In Vitro Comparative Efficacy of Carbapenems and β-Lactam β-Lactamase Inhibitor Combinations Against Multi Drug Resistant Gram Negative Bacilli

S Mumtaz, M Ahmad, I Aftab, N Akhtar, A Hameed


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.

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