Detection of Neisseria gonorrhoeae and Chlamydia trachomatis colonization of the gravid cervix

OBJECTIVES: The aims of the study were to determine whether a Gram stain of cervical mucus can accurately rule out infection with Neisseria gonorrhoea e or Chlamydia trachomatis and to compare a diagnostic test that is based o n the polymerase chain reaction with a deoxyribonucleic acid probe in the d etection of these organisms. STUDY DESIGN: Gravid patients were screened for N gonorrhoeae and C trachom atis with a deoxyribonucleic acid probe, Gram stain, and analysis with the polymerase chain reaction. A normal, noninfected sample was defined by <10 polymorphonuclear leukocytes per high-power field on the Gram stain. Standa rd statistical methods were used to compare results of the Gram stain and t he deoxyribonucleic acid probe, as well as to compare results of deoxyribon ucleic acid probe hybridization and polymerase chain reaction analysis. A P value of < .05 was considered statistically significant. RESULTS: Patient enrollment totaled 519. The prevalence of infection as det ermined by deoxyribonucleic acid probe hybridization was 1.4% for N gonorrh oeae (7/518) and 6.8% for C trachomatis (35/518). The cervical Gram stain p redicted the absence of infection in 17% (90/518) of patients, with a negat ive predictive value of 99% for N gonorrhoeae and 97% for C trachomatis. Af rican American race, age <20 years, and unmarried status were all predictor s of the presence of C trachomatis or N gonorrhoeae cervicitis. For the pat ients who lacked these risk factors (n = 74), the Gram stain had 100% negat ive predictive value. Analysis with the polymerase chain reaction detected 8 additional patients with C trachomatis and 105 additional patients with N gonorrhoeae, in comparison with deoxyribonucleic acid probe hybridization. CONCLUSION: The cervical Gram stain can accurately predict the absence of N gonorrhoeae and C trachomatis in gravid women. Analysis with the polymeras e chain reaction indicates that N gonorrhoeae and C trachomatis are signifi cantly more prevalent in this population than previously reported.