Streptococcus canis infections in humans: Retrospective study of 54 patients

Streptococcus dysgalactiae subsp. equisimilis infection and its intersection with Streptococcus pyogenes

SUMMARYStreptococcus dysgalactiae subsp. equisimilis (SDSE) is an increasingly recognized cause of disease in humans. Disease manifestations range from non-invasive superficial skin and soft tissue infections to life-threatening streptococcal toxic shock syndrome and necrotizing fasciitis. Invasive disease is usually associated with co-morbidities, immunosuppression, and advancing age. The crude incidence of invasive disease approaches that of the closely related pathogen, Streptococcus pyogenes. Genomic epidemiology using whole-genome sequencing has revealed important insights into global SDSE population dynamics including emerging lineages and spread of anti-microbial resistance. It has also complemented observations of overlapping pathobiology between SDSE and S. pyogenes, including shared virulence factors and mobile gene content, potentially underlying shared pathogen phenotypes. This review provides an overview of the clinical and genomic epidemiology, disease manifestations, treatment, and virulence determinants of human infections with SDSE with a particular focus on its overlap with S. pyogenes. In doing so, we highlight the importance of understanding the overlap of SDSE and S. pyogenes to inform surveillance and disease control strategies.

Genetic organization of an M protein trans-acting positive regulator (Mga) orthologue and its adjacent M-like protein (SCM) alleles in Streptococcus canis

OBJECTIVE

The purpose of this study was to identify the M protein trans-acting positive regulator (Mga) orthologue and its adjacent M-like protein (SCM) alleles in Streptococcus canis.

RESULTS

Using the 39 SCM allele isolates and polymerase chain reaction-based amplification and sequencing, we obtained the deduced Mga amino acid (AA) sequences. The 22 Mga sequences in whole-genome sequences were obtained by searching the National Collection of Type Cultures 12,191(T) Mga sequence into the database. The percentage identity to the type-strain Mga sequence was examined along with its size. The presence of the Mga-specific motifs was confirmed. Of the 62 strains, we identified 59 Mga sequences with an AA size of 509 (except for four different sizes). Percentage identity ranged from 96.66 to 100% with the confirmed Mga-specific motifs and diverse SCM allele populations. Our findings support the presence of an Mga orthologue and diverse SCM allele populations.

Multiple Drug Resistant Streptococcus Strains-An Actual Problem in Pig Farms in Western Romania

Streptococci are a type of bacteria that can cause severe illnesses in humans and animals. Some typical species like S. suis, or atypical species like S. porcinus and, S. dysgalactiae subsp. dysgalactiae, can cause infections like septicemia, meningitis, endocarditis, arthritis, and septic shock. S. suis is considered a newly emerging zoonotic pathogen. Although human streptococcal infection outbreaks are rare, it is appropriate to review the main streptococcal species isolated in pig farms in western Romania, due to the high degree of antibiotic resistance among most isolates commonly used in human treatment. This study examines the resistance patterns of these isolates over 5 years (2018-2023). The research investigated the antimicrobial susceptibility of 267 strains of Streptococcus spp. isolated from pigs, primarily from lung and brain tissues. This report is the first to describe the distribution of atypical Streptococcus species (SDSE, S. porcinus, S. hyovaginalis, S. pluranimalium, S. canis) in Romania, as well as the antibiotic resistance profile of these potentially zoonotic species. It is important to re-evaluate and consider the high rates of resistance of S. suis to tetracyclines, lincosamides, macrolides, and aminoglycosides, as well as the high recovery rates of S. suis from the lungs and brain when treating swine diseases.

