Molecular epidemiology of cases of Mycoplasma californicum infection in Japan

Outbreaks of bovine mastitis caused by specific Mycoplasma bovis strains recurring at multi-year intervals

Mycoplasma bovis is a major cause of bovine mastitis. Intermittent shedding of the organism for many months is a feature of cows with intramammary infection. A dairy farm in Japan experienced a mastitis outbreak caused by M. bovis in 2016, as well as 2 additional outbreaks and 1 case in 2020-2021. The causative strains in the 3 outbreaks shared a common and identical genetic feature, the insertion of a transposase gene at the same site within the phosphate acetyltransferase-2 gene. Additionally, all isolates were genotyped to closely related sequence types (ST21 and ST141) by multilocus sequence typing, and had similar pulsopatterns by pulsed-field gel electrophoresis. Our results indicate that infection with the same causative strain remained in this herd and environment for 4 y. Treatment with fluoroquinolones, guided by antimicrobial susceptibility test results, eliminated M. bovis from 16 of 20 M. bovis-infected cows, as confirmed by culture and somatic cell counts. However, mastitis caused by other bacteria occurred in 9 M. bovis-free cows within 2 mo of the last treatment.

Identification of Mycoplasma species and related organisms from ruminants in England and Wales during 2005-2019

Background

Mycoplasma species have been associated with economically important diseases affecting ruminants worldwide and include contagious bovine pleuropneumonia (CBPP), contagious caprine pleuropneumonia (CCPP) and contagious agalactia, listed by the World Organisation for Animal Health (OIE). The Mycoplasma Team at the Animal and Plant Health Agency provides an identification service for Mycoplasma and Ureaplasma species of veterinary importance to the United Kingdom (UK), supporting the detection of new and emerging pathogens, as well as contributing to the surveillance of endemic, and the OIE listed diseases exotic to the UK. Mycoplasma and other Mollicutes species were identified from diagnostic samples from farmed ruminants in England and Wales using a combination of culture and 16S rRNA gene-based PCR-denaturing gradient gel electrophoresis, submitted between 2005 and 2019.

Results

A total of 5578 mollicutes identifications, which include mycoplasmas and the related acholeoplasmas and ureaplasmas, were made from farmed ruminant animals during the study period. Throughout the study period, the pathogen Mycoplasma bovis was consistently the most frequently identified species, accounting for 1411 (32%) of 4447 molecular identifications in cattle, primarily detected in the lungs of pneumonic calves, followed by joints and milk of cattle showing signs of arthritis and mastitis, respectively. M. bovirhinis, M. alkalescens, M. dispar, M. arginini and Ureaplasma diversum, were also common. Mixed species, principally M. bovis with M. alkalescens, M. arginini or M. bovirhinis were also prevalent, particularly from respiratory samples. The non-cultivable blood-borne haemoplasmas Candidatus ‘Mycoplasma haemobos’ and Mycoplasma wenyonii were identified from cattle, with the latter species most often associated with milk-drop. M. ovipneumoniae was the predominant species identified from sheep and goats experiencing respiratory disease, while M. conjunctivae preponderated in ocular samples. The UK remains free of the ruminant mycoplasmas listed by OIE.

Conclusions

The continued high prevalence of M. bovis identifications confirms its ongoing dominance and importance as a significant pathogen of cattle in England and Wales, particularly in association with respiratory disease. M. ovipneumoniae has seen a general increase in prevalence in recent years, notably in coughing lambs and should therefore be considered as a primary differential diagnosis of respiratory disease in small ruminants.

Detection by multiplex PCR of Mycoplasma species associated with dairy cattle in Argentina

There is scarce information about the frequency and epidemiological and clinical features associated with the presence of Mycoplasma spp. in Argentine dairy herds. The objectives of this study were to develop a multiplex PCR for identifying M.bovis and M.canadense and to describe the frequency of Mycoplasma spp. isolated from clinical samples submitted to a diagnostic laboratory. Of a total of 1548 samples from intramammary infections, bulk tank milk and biological fluids, 38 Mycoplasma isolates were obtained. M. bovis, M. canadense, M.californicum and M.leachii were detected by using two multiplex PCRs, confirming their presence in clinical conditions in dairy cattle. The techniques used in the present study can be useful to broaden the knowledge about Mycoplasma infections in cattle, since the search for these organisms is not usually included in routine diagnoses.

