Hospital environment as reservoir of Pseudomonas aeruginosa in human cases: a molecular epidemiology investigation in a hospital setting in central Italy

Pseudomonas aeruginosa is one of the main causes of hospital infections that are difficult to manage because of multidrug resistance (MDR). The aim of this study was to describe a molecular investigation on 19 clinical and 14 isolates from the environment in the Hub hospital of the Molise region, central Italy. Antimicrobial susceptibility was evaluated using BD Phoenix (TM) Automated Microbiology System. Pulsed-field gel electrophoresis (PFGE) with SpeI, enterobacterial repetitive intergenic consensus (ERIC-PCR), and random amplified polymorphic DNA-PCR were performed for genotyping. All 33 P. aeruginosa showed MDR phenotype. PFGE had 0.99 discriminatory power, underlining high heterogeneity among the strains. The genetic relatedness between two human isolates (H12 and H15) from neonatal intensive care (NICU) and one environmental strain (E1) collected from siphon of sink in the delivery room was noticeable, as well as between one strain from faucet in NICU (E2) and siphon sink (E5) from delivery room. The link between H12, H15, and E1 strains was corroborated by ERIC-PCR showing epidemiological concordance, although with a lower discriminatory power. The study findings strengthened the critical correlation between clinical P. aeruginosa and environment, according to previous molecular surveys on outbreaks occurred in Italy.