Two episodes of bacteremia of zoonotic origin caused by different Streptococcus canis isolates in the same patient within a time span of 1 year

Two episodes of bacteremia of cutaneous origin in a female patient were caused by two unrelated Streptococcus canis isolates within 1-year interval between the two infection episodes. The most likelihood transmission route in both episodes was a dog pet that habitually licked patient´s legs. Isolates were characterised by antimicrobial susceptibility test and whole genome sequencing. They belonged to sequence type (ST) 40 and 43, respectively. The ST40 isolate harboured antimicrobial resistance genes aadE, ermB and tetO, displaying resistance to erythromycin, clindamycin and tetracyclines, while ST43 isolate did not presented any known antimicrobial resistance determinant and was susceptible to all antibiotics tested. S. canis infections are rare in human; however, attention is needed for patients at risk with companion animals.

Chronic Fistulas of Thigh Presenting Unusually in an Operated Patient of Carcinoma Rectum. More Than What Meets the Eye!

Chronic skin lesions of the thigh (wounds, fistulas etc) are relatively uncommon, vis-à-vis, their notorious cousins over the distal limb. Even when present, the cause is usually obvious, mostly as trauma or a systemic affliction. We present an unusual case of chronic fistulas over the right thigh in a patient of carcinoma rectum for which anterior resection and an end colostomy was done 4 years earlier. Postsurgical pelvic abscesses finding their way into the thigh are a known entity, but they are usually accompanied by systemic/local features and their presentation is within a shorter time span. The novelty of our case lies in its manifestation (as a cluster of chronic fistulas and not a frank abscess), its late presentation as well as in the absence of any systemic/local inflammatory signs. Our primary objective is to educate wound physicians about the origin of such fistulas whenever they deal with patients who have had a preceding surgical intervention of the abdomen. In our humble opinion, this will ease out many diagnostic and management dilemmas, that such patients can potentially pose.

Malicious Mites-Sarcoptes scabiei in Raccoon Dogs (Nyctereutes procyonoides) in Schleswig-Holstein, Germany

Sarcoptic mange was detected in five free-ranging raccoon dogs (Nyctereutes procyonoides) in the federal state of Schleswig-Holstein, Germany, during a health assessment study of invasive species, including raccoon dogs, carried out between 2021 and 2022. Four raccoon dogs showed severe lesions, including extensive alopecia with thickening and hyperpigmentation of the skin (lichenification). The fifth animal was less affected, showing only thinning of the hair coat in multiple body locations. Skin scrapings were performed and confirmed the presence of Sarcoptes scabiei. Histopathology of the skin revealed diffuse epidermal hyperplasia and hyperkeratosis, mild eosinophilic dermatitis, and varying amounts of intralesional mites. Staphylococcus pseudintermedius and Corynebacterium auriscanis were detected in the skin samples of the affected animals, indicating a secondary bacterial infection. The source of sarcoptic mange remains unclear; interspecies transmission via direct or indirect contact seems likely. Raccoon dogs are therefore a potential vector for sarcoptic mange, and their behaviour could contribute to disease spread and persistence.

The type-2 Streptococcus canis M protein SCM-2 binds fibrinogen and facilitates antiphagocytic properties

Streptococcus canis is a zoonotic agent that causes severe invasive diseases in domestic animals and humans, but little is known about its pathogenesis and virulence mechanisms so far. SCM, the M-like protein expressed by S. canis, is considered one of the major virulence determinants. Here, we report on the two distinct groups of SCM. SCM-1 proteins were already described to interact with its ligands IgG and plasminogen as well as with itself and confer antiphagocytic capability of SCM-1 expressing bacterial isolates. In contrast, the function of SCM-2 type remained unclear to date. Using whole-genome sequencing and subsequent bioinformatics, FACS analysis, fluorescence microscopy and surface plasmon resonance spectrometry, we demonstrate that, although different in amino acid sequence, a selection of diverse SCM-2-type S. canis isolates, phylogenetically representing the full breadth of SCM-2 sequences, were able to bind fibrinogen. Using targeted mutagenesis of an SCM-2 isolate, we further demonstrated that this strain was significantly less able to survive in canine blood. With respect to similar studies showing a correlation between fibrinogen binding and survival in whole blood, we hypothesize that SCM-2 has an important contribution to the pathogenesis of S. canis in the host.

