Genetic basis of natural resistance to erythromycin in Mycoplasma hominis

The complete genome sequence of unculturable Mycoplasma faucium obtained through clinical metagenomic next-generation sequencing

Introduction

Diagnosing Mycoplasma faucium poses challenges, and it's unclear if its rare isolation is due to infrequent occurrence or its fastidious nutritional requirements.

Methods

This study analyzes the complete genome sequence of M. faucium, obtained directly from the pus of a sternum infection in a lung transplant patient using metagenomic sequencing.

Results

Genome analysis revealed limited therapeutic options for the M. faucium infection, primarily susceptibility to tetracyclines. Three classes of mobile genetic elements were identified: two new insertion sequences, a new prophage (phiUMCG-1), and a species-specific variant of a mycoplasma integrative and conjugative element (MICE). Additionally, a Type I Restriction-Modification system was identified, featuring 5'-terminally truncated hsdS pseudogenes with overlapping repeats, indicating the potential for forming alternative hsdS variants through recombination.

Conclusion

This study represents the first-ever acquisition of a complete circularized bacterial genome directly from a patient sample obtained from invasive infection of a primary sterile site using culture-independent, PCR-free clinical metagenomics.

Trends of fluoroquinolones resistance in Mycoplasma and Ureaplasma urogenital isolates: Systematic review and meta-analysis

BACKGROUND

Mycoplasma and Ureaplasma spp. especially M. hominis, U. parvum, and U. urealyticum recognized as an important cause of urogenital infections. Sake of the presence of antibiotic resistance and a continuous rise in resistance, the treatment options are limited, and treatment has become more challenging and costlier.

OBJECTIVES

Therefore, this meta-analysis aimed to estimate worldwide resistance rates of genital Mycoplasmas and Ureaplasma to fluoroquinolones (ciprofloxacin, ofloxacin, moxifloxacin, and levofloxacin) agents.

METHODS

We searched the relevant published studies in PubMed, Scopus, and Embase from until 3, March 2022. All statistical analyses were carried out using the statistical package R.

RESULTS

The 30 studies included in the analysis were performed in 16 countries. In the metadata, the proportions of ciprofloxacin, ofloxacin, moxifloxacin, and levofloxacin resistance in Mycoplasma and Ureaplasma urogenital isolates were reported 59.8% (95% CI 49.6, 69.1), 31.2% (95% CI 23, 40), 7.3% (95% CI 1, 31), and 5.3% (95% CI 1, 2), respectively. According to the meta-regression, the ciprofloxacin, ofloxacin, moxifloxacin, and levofloxacin rate increased over time. There was a statistically significant difference in the fluoroquinolones resistance rates between different continents/countries (P < 0.05).

CONCLUSIONS

Based on the results obtained in this systematic review and meta-analysis we recommend the use of the newer group of fluoroquinolones especially levofloxacin as the first choice for the treatment of genital mycoplasmosis, as well as ofloxacin for the treatment of genital infections caused by U. parvum.

Tetracyclines resistance in Mycoplasma and Ureaplasma urogenital isolates derived from human: a systematic review and meta-analysis

BACKGROUND

Urogenital Mycoplasma infections are considered an important public health problem, owing to the presence of antibiotic resistance or decreased susceptibility, the treatment options are limited.

OBJECTIVE

Therefore, this meta-analysis aimed to estimate resistance rates of genital Mycoplasmas to tetracyclines (tetracycline, doxycycline, and minocycline).

METHODS

We searched the relevant published studies in PubMed, Scopus, and Embase until 3, March 2022. All statistical analyses were carried out using the statistical package R.

RESULTS

The 26 studies included in the analysis were performed in 15 countries. In the metadata, the proportions of tetracycline, doxycycline, and minocycline resistance in Mycoplasma and Ureaplasma urogenital isolates were reported 14.2% (95% CI 8.2-23.2%), 5% (95% CI 3-8.1%), and 11.9% (95% CI 6.3-21.5%), respectively. According to the meta-regression, the tetracycline and minocycline resistance rate decreased over time. Although, the doxycycline resistance rate increased over time. There was a statistically significant difference in the tetracyclines resistance rates between different continents/countries (P < 0.05).

