Concurrent titration and determination of antibiotic resistance in ureaplasma species with identification of novel point mutations in genes associated with resistance

Ureaplasma infections: update on epidemiology, antimicrobial resistance, and pathogenesis

Human Ureaplasma species are being increasingly recognized as opportunistic pathogens in human genitourinary tract infections, infertility, adverse pregnancy, neonatal morbidities, and other adult invasive infections. Although some general reviews have focused on the detection and clinical manifestations of Ureaplasma spp., the molecular epidemiology, antimicrobial resistance, and pathogenesis of Ureaplasma spp. have not been adequately explained. The purpose of this review is to offer valuable insights into the current understanding and future research perspectives of the molecular epidemiology, antimicrobial resistance, and pathogenesis of human Ureaplasma infections. This review summarizes the conventional culture and detection methods and the latest molecular identification technologies for Ureaplasma spp. We also reviewed the global prevalence and mechanisms of antibiotic resistance for Ureaplasma spp. Aside from regular antibiotics, novel antibiotics with outstanding in vitro antimicrobial activity against Ureaplasma spp. are described. Furthermore, we discussed the pathogenic mechanisms of Ureaplasma spp., including adhesion, proinflammatory effects, cytotoxicity, and immune escape effects, from the perspectives of pathology, related molecules, and genetics.

Antimicrobial susceptibilities and mechanisms of resistance of commensal and invasive Mycoplasma salivarium isolates

Mycoplasma salivarium, an oral commensal organism, can cause severe invasive infections in immunocompromised individuals. Currently there is no treatment guidance for such infections. We performed antimicrobial susceptibility tests on 39 commensal and invasive M. salivarium isolates and investigated the mechanisms of antimicrobial resistance. Clindamycin was the most active agent [minimum inhibition concentration (MIC) range: 0.004–128 mg/L, MIC₅₀ = 0.031 mg/L, MIC₉₀ = 0.125 mg/ml], followed by tetracycline and levofloxacin. All isolates were resistant to erythromycin (MIC ≥4 mg/L) due to the presence of 2057A (Escherichia coli numbering) in 23S rRNA. Three isolates with elevated clindamycin MICs (≥8 mg/L) harbored A2058T/G mutations in 23S rRNA gene; four sequential isolates from one patient developed C2611T and A2059G mutations accompanying the increase of clindamycin MICs. Five isolates with elevated tetracycline MICs (≥4 mg/L) had mutations in 16S rRNA gene (A965G/T, G966T, or A967C/T) and one of them harbored TetM. Nine isolates with elevated levofloxacin MICs (≥4 mg/L) had one or more mutations in gyrA, gyrB, parC, or parE. Susceptibility breakpoints for clindamycin, tetracycline and levofloxacin were suggested to be ≤0.125, ≤2, and ≤2 mg/L, respectively. Antimicrobial resistance to any of the three agents (clindamycin, tetracycline, or levofloxacin) was documented in 12 (34.3%) non-duplicate isolates, of which 10 were invasive. Levofloxacin resistance was most frequent (25.7%). Multi-drug resistance was also observed (14.3%). This study demonstrates the frequent occurrence of antimicrobial resistance in M. salivarium, emphasizing the need for culture and susceptibility testing to guide antimicrobial therapy.

Antibiotic resistance among clinical Ureaplasma isolates from Cuban individuals between 2013 and 2018

Introduction. Acquired resistance against the antibiotics that are active against Ureaplasma species has been described.Hypothesis/Gap Statement. Diagnostics combined with antimicrobial sensitivity testing are required for therapeutic guidance.Aim. To report the prevalence of antimicrobial resistance among Cuban Ureaplasma isolates and the related molecular mechanisms of resistance.Methodology. Traditional broth microdilution assays were used for antimicrobial sensitivity testing in 262 clinical Ureaplasma species isolates from Cuban patients between 2013 and 2018, and a subset of samples were investigated in parallel with the commercial MYCO WELL D-ONE rapid culture diagnostic assay. The underlying molecular mechanisms for resistance were determined by PCR and sequencing for all resistant isolates.Results. Among the tested isolates, the tetracycline and erythromycin resistance rates were 1.9 and 1.5%, respectively, while fluoroquinolone resistance was not found. The tet(M) gene was found in all tetracycline-resistant isolates, but also in two tetracycline-susceptible Ureaplasma clinical isolates. We were unable to determine the underlying mechanism of erythromycin resistance. The MYCO WELL D-ONE kit overestimated tetracycline and erythromycin resistance in Ureaplasma spp. isolates.Conclusions. Although low levels of antibiotic resistance were detected in Cuban patients over a 5-year period, continued surveillance of the antibiotic susceptibility of Ureaplasma is necessary to monitor possible changes in resistance patterns.

Oxa-376 and Oxa-530 variants of β-lactamase: computational study uncovers potential therapeutic targets of Acinetobacter baumannii

Antimicrobial resistance is a major global health crisis, resulting in thousands of deaths each year. Antibiotics' effectiveness against microorganisms deteriorates over time as multidrug resistance (MDR) develops, which is exacerbated by irregular antibiotic use, poor disease management, and the evasive nature of bacteria. The World Health Organization has recognized multidrug resistance as a critical public health concern, and Acinetobacter baumannii has been at the center of attention due to its ability to develop multidrug resistance (MDR). It generally produces carbapenem-hydrolyzing oxacillinase, which has been identified as the primary source of beta-lactam resistance in MDR bacteria. Recently, point mutations in A. baumannii have been identified as a key factor of multidrug resistance, making them a prime concern for researchers. The goal of the current work was to establish a unique way of finding multidrug-resistant variants and identify the most damaging mutations in the existing databases. We characterized the deleterious variants of oxacillinases using several computational tools. Following a thorough analysis, Oxa-376 and Oxa-530 were found to be more damaging when compared with the wild-type Oxa-51. The mutants' 3D structures were then prepared and refined with RaptorX, GalaxyRefine, and SAVES servers. Our research incorporates seven antimicrobial agents to illustrate the resistance capability of the variants of oxacillinase by evaluating binding affinity in Autodock-vina and Schrodinger software. RMSD, RMSF, Radius of gyration analysis, the solvent-accessible surface area (SASA), hydrogen bonding analysis and MM-GBSA from Molecular Dynamics Simulation revealed the dynamic nature and stability of wild-type and Oxa-376 and Oxa-530 variants. Our findings will benefit researchers looking for the deleterious mutations of Acinetobacter baumannii and new therapeutics to combat those variants. However, further studies are necessary to evaluate the mechanism of hydrolyzing activity and antibiotic resistance of these variants.

Determining novel therapeutic targets of Acinetobacter baumannii. Deleterious variants, causing antibiotic resistance, were identified by molecular docking and molecular dynamics simulation suggesting new therapeutic targets Oxa-376 and Oxa-530.

Defining Fluoroquinolone Resistance-Mediating Mutations from Non-Resistance Polymorphisms in Mycoplasma hominis Topoisomerases

Often dismissed as a commensal, Mycoplasma hominis is an increasingly prominent target of research due to its role in septic arthritis and organ transplant failure in immunosuppressed patients, particularly lung transplantation. As a mollicute, its highly reductive genome and structure render it refractile to most forms of treatment and growing levels of resistance to the few sources of treatment left, such as fluoroquinolones. We examined antimicrobial susceptibility (AST) to fluoroquinolones on 72 isolates and observed resistance in three (4.1%), with corresponding mutations in the quinolone resistance-determining region (QRDR) of S83L or E87G in gyrA and S81I or E85V in parC. However, there were high levels of polymorphism identified between all isolates outside of the QRDR, indicating caution for a genomics-led approach for resistance screening, particularly as we observed a further two quinolone-susceptible isolates solely containing gyrA mutation S83L. However, both isolates spontaneously developed a second spontaneous E85K parC mutation and resistance following prolonged incubation in 4 mg/L levofloxacin for an extra 24–48 h. Continued AST surveillance and investigation is required to understand how gyrA QRDR mutations predispose M. hominis to rapid spontaneous mutation and fluoroquinolone resistance, absent from other susceptible isolates. The unusually high prevalence of polymorphisms in M. hominis also warrants increased genomics’ surveillance.

