Extensive Horizontal Gene Transfer in Ureaplasmas from Humans Questions the Utility of Serotyping for Diagnostic Purposes

Abstract

Ureaplasma parvum and Ureaplasma urealyticum are sexually transmitted, opportunistic pathogens of the human urogenital tract. There are 14 known serovars distributed between the two species. For decades, it has been postulated based upon limited data that virulence is related to serotype specificity. The results were often inconclusive due to the small sample size and extensive cross-reactivity between certain serovars. We developed real-time quantitative PCRs that allow reliable differentiation of the two species and type strains of each of the 14 serovars. To investigate species and serovar distributions, we typed 1,061 clinical isolates of human ureaplasmas from diverse patient populations. There was only a tenuous association between individual Ureaplasma serovars and certain patient populations. This may in part be explained by the fact that almost 40% of the isolates were genetic mosaics, apparently arising from the recombination of multiple serovars. This explains the extensive cross-reactivity based upon serotyping and the lack of consistent association of given serotypes with disease.

High-Resolution Melt PCR Analysis for Genotyping of Ureaplasma parvum Isolates Directly from Clinical Samples

“…Similarly, in a study that examined 1,061 U. parvum/U. urealyticum isolates from a range of sample/disease types, Xiao et al (13) found that SV3 was the most common of all U. parvum serovars (65%) but could not define any consistent pattern between specific serovars and disease groups. In contrast, in a study of endo- cervical, urethral, and vaginal swabs, De Francesco et al (27) reported that SV1 and the combination of SV3 and SV14 (not separated beyond this description) were the most frequent isolates (37% and 39%, respectively), followed by SV6 (24%).…”

“…It is still very important to identify the presence of U. urealyticum, which may be of high clinical relevance to certain conditions, such as pelvic inflammatory disease/endometritis, nongonococcal urethritis, and BPD (13). As such, the HRM assay described here is designed to complement assays that initially detect U. parvum and U. urealyticum, as we have utilized it in this study with the urease gene assay described by Yi et al (20).…”

“…reported (1,13,27,28). Since the inception of molecular assays that have allowed the genotyping of U. parvum, a small number of studies have described serovar distribution within different clinical samples.…”

Identification and Subtyping of Clinically Relevant Human and Ruminant Mycoplasmas by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

“…This taxon was split 10 years ago into two distinct species, U. parvum and U. urealyticum, corresponding to the former biovar 1 (including 4 serovars) and biovar 2 (including 10 serovars), respectively (37). The distinction between the species requires either antibody-based phenotyping methods, which are often inconclusive because of multiple cross-reactions, or more accurate molecular techniques (14,38). Although an additional overnight incubation was necessary to obtain a 100-ml culture volume, MALDI-TOF MS allowed for easy identification of Ureaplasma spp.…”

Molecular biology of mycoplasmas: from the minimum cell concept to the artificial cell

“…One of the fi rst studies to demonstrate horizontal gene transfer was between different serotypes of Ureaplasma sp., isolated from clinical samples (Xiao et al 2011 2007). Nevertheless, half of these genes' functions are still unknown, and the mass transfer of genes is not believed to have had a very signifi cant role in the evolution of mollicutes.…”