In vitro susceptibility of bacterial isolates from patients with respiratory tract infections to beta-lactam antibiotics

In vitro susceptibilities of bacterial pathogens to beta-lactam antibiotics were determined. Bacterial pathogens examined included various isolates from the patients of respiratory tract infections at the hospitals of Kyoto-Shiga area in 1981 and 1983. Major organisms isolated from clinical specimens were Haemophilus spp., Klebsiella spp., Pseudomonas spp., S. aureus and Streptococcus spp. An increase in the isolation frequency of P. aeruginosa, a decrease in the isolation frequency of H. influenzae and no change in the isolation frequency of the other organisms were observed between the years 1981 and 1983. Data from susceptibility tests of clinical isolates confirmed that cefazolin (CEZ) and cefotiam (CTM) showed good antibacterial activity against S. aureus and cefmenoxime (CMX) was highly effective on Streptococcus spp., but that the susceptibilities of both organisms to CEZ, CTM, and cefmetazole (CMZ) in 1983 were lower than in 1981. Although CMX also showed good antibacterial activity against Klebsiella spp., there were no changes in the effectiveness of CTM, CMZ, and CEZ between the years 1981 and 1983. The in vitro antibacterial activities of CMX and cefoperazone against Haemophilus spp. were superior to those of the other beta-lactams tested, but there was a decline in the efficacy for CEZ. Although cefsulodin and piperacillin were highly active against Pseudomonas spp., declines in their effectiveness was observed between the years 1981 and 1983.