Determination of In Vitro Antimicrobial Susceptibility for Lefamulin (Pleuromutilin) for Ureaplasma Spp. and Mycoplasma hominis

Lefamulin is the first of the pleuromutilin class of antimicrobials to be available for therapeutic use in humans. Minimum inhibitory concentrations of lefamulin were determined by microbroth dilution for 90 characterised clinical isolates (25 Ureaplasma parvum, 25 Ureaplasma urealyticum, and 40 Mycoplasma hominis). All Mycoplasma hominis isolates possessed lefamulin MICs of ≤0.25 mg/L after 48 h (MIC_50/90 of 0.06/0.12 mg/L), despite an inherent resistance to macrolides; while Ureaplasma isolates had MICs of ≤2 mg/L after 24 h (MIC_50/90 of 0.25/1 mg/L), despite inherent resistance to clindamycin. Two U. urealyticum isolates with additional A2058G mutations of 23S rRNA, and one U. parvum isolate with a R66Q67 deletion (all of which had a combined resistance to macrolides and clindamycin) only showed a 2-fold increase in lefamulin MIC (1–2 mg/L) relative to macrolide-susceptible strains. Lefamulin could be an effective alternative antimicrobial for treating Ureaplasma spp. and Mycoplasma hominis infections irrespective of intrinsic or acquired resistance to macrolides, lincosamides, and ketolides. Based on this potent in vitro activity and the known good, rapid, and homogenous tissue penetration of female and male urogenital tissues and glands, further exploration of clinical efficacy of lefamulin for the treatment of Mycoplasma and Ureaplasma urogenital infections is warranted.

Phenotypic Antimicrobial Susceptibility and Genotypic Characterization of Clinical Ureaplasma Isolates Circulating in Shanghai, China

There is a growing global concern regarding the rise of antimicrobial resistance among Ureaplasma spp. isolates. However, studies on the antimicrobial susceptibility profiles, resistance mechanisms, and clonality of Ureaplasma spp. clinical isolates are still limited and cover only some geographic regions. Firstly, Ureaplasma species from the urogenital tracts of patients in Shanghai, China, were isolated by using the culture medium (A8 and 10B broth), and identified the genotype by polymerase chain reaction (PCR). Secondly, the antimicrobial susceptibility tests were determined by using broth microdilution assay. Then, the resistance genetic determinants to fluoroquinolones (FQs), macrolides, and tetracyclines were investigated through PCR/DNA sequencing. Finally, the molecular epidemiology of Ureaplasma species was studied by multilocus sequence typing (MLST). Among 258 isolates, Ureaplasma parvum (UPA) and Ureaplasma urealyticum (UUR) were found in 226 (87.60%) and 32 (12.40%) isolates, respectively. The minimum inhibitory concentrations (MICs) of 258 Ureaplasma spp. strains ranged from 0.015 to 64μg/ml for all 11 kinds of antimicrobials. Regardless of species, the isolates were most sensitive to AZI (1.94%), JOS (3.49%), and CLA (4.23%). Among them, there were 39 (15.12%) multidrug-resistant (MDR) strains, including 32 UPA isolates. The resistance rates of UPA to CIP (91.59%), and ROX (36.28%) were significantly higher than those of UUR. Twenty six FQ-resistant isolates had amino acid substitutions in gyrA and in parC (Ser83Leu). Mutations were detected in genes encoding ribosomal proteins L4 (Thr84Ile) and L22 (Ser81Pro) in macrolide-resistant isolates. Tet(M) was found in four UPA isolates. These mutations were mainly found in UPA isolates. Sequence type 1 (ST1) was the predominant ST, which contained 18 isolates. In conclusion, this study showed a higher resistance rate (especially to ROX and CIP), higher substitution rate, and higher MDR rate among UPA strains. The most active antimicrobial agents were AZI, JOS, and CLA. Identifying UPA or UUR in clinical isolates could help clinicians to choose appropriate drugs for treatment. The main resistance mechanisms may involve gene substitution of Ser83Leu in parC and Ser81Pro in L22. ST1 was the predominant ST of Ureaplasma isolates with MDR to FQs and macrolides in Shanghai, China.

Evaluation of the MYCOPLASMA IST3 urogenital mycoplasma assay in an international multicentre trial

OBJECTIVES

To evaluate the accuracy, susceptibility and specificity of MYCOPLASMA IST3, the next generation of the most popular culture-based in vitro diagnostic device designed to detect, identify and test the susceptibility of urogenital mycoplasma infections.

METHODS

MYCOPLASMA IST3 was evaluated against culture- and molecular-based gold standard methodologies to detect, identify, enumerate and determine antimicrobial resistance for Mycoplasma hominis and Ureaplasma species in 516 clinical samples collected across France, Serbia and the UK. Sample types included vulvovaginal/endocervical or urethral swabs (dry swab or eSwab®), semen and urine samples, which included blinded analysis following addition of a panel of 80 characterized control strains.

RESULTS

Overall species identification was excellent for both Ureaplasma spp. (98.4% sensitivity, 99.7% specificity) and M. hominis (95.7% sensitivity, 100% specificity) relative to combined colony morphology on agar and quantitative PCR standards. Non-dilution-based bacterial load estimation by the assay was accurate between 83.7% (M. hominis) and 86.3% (Ureaplasma spp.) of the time (increased to 94.2% and 100%, respectively, if ±10-fold variance was allowed) relative to colonies counted on agar. Resistance accuracy for Ureaplasma spp. varied from gold standards for only 11/605 of individual tests (major error rate = 1.8%) and for 14/917 individual tests for M. hominis (major error rate = 1.5%).

CONCLUSIONS

The redesigned MYCOPLASMA IST3 assay eliminated previous shortcomings by providing independent accurate resistance screening of M. hominis and Ureaplasma species, even in mixed infections, with CLSI-compliant thresholds. Specificity, sensitivity and enumeration estimates correlated closely with the confirmatory methods.

In vitro activities of acetylmidecamycin and other antimicrobials against human macrolide-resistant Mycoplasma pneumoniae isolates

OBJECTIVES

To assess the in vitro activities of acetylmidecamycin, a 16-membered macrolide, and 11 other antimicrobial agents against human mycoplasmas.

METHODS

A total of 187 clinical isolates, Mycoplasma pneumoniae (n = 110), Mycoplasma hominis (n = 26) and Ureaplasma species (n = 51), were included in this study. The MICs of 12 antimicrobial agents, including acetylmidecamycin, thiamphenicol, chloramphenicol and some other macrolides, fluoroquinolones and tetracyclines, for these clinical isolates were determined by the broth microdilution method.

RESULTS

For M. pneumoniae, the MIC90 values of the tested macrolides were: acetylmidecamycin (1 mg/L)<josamycin (4 mg/L)<midecamycin (8 mg/L)<azithromycin (16 mg/L)<erythromycin (>128 mg/L). Thiamphenicol and chloramphenicol had the same MIC90 (2 mg/L). For Ureaplasma species, the MIC90 values were: acetylmidecamycin (0.25 mg/L)<josamycin (0.5 mg/L)=midecamycin<azithromycin (1 mg/L)=erythromycin. Chloramphenicol had a lower MIC90 (2 mg/L) than that of thiamphenicol (4 mg/L). For M. hominis, the MIC90 values were: acetylmidecamycin (0.25 mg/L)<josamycin (0.5 mg/L)<midecamycin (2 mg/L)<azithromycin (>128 mg/L)=erythromycin. The MIC90 values of chloramphenicol and thiamphenicol were 2 and 4 mg/L, respectively.

CONCLUSIONS

The results indicated that acetylmidecamycin and thiamphenicol are active in vitro against the most common mycoplasma species infecting humans, including those resistant to macrolides and fluoroquinolones. Acetylmidecamycin and thiamphenicol might be a promising option for clinicians to treat infections caused by Mycoplasma and Ureaplasma spp., particularly macrolide-resistant M. pneumoniae in paediatrics and fluoroquinolone-resistant M. hominis in adults. Further investigation of their clinical roles in treating infections caused by these organisms is warranted.

Antimicrobial resistance in clinical isolates of Ureaplasma spp. from samples in Germany

Ureaplasma urealyticum and U parvum are mollicutes species that colonize the urogenital tract of many asymptomatic persons but are also thought to be associated with symptomatic infections. Using 170 strains isolated between 2016 and 2019 in a German university hospital, resistance was tested by a combination of commercial tests, molecular methods and determination of minimal inhibitory concentrations. Rates of resistance to macrolides, tetracyclines and fluoroquinolones were 0%, 4.1% and 7.1%, respectively.

