Molecular Epidemiology of Mycoplasma pneumoniae: Genotyping Using Single Nucleotide Polymorphisms and SNaPshot Technology

Genotyping of Mycoplasma pneumoniae strains isolated in Japan during 2019 and 2020: spread of p1 gene type 2c and 2j variant strains

We characterized 118 Mycoplasma pneumoniae strains isolated from three areas of Japan (Saitama, Kanagawa, and Osaka) during the period of 2019 and 2020. Genotyping of the p1 gene in these strains revealed that 29 of them were type 1 lineage (29/118, 24.6%), while 89 were type 2 lineage (89/118, 75.4%), thereby indicating that type 2 lineage was dominant in this period. The most prevalent variant of type 2 lineage was type 2c (57/89, 64%), while the second-most was type 2j, a novel variant identified in this study (30/89, 33.7%). Type 2j p1 is similar to type 2 g p1, but cannot be distinguished from reference type 2 (classical type 2) using the standard polymerase chain reaction-restriction fragment length polymorphism analysis (PCR-RFLP) with HaeIII digestion. Thus, we used MboI digestion in the PCR-RFLP analysis and re-examined the data from previous genotyping studies as well. This revealed that most strains reported as classical type 2 after 2010 in our studies were actually type 2j. The revised genotyping data showed that the type 2c and 2j strains have been spreading in recent years and were the most prevalent variants in Japan during the time-period of 2019 and 2020. We also analyzed the macrolide-resistance (MR) mutations in the 118 strains. MR mutations in the 23S rRNA gene were detected in 29 of these strains (29/118, 24.6%). The MR rate of type 1 lineage (14/29, 48.3%) was still higher than that of type 2 lineage (15/89, 16.9%); however, the MR rate of type 1 lineage was lower than that found in previous reports published in the 2010s, while that of type 2 lineage strains was slightly higher. Thus, there is a need for continuous surveillance of the p1 genotype and MR rate of M. pneumoniae clinical strains, to better understand the epidemiology and variant evolution of this pathogen, although M. pneumoniae pneumonia cases have decreased significantly since the COVID-19 pandemic.

Molecular Tools for Typing Mycoplasma pneumoniae and Mycoplasma genitalium

Mycoplasma pneumoniae and Mycoplasma genitalium are cell wall-less bacteria with strongly reduced genome content and close phylogenetic relatedness. In humans, the only known natural host, the microorganisms colonize the respiratory or genitourinary mucosa and may cause a broad range of clinical presentations. Besides fundamental differences in their tissue specificity, transmission route, and ability to cause prevalence peaks, both species share similarities such as the occurrence of asymptomatic carriers, preferred populations for infection, and problems with high rates of antimicrobial resistance. To further understand the epidemiology of these practically challenging bacteria, typing of strains is necessary. Since the cultivation of both pathogens is difficult and not performed outside of specialized laboratories, molecular typing methods with adequate discriminatory power, stability, and reproducibility have been developed. These include the characterization of genes containing repetitive sequences, of variable genome regions without the presence of repetitive sequences, determination of single and multi-locus variable-number tandem repeats, and detection of single nucleotide polymorphisms in different genes, respectively. The current repertoire of procedures allows reliable differentiation of strains circulating in different populations and in different time periods as well as comparison of strains occurring subsequently in individual patients. In this review, the methods for typing M. pneumoniae and M. genitalium, including the results of their application in different studies, are summarized and current knowledge regarding the association of typing data with the clinical characteristics of infections is presented.