Fibrinous pleuritis associated with Streptococcus canis in a leopard cat (Prionailurus bengalensis euptilurus)

Leopard cat (Prionailurus bengalensis euptilurus) is a small wild cat assessed as an endangered wildlife in Korea. There have been very few reports of their diseases. Herein, we describe fibrinous pleuritis caused by Streptococcus canis infection with excessive pleural effusion, hydropericardium, mild ascites, and liver fibrosis in a leopard cat. S. canis is a commensal microflora in domestic cats and often affects the upper respiratory tract inducing chronic and severe respiratory diseases. However, there is no literature regarding the S. canis in leopard cats. Therefore, we first report fibrinous pleuritis associated with an S. canis infection in a leopard cat.

Streptococcus canis prostatitis and endocarditis with thromboembolism in a dog with sertoli cell tumour in a cryptic testis and prostatic squamous metaplasia

We describe an unusual case of prostatitis caused by Streptococcus canis evolving to endocarditis and splenic, renal, and cerebral thromboembolism in a dog, associated with a Sertoli cell tumour in a cryptic testis and diffuse prostatic squamous metaplasia. A nine-year-old, intact male, mixed-breed dog was presented to a veterinary teaching hospital with abdominal pain and prostration. Physical examination and abdominal ultrasonography revealed an atrophic right testicle located in the subcutaneous tissue. The left testicle was in the abdominal cavity with increased dimensions and irregular contours. Complete blood count analysis showed marked neutrophilic leukocytosis and thrombocytopenia. After clinical worsening, euthanasia was performed, and the dog was submitted to post-mortem examination. The main gross findings included testicular malposition with one cryptic and one ectopic testis, enlarged prostate with purulent content, distension of the urinary bladder with cloudy urine, vegetative valvular endocarditis in the mitral valve, and spleen and renal infarcts. Histological examination showed a Sertoli cell tumour in the abdominal testis, diffuse prostatic squamous metaplasia with marked keratinization associated with bacterial prostatitis, fibrinonecrotic cystitis, bacterial endocarditis with marked myxomatous degeneration in the mitral valve, and splenic, renal, and cerebral thromboembolism. Microbiological analysis identified Streptococcus canis in the prostate and mitral valve. Sertoli cell tumour of cryptic testis increases oestrogen production and leads to squamous metaplasia of the prostate, which should be considered as predisposing factors for ascending S. canis infection from the urogenital tract to the prostate. Then, haematogenous spread of S. canis from the prostate to mitral valve cause endocarditis and subsequent thromboembolism and infarcts, all decisive to poor prognosis in this case.

Tetracycline, Macrolide and Lincosamide Resistance in Streptococcus canis Strains from Companion Animals and Its Genetic Determinants

Growing antimicrobial resistance (AMR) in companion-animal pathogens, including Streptococcus canis (S. canis), is a significant concern for pet treatment as well for public health. Despite the importance of S. canis in veterinary and human medicine, studies concerning the AMR of this bacterium are still scarce. A total of 65 S. canis strains, isolated from dogs and cats, were assessed to test for susceptibility to six clinically relevant antimicrobials via a microdilution method. The prevalence of the selected acquired-resistance genes was also investigated via PCR. High MIC50 and MIC90 values (≥128 μg/mL) were noted for tetracycline, erythromycin and clindamycin. Only a few strains were resistant to the tested beta-lactams (6.2%). Tetracycline resistance was found in 66.2% of the strains. Resistance to erythromycin and clindamycin (ML resistance) was found in 55.4% of the strains. Strains with a phenotype showing concurrent resistance to tetracycline and ML were predominant (53.8%). AMR in the tested S. canis strains was associated with a variety of acquired and potentially transferable genes. Tetracycline resistance was conferred by tet(O) (40.0%), tet(M) (9.2%), and tet(T) (1.5%), which is reported for the first time in S. canis. In most cases, the tet(M) gene was detected in relation to the conjugative transposon Tn916. The MLSB phenotype was confirmed in the strains harboring erm(B) (43.1%) and erm(TR) (7.7%). To conclude, a high rate of S. canis strains occurring in dogs and cats displayed resistance to antimicrobials important for treatment; moreover, they are a potential reservoirs of various resistance determinants. Therefore, AMR in these pathogens should be continuously monitored, especially regarding the One Health concept.