CONCLUSION

The prevalence rate and antibiotic susceptibility profiles vary geographically. Therefore, rigorous or improved antimicrobial stewardship, contact tracing, and enhanced intensive surveillance systems are necessitated for preventing the emergence and further spreading of tetracyclines resistance in genital Mycoplasmas.

Retrospective Analysis of Azithromycin-Resistant Ureaplasma urealyticum and Mycoplasma hominis Cervical Infection Among Pregnant Women

Purpose

Ureaplasma urealyticum and Mycoplasma hominis began to show resistance to azithromycin, a macrolide antibiotic commonly used in pregnancy. Unfortunately, there are few effective and safe drugs in the clinic for genital mycoplasmas in pregnant women. In the present study, we investigated the prevalence of azithromycin-resistant U. urealyticum and M. hominis infections in pregnant women. The secondary research objects were possible influencing factors and consequences of insensitive Mycoplasma infection.

Patients and methods

A retrospective analysis was carried out in pregnant women who underwent cervical Mycoplasma culture between October 2020 and October 2021 at a large general hospital in eastern China. The sociological characteristics and clinical information of these women were collected and analyzed.

Results

A total of 375 pregnant women were enrolled, and 402 cultured mycoplasma specimens were collected. Overall, 186 (49.60%) patients tested positive cervical Mycoplasma infection, and 37 (9.87%) had infections caused by azithromycin-resistant Mycoplasma. In total, 39 mycoplasma samples were insensitive to azithromycin in vitro, also showing extremely high resistance to erythromycin, roxithromycin, and clarithromycin. Azithromycin was the only antibiotic used in women with Mycoplasma cervical infection, regardless of azithromycin resistance in vitro. Statistical results showed that azithromycin-resistant cervical Mycoplasma infection in pregnant women was unrelated to age, body mass index (BMI), gestational age, number of embryos, and assisted reproductive technology (ART) use, but led to a significantly increased incidence of adverse pregnancy outcomes (spontaneous abortion (SA), preterm birth (PTB), preterm prelabor rupture of membranes (PPROM), and stillbirth).

Conclusion

Azithromycin-resistant U. urealyticum and M. hominis cervical infections are relatively common during pregnancy, and can increase the risk of adverse pregnancy outcomes; however, there is currently a lack of safe and effective drug treatments. Herein, we show that azithromycin-resistant mycoplasma infection requires timely intervention.

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.

Epidemiological investigation and antimicrobial susceptibility analysis of Ureaplasma and Mycoplasma hominis in a teaching hospital in Shenyang, China

OBJECTIVES

The aim of this study was to estimate the prevalence and antimicrobial susceptibility of Ureaplasma urealyticum and Mycoplasma hominis in a comprehensive teaching hospital Shenyang, China over the past 4 years.

METHODS

A total of 1448 individuals with urogenital symptoms underwent mycoplasma testing between April 2016 and March 2020. Detection, identification and antimicrobial susceptibility testing were carried out using Mycoplasma ID/AST kits.

RESULTS

The total infection rate of genital mycoplasmas was 37.5% (543/1448 cases) with an observed increase over the past 4 years. The positive rates of all three detected infections, as well as overall infection rate, were significantly higher in females than in males (P < 0.05). A higher positive rate of infection was observed in females aged 25-29 (60.5%), and in the 15-19 years age group (57.7%). The changes observed among all age groups of females were statistically significantly different (P < 0.001). The positive rates of U. urealyticum and M. hominis co-infection among the four seasons during which the survey was carried out were also observed to be statistically different (P = 0.01). More than 70% of U. urealyticum isolates were found to be resistant to ciprofloxacin, and more than 80% of M. hominis isolates were resistant to erythromycin, roxithromycin, azithromycin and clarithromycin. Josamycin, doxycycline and minocycline were most effective against U. urealyticum and M. hominis.