A core genome multilocus sequence typing scheme for Mycoplasma hyorhinis

Mycoplasma (M.) hyorhinis is a commensal and pathobiont residing in the upper respiratory tract in swine and with the ability to spread systemically, mainly causing polyserositis and polyarthritis in nursery pigs. Since little is known on the epidemiology of M. hyorhinis infection, whole genome sequences of 73 strains isolated from pigs in Austria (n = 71) and Germany (n = 2), that have been isolated from clinically affected pigs during routine diagnostics, and publicly available genomes of eight M. hyorhinis strains were analyzed in the presented study. For this purpose, a core genome multi locus sequence typing (cgMLST) scheme encompassing 453 target genes was developed using the Ridom© SeqSphere + software. Results were compared to two previously described conventional MLST schemes and to a core genome single nucleotide polymorphism (cgSNP) analysis approach. Core genome MLST showed high diversity among the M. hyorhinis strains studied and while certain isolates from one farm or a single animal formed cgMLST clusters (≤ 8 allele differences), no isolates with identical allele profiles were identified. In addition, cgMLST had superior discriminatory power (Simpson's ID = 0.995) over conventional MLST (Simpson's ID = 0.952 and 0.985), while demonstrating a lack of congruence between conventional MLST and genome-wide relationship. Core genome SNP results were highly congruent with cgMLST results but lacked in resolution when comparing closely related isolates. Thus, cgMLST is the most suitable method for epidemiological investigations such as outbreak analysis, and to gain insights into M. hyorhinis population structure.

Use of different approaches for the culture-independent typing of Mycoplasma pneumoniae from two geographically distinct regions

We used multi-locus variable-number of tandem repeat analysis (MLVA), p1, multi-locus sequence (MLS) and single nucleotide polymorphisms (SNP) typing to characterize a collection of Mycoplasma pneumoniae strains from Cuba and Germany. Among 67 strains, 5 p1, 7 MLVA, 11 MLS, and 11 SNP types were obtained.

A multisite SNP genotyping and macrolide susceptibility gene method for Mycoplasma pneumoniae based on MALDI-TOF MS

In this study, a multisite SNP genotyping and macrolide (ML) susceptibility gene test method for Mycoplasma pneumoniae (M. pneumoniae) was developed based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The detection limit of this method for nucleic acids was 10² -10³ copies/reaction. Six SNP site-based genotyping and 3 ML susceptibility sites could be detected simultaneously based on multiplex PCR and mass probe. Using the method constructed in this study, 141 Chinese clinical isolates were divided into 8 SNP types. All the SNP test results for the ML susceptibility gene were in line with those of the 23S rRNA sequencing results. With this method, the multisite SNP genotyping and ML susceptibility determination of M. pneumoniae can be completed simultaneously in one test, which greatly reduces the workload and cost, improves the genotyping ability of M. pneumoniae and deserves clinical application.

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An all-in-one genotyping and macrolide resistance testing method for M. pneumoniae

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Multisite SNP detection technology was used for genotyping and resistance testing

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The cost of M. pneumoniae genotyping and macrolide resistance detection was reduced

Molecular Characterization of Mycoplasma pneumoniae Isolates in the United States from 2012 to 2018

Mycoplasma pneumoniae is a major cause of community-acquired pneumonia. There are limited data in the United States on the molecular epidemiological characteristics of M. pneumoniae. We collected 446 M. pneumoniae-positive specimens from 9 states between August 2012 and October 2018. Culture, antimicrobial susceptibility testing, P1 subtyping, and multilocus VNTR (variable-number tandem repeats) analysis (MLVA) were performed to characterize the isolates.

Mycoplasma pneumoniae is a major cause of community-acquired pneumonia. There are limited data in the United States on the molecular epidemiological characteristics of M. pneumoniae. We collected 446 M. pneumoniae-positive specimens from 9 states between August 2012 and October 2018. Culture, antimicrobial susceptibility testing, P1 subtyping, and multilocus VNTR (variable-number tandem repeats) analysis (MLVA) were performed to characterize the isolates. Macrolide-resistant M. pneumoniae (MRMp) was detected in 37 (8.3%) specimens. P1 subtype 2 (P1-2) was the predominant P1 subtype (59.8%). P1 subtype distribution did not change significantly chronologically or geographically. The macrolide resistance rate in P1 subtype 1 (P1-1) samples was significantly higher than that in P1-2 (12.9% versus 5.5%). Six P1-2 variants were identified, including two novel types, and variant 2c was predominant (64.6%). P1-2 variants were distributed significantly differently among geographic regions. Classical P1-2 was more frequent in lower respiratory tract specimens and had longer p1 trinucleotide repeats. Classical P1-2 was most common in MRMp (35.7%), while variant 2c was most common in macrolide-susceptible M. pneumoniae (67.5%). Fifteen MLVA types were identified; 3-5-6-2 (41.7%), 4-5-7-2 (35.3%), and 3-6-6-2 (16.6%) were the major types, and four MLVA clusters were delineated. The distribution of MLVA types varied significantly over time and geographic location. The predominant MLVA type switched from 4-5-7-2 to 3-5-6-2 in 2015. MLVA type was associated with P1 subtypes and P1-2 variant types but not with macrolide resistance. To investigate the M. pneumoniae genotype shift and its impact on clinical presentations, additional surveillance programs targeting more diverse populations and prolonged sampling times are required.