Regulation of tert-Butyl Hydroperoxide Resistance by Chromosomal OhrR in A. baumannii ATCC 19606

In this study, we show that Acinetobacter baumannii ATCC 19606 harbors two sets of ohrR-ohr genes, respectively encoded in chromosomal DNA and a pMAC plasmid. We found no significant difference in organic hydroperoxide (OHP) resistance between strains with or without pMAC. However, a disk diffusion assay conducted by exposing wild-type, ∆ohrR-C, C represented gene on chromosome, or ∆ohr-C single mutants, or ∆ohrR-C∆ohr-C double mutants to tert-butyl hydroperoxide (tBHP) found that the ohrR-p-ohr-p genes, p represented genes on pMAC plasmid, may be able to complement the function of their chromosomal counterparts. Interestingly, ∆ohr-C single mutants generated in A. baumannii ATCC 17978, which does not harbor pMAC, demonstrated delayed exponential growth and loss of viability following exposure to 135 μg of tBHP. In a survival assay conducted with Galleria mellonella larvae, these mutants demonstrated almost complete loss of virulence. Via an electrophoretic mobility shift assay (EMSA), we found that OhrR-C was able to bind to the promoter regions of both chromosomal and pMAC ohr-p genes, but with varying affinity. A gain-of-function assay conducted in Escherichia coli showed that OhrR-C was not only capable of suppressing transformed ohr-C genes but may also repress endogenous enzymes. Taken together, our findings suggest that chromosomal ohrR-C-ohr-C genes act as the major system in protecting A. baumannii ATCC 19606 from OHP stresses, but the ohrR-p-ohr-p genes on pMAC can provide a supplementary protective effect, and the interaction between these genes may affect other aspects of bacterial viability, such as growth and virulence.

Resistance to tetracyclines among clinical isolates of Mycoplasma hominis and Ureaplasma species: a systematic review and meta-analysis

BACKGROUND

Resistance to tetracyclines, the first-line treatment for urogenital infections caused by Mycoplasma hominis and Ureaplasma species, is increasing worldwide. The aim of the present study was to determine the global status of resistance to this class of antibiotics.

METHODS

Electronic databases were searched using keywords including 'Mycoplasma', 'Mycoplasma hominis', 'M. hominis', 'Ureaplasma', 'Ureaplasma urealyticum', 'Ureaplasma parvum', 'U. urealyticum', 'U. parvum', 'Ureaplasma species', 'resistance', 'antibiotic resistance', 'antibiotic susceptibility', 'antimicrobial resistance', 'antimicrobial susceptibility', 'tetracycline', 'doxycycline' and 'minocycline'. Finally, after some exclusions, 37 studies from different countries were included in the study and meta-analysis was performed on the data collected.

RESULTS

The midrange resistance rates for M. hominis and U. urealyticum/parvum to tetracycline, doxycycline and minocycline were 50.0%, 9.0% and 16.7% and 43.3%, 28.6% and 9.0%, respectively. A high level of heterogeneity was observed in all studies (I2 > 50%, P value < 0.05), except those representing doxycycline resistance in M. hominis isolates (I2 = 39.1%, P  = 0.02). No evidence of publication bias was observed in the studies and neither Egger's test nor Begg's test showed significant publication bias.

CONCLUSIONS

The results of the present study show that the overall resistance to tetracyclines is relatively high and prevalent among M. hominis and Ureaplasma species throughout the world. This highlights the importance of and necessity for regional and local antibiotic susceptibility testing before treatment choice as well as development of newer generations of tetracyclines to prevent antibiotic misuse, emergence and spread of resistant strains and, finally, the failure of treatment.

Molecular diagnostic of Ureaplasma urealyticum presence and tetracycline resistance in urine samples

Sexually transmitted infections (STIs) are among the most common infections in Romania. Infection with Ureaplasma urelyticum is one of the major causes of STIs and can cause serious complications. Although tetracycline is the drug commonly used to treat infections caused by U. urealyticum, several studies indicate the emergence and rapid development of strains resistant to these antibiotics in the United States or Europe. Tetracycline resistance in bacteria is encoded by a number of different genetic determinants but in mycoplasmas the only tetracycline resistance determinant that has been reported is the tetM gene. Tetracycline resistance among Ureaplasma spp. is associated with the presence of the horizontally acquired tetM resistance gene. Our study on bacterial DNA aimed to determine the presence of tetracycline-resistant U. urealyticum strains, by identifying the presence of the tetM gene. We used first void urine samples from 622 STI-suspected subjects. DNA was extracted, purified and amplified via PCR for the simultaneous detection of 6 STIs. 68 patients were diagnosed with U. urealyticum. DNA obtained from these samples was amplified using the tetM gene and U. urealyticum - specific urease gene primers. The urease gene was amplified in all samples, confirming the presence of U. urealyticum. The tetM gene was amplified in 2 samples considered tetracycline-resistant strains. The study confirmed the presence of U. urealyticum strains resistant to tetracycline in Romania. The employed technique can produce quick results both for U. urealyticum detection and determination of its resistance to tetracycline using a single easy-to-collect biological sample.

Antimicrobial activity of enacyloxin IIa and gladiolin against the urogenital pathogens Neisseria gonorrhoeae and Ureaplasma spp

AIMS

To determine the antimicrobial activity of enacyloxin IIa and gladiolin against Neisseria gonorrhoeae and Ureaplasma spp.

METHODS AND RESULTS

The Burkholderia polyketide antibiotics enacyloxin IIa and gladiolin were tested against 14 N. gonorrhoeae and 10 Ureaplasma spp. isolates including multidrug-resistant N. gonorrhoeae isolates WHO V, WHO X and WHO Z as well as macrolide, tetracycline and ciprofloxacin-resistant ureaplasmas. Susceptibility testing of N. gonorrhoeae was carried out by agar dilution, whereas broth micro-dilution and growth kinetic assays were used for Ureaplasma spp. The MIC range for enacyloxin IIa and gladiolin against N. gonorrhoeae was 0·015-0·06 mg l^-1 and 1-2 mg l^-1 respectively. The presence of resistance to front line antibiotics had no effect on MIC values. The MIC range for enacyloxin IIa against Ureaplasma spp. was 4-32 mg l^-1 with a clear dose-dependent effect when observed using a growth kinetic assay. Gladiolin had no antimicrobial activity on Ureaplasma spp. at 32 mg l^-1 and limited impact on growth kinetics.

CONCLUSIONS

Enacyloxin IIa and gladiolin antibiotics have antimicrobial activity against a range of antibiotic susceptible and resistant N. gonorrhoeae and Ureaplasma isolates.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study highlights the potential for a new class of antimicrobial against pathogens in which limited antibiotics are available. Development of these compounds warrants further investigation in the face of emerging extensively drug-resistant strains.

Rare case of Ureaplasma parvum septic arthritis in an immunocompetent patient

Mycoplasmatacea family comprises two genera: Mycoplasma and Ureaplasma Ureaplasma parvum (previously known as U. urealyticum biovar 1) commonly colonises the urogenital tract in humans. Although Ureaplasma species have well-established pathogenicity in urogenital infections, its involvement in septic arthritis has been limited to prosthetic joint infections and immunocompromised individuals. We present a rare case of native right knee infection due to U. parvum identified using next-generation sequencing of microbial cell-free DNA testing and confirmed with PCR assays. This rare case of Ureaplasma septic arthritis was diagnosed using newer next-generation DNA sequencing diagnostic modalities and a literature review of prior cases, antibiotic coverage and antimicrobial resistance is incorporated as part of the discussion.

