Susceptibility of gram-negative bacterial isolates to six β-lactam and two aminoglycoside antibiotics at our University Hospital

Abstract

Susceptibilities of Gram-negative bacterial strains isolated at the University Hospital in 1987 to six β-Lactam antibiotics (azthreonam, cefmetazole, ceftizoxime, lactamoxef, aminobenzyl-penicillin and piperacillin) and two aminoglycoside antibiotics (gentamicin and amikacin) were examined by agar dilution and the agar diffusion method. Results obtained from both methods correlated well in most of the strains. Most of the strains belonging to Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae and Proteus mirabilis were sensitive in the β-lactam antibiotics except aminobenzyl-penicillin and piperacillin. They were also sensitive to aminoglycoside antibiotics. Most strains of Citrobacter freundii, Enterobacter cloacae and Serratia marcescens were sensitive to azthreonam, lactamoxef and aminoglycosides, but were less sensitive to other β-lactams. Acinetobacter calcoaceticus was generally resistant to β-lactams except ceftizoxime, but was sensitive to aminoglycosides. More than half of the strains of Pseudomonas aeruginosa were sensitive to azthreonam, piperacillin and aminoglycoside antibiotics and only lactamoxef was active in Pseudomonas maltophilia.