Periodic Genotype Shifts in Clinically Prevalent Mycoplasma pneumoniae Strains in Japan

Nationwide increases in Mycoplasma pneumoniae pneumonia cases in Japan were reported in 2011, 2012, 2015, and 2016. In this study, we isolated 554 M. pneumoniae strains in 4 areas in Japan (Kanagawa, Okayama, Osaka, and Saitama) between 2006 and 2019, and performed genotyping analysis. More than 80% of the strains isolated in 2011 and 2012 harbored type 1 p1 adhesin gene; however, strains harboring type 2 or its variant p1 gene increased in 2015 and 2016 and dominated after 2017. These findings suggested that a shift in the prevalent genotype of M. pneumoniae clinical strains occurred recently in Japan. More than 90% of the type 1 strains isolated after 2010 harbored macrolide-resistance mutations in their 23S rRNA gene, whereas most type 2 lineage strains had no such mutations. Consequently, the increase in type 2 lineage strains in Japan has reduced the macrolide resistance rate of clinical M. pneumoniae strains. During this analysis, we also identified M. pneumoniae strains carrying a novel variant type 1 p1 gene, and we classified it as type 1b. We then sequenced the genomes of 81 selected M. pneumoniae strains that we collected between 1976 and 2017 in Japan, and compared them with 156 M. pneumoniae genomes deposited in public databases to provide insights into the interpretation of M. pneumoniae genotyping methods, including p1 typing, multiple-locus variable-number tandem repeat analysis (MLVA), multi-locus sequence typing (MLST), and typing by 8 single-nucleotide polymorphism markers (SNP-8). As expected, p1 typing, MLST, and SNP-8 results exhibited good correlation with whole-genome SNP analysis results in terms of phylogenetic relationships; however, MLVA typing results were less comparable to those of the other methods. MLVA may be useful for the discrimination of strains derived from a single outbreak within a limited area; however, is not reliable for classification of strains collected from distantly separated areas at different time points. This study showed the usefulness of genome-based comparison of M. pneumoniae for molecular epidemiology. Genome sequencing of more strains will improve our understanding of global propagation routes of this pathogen and evolutionary aspects of M. pneumoniae strains.

Molecular characterization of Mycoplasma pneumoniae infections in Moscow from 2015 to 2018

The aim of this study was to assess which Mycoplasma pneumoniae genotypes were present in Moscow during the years 2015-2018 and whether the proportion between detected genotypes changed over time. We were also interested in the presence of macrolide resistance (MR)Mycoplasma pneumoniae. We performed multilocus variable-number tandem-repeat (VNTR) analysis (MLVA), SNP typing, and mutation typing in the 23S rRNA gene from 117 M. pneumoniae clinical isolates. Our analysis suggests two major MLVA types: 4572 and 3562. In 2017-2018, MLVA type 4572 gradually became predominant. In general, the SNP type range is the same as described earlier for European countries. The analysis of MR mutations showed that 7% of the isolates had an A2063G mutation in the 23S rRNA gene with no isolates carrying an A2064G mutation. In 2017-2018, MLVA type 4572 (SNP type 1) begins to spread in Moscow, which was widespread globally, especially in Asian countries. SNP typing of our sample showed higher discriminatory power than MLVA typing.

Association between the XKR6 rs7819412 SNP and serum lipid levels and the risk of coronary artery disease and ischemic stroke

Background

The present study aimed to expound the association between the XK related 6 gene (XKR6) rs7819412 single nucleotide polymorphism (SNP) and serum lipid profiles and the risk of coronary artery disease (CAD) and ischemic stroke.

Methods

The genetic makeup of the XKR6 rs7819412 SNP in 1783 unrelated participants (controls, 643; CAD, 588 and ischemic stroke, 552) of Han Chinese was obtained by the Snapshot technology.

