Mycoplasma genitalium during treatment of male urethritis with josamycin
Abstract
Background
Methods
Microscopy and real-time PCRs were used to diagnose urethritis and non-viral STIs, respectively, in males (n = 320). M. genitalium positive patients were treated with recommended josamycin regimen and treatment efficacy was monitored using quantitative real-time PCR. Macrolide resistance mutations were identified using sequencing of the 23S rRNA gene.
Results
Forty-seven (14.7%) males were positive for M. genitalium only and most (85.1%) of these had symptoms and signs of urethritis. Forty-six (97.9%) males agreed to participate in the treatment efficacy monitoring. All the pre-treatment M. genitalium specimens had wild-type 23S rRNA. The elimination of M. genitalium DNA was substantially faster in patients with lower pre-treatment M. genitalium load, and the total eradication rate was 43/46 (93.5%). Of the six patients with high pre-treatment M. genitalium load, three (50%) remained positive post-treatment and these positive specimens contained macrolide resistance mutations in the 23S rRNA gene, i.e., A2059G (n = 2) and A2062G (n = 1).
Conclusions
M. genitalium was a frequent cause of male urethritis in Moscow, Russia. The pre-treatment M. genitalium load might be an effective predictor of eradication efficacy with macrolides (and possibly additional antimicrobials) and selection of macrolide resistance. Additional in vivo and in vitro data are crucial to support the recommendation of using josamycin as first-line treatment for M. genitalium infections in Russia. It would be valuable to develop international M. genitalium management guidelines, and quantitative diagnostic PCRs determining also M. genitalium load and resistance mutations (for macrolides and ideally also moxifloxacin) should ideally be recommended.
Keywords: Mycoplasma genitalium, Treatment, Treatment efficacy, Treatment failure, Antimicrobial resistance, 23S rRNA, Josamycin, Macrolides, Russia, Male urethritis
Background
Methods
The work was performed at the Department of Molecular Diagnostics and Epidemiology, Central Research Institute for Epidemiology, Moscow, Russia.
Study population
Consecutive males (n = 320) attending one of the venereologist at a sexually transmitted infection (STI) clinic in Moscow, Russia, from December 2006 to January 2008, were enrolled in the study. The males attended the STI clinic due to urethral symptoms or having had unprotected sexual intercourse with new or multiple contact(s). The mean age of the males was 31 years (median age: 30 years; range: 18 to 66 years). All males signed an informed consent form, the males were clinically examined and two urethral swabs were sampled from each patient, i.e. for microscopy and PCR, respectively.
Ethical approval
Ethical approval for the study was obtained by the Central Research Institute for Epidemiology, Moscow, Russia.
Laboratory diagnostics (microscopy and PCR)
Microscopy (1000× magnification) of Gram-stained smears was performed. The presence of ≥5 polymorphonuclear leucocytes (PMNL) per high power field (hpf), in at least 5 hpf, was interpreted as urethritis. For diagnosis, M. genitalium DNA was detected by the real-time PCR assay AmpliSens® M.genitalium-FRT, and the AmpliSens® N.gonorrhoeae-FRT, AmpliSens® C.trachomatis-FRT, and AmpliSens® T.vaginalis-FRT assays (InterLabServices Ltd, Moscow, Russia) were used to diagnose other non-viral STIs. The DNA isolation and PCR assays, which have been previously evaluated, were performed in accordance with the instructions from the manufacturer (InterLabServices Ltd, Moscow, Russia) and as previously described [26-29].
Antimicrobial treatment of patients
In accordance with the Russian treatment guidelines, all M. genitalium positive patients were treated with josamycin 500 mg three times daily, 10 days [21]. Treatment failures with the josamycin regimen were administered moxifloxacin 400 mg daily, 10 days. Patients positive for any other STI (according to the laboratory test results) were also treated in accordance with the Russian treatment guidelines [21].
Monitoring of josamycin treatment efficacy
All M. genitalium positive patients that did not have any other STI, any complicated urogenital infection, or had been administered any antimicrobials in four weeks prior to enrollment, were invited for monitoring of treatment efficacy. In participating patients, one urethral swab (for microscopy) and one first-void urine specimen (for PCR) were sampled, in a standardized and quality assured manner, on treatment onset, 3rd and 8th day of treatment, and 2nd and 14th days after completed treatment. The first-void urine was collected in 50 mL sterile disposable plastic containers, with a calibration scale in mL on the wall of the container. According to instructions and using these containers, the patients collected 15–20 mL of first-void urine (predominantly morning urine and the patients should not had urinated 3 h before). Valid data regarding the time since last micturition was unfortunately not possible to obtain. At each visit, compliance of the therapy was ensured. To quantify the M. genitalium load in these clinical specimens, three in house prepared DNA calibrators based on the gyrB gene (102, 103, 104 genome equivalents (geq)/reaction) were included in the real-time PCR assay AmpliSens® M.genitalium-FRT (InterLabService Ltd, Moscow, Russia) [26]. The M. genitalium concentration detected was expressed as number of geq [log10] per 1 mL of transport media and the M. genitalium load in each specimen was arbitrarily categorized as low (≤4 geq/mL [log10]), moderate (>4 - <6 geq/mL [log10]) or high (≥6 geq/mL [log10]). The M. genitalium positive samples were subsequently preserved at −70°C, that is, prior to sequencing for identification of macrolide resistance mutations.
