Molecular Biological Analysis of Metallo-β-lactamase-producing Acinetobacter baumannii Isolated from 4 Children in the NICU and Environmental Investigation

Acinetobacter spp. Is one of the major bacteria strains causing ventilator-associated nosocomial infection. Emergence of antimicrobial resistant Acinetobacter strain has occurred, and patients undergoing chemotherapy or immature infant may suffer significant impacts from A. baumannii. A. Baumannii which produces metallo-β-lactamase (MBL-producing A. Baumannii) were detected from 4 infants in our NICU. We suspected nosocomial infections based on pulsed-field gel electrophoresis (PFGE), but no MBL-producing A. Baumannii were detected by three NICU environmental investigations conducted by the ICT. However, MBL-producing A. Baumannii was isolated in the ventilator circuit and environment around the water supply system in the NICU. On the other hand, examination of a tracheal tube, obtained from a patient with MBL-producing A. Baumannii isolated from the endotracheal aspirates, detected only non-MBL-producing A. Baumannii, suggesting that two PFGE strains originated from the same homologies. If nosocomial-infection due to antimicrobial-resistant microbes is suspected, the presence of different susceptible strains of bacteria should be considered.