific enzymes of different species and chromogenic substrates, which results in the formation of differently colored colonies rapid presumptive identification of C. albicans , C. krusei and C. tropicalis Wet mount or fixed mount can be done to observe the cellular morphology of isolates

41. Different species of Candida on Chrome agar C. albicans , C. glabrate , C. tropicalis , C. krusei

42. Laboratory diagnosis of Candida Physiological/ Biochemical characterization characterised by patterns of their use of specific carbohydrate and nitrogen substances Serologic identification Can be identified using specific antisera by slide agglutination test Not used as a routine method

43. Laboratory diagnosis of Candida Deep-seated candidiasis More difficult than in case of mucocutaneous forms Includes direct microscopy isolation in culture immunodiagnosis (presence of antibodies and/or the presence of microbial antigens in patient’s body fluid

44. Laboratory diagnosis of Candida Direct examination Demonstration of the presence of candidal cells and/or hyphal forms in clinical samples from normally sterile sites such as CSF, bronchial aspirate, sample from bone marrow and other tissues Sputum and urine specimens may be contaminated with normal microbiota Tissue biopsy can be prepared and stained by histopathological techniques

45. Laboratory diagnosis of Candida Culture Isolation of Candida Difficult to isolate if the infection is localized in internal organ Sample: Blood, CSF, tissue biopsies Media: SDA with antibiotics Identification Similar as with mucocutaneous candidiasis

46. Laboratory diagnosis of Candida Immunodiagnosis For deep-seated infection, microscopy and culture methods not sufficient as in case of mucocutaneous infection Based on Detection of antibody production Detection of fungal antigens in body fluids and in serum Antibody detection Agglutination technique representing anti- mannan antibodies, can also be found in healthy individuals and with superficial infections not useful for diagnosis of deep-seated infection Antibody detection for the presence of antibodies to candidal internal antigens released into patient’s body during invasion Techniques: gel immunodiffusion , CCIE, ELISA, latex agglutination

47. Laboratory diagnosis of Candida Immunodiagnosis Antigen detection Important diagnostic tool, particularly in immunocompromised patients Techniques: LA and ELISA Detection in serum, urine and other body fluids Antigens: mannan , an undefined glycoprotein, a 47 kDa protein, enolase

48. Treatment commonly treated with  antimycotics ;  include topical  clotrimazole , topical  nystatin , fluconazole , and topical  ketoconazole Localized infection Oral candidiasis :topical treatments or oral medication Candida esophagitis :orally or intravenously; for severe or azole -resistant esophageal candidiasis , treatment with amphotericin B may be necessary. A one-time dose of fluconazole is 90% effective in treating a vaginal yeast infection. For vaginal yeast infection in pregnancy, topical  imidazole  or  triazole   antifungals . Blood infection intravenous fluconazole or an  echinocandin  such as  caspofungin  may be used. Amphotericin B  is another option.