Characterization of penicillin-resistant<i>Streptococcus faecium</i>mutants

Abstract

The characteristics of three spontaneous mutants of Streptococcus faecium PS which overproduce the penicillin-binding protein (PBP) 5 and are resistant to penicillin were investigated and compared with those of the parent. The mutants grew a little more slowly than the parent, had a smaller cellular size, did not grow as filaments in the presence of penicillin minimal inhibitory concentration (MIC), and were significantly more prone to autolysis. The relationship between the characteristics of the mutants and the overproduction of PBP 5 is discussed.