Genotypic and phenotypic features of eye-origin Streptococcus canis isolates from dogs in 2021: relatedness with clonal complex 46 and antimicrobial resistance

Eye (including cornea) and ear canal are major sources of Streptococcus canis in companion animal practice. We aimed to clarify genotypic and phenotypic features of the eye-origin isolates in 2021 compared to ear-origin isolates in 2021 and eye-origin isolates in 2017. Of the 102 isolates in 2021, nine eye-origin isolates were enrolled, whereas twenty-one ear-origin isolates in 2021 and thirteen eye-origin isolates in 2017 were included as controls. Genotypic analyses included virulence-associated gene (VAG; inl, sagA, slo, scp, lbp, fbp, gbp, ap1, fp1, and brp) profiling, S. canis M-like protein (SCM) allele typing, multilocus sequence typing, and antimicrobial resistance (AMR) genotyping: phenotypic analyses contained hemolytic activity (HA) measurement and AMR phenotyping. There was only one 2017-eye-origin isolate with high-level HA, while the others showed low-level HA. We observed no association of the 2021-eye-origin population with detection rate of each VAG. There was no association of the 2021-eye-origin population with main SCM allele 2. We found significant association of the 2021-eye-origin population with main clonal complex (CC) 46 containing sequence type (ST) 46/ST2. There was significant association of the 2021-eye-origin population with AMR phenotypes/genotypes. Our observations suggest the unique microbiological features (CC46 having AMR phenotypes/genotypes) among the 2021-eye-origin population.

A case of Streptococcus canis bacteremia, osteomyelitis, sacroiliitis, myositis, and abscess

Background

Streptococcus canis is a group G beta-hemolytic Streptococcus species which normally resides on the skin and mucosal surfaces of dogs. Although it rarely causes infection in humans, our case and review of relevant literature demonstrate that this multi-host pathogen may be responsible for metastatic infection. We present an appropriate management strategy in such cases.

Case presentation

A previously healthy 26-year-old male presented to the emergency department with a 2-day history of erythema, pain, and swelling of the left ankle and foot, consistent with acute cellulitis. The patient was initially discharged home with a plan to complete a course of IV cefazolin as an outpatient, but later recalled after two sets of blood cultures grew gram positive cocci. Blood cultures speciated as Streptococcus canis. This was performed by identifying beta hemolytic strep on blood agar, then typed as Lancefield group G, followed by MALDI-TOF which distinguished S. canis. History was unremarkable except for a 2-week history of lower back pain precipitated by a wrestling injury. There was no canine bite or scratch wound, although the patient lives with a dog. CT spine was obtained which demonstrated right piriformis myositis and S1 osteomyelitis. MRI additionally demonstrated right erector spinae myositis, right sacroiliitis, and multiple collections in the right posterior paraspinal soft tissues. Transthoracic echocardiogram did not demonstrate valvular vegetations. The S. canis isolate was pan-susceptible and the patient was ultimately discharged home and completed a 8-week course of IV penicillin G. After completion of therapy, his symptoms, repeat imaging, and biochemical markers suggested resolution of infection on follow-up.

Conclusions

We suggest that management of S. canis bacteremia should involve consideration of screening for metastatic infection and infectious diseases consultation. However, despite its potential for systemic involvement, S. canis is often susceptible to narrow spectrum antibiotics, and may be treated with penicillins.