Relationship between Antimicrobial Susceptibility and Multilocus Sequence Type of Mycoplasma bovis Isolates and Development of a Method for Rapid Detection of Point Mutations Involved in Decreased Susceptibility to Macrolides, Lincosamides, Tetracyclines, and Spectinomycin

Mycoplasma bovis isolates belonging to the sequence type 5 (ST5) group, the dominant group in Japan since 1999, were low susceptible to 16-membered macrolides and tetracyclines and were confirmed to have a guanine-to-adenine transition mutation at position 748 in the 23S rRNA gene (rrl) and adenine-to-thymine transversion mutations at positions 965 and 967 in the 16S rRNA gene (rrs) (Escherichia coli numbering). Moreover, isolates of ST93 and ST155, members of the ST5 group, were low susceptible to lincosamides and azithromycin and showed an adenine-to-guanine transition mutation at position 2059 of rrl Isolates of ST93 were additionally low susceptible to spectinomycin and showed a cytosine-to-adenine transversion mutation at position 1192 of rrs Strains of the ST5 group seem to spread to Japan and Europe from North America with imported cows, while strains of ST93 and ST155 originated in Japan. Melting curve analysis using hybridization probes revealed the existence of point mutations involved in decreased susceptibility to macrolides, lincosamides, and spectinomycin, as demonstrated by changes in the melting curve shape and/or decreases in the melting peak temperature, so the susceptibility to these antimicrobials can be assessed on the same day. For decreased susceptibility to fluoroquinolones to exist, nonsynonymous mutations in the DNA gyrase gene (gyrA) and topoisomerase IV gene (parC) had to coexist. The combination of amino acid substitutions of serine at position 83 in gyrA and serine at position 80 in parC resulted in particularly low susceptibility to fluoroquinolones.IMPORTANCE Mycoplasma bovis is the main causal species of bovine mycoplasmal disease and leads to significant economic losses because of its severe symptoms, strong infectivity, and refractoriness. As for mastitis, culling cows with intramammary infections is a general countermeasure to prevent spreading. The conventional antimicrobial susceptibility test for mycoplasma is time-consuming and troublesome, but no quick and easy method for grasping the antimicrobial susceptibility of the causal strain exists at present. Treatment without antimicrobial susceptibility information may be one reason why M. bovis infection is refractory. Detecting a mutation involved in decreased susceptibility to antimicrobial agents of the causal strain makes it possible to easily select suitable antimicrobials for treatment, and this technique will help improve the cure rate and prevent the overuse of ineffective antimicrobial agents. In this study, we developed a technique to quickly and easily assess antimicrobial susceptibility based on the genetic characteristics of M. bovis strains in Japan.

Homogeneity of Mycoplasma agalctiae vaccine strains in an agalaxy- high-burden environment

BACKGROUND AND OBJECTIVES

Interrogation of the genomic relations between Iranian Mycoplasma agalactiae vaccine strains of Taliqan, Lorestan and Shiraz.

MATERIALS AND METHODS

Two MLVA (covering VNTR loci of 5, 9, 17 and 19) and MLST (comprising dnaA, gltX, gyrB, C, tufA genes) genotyping systems plus nucleotide structure analysis of P80 gene, was conducted.

RESULTS

The shared MLVA pattern represented by the three strains differed to that of the Mag PG2 laboratory strain, only at locus VNTR19 where the PG2 genome hold a 3 bp longer stretch. In MLST analysis, at dnaA, gltX, gyrB, metS and tufA loci, the three strains displayed alleles 1, 21, 2, 2 and 1, respectively. At, gltX locus a new allele (21) was detected where a new sequence type (ST33) was identified. Besides, the trio strains hold an identical nucleotide structure in their ma-mp81 gene.

CONCLUSION

In explanation, lack of efficient disease control measures, has possibly contributed in evolution of a clone or a few clones that gradually overwhelmed the population over the time. Besides, the similarity between the Iranian and the PG2 strains, might be due to homoplasy or farming exercises such as animal importation. Inclusion of further local isolates in next studies will help to assess these assumptions.

