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      Mycoplasma genitalium Prevalence, Coinfection, and Macrolide Antibiotic Resistance Frequency in a Multicenter Clinical Study Cohort in the United States

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          Abstract

          The prevalence rates of Mycoplasma genitalium infections and coinfections with other sexually transmitted organisms and the frequency of a macrolide antibiotic resistance phenotype were determined in urogenital specimens collected from female and male subjects enrolled in a multicenter clinical study in the United States. Specimens from 946 subjects seeking care from seven geographically diverse clinical sites were tested for M. genitalium and for Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis. Sequencing was used to assess macrolide antibiotic resistance among M. genitalium-positive subjects. M. genitalium prevalence rates were 16.1% for females and 17.2% for males. Significant risk factors for M. genitalium infections were black race, younger age, non-Hispanic ethnicity, and female symptomatic status. Female M. genitalium infections were significantly more prevalent than C. trachomatis and N. gonorrhoeae infections, while the M. genitalium infection rate in males was significantly higher than the N. gonorrhoeae and T. vaginalis infection rates. The macrolide-resistant phenotype was found in 50.8% of females and 42% of males. These results show a high prevalence of M. genitalium single infections, a lower prevalence of coinfections with other sexually transmitted organisms, and high rates of macrolide antibiotic resistance in a diverse sample of subjects seeking care across a wide geographic area of the United States.

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          Use of TaqMan 5' nuclease real-time PCR for quantitative detection of Mycoplasma genitalium DNA in males with and without urethritis who were attendees at a sexually transmitted disease clinic.

          Mycoplasma genitalium is a cause of nongonococcal urethritis, particularly in patients not infected with Chlamydia trachomatis. A quantitative 5' nuclease assay (TaqMan PCR) was developed and validated. The assay detected a fragment of the MgPa adhesin gene by use of a TaqMan MGB (minor groove binder) probe and included an internal processing control to detect PCR inhibition. Urethral swab specimens and first-void urine samples from M. genitalium-positive men were examined, and the M. genitalium DNA load was correlated to symptoms and signs. The assay consistently detected <5 genome copies without cross-reactions with other mycoplasmas. Urine and urethral swab specimens from men with urethritis had higher M. genitalium DNA loads than specimens from men without urethritis. However, a very broad overlap of DNA loads between patients with and without urethritis was observed. Urethral swab specimens from patients with urethral discharge had a significantly higher DNA load than specimens from patients without discharge. This correlation was not found in first-void urine specimens.
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            Mycoplasma genitalium among young adults in the United States: an emerging sexually transmitted infection.

            We sought to determine the prevalence of and risk factors associated with Mycoplasma genitalium infection in a nationally representative sample of young adults in the United States. Urine specimens from 1714 women and 1218 men who participated in Wave III of the National Longitudinal Study of Adolescent Health (N=14322) were tested for M genitalium. Poststratification sampling weights were used to generate nationally representative estimates. The prevalence of M genitalium was 1.0% compared with 0.4%, 4.2%, and 2.3% for gonococcal, chlamydial, and trichomonal infections, respectively. No M genitalium-positive individuals reported symptoms of discharge. M genitalium prevalence among those who reported vaginal intercourse was 1.1% compared with 0.05% among those who did not. In multivariate analyses, M genitalium prevalence was 11 times higher among respondents who reported living with a sexual partner, 7 times higher among Blacks, and 4 times higher among those who used condoms during their last vaginal intercourse. Prevalence of M genitalium increased by 10% for each additional sexual partner. M genitalium was more prevalent than Neisseria gonorrhoeae but less prevalent than Chlamydia trachomatis, and it was strongly associated with sexual activity.
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              High Prevalence of Antibiotic-Resistant Mycoplasma genitalium in Nongonococcal Urethritis: The Need for Routine Testing and the Inadequacy of Current Treatment Options