S. canis does not require a clear portal of entry to cause infection

When S. canis infection is identified, screening for sites of metastatic infection should be considered

S. canis infection is typically susceptible to narrow-spectrum antibiotics

Distribution, Diversity and Roles of CRISPR-Cas Systems in Human and Animal Pathogenic Streptococci

Streptococci form a wide group of bacteria and are involved in both human and animal pathologies. Among pathogenic isolates, differences have been highlighted especially concerning their adaptation and virulence profiles. CRISPR-Cas systems have been identified in bacteria and many streptococci harbor one or more systems, particularly subtypes I-C, II-A, and III-A. Since the demonstration that CRISPR-Cas act as an adaptive immune system in Streptococcus thermophilus, a lactic bacteria, the diversity and role of CRISPR-Cas were extended to many germs and functions were enlarged. Among those, the genome editing tool based on the properties of Cas endonucleases is used worldwide, and the recent attribution of the Nobel Prize illustrates the importance of this tool in the scientific world. Another application is CRISPR loci analysis, which allows to easily characterize isolates in order to understand the interactions of bacteria with their environment and visualize species evolution. In this review, we focused on the distribution, diversity and roles of CRISPR-Cas systems in the main pathogenic streptococci.

Comparative genomic features of Streptococcus canis based on the pan-genome orthologous group analysis according to sequence type

Using bacterial pan-genome obtained through whole genome sequencing (WGS), coding DNA sequences (CDSs) can be clustered into pan-genome orthologous groups (POGs). We aimed to investigate comparative genomic features of Streptococcus canis based on POG analysis and to determine CDSs specific to prevalent sequence type (ST) 9. Twenty WGS datasets on S. canis strains from invasive and non-invasive specimens were retrieved from the National Center for Biotechnology Information Assembly database. Based on the WGS data, we performed comparative genome hybridization (CGH), pan- and core-genome prediction, Venn diagram test with five ST9 strains, and phylogenetic analysis, with ST determination. We compared the CDSs between seven ST9 and 13 non-ST9 strains. We observed genomic diversity based on CGH and Venn diagram. The predicted pan- and core-genomes contained 4,772 and 1,403 genes, respectively. We found five clades consisting of different STs (ST1, ST44/2, ST13/14, ST21/15/41, and ST9) based on phylogenetic tree. There were differences in four pathways (DNA restriction-modification system, DNA-mediated transposition, extracellular region, and response to oxidative stress) regulated by CDSs specific to ST9. Our findings describe genomic diversity in CGH and Venn diagram, pan- and core-genomes, five clades of genomes consisting of different STs, and unique CDS features associated to ST9.

Biofilm production ability and other microbiological features of Streptococcus canis

This study assessed biofilm production ability (BPA) and other microbiological features of Streptococcus canis strains. Companion animal-origin 40 strains from each year (2015/2017) were randomly selected with the host information, and three blood-origin strains from 2 humans/1 dog were included. We measured BPA using crystal violet staining, along with S. canis M-like protein (SCM) allele typing, sequence type (ST) determination, antimicrobial resistance (AMR) phenotyping/genotyping, and virulence-associated gene profiling (gbp-ap1-fp1-brp). BPA measurements revealed that 35 strains with BPA and 48 strains without BPA. There was association of the producer with isolation year (2017). We found association between the non-producer and SCM allele 1/ST9: there was association of the producer with SCM allele 10/ST21. We observed correlation between the producer and presence of AMR genotypes. There was association between the producer and ap1 detection and between non-producer and gbp detection. Our observations suggest the correlation between the producer and other microbiological features (isolation year/SCM allele type 10/ST21/presence of AMR genotypes/ap1 detection).

Pathogenicity and drug resistance of animal streptococci responsible for human infections

Bacteria of the genus Streptococcus, earlier considered typically animal, currently have also been causing infections in humans. It is necessary to make clinicians aware of the emergence of new species that may cause the development of human diseases. There is an increasing frequency of isolation of streptococci such as S. suis, S. dysgalactiae, S. iniae and S. equi from people. Isolation of Streptococcus bovis/Streptococcus equinus complex bacteria has also been reported. The streptococcal species described in this review are gaining new properties and virulence factors by which they can thrive in new environments. It shows the potential of these bacteria to changes in the genome and the settlement of new hosts. Information is presented on clinical cases that concern streptococcus species belonging to the groups Bovis, Pyogenic and Suis. We also present the antibiotic resistance profiles of these bacteria. The emerging resistance to β-lactams has been reported. In this review, the classification, clinical characteristics and antibiotic resistance of groups and species of streptococci considered as animal pathogens are summarized.

