In vitro activity of aztreonam against gram negative bacteria from clinical specimens and its comparison with other commonly used antibiotics

Abstract

A total of 755 gram negative bacteria isolated from clinical specimens were tested against aztreonam by the disc agar diffusion test. The strains of bacteria used in this study consisted of Escherichia coli (314), Enterobacter aerogenes (30), E. agglomerans (7), E. cloacae, (39), Citrobacter diversus (9), C. freundii (13), Hafnia alvei (3), Acinetobacter calcoaceticus (10), Klebsiella oxytoca (6), K. ozaenae (5), K. pneumoniae (107), Morganella morganii (3), Moraxella sp. (10), Pasteurella multocida (1), Proteus mirabilis (66), P. vulgaris (4), Providencia rettgeri (12), P. stuartii (5), Pseudomonas aeruginosa (85), P. fluorescens (2), P. maltophila (7), Salmonella sp. (1) and Serratia marcescens (17). In vitro activity against aztreonam was compared with amikacin, ampicillin, carbenicillin, cephalosporin, cefoxitin, chloramphenicol, gentamicin, nitrofurantoin, piperacillin, tetracycline, sulfamethoxazole-trimethoprim and tobramycin. Over 99% of E. coli and Enterobacter species were susceptible to aztreonam. All the 118 strains of Klebsiella, 87 strains of Proteus-Providencia and 17 strains of S. marcescens were also susceptible. Aztreonam also showed good activity against P. aeruginosa, inhibiting 90% of the 85 isolates tested.