A rapid method for detection of group B streptococcal colonization: testing at the bedside

Area of Science:

• Microbiology
• Neonatal Health
• Infectious Disease

Background:

• Group B streptococci (GBS) vertical transmission causes early neonatal sepsis.
• Intrapartum antibiotics can prevent GBS transmission.
• Rapid GBS detection methods are needed to target antibiotic use effectively.

Purpose of the Study:

• To evaluate the accuracy of a rapid colorimetric starch serum medium test for detecting GBS colonization.
• To assess the test's performance when interpreted by labor and delivery nurses.
• To compare the rapid test results with routine culture methods.

Main Methods:

• Vaginal and rectal specimens were collected from women with preterm labor or prolonged rupture of membranes.
• A colorimetric starch serum medium test was performed and interpreted by nurses.
• Results were compared to standard bacteriologic cultures.
• Sensitivity and specificity were calculated.

Main Results:

• Nurses identified only 45% of positive vaginal and 44% of positive rectal GBS cultures using the rapid test.
• This sensitivity was significantly lower than the 93% (vaginal) and 95% (rectal) sensitivity achieved by a technologist.
• Test specificity was 95% for nurses.
• Sensitivity was particularly low (53% vaginal, 36% rectal) for mothers with clinically septic infants.

Conclusions:

• The starch serum medium test, as interpreted by nurses, has inadequate sensitivity to replace routine cultures for GBS detection.
• Improving nursing staff interpretation is more critical than modifying the medium itself.
• Further efforts are needed to enhance the accuracy of rapid GBS screening in clinical settings.