Frequency and sensitivity pattern of Extended Spectrum beta Lactamase producing isolates in a tertiary care hospital laboratory of Pakistan.

OBJECTIVE To determine frequency, distribution and sensitivity pattern of Extended-Spectrum beta Lactamase (EBSL) producing organism at a tertiary care hospital in Pakistan. METHODS All members of enterobacteriacae isolated between April and August 2002 were studied. Isolates were speciated according to standard biochemical tests. Susceptibility testing was performed by Kirby-Bauer method. ESBL was detected using double disc method using cefotaxime versus cefotaxime plus clavulanate according to NCCLS. Statistical analysis was performed by SPSS version 10. Test of significance were calculated using chi-square test. RESULTS During the study period, 1137/2840 (40%) of the isolates tested were found to be ESBL producing. ESBL positivity was detected in 50% Enterobacter sp., 41% E. coli and 36% K. pneumoniae. ESBL production was noted in 52% of nosocomial isolates tested (415/799). ESBL was more frequent in patients at the extremes of ages (under 5 years and more than 60 years). Cross-resistance to non-beta lactam antibiotics (flouoroquinolones, aminoglycosides and co-trimoxazole) was also more frequent in ESBL producing organisms (p<0.05). CONCLUSION A high frequency of ESBL positivity amongst our isolates is documented which is alarming in low-income settings where expensive second line agents are unavailable. Our data supports urgent need for regular screening and surveillance for these organisms.