Disappointing dipstick screening for urinary tract infection in hospital inpatients.

AIM: To compare the performance of leucocyte esterase and nitrite dipstick tests with microscopic examination and culture of first morning urines (n = 420) of hospital inpatients. RESULTS: The sensitivity, specificity, and negative predictive value of the leucocyte esterase test for the cutoff of > 10 WBC/microliter were 57%, 94%, and 68%, respectively. For > 5 WBC per high power field (HPF) these variables were 84%, 90%, and 93%. For > 10(5) colony counts/ml, the sensitivity of the nitrite test was 27%, specificity 94%, and negative predictive value 87%. When either leucocyte esterase or nitrite positivity was accepted as a marker of urinary tract infection, the sensitivity was 78%, specificity 75%, and negative predictive value 94%, and there were 22% false negative results. Semiquantitative microscopic estimation of bacteria per HPF yielded 40% false positives. CONCLUSIONS: Leucocyte esterase and nitrite dipstick tests are not suitable for screening for urinary tract infections.

Origin and transmission of methicillin-resistant Staphylococcus aureus in an endemic situation: differences between geriatric and intensive-care patients.

Imported vs. hospital-acquisition of MRSA was assessed in > 6000 patients at a large tertiary care teaching hospital. About five percent (5.1%) of patients carried MRSA on admission, mostly without clinical symptoms; the highest percentage (11.6%) being in geriatric patients. Hospital-acquisition of MRSA occurred in 1.7% of patients and was particularly high in intensive-care units (5.2%). Phenotype and genotype analysis of 158 MRSA strains isolated from 61 patients revealed a cluster of closely related strains in the hospital-acquired MRSA infections and the close relationship of this cluster to the regional epidemic MRSA strain. The MRSA strains imported by geriatric patients were genetically different, did not spread between geriatric patients and were only a minor source of nosocomial infection.