Phylogenetics of Mycoplasma hominis clinical strains associated with gynecological infections or infertility as disclosed by an expanded multilocus sequence typing scheme

Abstract

To our knowledge, the phylodistribution of M. hominis clinical strains associated with various pathological conditions of the urogenital tract has not been explored hitherto. Here we analyzed the genetic diversity and phylogenetic relationships among 59 M. hominis Tunisian clinical isolates, categorized as gynecological infections- or infertility-associated pathotypes. For this purpose, we developed an expanded multilocus sequence typing (eMLST) scheme, combining the previously reported multilocus sequence typing (MLST) loci (gyrB, tuf, ftsY, uvrA, gap) with a new selected set of putative virulence genes (p120’, vaa, lmp1, lmp3, p60), referred herein to as multi-virulence-locus sequence typing (MVLST) loci. In doing so, M. hominis population was segregated into two distinct genetic lineages, which were differentially associated with each pathotype. Such a clear dichotomy was supported by several phylogenetic and population genetic analysis tools. Recombination was found to take place, but not sufficient enough to break down the overall clonal population structure of M. hominis, most likely as a result of purifying selection, which accommodated the most fit clones. In sum, and owing to the eMLST scheme described herein, we provide insightful data on the phylogenetics of M. hominis, arguing for the existence of genetically differentiable urogenital pathotypes.

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“…3 In comparison with Ureaplasma spp. and Mycoplasma pneumoniae, Mycoplasma hominis displays high levels of genetic and antigenic heterogeneity among clinical isolates as disclosed by several molecular typing methods, 2,4 which lends further support to the virulence of this species.…”

“…From the 65 isolates, 59 were previously characterized using an Expanded MultiLocus Sequence Typing (eMLST) scheme, including ten genes (uvrA, gyrB, ftsY, tuf, gap, p120ʹ, vaa, lmp1, lmp3, p60). 2 The remaining six isolates were genetically typed in this study by the same method. The sequences generated by eMLST were submitted to the Mycoplasma hominis MLST website (https:// pubmlst.org/mhominis/) sited at the University of Oxford.…”

“…12 Amplicons were then sequenced. 2 Sequences were analyzed using BioEdit and translated into amino acids. Amino acid substitutions in L4 and L22, as well as nucleotide mutations in domain II and domain V of 23S rRNA, were identified by comparison with the corresponding sequences of Escherichia coli ER1709 (GenBank accession number: CP030240.1).…”

“…1 Ample evidence from recent studies conducted in Tunisia indicates that M. hominis is one of the potential causative agents that play an important role in the pathogenesis of human infertility with a prevalence of 83%. 2 And only 17% were associated with gynecological infections. 2 However, M. hominis is less frequent among women suffering from complications during pregnancy (2,5%), in Tunisia.…”

“…2 And only 17% were associated with gynecological infections. 2 However, M. hominis is less frequent among women suffering from complications during pregnancy (2,5%), in Tunisia. 3 In comparison with Ureaplasma spp.…”