Antimicrobial susceptibility and resistance determinants of Clostridium butyricum isolates from preterm infants.

This study reports the antibiotic susceptibility and genetic resistance determinants of 39 Clostridium butyricum strains isolated from the faeces of preterm infants as well as one reference strain. Results showed that all the strains were susceptible to cefoxitin, imipenem, vancomycin, tigecycline, metronidazole, chloramphenicol and linezolid. Resistance was observed to clindamycin (100%), penicillin G, amoxicillin and piperacillin (15%), tetracycline (7.5%) and erythromycin (5%). Investigation of the genetic basis of the observed resistance phenotypes showed that resistance to penicillin was due to β-lactamase activity and that resistance to tetracycline involved tet(O) or tet(O/32/O) homologue genes. Clindamycin and erythromycin resistance may involve another genetic determinant, different from those commonly described for clostridia.