VALUE OF SCREENING FOR ORO-PHARYNGEAL CHLAMYDIA-TRACHOMATIS INFECTION

Aims-To determine whether ore-pharyngeal colonisation by Chlamydia tra chomatis occurs in patients at risk of genital chlamydia infection; to determine whether screening pharyngeal specimens by polymerase chain reaction (PCR) increases detection of C trachomatis compared with isol ation and the immune dot blot test; and to correlate the detection of C trachomatis and Neisseria gonorrhoeae in the pharynx with a history of oro-genital contact. Methods-Thirteen homosexuals and 11 heterosexu als were included in the study. Urogenital and pharyngeal specimens we re tested for C trachomatis and N gonorrhoeae using standard clinical diagnostic procedures. Two different PCR methodologies were also used to detect C trachomatis in the pharyngeal specimens. Results were corr elated with the mode of sexual practice. Results-Oro-genital sexual co ntact was practised by 64.9% (72/111) of heterosexuals in addition to penetrative penovaginal intercourse. Additionally, 62.1% (77/124) of a ll patients did not use any form of barrier protection. Of those who a dmitted to ore-genital sexual contact, 17.6% of patients with a genita l chlamydial infection and 36.4% of those with genital gonorrhoea also had asymptomatic pharyngeal colonisation. C trachomatis was detected in three of 124 (2.4%) pharyngeal specimens by PCR which were reported as negative by chlamydial culture; one was positive by the immune dot blot test. Conclusion-The majority of patients practised unprotected ore-genital contact and significant pharyngeal colonisation by C trach omatis and N gonorrhoeae occurred if genital infection was present. De spite the use of PCR in a population at high risk of sexually transmit ted disease, the prevalence of chlamydia in the pharynx was very low. This indicates that transmission of C trachomatis to the oropharynx do es not pose a serious health risk and that screening of patients for o ropharyngeal C trachomatis is not worthwhile.