CONCLUSIONS

Results of this study found increasing rates of U. urealyticum and M. hominis infection over the past 4 years, particularly among younger age groups. U. urealyticum/Mycoplasma hominis screening among younger age cohorts are therefore strongly recommend to preventing the spread of pathogens. Monitoring antimicrobial resistance is important for preventing transmission of resistant strains of infection and for the management of antibiotics.

Prevalence and antimicrobial susceptibility of Ureaplasma species and Mycoplasma hominis in Greek female outpatients, 2012-2016

Mycoplasma hominis and Ureaplasma species are opportunistic pathogens associated with urogenital infections, complications during pregnancy and postpartum infections. Appropriate empirical antimicrobial treatment is necessary to achieve an optimal therapeutic outcome. This study evaluated the prevalence and the antimicrobial susceptibility of Mycoplasma hominis and Ureaplasma spp. isolated from 1,008 endocervical samples of outpatients in Crete, Greece, during a five-year period (2012-2016), using the commercially available Mycoview kit (Zeakon diagnostics, France). Ureaplasma spp. was isolated from 116 patients (11.5%), M. hominis from 6 (0.6%), while coinfection with both mycoplasmas was demonstrated in 17 (1.7%). All Ureaplasma strains were susceptible to josamycin and doxycycline. Doxycycline, minocycline and ofloxacin were the most potent antibiotics against M. hominis. Docycycline was proved the most active and is still the drug of choice for the treatment of genital mycoplasma infections. Local surveillance to monitor changes in antimicrobial susceptibilities is necessary to guide treatment strategies.

Cardiothoracic Transplant Recipient Mycoplasma hominis: An Uncommon Infection with Probable Donor Transmission

The role of infection with Mycoplasma hominis following cardiothoracic organ transplantation and its source of transmission have not been well-defined. Here, we identify and describe infection with M. hominis in patients following cardiothoracic organ transplantation after reviewing all cardiothoracic transplantations performed at our center between 1998 and July 2015. We found seven previously unreported cases of M. hominis culture positive infection all of whom presented with pleuritis, surgical site infection, and/or mediastinitis. PCR was used to establish the diagnosis in four cases. In two instances, paired single lung transplant recipients manifested infection, and in one of these pairs, isolates were indistinguishable by multilocus sequence typing (MLST). To investigate the prevalence of M. hominis in the lower respiratory tract, we tested 178 bronchoalveolar lavage (BAL) fluids collected from immunocompromised subjects for M. hominis by PCR; all were negative. Review of the literature revealed an additional 15 cases of M. hominis in lung transplant recipients, most with similar clinical presentations to our cases. We recommend that M. hominis should be considered in post-cardiothoracic transplant infections presenting with pleuritis, surgical site infection, or mediastinitis. M. hominis PCR may facilitate early diagnosis and prompt therapy. Evaluation for possible donor transmission should be considered.

Comparative analysis of male and female populations on prevalence and antibiotic resistance of Mycoplasma hominis in China, 2005-2014

The aim of this study was to estimate the prevalence and antimicrobial resistance rate of Mycoplasma hominis among male and female populations. A total of 67921 individuals were examined. All samples were isolated from patients at an outpatient clinic from January 2005 to December 2014. Species identification and antibiotic susceptibility testing were performed using Mycoplasma IST2. In this study, 523 (0.8%) and 4625 (6.8%) cultures, respectively, were positive for single M. hominis identification and simultaneous identification of both M. hominis and Ureaplasma spp. The results showed that both single and simultaneous identification were more frequent in the female than the male population. Moreover, the highest positive rates of single M. hominis identification were observed in 56-60-year-old males and 61-65-year-old females, and the rates of simultaneous identification were high in males aged >65 years and females aged 15-20 years. Among the seven antibiotics assessed, tetracycline, josamycin, doxycycline and pristinamycin were the most effective, whilst clarithromycin, ciprofloxacin and ofloxacin displayed extremely high resistance rates. Different antimicrobial susceptibility rates were observed between the two sexes, and the resistance rates to ofloxacin showed a significant difference (P<0.05). In conclusion, this study demonstrates that the prevalence of M. hominis varied significantly between the two sexes in the past 10 years and that the optimal antimicrobial therapy strategy should be directed by local susceptibility testing.

