Meningoencephalitis caused by Mycoplasma edwardii in a dog

Genomic characterization of Mycoplasma edwardii isolated from a dog bite induced cat wound reveals multiple horizontal gene transfer events and loss of the CRISPR/Cas system

A domestic short hair cat (Felis catus) suffering from a purulent wound infection resulting from a dog bite was sampled for bacterial culture and isolation as the wound had been unresponsive to prolonged antimicrobial treatment. A mycoplasma was isolated from the wound. Whole genome sequencing of the isolate was performed using short-read Illumina and long-read Oxford Nanopore chemistry, and the organism was identified as Mycoplasma edwardii. Comparison of the genome sequence of the isolate to a reference M. edwardii genome sequence (canid isolate) identified the loss of several key bacterial factors involved in genome editing, as well the insertion of several novel ORFs most closely related to those found in other canine mycoplasmas, specifically Mycoplasma canis, M. cynos, M. molare and M. maculosa. This is only the second known report of disease caused by M. edwardii in a non-canid species, and the first report of it infecting and causing clinical disease in a cat.

Detection of Mycoplasma species at various anatomical sites of dogs from different types of kennels

This work aimed to detect Mycoplasma cynos, M. canis, M. edwardii, and M. molare in different types of kennels, in addition to evaluating their distribution in different colonization sites. The dogs belonged to different kennels from armed forces (n = 3), shelters (n = 3), and commercial purposes (n = 2). Samples of the oropharynx, genital mucosa, and ear canal were collected from each dog (n = 98), totaling 294 samples. Aliquots were submitted to isolation and the samples confirmed as Mycoplasma spp. were subjected to conventional PCR for M. canis and multiplex PCR for M. edwardii, M. molare, and M. cynos detection. Of the 98 dogs studied, 63.3% (62) were positive in at least one anatomical site evaluated for Mycoplasma spp. Among the 111 anatomical sites positive for Mycoplasma spp., M. canis, M. edwardii, and M. molare were detected in 29.7% (33/111), 40.5% (45/111), and 2.70% (3/111), respectively. No animal was positive for M. cynos.

Seasonal Variability in the Microbial Community and Pathogens in Wastewater Final Effluents

Numerous bacteria, especially pathogens, exist in wastewater final effluents, which can lead to possible human health and ecological security risks when effluents are reused or discharged. However, the diversity, composition, and spatiotemporal dynamics of bacteria in wastewater final effluents remain poorly understood. In this study, a comprehensive analysis of the microbial community and pathogens in wastewater final effluents was performed using high-throughput sequencing. The results revealed that wastewater final effluents in autumn exhibited the highest bacterial community richness and diversity, while those in winter exhibited the lowest. Bacteria in wastewater final effluents predominantly belonged to five phyla, in the order of Proteobacteria, Actinobacteria, Planctomycetes, Bacteroidetes, and Firmicutes. At the species level, there were 8~15 dominant species in the wastewater final effluent in each season, and Dokdonella immobilis, Rhizobium gallicum, Candidatus Flaviluna lacus, and Planctomyces limnophilus were the most dominant species in spring, summer, autumn, and winter, respectively. The seasonal variability in bacteria suggested that the microbial diversity and community in wastewater final effluents were mainly influenced by temperature, salinity, disinfection methods, and flocculants. Notably, pathogenic bacteria in wastewater effluents had both the highest relative abundance and species abundance in summer. Arcobacter spp., Legionella spp., and Mycobacterium spp. were the dominant pathogenic bacteria, and all pathogenic bacteria were mainly associated with dermatosis, enteropathies, septicemia, and pneumonia.

Mycoplasmas: Brain invaders?

