Comparison of microbiological methods for the diagnosis of urinary tract infections

In this study, urine culture is the gold standard diagnosis of urinary tract infections compared with gram stain, leukocyte count with thoma slide, nitrite test and leukocyte esterase tests activity for rapid and reliable diagnosis of urinary tract infection. In addition prevalence, antibiotic resistance profile and extended-spectrum beta-lactamase (ESBL) ratio was determined of the microorganisms cause urinary tract infection. Effects of the some pedispozan factors on the incidence of urinary tract infection were investigated.This study was performed in Duzce University, Faculty of Medicine, Department of Medical Microbiology between May 2010-November 2010. In our study, 658 urine samples were included to the study sent from the patients with symptoms urinary tract infection applied to polyclinics and clinics. Microorganisms were isolated using the conventional culture methods and API identification systems and Kirby-Bauer disk diffusion method was used for identification of the bacteria and to assess antibiotic susceptibility.Cultures were found positive in 137 (21.7 %) samples and 143 (21.7 %) cultures were evaluated as contamination. Escherichia coli was found as the most common isolated bacteria (67.2 %) in cultures. ESBL production was found in 19 % of Gram-negative bacteria. The frequency of urinary tract infection was found 32.9 % in diabetic patients; 16 % in pregnant women, and 31.4 % in 66 years and over patients. The sensitivity of Gram stain was found 82.2 %, specificity 96.8 %, false positivity 32 %, false negativity 17.8 %. The rates was determined respectively for leukocyte count with thoma slide, 40.1 %, 95.8 %, 18.5 %, 21.2 %; for nitrite test; 40.1 %, 95.8 %, 42 %, 59.9 %; and for leukocyte esterase test, 88.1 %, 34.1 %, 65.9 %, 11.9 %.Gram stain was found to be the most suitable method of rapid diagnosis of urinary tract infection compared to other diagnostic methods. a very high sensitivity and specificity, false positive and false negative rates were low and the easy applicability. Because of advanced age, diabetes and pregnancy were predisposing factors to urinary tract infection; follow-up and treatment should be done on a regular basis.