Effectiveness of Griess Nitrite Test on Screening Asymptomatic Bacteriuria in Pregnancy: A Cross Sectional Study in Harare, Zimbabwe

Abstract

Aim: The aim of this study was to evaluate effectiveness of the Griess test on screening asymptomatic bacteriuria when compared to culture. Study Design: This study was conducted using the cross sectional study design. Place and Duration of Study: The study was conducted at four Harare Primary Care Clinics. The University of Zimbabwe, Nursing Science Department and Medical Microbiology Laboratory were also used.  Methodology: Pregnant women reporting at four purposively selected Primary Care clinics in Harare for registration for antenatal care at gestation between 6 and 22 weeks were randomly selected. Women who were unwilling to participate and declined to provide a signed consent were excluded. Mid-stream clean catch urine samples were collected and tested first by Griess nitrite test followed by culture. Presence of more than 103 colony forming units per milliliter of urine of a similar bacteria was considered positive for asymptomatic bacteriuria. Sensitivity, specificity, positive predictive value and negative predictive value was calculated for the Griess test. Data was analyzed using the Statistical Package for Social Sciences Statistics version 20. Results: Seventeen out of 80 participants we recruited had asymptomatic bacteriuria. The prevalence of asymptomatic bacteriuria in this study was 21.3% (95% CI, 13.5 to 31.8). The sensitivity (100%), specificity (93.7%), positive predictive value (81%) and negative predictive value (100%) of the Griess test were high. Coagulase negative staphylococcus was the popularly (47%) isolated uropathogen, followed by Escherichia coli (29%). Conclusion: The Griess nitrite test was very effective to detect asymptomatic bacteriuria. The Griess test should be considered for screening asymptomatic bacteriuria in pregnancy especially in low resource settings. The culture test should be reserved for positive sample for quantifying bacteria. This is expected to reduce the burden of culture test which is unaffordable especially in low resource settings.