Evaluación del desempeño diagnóstico del medio de difusión en agar Etest® para el estudio de sensibilidad a los antifúngicos

Raquel Ballesté; Zaida Arteta; Ana Barloco; Nora Fernández; Nélida Mousqués; Beatriz Xavier; María José Cabrera; Ana Combol; Elbio Gezuele

Authors

Raquel Ballesté Universidad de la República, Facultad de Medicina, Hospital de Clínicas, Departamento de Laboratorio Clínico, Prof. Adj. Instituto de Higiene, Departamento de Parasitología y Micología, Prof Adj. Médico Parasitólogo. Médico Especialista en Laboratorio de Patología Clínica
Zaida Arteta Universidad de la República, Facultad de Medicina, Hospital de Clínicas, Clínica Médica A, Asistente. Instituto de Higiene, Departamento de Parasitología y Micología, Asistente. Especialista en Medicina Interna
Ana Barloco Universidad de la República, Facultad de Medicina, Hospital de Clínicas, Departamento de Laboratorio Clínico, Asistente. Especialista en Laboratorio Clínico
Nora Fernández Universidad de la República, Facultad de Medicina, Hospital de Clínicas, Departamento de Laboratorio Clínico, Asistente. Instituto de Higiene, Departamento de Parasitología y Micología., Asistente. Médico Parasitólogo
Nélida Mousqués Universidad de la República, Facultad de Medicina, Instituto de Higiene, Departamento de Parasitología y Micología, Ayudantes. Médicos
Beatriz Xavier Médico Parasitólogo
María José Cabrera Universidad de la República, Facultad de Medicina, Instituto de Higiene, Departamento de Parasitología y Micología, Ayudantes. Médicos
Ana Combol Licenciada en Laboratorio Clínico
Elbio Gezuele Universidad de la República, Facultad de Medicina, Instituto de Higiene, Departamento de Parasitología y Micología, Prof. Agdo. Médico Parasitólogo

Keywords:

RESISTANCE TO ANTIFUNGAL DRUGS, AGAR, IMMUNODIFUSION, MICROBIAL SENSITIVITY TESTS

Abstract

The increase of the incidence of mycosis has led to develop new techniques to study in vitro antifungal susceptibility.
In this study, Agar Etest –the most used method of agar dilution in our country– was compared to the reference method –broth microdilution method– and the MICs for both techniques were correlated.
Eighty Candida spp. strains were studied using Etest and broth microdilution method (Protocol M27-A2 del National Committee for Clinical Laboratory Standards [NCCLS]).
Amphotericin B (AB), itraconazol (ITZ) and fluconazole (FLZ) were tested. Etest diagnostic performance was compared to the reference method (EPIDAT, version 2.0 for Windows); correlation was calculated using Pearson’s correlation coefficients.
Etest specificity and sensitivity for ITZ were 44% and 92% respectively, positive predictive value (VPP) was 60% and negative predictive value (VPN) 85%.
Specificity and sensitivity for FLZ were 85% and 12.5% respectively, VPP was 45% and VPN 49%. For AB, Etest did not detect resistant strains. Predictive values were calculated to detect resistance using NCCLS breakpoints. correlation coefficients were as follow: r = - 0,02 (AB), r = - 0,03 (FLZ) y r = 0,4 (ITZ).
The method was not validated since there was no correlation between MICs obtained by Etest and those obtained by the reference technique. According to the findings, diagnostic performance of the technique was not reliable. Global performance of Etest seems to be unreliable for clinical tests.