MYCO WELL D-ONE detection of Ureaplasma spp. and Mycoplasma hominis in sexual health patients in Wales

The genital mycoplasmas are a unique group of inherently antibiotic-resistant sexually transmitted bacteria, often associated with non-gonococcal urethritis and bacterial vaginosis. The MYCO WELL D-ONE is a culture-based assay that aims to detect these organisms whilst concurrently screening them for antibiotic resistance. Urine and/or swabs from 856 informed and consented participants attending Welsh sexual health clinics were subjected to MYCO WELL D-ONE analysis, alongside qPCR and culture titration methodologies to determine sensitivity, specificity, PPV, NPV and accuracy. Resistance was confirmed by CLSI-compliant susceptibility testing and genetic mechanisms determined. The MYCO WELL D-ONE displayed a sensitivity and specificity of 91.98% and 96.44% for the detection of Ureaplasma spp., with sensitivity and specificity values of 78.23% and 98.84% for Mycoplasma hominis, compared with qPCR. Swabs harboured significantly greater bacterial loads than urine samples for both Ureaplasma spp. and M. hominis. Levofloxacin resistance rates, mediated by Ser83Leu mutation in ParC, for Ureaplasma spp. were 0.54%. Tetracycline resistance rates, mediated by tet(M), were 0.54% and 2% for Ureaplasma spp. and M. hominis, respectively; sequence analysis of tet(M)-positive Ureaplasma spp. and M. hominis strains isolated from a single individual confirmed separate resistance gene origins. The MYCO WELL D-ONE is a sensitive and specific assay for the detection of Ureaplasma spp. and M. hominis in genitourinary medicine samples, facilitating the accurate detection of these organisms within low-technology environments. While good for antibiotic resistance screening, accurate confirmation by MIC determination or molecular methods are required, and more optimally performed on urine samples.

Antimicrobial resistance, genetic characterization, and molecular epidemiology of Ureaplasma species in males with infertility

This study aimed to study the antimicrobial resistance, genetic characterization, and molecular epidemiology of Ureaplasma species in order to provide clinicians sufficient data to select optimal strategies of treatment for genitourinary tract infections of infertile male patients. Firstly, a total of 817 clinical semen specimens were detected for Ureaplasma species by molecular detection. Secondly, culture and identification of Ureaplasma species were achieved by using Mycoplasma ICS Test, and the antimicrobial susceptibility tests were determined by using broth microdilution assay. Then, the tetracycline resistance genetic determinants in Ureaplasma species were identified by PCR, and the fluoroquinolone and macrolide resistance genetic determinants were identified by DNA sequencing. Finally, the molecular epidemiology of Ureaplasma species was studied by both multilocus sequence typing (MLST) and expanded MLST (eMLST) schemes. Among the 817 semen specimens, 320 (39.17%) specimens were positive for Ureaplasma species. The percentages of resistance in 320 isolates against LEV, MXF, TET, and ERY were 47.5%, 39.38%, 19.69%, and 3.75%, respectively. The tet(M) and int-Tn genes were detected positive in all the tetracycline-resistant isolates. One macrolide-resistant UU isolate had a novel amino acid alteration (R66T) in L4 ribosomal protein and another UU isolate harbored a novel alteration (S109T) in L22. In fluoroquinolone-resistant isolates, S83L substitution in the ParC was predominant. In this area, ST22 and eST16 were the most prevalent ST and eST, respectively. One ST and 3 eSTs were newly identified in this study. This study has demonstrated that ERY can be first-line therapy for Ureaplasma species infections.

Comparative genomics of three clinical Ureaplasma species: analysis of their core genomes and multiple-banded antigen locus

Aim: To compare the genome sequences among clinical and American-Type Culture Collection Ureaplasma strains and to reveal the potential molecular mechanisms of multiple banded antigen (MBA) variation. Materials & methods: Two strains of Ureaplasma urealyticum 132 and 315 and one strain of Ureaplasma parvum 106 isolated from infertile males were sequenced using Illumina and Nanopore technologies. Comparative genomic analysis was performed of the three strains and two American-Type Culture Collection strains. Results & conclusion: The Ureaplasma species shared a core genome. Strains 132 and 315 shared a distant relationship with previously sequenced Ureaplasma spp. The MBA locus is more informative for studying MBA mutations than is the mba gene alone. The mechanisms of MBA variation are more flexible and complex than previously reported. The variation in MBA is not limited to the mba gene but occurs in other genes within the MBA locus.

Cervical epithelial damage promotes Ureaplasma parvum ascending infection, intrauterine inflammation and preterm birth induction in mice

Around 40% of preterm births are attributed to ascending intrauterine infection, and Ureaplasma parvum (UP) is commonly isolated in these cases. Here we present a mouse model of ascending UP infection that resembles human disease, using vaginal inoculation combined with mild cervical injury induced by a common spermicide (Nonoxynol-9, as a surrogate for any mechanism of cervical epithelial damage). We measure bacterial load in a non-invasive manner using a luciferase-expressing UP strain, and post-mortem by qPCR and bacterial titration. Cervical exposure to Nonoxynol-9, 24 h pre-inoculation, facilitates intrauterine UP infection, upregulates pro-inflammatory cytokines, and increases preterm birth rates from 13 to 28%. Our results highlight the crucial role of the cervical epithelium as a barrier against ascending infection. In addition, we expect the mouse model will facilitate further research on the potential links between UP infection and preterm birth.

In vitro Activities of Nemonoxacin and Other Antimicrobial Agents Against Human Mycoplasma and Ureaplasmas Isolates and Their Defined Resistance Mechanisms

Nemonoxacin, a newly developed non-fluorinated quinolone (NFQ), selectively inhibits bacterial DNA topoisomerase activity. However, its activities against Mycoplasmas have rarely been studied to date. Herein, the activities of nemonoxacin were evaluated against clinical isolates of 50 Mycoplasma pneumoniae, 20 Mycoplasma hominis, and 77 Ureaplasma spp., and they were compared to fluoroquinolones, tetracyclines, and macrolides. Nemonoxacin MICs (μg/ml) ranged from 0.03 to 0.25 for M. pneumoniae, 0.25 to 8 for M. hominis, and 0.06 to >16 for Ureaplasma spp., and all of the ranges are similar to those of fluoroquinolones. The activity of nemonoxacin against Mycoplasmas was not affected by resistance to macrolides in the strains tested, but it seems to have the same resistant mechanism as fluoroquinolones. In addition, minimum bactericidal concentrations (MBC) of nemonoxacin to M. pneumoniae were within two dilutions of the MIC values, indicating a bactericidal effect on M. pneumoniae. Nemonoxacin merits further study for treating infections caused by these organisms.

A new class of antibacterials, the imidazopyrazinones, reveal structural transitions involved in DNA gyrase poisoning and mechanisms of resistance

Imidazopyrazinones (IPYs) are a new class of compounds that target bacterial topoisomerases as a basis for their antibacterial activity. We have characterized the mechanism of these compounds through structural/mechanistic studies showing they bind and stabilize a cleavage complex between DNA gyrase and DNA ('poisoning') in an analogous fashion to fluoroquinolones, but without the requirement for the water-metal-ion bridge. Biochemical experiments and structural studies of cleavage complexes of IPYs compared with an uncleaved gyrase-DNA complex, reveal conformational transitions coupled to DNA cleavage at the DNA gate. These involve movement at the GyrA interface and tilting of the TOPRIM domains toward the scissile phosphate coupled to capture of the catalytic metal ion. Our experiments show that these structural transitions are involved generally in poisoning of gyrase by therapeutic compounds and resemble those undergone by the enzyme during its adenosine triphosphate-coupled strand-passage cycle. In addition to resistance mutations affecting residues that directly interact with the compounds, we characterized a mutant (D82N) that inhibits formation of the cleavage complex by the unpoisoned enzyme. The D82N mutant appears to act by stabilizing the binary conformation of DNA gyrase with uncleaved DNA without direct interaction with the compounds. This provides general insight into the resistance mechanisms to antibiotics targeting bacterial type II topoisomerases.

Prevalence and Antimicrobial Susceptibility of Ureaplasma spp. and Mycoplasma hominis in Asymptomatic Individuals in Korea

This study investigated the prevalence and antibiotic resistance of Ureaplasma spp. and Mycoplasma hominis isolated from asymptomatic individuals in Korea. Endocervical swabs from women and urine from men, from a total of 5,781 asymptomatic individuals, were analyzed using a Mycoplasma IST2 Kit. Of the 4,825 specimens tested from females, 486 (10.1%) were positive culture. In these positive specimens, 437 (9.1%) were positive only for Ureaplasma spp., 17 (0.4%) were positive only for M. hominis, and 32 (0.7%) were positive for both Ureaplasma spp. and M. hominis. In males, of the 956 tested specimens, only 4 (0.42%) were positive for Ureaplasma spp. and no M. hominis colonization was identified. In antimicrobial susceptibility tests, more than 93.2% of both M. hominis and Ureaplasma spp. was susceptible to tetracycline, doxycycline, josamycin, and pristinamycin. However, M. hominis isolates were found to be highly resistant to erythromycin, azithromycin, and clarithromycin (82.4%, 70.6%, and 76.5%, respectively). Ofloxacin and ciprofloxacin, which have recently exhibited increasing resistance rates, showed rates of 17.7% and 35.3%, respectively, in M. hominis, and 50.6% and 27.4%, respectively, in Ureaplasma spp. In conclusion, accurate antimicrobial susceptibility tests of the genital mycoplasmas should be conducted for each case to select the appropriate antibiotics. Fluoroquinolone-based drugs should be avoided in the initial treatment of urogenital mycoplasmas because of the increasing rate of resistance to quinolones, although the susceptibility to tetracycline remains high in Korea.

