Syed Abdul Mujeeb  ( Blood Transfusion Services, Karachi. )
Syed Ali Jaffer Naqvi  ( Department of Nephrourology, Jinnah Postgraduate Medical Centre, Karachi. )
Syed Iqbal Ahmed  ( Jinnah Postgraduate Medical Centre and The Lab, Karachi )

Urinary tract infection (UTI). a common ailment in children, women and elderly people is associated with pyuria, bacteriuria and nitriteuria^1,2 . Its diagnosis, based on urine culture with significant bacteriuria, needs a good microbio­logical laboratory and trained microbiologist. Such facility is only available in urban areas of developing countries. There­fore, for rural areas, a simple and cost effective test is needed for rapid screening and referral of cases of UTI for culture and sensitivity test. This study was undertaken to determine the sensitivity, specificity, positive (PPV) and negative predictive value (NPV) of pyuria, bacteriuria and nitriteuria individually and in combination by using urine culture as a gold standard in order to assess their use for initial screening of urinary tract infection.

One hundred midstream specimens of urine were cultured on SLED media, using 5mmwireloop, for bacteriuria at the Kidney Centre, Karachi. Urine was also examined for pus cells per high power field (PHF); bacteria by Gram staining of centrifuged urine and nitriteuria using multistrips (Bayer Diagnostics). Sensitivity, specificity, PPV and NPV of the test were calculated according to the method described by Galen and Gambino⁴. Out of 100 urinary samples cultured on CLED media, 25 yielded significant growth (Table).

Nitriteuria detected in 20%, pyuria in 72% and bacteriuria in 84% of all cases of urinary tract infection. While combination of these tests identified all cases of urinary tract infections, i.e., 100%. In combination pyuria, bacteriuria and nitriteuria showed 100% sensitivity, 72% specificity, 46% PPV and 100% NPV. To test 100% sensitivity and NPV of bacteriuria, pyuria and nitriteuria, 50 symptomatic and 50 asymptomatic cases, having no bacteriuria, pyuria or nitriteuria were selected. Theirurine specimen were cultured on CLED media, but none of them showed significant growth proving the reliability of the test for initial screening of urine.

Observations of this study suggest that in the areas with no facilities for microbial culture urine may initially be screened for UTI. Only positive urine samples for pyuria, bacteriuria and nitrite urine should be sent to referral centres for culture and sensitivity. This procedure can also be used as most cost effective technique for rapid exclusion of UT! in urban areas as well.

Services of administrator and staff of TKC namely Mr. Sarwar Kanial, Ms Zulekha Ghaffar, Mr Sohail Iqbal and Mr. Khawaja Mustafa are highly acknowledged.

1. Ahmed, S.I. Antibacterial sensitivity pattern in urinary tract infection. J.Pak.Med.Assoc., 1983;:69-71.
2. Cheesbrough, M. Medical laboratory manual for tropical countries. IIed Shire, ELBS Tropical Health Technology, Cambridge, 1987, pp. 146 47.
3. Kasa, RH. Asymptomatic infections of the urinary tract. Trans.Assoc.Am. Physicians. 1956;69:56-64.
4. Mynahan, C. Evaluation of microscopic urinalysis as a screening procedure. Lab. Medicine, 1984;15:176-79.