Corynebacterium suicordis sp. nov., from pigs

Taxonomic reassessment of genomes from a divergent population of Streptococcus suis by average nucleotide identity analysis

Streptococcus spp., including the emerging zoonotic pathogen S. suis, represent a dominant bacterial population in the porcine nasopharynx. Species identification within the Streptococcus genus remains challenging and frequently ambiguous, resulting in indistinct species boundaries. By employing comparative genomic analyses, a previous study categorized S. suis into a central population and divergent lineages, based on the single nucleotide polymorphisms (SNPs) within core genes and the presence or absence of accessory genes, indicating evolutionary divergence. The divergent lineages were designated as the "out population" in this study for clarity. The 16S rRNA gene sequences of seven putative novel Streptococcus strains isolated from the throats of healthy pigs in China exhibited 100 % similarity to that of the 684_17B strain of S. suis, which clustered in the out population. This study established a threshold average nucleotide identity (ANI) value of 93.17 % for the identification of authentic S. suis. All the 645 genomes from the out population fell below this threshold, indicating that they did not belong to S. suis. Further taxonomic assessment of the 645 genomes from the out population revealed 18 clusters based on pairwise ANI comparisons, using a 92.33 % threshold, determined by pairwise ANI comparisons among the 2422 genomes from the central population of S. suis. These clusters were identified as 12 novel Streptococcus spp. (Streptococcus sp. nov-1-12) and six known Streptococcus spp. by ANI comparisons with type or reference genomes of 98 known Streptococcus spp. The study provides a useful framework for the identification of authentic S. suis and the determination of Streptococcus sp. nov.

Diagnosis of bacteria from the CMNR group in farm animals

The CMNR group comprises bacteria of the genera Corynebacterium, Mycobacterium, Nocardia, and Rhodococcus and share cell wall and DNA content characteristics. Many pathogenic CMNR bacteria cause diseases such as mastitis, lymphadenitis, and pneumonia in farmed animals, which cause economic losses for breeders and represent a threat to public health. Traditional diagnosis in CMNR involves isolating target bacteria on general or selective media and conducting metabolic analyses with the assistance of laboratory biochemical identification systems. Advanced mass spectrometry may also support diagnosing these bacteria in the clinic's daily routine despite some challenges, such as the need for isolated bacteria. In difficult identification among some CMNR members, molecular methods using polymerase chain reaction (PCR) emerge as reliable options for correct specification that is sometimes achieved directly from clinical samples such as tracheobronchial aspirates and feces. On the other hand, immunological diagnostics such as the skin test or Enzyme-Linked Immunosorbent Assay (ELISA) for Mycobacterium tuberculosis yield promising results in subclinical infections with no bacterial growth involved. In this review, we present the methods most commonly used to diagnose pathogenic CMNR bacteria and discuss their advantages and limitations, as well as challenges and perspectives on adopting new technologies in diagnostics.

Alteration of Gut Microbiota After Antibiotic Exposure in Finishing Swine

Subclinical doses of antimicrobials are commonly used in the swine industry to control infectious diseases and growth performance. Accumulating evidence suggests that swine administered with antibiotics are susceptible to disease development due to disruption of the beneficial gut microbial community, which is associated with host immune regulation, nutrient digestion, and colonization resistance against pathogens. In this study, we found that finishing swine administered with lincomycin showed gut dysbiosis and increased diarrhea incidence compared with control swine. 16S rRNA amplicon sequencing was used to analyze the gut microbiota in finishing swine administered with lincomycin. The relative abundance of detrimental microbes, such as species of Clostridium, Aerococcus, Escherichia-Shigella, and Corynebacterium was increased in the feces of lincomycin-administered finishing swine, but that of bacteria associated with fiber degradation, such as species of Treponema, Succinivibrio, Fibrobacter, and Cellulosilyticum was decreased. Moreover, administration of lincomycin significantly increased the enrichment of metabolic pathways related to pathogenicity and deficiency of polysaccharide degradation. These results suggest that lincomycin treatment could cause severe disruption of the commensal microbiota in finishing swine.

Correlation between invasive microbiota in margin-surrounding mucosa and anastomotic healing in patients with colorectal cancer

BACKGROUND

Impaired anastomotic healing is one of the major complications resulting from radical resection in colorectal cancer (CRC). Accumulating evidence suggests that intestinal microbiota is correlated with anastomotic healing.

AIM

To explore the microbiota structural shift in margin-surrounding mucosa and evaluate the predictive ability of selected bacterial taxa for impaired anastomotic healing.

METHODS

Margin-surrounding mucosa samples derived from 37 patients were collected to characterize the microbial community structure by 16s rRNA gene sequencing. The patients were divided into two groups according to the healing status of anastomoses: well-healing group (n = 30) and impaired-healing group (n = 7). Statistic differences in bacteria taxa were compared by Wilcoxon test and chi-squared test. The predictive ability of the selected bacterial taxa for the healing status of anastomoses was evaluated by the area under the receiver operator characteristic curve.