Identification of macrolide resistance mutations
For identification of macrolide resistance mutations, domain V of the 23S rRNA gene in M. genitalium was sequenced using the previously described primers Mg23S-1992F and Mg23S-2138R [18].
Results
Symptoms/signs, microscopy results and STI etiological agents in all males (n = 320)
Among the 320 males, 222 (69.4%) had symptoms/signs and microscopically confirmed urethritis, and 49 (15.3%) had no symptoms/signs but microscopically verified urethritis (Table 1). Accordingly, in total 271 cases of urethritis were confirmed. C. trachomatis, M. genitalium, Neisseria gonorrhoeae and Trichomonas vaginalis was detected in 102 (37.6%), 46 (17.0%), 29 (10.7%) and 9 (3.3%), respectively, of the 271 urethritis cases. C. trachomatis and M. genitalium was also detected in eight and five, respectively, of the males lacking symptoms/signs and having ≤5 PMNLs/hpf.
Mycoplasma genitalium positive males
In total, M. genitalium was detected in 51 (15.9%) of the 320 includes males. However, four of the M. genitalium positive males were also positive for some additional STI etiological agent, that is, C. trachomatis (n = 2), T. vaginalis (n = 1), and Herpes simplex virus type 2 (n = 1). For the treatment monitoring, these four males were excluded. However, no males were excluded due to having a complicated urogenital infection or taking antimicrobials during the four weeks prior to enrollment. Accordingly, 47 (14.7%) of the 320 males were positive for M. genitalium only, which corresponded to 44 (16.2%) of the confirmed 271 urethritis cases. Of these 47 M. genitalium positive patients, 40 (85.1%) had symptoms of urethritis and ≥5 PMNL/hpf, four (8.5%) were asymptomatic but had ≥5 PMNL/hpf, and three (6.4%) had no symptoms and <5 PMNL/hpf. Twenty-two (46.8%) and 15 (31.9%) of the 47 patients had ≥10 and >50 PMNL/hpf, respectively.
Monitoring of treatment efficacy with josamycin
Forty-six (97.9%) of the 47 males positive for only M. genitalium agreed to participate and attended most of the visits for the monitoring of treatment efficacy with josamycin. The mean age of these participants was 30 years (median age: 30 years; range: 18 to 41 years). The results of the treatment monitoring are summarized in Table 2.
Briefly, 10 (22.2%), 29 (64.4%) and six (13.3%) of the patients had a low (≤4 geq/mL [log10]), moderate (>4 - <6 geq/mL [log10]) and high (≥6 geq/mL [log10]), respectively, pre-treatment M. genitalium load. All the available pre-treatment M. genitalium specimens (n = 45) had a wild-type 23S rRNA gene sequence. After only three days of treatment, 48.9% (22/45) of the examined patients were M. genitalium negative, and after eight days of treatment 88.9% (40/45) were negative. The elimination of M. genitalium DNA was substantially faster in patients with lower pre-treatment M. genitalium load. For example, all the 13 (100%) patients with low pre-treatment bacterial load were M. genitalium negative already after three days of treatment, and only 6.9% (2/29) of patients with moderate pre-treatment M. genitalium load had detectable levels of M. genitalium DNA two days post-treatment, which was eliminated 10–14 days post-treatment. However, of the six patients with high pre-treatment M. genitalium load three (50%) remained positive 10–14 days after completed treatment (Table 2). All these three patients repeatedly assured full compliance to treatment and not having had any sexual contacts between initiation of josamycin therapy and follow up visit 10–14 days after completed treatment. Accordingly, the eradication rate with the josamycin treatment was 43/46 (93.5%). Details regarding the three treatment failures are provided in Table 3.
Treatment failures with josamycin (n = 3)
Briefly, at the time of diagnosis two of the three patients had severe symptoms of urethritis and high number of PMNL/hpf, however, the remaining patient was asymptomatic with <5 PMNL/hpf. In the two symptomatic patients, the symptoms and signs initially resolved. However, one of them had relapsed symptoms and signs of severe urethritis 10–14 days after treatment, which was also the case for the initially asymptomatic patient. The M. genitalium strains in all three patients had mutations in the macrolide resistance region of 23S rRNA during treatment. Accordingly, the M. genitalium strains in two and one of those patients had an A2059G mutation (Escherichia coli numbering) and A2062G mutation, respectively, in the 23S rRNA gene (Table 3). The patients were subsequently successfully treated with moxifloxacin 400 mg daily, 10 days.
Discussion
Conclusions
Acknowledgements
The present work was supported by the Central Research Institute for Epidemiology, Moscow, Russia.
Footnotes
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
AG, MG and MU designed, initiated and coordinated the study. AG, PR, TR, and MG coordinated and performed all the laboratory analyses. AG and MU analysed and interpreted all the data, and wrote a first draft of the paper. All authors read, commented and approved the final manuscript.