Antibiotic resistance among Ureaplasma spp. isolates: cause for concern?

There is growing global concern regarding the rise of antibiotic-resistant organisms. Many of these reports have focused on various Gram-positive and Gram-negative pathogens, with little attention to the genus Ureaplasma. Ureaplasma spp. are associated with numerous infectious diseases affecting pregnant women, neonates and the immunocompromised. Treatment options are extremely limited due to high levels of intrinsic resistance resulting from the unique physiology of these organisms and further restricted in cases of the developing fetus or neonate, often limiting therapeutic options to predominantly macrolides or rarely fluoroquinolones. The increasing presence of macrolide- and fluoroquinolone-resistant strains among neonatal infections may result in pan-drug resistance and potentially untreatable conditions. Here, we review the requirements for accurate measurement of antimicrobial susceptibility, provide a comprehensive review of the antimicrobial resistance (AMR) for Ureaplasma species in the literature and contextualize these results relative to some investigators' reliance on commercial kits that are not CLSI compliant when determining AMR. The dramatic variation in the resistance patterns and impact of high levels of AMR amongst neonatal populations suggests the need for continued surveillance. Commercial kits represent an excellent tool for initial antibiotic susceptibility determination and screening. However, AMR reporting must utilize internationally standardized methods, as high-titre samples, or Mycoplasma hominis-contaminated samples routinely give false AMR results. Furthermore, there is a requirement for future reports to determine the underlying AMR mechanisms and determine whether expanding AMR is due to spontaneous mutation, transmission of resistance genes on mobile elements or selection and expansion of resistant clones.

Ureaplasma parvum genotype, combined vaginal colonisation with Candida albicans, and spontaneous preterm birth in an Australian cohort of pregnant women

BACKGROUND

Detection of Ureaplasma, Mycoplasma and Candida spp. in the vagina during pregnancy has previously been associated with preterm birth (PTB). However, the prevalence of these microorganisms and the associated obstetric risks (likely to be population-specific) have not been determined in Australian women; furthermore, in the case of Ureaplasma spp., very few studies have attempted characterisation at the species level and none have examined genotype/serovar status to further refine risk assessment.

METHODS

In order to address these issues we sampled the vaginal fluid of 191 pregnant Australian women at three time points in pregnancy. Culture methods were used for detection of Ureaplasma spp. and Candida spp., and real-time PCR was used for speciation of U. parvum and U. urealyticum, non-albicans Candida spp., Mycoplasma hominis and Mycoplasma genitalium. High-resolution melt PCR was used to genotype U. parvum. Data on various lifestyle factors (including sex during pregnancy and smoking), antimicrobial use and pregnancy outcome were collected on all participants. Chi-square tests were used to assess the association of vaginal microorganisms with PTB.

RESULTS

Detection of Ureaplasma spp. was higher among spontaneous PTB cases, specifically in the presence of U. parvum [77 % preterm (95 % confidence interval (CI) 50-100 %) vs. 36 % term (CI: 29-43 %), p = 0.004], but not U. urealyticum. The association with PTB strengthened when U. parvum genotype SV6 was detected (54 % preterm (CI: 22-85 %) vs. 15 % term (CI: 10-20 %), p = 0.002); this genotype was also present in 80 % (4/5) of cases of PTB <34 weeks gestation. When present with Candida albicans in the same sample, the association with PTB remained strong for both U. parvum [46 % preterm (CI: 15-78 %) vs. 13 % term (CI: 8-18 %), p = 0.005] and U. parvum genotype SV6 [39 % preterm (CI: 8-69 %) vs. 7 % term (CI: 3-11 %), p = 0.003]. With the exception of Candida glabrata, vaginal colonisation status for all organisms was stable throughout pregnancy. Smoking significantly increased the likelihood of detection of all target organisms.

CONCLUSIONS

These data suggest that the presence of different species and serovars of Ureaplasma spp. in the vagina confers an increased risk of spontaneous PTB, findings which may be useful in risk assessment for identifying women who would benefit from antimicrobial treatment.

Isolation of Separate Ureaplasma Species From Endotracheal Secretions of Twin Patients

Isolation of Ureaplasma spp. from preterm neonates and the association with development of bronchopulmonary dysplasia has been previously investigated. However, few studies have contrasted the nature of infection in twins. In this article, we report that dizygotic twins (1 girl, 1 boy) born at 24 weeks gestation both yielded culturable Ureaplasma from endotracheal secretions. The samples were part of a serial blind collection cohort of ventilated premature neonates, and analysis of repeat cultures showed stable, separate infections over a period of 17 and 21 days, respectively. Immunoblot and probe-specific quantitative polymerase chain reaction analysis determined that Twin 1 was solely infected with Ureaplasma parvum (specifically, serovar 6 by gene sequencing), whereas Twin 2 was solely infected with Ureaplasma urealyticum (specifically, genotype A- serovars 2, 5, and 8 by gene sequencing). Immunoblot analysis found that the major surface antigen (multiple-banded antigen) altered relative mass for both strains during the course of infection. Quantitative polymerase chain reaction analysis of extracted endotracheal aspirates confirmed no evidence of mixed infection for either twin. Failure of sentinel ventilated preterm infants on the same ward to acquire Ureaplasma infection after the first week of birth suggests no cot-to-cot transfer of Ureaplasma infection occurred. This study demonstrated not only a contrasting clinical outcome for a set of twins infected with 2 separate species of Ureaplasma, but also the first real-time demonstration of multiple-banded antigen alteration and evolution of Ureaplasma over the course of a clinical infection.

Antimicrobial Susceptibility and Clonality of Clinical Ureaplasma Isolates in the United States

Ureaplasma urealyticum and Ureaplasma parvum are pathogens involved in urogenital tract and intrauterine infections and also in systemic diseases in newborns and immunosuppressed patients. There is limited information on the antimicrobial susceptibility and clonality of these species. In this study, we report the susceptibility of 250 contemporary isolates of Ureaplasma (202 U. parvum and 48 U. urealyticum isolates) recovered at Mayo Clinic, Rochester, MN. MICs of doxycycline, azithromycin, ciprofloxacin, tetracycline, erythromycin, and levofloxacin were determined by broth microdilution, with MICS of the last three interpreted according to CLSI guidelines. Levofloxacin resistance was found in 6.4% and 5.2% of U. parvum and U. urealyticum isolates, respectively, while 27.2% and 68.8% of isolates, respectively, showed ciprofloxacin MICs of ≥4 μg/ml. The resistance mechanism of levofloxacin-resistant isolates was due to mutations in parC, with the Ser83Leu substitution being most frequent, followed by Glu87Lys. No macrolide resistance was found among the 250 isolates studied; a single U. parvum isolate was tetracycline resistant. tet(M) was found in 10 U. parvum isolates, including the single tetracycline-resistant isolate, as well as in 9 isolates which had low tetracycline and doxycycline MICs. Multilocus sequence typing (MLST) performed on a selection of 46 isolates showed high diversity within the clinical Ureaplasma isolates studied, regardless of antimicrobial susceptibility. The present work extends previous knowledge regarding susceptibility to antimicrobial agents, resistance mechanisms, and clonality of Ureaplasma species in the United States.