Results

The genotypic frequencies of the SNP were disparate between CAD (GG, 81.0%; GA/AA, 19.0%) or ischemic stroke (GG, 81.2%; GA/AA, 18.8%) patients and healthy controls (GG, 85.7%, GA/AA, 14.3%; P < 0.05 vs. CAD or ischemic stroke; respectively). The A allele frequency was also diverse between CAD (10.1%) or ischemic stroke (10.0%) and control groups (7.5%; P < 0.05 vs. CAD or ischemic stroke; respectively). The GA/AA genotypes and A allele were associated with high risk of CAD and ischemic stroke (CAD: P = 0.026 for GA/AA vs. GG, P = 0.024 for A vs. G; Ischemic stroke: P = 0.029 for GA/AA vs. GG, P = 0.036 for A vs. G). The GA/AA genotypes were also associated with increased serum triglyceride (TG) concentration in CAD and total cholesterol (TC) concentration in ischemic stroke patients.

Conclusions

These data revealed that the XKR6 rs7819412 A allele was related to increased serum TG levels in CAD, TC levels in ischemic stroke patients and high risk of CAD and ischemic stroke.

Molecular Typing of Mycoplasma pneumoniae Strains in Sweden from 1996 to 2017 and the Emergence of a New P1 Cytadhesin Gene, Variant 2e

Mycoplasma pneumoniae causes respiratory infections, such as community-acquired pneumonia (CAP), with epidemics recurring every 3 to 7 years. In 2010 and 2011, many countries experienced an extraordinary epidemic peak.

Mycoplasma pneumoniae causes respiratory infections, such as community-acquired pneumonia (CAP), with epidemics recurring every 3 to 7 years. In 2010 and 2011, many countries experienced an extraordinary epidemic peak. The cause of these recurring epidemics is not understood, but decreasing herd immunity and shifts in the strains’ antigenic properties have been suggested as contributing factors. M. pneumoniae PCR-positive samples were collected between 1996 and 2017 from four neighboring counties inhabited by 12% of Sweden’s population. A total of 578 isolates were characterized directly from 624 clinical samples using P1 typing by sequencing and multilocus variable number tandem repeat analysis (MLVA). A fluorescence resonance energy transfer (FRET)-PCR approach was also used to detect mutations associated with macrolide resistance in the 23S rRNA gene. Through P1 typing, the strains were classified into type 1 and type 2, as well as variants 2a, 2b, 2c, and a new variant found in nine of the strains, denoted variant 2e. Twelve MLVA types were distinguished, and 3-5-6-2 (42.4%), 4-5-7-2 (37.4%), and 3-6-6-2 (14.9%) predominated. Several P1 and MLVA types cocirculated each year, but type 2/variant 2 strains and MLVA types 3-5-6-2 and 4-5-7-2 predominated during the epidemic period comprising the peak of 2010 and 2011. In 2016 and 2017, type 1 became more common, and MLVA type 4-5-7-2 predominated. We also found that 0.2% (1/578) of the strains carried a macrolide resistance-associated mutation, indicating a very low prevalence of macrolide resistance in this region of Sweden.

A Low-Cost and Simple Genetic Screening for Cystic Fibrosis Provided by the Brazilian Public Health System

Cystic fibrosis newborn screening was implemented in Brazil by the Public Health System in 2012. Because of cost, only 1 mutation was tested - p.Phe508del. We developed a robust low-cost genetic test for screening 11 CFTR gene mutations with potential use in developing countries.

Multiple-Locus Variable-Number Tandem-Repeat Analysis of Mycoplasma pneumoniae Isolates between 2004 and 2014 in Yamagata, Japan: Change in Molecular Characteristics during an 11-year Period