Hair of the Dog? Periprosthetic Joint Infection with Streptococcus can is

A 61-year-old man underwent elective primary total hip arthroplasty at an academic center and presented to the emergency department 2 weeks later with a periprosthetic infection. Intraoperative cultures were positive for Streptococcus canis. He was successfully treated with one-stage revision and 6 weeks of intravenous cefazolin. It was later determined that the patient has a pet dog who frequently licks his legs. We hypothesize that patients with pets are more likely to carry this pathogen as part of their skin microbiome, and further research is required to establish whether S. canis poses an infectious risk beyond that of normal group B Streptococcus skin flora and if preoperative decolonization strategies are warranted.

An Outbreak of Subclinical Mastitis in a Dairy Herd Caused by a Novel Streptococcus canis Sequence Type (ST55)

Simple Summary

Although Streptococcus (S). canis is mainly isolated from carnivores, intramammary infection in dairy cows caused by this bacterium have been reported. Cats and dogs with access to the barn have been considered as the main source of these infections. Here, we report subclinical mastitis and substantially increased bulk milk somatic cell counts in a dairy herd. During a herd visit, management and hygiene practices were evaluated and data from the milk quality control program were retrieved. Furthermore, quarter milk samples, mucosal swabs from farm cats and a dog, and swabs from the milking unit were aseptically collected. The samples were examined bacteriologically, and S. canis was identified using conventional phenotypic methods and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Genetic relationships between S. canis isolates were determined by multilocus sequence typing, revealing that all S. canis isolates shared the same sequence type, presenting a new combination of alleles for which a new number (ST55) was assigned. As the most likely source of intramammary infection, a farmyard cat was identified. The concurrent treatment of all positive cows and the improvement of management (no further access of carnivores to the barn) lead to positive results, including a decreased somatic cell count.

Abstract

The present case report provides data on the phenotypic and genotypic properties of S. canis isolated from nine dairy cows with subclinical mastitis (SCC greater than 200,000 cells/mL in the quarter milk sample, no clinical signs) and from a cat living in the barn and reports the eradication of the pathogen from the herd with an automatic milking system. The isolates were identified using conventional bacteriology, matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) and genetic relationships were investigated by multilocus sequence typing (MLST). Udder health management and hygiene instructions comprised the removal of the carnivores from the barn, strict monitoring of milking hygiene and techniques to avoid new infections via the milking robot, with simultaneous therapy for all infected cows. Phenotypic and genotypic properties of all isolates were identical. MLST revealed a unique sequence type (ST55) and a farmyard cat was identified as the most likely source of the S. canis infection in cows. The simultaneous treatment of all infected cows and management and hygiene improvements lead to a decreased SCC within four weeks.

Streptococcal Infections in Marine Mammals

Marine mammals are sentinels for the marine ecosystem and threatened by numerous factors including infectious diseases. One of the most frequently isolated bacteria are beta-hemolytic streptococci. However, knowledge on ecology and epidemiology of streptococcal species in marine mammals is very limited. This review summarizes published reports on streptococcal species, which have been detected in marine mammals. Furthermore, we discuss streptococcal transmission between and adaptation to their marine mammalian hosts. We conclude that streptococci colonize and/or infect marine mammals very frequently, but in many cases, streptococci isolated from marine mammals have not been further identified. How these bacteria disseminate and adapt to their specific niches can only be speculated due to the lack of respective research. Considering the relevance of pathogenic streptococci for marine mammals as part of the marine ecosystem, it seems that they have been neglected and should receive scientific interest in the future.

