Latest Advances in Laboratory Detection of Mycoplasma genitalium.

Mycoplasma genitalium is an important sexually transmitted pathogen affecting both men and women. Its extremely slow growth in vitro and very demanding culture requirements necessitate the use of molecular-based diagnostic tests for its detection in clinical specimens. The recent availability of U.S. Food and Drug Administration (FDA)-cleared commercial molecular-based assays has enabled diagnostic testing to become more widely available in the United States and no longer limited to specialized reference laboratories. Advances in the knowledge of the epidemiology and clinical significance of M. genitalium as a human pathogen made possible by the availability of molecular-based testing have led to updated guidelines for diagnostic testing and treatment that have been published in various countries. This review summarizes the importance of M. genitalium as an agent of human disease, explains the necessity of obtaining a microbiological diagnosis, describes currently available diagnostic methods, and discusses how the emergence of antimicrobial resistance has complicated treatment alternatives and influenced the development of diagnostic tests for resistance detection, with an emphasis on developments over the past few years.

Omadacycline Is Highly Active In Vitro against Mycoplasma genitalium.

Here, we performed in vitro susceptibility testing on 10 Mycoplasma genitalium isolates against omadacycline, minocycline, tetracycline, doxycycline, moxifloxacin, levofloxacin, and azithromycin. Omadacycline was the most potent agent, with all MICs of ≤0.5 µg/mL. MICs were not affected by resistance to other agents, including resistance to other tetracycline class drugs. Omadacycline may be a potential treatment option for M. genitalium infection. IMPORTANCE There are very few clinical isolates of Mycoplasma genitalium available for in vitro susceptibility testing. We studied 10 isolates and determined that the new semisynthetic aminomethylcycline omadacycline is active against isolates that are resistant to tetracyclines, macrolides, and quinolones. These data suggest that clinical studies should be performed in order to see if omadacycline may be useful to treat urogenital infections caused by M. genitalium.

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.

Septic polyarthritis with Mycoplasma salivarium in a patient with common variable immunodeficiency: case report and review of the literature.

Mycoplasma salivarium is a common mycoplasma usually isolated from human oropharynx, particularly from individuals with periodontal disease. It is also among the more common mycoplasmal contaminants of eukaryotic cell cultures. Although M. salivarium has been isolated occasionally from abscesses and other sterile sites, to our knowledge, only three cases of septic arthritis have been documented in the past due to this organism, all in patients with humoral immunodeficiency. We now report a fourth case of septic polyarthritis in a patient with profound hypoimmunoglobulinemia who had experienced dental abscesses within the preceding 2 years. Our case highlights the importance of considering invasive mycoplasmal infection in hypogammaglobulinemic patients. It is likely of significance that the patient had suffered recurrent dental abscesses as a source of infection with M. salivarium .

In Vitro Activities of Eravacycline and Other Antimicrobial Agents against Human Mycoplasmas and Ureaplasmas.

We performed in vitro susceptibility testing for eravacycline in comparison to 4 other antimicrobials against 10 Mycoplasma genitalium, 40 Mycoplasma hominis, 44 Mycoplasma pneumoniae, 20 Ureaplasma parvum, and 20 Ureaplasma urealyticum isolates. All eravacycline MICs were ≤0.25 µg/ml, except that for one isolate of M. genitalium, for which the MIC was 2 µg/ml. Eravacycline was markedly more potent than tetracycline, azithromycin, moxifloxacin, and clindamycin against all isolates tested, which included 37 macrolide, tetracycline, and/or fluoroquinolone-resistant organisms.

Macrolide-resistant Mycoplasma pneumoniae pneumonia in transplantation: Increasingly typical?

Mycoplasma pneumoniae is one of the most common bacterial causes of pneumonia. Macrolide-resistant M pneumoniae (MRMP) was documented in 7.5% of isolates in the United States. Resistance portends poor outcomes to macrolide therapy, yet patients respond well to fluoroquinolones or tetracyclines such as minocycline. However, MRMP may be under-appreciated because M pneumoniae generally causes relatively mild infections in non-immunosuppressed adults that may resolve without effective therapy and because microbiological confirmation and susceptibility are not routinely performed. We report two cases of pneumonia due to MRMP in kidney transplant recipients. Both patients required hospital admission, worsened on macrolide therapy, and rapidly defervesced on doxycycline or levofloxacin. In one case, M pneumoniae was only identified by multiplex respiratory pathogen panel analysis of BAL fluid. Macrolide resistance was confirmed in both cases by real-time PCR and point mutations associated with macrolide resistance were identified. M pneumoniae was isolated from both cases, and molecular genotyping revealed the same genotype. In conclusion, clinicians should be aware of the potential for macrolide resistance in M pneumoniae, and may consider non-macrolide-based therapy for confirmed or non-responding infections in patients who are immunocompromised or hospitalized.

