Avaliação comparativa da acurácia de diferentes testes fenotípicos para a detecção de amostras produtoras de metalo-beta-lactamsaes
Arquivos
Data
2007
Autores
Picão, Renata Cristina 
Orientadores
Gales, Ana Cristina
Tipo
Dissertação de mestrado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Objetivo: Avaliar a acuracia de diferentes testes fenotipicos para a deteccao da producao de MBL entre amostras produtoras de IMP, VIM, SPM, GIM, ou SIM, incluindo Pseudomonas, Acinetobacter spp. e enterobacterias. Metodos: Foram testadas 46 bacterias nao relacionadas geneticamente e produtoras de diferentes tipos de MBL. Dezenove amostras nao produtoras de MBL foram incluidas como controles negativos. Foi avaliada a capacidade do inibidor de MBL (IMBL) em inibir o crescimento bacteriano e em realizar a hidrolise do substrato. Os isolados foram submetidos aos testes de disco aproximacao e disco combinado para adeteccao da producao de MBL, utilizando imipenem e ceftazidima em combinacao com diferentes IMBLs. Resultados: Foi obtido 100 por cento de sensibilidade e especificidade para a deteccao da producao de MBL por disco aproximacao utilizando acido mercaptopropionico como IMBL, em combinacao com ceftazidima e imipenem, para P. aeruginosa e Acinetobacter spp., respectivamente. A tecnica de disco combinado utilizando imipenem e EDT A apresentou os mesmos resultados para detectar enterobacterias produtoras de MBL, considerando-se como ponto de corte o aumento de pelo menos 5,0 mm na zona de inibicao do crescimento bacteriano. Conclusoes: Nossos resultados indicam que ambos os metodos fenotipicos para a deteccao de MBL, disco aproximacao e disco combinado, devem ser escolhidos apos a identificacao da bacteria-teste. Adicionalmente, devem ser considerados a prevalencia local de bacterias que apresentem este determinante de resistencia, assim como a habilidade de tecnicos especializados em interpretar corretamente a inibicao de MBL
The emergence of metallo-β-lactamase (MBL)-producing isolates is a challenge to routine microbiology laboratories, since there are no standardized methods for detecting such isolates. The aim of this study was to evaluate the accuracy of different phenotypic methods to detect MBL production among Pseudomonas, Acinetobacter spp and enterobacterial isolates, including GIM-, IMP-, SIM-, SPM-, and VIM- variants. A total of 46 genetically unrelated P. aeruginosa, P. putida, Acinetobacter spp. and enterobacterial strains producing distinct MBLs were tested. Nineteen strains were included as negative controls. The inhibition of bacterial growth and β-lactam hydrolysis caused by MBL-inhibitors (IMBL) were also evaluated. The isolates were tested for MBL production by both double disk synergy test (DDST) and combined disk (CD) using imipenem and ceftazidime as substrates in combination with distinct IMBL. One hundred percent sensitivity and specificity was achieved by DDST using 2-mercaptopropionic acid in combination with ceftazidime and imipenem for detection of MBL production among P. aeruginosa and Acinetobacter spp. isolates, respectively. CD showed the same results for detecting MBL-producing enterobacteria by combining imipenem and EDTA with a 5.0 mm breakpoint increase in the inhibition zone. Our results indicate that both phenotypic methods to detect MBL-producing isolates should be based on the genera to be tested regardless of the enzyme produced by such isolates as well as the local prevalence of MBL producers and on the ability of specialized technicians to correctly interpret MBL inhibition.
The emergence of metallo-β-lactamase (MBL)-producing isolates is a challenge to routine microbiology laboratories, since there are no standardized methods for detecting such isolates. The aim of this study was to evaluate the accuracy of different phenotypic methods to detect MBL production among Pseudomonas, Acinetobacter spp and enterobacterial isolates, including GIM-, IMP-, SIM-, SPM-, and VIM- variants. A total of 46 genetically unrelated P. aeruginosa, P. putida, Acinetobacter spp. and enterobacterial strains producing distinct MBLs were tested. Nineteen strains were included as negative controls. The inhibition of bacterial growth and β-lactam hydrolysis caused by MBL-inhibitors (IMBL) were also evaluated. The isolates were tested for MBL production by both double disk synergy test (DDST) and combined disk (CD) using imipenem and ceftazidime as substrates in combination with distinct IMBL. One hundred percent sensitivity and specificity was achieved by DDST using 2-mercaptopropionic acid in combination with ceftazidime and imipenem for detection of MBL production among P. aeruginosa and Acinetobacter spp. isolates, respectively. CD showed the same results for detecting MBL-producing enterobacteria by combining imipenem and EDTA with a 5.0 mm breakpoint increase in the inhibition zone. Our results indicate that both phenotypic methods to detect MBL-producing isolates should be based on the genera to be tested regardless of the enzyme produced by such isolates as well as the local prevalence of MBL producers and on the ability of specialized technicians to correctly interpret MBL inhibition.
Descrição
Citação
PICÃO, Renata Cristina. Avaliação comparativa da acurácia de diferentes testes fenotípicos para a detecção de amostras produtoras de metalo-beta-lactamsaes. 2007. 154 f. Dissertação (Mestrado em Ciências) - Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, 2007.