The modified Hodge test is a useful tool for ruling out klebsiella pneumoniae carbapenemase

OBJECTIVE: Enterobacteriaceae bacteria harboring Klebsiella pneumoniae carbapenemase are a serious worldwide threat. The molecular identification of these pathogens is not routine in Brazilian hospitals, and a rapid phenotypic screening test is desirable. This study aims to evaluate the modified Hodge test as a phenotypic screening test for Klebsiella pneumoniae carbapenemase. METHOD: From April 2009 to July 2011, all Enterobacteriaceae bacteria that were not susceptible to ertapenem according to Vitek2 analysis were analyzed with the modified Hodge test. All positive isolates and a random subset of negative isolates were also assayed for the presence of blaKPC. Isolates that were positive in modified Hodge tests were sub-classified as true-positives (E. coli touched the ertapenem disk) or inconclusive (distortion of the inhibition zone of E. coli, but growth did not reach the ertapenem disk). Negative results were defined as samples with no distortion of the inhibition zone around the ertapenem disk. RESULTS: Among the 1521 isolates of Enterobacteriaceae bacteria that were not susceptible to ertapenem, 30% were positive for blaKPC, and 35% were positive according to the modified Hodge test (81% specificity). Under the proposed sub-classification, true positives showed a 98% agreement with the blaKPC results. The negative predictive value of the modified Hodge test for detection was 100%. KPC producers showed high antimicrobial resistance rates, but 90% and 77% of these isolates were susceptible to aminoglycoside and tigecycline, respectively. CONCLUSION: Standardizing the modified Hodge test interpretation may improve the specificity of KPC detection. In this study, negative test results ruled out 100% of the isolates harboring Klebsiella pneumoniae carbapenemase-2. The test may therefore be regarded as a good epidemiological tool.

Persistência do efeito otoprotetor: qual a duração da otoproteção à amicacina?

Há comprovação de que o fenômeno de resistência ocorre quando a dose não lesiva da amicacina protege as células ciliadas contra a ototoxicidade da própria amicacina. OBJETIVO: O objetivo deste trabalho é verificar se o fenômeno de resistência é temporalmente persistente. MÉTODO: Estudo experimental com 14 cobaias albinas (Cavia porcellus) divididas em três grupos. Avaliação da função auditiva por emissões otoacústicas por produto de distorção (EOAPD): na pré-exposição à amicacina, no 15º dia de aplicação da dose não lesiva, no final da aplicação da dose lesiva e antes da decapitação. RESULTADOS: O Grupo A (controle) apresentou função auditiva e padrão histológico normais. No Grupo B (amicacina 20mg/kg/dia intramuscular por 30 dias e dose lesiva (400 mg/kg/dia) por 12 dias) e no Grupo C (mesmo esquema do grupo B, porém mantidos por 60 dias e sacrificados), as OEA-PD confirmaram função auditiva normal no período pré-exposição e manutenção do padrão após dose não lesiva, porém, houve perda importante da função auditiva após término do período de aplicação da dose lesiva. CONCLUSÃO: Não houve manutenção do fenômeno da autodefesa estendida por um período de 30 a 60 dias após a aplicação de doses lesivas de amicacina.

The modified Hodge test is a useful tool for ruling out Klebsiella pneumoniae carbapenemase

OBJECTIVE: Enterobacteriaceae bacteria harboring Klebsiella pneumoniae carbapenemase are a serious worldwide threat. The molecular identification of these pathogens is not routine in Brazilian hospitals, and a rapid phenotypic screening test is desirable. This study aims to evaluate the modified Hodge test as a phenotypic screening test for Klebsiella pneumoniae carbapenemase. METHOD: From April 2009 to July 2011, all Enterobacteriaceae bacteria that were not susceptible to ertapenem according to Vitek2 analysis were analyzed with the modified Hodge test. All positive isolates and a random subset of negative isolates were also assayed for the presence of blaKPC. Isolates that were positive in modified Hodge tests were sub-classified as true-positives (E. coli touched the ertapenem disk) or inconclusive (distortion of the inhibition zone of E. coli, but growth did not reach the ertapenem disk). Negative results were defined as samples with no distortion of the inhibition zone around the ertapenem disk. RESULTS: Among the 1521 isolates of Enterobacteriaceae bacteria that were not susceptible to ertapenem, 30% were positive for blaKPC, and 35% were positive according to the modified Hodge test (81% specificity). Under the proposed sub-classification, true positives showed a 98% agreement with the blaKPC results. The negative predictive value of the modified Hodge test for detection was 100%. KPC producers showed high antimicrobial resistance rates, but 90% and 77% of these isolates were susceptible to aminoglycoside and tigecycline, respectively. CONCLUSION: Standardizing the modified Hodge test interpretation may improve the specificity of KPC detection. In this study, negative test results ruled out 100% of the isolates harboring Klebsiella pneumoniae carbapenemase 2. The test may therefore be regarded as a good epidemiological tool.