Evaluation of Commercial Molecular Diagnostic Methods for Detection and Determination of Macrolide Resistance in Mycoplasma pneumoniae.

We evaluated six commercial molecular tests targeting Mycoplasma pneumoniae, namely, the BioFire FilmArray respiratory panel (RP), the Meridian Alethia Mycoplasma Direct, the GenMark ePlex respiratory pathogen panel (RPP), the Luminex NxTAG RPP, the ELITech ELITe InGenius Mycoplasma MGB research use only (RUO) PCR, and the SpeeDx Resistance Plus MP assays. Laboratory-developed PCR assays at the University of Alabama at Birmingham and the Centers for Disease Control and Prevention were used as reference standards. Among 428 specimens, 212 were designated confirmed positives for M. pneumoniae The highest clinical sensitivities were found with the InGenius PCR (99.5%) and the FilmArray RP (98.1%). The Resistance Plus MP identified 93.3% of the confirmed-positive specimens, whereas 83.6, 64.6, and 55.7% were identified by the ePlex RPP, NxTAG RPP, and Mycoplasma Direct assays, respectively. There was no significant difference between the sensitivity of the reference methods and that of the FilmArray RP and InGenius assays, but the remaining four assays detected significantly fewer positive specimens (P < 0.05). Specificities of all assays were 99.5 to 100%. The Resistance Plus MP assay detected macrolide resistance in 27/33 specimens, resulting in a sensitivity of 81.8%. This study provides the first large-scale comparison of commercial molecular assays for detection of M. pneumoniae in the United States and identified clear differences among their performance. Additional studies are necessary to explore the impact of various test performances on patient outcome.

Evaluation of the ELITe InGenius PCR Platform for Detection of Mycoplasma pneumoniae.

Mycoplasma pneumoniae is the leading cause of bacterial community-acquired pneumonia in persons of all ages. Due to the fastidious nature of this bacterium and the necessary specialized growth media, nucleic acid amplification testing is currently the most reliable means for patient diagnostics. Analytical sensitivity, specificity, reproducibility, and clinical performance of the ELITe InGenius automated PCR platform with its MGB Alert M. pneumoniae real-time PCR research use only reagents (ELITechGroup, Inc., Bothell, WA) were compared with those of a laboratory-developed real-time PCR assay targeting repMp1 for detection of M. pneumoniae The ELITe InGenius PCR assay successfully detected 31 distinct M. pneumoniae clinical isolates and reference strains, and there was no cross-reactivity with other mollicutes, Gram-positive bacteria, or Gram-negative bacteria. In testing 223 clinical samples, the ELITe InGenius PCR showed 95.79% and 99.22% positive and negative agreement with the repMp1 assay, respectively. Additionally, the ELITech platform showed 98.91% positive and 96.95% negative predictive values, and there was no significant difference detected between the two assays (McNemar's test, P = 0.375). The ELITe InGenius PCR assay limit of detection was 0.16 CFU/PCR test or 4.16 genome copies (GCs)/test. Accuracy, instrument ease-of-use, and decreased hands-on time make the ELITe InGenius platform suitable for detection of M. pneumoniae directly from clinical specimens.

Allergic airway sensitization impairs antibacterial IgG antibody responses during bacterial respiratory tract infections.

BACKGROUND: Mycoplasma pneumoniae, an atypical human pathogen, has been associated with asthma initiation and exacerbation. Asthmatic patients have been reported to have higher carriage rates of M pneumoniae compared with nonasthmatic subjects and are at greater risk for invasive respiratory infections. OBJECTIVE: We sought to study whether prior allergen sensitization affects the host response to chronic bacterial infection. METHODS: BALB/cJ and IL-4 receptor α-/- mice were sensitized with ovalbumin (OVA) and then infected with M pneumoniae or Streptococcus pneumoniae. Immune parameters were analyzed at 30 days postinfection and included cellular profiles in bronchoalveolar lavage fluid (BALF) and serum IgG and IgE antibody levels to whole bacterial lysate, recombinant P1 adhesin, and OVA. Total lung RNA was examined for transcript levels, and BALF was examined for cytokine protein profiles. RESULTS: Anti-M pneumoniae antibody responses were decreased in allergen-sensitized, M pneumoniae-infected animals compared with control animals, but OVA-specific IgG responses were unaffected. Similar decreases in anti-S pneumoniae antibody levels were found in OVA-sensitized animals. However, M pneumoniae, but not S pneumoniae, infection augmented anti-OVA IgE antibody responses. Loss of IL-4 receptor signaling partially restored anti-M pneumoniae antibody responses in IgG2a and IgG2b subclasses. Inflammatory cytokine levels in BALF from OVA-sensitized, M pneumoniae-infected or S pneumoniae-infected animals were reduced compared with those in uninfected OVA-sensitized control animals. Unexpectedly, airway hyperreactivity to methacholine was essentially ablated in M pneumoniae-infected, OVA-sensitized animals. CONCLUSIONS: An established type 2-biased host immune response impairs the host immune response to respiratory bacterial infection in a largely pathogen-independent manner. Some pathogens, such as M pneumoniae, can augment ongoing allergic responses and inhibit pulmonary type 2 cytokine responses and allergic airway hyperreactivity.