Differential recognition of the multiple banded antigen isoforms across Ureaplasma parvum and Ureaplasma urealyticum species by monoclonal antibodies

Two separate species of Ureaplasma have been identified that infect humans: Ureaplasma parvum and Ureaplasma urealyticum. Most notably, these bacteria lack a cell wall and are the leading infectious organism associated with infection-related induction of preterm birth. Fourteen separate representative prototype bacterial strains, called serovars, are largely differentiated by the sequence of repeating units in the C-terminus of the major surface protein: multiple-banded antigen (MBA). Monoclonal antibodies that recognise single or small groups of serovars have been previously reported, but these reagents remain sequestered in individual research laboratories. Here we characterise a panel of commercially available monoclonal antibodies raised against the MBA and describe the first monoclonal antibody that cross-reacts by immunoblot with all serovars of U. parvum and U. urealyticum species. We also describe a recombinant MBA expressed by Escherichia coli which facilitated further characterisation by immunoblot and demonstrate immunohistochemistry of paraffin-embedded antigens. Immunoblot reactivity was validated against well characterised previously published monoclonal antibodies and individual commercial antibodies were found to recognise all U. parvum strains, only serovars 3 and 14 or only serovars 1 and 6, or all strains belonging to U. parvum and U. urealyticum. MBA mass was highly variable between strains, consistent with variation in the number of C-terminal repeats between strains. Antibody characterisation will enable future investigations to correlate severity of pathogenicity to MBA isoform number or mass, in addition to development of antibody-based diagnostics that will detect infection by all Ureaplasma species or alternately be able to differentiate between U. parvum, U. urealyticum or mixed infections.

Antibiotic Resistance among Clinical Ureaplasma Isolates Recovered from Neonates in England and Wales between 2007 and 2013

Ureaplasma spp. are associated with numerous clinical sequelae with treatment options being limited due to patient and pathogen factors. This report examines the prevalence and mechanisms of antibiotic resistance among clinical strains isolated from 95 neonates, 32 women attending a sexual health clinic, and 3 patients under investigation for immunological disorders, between 2007 and 2013 in England and Wales. MICs were determined by using broth microdilution assays, and a subset of isolates were compared using the broth microdilution method and the Mycoplasma IST2 assay. The underlying molecular mechanisms for resistance were determined for all resistant isolates. Three isolates carried the tet(M) tetracycline resistance gene (2.3%; confidence interval [CI], 0.49 to 6.86%); two isolates were ciprofloxacin resistant (1.5%; CI, 0.07 to 5.79%) but sensitive to levofloxacin and moxifloxacin, while no resistance was seen to any macrolides tested. The MIC values for chloramphenicol were universally low (2 μg/ml), while inherently high-level MIC values for gentamicin were seen (44 to 66 μg/ml). The Mycoplasma IST2 assay identified a number of false positives for ciprofloxacin resistance, as the method does not conform to international testing guidelines. While antibiotic resistance among Ureaplasma isolates remains low, continued surveillance is essential to monitor trends and threats from importation of resistant clones.

Antibiotic Susceptibility and Sequence Type Distribution of Ureaplasma Species Isolated from Genital Samples in Switzerland

Antibiotic resistance in Ureaplasma urealyticum/Ureaplasma parvum and Mycoplasma hominis is an issue of increasing importance. However, data regarding the susceptibility and, more importantly, the clonality of these organisms are limited. We analyzed 140 genital samples obtained in Bern, Switzerland, in 2014. Identification and antimicrobial susceptibility tests were performed by using the Mycoplasma IST 2 kit and sequencing of 16S rRNA genes. MICs for ciprofloxacin and azithromycin were obtained in broth microdilution assays. Clonality was analyzed with PCR-based subtyping and multilocus sequence typing (MLST), whereas quinolone resistance and macrolide resistance were studied by sequencing gyrA, gyrB, parC, and parE genes, as well as 23S rRNA genes and genes encoding L4/L22 ribosomal proteins. A total of 103 samples were confirmed as positive for U. urealyticum/U. parvum, whereas 21 were positive for both U. urealyticum/U. parvum and M. hominis. According to the IST 2 kit, the rates of nonsusceptibility were highest for ciprofloxacin (19.4%) and ofloxacin (9.7%), whereas low rates were observed for clarithromycin (4.9%), erythromycin (1.9%), and azithromycin (1%). However, inconsistent results between microdilution and IST 2 kit assays were recorded. Various sequence types (STs) observed previously in China (ST1, ST2, ST4, ST9, ST22, and ST47), as well as eight novel lineages, were detected. Only some quinolone-resistant isolates had amino acid substitutions in ParC (Ser83Leu in U. parvum of serovar 6) and ParE (Val417Thr in U. parvum of serovar 1 and the novel Thr417Val substitution in U. urealyticum). Isolates with mutations in 23S rRNA or substitutions in L4/L22 were not detected. This is the first study analyzing the susceptibility of U. urealyticum/U. parvum isolates in Switzerland and the clonality outside China. Resistance rates were low compared to those in other countries. We hypothesize that some hyperepidemic STs spread worldwide via sexual intercourse. Large combined microbiological and clinical studies should address this important issue.

In vitro activity of solithromycin and its metabolites, CEM-214 and N-acetyl-CEM-101, against 100 clinical Ureaplasma spp. isolates compared with azithromycin

There is a strong association between vaginal and/or amniotic fluid Ureaplasma spp. colonisation and risk of preterm birth. The novel fluoroketolide antibiotic solithromycin (CEM-101) is active against Ureaplasma spp. in vitro. Evidence from ex vivo and in vivo models suggests that, unlike most macrolide antibiotics, solithromycin readily crosses the placenta. Solithromycin metabolism varies according to species; in pregnant sheep, the bioactive metabolites CEM-214 and N-acetyl-CEM-101 (NAc-CEM-101) have been shown to accumulate in the amniotic cavity following maternal solithromycin administration, potentially contributing to its antimicrobial effects. To determine the antimicrobial activity of these metabolites against Ureaplasma spp., the effects of solithromycin, CEM-214, NAc-CEM-101 and the comparator azithromycin were tested on a collection of 100 clinical Ureaplasma spp. isolates from the UK and Australia using a modified 96-well broth microdilution method. MIC90 values observed for the combined cohort were: solithromycin, 0.125 mg/L; CEM-214, 0.5mg/L; NAc-CEM-101, 0.5mg/L; and azithromycin, 2mg/L. Solithromycin showed 34-fold greater activity against Ureaplasma spp. isolates than azithromycin, whilst CEM-214 and NAc-CEM-101 possessed ca. 22% and 17% of the activity of solithromycin, respectively, significantly greater than that of azithromycin. One bacterial isolate showed resistance to azithromycin (MIC=16 mg/L) but had a much lower MIC for solithromycin (MIC=0.25mg/L). In conclusion, the metabolites of solithromycin had reduced, but still potent, activity against 100 clinical Ureaplasma spp. isolates in vitro. This may be important in some instances such as pregnancy, however studies to determine levels of the metabolites in these settings are required.

In vitro activity of five quinolones and analysis of the quinolone resistance-determining regions of gyrA, gyrB, parC, and parE in Ureaplasma parvum and Ureaplasma urealyticum clinical isolates from perinatal patients in Japan

Ureaplasma spp. cause several disorders, such as nongonococcal urethritis, miscarriage, and preterm delivery with lung infections in neonates, characterized by pathological chorioamnionitis in the placenta. Although reports on antibiotic resistance in Ureaplasma are on the rise, reports on quinolone-resistant Ureaplasma infections in Japan are limited. The purpose of this study was to determine susceptibilities to five quinolones of Ureaplasma urealyticum and Ureaplasma parvum isolated from perinatal samples in Japan and to characterize the quinolone resistance-determining regions in the gyrA, gyrB, parC, and parE genes. Out of 28 clinical Ureaplasma strains, we isolated 9 with high MICs of quinolones and found a single parC gene mutation, resulting in the change S83L. Among 158 samples, the ParC S83L mutation was found in 37 samples (23.4%), including 1 sample harboring a ParC S83L-GyrB P462S double mutant. Novel mutations of ureaplasmal ParC (S83W and S84P) were independently found in one of the samples. Homology modeling of the ParC S83W mutant suggested steric hindrance of the quinolone-binding pocket (QBP), and de novo prediction of peptide structures revealed that the ParC S84P may break/kink the formation of the α4 helix in the QBP. Further investigations are required to unravel the extent and mechanism of antibiotic resistance of Ureaplasma spp. in Japan.

