Evaluation of dipstrips, direct gram stain and pyuria as screening tests for the detection of bacteriuria

Two hundred and fifty cases of clinically suspected urinary tract infection were analysed for the detection of bacteriuria. Parameters studied included direct Gram staining, pyuria on microscopic examination of uncentrifuged urine and dip strip method for the detection of blood, protein, nitrite and leucocyte esterase. Significant bacteriuria (colony count 10(5) per ml) was found in 112 cases with a positivity ranging from 65 to 83% for the presence of blood, protein, nitrite and leucocyte esterase. Highest positive predictive values were obtained with the presence of nitrite and leucocyte esterase (98%), blood, protein and nitrite (94%) as well as with blood, protein, nitrite and leucocyte esterase (98%). Both pyuria and direct Gram staining were positive in 85% cases. The combined presence of both these parameters gave 100% positive predictive value. Gram staining combined with pyuria was more effective and economical as compared to the dipstrips for the detection of bacteriuria.