Analysis of the tonsillar microbiome in young adults with sore throat reveals a high relative abundance of Fusobacterium necrophorum with low diversity.

Fusobacterium necrophorum (Fn), a gram-negative anaerobe, is increasingly implicated as an etiologic agent in older adolescents and young adults with sore throat. Inadequately treated Fn pharyngitis may result in suppurative complications such as peritonsillar abscess and Lemierre's syndrome. Data from the literature suggest that the incidence of life-threating complications in these age groups from Fn pharyngitis (Lemierre's syndrome) in the United States exceeds those associated with group A beta-hemolytic streptococcal (GAS) pharyngitis (acute rheumatic fever). Using real-time PCR, we previously reported about a 10% prevalence of Fn in asymptomatic medical students and about 20% in students complaining of sore throat at a university student health clinic (p = 0.009). In this study, a comprehensive microbiome analysis of the same study samples confirms that Fn pharyngitis was more common than GAS pharyngitis. Eighteen patients were found to have Fn OTU values exceeding an arbitrary cutoff value of 0.1, i.e. greater than 10% of total sequences, with five subjects reaching values above 0.7. By contrast only 9 patients had GAS OTU values greater than 0.1 and none exceeded 0.6. When the data were analyzed using five separate assessments of alpha diversity, in each case for Fn there were statistically significant differences between Fn positive_high (OTU abundance > 0.1) vs control, Fn positive_high vs Fn negative (OTU abundance = 0), Fn positive_high vs Fn positive_low (OTU abundance > 0 and < 0.1). When the data were analyzed using three beta diversity indexes (Bray-Curtis, weighted unifrac, and unweighted unifrac), there were statistically significant differences between Fn positive_high (OTU abundance ≥ 0.1) vs control for all three. Statistically significant differences remained if we chose somewhat different OTU abundance cutoffs of 0.05 or 0.15. We conclude that Fn appears to play a dominant role in bacterial pharyngitis in the older adolescent and young adult age groups and that the development of a productive mucosal infection with Fn is linked to a significant decrease in the diversity of the associated tonsillar microbiome.

In Vitro Activities of Gepotidacin (GSK2140944) and Other Antimicrobial Agents against Human Mycoplasmas and Ureaplasmas.

Gepotidacin, a novel first-in-class triazaacenaphthylene topoisomerase II inhibitor, was tested against 85 type strains and clinical isolates of Mycoplasma pneumoniae, Mycoplasma hominis, Mycoplasma genitalium, Ureaplasma parvum, and Ureaplasma urealyticum in comparison to levofloxacin, moxifloxacin, azithromycin or clindamycin, and tetracycline. Gepotidacin MIC90s (µg/ml) were 0.125 (M. pneumoniae), 0.032 (M. genitalium), 2 (M. hominis), and 8 (Ureaplasma species). Gepotidacin activity was not affected by resistance to fluoroquinolones, tetracyclines, or macrolides in the strains tested. Gepotidacin merits further study for treating infections caused by these organisms.

Mycoplasma hominis Infections Transmitted Through Amniotic Tissue Product.