16S rRNA gene mutations associated with decreased susceptibility to tetracycline in Mycoplasma bovis

Mycoplasma bovis isolates with decreased susceptibilities to tetracyclines are increasingly reported worldwide. The acquired molecular mechanisms associated with this phenomenon were investigated in 70 clinical isolates of M. bovis. Sequence analysis of the two 16S rRNA-encoding genes (rrs3 and rrs4 alleles) containing the primary binding pocket for tetracycline (Tet-1 site) was performed on isolates with tetracycline hydrochloride MICs of 0.125 to 16 μg/ml. Mutations at positions A965T, A967T/C (Escherichia coli numbering) of helix 31, U1199C of helix 34, and G1058A/C were identified. Decreased susceptibilities to tetracycline (MICs, ≥2 μg/ml) were associated with mutations present at two (A965 and A967) or three positions (A965, A967, and G1058) of the two rrs alleles. No tet(M), tet(O), or tet(L) determinants were found in the genome of any of the 70 M. bovis isolates. The data presented correlate (P<0.0001) the mutations identified in the Tet-1 site of clinical isolates of M. bovis with decreased susceptibility to tetracycline.

Detection of the tetM resistance determinant among phenotypically sensitive Ureaplasma species by a novel real-time PCR method

The study aimed to identify the proportion of tetM-positive Ureaplasma spp. isolates phenotypically susceptible to tetracycline by real-time PCR. Ureaplasma spp. strains of urogenital origin were isolated from 100 female or male adults on A7 agar plates. The presence of Ureaplasma was confirmed by the presence of urease gene by a novel real-time PCR method. Genotyping and sensitivity to tetracyclines were examined using commercial methods. The tetM gene was detected by a novel real-time PCR method especially designed for this study. Ureaplasma parvum was isolated from 87 of the specimens; Ureaplasma urealyticum, from 12; and both species were isolated from a single specimen. All isolates were phenotypically susceptible to tetracyclines. Thirty-five strains were tetM carriers; 29 (82.9%), U. parvum; 5 (14.3%), U. urealyticum; and 1 (2.9%), U. parvum/U. urealyticum. No statistically significant difference was observed between the 3 groups. Four (40%) tetM carriers were isolated from 10 symptomatic men; 11 (32.4%), from 34 symptomatic women; and 20 (35.7%), from 56 asymptomatic women. No statistically significant difference was observed between the 3 groups. The tetM determinant is detected in 35% of phenotypically susceptible to tetracycline Ureaplasma spp. Greek isolates. The use of a real-time PCR technique is particularly helpful, as it makes its detection easy; cost-effective; rapid; and, therefore, more convenient for the surveillance of the dissemination of the tetM resistance gene.

Random insertion and gene disruption via transposon mutagenesis of Ureaplasma parvum using a mini-transposon plasmid

While transposon mutagenesis has been successfully used for Mycoplasma spp. to disrupt and determine non-essential genes, previous attempts with Ureaplasma spp. have been unsuccessful. Using a polyethylene glycol-transformation enhancing protocol, we were able to transform three separate serovars of Ureaplasma parvum with a Tn4001-based mini-transposon plasmid containing a gentamicin resistance selection marker. Despite the large degree of homology between Ureaplasma parvum and Ureaplasma urealyticum, all attempts to transform the latter in parallel failed, with the exception of a single clinical U. urealyticum isolate. PCR probing and sequencing were used to confirm transposon insertion into the bacterial genome and identify disrupted genes. Transformation of prototype serovar 3 consistently resulted in transfer only of sequence between the mini-transposon inverted repeats, but some strains showed additional sequence transfer. Transposon insertion occurred randomly in the genome resulting in unique disruption of genes UU047, UU390, UU440, UU450, UU520, UU526, UU582 for single clones from a panel of screened clones. An intergenic insertion between genes UU187 and UU188 was also characterised. Two phenotypic alterations were observed in the mutated strains: Disruption of a DEAD-box RNA helicase (UU582) altered growth kinetics, while the U. urealyticum strain lost resistance to serum attack coincident with disruption of gene UUR10_137 and loss of expression of a 41 kDa protein. Transposon mutagenesis was used successfully to insert single copies of a mini-transposon into the genome and disrupt genes leading to phenotypic changes in Ureaplasma parvum strains. This method can now be used to deliver exogenous genes for expression and determine essential genes for Ureaplasma parvum replication in culture and experimental models.

Repeated maternal intramuscular or intraamniotic erythromycin incompletely resolves intrauterine Ureaplasma parvum infection in a sheep model of pregnancy

OBJECTIVE

Ureaplasma spp are the most commonly isolated microorganisms in association with preterm birth. Maternal erythromycin administration is a standard treatment for preterm prelabor rupture of membranes. There is little evidence of its effectiveness in eradicating Ureaplasma spp from the intrauterine cavity and fetus. We used a sheep model of intrauterine Ureaplasma spp infection to investigate the efficacy of repeated maternal intramuscular and intraamniotic erythromycin treatment to eradicate such an infection.

STUDY DESIGN

Thirty ewes with singleton pregnancies received an intraamniotic injection of 10(7) color change units of erythromycin-sensitive Ureaplasma parvum serovar 3 at 55 days' gestation. At 116 days' gestation, 28 ewes with viable fetuses were randomized to receive (1) intraamniotic and maternal intramuscular saline solution treatment (n = 8), (2) single intraamniotic and repeated maternal intramuscular erythromycin treatment (n = 10), or (3) single maternal intramuscular and repeated intraamniotic erythromycin treatment (n = 10). Fetuses were surgically delivered at 125 days' gestation. Treatment efficacy was assessed by culture, quantitative polymerase chain reaction, and histopathologic evaluation.

RESULTS

Animals treated with intraamniotic erythromycin had significantly less viable U parvum serovar 3 in the amniotic fluid at delivery. However, neither combination of maternal intramuscular and intraamniotic erythromycin treatment successfully cleared U parvum serovar 3 from the amniotic fluid or fetal tissues. Three de novo erythromycin-resistant U parvum isolates were identified in erythromycin-treated animals.

CONCLUSION

Erythromycin treatment, given both to the ewe and into the amniotic cavity, fails to eradicate intrauterine and fetal U parvum serovar 3 infection and may lead to development of erythromycin resistant U parvum.

Maternal intravenous treatment with either azithromycin or solithromycin clears Ureaplasma parvum from the amniotic fluid in an ovine model of intrauterine infection

Intrauterine infection with Ureaplasma spp. is strongly associated with preterm birth and adverse neonatal outcomes. We assessed whether combined intraamniotic (IA) and maternal intravenous (IV) treatment with one of two candidate antibiotics, azithromycin (AZ) or solithromycin (SOLI), would eradicate intrauterine Ureaplasma parvum infection in a sheep model of pregnancy. Sheep with singleton pregnancies received an IA injection of U. parvum serovar 3 at 85 days of gestational age (GA). At 120 days of GA, animals (n=5 to 8/group) received one of the following treatments: (i) maternal IV SOLI with a single IA injection of vehicle (IV SOLI only); (ii) maternal IV SOLI with a single IA injection of SOLI (IV+IA SOLI); (iii) maternal IV AZ and a single IA injection of vehicle (IV AZ only); (iv) maternal IV AZ and a single IA injection of AZ (IV+IA AZ); or (v) maternal IV and single IA injection of vehicle (control). Lambs were surgically delivered at 125 days of GA. Treatment efficacies were assessed by U. parvum culture, quantitative PCR, enzyme-linked immunosorbent assay, and histopathology. Amniotic fluid (AF) from all control animals contained culturable U. parvum. AF, lung, and chorioamnion from all AZ- or SOLI-treated animals (IV only or IV plus IA) were negative for culturable U. parvum. Relative to the results for the control, the levels of expression of interleukin 1β (IL-1β), IL-6, IL-8, and monocyte chemoattractant protein 2 (MCP-2) in fetal skin were significantly decreased in the IV SOLI-only group, the MCP-1 protein concentration in the amniotic fluid was significantly increased in the IV+IA SOLI group, and there was no significant difference in the histological inflammation scoring of lung or chorioamnion among the five groups. In the present study, treatment with either AZ or SOLI (IV only or IV+IA) effectively eradicated macrolide-sensitive U. parvum from the AF. There was no discernible difference in antibiotic therapy efficacy between IV-only and IV+IA treatment regimens relative to the results for the control.

