Oropharyngeal Chlamydia in MSM attending STI clinic of India

Dear Editor,

Men having sex with men (MSM) are at high risk for sexually transmitted infections (STIs) including oropharyngeal STIs. Extragenital Chlamydia infection is usually asymptomatic and can be missed if not screened for. This study aimed to determine the rate of infection of oropharyngeal Chlamydia trachomatis (CT) among MSM.

All consecutive MSM presenting to the STI Clinic of our hospital between April 2021 and November 2022 were included in the study. Oropharyngeal swabs along with first-void urine and rectal swabs were collected from each patient. Polymerase chain reaction targeting the cryptic plasmid was performed to detect CT. Genotyping was performed by determining the sequences of the ompA gene.¹ In addition, Ureaplasma spp., M. hominis and N. gonorrhoeae were tested by PCR as described previously.^2,3

A total of 128 patients (mean age 30.1 years ± standard deviation 8.8) were included in the study. Of these, 37.5% (48/128) were seropositive for HIV-1 and 32.8% (42/128) were VDRL reactive. At the pharyngeal site, CT was detected in nine (7%), N. gonorrhoeae in two (1.6%), Ureaplasma spp. in one patient (0.8%). No patient tested positive for M. hominis. Among the patients who tested postive for CT at the pharyngeal site, two were seropositive for HIV-1 and none were VDRL reactive. All these patients were asymptomatic at the pharyngeal site and had concomitant infections at other sites also. CT was detected at all three sites (pharyngeal, rectal, and urethral) in four patients, while the five patients had a concomitant rectal infection. Genotyping was performed for all these isolates [Table 1]. Genotype D was the most common genotype at all sites.

In a review by Chan et al, the prevalence of pharyngeal Chlamydia and Gonorrhea among MSM ranged from 0 to 3.6% (median 1.7%) and 0.5–16.5% (median 4.6%) respectively.⁴ In our study, detection of pharyngeal CT was relatively higher. Condomless sexual practices including oral sexual activities can lead to the transmission of STIs. None of the pharyngeal CT positive patients in our study reported condom usage and all had multiple partners.

Similar to our results, Zhou et. al. reported genotype D as the most common genotype at the anorectal site in MSM while genotypes G and D at the urethral and pharyngeal site.⁵ In our study, out of the nine oropharyngeal CT isolates, only four could be successfully genotyped. ompA being a single-copy gene can result in lower sensitivity of genotyping, as also suggested by Hinkan et al.⁶ In two patients, genotype D was present at both pharyngeal and rectal sites. In another two patients, genotype D was present at rectal sites, whereas genotype G and E were recovered from pharyngeal site. History of multiple partners can explain the presence of different genotypes at different anatomical sites in these patients.

The small number of CT positive patients could not allow any statistical inference to be made which is a limitation of our study. Additionally, we were unable to find other studies from India on genotypes of oropharyngeal CT infection in MSM. The results of this study adds to the limited literature available on oropharyngeal CT infection. Our study provides evidence necessitating further research to explore extragenital CT screening in MSM, especially at the pharyngeal site, which can aid in the formulation of screening and testing recommendations and guidelines.