Molecular Epidemiology of Pseudomonas aeruginosa in the Intensive Care Units - A Review

D S Blanc,G Zanetti,P Francioli

doi:10.2174/1874285800701010008

Abstract

Pseudomonas aeruginosa is one of the leading nosocomial pathogens in intensive care units (ICU). This opportunist pathogen is commonly recovered from moist environments, and is also found colonizing 2.6 to 24% of hospitalized patients. We reviewed the recent literature that used highly discriminatory typing methods to precisely identify the reservoirs and modes of transmission of this microorganism in the ICU setting. In most ICUs, the endogenous flora was suspected to be the main source of infection compared to exogenous sources (other patients, the contaminated environment such as sinks or taps). However, the percentage of endogenous versus exogenous sources might vary considerably from one setting to another. Reasons for this include the compliance of health care workers to infection control measures, the contamination of the environment, and probably also the biology of the pathogen (intrinsic fitness factors). As P. aerugi-nosa is ubiquitous in the environment and colonizes up to 15% of hospitalized patients, eradication of the reservoir is difficult, if not impossible. Therefore, efforts should primarily focus on reinforcement of infection control measures to limit its transmission.

Highlights

Pseudomonas aeruginosa is an ubiquitous environmental bacterium with minimal requirements for survival and a remarkable ability to adapt to a variety of environmental challenges
A recent prospective investigation over a 40-week period showed that tap water from faucets contaminated with P. aeruginosa played a crucial role (42% of patients infected with P. aeruginosa in clinical specimens) in the propagation of this pathogen to intensive care units (ICU) patients, and to patients from other adjacent wards, through patient-to-patient transmissions [20]
The situation resolved when chlorine disinfection of sinks was reinforced. Review of all these molecular investigations on the epidemiology of P. aeruginosa in the ICU setting shows that the contribution of endogenous versus exogenous reservoirs to the colonization and infection of patients varies according to the compliance of health care workers to infection control measures, to the contamination of the environment, and probably to the biology of the pathogen (Fig. 1)

Summary

INTRODUCTION

Pseudomonas aeruginosa is an ubiquitous environmental bacterium with minimal requirements for survival and a remarkable ability to adapt to a variety of environmental challenges. In one of the first studies that investigated this topic, a German team prospectively searched for P. aeruginosa in patients, staff members and environment during a 4-month period in a surgical ICU [7,8] They found a low number of patients with P. aeruginosa (18/153, 12%), most of which were colonized by a unique genotype, suggesting endogenous colonization (only 2 possible transmissions from patient to patient were suspected). A recent prospective investigation over a 40-week period showed that tap water from faucets contaminated with P. aeruginosa played a crucial role (42% of patients infected with P. aeruginosa in clinical specimens) in the propagation of this pathogen to ICU patients, and to patients from other adjacent wards, through patient-to-patient transmissions [20]. The situation resolved when chlorine disinfection of sinks was reinforced

CONCLUSIONS

Findings

Pseudomonas aeruginosa Outbreak in a Burn Unit