Novel Models of Streptococcus canis Colonization and Disease Reveal Modest Contributions of M-Like (SCM) Protein

Streptococcus canis is a common colonizing bacterium of the urogenital tract of cats and dogs that can also cause invasive disease in these animal populations and in humans. Although the virulence mechanisms of S. canis are not well-characterized, an M-like protein, SCM, has recently identified been as a potential virulence factor. SCM is a surface-associated protein that binds to host plasminogen and IgGs suggesting its possible importance in host-pathogen interactions. In this study, we developed in vitro and ex vivo blood component models and murine models of S. canis vaginal colonization, systemic infection, and dermal infection to compare the virulence potential of the zoonotic S. canis vaginal isolate G361 and its isogenic SCM-deficient mutant (G361∆scm). We found that while S. canis establishes vaginal colonization and causes invasive disease in vivo, the contribution of the SCM protein to virulence phenotypes in these models is modest. We conclude that SCM is dispensable for invasive disease in murine models and for resistance to human blood components ex vivo, but may contribute to mucosal persistence, highlighting a potential contribution to the recently appreciated genetic diversity of SCM across strains and hosts.

Intracellular Invasion Ability and Associated Microbiological Characteristics of Streptococcus canis in Isolates from Japan

This study evaluated the cell invasion ability (CIA) of Streptococcus canis isolates, and clarified the relationship between high-frequency CIA and its microbiological features. Of the companion animal-origin isolates (n = 117) that were obtained in 2017, 40 isolates were randomly selected with the host information, with two human blood-origin isolates included. CIA was measured using human colon carcinoma epithelium and the hemolytic activity (HA) using sheep blood, along with S. canis M-like protein (SCM) allele typing, sequence type (ST) determination, and antimicrobial resistance (AMR) phenotyping/genotyping. CIA measurements revealed that 19 and 24 isolates had high- and low-frequencies, respectively. HA assessment revealed that 24 and 19 isolates were categorized as high- and low- level, respectively. No difference was observed in the high-/low-level HA between the high- /low-frequency CIA populations. A significant difference was found in the high-/low-frequency CIA between the SCM group I/II populations. Additionally, a significantly higher CIA was found in the SCM allele type 10/type 11 than in the others. A significant association was observed between high-frequency CIA and the ST21/ST41 populations. No difference was found in the high-/low-frequency CIA between the presence and absence of the AMR phenotype/genotype. These observations suggest a relationship between high-frequency CIA and its microbiological characteristics (SCM allele type 10/type 11 or ST21/ST41).

Novel Quinolone Nonsusceptible Streptococcus canis Strains with Point Mutations in Quinolone Resistance-Determining Regions and Their Related Factors

This study investigated quinolone nonsusceptible Streptococcus canis with point mutations in quinolone resistance-determining regions (QRDRs). After selecting targets from 185 isolates, we tested antimicrobial susceptibility using levofloxacin, ciprofloxacin, norfloxacin, and moxifloxacin. We also determined the amino acid sequences of QRDRs in gyrA/gyrB/parC/parE genes and their point mutations. Finally, we performed S. canis-derived M-like protein (SCM) allele typing, multilocus sequence typing, and antimicrobial resistance genotyping. Correlations between nonsusceptible strains and their related factors were examined. We found 13 (7.0%) nonsusceptible isolates consisting of two classes, high-level minimum inhibitory concentrations (MICs) (n = 7, 3.8%) and low-level MICs (n = 6, 3.2%). Mutations Ser81Phe/Ser81Tyr/Glu85Lys in gyrA, Ser67Phe/Ser67Tyr/Asp71Tyr in parC, Asp438Asn in parE, and Gly408Asp in gyrB were observed in these nonsusceptible strains. Common mutations included Ser81 and Ser67/Asp71; additionally, we found one strain each with Glu85, Asp438, and Gly408 mutations. There was a significant correlation between nonsusceptible isolates and the presence of SCM allele type 2, sequence type 46, tetracyclineresistance genes, and macrolide/lincosamide-resistance genes. These results could be used in future, by veterinarians while treating companion animals with clinical symptoms of streptococcal infections.