References

1) Wenzel RP, Pfaller MA. Candida species: emerging hospital bloodstream pathogens. Infect Control Hosp Epidemiol 1991, 12(9): 523-4.
2) Fox JL. Fungal infections rates are increasing. ASM 1993; 59: 515-8.
3) Salonen J, Nikoskelainen J. Lethal infections in patients with hematological malignancies. Eur J Haematol 1993; 51(2): 102-8.
4) Arteaga Hernández E, Capó de Paz V, Pérez Fernández-Terán ML. Micosis oportunistas invasivas en el SIDA: un estudio de 211 autopsias. Rev Iberoam Micol 1998; 15: 33-5.
5) Musial CE, Cockerill FR 3rd, Roberts GD. Fungal infections of the immunocompromised host: clinical and laboratory aspects. Clin Microbiol Rev 1988; 1(4): 349-64.
6) Diekema DJ, Messer SA, Brueggemann AB, Coffman SL, Doren GV, Herwaldt LA, et al. Epidemiology of candidemia: 3-year. Results from de emerging infections and epidemiology of Iowa organisms study. J Clin Microbiol 2002; 40(4): 1298-302.
7) Winston DJ, Emmanouilides C, Busuttil RW. Infections in liver transplant recipients. Clin Infect Dis 1995; 21(5): 1077-91.
8) Anaissie E, Bodey GP. Nosocomial fungal infections: old problems and new challenges. Infect Dis Clin North Am 1989; 3(4): 867-82.
9) Anaissie E, Bodey GP, Rinaldi MG. Emerging fungal pathogens. Eur J Clin Microbiol Infect Dis 1989; 8(4): 323-30.
10) Fraser VJ, Jones M, Dunkel J, Storfer S, Medoff G, Dunagan WC. Candidemia in a tertiary care hospital: epidemiology, risk factors, and predictors of mortality. Clin Infect Dis 1992; 15(3): 414-21.
11) Bodey GP. The emergence of fungi as major hospital pathogens. J Hosp Infect 1988; 11(Suppl A): 411-26.
12) Trick WE, Jarvis WR. Epidemiology of nosocomial fungal infection in the 1990s. Rev Iberoam Micol 1998; 15: 2-6.
13) Fisher-Hoch SP, Hutwagner L. Opportunistic candidiasis: an epidemic of the 1980s. Clin Infect Dis 1995; 21(4): 897-904.
14) Pfaller MA, Diekema DJ. Role of sentinel surveillance of candidemia: trends in species distribution and antifungal susceptibility. J Clin Microbiol 2002; 40(10): 3551-7.
15) Wingard JR. Importance of Candida species other than C. albicans as pathogens in oncology patients. Clin Infect Dis 1995; 20(1): 115-25.
16) Weems JJ, Chamberland ME, Ward J, Willy M, Padhye AA, Solomon SL. Candida parapsilosis fungemia associated with parenteral nutrition and contaminated blood pressure transducers. J Clin Microbiol 1987; 25(6): 1029-32.
17) Ghannoum MA, Rice LB. Antifungal agents: mode of action, mechanisms of resistance, and correlation of these mechanisms with bacterial resistance. Clin Microbiol Rev 1999; 12(4): 501-17.
18) White TC, Marr KA, Bowden RA. Clinical, cellular and molecular factors that contribute to antifungal drug resistance. Clin Microbiol Rev 1998; 11(2): 382-402.
19) Mahayni R, Vázquez JA, Zervos MJ. Nosocomial candidiasis: epidemiology and drug resistance. Infect Agents Dis 1995; 4(4): 248-53.
20) Lebowitz LD, Ashbee HR, Evans EG, Chong Y, Mallatova N, Zaidi M, et al. A two year global evaluation of the susceptibility of Candida species to fluconazole by disk diffusion. Diagn Microbiol Infect Dis 2001; 4(1-2): 27-33.
21) Durán MT, Velasco D, Canle D, Moure R, Villanueva R. Susceptibilidad antifúngica de aislados de Candida spp. de hemocultivos en un período de 5 años (1997-2001). Enferm Infecc Microbiol Clin 2003; 21(9): 488-92.
22) Pfaller MA, Jones RN, Messer SA, Edmond MB, Wenzel RP. National surveillance of nosocomial blood stream infection due to species of Candida other than Candida albicans: frequency of occurrence and antifungal susceptibility in the SCOPE program, SCOPE Participant Group. Surveillance and control of pathogens of epidemiologic. Diagn Microbiol Infect Dis 1998; 30(2): 121-9.
