IN VITRO COMPARATIVE EFFICACY OF CARBAPENEMS AND β-LACTAM β-LACTAMASE INHIBITOR COMBINATIONS AGAINST MULTI DRUG RESISTANT GRAM NEGATIVE BACILLI

Background: gram-negative bacilli are commonly encountered in hospitalized and community acquired infections. exposure to a wide range of antibiotics has led to multidrug resistant strains. carbapenems and β-lactam β-lactamase inhibitor combinations are commonly used groups in such clinical settings. this study was conducted to find out susceptibility of multidrug resistant gram-negative bacilli to these antimicrobials. material & methods: this descriptive study was conducted at microbiology department, fauji foundation hospital, rawalpindi, from april 2004 to march 2006. sensitivity pattern of 2413 gram-negative rods was tested. results: from 4204 samples, 2413(57.39%) gram-negative rods were isolated. these were escherichia coli 1039(43.0%), pseudomonas aeruginosa 667(27.6%), klebsiella pneumoniae 490(20.3%), proteus 62(2.6%), acinetobacter 40(1.7%), providencia 35(1.5%) and enterobacter 34(1.4%). to imipenem, 1.5% klebsiella pneumoniae, 3.2% escherichia coli, 11% enterobacter 15%, proteus mirabilis, 10.7% pseudomonas aeruginosa and 20% acinetobacter, while none of providencia. were resistant. to piperacillin/tazobactam, 0.69% klebsiella pneumoniae, 2.38% proteus mirabilis, 7.5% escherichhia coli & pseudomonas aeruginosa, 20% acinetobacter while none of enterobacter & providencia were resistant. to meropenem only 7.9% pseudomonas aeruginosa were resistant. none of klebsiella pneumoniae and escherichia coli were resistant to it. to cefoperazone/sulbactam, 20% klebsiella pneumoniae were resistant but none of escherichia coli, enterobacter, proteus mirabillis, pseudomonas aeroginosa, providencia and acinetobacter were resistant. conclusion: resistance pattern of carbapenems and β-lactam, β-lactamase inhibitor combinations shows that both these groups of antibiotics are effective in treating serious life threatening infections caused by gram-negative bacilli