A case of septic arthritis caused by a Mycoplasma salivarium strain resistant towards Ciprofloxacin and Clarithromycin in a patient with chronic lymphatic leukemia

Mycoplasma salivarium is a rare agent of septic arthritis in immunocompromised patients. We report a case of septic arthritis due to Mycoplasma salivarium in a patient with B-cell chronic lymphocytic leukemia who underwent chemotherapy with rituximab and bendamustin. Therapy of arthritis due to Mycoplasma salivarium is difficult because there are almost no susceptibility data available. The present case illustrates that antimicrobial susceptibility of Mycoplasma strains is not necessarily predictable and that antibiotic therapy should therefore be guided by in vitro susceptibility testing.

In vitro susceptibility of Mycoplasma hyopneumoniae field isolates and occurrence of fluoroquinolone, macrolides and lincomycin resistance

A total of 159 Thai isolates of Mycoplasma hyopneumoniae isolated from pneumonic lungs of pigs during 2006-2011 were investigated for their in vitro susceptibility to 12 antimicrobial agents. Low activity of chlortetracycline was indicated by the MIC range from 3.12-100 μg/ml and MIC90 of 50 μg/ml. Seventy-six isolates showed resistance to enrofloxacin, whereas 2 isolates showed resistance to macrolides and lincomycin. In addition, a point mutation at A2058G was revealed by sequence analysis of 23S ribosomal RNA in both isolates. The present results confirmed the rapid increase of resistant M. hyopneumoniae isolates against chlortetracycline, enrofloxacin, macrolides and lincomycin in Thailand. Selection of drugs to control swine diseases in Thailand must be done more prudently in consideration of reducing the antimicrobial resistance.

In vitro susceptibilities of Mycoplasma putrefaciens field isolates

MICs were determined for 15 antimicrobial agents against 37 Mycoplasma putrefaciens isolates. The most effective antimicrobial drug classes were the fluoroquinolones, the tetracyclines, the lincosamide lincomycin, and the macrolides. The susceptibility profile of the isolates correlated with the geographic origin. This is the first report of decreased susceptibility to the macrolides, lincomycin, and the tetracyclines in M. putrefaciens strains.

Responses of wild-type and resistant strains of the hyperthermophilic bacterium Thermotoga maritima to chloramphenicol challenge

Transcriptomes and growth physiologies of the hyperthermophile Thermotoga maritima and an antibiotic-resistant spontaneous mutant were compared prior to and following exposure to chloramphenicol. While the wild-type response was similar to that of mesophilic bacteria, reduced susceptibility of the mutant was attributed to five mutations in 23S rRNA and phenotypic preconditioning to chloramphenicol.

Mycoplasmas and ureaplasmas as neonatal pathogens

The genital mycoplasmas represent a complex and unique group of microorganisms that have been associated with a wide array of infectious diseases in adults and infants. The lack of conclusive knowledge regarding the pathogenic potential of Mycoplasma and Ureaplasma spp. in many conditions is due to a general unfamiliarity of physicians and microbiology laboratories with their fastidious growth requirements, leading to difficulty in their detection; their high prevalence in healthy persons; the poor design of research studies attempting to base association with disease on the mere presence of the organisms in the lower urogenital tract; the failure to consider multifactorial aspects of diseases; and considering these genital mycoplasmas only as a last resort. The situation is now changing because of a greater appreciation of the genital mycoplasmas as perinatal pathogens and improvements in laboratory detection, particularly with regard to the development of powerful molecular nucleic acid amplification tests. This review summarizes the epidemiology of genital mycoplasmas as causes of neonatal infections and premature birth; evidence linking ureaplasmas with bronchopulmonary dysplasia; recent changes in the taxonomy of the genus Ureaplasma; the neonatal host response to mycoplasma and ureaplasma infections; advances in laboratory detection, including molecular methods; and therapeutic considerations for treatment of systemic diseases.

