In Vitro Antimicrobial Activities of β-Lactams, Aminoglycosides, Quinolones, Glycopeptides and Trimethoprim-Sulfamethoxazole Against Gram-Negative and Gram-Positive Bacteria Isolated from Patients with Intraabdominal Infections

Abstract

Objective To determine the in vitro activity of β-Lactams Aminoglycosides, fluoroquinolones, glycopeptides, and trimethoprim-sulfamethoxazole against Gram-negative and Gram-positive organisms isolated from patients with intraabdominal infections

Design Observational study from 1999 to 2000

Setting Surgery wards

Results Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Bacteroides fragilis, Enterococcus faecium, Proteus mirabilis, Enterobacter cloacae, Klebsiella pneumoniae and Citrobacter freundii were the most frequently isolated organisms (Tab. 1). The activities of antimicrobial agents were species dependent. Of Staphylococcus aureus 50% were a methicillin resistant strain. For enterococci, ampicillin resistance was significantly more prevalent for Enterococcus faecium than for E. faecalis. One strain of E. faecalis resistant to vancomycin was isolated.

Among Gram-negative rods, β-lactams activity varied considerably. Overall meropenem, ceftazidime, piperacillin and piperacillin-tazobactam had the broadest spectrum of activity against all bacteria except Stenotrophomonas maltophilia isolates. Ciprofloxacin was active against most Gram-negative bacteria, but was inactive against most strains of Acinetobacter calcoaceticus-baumanni complex and S.maltophilia. In vitro both amikacin and gentamycin were active against most species, amikacin was always more active than gentamycin. Trimethoprim-sulphamethoxazole was active against most Enterobacteriaceae, but was inactive against most strains of P.aeruginosa, P. mirabilis and Acinetobacter spp.

Conclusions Data documenting antibiotic susceptibility against the most frequent isolates organisms that can cause infections are reviewed here. In our study many pathogens responsible for intraabdominal infections were resistant to many antimicrobial agents used for therapy. These problems underline the need for continued and timely surveillance of resistance among bacteria responsible for surgical infections. The selection of the most effective therapy minimizes the risk of surgical site infection.