Mycoplasma genitalium prevalence, bacterial load, and antibiotic resistance in paired vaginal and anal specimens from Chlamydia trachomatis-infected women.

BACKGROUND

Mycoplasma genitalium (MG) frequently co-infects women with Chlamydia trachomatis (CT), but the epidemiology and clinical significance of this association remain poorly understood. This study assessed MG positivity, antimicrobial resistance, mgpB genotyping and bacterial load in paired self-collected vaginal and anal swabs from 426 women with urogenital CT infection, and assessed the risk factors for CT/MG coinfection compared with CT monoinfection.

METHODS

MG detection and quantification were carried out using an in-house quantitative PCR targeting the MgPa adhesin gene. Macrolide and fluoroquinolone resistance-associated mutations were determined by sequencing the 23S RNA gene and the parC gene, respectively. The mgpB types were determined by sequencing a 281-bp region of the mgpB gene. Clinical, demographic, and behavioural characteristics were compared between women with CT monoinfection and CT/MG coinfection.

RESULTS

MG was detected in 22.8% of women, more frequently in vaginal than anal specimens (18.5% vs 12.9%, p = 0.03). Among MG-positive women, 43.3% had vaginal-only infection, 18.6% anal-only infection, and 38.1% infection at both sites. Macrolide and fluoroquinolone resistance were detected in 16.7% and 9.1% of evaluable cases, respectively. Anal MG was usually asymptomatic and unrelated to reported anal intercourse. MG bacterial load was significantly higher in vaginal than anal samples, and paired specimens shared identical mgpB genotypes, supporting the hypothesis of secondary anal colonization from the vagina. Being born in France was the only factor associated with CT/MG coinfection, compared with CT monoinfection in the multivariate analysis. MG coinfection did not influence the CT bacterial load.

CONCLUSIONS

MG coinfection was common among women with CT infection but was not associated with higher CT bacterial load, more severe clinical manifestations, or distinct behavioural characteristics. Further studies are warranted to clarify the biological interactions between these two pathogens in women.