Characterization of In Vivo Acquired Resistance of Mycoplasma hyopneumoniae to Macrolides and Lincosamides

Macrolides and related antibiotics are used to control mycoplasma infections in the pig industry worldwide. Some porcine mycoplasmas, however, survive these treatments by acquiring resistance. The mechanism of acquired resistance to macrolides and lincosamides was studied in more detail for Mycoplasma hyopneumoniae by comparing both the phenotype and genotype of a resistant field isolate to five susceptible isolates. The MICs were significantly higher for the resistant strain for all antibiotics tested. The MICs for the 16-membered macrolide tylosin ranged from 8 to 16 microg for the resistant strain and from 0.03 to 0.125 microg/ml for the five susceptible strains. The MICs for the 15-membered macrolides and lincosamides were higher than 64 microg/ml for the resistant strain while only 0.06 to 0.5 microg/ml for the susceptible strains. Mycoplasma hyopneumoniae strains are intrinsically resistant to the 14-membered macrolides due to a G 2057 A transition (E. coli numbering) in their 23S rDNA. Therefore, high MICs were observed for all strains, although the MICs for the resistant strain were clearly increased. An additional, acquired A 2058 G point mutation was found in the 23S rRNA gene of the resistant strain. No differences linked to resistance were found in the ribosomal proteins L4 and L22. The present study showed that 23S rRNA mutations resulting in resistance to macrolides and lincosamides as described in other Mycoplasma spp. also occur under field conditions in M. hyopneumoniae.

The vlhA loci of Mycoplasma synoviae are confined to a restricted region of the genome

Mycoplasma synoviae, a major pathogen of poultry, contains a single expressed, full-length vlhA gene encoding its haemagglutinin, and a large number of vlhA pseudogenes that can be recruited by multiple site-specific recombination events to generate chimaeric variants of the expressed gene. The position and distribution of the vlhA pseudogene regions, and their relationship with the expressed gene, have not been investigated. To determine the relationship between these regions, a physical map of the M. synoviae genome was constructed using the restriction endonucleases SmaI, I-CeuI, BsiWI, ApaI and XhoI and radiolabelled probes for rrnA, recA and tufA. A cloned fragment encoding the unique portion of the expressed vlhA gene and two PCR products containing conserved regions of the ORF 3 and ORF 6 vlhA pseudogenes were used to locate the regions containing these genes on the map. The chromosome of M. synoviae was found to be 890·4 kb and the two rRNA operons were in the same orientation. Both the expressed vlhA gene and the vlhA pseudogenes were confined to the same 114 kb region of the chromosome. These findings indicate that, unlike Mycoplasma gallisepticum, in which the vlhA genes are located in several loci around the chromosome and in which antigenic variation is generated by alternating transcription of over 40 translationally competent genes, M. synoviae has all of the vlhA sequences clustered together, suggesting that close proximity is needed to facilitate the site-specific recombinations used to generate diversity in the expressed vlhA gene.

In vitro activities of ABT-773 and other antimicrobials against human mycoplasmas

The in vitro susceptibilities of 103 Mycoplasma pneumoniae isolates, 14 Mycoplasma hominis isolates, 12 Mycoplasma fermentans isolates, and 24 Ureaplasma species to ABT-773, an investigational ketolide, and seven other agents were determined. For M. pneumoniae, the ABT-773 MIC at which 90% of isolates are inhibited (MIC(90); <or=0.001 microg/ml) was comparable to those of azithromycin, clarithromycin, and erythromycin and at least 128-fold lower than those of levofloxacin, gatifloxacin, moxifloxacin, and doxycycline. For M. fermentans, the ABT-773 MIC(90) (<or=0.008 microg/ml) was 2- to 128-fold lower than those of all other agents tested. For M. hominis, the ABT-773 MIC(90) (0.031 microg/ml) was equivalent to that of moxifloxacin, 2-fold lower than those of gatifloxacin and clindamycin, and 16-fold lower than that of levofloxacin. ABT-773 was equally active against doxycycline-susceptible and doxycycline-resistant organisms. The ABT-773 MICs (0.016 microg/ml) for Ureaplasma species were the lowest of those of any drug tested. The MIC(90) was 4- to 64-fold lower than those of clarithromycin, azithromycin, and erythromycin and >or=16-fold lower than those of all three fluoroquinolones. Minimal bactericidal concentrations determined for a subgroup of organisms were <or=0.063 micro g/ml for M. pneumoniae and 0.25 microg/ml for M. fermentans, but they were several dilutions higher for M. hominis and Ureaplasma spp. ABT-773 has great potential for further study for the treatment of infections due to mycoplasmas and ureaplasmas.

