Prevalence of Multidrug-Resistant Pseudomonas aeruginosa and Risk Factors for their Infections at Intensive Care Units of a Tertiary Hospital in Southern China

Pseudomonas aeruginosa (PA) is highly significant opportunistic pathogens causing healthcare associated infections (HAIs) in hospital settings, notably at intensive care units (ICUs). The aim of this study was to retrospectively analyze the infection status, prevalence and antimicrobial resistance (AMR) of PA at ICUs of a tertiary care hospital in southern China during a one-year period (2016) and examine the clinical risk factors for HAIs by PA. Multiple-locus variablenumber tandem-repeat (VNTR) analysis (MLVA) method was employed to analyze clonality of the strains. Our results suggested that the resistance of PA in ICUs were higher than in other wards. In terms of resistance to carbapenems, the resistance gene island (blaOXA-1+blaIMP+ant(2’’)-Ia+aac(6’)-Ib) carried in IntI was a salient feature among AMR genes. While PA infections at local ICUs seemed frequent, there were no obvious trends suggestive of outbreaks. Some epidemic strains have apparently thrived locally for substantial periods, as carriers of major AMR genes and virulence factors. For risk factors for HAIs, inappropriate treatment was found to impact empiric antibiotic therapy of PA infections, especially in the case of carbapenems, where patients often did not get proper treatment during hospitalization of more than 30 days. Multifactor analysis shows that ventilator-associated pneumonia (VAP) was an independent risk factor for increasing the 30-day mortality rate in patients. In addition, the use of antimicrobials, duration of hospitalization and use of mechanical ventilation before isolation were independent risk factors for HAIs.