Identification, Susceptibility & Resistance

1. Identification, Susceptibility & Resistance Dr Caroline B. Moore Mycology Reference Centre University Hospital of South Manchester The University of Manchester

2. Yeasts

3. Why bother with identification & susceptibility testing? • Significant number of invasive fungal infections • Increase in ‘at-risk’ patient population

4. Why bother with identification & susceptibility testing? • Significant number of invasive fungal infections • Increase in ‘at-risk’ patient population • Increase in non-C. albicans species • Increase in ‘rarer’ species

5. Proportion of nosocomial Candida infections caused by different species in a teaching hospital Berrouane et al. J Clin Micro 1999; 37:531

6. Why bother with identification & susceptibility testing? • Significant number of invasive fungal infections • Increase in ‘at-risk’ patient population • Increase in non-C. albicans species • Increase in ‘rarer’ species • Increase in drug resistance

7. Increasing fluconazole resistance in Intensive Care Unit Moore et al. ECMM 1998

8. Why bother with identification & susceptibility testing? • Significant number of invasive fungal infections • Increase in ‘at-risk’ patient population • Increase in non-C. albicans species • Increase in ‘rarer’ species • Increase in drug resistance • More drug choices available • Informed therapeutic choice

9. How do we identify yeasts? • Culture morphology Chromagar

10. How do we identify yeasts? • Germ tube test • Microscopic morphology Terminal chlamydospores Arthrospores • Other tests

11. How do we identify yeasts? • Traditional methods • Wickerham tests Auxacolor • Commercial kits • numerous! Vitek-2 API ID 32C • Molecular methods

12. MICs He uses statistics like a drunken man uses lamp-posts ... For support rather than illumination

13. Do we have a good test of susceptibility for yeasts? • CLSI (NCCLS) M27-A3 method • USA standard • EUCAST Document E-Def 7.1 method • European standard Extensive clinical correlation work

14. Do we have a good test of susceptibility for yeasts? • Disc diffusion • no MIC obtained • screening method • E-test strips • MIC value obtained • problematic endpoints

15. Do we have a good test of susceptibility for yeasts? • An array of commercial formats • Vitek-2 • YeastOne • Fungitest • Others… Some are more equal than others! • Molecular methods

16. Candida albicans • Most common cause of candidosis (50-70%) • Can cause a wide range of diseases • May cause vaginal and oral/oesophageal thrush • Produces germ tubes • Attributable mortality (18-25%) • differences in patient age and underlying illness

17. Candida albicans • Azole susceptibility can depend on HIV status FLU ITR VOR POS AMB 5FC CASP C.albicans++ ++ ++ ++ ++ ++ ++ C.albicans - FLU-resistant -+ ++ + ++ ++ ++ Rates of resistance seen in our laboratory 1992-2006 flucytosine 6% fluconazole 1.2% 5% of C. albicans with reduced susceptibility

18. Candida parapsilosis complex • Candida parapsilosis, Candida orthopsilosis, Candida metapsilosis • 2nd most common species in blood, related to catheters and glucose solutions including TPN • Often seen in neonates • Generally do not cause thrush • Less pathogenic than C. albicans

19. Candida parapsilosis complex FLU ITR VOR POS AMB 5FC CASP C.parapsilosis++ ++ ++ ++ +++- Rates of resistance seen in our laboratory 1992-2006 fluconazole 0.4%

20. Candida glabrata • 3rd or 4th most common species in blood • Increasing in many institutions • Common cause of thrush, particularly vaginal • Generally thought as unable to produce pseudohyphae in vitro • Evidence of ability to grow as filamentous organism

21. Candida glabrata • Usually reduced susceptibility to fluconazole • Responds poorly to amphotericin B FLU ITR VOR POS AMB 5FC CASP C.glabrata+ + + + +++ ++ Rates of resistance seen in our laboratory 1992-2006 fluconazole 53%

22. Candida tropicalis • Usually 4th most common species in blood, much commoner in some institutions • Generally does not cause thrush • More invasive than other Candida species • High attributable mortality (33-50%) • High frequency (~80-100%) of infection if coloniser during neutropenia