Ureaplasma parvum undergoes selection in utero resulting in genetically diverse isolates colonizing the chorioamnion of fetal sheep

Ureaplasmas are the microorganisms most frequently isolated from the amniotic fluid of pregnant women and can cause chronic intrauterine infections. These tiny bacteria are thought to undergo rapid evolution and exhibit a hypermutatable phenotype; however, little is known about how ureaplasmas respond to selective pressures in utero. Using an ovine model of chronic intraamniotic infection, we investigated if exposure of ureaplasmas to subinhibitory concentrations of erythromycin could induce phenotypic or genetic indicators of macrolide resistance. At 55 days gestation, 12 pregnant ewes received an intraamniotic injection of a nonclonal, clinical Ureaplasma parvum strain followed by (i) erythromycin treatment (intramuscularly, 30 mg/kg/day, n = 6) or (ii) saline (intramuscularly, n = 6) at 100 days gestation. Fetuses were then delivered surgically at 125 days gestation. Despite injecting the same inoculum into all the ewes, significant differences between amniotic fluid and chorioamnion ureaplasmas were detected following chronic intraamniotic infection. Numerous polymorphisms were observed in domain V of the 23S rRNA gene of ureaplasmas isolated from the chorioamnion (but not the amniotic fluid), resulting in a mosaiclike sequence. Chorioamnion isolates also harbored the macrolide resistance genes erm(B) and msr(D) and were associated with variable roxithromycin minimum inhibitory concentrations. Remarkably, this variability occurred independently of exposure of ureaplasmas to erythromycin, suggesting that low-level erythromycin exposure does not induce ureaplasmal macrolide resistance in utero. Rather, the significant differences observed between amniotic fluid and chorioamnion ureaplasmas suggest that different anatomical sites may select for ureaplasma subtypes within nonclonal, clinical strains. This may have implications for the treatment of intrauterine ureaplasma infections.

Prevalence and antimicrobial susceptibility of Ureaplasma urealyticum in asymptomatic women in Northern Greece

AIM

This study attends to determine the prevalence and the antimicrobial susceptibility of Ureaplasma urealyticum in asymptomatic women in Northern Greece.

MATERIALS-METHODS

A total of 347 cervical smears were divided into 5 groups according to age. Samples were cultured, Ureaplasma urealyticum isolation was confirmed by the detection of the urease gene and the antimicrobial susceptibility of the isolates to 9 commercially available antibiotics was determined.

RESULTS

Fifty-six (16.13%) samples were found positive. Women >60 years old were rarely infected. Only 9 (16.07%) isolates were susceptible to all antimicrobials tested. Thirteen isolates were resistant and 34 intermediately resistant to ciprofloxacin, two resistant and 29 intermediately resistant to ofloxacin, three intermediately resistant to macrolides, while all were susceptible to tetracyclines.

CONCLUSIONS

In Northern Greece, 16.13% of asymptomatic women seem to be carriers of Ureaplasma urealyticum mostly in reproductive ages. Almost no resistance to macrolides and tetracyclines has been noticed, while most of the isolates present resistance or moderate sensitivity to quinolones.

Comparison of the new Mycofast Revolution assay with a molecular assay for the detection of genital mycoplasmas from clinical specimens

BACKGROUND

Genital mycoplasmas are opportunistic bacteria that are associated with undesirable gynaecologic and reproductive events. Mycoplasmas are fastidious bacteria with increasing resistance to routine antimicrobials and often fail to grow on conventional culture methods. The commercial Mycofast Revolution assay permits the phenotypic detection and identification of genital mycoplasmas. Antimicrobial susceptibility testing against five antimicrobial agents with MICs corresponding to the CLSI guidelines can also be performed. This study aimed to compare the new commercially available Mycofast Revolution assay with a multiplex PCR assay.

METHODS

Self-collected swabs were obtained from pregnant women attending the antenatal clinic of a tertiary academic hospital in Pretoria, South Africa from October 2012 to November 2012. These swabs were used to seed UMMt and modified Amies transport media. The seeded UMMt transported medium was used to inoculate the Mycofast Revolution assay for the identification, enumeration and antimicrobial susceptibility testing of genital mycoplasmas. Following DNA extraction from the modified Amies transport medium, specimens were subjected to a multiplex PCR assay for the detection of genital mycoplasmas.

RESULTS

The Mycofast Revolution kit had a sensitivity and specificity of 77.3% (95% CI: 62.15% to 88.51%) and 80% (95% CI: 28.81% to 96.70%), respectively, against the PCR assay. The positive and negative predictive values were 97.1% (95% CI: 85.03% to 99.52%) and 28.6% (95% CI: 8.57% to 58.08%). Genital mycoplasmas were detected in 71.4% (35/49) of samples with the Mycofast Revolution assay with 49% (24/49) being Ureaplasma spp. and 22.4% (11/49) mixed strains. The multiplex PCR assay had a positivity rate of 89.8% (44/49) for genital mycoplasmas; mixed strains were present in 51% (25/49) of samples, Ureaplasma spp. in 16.3% (8/49) and M. hominis in 22.4% (11/49) of samples.

CONCLUSIONS

There was a fair agreement (κ = 0.319) between the Mycofast Revolution assay and the mPCR assay. With the high prevalence rates of genital mycoplasmas, fast and efficient diagnostic methods are imperative to treat infections and minimise complications. The Mycofast Revolution assay is simple to use, has a short turn-around time and interpretation of results are straightforward. This assay circumvents common problems experienced with conventional culture and molecular methods in diagnostic laboratories where skilled personnel are limited and can be used as an alternative diagnostic assay.

Appropriate antibiotic therapy improves Ureaplasma sepsis outcome in the neonatal mouse

BACKGROUND

Ureaplasma causes sepsis in human neonates. Although erythromycin has been the standard treatment, it is not always effective. No published reports have evaluated Ureaplasma sepsis in a neonatal model. We hypothesized that appropriate antibiotic treatment improves Ureaplasma sepsis in a neonatal mouse model.

METHODS

Two ATCC strains and two clinical strains of Ureaplasma were evaluated in vitro for antibiotic minimum inhibitory concentration (MIC). In addition, FVB albino mice pups infected with Ureaplasma were randomly assigned to saline, erythromycin, or azithromycin therapy and survival, quantitative blood culture, and growth were evaluated.

RESULTS

MICs ranged from 0.125 to 62.5 µg/ml and 0.25 to 1.0 µg/ml for erythromycin and azithromycin, respectively. The infecting strain and antibiotic selected for treatment appeared to affect survival and bacteremia, but only the infecting strain affected growth. Azithromycin improved survival and bacteremia against each strain, whereas erythromycin was effective against only one of four strains.

CONCLUSION

We have established a neonatal model of Ureaplasma sepsis and observed that treatment outcome is related to infecting strain and antibiotic treatment. We speculate that appropriate antibiotic selection and dosing are required for effective treatment of Ureaplasma sepsis in neonates, and this model could be used to further evaluate these relationships.

Antibiotic susceptibilities and resistance genes of Ureaplasma parvum isolated in South Africa

OBJECTIVES

There is only limited information on the antimicrobial susceptibilities and resistance genes of Ureaplasma parvum in South Africa. This study was designed to detect and characterize resistance genes in U. parvum.

METHODS

Fifteen U. parvum isolates were investigated employing the broth microdilution method (tetracycline, doxycycline, ofloxacin, erythromycin, azithromycin and josamycin). Gene analyses were performed on target regions of: tet(M); gyrA, gyrB, parC and parE; erm(A), erm(B), erm(C) and erm(E); msr(A), msr(B), msr(C) and msr(D); 23S rRNA operons; and L4 and L22 ribosomal proteins.

RESULTS

Seven of the U. parvum isolates were fully susceptible to the antibiotics tested. Five strains exhibited resistance to tetracycline (MICs 16-256 mg/L), one strain was resistant to ofloxacin (MIC 128 mg/L) and four strains were resistant to macrolides (MICs 128 mg/L); two strains showed dual resistance to tetracycline and erythromycin. The five tetracycline-resistant strains were found to have mosaic tet(M) genes, with one strain containing different specific regions to those previously described. Mutations in the L22 ribosomal protein were seen in three strains that were resistant to erythromycin (two strains) and erythromycin + azithromycin (one strain). For a further strain that was resistant to erythromycin and azithromycin, possible mechanisms of resistance remained elusive.

CONCLUSIONS

This is the first report of quinolone, erythromycin and azithromycin resistance development in U. parvum from South Africa. A point mutation in parC (Pro-57 → Leu) and two novel mutations in parE (Ile-73 → Thr and a methionine insertion at codon 86) were found in an ofloxacin-resistant strain. The study reinforces the adaptability of U. parvum to develop resistance and acquire, modify and maintain transposon-located resistance genes.