Melanie Bissessor

Macrolide resistance and azithromycin failure in a Mycoplasma genitalium-infected cohort, and response of azithromycin failures to alternative antibiotic regimens

BACKGROUND Our aim was to determine the efficacy of 1 g azithromycin and alternative antibiotic regimens in a prospective cohort of Mycoplasma genitalium-infected participants, and factors associated with azithromycin failure. METHODS Consecutive eligible M. genitalium-infected men and women attending the Melbourne Sexual Health Centre between July 2012 and June 2013 were treated with 1 g of azithromycin and retested by polymerase chain reaction (PCR) on days 14 and 28. Cure was defined as PCR negative on day 28. Cases failing azithromycin were treated with moxifloxacin, and those failing moxifloxacin were treated with pristinamycin. Pre- and posttreatment samples were assessed for macrolide resistance mutations (MRMs) by high-resolution melt analysis. Mycoplasma genitalium samples from cases failing moxifloxacin were sequenced for fluoroquinolone resistance mutations. Multivariable analysis was used to examine associations with azithromycin failure. RESULTS Of 155 participants treated with 1 g azithromycin, 95 (61% [95% confidence interval {CI}, 53%-69%]) were cured. Pretreatment MRM was detected in 56 (36% [95% CI, 28%-43%]) participants, and strongly associated with treatment failure (87% [95% CI, 76%-94%]; adjusted odds ratio, 47.0 [95% CI, 17.1-129.0]). All 11 participants who had MRM detected in posttreatment samples failed azithromycin. Moxifloxacin was effective in 53(88% [95% CI, 78%-94%]) of 60 cases failing azithromycin; all failures had gyrA and parC mutations detected in pretreatment samples. Six of 7 patients failing moxifloxacin treatment received pristinamycin, and all were PCR negative 28 days after pristinamycin treatment. CONCLUSIONS We report a high azithromycin failure rate (39%) in an M. genitalium-infected cohort in association with high levels of pretreatment macrolide resistance. Moxifloxacin failure occurred in 12% of patients who received moxifloxacin; all had pretreatment fluoroquinolone mutations detected. Pristinamycin was highly effective in treating macrolide- and quinolone-resistant strains.

Frequent screening for syphilis as part of HIV monitoring increases the detection of early asymptomatic syphilis among HIV-positive homosexual men.

Background:Syphilis continues to be a significant public health problem among HIV-positive men who have sex with men (MSM) internationally. This study aimed to determine whether the routine inclusion of syphilis serology with every blood test performed as part of HIV monitoring increases the detection of early asymptomatic syphilis among HIV-positive MSM. Methods:We examined the effect of this intervention, implemented in January 2007, on the detection of early asymptomatic syphilis among HIV-positive MSM attending the Melbourne Sexual Health Centre, Australia, and compared this with the previous clinic policy of annual syphilis screening. Results:In the 18 months before and after the intervention, the median number of syphilis tests performed per man per year was 1 and 2, respectively. The proportion of MSM diagnosed with early syphilis who were asymptomatic was 21% (3 of 14) and 85% (41 of 48) for the 2 respective periods (P = 0.006). The time between the midpoint since last syphilis serology and diagnosis of syphilis was a median of 107 days (range 9-362) and 45 days (range 23-325) for the 2 periods, respectively (P = 0.018). Conclusions:The inclusion of routine syphilis serology with every blood test performed as part of HIV monitoring in HIV-positive MSM resulted in a large increase in the proportion of men diagnosed with early asymptomatic syphilis. This simple intervention probably also decreased the duration of infectiousness, enhancing syphilis control while also reducing morbidity.

Use of a computer alert increases detection of early, asymptomatic syphilis among higher-risk men who have sex with men.

Our study assessed the impact of a computer alert that reminded clinicians to test men who were at higher risk for syphilis on the rate of syphilis testing and diagnoses. The percentage of high-risk men who have sex with men who were tested for syphilis increased from 77% to 89% (P>.001), and the percentage of such men with asymptomatic syphilis increased from 16% to 53% (P=.001).

