Antimicrobial susceptibility of clinical isolates of gram-negative bacilli.

No one can doubt the increased incidence of gram-negative bacillary infections and the importance of an awareness of this increase. Today's hospital, where one finds aggressive surgery, patients with multiple indwelling polyethylene lines and Foley catheters, and widespread use of prophylactic antibiotics, serves as a haven for resistant gram-negative bacilli. Twenty-five strains of Escherichia coli, Klebsiella sp, Enterobacter sp, Pseudomonas sp, indole-negative Proteus sp, indole-positive Proteus sp, and Serratia sp from hospitalized patients were tested for susceptibility to eight commonly used antibiotics using an inocula replicating method. Gentamicin proved to be the most effective antibiotic against the majority; most strains were inhibited by 3.12mug/ml or less. Other antibiotics, although not so active against all species, were effective against selected species.