RESULTS

Community structure shifts were observed in the impaired-healing group and well-healing group. Six bacterial species were found to be significantly correlated with anastomotic healing, and among these species, Alistipes shahii, Dialister pneumosintes, and Corynebacterium suicordis were considered as the predictive factors. Taking the known risk factor age into consideration, Alistipes shahii, Dialister pneumosintes, and Corynebacterium suicordis improved predictive ability for the healing status of anastomoses.

CONCLUSION

These data show that Alistipes shahii, Dialister pneumosintes, and Corynebacterium suicordis could be considered as supplementary factors in the prediction of anastomosis healing status in patients after CRC radical resection.

Multi-Etiological Nature of Tuberculosis-Like Lesions in Condemned Pigs at the Slaughterhouse

Tuberculosis-like lesions (TBL) in pigs have been associated with microorganisms other than mycobacteria. In this work a histopathological and microbiological evaluation of TBL in pigs is shown. A total of 352 samples belonging to 171 pigs totally condemned at slaughterhouse due to generalized TBL were sampled and selected for analysis. Pyogranulomatous (56.2%) and granulomatous lesions (20.2%) were observed in all analysed organs. Most of the granulomas observed in both lymph nodes and lungs belonged to more advanced stages of development (stages III and IV) whereas in the liver and the spleen most of lesions belonged to intermediate stages (stages II and III). Different microorganisms were simultaneously detected from TBL in the 42.7% of the animals. Mycobacterium tuberculosis complex (MTC) (38%), coryneform bacteria (40.3%) and streptococci (28.1%) were the main groups of microorganisms detected after bacteriological analysis, with Trueperella pyogenes and Streptococcus suis as the most frequently isolated species. Mycobacteria belonging to MTC were the most frequently detected pathogens in granulomatous and pyogranulomatous lesions in submandibular lymph nodes (32.7%) and coryneform bacteria were the microorganisms more frequently isolated from lungs (25.9%) and spleen samples (37.2%). These results may provide new insights into the pathogenesis and diagnosis of this pathology. The importance of coryneform bacteria and streptococci in such processes must be evaluated in future studies.

Complete Genome Sequence of the Type Strain Corynebacterium testudinoris DSM 44614, Recovered from Necrotic Lesions in the Mouth of a Tortoise

The complete genome sequence of the type strain Corynebacterium testudinoris DSM 44614 from the mouth of a tortoise comprises 2,721,226 bp with a mean G+C content of 63.14%. The automatic annotation of the genome sequence revealed 4 rRNA operons, 51 tRNA genes, 7 other RNA genes, and 2,561 protein-coding regions.

Non-contiguous finished genome sequence of Corynebacterium timonense type strain 5401744(T.)

Corynebacterium timonense strain 5401744^T is a member of the genus Corynebacterium which contains Gram-positive bacteria with a high G+C content. It was isolated from the blood of a patient with endocarditis. In this work, we describe a set of features of this organism, together with the complete genome sequence and annotation. The 2,553,575 bp long genome contains 2,401 protein-coding genes and 55 RNA genes, including between 5 and 6 rRNA operons.

Corynebacterium spp. in Dogs and Cats with Otitis Externa and/or Media: A Retrospective Study

The role of Corynebacterium spp. in the pathogenesis of canine and feline otitis externa/media and their appropriate antimicrobial therapy are unclear. The objectives of this study were to (1) better establish the pathogenicity of Corynebacterium spp. in otitis utilizing reported criteria and by assessing clinical response to antibiotic therapy and (2) to determine the antimicrobial susceptibility patterns of Corynebacterium spp. associated with otitis. The study was retrospective, targeting cultures positive for Corynebacterium spp. Corynebacterium spp. were part of mixed microbial populations in 79/81 cultures. Corynebacterium spp. pathogenicity was highly questionable because of their almost invariable presence with other microbes and the observation that Corynebacterium spp. usually disappear from the ear with resolution of other infections, even when the Corynebacterium spp. are resistant to the prescribed antibiotic(s). However, 2/81 cultures came from two canine ears wherein Corynebacterium spp. may have been pathogenic. Antimicrobial sensitivities for Corynebacterium spp. were available for 54 isolates. Most isolates were susceptible to chloramphenicol (53/54), amikacin (50/54), tetracycline (50/54), gentamicin (46/54), and enrofloxacin (32/54). Among those antibiotics available in otic products, gentamicin and enrofloxacin would be rational choices for the empirical, topical therapy of Corynebacterium spp.