Multiplex Assay for Simultaneous Detection of Mycoplasma genitalium and Macrolide Resistance Using PlexZyme and PlexPrime Technology

Mycoplasma genitalium is a cause of non-gonoccocal urethritis (NGU) in men and cervicitis and pelvic inflammatory disease in women. Recent international data also indicated that the first line treatment, 1 gram stat azithromycin therapy, for M. genitalium is becoming less effective, with the corresponding emergence of macrolide resistant strains. Increasing failure rates of azithromycin for M. genitalium has significant implications for the presumptive treatment of NGU and international clinical treatment guidelines. Assays able to predict macrolide resistance along with detection of M. genitalium will be useful to enable appropriate selection of antimicrobials to which the organism is susceptible and facilitate high levels of rapid cure. One such assay recently developed is the MG 23S assay, which employs novel PlexZyme™ and PlexPrime™ technology. It is a multiplex assay for detection of M. genitalium and 5 mutations associated with macrolide resistance. The assay was evaluated in 400 samples from 254 (186 males and 68 females) consecutively infected participants, undergoing tests of cure. Using the MG 23S assay, 83% (331/440) of samples were positive, with 56% of positives carrying a macrolide resistance mutation. Comparison of the MG 23S assay to a reference qPCR method for M. genitalium detection and high resolution melt analysis (HRMA) and sequencing for detection of macrolide resistance mutations, resulted in a sensitivity and specificity for M. genitalium detection and for macrolide resistance of 99.1/98.5% and 97.4/100%, respectively. The MG 23S assay provides a considerable advantage in clinical settings through combined diagnosis and detection of macrolide resistance.

The etiology of infectious proctitis in men who have sex with men differs according to HIV status.

We compared the spectrum of pathogens responsible for infectious proctitis between HIV-positive and HIV-negative men who have sex with men. Only 32% of men with herpes simplex virus (HSV)-associated proctitis had visible external anal ulceration.The etiology of infectious proctitis among HIV-positive and HIV-negative men is as follows: chlamydia (23.4% vs. 21.7%, P = 0.7), gonorrhea (13.4% vs. 10.8%, P = 0.5), HSV-1 (14.2% vs. 6.5%, P = 0.04), HSV-2 (22% vs. 12.3%, P = 0.03), lymphogranuloma venereum (7.8% vs. 0.7%, P = 0.004), and multiple infections (17.7% vs. 8.6%, P = 0.017). Thirty-two percent with HSV proctitis had external anal ulceration.

Delay in the diagnosis of early syphilis among men who have sex with men: need for greater community and health provider education.

The objective of this study was to determine the duration between onset of symptoms of early symptomatic syphilis and diagnosis among men who have sex with men (MSM). A review of cases of primary and secondary syphilis among MSM presented to the Melbourne Sexual Health Centre between January 2003 and August 2007. The mean age of the 123 MSM included was 37 years. Fifty-two percent (n = 64) presented with primary syphilis and 48% (n = 59) with secondary syphilis. Twenty-five percent were HIV-positive. The median rapid plasma reagin titre was 1:32. Of the 34 men referred by general practitioners, referring practitioners did not consider the diagnosis of syphilis in 10 cases of primary syphilis and 20 cases of secondary syphilis. For primary and secondary cases combined, the median duration between onset of symptoms and diagnosis, and onset of symptoms and treatment, was 15 (3–56) and 20 (1–57) days, respectively. The respective durations for secondary syphilis (17 and 23 days) was longer than for primary syphilis (13 and 15 days) (P < 0.05). The mean number of sex partners reported for the prior three months was 8.8 (range 1–15). If early detection and treatment of syphilis is to be optimized in order to improve syphilis control, greater awareness of its symptoms and signs of syphilis need to be promoted among both health-care providers and affected communities.

Increasing Macrolide and Fluoroquinolone Resistance in Mycoplasma genitalium.

Escalating resistance to azithromycin and moxifloxacin is being reported for Mycoplasma genitalium in the Asia-Pacific region. Analyzing 140 infections, we found pretreatment fluoroquinolone-resistance mutations in parC (13.6%) and gyrA (5%). ParC S83 changes were associated with moxifloxacin failure. Combined macrolide/fluoroquinolone-resistance mutations were in 8.6% of specimens, for which recommended therapies would be ineffective.

Increased Detection of Pharyngeal and Rectal Gonorrhea in Men Who Have Sex With Men After Transition From Culture To Nucleic Acid Amplification Testing.