Multiple-locus variable-number tandem-repeat analysis (MLVA) typing was performed for Mycoplasma pneumoniae strains isolated between 2004 and 2014 in Yamagata, Japan. The results were examined by considering the combination of the P1 type and prevalence of macrolide resistance-associated mutations. Four-locus (Mpn13-16) MLVA classified 347 strains into 9 MLVA types, including 3 major types: 3-5-6-2, 4-5-7-2, and 4-5-7-3. All type 3-5-6-2 strains (77 strains) were P1 type 2 variants (2a or 2c), while types 4-5-7-2 (181 strains) and 4-5-7-3 (75 strains) were P1 type 1. MLVA type 4-5-7-2 strains circulated and were dominant until 2010, accounting for 88.4% of the 121 strains isolated between 2004 and 2010. The prevalence of types 4-5-7-3 and 3-5-6-2 strains increased rapidly in 2011 and 2012, respectively, resulting in cocirculation of 3 MLVA types, including type 4-5-7-2, between 2011 and 2013. The prevalence of macrolide resistance-associated mutations in MLVA types 4-5-7-2, 4-5-7-3, and 3-5-6-2 strains was 59.7% (108/181), 25.3% (19/75), and 0% (0/77), respectively. Because the prevalence of macrolide resistance-associated mutations differed by current MLVA types in Yamagata, continued surveillance combined with molecular typing and identification of macrolide resistance-associated mutations is necessary.

Mycoplasma pneumoniae from the Respiratory Tract and Beyond

Mycoplasma pneumoniae is an important cause of respiratory tract infections in children as well as adults that can range in severity from mild to life-threatening. Over the past several years there has been much new information published concerning infections caused by this organism. New molecular-based tests for M. pneumoniae detection are now commercially available in the United States, and advances in molecular typing systems have enhanced understanding of the epidemiology of infections. More strains have had their entire genome sequences published, providing additional insights into pathogenic mechanisms. Clinically significant acquired macrolide resistance has emerged worldwide and is now complicating treatment. In vitro susceptibility testing methods have been standardized, and several new drugs that may be effective against this organism are undergoing development. This review focuses on the many new developments that have occurred over the past several years that enhance our understanding of this microbe, which is among the smallest bacterial pathogens but one of great clinical importance.

Comprehensive bioinformatics analysis of Mycoplasma pneumoniae genomes to investigate underlying population structure and type-specific determinants

Mycoplasma pneumoniae is a significant cause of respiratory illness worldwide. Despite a minimal and highly conserved genome, genetic diversity within the species may impact disease. We performed whole genome sequencing (WGS) analysis of 107 M. pneumoniae isolates, including 67 newly sequenced using the Pacific BioSciences RS II and/or Illumina MiSeq sequencing platforms. Comparative genomic analysis of 107 genomes revealed >3,000 single nucleotide polymorphisms (SNPs) in total, including 520 type-specific SNPs. Population structure analysis supported the existence of six distinct subgroups, three within each type. We developed a predictive model to classify an isolate based on whole genome SNPs called against the reference genome into the identified subtypes, obviating the need for genome assembly. This study is the most comprehensive WGS analysis for M. pneumoniae to date, underscoring the power of combining complementary sequencing technologies to overcome difficult-to-sequence regions and highlighting potential differential genomic signatures in M. pneumoniae.

Complete Genome Sequence of Mycoplasma pneumoniae Type 2 Reference Strain FH Using Single-Molecule Real-Time Sequencing Technology

Mycoplasma pneumoniae type 2 strain FH was previously sequenced with Illumina (FH-Illumina) and 454 (FH-454) technologies according to Xiao et al. (2015) and Krishnakumar et al. (2010). Comparative analyses revealed differences in genomic content between these sequences, including a 6-kb region absent from the FH-454 submission. Here, we present a complete genome sequence of FH sequenced with the Pacific Biosciences RSII platform.

Inter- and intra-strain variability of tandem repeats in Mycoplasma pneumoniae based on next-generation sequencing data

AIM

To characterize inter- and intra-strain variability of variable-number tandem repeats (VNTRs) in Mycoplasma pneumoniae to determine the optimal multilocus VNTR analysis scheme for improved strain typing.

METHODS

Whole genome assemblies and next-generation sequencing data from diverse M. pneumoniae isolates were used to characterize VNTRs and their variability, and to compare the strain discriminability of new VNTR and existing markers.

RESULTS

We identified 13 VNTRs including five reported previously. These VNTRs displayed different levels of inter- and intra-strain copy number variations. All new markers showed similar or higher discriminability compared with existing VNTR markers and the P1 typing system.

CONCLUSION

Our study provides novel insights into VNTR variations and potential new multilocus VNTR analysis schemes for improved genotyping of M. pneumoniae.