Mutations associated with change of susceptibility to lincosamides and/or macrolides in field and laboratory-derived Mycoplasma californicum strains in Japan, and development of a rapid detection method for these mutations

Five mutations involved in changing of susceptibility to lincosamides and/or macrolides were investigated in field isolates of Mycoplasma californicum in Japan, and reconfirmed in laboratory-derived mutants. In addition, a quick and easy detection method for these mutations was established. Guanine at position 748 (Escherichia coli numbering) of the 23S rRNA gene (rrl) was shown to be involved with decreased susceptibility to 16-membered macrolides, and adenines at positions 2059 and 2062 of rrl were involved with decreased susceptibility to both lincosamides and macrolides. Both guanine at position 2576, and change from cytosine to thymine at position 2611 of rrl were found to be involved with decreased susceptibility to lincosamides, and the latter mutation also increased the susceptibility to erythromycin. These mutations were easily induced by several to approximately 30 passages in a medium containing the respective antimicrobial, but they did not return after their initial appearance. The melting curve analysis using hybridization probes revealed the existence of these mutations by the change in the melting curve shape and/or decrease in the melting peak temperature. The detection limit in milk samples with a somatic cell count up to 716 × 10³ cell/mL was 133 cfu/mL, but an excessive increase in the cell count in milk or storage of the milk sample at chilling or freezing temperature decreased the sensitivity. This method requires only a few hours, so field veterinarians can make a same-day determination of susceptibility to macrolides and lincosamides, which are first-line antibiotics for bovine mycoplasmal mastitis.

A review of mycoplasma diagnostics in cattle

Mycoplasma species have a global distribution causing serious diseases in cattle worldwide including mastitis, arthritis, pneumonia, otitis media and reproductive disorders. Mycoplasma species are typically highly contagious, are capable of causing severe disease, and are difficult infections to resolve requiring rapid and accurate diagnosis to prevent and control disease outbreaks. This review discusses the development and use of different diagnostic methods to identify Mycoplasma species relevant to cattle, with a particular focus on Mycoplasma bovis. Traditionally, the identification and diagnosis of mycoplasma has been performed via microbial culture. More recently, the use of polymerase chain reaction to detect Mycoplasma species from various bovine samples has increased. Polymerase chain reaction has a higher efficiency, specificity, and sensitivity for laboratory diagnosis when compared with conventional culture‐based methods. Several tools are now available for typing Mycoplasma spp. isolates, allowing for genetic characterization in disease outbreak investigations. Serological diagnosis through the use of indirect ELISA allows the detection of antimycoplasma antibodies in sera and milk, with their use demonstrated on individual animal samples as well as BTM samples. While each testing method has strengths and limitations, their combined use provides complementary information, which when interpreted in conjunction with clinical signs and herd history, facilitates pathogen detection, and characterization of the disease status of cattle populations.

Increase of cells expressing PD-1 and PD-L1 and enhancement of IFN-γ production via PD-1/PD-L1 blockade in bovine mycoplasmosis

Introduction

Bovine mycoplasma, chiefly Mycoplasma bovis, is a pathogen that causes pneumonia, mastitis, arthritis, and otitis media in cattle. This pathogen exerts immunosuppressive effects, such as the inhibition of interferon production. However, the mechanisms involved in bovine mycoplasmosis have not been fully elucidated. In this study, we investigated the role of the programmed death‐1 (PD‐1)/programmed death‐ligand 1 (PD‐L1) pathway in immunosuppression in bovine mycoplasmosis.

Methods

In the initial experiments, we used enzyme‐linked immunosorbent assay to measure interferon‐γ (IFN‐γ) from peripheral blood mononuclear cells (PBMCs) isolated from cattle with mycoplasmosis.

Results

Expectedly, IFN‐γ production significantly decreased in cattle with mycoplasmosis compared with that in clinically healthy cattle. Concomitantly, flow cytometric analysis revealed that the proportions of PD‐1⁺CD4⁺ and PD‐L1⁺CD14⁺ cells significantly increased in peripheral blood of the infected cattle. Interestingly, the number of PD‐1⁺CD4⁺ and PD‐1⁺CD8⁺ T cells were negatively correlated with IFN‐γ production from PBMCs in bovine mycoplasmosis. Additionally, blockade of the PD‐1/PD‐L1 pathway in vitro by anti‐bovine PD‐1‐ and anti‐bovine PD‐L1 antibodies significantly upregulated the production of IFN‐γ from anti‐mycoplasma‐specific cells.

Conclusions

These results suggest that the PD‐1/PD‐L1 pathway could be involved in immune exhaustion of bovine mycoplasma‐specific T cells. In conclusion, our study opens up a new perspective in the therapeutic strategy for bovine mycoplasmosis by targeting the immunoinhibitory receptor pathways.