Mycoplasmas of humans and animals are usually associated with respiratory, autoimmune, genital and joint diseases. Human mycoplasmas have also been known to affect the brain. Severe central nervous system (CNS) diseases, such as encephalitis, have been linked to Mycoplasma pneumoniae and ureaplasma infections. Less well known is the sheep and goat pathogen, Mycoplasma agalactiae, which has been found in large quantities in the brain where it may be responsible for non-purulent encephalitis as well as ataxia in young animals. Experimental intra-mammary infections of sheep with this mycoplasma have resulted in histopathological changes in the CNS. The cattle pathogen, M. bovis, has been reported occasionally in the brains of calves and adult cattle showing a range of histopathological lesions including abscesses and fibrinous meningitis. Two avian pathogens, M. gallisepticum and M. synoviae have been isolated from the brains of poultry showing meningeal vasculitis and encephalitis. There have been no reported detections of two other avian pathogens, M. meleagridis or M. iowae in the CNS. Over the last few decades, mycoplasmas have been isolated from the brains of sea mammals dying in large numbers in the North Sea although it was concluded that their role may be secondary to underlying viral disease. Finally, evidence has been advanced that certain Spiroplasma species may have a role in the development of the transmissible spongiform encephalopathies (TSE). Invasion of the brain by mycoplasmas may be as a result of direct entry following damage to the inner ear as seen with M. bovis or across the blood brain barrier by mechanisms as yet uncertain.

Cellular Microbiology of Mycoplasma canis

Mycoplasma canis can infect many mammalian hosts but is best known as a commensal or opportunistic pathogen of dogs. The unexpected presence of M. canis in brains of dogs with idiopathic meningoencephalitis prompted new in vitro studies to help fill the void of basic knowledge about the organism's candidate virulence factors, the host responses that it elicits, and its potential roles in pathogenesis. Secretion of reactive oxygen species and sialidase varied quantitatively (P < 0.01) among strains of M. canis isolated from canine brain tissue or mucosal surfaces. All strains colonized the surface of canine MDCK epithelial and DH82 histiocyte cells and murine C8-D1A astrocytes. Transit through MDCK and DH82 cells was demonstrated by gentamicin protection assays and three-dimensional immunofluorescence imaging. Strains further varied (P < 0.01) in the extents to which they influenced the secretion of tumor necrosis factor alpha (TNF-α) and the neuroendocrine regulatory peptide endothelin-1 by DH82 cells. Inoculation with M. canis also decreased major histocompatibility complex class II (MHC-II) antigen expression by DH82 cells (P < 0.01), while secretion of gamma interferon (IFN-γ), interleukin-6 (IL-6), interleukin-10 (IL-10), and complement factor H was unaffected. The basis for differences in the responses elicited by these strains was not obvious in their genome sequences. No acute cytopathic effects on any homogeneous cell line, or consistent patterns of M. canis polyvalent antigen distribution in canine meningoencephalitis case brain tissues, were apparent. Thus, while it is not likely a primary neuropathogen, M. canis has the capacity to influence meningoencephalitis through complex interactions within the multicellular and neurochemical in vivo milieu.

Broadly reactive polymerase chain reaction for pathogen detection in canine granulomatous meningoencephalomyelitis and necrotizing meningoencephalitis

Background

Granulomatous meningoencephalomyelitis (GME) and necrotizing meningoencephalitis (NME) are common inflammatory conditions of the central nervous system of dogs. Infectious pathogens, particularly viruses, are suspected to contribute to the etiopathogenesis of GME and NME.

Hypothesis

Broadly reactive PCR might aid in the identification of infectious agents in GME and NME.

Animals

Sixty‐eight client‐owned dogs evaluated by necropsy at 1 university referral hospital.

Methods

A mixed prospective/retrospective case‐control study was performed. Brain tissue prospectively collected at necropsy from GME, NME, and control cases was evaluated by broadly reactive polymerase chain reaction (PCR) for adenoviruses, bunyaviruses, coronaviruses, enteroviruses, flaviviruses, herpesviruses, paramyxoviruses, and parechoviruses. In addition, these tissues were retrospectively evaluated for the presence of mycoplasmas by PCR, culture, and immunohistochemistry (IHC).

Results

Brain tissue was collected from 11 GME and 27 NME cases and 30 controls. Viral nucleic acids were not identified in the 6 GME cases, 25 NME cases, and 2 controls evaluated by viral PCR. Mycoplasma canis was identified by Mycoplasma genus PCR in 1/5 GME and 4/25 NME cases and subsequently was cultured from 4/5 GME and 4/8 NME cases as well as 2/9 controls. The IHC did not detect M. canis in any of the 11 GME and 27 NME cases or 14 controls evaluated with strain PG14 polyclonal antiserum.

Conclusions and Clinical Importance

The negative results suggest that viral pathogens are not common in the brain tissue of dogs with GME and NME. Further investigation is warranted to determine the importance of M. canis in cases of GME and NME.