              Mycoplasma genitalium and Chlamydia trachomatis are recognized causes of common genital tract morbidities, such as pelvic inflammatory disease and nongonococcal cervicitis in women [1] and nongonococcal urethritis (NGU) in men [2, 3]. UK- and US-based antimicrobial treatment guidelines for these syndromes are aimed at Chlamydia infection, which is more frequently detected and has a strong evidence base for causing chronic disease [4, 5], whereas M. genitalium is not usually recommended among organisms for routine testing in routine sexually transmitted infection screening. NGU, diagnosed using both clinical presentation with Gram-stained urethral smear microscopy, is empirically treated with a 1-week oral course of doxycycline or a single oral dose of 1 g of azithromycin [4, 5]. Both are effective against C. trachomatis, although clinical failure to eradicate Chlamydia with single-dose azithromycin has been reported [6]. For M. genitalium, doxycycline has poor efficacy, evidenced by high rates of clinical failure with tetracyclines [7]; treatment failure with single-dose azithromycin is increasingly evident and associated worldwide with strains possessing single-nucleotide polymorphisms (SNPs) in its ribosomal RNA gene (domain V, 23S rRNA) [8–10]. Moxifloxacin, a fluoroquinolone demonstrating efficacy against M. genitalium, is recommended following treatment failure with macrolides and tetracyclines [1]. Fluoroquinolone resistance–associated SNPs in gyrase (gyrA) or topoisomerase IV (parC) genes have been detected in M. genitalium from patients exhibiting fluoroquinolone treatment failure and phenotypic resistance in vitro [11]. In this study of men symptomatic of urethritis, we investigated the prevalence of M. genitalium in comparison to established causes of urethritis and determined frequencies of known genetic resistance markers to macrolides and fluoroquinolones within M. genitalium. We sought to establish whether prevalence of M. genitalium and resistance was local only to our population or could be applicable more generally, using a previously validated dual-locus typing system. METHODS Patients This was an observational study of all men prospectively presenting with symptoms of urethritis to the Genitourinary Medicine Clinic at St George's Hospital, Tooting, London, between 28 September and 15 December 2011. This study was conducted with the approval of the South West London Research Ethics Committee (number Q0803 71). Patients were designated as having urethritis, NGU, nonchlamydial NGU, or no urethritis. “Urethritis” was defined as any patient receiving treatment specifically for urethritis in that clinical episode and at least 1 of the following: (1) recent history of dysuria, urethral discomfort, or urethral discharge, and visible urethral discharge on examination; (2) ≥5 neutrophils per high-power field on urethral Gram stain. NGU was defined as urethritis where gonorrhea was excluded by at least 2 of Gram stain, nucleic acid amplification test (NAAT), and routine gonococcal culture. Nonchlamydial NGU was defined as NGU where chlamydia had been excluded by NAAT. Only patients consenting to routine urethral smears were included in the study. Patients had a urethral smear prepared with a cotton-tipped swab or plastic loop and were asked to provide a maximum of 50 mL first-catch urine specimen. Clinical notes of patients with urethritis were reviewed at 3 months after presentation to assess instances of treatment failure. Pathogen Detection First-void urine samples were collected routinely for chlamydia and gonorrhea NAATs using the Viper system (Becton Dickinson, Oxford, UK). The residual of these samples were retrieved and used for detection of M. genitalium and T. vaginalis using primers as previously described [12, 13]. DNA extracts positive for M. genitalium were investigated for SNPs in the quinolone resistance–determining regions (QRDRs) of gyrA, gyrB, and parC and macrolide resistance SNPs in 23S rRNA [8] and also typed using a multiple locus variable number tandem repeat marker in MG309 (MG-309-STR) and mgpB SNP analysis [14]. Further details of the protocol are provided in Supplementary Data 1. Statistical Analysis To detect the difference of 25% and 4% of M. genitalium in patients with and without urethritis, respectively [1], with 80% power and α = .05, 111 urethritis and nonurethritis cases each were required. Prevalence of infections was compared between urethritis and no urethritis and also compared within urethritis cases for the same infection, using χ2 and McNemar