Genotypic characteristics of Pseudomonas aeruginosa strains circulating in the tertiary referral Children's Medical Hospital in Tehran, Iran

Abstract

Pseudomonas aeruginosa is an important pathogen with the ability to cause infection in all departments of the hospital, especially in intensive care units (ICUs). The aim of this study is to analyse the epidemiological relationships among clinical P. aeruginosa strains isolated from different wards of the Children's Medical Center Hospital (Tehran, Iran). These isolates were identified by standard laboratory procedures and tested for antimicrobial resistance to several antibiotic agents. The genetic similarity of the strains was investigated by amplification of the enterobacterial repetitive intergenic consensus sequence (ERIC-PCR). During the study period, 87 non-duplicate patients were colonised or infected with P. aeruginosa. Among the isolates, resistance to piperacillin/tazobactam was low (27%), followed by amikacin (31%), gentamicin (33%), imipenem (33%), ciprofloxacin (36%) and meropenem (39%). Thirty-five patients (40.2%) were either colonised or infected with a multidrug-resistant P. aeruginosa strain (MDRP) over a one-year period, and 17 isolates were non-susceptible to all the tested antibiotics. One predominant profile (D) was identified in 59 strains. This profile first appeared in the paediatric intensive care unit (PICU) and infection ward in June 2010, and circulated around all wards up to the end of the study period. Of the 35 MDRP, 22 (62.8%) were found to be profile D. Molecular typing of the isolates suggests considerable cross-transmission of P. aeruginosa not only between patients in one ward but also between patients from different wards. This can be explained partly by the high number of patients transferred between different wards of the hospital.