Background: Mycoplasma hominis is a commensal genitourinary tract organism that can cause infections outside the genitourinary tract. We investigated a cluster of M. hominis surgical site infections in patients who underwent spine surgery, all associated with amniotic tissue linked to a common donor. Methods: Laboratory tests of tissue product from the donor, including culture, quantitative real-time polymerase chain reaction (qPCR), and whole-genome sequencing were performed. Use of this amniotic tissue product was reviewed. A multistate investigation to identify additional cases and locate any unused products was conducted. Results: Twenty-seven tissue product vials from a donor were distributed to facilities in 7 states; at least 20 vials from this donor were used in 14 patients. Of these, 4 of 14 (29%) developed surgical site infections, including 2 M. hominis infections. Mycoplasma hominis was detected by culture and qPCR in 2 unused vials from the donor. Sequencing indicated >99% similarity between patient and unopened vial isolates. For 5 of 27 (19%) vials, the final disposition could not be confirmed. Conclusions: Mycoplasma hominis was transmitted through amniotic tissue from a single donor to 2 recipients. Current routine donor screening and product testing does not detect all potential pathogens. Clinicians should be aware that M. hominis can cause surgical site infections, and may not be detected by routine clinical cultures. The lack of a standardized system to track tissue products in healthcare facilities limits the ability of public health agencies to respond to outbreaks and investigate other adverse events associated with these products.

In Vitro Activities of Lefamulin and Other Antimicrobial Agents against Macrolide-Susceptible and Macrolide-Resistant Mycoplasma pneumoniae from the United States, Europe, and China.

Lefamulin, an investigational pleuromutilin, was tested against a collection of 18 macrolide-susceptible and 42 macrolide-resistant Mycoplasma pneumoniae strains, and the results were compared with those of azithromycin, erythromycin, tetracycline, doxycycline, and moxifloxacin testing. Lefamulin was highly active against all strains tested, with all MICs at ≤0.008 µg/ml. The lefamulin MIC90 (0.002 µg/ml) for macrolide-resistant strains was the lowest among all drugs tested. Minimum bactericidal concentrations were within 2 dilutions of the MIC values, indicating a bactericidal effect.

Shaken or stirred?: Comparison of methods for dispersion of Mycoplasma pneumoniae aggregates for persistence in vivo.

BACKGROUND: Mycoplasma pneumoniae (Mpn), one of the smallest self-replicating prokaryotes, is known to readily adhere to host cells and to form aggregates in suspension. Having only one cell membrane and no cell wall, mycoplasmas present questions as to optimal aggregate disruption method while minimizing cell death in vitro. We compared conventional vortex mixing with other methods for disruption of bacterial aggregates and for its effect on cell viability. METHODS: Strain UAB PO1, a clinical Mpn isolate, was dispersed using a conventional vortex mixer with or without nonionic detergent (0.1% and 0.01% Tween-20), a probe-type ultrasonicator, or repeated passage through a 27-gauge needle. The resulting suspensions were assayed for recoverable colony-forming units (CFU). Flow cytometric assays were carried out to examine particle size and membrane integrity with the transmembrane potential dye DiBAC4. Wet Scanning Transmission Electron Microscopy (Wet-STEM) was performed for high resolution imaging of the resultant cell suspensions. Additional Mpn strains and other human mollicute species were assayed in a similar manner. Mice were infected with either vortexed or sonicated UAB PO1 and bacterial persistence was examined via Mpn-specific 16S qPCR. RESULTS: Comparison between dispersion methods showed a 10-fold enrichment of recoverable Mpn CFU with sonication compared to other methods. Time-course analysis showed significantly lower bacterial CFU with vortexing compared to sonication at all time points. Flow cytometric analysis showed increased cellular membrane damage via DiBAC4 staining in sonicated suspensions, but a decreased particle size. Wet-STEM imaging showed markedly improved dispersion with sonication compared to conventional vortex treatment, and surprisingly vortexing for 30s produced up to a 100-fold drop in CFU. Results similar to UAB PO1 were obtained with three additional Mpn strains and other Mollicutes species, although they exhibited differential susceptibilities to disaggregation by sonication. Finally, increased persistence of the organism in a mouse model of infection was observed using sonicated suspensions for initial infection. CONCLUSIONS: Sonication is superior to vortexing with or without nonionic detergent or repeated 27-gauge needle passage for dispersion of Mpn aggregates while preserving cell viability. Preparation of Mpn suspensions for in vivo experiments is best accomplished using brief sonication due to the dramatic increase in CFU produced by sonication. Dispersion methods may affect the final experimental results and should be an important consideration for future research involving mycoplasma species.

In Vitro Activities of Omadacycline (PTK 0796) and Other Antimicrobial Agents against Human Mycoplasmas and Ureaplasmas.

In vitro activities of omadacycline, a new aminomethylcycline, were determined for Mycoplasma and Ureaplasma spp. and compared with those of azithromycin, clindamycin, moxifloxacin, tetracycline, and doxycycline. All omadacycline MICs were <2 µg/ml. MIC90s were 0.063 µg/ml for Mycoplasma hominis, 0.25 µg/ml for Mycoplasma pneumoniae, and 2 µg/ml for Ureaplasma spp. Omadacycline had the lowest MIC90 among all drugs tested against M. hominis Omadacycline activity was not affected by macrolide, tetracycline, or fluoroquinolone resistance.