Mutations in 23S rRNA account for intrinsic resistance to macrolides in Mycoplasma hominis and Mycoplasma fermentans and for acquired resistance to macrolides in M. hominis

The mechanisms of intrinsic resistance of Mycoplasma hominis to 14- and 15-membered macrolides were investigated in comparison with those of M. pneumoniae, which is naturally susceptible to macrolides. Radiolabeled erythromycin was not accumulated by M. hominis PG21, but addition of an ABC transporter inhibitor increased the level of erythromycin uptake more than two times, suggesting the existence of an active efflux process. The affinity of [(14)C]erythromycin to ribosomes isolated from M. hominis was dramatically reduced relative to that to ribosomes isolated from M. pneumoniae. The nucleotide sequences of 23S rRNA of both ribosomal operons rrnA and rrnB and ribosomal proteins L4 and L22 of M. hominis were obtained. Compared to the sequence of M. pneumoniae, M. hominis harbored a G2057A transition in its 23S rRNA sequence, as did M. fermentans, another mycoplasma that is erythromycin resistant. An additional C2610U change was also found in the sequence of M. hominis. Moreover, two M. hominis clinical isolates with acquired resistance to 16-membered macrolides were examined for mutations in domain II and domain V of 23S rRNA and in ribosomal proteins L4 and L22. Compared to the sequence of reference strain PG21, one isolate harbored a A2059G transition and a C2611U transition in one of the two rrn operons, while the other one was mutated only at position 2059, also on the same operon. No mutation was found in the two ribosomal protein sequences. Overall, the present study is an exhaustive characterization of the intrinsic resistance of M. hominis to 14- and 15-membered macrolides and the first description of mycoplasma clinical isolates resistant to macrolide, lincosamide, and streptogramin antibiotics harboring a mutation at position 2611 in the 23S rRNA.

In vitro development of resistance to enrofloxacin, erythromycin, tylosin, tiamulin and oxytetracycline in Mycoplasma gallisepticum, Mycoplasma iowae and Mycoplasma synoviae

The in vitro emergence of resistance to enrofloxacin, erythromycin, tylosin, tiamulin, and oxytetracycline in three avian Mycoplasma species, Mycoplasma gallisepticum, Mycoplasma synoviae and Mycoplasma iowae was studied. Mutants were selected stepwise and their MICs were determined after 10 passages in subinhibitory concentrations of antibiotic. High-level resistance to erythromycin and tylosin developed within 2-6 passages in the three Mycoplasma species. Resistance to enrofloxacin developed more gradually. No resistance to tiamulin or oxytetracycline could be evidenced in M. gallisepticum or M. synoviae after 10 passages whereas, resistant mutants were obtained with M. iowae. Cross-sensitivity tests performed on mutants demonstrated that mycoplasmas made resistant to tylosin were also resistant to erythromycin, whereas mutants made resistant to erythromycin were not always resistant to tylosin. Some M. iowae tiamulin-resistant mutants were also resistant to both macrolide antibiotics. Enrofloxacin and oxytetracycline did not induce any cross-resistance to the other antibiotics tested. These results show that Mycoplasma resistance to macrolides can be quickly selected in vitro, and thus, providing that similar results could be obtained under field conditions, that development of resistance to these antibiotics in vivo might also be a relatively frequent event.

Two new point mutations at A2062 associated with resistance to 16-membered macrolide antibiotics in mutant strains of Mycoplasma hominis

We describe two mutants of Mycoplasma hominis PG-21 which show resistance to 16-membered macrolides but susceptibility to lincosamides, obtained by in vitro exposure to increasing doses of josamycin. The 23S rRNA gene showed that each had a mutation (A2062G and A2062T) corresponding to nucleotide 2062 in Escherichia coli, which was associated with the acquired phenotype.