test, respectively. Sequence Type Assignment and Phylogeny Construction MG191 sequence type (ST) type was assigned on the basis of previously described types [15–17] numbered 1–80. Maximum likelihood phylogeny was reconstructed from ClustalW alignments using RAxML v7.3.2 using a generalized time reversible (GTR) model of nucleotide substitution with gamma model of rate heterogeneity [18]. Branch support values were generated from 1000 bootstrap replicates. RESULTS Prevalence of Infection 217 men were recruited, 18 of whom were men who have sex with men (MSM). One hundred ten of 217 had any urethritis by study definition and 102 of 217 had NGU. The prevalence of C. trachomatis and M. genitalium were similar in NGU cases and both significantly higher than in those with no urethritis (Table 1). The prevalence of both M. genitalium and C. trachomatis among MSM and heterosexual men with NGU was similar (data not shown). The clinic database was checked for all male attendees during the exact period of the study. Of 184 men diagnosed with NGU, 14 were diagnosed with C. trachomatis, giving a prevalence of 7.6% (95% confidence interval [CI], 4.4%–12.7%), lower than in our study. This may have reflected a different threshold for diagnosing NGU in the general clinic compared to our study criteria. Table 1. Prevalence of Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma genitalium, and Trichomonas vaginalis for No Urethritis, Gonococcal Urethritis, Nongonococcal Urethritis (NGU), and Nonchlamydial NGU Organism No Urethritis All Urethritis P Valuea for All Urethritis Nongonococcal Urethritis (NGU) P Valuea for NGU NCNGU P Valuea for NCNGU Neisseria gonorrhoeae 2/107; 1.9% (.0–4.5) 7/109; 6.4% (1.8–11.0) .17 NA … NA … Chlamydia trachomatis 2/107; 1.9% (.0–4.5) 17/109; 15.6% (10.0–24.0) .0001 15/102; 14.7% (7.8–21.6) .0007 NA … Mycoplasma genitalium 5/107; 4.7% (.7–8.7) 17/110; 15.5% (8.7–22.3) .0085 17/102; 16.7% (9.5–24.0) .0047 17/87; 19.5% (11.2–27.8) .0012 Trichomonas vaginalis 0/107 0% 2/110;1.8% (0–4.3) .49 2/102; 2.0% (0–4.7) .24 2/87; 2.3% (0%–5.0%) .46 P value, Ct vs Mgb 1 .86 Data in parentheses represent the 95% confidence intervals. Abbreviations: Ct, Chlamydia trachomatis; Mg, Mycoplasma genitalium; NA, not applicable; NCNGU, nonchlamydial nongonococcal urethritis; NGU, nongonococcal urethritis. a P values represent comparisons with no urethritis. b P values are for comparisons between C. trachomatis and M. genitalium prevalence. Genotypic Resistance Markers Genotypic resistance data were available for both the macrolide and fluoroquinolone antibiotics for all 22 M. genitalium–positive clinical samples (Table 2). Macrolide resistance was detected in 9 samples (41%; [95% CI, 20%–62%]). A single sample, that is, 4.5% (95% CI, 1%–21%), possessed a mutation in the QRDR of parC associated with fluoroquinolone resistance, and this genotype possessed no genotypic resistance markers of macrolide antibiotics. The parC sequence of the isolate containing a SNP within the QRDR and the sequences of domain V of the 23S rRNA gene have been deposited within GenBank under the nucleotide accession numbers HF947096 and HF572928–HF572950, respectively. Table 2. Clinical, Demographic, and Genotypic Characteristics of Patients With Mycoplasma genitalium Infection ID Sexual Orientation Diagnosis Treatment Antibiotics in Last 6 mo Follow-up mgpB SNP Typea MG309 vntr Copy Number 23S rRNA Mutation Mutant Fluoroquinolone QRDR: Amino Acid Changeb Major Cluster mgpB c Major Cluster Dualc 170 MSW NGU Doxycycline ND Nil A 15 A2058G WT A A 202 MSW NGU Doxycycline ND ND 44 Nontypeable A2059C WT A 11 MSW Nil Nil ND 1 wkd 3 9 WT WT A A 227 MSW Nil Nil ND 1 moe 3 11 A2059G WT A A 107 MSW NGU Azithromycin 1 g ND 5 mof E 15 WT parC: S83R (80) A A 141 MSW NGU Azithromycin 1 g ND Nil 4 9 A2058G WT A A 184 MSW Nil Nil ND Nil J 8 A2059G WT A A 183 MSW Nil Nil Ceftriaxone Nil 4 10 A2058G WT A A 219 MSW NGU-HSV Doxycycline ND Nil I 10 WT WT A 189 MSW NGU Doxycycline None Nil H Nontypeable WT WT A 43 MSW NGU Doxycycline ND Nil 3 15 A2058G WT A A 22 MSW NGU Doxycycline Doxycycline 1 mog B 13 WT WT A 174 MSM NGU Doxycycline None Nil G 13 WT WT B B 162 MSW NGU Doxycycline ND Nil C 14 WT WT B B 197 MSW NGU Azithromycin 1 g Azithromycin 1 g Nil 24 10 A2058G WT B B 51 MSW NGU Doxycycline ND 2 moh C 13 WT WT B B 108 MSW NGU Azithromycin 1 g ND Nil 8 9 WT WT B B 111 MSW NGU Doxycycline ND Nil F 9 WT WT B B 218 MSW NGU Doxycycline ND 6 wki 23 19 WT WT B B 88 MSW NGU Azithromycin 1 g ND Nil 21 8 A2059G WT B B 116 MSW Nil Nil ND Nil 2 11 WT WT B B 72 MSW NGU Doxycycline ND