Extended Spectrum beta-lactamases in pyogenic gram-negative bacilli

ABSTRACT

To determine the frequency, distribution and sensitivity pattern of extended spectrum beta-lactamases producing Gram-negative bacilli from pus samples. Cross Sectional Comparative Study Study, place and duration This study was conducted at the Microbiology Department, Fauji Foundation Hospital, Rawalpindi over a period of two years from 04/ 2004 to 03 / 2006 Inclusion criteria All pus samples were included. Exclusion criteria Dried pus swabs were not included in the study. Multidrug resistance and ESBLs-production were studied in a total of 138 Enteric Gram-negative Rods [GNR] obtained from pus specimens by the help of double disc diffusion technique. Susceptibility testing was done to various groups of antimicrobials. Frequency of ESBLs-production was 56.5%. ESBLs-positivity was highest at 61-70 years of age group [24.3%], followed by 11-20 yrs [17.5%]. ESBLs-positivity in females versus males was 58.2% 54.2% and highest in indoor patients [92.3%]. ESBLs-production was highest amongst Escherichia coli [55.1%] followed by Klebsiella pneumoniae, [29.5%], Pseudomonas aeruginosa [9.0%], Aeromonas spp [2.6%]. The antibiotics showing best activity against ESBLs-producing K pneumoniae and E coli were beta lactam beta -lactamase inhibitors [piperacillin /tazobactam 100% and 80%-] and carbapenems [imipenem 100% each and meropenem 75% and 100%] respectively. ESBLs producing GNRs had a more antibiotic-resistant profile than non- ESBLs producers. They were not only resistant to beta-lactams but showed cross-resistance towards a wide variety of commonly used other antimicrobials. ESBLs producers are more resistant as compared to non-ESBLs producers. Considering the high prevalence of ESBLs in Enteric Gram-negative rods, it is suggested that all such isolates should be tested for the production of ESBLs in the routine microbiology laboratory