Alicja Rokosz, Katarzyna Kot, Agnieszka Bednarska, Mirosław Łuczak
- Katedra i Zakład Mikrobiologii Lekarskiej AM w Warszawie
- Introduction. Bacterial urinary tract infections (UTI) are the most common clinical type of infections in adult hospitalized patients. They constitute from 40% to 50% of all infections found in this group of patients. Cases of UTI in patients are frequently associated with catheter use. Nosocomial bacterial uropathogens may be resistant to many groups of antibiotics/chemotherapeutics used in urological practice. UTI therapy in hospitalized patients should be guided. It is important to determine drug susceptibility and mechanisms of resistance to antibacterial agents in nosocomial uropathogenic strains.
- Objectives. The aim of performed studies was to isolate, identify and determine drug susceptibility of bacterial uropathogenic strains infecting patients hospitalized in two wards of the Central Clinical Hospital of the Medical University of Warsaw during two years.
- Materials and methods. A total number of 3171 urine samples from patients of the Hematology Department 4D and the Internal Medicine and Nephrology Department 6D were obtained for examinations. Urine samples were collected using transport-growth medium (Uromedium). Bacteriological analyses were continued in cases of significant bacteriuria. Identification of uropathogenic strains was performed in the automatic ATB Expression system (bioMerieux sa). Susceptibility of strains to antibacterial agents was determined with the use of disc diffusion method. Strains of methicillin-resistant (MR) staphylococci, high-level aminoglycoside-resistant (HLAR) enterococci and Gram-negative rods producing extended-spectrum beta-lactamases (ESBL) were detected by means of special tests. Resistance and intermediate susceptibility of Gram-negative rods to carbapenems were confirmed by Etest (AB Biodisk, Sweden).
- Results. During two years a total number of 2126 urine samples was obtained from patients of the Hematology Department 4D. The number of positive specimens was 496 (23.3%). From patients of the Internal Medicine and Nephrology Department 6D - 1045 urine samples were collected, in this number 356 samples (34.1%) were positive. Uropathogenic Escherichia coli (UPEC) strains dominated in cases of UTI in patients of these two wards (415/ 886 strains, 48%), although decreasing contribution of strains of this species to the etiology of nosocomial UTI was observed. Next, strains of the genera Enterobacter, Proteus and Pseudomonas were isolated. Among Gram-positive bacteria (90 strains) enterococci (45 strains, first of all Enterococcus faecalis strains) and staphylococci (45 strains, first of all Staphylococcus haemolyticus strains) dominated. Using special tests 48.9% of MR staphylococci, 66.7% of HLAR enterococci and 6.2% of ESBL - producing Gram - negative rods were detected. Nitrofurantoin was the most active in vitro agent against E. coli, enterococcal and staphylococcal strains. Carbapenems (imipenem, meropenem) and cefepime were the most active against rods from the genera Enterobacter and Proteus. P. aeruginosa strains were susceptible first of all to carbapenem antibiotics.
- Conclusions. Continuous monitoring of bacterial strains causing nosocomial urinary tract infections and their susceptibility to antimicrobial agents is necessary, considering changes that occur. These changes concern the species of uropathogenic strains and their drug susceptibility.