Optimization of a rapid diagnostic test for detection of group B streptococcus from antepartum patients

• Published in: Diagnostic microbiology and infectious disease Vol. 73; no. 3; pp. 236 - 238
• Main Authors: Faro, Jonathan P., Bishop, Karen, Riddle, Gerald, Katz, Allan, Faro, Sebastian
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.07.2012; Elsevier
• Subjects: bacitracin; Bacteriological Techniques - methods; Bacteriology; Biological and medical sciences; Colonization; confidence interval; cross reaction; Cross Reactions; Diagnostic Tests, Routine - methods; Enterococcus; Female; Fundamental and applied biological sciences. Psychology; Group B streptococcus; Humans; Infectious Disease; Infectious diseases; Internal Medicine; Medical sciences; Microbiology; Miscellaneous; patients; Pregnancy; Pregnancy Complications - diagnosis; Pregnancy Complications - microbiology; Rapid detection; Rectum - microbiology; Sensitivity; Sensitivity and Specificity; Specificity; Streptococcal Infections - diagnosis; Streptococcal Infections - microbiology; Streptococcus; Streptococcus agalactiae; Streptococcus agalactiae - isolation & purification; Vagina - microbiology; Sensitivity; Specificity; Rapid detection; Group B streptococcus; Colonization; Human; Optimization; Infection; Streptococcaceae; Rapid technique; Streptococcus B; Bacteria; Micrococcales
• ISSN: 0732-8893; 1879-0070; 1879-0070
• DOI: 10.1016/j.diagmicrobio.2012.03.015

We analyzed the performance of a new rapid diagnostic test for use in determining group B streptococcus colonization in pregnancy. Vaginal–rectal specimens were compared by the rapid test, a commercial laboratory culture result, and an in-house culture. Of 150 patient samples, 72 were positive by the rapid test, giving a prevalence of 48.0% versus 24.7% by traditional culture. Characterization of these results showed cross-reactivity with Enterococcus. The addition of bacitracin reduced this interference, and when reanalyzed, a colonization rate of 31.3% was found (P = 0.3961, chi-square), as well as a sensitivity of 100% (95% confidence interval [CI] 89.1–100) and a specificity of 93.6% (95% CI 86.9–97.2). The addition of bacitracin greatly improves the reliability of this diagnostic test and demonstrates a novel approach to reduce interference. An accurate determination of the test's sensitivity and specificity, however, awaits enrollment of the remaining subjects.