Katarzyna Kot, Alicja Rokosz, Marta Wróblewska, Anna Sawicka-Grzelak, Robert Tomasz Kuthan, Iwona Serafin, Mirosław Łuczak
- Katedra i Zakład Mikrobiologii Lekarskiej AM w Warszawie
- Introduction. Urinary tract infections (UTI) are the most frequently found infections in patients during hospitalisation. They cause severe complications i. e. bacteraemia, inflammatory states of kidneys or renal failure, urosepsis and septic shock. The results of these complications may be longer stay in a hospital and rise of treatment costs. The most important risk factor of UTI, including mixed infections, is catheterization of a bladder. Urinary tract infections of mixed aetiology contribute to dissemination of multiresistant strains. The knowledge of bacterial and fungal microflora involved in these infections and it's susceptibility to antimicrobials is necessary to apply a proper therapy of UTI in hospitalized patients.
- Objectives. Analysis of occurrence and susceptibility to antimicrobial agents of bacterial and fungal strains causing mixed urinary tract infections (UTI) in hospitalized patients.
- Materials and methods. Urine samples were collected by the ,,middle stream" method or by the catheter from hospitalized patients during twelve months. The samples containing at least two strains of different uropathogenic species (each in significant number) were analysed. Biochemical identification of strains was done in automatic ATB Expression system (bioMerieux, sa). Antimicrobial susceptibility testing was performed using ATB UR5 strips and disc diffusion method according to CLSI (reviously NCCLS) recommendations. The standard disc diffusion microbiological procedures were used to detect mechanisms of bacterial resistance to antimicrobials: Gram-negative rods producing extended-spectrum beta-lactamases (ESBL), HLAR enterococci (high-level aminoglycoside resistant) and methicillin-resistant (MR) staphylococci. Resistance of enterococci to glycopeptides (GRE) was confirmed by Etest (AB Biodisk, Sweden).
- Results. The total number of 7352 urine specimens were collected, out of which 2069 (28.1%) were positive in culture and in 363 cases (17.1%) mixed bacterial or bacterial and fungal microflora were isolated. Seven hundred and sixteen bacterial strains were cultured. Gram-negative bacteria (485 strains; 67.7%) predominated, especially Escherichia coli (175 strains). Enterococci (211 strains) prevailed in a group of Gram-positive bacteria (231 strains; 32.3%). Most commonly co - cultured in mixed infections were enterococci and Gram-negative rods (54.3% of urine samples). 76.3% of enterococcal strains were resistant to glycopeptides (GRE). Four methicillin-reistant staphylococcal strains (4/7) were found. Among Gram-negative rods 9.2% ESBL-positive strains were detected. Fungal strains belonging to the genus Candida and the species Trichosporon asahii were also isolated. The most active antimicrobials against Gram-negative rods were imipenem, nitrofurantoin, fosfomycin and fluoroquinolones. Enterococcal and staphylococcal strains were susceptible first of all to vancomycin, teicoplanin, nitrofurantoin and fosfomycin.
- Conclusions. Enterococcus faecalis and E. coli strains dominated in urinary tract infections of mixed aetiology in hospitalized patients. During treatment of these infections the possibility of appearance of enterococcal and GRE strains, staphylococcal MR strains and Gram-negative ESBL-producing rods should be taken into consideration.