Molecular Characterization and Detection of Macrolide and Fluoroquinolone Resistance Determinants in Mycoplasma genitalium in South Africa, 2015 to 2018.

BACKGROUND

Antimicrobial resistance in Mycoplasma genitalium is a global concern, as therapeutic options are limited. We aimed to determine the prevalence of macrolide and fluoroquinolone resistance-associated genetic determinants and strain diversity in M. genitalium-positive surveillance specimens from symptomatic primary health care center attendees in South Africa (2015-2018). A secondary objective was to investigate for an association between M. genitalium strain type, HIV serostatus, and antimicrobial resistance.

METHODS

A total of 196 M. genitalium-positive specimens from adult males and females presenting with genital discharge to primary health care centers were tested for resistance-associated mutations in 23S rRNA, parC and gyrA. A dual-locus sequence type (DLST) was assigned to M. genitalium strains based on the detection of single nucleotide polymorphisms in the semiconserved 5' region of the mgpB gene (MG191-sequence typing) as well as the enumeration of short tandem repeats within the lipoprotein gene (MG309 short tandem repeat typing).

RESULTS

The A2059G mutation in 23S rRNA, associated with macrolide resistance, was detected in 3 of 182 specimens (1.7%; 95% confidence interval, 0.3-4.7). We did not detect gyrA or parC mutations associated with fluoroquinolone resistance in specimens that could be sequenced. Molecular typing with DLST revealed genetic heterogeneity, with DLST 4-11 being the most common M. genitalium strain type detected. There were no associations between DLST and macrolide resistance or HIV infection.

CONCLUSIONS

We found a low prevalence of M. genitalium strains with macrolide resistance-associated mutations over a 4-year surveillance period. Ongoing antimicrobial resistance surveillance is essential for informing genital discharge syndromic treatment guidelines.