[Gram-negative bacteria in a medical resuscitation unit. Distribution of species and antibiotic sensitivity]

The distribution of Gram-negative bacilli species and their susceptibility to various antibiotics were surveyed over a 18-month period in an intensive care unit. Gram-negative bacilli were isolated from blood cultures (65), urine cultures (191), respiratory tract samples (176) or miscellaneous samples (69). The bacilli most frequently isolated from blood cultures were enterobacteriaceae (95%), including Escherichia coli (46%), Proteus (22%) and Klebsiella pneumoniae (12%). Pseudomonas aeruginosa was predominant in respiratory tract samples, and Serratia marcescens was more frequently isolated from urine cultures than from other samples. Antibiotic susceptibility testing was performed using a standard disc diffusion method. In view of the susceptibility of blood isolates to the second-generation cephalosporins we consider that these are preferable to third-generation cephalosporins for first-line antibiotic therapy of septicaemia due to Gram-negative bacilli, except for hospital-acquired infections. More than 50% of the bacilli were resistant to ampicillin; ticarcillin and mezlocillin were not very active against Klebsiella. Nalidixic acid was very active on urine isolates and therefore seems to be a good first-line antibacterial for lower urinary tract infections.