Screening Tests for Asymptomatic Bacteriuria in Pregnant Women

Asymptomatic bacteriuria (ASB) in pregnant women leads to complications like pyelonephritis, preeclampsia, prematurity, low birth weight, and intrauterine death. The present study was undertaken to evaluate screening methods with quantitative culture. Midstream clean catch urine collected from 750 asymptomatic antenatal women were subjected to wet mount, Gram stain, catalase test and triphenyl tetrazolium chloride test (TTC). Cultures were put-up by standard loop method and pour-plate method. Isolates with significant growth were identified by standard methods and antibiotic susceptibility test was done by Kirby- Bauer disc diffusion method. ASB was detected in 7.87% of antenatal women. Among the rapid screening methods, catalase test showed the highest sensitivity (100%), followed by Gram stain (98.30%), TTC test (95.45%) and wet mount (27.12%). Wet mount and Gram stain showed highest specificity (100%), followed by TTC test (98.24%) and catalase test (94.73%). Semi- quantitative culture by standard loop method showed a sensitivity of 96.61% and specificity of 100%. Escherichia coli was the predominant organism isolated (66.66%) and majority of isolates were found sensitive to nitrofurantoin (70%). Gram stain can be a reliable rapid screening method and standard loop method, an adequate substitute for pour plate method.