23. Candida tropicalis • Usually fluconazole susceptible, but may develop resistance quickly FLU ITR VOR POS AMB 5FC CASP C.tropicalis+++ ++ ++ ++ ++ ++ Rates of resistance seen in our laboratory 1992-2006 flucytosine 20% fluconazole 46%

24. Candida krusei • 5th most common species in blood • Does not cause thrush, except in late-stage AIDS • High mortality in leukaemic patients

25. Candida krusei • May be a breakthrough species • Always fluconazole resistant and amphotericin intermediate FLU ITR VOR POS AMB 5FC CASP C.krusei-+ + + + + ++

26. Cryptococcus neoformans • Neurotropic fungus • Most common predisposing factor is AIDS • Also organ transplant recipients or cancer patients receiving chemotherapeutics • Produces a polysaccharide capsule - major virulence factor

27. Cryptococcus neoformans • Combination therapy generally used FLU ITR VOR POS AMB 5FC CASP Crypto. neoformans+ +++ ++ +++-

28. Rhodotorula mucilaginosa Image Courtesy of Carsten Kettner Saccharomyces species Malassezia species High degree of mortality

29. Species of….TrichosporonGeotrichumBlastoschizomyces Can be intrinsically resistant to some antifungal drugs

30. Moulds - the Aspergilli

31. Increasing incidence of invasive aspergillosis in hematopoietic stem cell transplant recipients Marr et al. Clin Infect Dis 2002; 34:909

32. What tests do we have to identify moulds? • morphology • microscopy • additional tests • molecular methods Experience!

33. Aspergillus • Wide spectrum of disease – dependent on immune status • Allergic bronchopulmonary aspergillosis • Pulmonary aspergilloma • Invasive aspergillosis Can be a secondary pathogen in cases of carcinoma or TB

34. Aspergillus fumigatus complex most common cause of aspergillosis~90% of cases

35. Aspergillus niger complex Common cause of ear infections

36. Aspergillus terreus complex Cause of superficial, eye, ear and systemic infections

37. Aspergillus flavus complex Cause of pulmonary and sinus infections

38. In vitro susceptibility of filamentous fungi ITR VOR POS AMB 5FC CASP FLU Asp. fumigatus++ ++ ++ ++ +/- ++ - Asp. niger++ ++ ++ ++ - ++- Asp. terreus++ ++ ++ --++- Asp. flavus++ ++ ++ ++ - ++-

39. Azole resistance in A. fumigatus complex Itraconazole • recent literature 0 - 5% • 7% RMLM 1992 – 2007 (n = 519) • significant increase in resistance since 2004 – now 13% Itraconazole resistant isolates • 58% cross-resistant to voriconazole • 66% cross-resistant to posaconazole Data from Dr Susan Howard

40. Azole cross resistance of Asp. fumigatus complex MIC mg/L Mosquera & Denning. Antimicrob Agents Chemother 2002; 46:556

41. Other Aspergilli Klich MA. Identification of common Aspergillus species (2002). CBS.

42. Non-Aspergillus moulds

43. Increasing frequency of non-Aspergillus mould infections in hematopoietic stem cell transplant recipients Marr et al. Clin Infect Dis 2002; 34:909

44. Fusarium spp. Range of disease from cutaneous through to disseminated infection

45. Scedosporium spp. Can cause subcutaneous infections but dissemination may occur in immunocompromised host

46. Mucorales Cunninghamella Rhizomucor Rhizopus Absidia Mucor etc…

47. In vitro susceptibility of filamentous fungi ITR VOR POS AMB 5FC CASP FLU Asp. fumigatus++ ++ ++ ++ +/- ++ - Asp. niger++ ++ ++ ++ - ++- Asp. terreus++ ++ ++ --++- Asp. flavus++ ++ ++ ++ - ++- Fusarium-++/-+/- --- Scedosporium+/-++/-- -+/-- Mucorales- - ++- --

48. Phialophora Wangiella Paecilomyces Cladophialophora Alternaria Others… Acremonium Penicillium Plus many more…

49. Take time to ‘know’ the fungus in your hospital…. Better the devil….