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

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Presentation on theme: "Identification, Susceptibility & Resistance Dr Caroline B. Moore Mycology Reference Centre University Hospital of South Manchester The University of Manchester."— Presentation transcript:

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 Chromagar How do we identify yeasts? Culture morphology

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

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

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

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

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 flucytosine 6% fluconazole 1.2% 5% of C. albicans with reduced susceptibility

18 Candida parapsilosis, Candida orthopsilosis, Candida metapsilosis 2 nd 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 Candida parapsilosis complex

19 C.parapsilosis FLU ITR VOR POS AMB 5FC CASP Rates of resistance seen in our laboratory fluconazole 0.4%

20 3 rd or 4 th 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 Candida glabrata

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

22 Candida tropicalis Usually 4 th 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 C.tropicalis FLU ITR VOR POS AMB 5FC CASP Rates of resistance seen in our laboratory flucytosine 20% fluconazole 46%

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

25 May be a breakthrough species Always fluconazole resistant and amphotericin intermediate Candida krusei 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 Combination therapy generally used Crypto. neoformans FLU ITR VOR POS AMB 5FC CASP Cryptococcus neoformans

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

29 Species of…. Trichosporon Geotrichum Blastoschizomyces 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 Allergic bronchopulmonary aspergillosis Pulmonary aspergilloma Invasive aspergillosis Can be a secondary pathogen in cases of carcinoma or TB Wide spectrum of disease – dependent on immune status

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 Asp. flavus Asp. fumigatus /-++ - ITR VOR POS AMB 5FC CASPFLU Asp. niger Asp. terreus

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 MIC mg/L Azole cross resistance of Asp. fumigatus complex 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 Asp. flavus Asp. fumigatus /-++ - ITR VOR POS AMB 5FC CASPFLU Asp. niger Asp. terreus Fusarium - + +/- +/ Mucorales Scedosporium +/-+ +/ /- -

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

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


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