Epidemiology of Mycoplasma pneumoniae Infections in Japan and Therapeutic Strategies for Macrolide-Resistant M. pneumoniae

Pneumonia caused by Mycoplasma pneumoniae (M. pneumoniae pneumonia) is a major cause of community-acquired pneumonia worldwide. The surveillance of M. pneumoniae pneumonia is important for etiological and epidemiological studies of acute respiratory infections. In Japan, nation-wide surveillance of M. pneumoniae pneumonia has been conducted as a part of the National Epidemiological Surveillance of Infectious Diseases (NESID) program. This surveillance started in 1981, and significant increases in the numbers of M. pneumoniae pneumonia patients were noted in 1984, 1988, 2006, 2010, 2011, 2012, and 2015. The epidemics in 2011 and 2012 were particularly widespread and motivated researchers to conduct detailed epidemiological studies, including genotyping and drug resistance analyses of M. pneumoniae isolates. The genotyping studies based on the p1 gene sequence suggested that the p1 gene type 1 lineage has been dominant in Japan since 2003, including the epidemic period during 2011-2012. However, more detailed p1 typing analysis is required to determine whether the type 2 lineages become more relevant after the dominance of the type 1 lineage. There has been extensive research interest in implications of the p1 gene types on the epidemiology of M. pneumoniae infections. Serological characterizations of sera from patients have provided a glimpse into these associations, showing the presence of type specific antibody in the patient sera. Another important epidemiological issue of M. pneumoniae pneumonia is the emergence of macrolide-resistant M. pneumoniae (MRMP). MRMPs were noted among clinical isolates in Japan after 2000. At present, the isolation rate of MRMPs from pediatric patients is estimated at 50-90% in Japan, depending on the specific location. In view of the situation, Japanese societies have issued guiding principles for treating M. pneumoniae pneumonia. In these guiding principles, macrolides are still recommended as the first-line drug, however, if the fever does not subside in 48-72 h from first-line drug administration, a change of antibiotics to second-line drugs is recommended.

The Evolution of Advanced Molecular Diagnostics for the Detection and Characterization of Mycoplasma pneumoniae

Over the past decade there have been significant advancements in the methods used for detecting and characterizing Mycoplasma pneumoniae, a common cause of respiratory illness and community-acquired pneumonia worldwide. The repertoire of available molecular diagnostics has greatly expanded from nucleic acid amplification techniques (NAATs) that encompass a variety of chemistries used for detection, to more sophisticated characterizing methods such as multi-locus variable-number tandem-repeat analysis (MLVA), Multi-locus sequence typing (MLST), matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS), single nucleotide polymorphism typing, and numerous macrolide susceptibility profiling methods, among others. These many molecular-based approaches have been developed and employed to continually increase the level of discrimination and characterization in order to better understand the epidemiology and biology of M. pneumoniae. This review will summarize recent molecular techniques and procedures and lend perspective to how each has enhanced the current understanding of this organism and will emphasize how Next Generation Sequencing may serve as a resource for researchers to gain a more comprehensive understanding of the genomic complexities of this insidious pathogen.

Antibody Response to Mycoplasma pneumoniae: Protection of Host and Influence on Outbreaks?

In humans of all ages, the cell wall-less and genome-reduced species Mycoplasma pneumoniae can cause infections of the upper and lower respiratory tract. The well-documented occurrence of major peaks in the incidence of community-acquired pneumonia cases reported world-wide, the multifaceted clinical manifestations of infection and the increasing number of resistant strains provide reasons for ongoing interest in the pathogenesis of mycoplasmal disease. The results of recent studies have provided insights into the interaction of the limited virulence factors of the bacterium with its host. In addition, the availability of complete M. pneumoniae genomes from patient isolates and the development of proteomic methods for investigation of mycoplasmas have not only allowed characterization of sequence divergences between strains but have also shown the importance of proteins and protein parts for induction of the immune reaction after infection. This review focuses on selected aspects of the humoral host immune response as a factor that might influence the clinical course of infections, subsequent protection in cases of re-infections and changes of epidemiological pattern of infections. The characterization of antibodies directed to defined antigens and approaches to promote their induction in the respiratory mucosa are also preconditions for the development of a vaccine to protect risk populations from severe disease due to M. pneumoniae.