Comparison of laboratory methods in the diagnosis of urinary tract infection.

Three methods of semiquantitative culture and two techniques of microscopy were compared with a surface viable count for the detection of significant bacteriuria in one thousand midstream specimens of urine. The results obtained with the blotting-paper-strip method on MacConkey agar and with Uricult dip-slides correlated well with the results of the surface viable count, and both methods were suitable for routine use. The blotting-paper-strip method was preferred for laboratory use because of expense but dip-slides are useful for general practice and outpatient clinics. Semi-quantitative culture by Microstix dip-strips gave less accurate results, and the nitrite test area detected only a small proportion of infected specimens. The microscopic examination of a Gram-stained film of the centrifuged deposit of urine specimens yielded more useful information and was more reproducible than examination of a wet film of the untreated urine.