ABSTRACT
INTRODUÇÃO E OBJETIVO: A resistência bacteriana é problema frequente e importante no ambiente nosocomial. Nesse contexto, várias bactérias apresentam habilidade de desenvolver mecanismos de resistência enzimáticos, destacando-se as Enterobacteriaceae. Nesta família de microrganismos, a produção de Klebsiella pneumoniae carbapenemase (KPC) é um mecanismo emergente, o que justifica sua vigilância constante. MATERIAL E MÉTODO: Este trabalho pesquisou o fenótipo de KPC em 30 isolados clínicos de enterobactérias resistentes a cefalosporinas de terceira geração e sensibilidade diminuída a carbapenem oriundas de dois hospitais (em Porto Alegre e na Grande Porto Alegre, RS). Realizou-se discodifusão com imipenem, meropenem e ertapenem, e 14 cepas com halo < 22 mm para o último antimicrobiano foram submetidas ao teste de Hodge modificado. RESULTADOS: Nenhuma amostra apresentou carbapenemase (Hodge negativo). DISCUSSÃO: Apesar de não ter sido detectada carbapenemase, a resistência aos carbapenens possivelmente pode ser atribuída à presença de betalactamases cromossômicas (AmpC) e/ ou de amplo espectro (ESBL) associada à alteração de permeabilidade nos canais de porina. CONCLUSÃO: Considerando o caráter emergente da KPC, torna-se importante seu rastreamento em isolados de enterobactérias com sensibilidade diminuída ao ertapenem.
INTRODUCTION AND OBJECTIVE: Bacterial resistance is a frequent and important problem in the nosocomial environment. In this context, several bacteria have the ability to develop mechanisms of enzymatic resistance, mainly Enterobacteriaceae. In this family of microorganisms, the production of Klebsiella pneumoniae carbapenemase (KPC) is an emerging mechanism, which should be under constant observation. MATERIAL AND METHOD: This study investigated the phenotype of KPC in 30 clinical isolates of Enterobacteriaceae resistant to third generation cephalosporin and carbapenem from two hospitals (Porto Alegre city and Porto Alegre, RS). It was performed disk diffusion method with imipenem, meropenem and ertapenem. Additionally, 14 strains with halo < 22 mm for the last antimicrobial agent underwent modified Hodge test. RESULTS: No sample showed carbapenemase (Hodge negative). DISCUSSION: Despite the fact there was no carbapenemase, resistance to carbapenems is possibly attributed to the presence of beta-lactamases AmpC and/or ESBL associated with changes in the permeability of porin channels. CONCLUSION: Given the emerging nature of KPC, it is important to trace it in Enterobacteriaceae isolates with decreased susceptibility to ertapenem.
Subject(s)
beta-Lactamases , Enterobacteriaceae/enzymology , Enterobacteriaceae/isolation & purification , Cross Infection/enzymology , Klebsiella pneumoniae/enzymology , Klebsiella pneumoniae/isolation & purification , Drug Resistance, MicrobialABSTRACT
Extended spectrum beta-lactamases [ESBLs] represent a major group of lactamases currently being identified in large number worldwide mostly produced by gram-negative bacteria. The present study was done to see the frequency of ESBLs in gram-negative bacterial isolates causing nosocomial wound infections from a tertiary care hospital in Bangladesh. A total of 125 wound swabs were collected from surgical site infections and burn cases, admitted in Rajshahi Medical College Hospital [RMCH], during January to June, 2008. Swabs were cultured for aerobic bacteria and antimicrobial susceptibility testing was carried out using the Kirby-Bauer agar diffusion method. Gram-negative isolates were tested for ESBLs on Mueller Hinton agar by both modified double disc and phenotypic confirmatory methods. Culture yielded 71 [56.8%] bacterial growths with 60 [84.51%] gram-negative and 11 [15.49%] gram-positive bacteria [Staph aureus]. Gram-negative isolates included 23 [32.39%] E. coli, 19 [26.76%] Klebsiella spp., 16 [22.54%] Pseudomonas spp., and 02 [2.82%] Proteus spp. The number of ESBL producing bacteria in modified double disc and phenotypic confirmatory methods were 28 [46.67%] and 25 [41.66%] respectively. Highest rate of ESBLs was observed in Klebsiella spp. [57.89%] followed by Proteus spp. [50.0%], E. coli [47.83%] and Pseudomonas spp. [31.25%], which showed significantly increasing resistance to 3rd generation cephalosporins, aminoglycoside, quinolone and trimethoprim-sulfamethoxazole. Significant number of nosocomial wound infections is caused by ESBL bacteria; those are not detected by routine antimicrobial susceptibility testing. It is recommended that clinical microbiology laboratory should take urgent measure for ESBLs detection as routine to enhance hospital infection control programme
Subject(s)
Humans , Cross Infection/enzymology , Gram-Negative Bacterial Infections/enzymology , Wound Infection/microbiology , Wound Infection/enzymology , Microbial Sensitivity TestsABSTRACT
Staphylococcus aureus (n=84) isolated from the nostrils of a healthy population from Kathmandu and from the infectious cases (n=100) from Tribhuvan University Teaching Hospital, Kathmandu, Nepal were tested from May 1996 to March 1997 in Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal by microbiological and chemical methods to find out their beta lactamase activity. Among the healthy population, in domiciliary conditions 21.4% of the isolates were found beta lactamase producers. The occurrence of beta lactamase producing S. aureus was greater among female (27.0%) than among male (17.0%), however it was not significant (X2 = 1.2309, P > 0.05). The occurrence of the same was observed high among 40 and above age groups (66.7%) and 0-9 age group (60.0%), however no association with any particular age group was observed (X2 = 16.8674, P > 0.05). The b lactamase activity of S. aureus hospital inpatients isolates was 75.0% showing high occurrence of b lactamase activity in hospital isolates compared to S. aureus isolates from healthy carriers (X2 = 52.4113, P < 0.001). No association of beta lactamase positive hospital isolates with gender (X2 = 0.2158, P > 0.05) and age group (X2 = 1.5522, P > 0.05) was observed. This study shows that the prevalence of beta lactamase positive S. aureus was greater in hospital cases than in nasal carriers in domiciliary condition indicating the requisition of further study in this field.