Nil D 10 WT WT B B Abbreviations: HSV, herpes simplex virus; MSW, men who have sex with women; ND, not documented; NGU, nongonococcal urethritis; Nil, no follow-up attendance; QRDR, quinolone resistance–determining region; rRNA, ribosomal RNA; SNP, single-nucleotide polymorphism; WT, wild type. a Sources: [8, 14, 15]. b Parentheses represent the codon of Escherichia coli K12. c Both mgpB and dual sequence type phylogenetic analysis produced the same two major clusters as presented in Figure 1. d Persistent symptoms; doxycycline given. e Urethral discharge, nil found. f Chlamydia trachomatis diagnosed–asymptomatic. g Persistent symptoms; azithromycin (2 g) given over 5 days. h Persistent symptoms for 2 months; azithromycin (2 g) over 5 days and metronidazole given. i Persistent symptoms; doxycycline and metronidazole given. There were no obvious clinical associations with antibiotic resistance. Macrolide-associated resistance markers were carried in 6 of 17 and 3 of 5 of those with NGU and no urethritis, respectively. In 1 of these patients, carrying A2058G, the clinical notes indicated reception of single-dose azithromycin for a prior episode of NGU some months previously, raising the possibility of either treatment failure or selection of macrolide resistance from the previous episode. However, none of the 6 cases with NGU and macrolide resistance, 2 of whom were treated with doxycycline and 4 with single-dose azithromycin, returned to the clinic in the following 6 months with episodes of persistent or recurrent urethritis. Relatedness of M. genitalium All 22 M. genitalium DNAs were successfully sequence typed by the MG191 SNP typing system. Eighteen of 22 were successfully typed using MG-309-STR. Table 2 displays MG191 (mgpB) and MG-309-STR types together with 23S rRNA type. Eleven of 22 M. genitalium infections were caused by 8 STs identical to MG191 alleles in the literature [14–16], designated ST 2, 3, 4, 8, 21, 23, 24, and 44. The remaining 11 sequence types exhibited novel MG191 alleles which we have designated as Novel STs A–J (Table 2). Sequences used for typing were deposited in GenBank under accession numbers KC445139 to KC445161 for the mgpB locus and KC445162 to KC445182 for the MG309 locus. Successfully typed MG-309-STR sequences were combined end-to-end with their respective MG191 sequences to form a dual locus sequence type (DLST). Phylogenetic analysis revealed a tree of 18 DLSTs, divided clearly into 2 major clusters, which we designated Major Cluster A (MCA) and B (MCB) (Figure 1). A phylogenetic tree, constructed using only MG191 sequences on study sequence types, produced identical assignments into these major clusters with poorer bootstrap values (data not shown). We therefore assigned the 4 sequence types, in which MG-309-STR had failed, to these major clusters accordingly (Table 2). Seven of 12 MCA types exhibited genotypic resistant mutations (4 A2058G, 2 A2059G, and 1 A2059C), compared with 2 of 10 in MCB (A2058G and A2059G) (Table 2 and Figure 1). We determined the phylogenetic relationship of study M. genitalium STs with 80 other previously typed strains [15–18] from Southern Europe and North Africa, which were typed using MG191-ST alone (Supplementary Figure). The tree suggests that our study M. genitalium STs, including those carrying 23S rRNA mutants, are distributed widely in this group of STs. Figure 1. Phylogenetic tree of 18 of 22 dual locus sequence types of Mycoplasma genitalium detected from symptomatic men attending clinic. The tree was constructed only from samples in which both MgpB and MG309 sequences were available using the mgpB sequence type combined with MG309 vntr sequence (dual locus sequence type). Tips are colored by 23S rRNA single-nucleotide polymorphism type. Branch tips show identity number followed by the abbreviations ST, mgpB sequence type; vntr, MG309 sequence type repeat, and clinical syndrome; NGU, nongonococcal urethritis; Nil, no clinical syndrome. POS indicates positive control. The numbers along the branches represent bootstrap values. Major clusters A and B (see text). DISCUSSION Mycoplasma genitalium was a frequent but undiagnosed cause of NGU, as prevalent as C. trachomatis in our symptomatic, mainly heterosexual male cohort. In addition, >40% of M. genitalium infections had genotypic resistance to macrolide antibiotics, one of the recommended first-line options for NGU. A single patient, approximately 5% of the cohort, was infected with a strain demonstrating genotypic resistance to fluoroquinolones. Patients with M. genitalium infection, with or