23) Pfaller MA, Jones RN, Doern GV, Sader HS, Hollis RJ, Messer SA. International surveillance of bloodstreams infections due to Candida species: frequency of occurrence and antifungal susceptibilities of isolates collected in 1997 in the United States, Canada, and South America for SENTRY Program. J Clin Microbiol 1998; 36(7): 1886-9.
24) Nguyen MH, Peacock JE Jr, Morris AJ, Tanner DC, Nguyen ML, Snydman DR, et al. The changing face of candidemia: emergence of non–Candida albicans species and antifungal resistance. Am J Med 1996; 100(6): 617-23.
25) Powderly WC, Kobayashi GS, Herzig GP, Medoff G. Amphotericin B-resistant yeast infection in severely immunocompromised patients. Am J Med 1988; 84(5): 826-32.
26) Nguyen MH, Clancy CJ, Yu VL, Yu YC, Morris AJ, Snydman DR, et al. Do in vitro susceptibility data predict the microbiologic response to amphotericin B? Results of a prospective study of patients with Candida fungemia. J Infect Dis 1998; 177(2): 425-30.
27) Ballesté R, Arteta Z, Mousqués N, Xavier B, Cabrera MJ, González M, et al. Antifungal susceptibility in Candida strains isolated of oral cavity of positive HIV patients. World STI/AIDS Congress, 8. Punta del Este, Uruguay December 2-5, 2003.
28) Ballesté R, Arteta Z, Mousqués N, Xavier B, Cabrera MJ, Gezuele E. Opportunistic Mycosis on HIV-AIDS Patients. World STI/AIDS Congress, 8. Punta del Este, Uruguay. December 2-5, 2003.
29) Rieppi G, Ballesté R, López L, Arteta Z. Candidemias en Centro de Terapia Intensiva. Tratamiento, seguimiento, pronóstico y susceptbilidad a los antifúngicos. Congreso Uruguayo de Medicina Interna, 9. Montevideo, Uruguay. 2003.
30) Steinbach WJ, Perfect JR. Newer antifungal therapy for emerging fungal pathogens. Int J Infect Dis 2003; 7(1): 5-20.
31) Sobel JD, Vázquez J. Candidiasis in the intensive care unit. Seminars in respiratory and critical care medicine 2003; 24(1): 99-111.
32) National Commitee for Clinical Laboratory Standards. Reference method for broth dilution antifungal susceptibility testing of yeast. Appoved Standard. Document M27-A. Pensilvania: National Commitee for Clinical Laboratory Standards, 1997.
33) National Commitee for Clinical Laboratory Standards. Reference method for broth dilution antifungal susceptibility of yeast. Approved Standarard. Document M27-A2. Pensilvania: National Commitee for Clinical Laboratory Standards, 2002.
34) Pfaller M, Viishnu CH, Espinel-Ingroff A. Reference method for broth dilution antifungal susceptibility testing of filamentous fungi. NCCLS document M38-A. Approved Standard. Pensilvania: Nationa Committee for Laboratory Standars, 2000.
35) Vandenbossche I, Vaneechoutte M, Vandevenne M, De Baere T, Verschraegen G. Susceptibility testing of fluconazol by the NCCLS broth macrodilution method, E-Test, and disk diffusion for application in the routine laboratory. J Clin Microbiol 2002; 40(3): 918-21.
36) AB BIODISK. Etest Technical guide 4b: Antifungal susceptibility testing of yeasts. Piscataway, New Jersey: AB BIODISK, 1994.
37) Colombo AL, Barchiesi F, McGough DA, Fothergill AW, Rinaldi MG. Evaluation of the E test system versus a microtitre broth method for antifungal susceptibility testing of yeasts against fluconazole and itraconazole. J Antimicrob Chemother 1995; 36(1): 93-100.
38) Dannaoui E, Colin S, Pichot J, Piens MA. Evaluation of the Etest for fluconazole susceptibility testing of Candida albicans isolated from oropharyngeal candidiasis. Eur J Clin Microbiol Infect Dis 1997; 16(3): 228-32.
39) Clancy C, Nguyen MH. Correlation between in vitro susceptibility determined by Etest and response to therapy with amphotericin B: results from a multicenter prospective study of candidemia. Antimicrob Agents Chemother 1999; 43(5): 1289-90.
40) Kwon-Chung K, JE. B. Medical Mycology. Philadelphia: Lea & Febiger, 1992.