Characterization of some bacterial strains isolated from animal clinical materials and identified as Corynebacterium xerosis by molecular biological techniques

Eighteen Corynebacterium xerosis strains isolated from different animal clinical specimens were subjected to phenotypic and molecular genetic studies. On the basis of the results of the biochemical characterization, the strains were tentatively identified as C. xerosis. Phylogenetic analysis based on comparative analysis of the sequences of 16S rRNA and rpoB genes revealed that the 18 strains were highly related to C. xerosis, C. amycolatum, C. freneyi, and C. hansenii. There was a good concordance between 16S rRNA and partial rpoB gene sequencing results, although partial rpoB gene sequencing allowed better differentiation of C. xerosis. Alternatively, C. xerosis was also differentiated from C. freneyi and C. amycolatum by restriction fragment length polymorphism analysis of the 16S-23S rRNA gene intergenic spacer region. Phenotypic characterization indicated that besides acid production from D-turanose and 5-ketogluconate, 90% of the strains were able to reduce nitrate. The absence of the fatty acids C(14:0), C(15:0), C(16:1)omega 7c, and C(17:1)omega 8c can also facilitate the differentiation of C. xerosis from closely related species. The results of the present investigation demonstrated that for reliable identification of C. xerosis strains from clinical samples, a combination of phenotypic and molecular-biology-based identification techniques is necessary.

Corynebacterium canis sp. nov., isolated from a wound infection caused by a dog bite

A non-lipophilic, coryneform bacterium isolated from a patient's wound caused by a dog bite was characterized by phenotypic, chemotaxonomic and molecular genetic methods. Chemotaxonomic features suggested assignment of the unknown bacterium to the genus Corynebacterium. The isolate exhibited the following unusual features, which made it possible to phenotypically differentiate it from all other medically relevant corynebacteria: the Gram stain showed some very filamentous rods (>15 μm in length); some cells exhibited branching; colonies were domed and adherent to agar; the micro-organism was positive for pyrazinamidase, β-glucosidase, α-glucosidase and trypsin but negative for β-galactosidase. 16S rRNA gene sequencing and partial rpoB gene sequencing showed that the closest phylogenetic relative, Corynebacterium freiburgense, exhibited more than 1.9 % and 17.9 % divergence with the unknown bacterium, respectively. Based on both phenotypic and molecular genetic data, it is proposed that the isolate should be classified as a novel species, Corynebacterium canis sp. nov., with the type strain 1170(T) (=CCUG 58627(T) =DSM 45402(T)).

Corynebacterium timonense sp. nov. and Corynebacterium massiliense sp. nov., isolated from human blood and human articular hip fluid

Gram-positive, facultatively anaerobic, rod-shaped bacteria were isolated from the blood of a patient with endocarditis (strain 5401744T) and from the hip joint fluid of a patient with an infected orthopaedic prosthesis (strain 5402485T). These strains were characterized by using a polyphasic taxonomic approach. Based on cellular morphology and biochemical criteria the two isolates were tentatively assigned to the genus Corynebacterium, although they did not correspond to any recognized species. The predominant fatty acids were a mix of C18:2omega6,9c and anteiso-C18:0 (32.1% of the total), C16:0 (26.3%) and C18:1omega9c (22.5%) for strain 5402485T and C18:1omega9c (36.4%), C17:1omega9c (27.1%) and C16:0 (10.9%) for strain 5401744T. Phylogenetic analysis based on 16S rRNA gene sequence comparisons showed that strain 5401744T was closely related to the type strains of Corynebacterium auris, Corynebacterium capitovis, Corynebacterium lipophiloflavum and Corynebacterium mycetoides (97.0, 96.6, 96.5 and 96.3% similarity, respectively) and strain 5402485T was closely related to the type strains of Corynebacterium macginleyi, Corynebacterium accolens, Corynebacterium tuberculostearicum, Corynebacterium confusum, Corynebacterium mastitidis and Corynebacterium renale (95.6, 95.3, 95.3, 94.5, 94.0 and 93.5%, respectively). On the basis of phenotypic data and phylogenetic inference, these isolates are considered to represent two novel species of the genus Corynebacterium, for which the names Corynebacterium timonense sp. nov. (type strain, 5401744T=CSUR P20T=CIP 109424T=CCUG 53856T) and Corynebacterium massiliense sp. nov. (type strain, 5402485T=CSUR P19T=CIP 109423T=CCUG 53857T) are proposed.

Upregulation of galectin-3 by Corynebacterium kutscheri infection in the rat lung

Corynebacterium (C) kutscheri and Staphylococcus aureus were isolated from two Sprague-Dawley (SD) rats with a hemisected spinal cord. Grossly, gray-white bulging foci and abscesses were distributed throughout the parenchyma of the lung. Pathologically, severe necrotizing lobar pneumonia with abscesses and fibrinous pleuritis were observed. Immunohistochemical analysis found accumulation of galectin-3 in alveolar macrophages and the alveolar interstitial region. No other viral or bacterial pathogens were detected in these animals. In addition, similar pathogenic changes and accumulation of galectin-3 were observed in the lungs of SD rats experimentally infected with C. kutscheri. Using northern blot analysis, the relative galectin-3 and GAPDH mRNA levels were 4.6 to 9.3 times higher in C. kutscheri-infected lung than in uninfected controls. These results demonstrate that a single C. kutscheri infection can induce the upregulation of galectin-3 in the lung and that this molecule may have an important pathogenic role in C. kutscheri infections in rats.

Isolation of Corynebacterium xerosis from animal clinical specimens

This article describes the first identification of Corynebacterium xerosis from animal clinical specimens, which was confirmed by microbiological and molecular genetic (16S rRNA gene sequencing) methods.