Background This before-and-after study measured the impact of a change in testing methods from culture to nucleic acid amplification testing (NAAT) on the detection of pharyngeal and rectal gonorrhea in men who have sex with men (MSM) on a sexual health service level, including the effect on subgroups anticipated to have higher rates of gonorrhea. Methods In March 2015, Melbourne Sexual Health Centre changed its laboratory method for gonococcal testing from culture to NAAT using the Aptima Combo 2 and Aptima GC tests. We compared the proportion of tests positive for rectal and pharyngeal gonorrhea in MSM using culture in 2014 with those using NAAT in 2015. Results The proportion of tests positive for rectal gonorrhea by NAAT was double that obtained by culture (8% vs 3.9%; prevalence ratio [PR], 2.0; 95% confidence interval [CI], 1.8–2.4) and 5-fold for pharyngeal gonorrhea (8.3% vs 1.6%; PR, 5.2; 95% CI, 4.2–6.4). Similar increases in test positivity were observed in human immunodeficiency virus (HIV)-positive and HIV-negative men. By NAAT, test positivity for rectal gonorrhea was higher in HIV-positive compared with HIV-negative men (15.4% vs 7.3%; PR, 2.1; 95% CI, 1.7–2.6). Culture and NAAT had similar test positivity for rectal gonorrhea among men who reported contact with gonorrhea (24.9% vs 25.3%, PR 1.0, 95% CI 0.8–1.4) and men who presented with symptoms of proctitis (22.2% vs 27.9%, PR 1.3, 95% CI 0.8–2.0). Conclusions A switch from culture to Aptima Combo 2 testing for extragenital gonorrhea in MSM increased detection and was most marked for pharyngeal infections.

The contribution of Mycoplasma genitalium to the aetiology of sexually acquired infectious proctitis in men who have sex with men

This study examined the contribution of Mycoplasma genitalium to sexually acquired infectious proctitis in men who have sex with men (MSM). MSM with symptomatic proctitis between May 2012 and August 2013 were tested for rectal sexually transmitted infections including chlamydia, gonorrhoea, herpes simplex virus (HSV) and M. genitalium. The load of rectal M. genitalium in men with symptomatic proctitis was compared with a separate group of men who had rectal M. genitalium but no symptoms of proctitis. Among 154 MSM with proctitis, rectal M. genitalium was detected in 18 men (12%, 95% CI 6.9-17.1) and was significantly more common among human immunodeficiency virus (HIV) -positive men (21%, 95% CI 9.5-32.6) than HIV-negative men (8%, 95% CI 2.9-13.1; prevalence ratio 3.2, 95% CI 1.2-8.8). Among HIV-positive men the detection of M. genitalium was comparable to that for chlamydia (21%, 95% CI 9.5-32.5), gonorrhoea (25%, 95% CI 16.2-41.8) and HSV (19%, 95% CI 7.9-30.1). Rectal M. genitalium load was significantly higher among the 18 men with symptomatic M. genitalium-associated proctitis than among a separate group of 18 men with asymptomatic rectal M. genitalium infection (60 000 copies of organism/swab versus 10 744 copies of organism/swab, p 0.023). Comprehensive testing for rectal pathogens in MSM with proctitis should include testing for M. genitalium.

Azithromycin 1.5g Over 5 Days Compared to 1g Single Dose in Urethral Mycoplasma genitalium: Impact on Treatment Outcome and Resistance

Background. We evaluated the impact of extended azithromycin (1.5g over 5 days) on selection of macrolide resistance and microbiological cure in men with Mycoplasma genitalium urethritis during 2013–2015 and compared this to cases treated with azithromycin 1g in 2012–2013. Methods. Microbiological cure was determined for men with M. genitalium urethritis treated with azithromycin 1.5g using quantitative polymerase chain reaction specific for M. genitalium DNA on samples 14–100 days post-treatment. Pre- and post-treatment macrolide resistance mutations were detected by sequencing the 23 S gene. Results. There was no difference in proportions with microbiological cure between azithromycin 1.5g and 1g: 62/106 (58%; 95% confidence interval [CI], 49%, 68%) and 56/107 (52%; 95%CI 42–62%), P = .34, respectively. Also, there was no difference in the proportion of wild-type 23 S rRNA (presumed macrolide sensitive) infections cured after 1.5g and azithromycin 1g: 28/34 (82%; 95%CI 65–92%) and 49/60 (82%; 95%CI 70–90%), P=1.0, respectively. There was no difference between 1.5g and 1g in the proportions of wild-type infections with post-treatment resistance mutations: 4/34 (12%; 95%CI 3–27%) and 11/60 (18%; 95%CI 10–30%), respectively, P = .40. Pre-treatment resistance was present in 51/98 (52%; 95%CI 42–62%) cases in 2013–2015 compared to 47/107 (44%; 95%CI 34–54%) in 2012–2013, P = .25. Conclusions. Extended azithromycin 1.5g was no more effective than a single 1g dose at achieving cure of M. genitalium urethritis and importantly did not reduce the selection of macrolide resistance. Nonmacrolide and new approaches for the treatment of M. genitalium urethritis are required.