Avaliação comparativa de distintos métodos fenotípicos para a detecção de cepas produtoras de carbapenemases

• Autor(a) principal: Moura, Jhonatha Rodrigo Cordeiro de [UNIFESP]
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=3748968; http://repositorio.unifesp.br/handle/11600/46397
• topic: Carbapenens; Oxacilinases; Bacilos gram-negativos; Ágar macconkey; Blue-carba; Carba np; Carbapenens; Oxacilinases; Bacilos gram-negativos; Ágar macconkey; Blue-carba; Carba np

During the last decade, it has been observed the rapid development of antimicrobial resistance among clinical isolates of Enterobacteriaceae, Pseudomonas spp., and Acinetobacter spp. worldwide. The production of ?-lactamases is the most important mechanism of resistance in Gram-negative bacilli, being the carbapenemases the most versatile mechanisms of carbapenem resistance. These enzymes have broad spectrum of activity, making difficult the selection of adequate antimicrobial therapy. Furthermore, genes encoding ?-lactamases are highly transmissible. Objective: This study aimed to evaluate the performance of five phenotypic methods for detection of carbapenemase-producing Gram-negative bacilli. Methods: Strains previously characterized were pulled out from the LEMC/ALERTA bank of microorganisms. The confirmation of carbapenemase production was performed by ertapenem hydrolysis using MALDI-TOF MS. The phenotypic tests evaluated were: Hodge modified test, ANVISA Technical Note 01/2013, Carba NP and its modification, CarbAcineto NP, Blue-Carba, CarbapenemBac, and CarbapenemBac Metallo. Results: Although the specificity rates of the ANVISA Technical Note and MHT were 100%, the Technical Note (97.3%) showed higher sensitivity rate than that of the MHT (88.5%) for carbapenemase detection. The Carba NP, Blue-Carba and CarbapenemBac tests showed high sensitivity and specificity rates (100%) when colonies subcultured on Mueller-Hinton agar were tested. The sensitivity and specificity rates of Carba NP (98.6 and 100%), BlueCarba (97.1 and 91%) and CarbapenemBac (96.5 and 100%) were slightly lower when bacterial colonies were obtained from blood agar. On the other hand, the sensitivity rates of Carba NP (71.1%) and Blue-carba (68.9%) were unacceptable when colonies obtained from MacConkey agar were evaluated. However, the sensitivity of CarbapenemBac (97.3% sensitivity) was less affected by the MacConkey agar. Conclusions: We conclude that 1. The colorimetric methods showed excellent sensitivity and specificity for carbapenemases detection when bacterial colonies were subcultured on Mueller-Hinton agar or blood agar; 2. Bacteria colonies subcultured on MacConkey agar must not be utilized for colorimetric tests, except for CarbapenemBac, which showed a good sensitivity and specificity rates for detection of carbapenemases independently of the culture medium used to subculture the bacterial isolate.