A Comparative Study of the Direct Gram Staining Method and The Standard Wire Loop Culture Method for Screening of Significant Bacteriuria.

Abstract

This study attempts to compare the sensitivity of the culture method to the direct Gram staining method in the screening of significant bacteriuria. A total of 100 subjects comprised of 60 adult females, 25 adult males, 8 male children and 7 female children were screened for significant bacteriuria by the direct Gram’s staining method and culture methods. In the culture method, an uncentrifuged urine sample was inoculated on Cysteine Lactose Electrolyte Deficient (CLED) agar and blood agar using a standard wire loop of 0.01mL,
incubated at 37 0 C for 18 to 24 hours. The direct Gram staining was carried out by plating 0.01mL of centrifuged urine sample on a clean glass slide allowing it to air dry, stained by the Gram’s method and under ×100 objective lens. Of the 100 uncentrifuged urine samples processed by culture method, 21(21%) were positive for significant bacteriuria, this includes 7 adult males, 12 adult females, 1 female child and 1 male child. Escherichia coli and Pseudomonas spp were the most frequently isolated organisms with 8 of 21 (38.1%) each, followed by Klebsiella spp 3 of 21 (14.3%), and 2 of 21(9.5%) were Staphylococci aureus. In the direct Gram staining method, 18(18%) were positive for significant bacteriuria; including 7 adult males, 10 adult females 1 female child. Statistical analysis showed no significant difference in the sensitivity pattern of both methods in the diagnosis of UTIs (p>0.05). Though urine culture remains the best diagnostic procedure for the detection of UTIs, the direct Gram’s staining method is also effective, and may be used in an emergency situation or where there are no facilities for culture to screen for significant bacteriuria.