without genotypic resistance, separated into distinct genotypic clusters and were also related to a diverse population of international control sequence types. This indicated that our findings, rather than being a local clonal phenomenon that could have biased the data, were more likely to represent established infection and resistance rates in this patient population as a whole. This also complements evidence that selection of macrolide-resistant M. genitalium during suboptimal treatment [19] contributes to cases of treatment failure rather than ongoing horizontal transmission of resistant bacterial strains. Overall, our findings indicate that there is a need to provide routine testing for M. genitalium in those presenting with symptoms of urethritis and perhaps cervicitis and that first-line recommended antimicrobial options for treating these syndromes need reappraisal [20, 21]. These treatment options will need to take into account the need to have effective regimens against both C. trachomatis and M. genitalium and should question the value of recommending either doxycycline or single-dose azithromycin alone. Whereas extended-dose azithromycin for NGU may be more effective in preventing the development of macrolide resistance and treatment failure, the in vitro and clinical data suggest that it will not work for those carrying 23s rRNA resistance-associated SNPs [19]. Future effective NGU regimens are likely to include fluoroquinolones. Solitary parC mutations, like the one documented in this study, have been reported in cases of fluoroquinolone treatment failure of M. genitalium [22, 23], and worryingly, there already exist reports of moxifloxacin treatment failure in M. genitalium–associated persistent NGU [24]. Collectively, these findings point to the need to evaluate effectiveness of new treatment strategies, including combination therapies and novel antimicrobials. Effective management can be further guided by providing routine testing for M. genitalium infection [25], and tests of cure following therapy. The prospect of rapid and accurate tests for infections that include validated genetic markers of resistance [26, 27] will allow for appropriately targeted treatment and reduce need for complex regimens. Current rapid test platforms in development, including those recently approved for C. trachomatis and Neisseria gonorrhoeae, offer potential for such resistance tests to be realized [28]. The prevalence of M. genitalium in NGU in our study was perhaps at the lower end of the range of that described in previous work of 15%–25% [3]. Recent reports in South Africa mirror our findings of higher rates of M. genitalium infection relative to C. trachomatis [29], and importantly, comparable rates of macrolide resistance and emerging evidence of resistance to resistance to fluoroquinolones were reported in Sydney, Australia [30], suggesting that the problem may be globally widespread. Although this study is limited by being based in a single clinic as well as conducted over a relatively short period of time, we addressed this by assessing the genetic diversity of M. genitalium within our cohort, utilizing a typing system with the discriminatory power to be useful in the study of sexual networks [14]. This robustly revealed 2 major clusters of M. genitalium, both of which contained drug-resistant mutations. Each cluster itself contained different MG191 STs, many of which had been previously identified. The MG191 typing system alone is less discriminatory and more useful to describe broad epidemiological STs [14]. Using this system, we showed that most STs within each cluster were not closely related as they were distributed broadly among international genotypes also typed using MG191. In conclusion, the prevalence of macrolide-resistant M. genitalium in this population is much higher than previously thought and M. genitalium is detected as frequently as C. trachomatis in cases of NGU. Current testing and treatment guidelines should be modified to incorporate these findings. Supplementary Data Supplementary materials are available at Clinical Infectious Diseases online (http://cid.oxfordjournals.org). Supplementary materials consist of data provided by the author that are published to benefit the reader. The posted materials are not copyedited. The contents of all supplementary data are the sole responsibility of the authors. Questions or messages regarding errors should be addressed to the author. Supplementary Data
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                Author and article information

