Detection of parC gene mutations associated with quinolone resistance in Mycoplasma genitalium: evaluation of a multiplex real-time PCR assay.

Introduction. Increasing levels of antibiotic resistance are complicating treatment for the sexually transmitted pathogen Mycoplasma genitalium. Resistance to fluoroquinolones is associated with mutations in the parC gene. Although the precise mutations conferring resistance are not fully understood, the single nucleotide polymorphism (SNP) G248T/S83I is most implicated.Aim. To evaluate the performance of the MG+parC(beta2) assay (SpeeDx, Australia), which detects single nucleotide polymorphisms (SNPs) in the parC gene at amino acid position S83 (A247C/S83R, G248T/S83I, G248A/S83N) and D87 (G259A/D87N, G259T/D87Y, G259C/D87H).Methods. Clinical samples were analysed by MG+parC(beta2) assay and results compared to Sanger sequencing. Sensitivity, specificity, and predictive value for treatment failure were calculated.Results. From analysis of 205 samples, the MG+parC(beta2) assay performed with a high sensitivity 98.2% (95% CI:90.3-100) and specificity 99.3% (95% CI:96.3-100) for parC SNP detection with a kappa of 0.97 (95% CI:0.94-1.00). The predictive value of G248T/S83I detection (the most common SNP, prevalence of 13% in the study population) was analysed with respect to treatment failure (patients received sequential doxycycline-moxifloxacin). The positive-predictive-value for moxifloxacin failure after detection of S83I was only 44% (95% CI:24.4-65.1), while negative-predictive-value was high at 96.9% (95% CI:92.7-99.0), suggesting that other SNPs are contributing to resistance.Conclusion. MG+parC(beta2) performed with high concordance compared to Sanger sequencing. Such qPCR assays can assist in understanding causes of treatment failure, inform the development of diagnostic assays, and can be applied to surveillance of mutations in populations. Due to an incomplete understanding of the basis for fluoroquinolone resistance, such tests do not appear to be ready for clinical application.

Multicenter Clinical Evaluation of a Novel Multiplex Real-Time PCR (qPCR) Assay for Detection of Fluoroquinolone Resistance in Mycoplasma genitalium.

Mycoplasma genitalium causes a common sexually transmitted infection with a marked propensity to develop antimicrobial resistance. As few treatment options exist, this poses significant challenges to clinicians. Recent diagnostic advances have resulted in tests that report the simultaneous detection of M. genitalium and any resistance to macrolides, the first-line treatment. This allows for therapy to be tailored to the individual, thereby optimizing treatment outcomes. However, resistance to fluoroquinolones, the second-line treatment, is increasing in M. genitalium In this study, we describe a new assay, MG+parC (beta), which simultaneously reports the detection of M. genitalium and five parC mutations that have been associated with resistance to fluoroquinolones. These mutations affect the amino acid sequence of ParC at residues S83R (A247C), S83I (G248T), D87N (G259A), D87Y (G259T), and D87H (G259C). The study tested the MG+parC (beta) assay with 202 M. genitalium-positive clinical samples from Australia (n = 141) and Spain (n = 61). Compared to Sanger sequencing, the assay performed with a kappa value of 0.985 (95% confidence interval [CI], 0.955 to 1.000), with a mutation detection sensitivity of 97.6% (95% CI, 87.4 to 99.9), and specificity of 100.0% (95% CI, 97.7 to 100.0). Fluoroquinolone resistance-associated mutations in parC targeted by the assay were more prevalent among the Australian cohort (23.4% [95% CI,16.3 to 31.8]) compared to the Spanish population (8.8% [95% CI, 2.9% to 19.3%]) (P = 0.019). The MG+parC (beta) kit is a simple and reliable method for simultaneous detection of M. genitalium and fluoroquinolone resistance-associated mutations in clinical settings. This novel diagnostic tool may extend the utility of the second line of antimicrobial therapies in M. genitalium infection.

Intravenous esomeprazole (40 mg and 20 mg) inhibits gastric acid secretion as effectively as oral esomeprazole: results of two randomized clinical studies.

OBJECTIVES: Two studies compared the effects of intravenous (i.v.) and oral esomeprazole (40 mg and 20 mg) on gastric acid suppression and pharmacokinetics after both single (day 1) and repeated (day 5) dosing. METHODS: Two randomized, two-way, cross-over, comparative studies of similar design were performed in healthy male and female volunteers. In both studies, subjects received esomeprazole as a 30-min i.v. infusion or orally once-daily for 5 days, separated by a wash-out period of at least 13 days. In one study, which was double-blind (double dummy), subjects received 40 mg esomeprazole. In the other open study, subjects were given 20 mg esomeprazole. RESULTS: In total, 40 and 24 subjects were randomized for treatment with 40 mg and 20 mg esomeprazole, respectively. No significant differences were found between i.v or oral administration of esomeprazole with respect to the amount of time with mean intragastric pH>4 throughout day 1 or day 5 of treatment in the 40 mg study (day 1, 10.1 h and 8.8 h versus day 5, 15.9 h and 15.3 h, respectively) and the 20 mg study (day 1, 7.3 h and 6.6 h versus day 5, 11.9 h and 12.3 h, respectively). The area under the plasma concentration-time curve values were higher following i.v. relative to oral administration on day 1 of dosing, with less pronounced differences after repeated (day 5) dosing. Both administration routes were similarly well tolerated. CONCLUSIONS: Esomeprazole, 40 mg and 20 mg i.v., provides similar levels of intragastric acid control on both day 1 and day 5 of treatment compared with oral administration.