In vivo selection of resistant Enterococcus hirae with altered PBPs during ampicillin treatment

MASSA R; MOLLERACH M; BANTAR C; MICUCCI M; SMAYEVSKY J; ROVEGNO A; GUTKIND G

Las Vegas, USA

Congreso; 94th General Meeting of the American Society for Microbiology; 1994

American Society for microbiology

After ten days of ampicillin treatment (1.5 g/daily the Enterococcus hirae responsible for an urinary infection in a male patient with prostatic hypertrophy changed their MICs of penicillin G from 1 to 4 mg/L, imipenem from <0,5 to 4 mg/L and ampicillin from <0,5 to 4 mg/L. 125I- Penicillin X in vivo labelled microorganisms showed after solubilization and SDS-PAGE, a very significative increase in the amount of a PBP2 like peptide with a low affinity for imipenem, and a reduced amount of PBPs 3 and 4 in the resistant strain as compared with the original sensitive isolate. The increase of PBP2 was so high that a band could be seen in Coomasie Blue stained gels as a very major protein. I- Penicillin X in vivo labelled microorganisms showed after solubilization and SDS-PAGE, a very significative increase in the amount of a PBP2 like peptide with a low affinity for imipenem, and a reduced amount of PBPs 3 and 4 in the resistant strain as compared with the original sensitive isolate. The increase of PBP2 was so high that a band could be seen in Coomasie Blue stained gels as a very major protein. The radiotracer allowed, due to its high specific activity, to detect all PBPs in short (15 minutes) incubation times. The patient was finally treated with nitrofurantoin, which rendered urine cultures negative.