Comparative genome analysis of Mycoplasma pneumoniae.

BACKGROUND: Mycoplasma pneumoniae is a common pathogen that causes upper and lower respiratory tract infections in people of all ages, responsible for up to 40% of community-acquired pneumonias. It also causes a wide array of extrapulmonary infections and autoimmune phenomena. Phylogenetic studies of the organism have been generally restricted to specific genes or regions of the genome, because whole genome sequencing has been completed for only 4 strains. To better understand the physiology and pathogenicity of this important human pathogen, we performed comparative genomic analysis of 15 strains of M. pneumoniae that were isolated between the 1940s to 2009 from respiratory specimens and cerebrospinal fluid originating from the USA, China and England. RESULTS: Illumina MiSeq whole genome sequencing was performed on the 15 strains and all genome sequences were completed. Results from the comparative genomic analysis indicate that although about 1500 SNP and indel variants exist between type1 and type 2 strains, there is an overall high degree of sequence similarity among the strains (>99% identical to each other). Within the two subtypes, conservation of most genes, including the CARDS toxin gene and arginine deiminase genes, was observed. The major variation occurs in the P1 and ORF6 genes associated with the adhesin complex. Multiple hsdS genes (encodes S subunit of type I restriction enzyme) with variable tandem repeat copy numbers were found in all 15 genomes. CONCLUSIONS: These data indicate that despite conclusions drawn from 16S rRNA sequences suggesting rapid evolution, the M. pneumoniae genome is extraordinarily stable over time and geographic distance across the globe with a striking lack of evidence of horizontal gene transfer.

Macrolide-Resistant Mycoplasma pneumoniae, United States.

Macrolide-resistant Mycoplasma pneumoniae (MRMP) is highly prevalent in Asia and is now being reported from Europe. Few data on MRMP are available in the United States. Using genotypic and phenotypic methods, we detected high-level MRMP in 13.2% of 91 M. pneumoniae--positive specimens from 6 US locations.

Specificity and Strain-Typing Capabilities of Nanorod Array-Surface Enhanced Raman Spectroscopy for Mycoplasma pneumoniae Detection.

Mycoplasma pneumoniae is a cell wall-less bacterial pathogen of the human respiratory tract that accounts for > 20% of all community-acquired pneumonia (CAP). At present the most effective means for detection and strain-typing is quantitative polymerase chain reaction (qPCR), which can exhibit excellent sensitivity and specificity but requires separate tests for detection and genotyping, lacks standardization between available tests and between labs, and has limited practicality for widespread, point-of-care use. We have developed and previously described a silver nanorod array-surface enhanced Raman Spectroscopy (NA-SERS) biosensing platform capable of detecting M. pneumoniae with statistically significant specificity and sensitivity in simulated and true clinical throat swab samples, and the ability to distinguish between reference strains of the two main genotypes of M. pneumoniae. Furthermore, we have established a qualitative lower endpoint of detection for NA-SERS of < 1 genome equivalent (cell/µl) and a quantitative multivariate detection limit of 5.3 ± 1 cells/µl. Here we demonstrate using partial least squares- discriminatory analysis (PLS-DA) of sample spectra that NA-SERS correctly identified M. pneumoniae clinical isolates from globally diverse origins and distinguished these from a panel of 12 other human commensal and pathogenic mycoplasma species with 100% cross-validated statistical accuracy. Furthermore, PLS-DA correctly classified by strain type all 30 clinical isolates with 96% cross-validated accuracy for type 1 strains, 98% cross-validated accuracy for type 2 strains, and 90% cross-validated accuracy for type 2V strains.

In vitro antibacterial activity of AZD0914 against human Mycoplasmas and Ureaplasmas.

In this study, susceptibilities were determined for AZD0914, a spiropyrimidinetrione DNA gyrase inhibitor, azithromycin, doxycycline, and levofloxacin against Mycoplasma and Ureaplasma species. The activity of AZD0914 was comparable to that of levofloxacin and doxycycline against Mycoplasma genitalium and Mycoplasma pneumoniae. The AZD0914 MIC90 against Mycoplasma hominis was 8-fold greater than that for levofloxacin. The AZD0914 MIC90 against Ureaplasma species was 4-fold less than that for azithromycin and 8-fold less than that for levofloxacin and doxycycline.