[Occurrence of alert pathogens in hospital environment Part II. Multidrug-resistant non-fermenting bacilli].

Introduction: Multidrug-resistant gram-negative non-fermenting bacilli are an important cause of nosocomial infection. Aim of this study was to analyze the prevalence and antimicrobial susceptibility of rods of the species Acinetobacter baumannii and Pseudomonas aeruginosa, belonging to multidrug-resistant alert pathogens.

Methods: 105 (70%) strains of A. baumannii and 46 (30%) strains of P. aeruginosa were isolated from 125 patients hospitalized in the Specialistic Hospital in Krakow, in the years 2008-2010. Taken into account first isolate from the patient. The condition for inclusion in the study was the resistance or reduced susceptibility to selected groups of antibiotics, such as beta-lactams, aminoglycosides and fluoroquinolones. Bacterial identification and antimicrobial susceptibility testing were performed by automated system Vitek 2 Compact (bioMerieux, Poland). All strains were tested with phenotypic method Etest MBL (AB Biodisk, Sweden) for the presence of resistance mechanism associated with the production of metallo-beta-lactamases.

Results: Bacilli of the species A. baumannii were isolated most frequently from patients from the Department of Anesthesiology and Intensive Care (52%) and Burn Therapy Unit (25%), with clinical materials collected from the respiratory tract (51%), the wound swabs (18%), urine (11%) and blood (11%). Production of metallo-beta-lactamases was found in 24 (22.9%) strains of A. baumannii. Drugs effective against multidrug-resistant isolates of A. baumannii were colistin and amikacin. Department of anesthesiology and intensive care (59%) and unit of internal medicine (11%) were the main source of multidrug-resistant strains of P. aeruginosa. Pathogens were mainly isolated from clinical specimens collected from the respiratory tract (61%), urine (15%) and wound swabs (13%). Seven (15.2%) strains of P. aeruginosa produced the metallo-beta-lactamases. With regard to colistin and piperacillin with tazobactam was noted the highest percentage of susceptible isolates.

Conclusions: MDR bacteria belonging to alert pathogens are an important cause of many severe and difficult to treat infections which greatly increases the morbidity and mortality among hospitalized patients worldwide. Epidemiological studies and detection of local resistance patterns can provide useful information which can be used in the development of strategies to combat the rising tide of microbial antibiotic resistance.