Single-Locus-Sequence-Based Typing of the mgpB Gene Reveals Transmission Dynamics in Mycoplasma genitalium

Abstract

Sexually transmitted infections (STIs) by Mycoplasma genitalium are a major problem worldwide, especially given their marked and rapid propensity for developing antimicrobial resistance. Since very few treatment options exist, clinicians face an important challenge in the management of the infection. In this scenario, little is known regarding the transmission dynamics of M. genitalium and the epidemiology of antimicrobial resistance. This mgpB-based molecular typing study, conducted among 54 asymptomatically infected individuals prospectively recruited from an STI screening service, reveals two distinct epidemiological clusters that significantly correlate with sexual conduct in heterosexuals and men who have sex with men (MSM), respectively. This well-defined structuration suggests the presence of two independent sexual networks with little connectivity between them. On the other hand, the study demonstrates the multiclonal feature of the emergence of antibiotic resistance in M. genitalium to both macrolides and fluoroquinolones. The high prevalence of macrolide resistance in M. genitalium among MSM, influenced by dense network connectivity and strong antibiotic selective pressure, may correspond to allodemics affecting other STIs such as gonorrhea, syphilis and enteric pathogens. Collaterally, the structural and functional impact of mutations in the mgpB gene, encoding the major adhesin P140 (MgpB), may require further investigation.

Keywords: Mycoplasma genitalium; antimicrobial resistance; molecular typing; transmission dynamics.

FIG 1

Clustering dendrogram using the mgpB-based single-locus-sequence-based typing from M. genitalium strains of asymptomatically infected individuals. The sequence of the M. genitalium G37 strain is used as a reference (accession number NC_000908.2). Macrolide resistance-associated mutations in the 23S rRNA gene and fluoroquinolone resistance-associated mutations in the parC gene are also shown (M. genitalium numbering). The last column (w) accounts for the study week of specimen collection. The red dashed lines constitute clusters mostly represented by MSM. Bootstrapping values are presented in Fig. S2. Abbreviations: MSM, men who have sex with men; MSMBI, bisexual men; MSW, men who have sex with women; HIV, human immunodeficiency virus; ND, not determined (i.e., infection reported as macrolide resistant by the ResistancePlus MG kit, but not confirmed with sequencing); MXD, mixed genotypes (i.e., MGSP_129 presented genotypes A2072G and wild type, while both MGSP_173 and MGSP_171 strains harbored genotypes A2072G, A2071G, and wild type in the 23S rRNA gene).