                Contributors
                Role: Editor
                Journal
                J Clin Microbiol
                J. Clin. Microbiol
                jcm
                jcm
                JCM
                Journal of Clinical Microbiology
                American Society for Microbiology (1752 N St., N.W., Washington, DC )
                0095-1137
                1098-660X
                15 June 2016
                24 August 2016
                September 2016
                24 August 2016
                : 54
                : 9
                : 2278-2283
                Affiliations
                [a ]Hologic, Inc., San Diego, California, USA
                [b ]Occidental College, Los Angeles, California, USA
                Mayo Clinic
                Author notes
                Address correspondence to Damon Getman, damon.getman@ 123456hologic.com .
                [*]

                Present address: Seth Cohen, Mercy San Juan Medical Center, Carmichael, California, USA.

                Citation Getman D, Jiang A, O'Donnell M, Cohen S. 2016. Mycoplasma genitalium prevalence, coinfection, and macrolide antibiotic resistance frequency in a multicenter clinical study cohort in the United States. J Clin Microbiol 54:2278–2283. doi: 10.1128/JCM.01053-16.

                Article
                01053-16
                10.1128/JCM.01053-16
                5005488
                27307460
                2131c67b-f80c-4112-b955-410ad8587769
                Copyright © 2016 Getman et al.

                This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.

                History
                : 16 May 2016
                : 3 June 2016
                : 9 June 2016
                Page count
                Figures: 1, Tables: 3, Equations: 0, References: 38, Pages: 6, Words: 5654
                Funding
                This study was funded by Hologic, Inc.
                Categories
                Epidemiology

                Microbiology & Virology
                Microbiology & Virology

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