One Health and Streptococcus Canis in the Emergency Department: A Case of Cellulitis and Bacteremia in an Immunocompromised Patient Treated With Etanercept

BACKGROUND

One Health is a biomedical approach that aims to optimize the health of humans, animals, and the environment through interdisciplinary collaboration. Cellulitis is an infection of the dermis and subcutaneous fat that may be caused by zoonotic streptococci species.

CASE REPORT

We report a case of cellulitis caused by Streptococcus canis in a woman who was taking Etanercept. We frame the presentation within a One Health approach and urge emergency physicians to collaborate with veterinarians in the management of patients with zoonotic diseases who are discharged home. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Pets are a source for zoonotic diseases, including resistant bacteria, that pose particular risk to immunocompromised patients. Emergency physicians often discharge patients with potential zoonotic infections such as cellulitis home without a long-term, holistic care plan, according to a One Health approach. Physicians should then collaborate with veterinarians in caring for humans and animals.

Streptococcus canis multilocus sequence typing in a case series of dogs with ulcerative keratitis

OBJECTIVE

To determine whether four isolates of Streptococcus canis (S canis) recovered from dogs diagnosed with ulcerative keratitis at the Animal Health Trust (AHT) were genetically related to other ocular isolates that are registered in the online database.

ANIMAL STUDIED

Four S canis corneal isolates.

PROCEDURES

Clinical and laboratory records between 2016 and 2017 were searched for dogs with ulcerative keratitis for which microbiology analysis was consistent with the growth of S canis. Genomic DNA was extracted for sequencing (Illumina MiSeq), and multilocus sequence types (STs) were determined using MLST 1.8 relative to the 44 sequence types of S canis available. A neighbor-joining tree was constructed in MEGA v4.0. A two-sided Fisher's exact test was used to determine any associations between the isolated strains and ocular infections of dogs.

RESULTS

Four strains were isolated from pugs (cases 1-4) with ulcerative keratitis. Genome sequencing identified ST-27 (case 1), ST-9 (case 3), and ST-13 (cases 2 and 4). STs 13 and 27 are members of Clonal Complex (CC)-13. Analysis of the multilocus sequence typing database revealed that CC-13 strains accounted for six of the twelve isolates recovered from the eye exudates of dogs (P = .0078).

CONCLUSIONS

There is early evidence that the CC-13 group of S canis is associated with ocular infections in dogs. We provide draft genome sequences toward the future identification of virulence mechanisms associated with streptococcal keratitis in dogs.

Pathogenicity Factors in Group C and G Streptococci

Initially recognized zoonoses, streptococci belonging to Lancefield group C (GCS) and G (GGS) were subsequently recognised as human pathogens causing a diverse range of symptoms, from asymptomatic carriage to life threatening diseases. Their taxonomy has changed during the last decade. Asymptomatic carriage is <4% amongst the human population and invasive infections are often in association with chronic diseases such as diabetes, cardiovascular diseases or chronic skin infections. Other clinical manifestations include acute pharyngitis, pneumonia, endocarditis, bacteraemia and toxic-shock syndrome. Post streptococcal sequalae such as rheumatic fever and acute glomerulonephritis have also been described but mainly in developed countries and amongst specific populations. Putative virulence determinants for these organisms include adhesins, toxins, and other factors that are essential for dissemination in human tissues and for interference with the host immune responses. High nucleotide similarities among virulence genes and their association with mobile genetic elements supports the hypothesis of extensive horizontal gene transfer events between the various pyogenic streptococcal species belonging to Lancefield groups A, C and G. A better understanding of the mechanisms of pathogenesis should be apparent by whole-genome sequencing, and this would result in more effective clinical strategies for the pyogenic group in general.

Homophilic protein interactions facilitate bacterial aggregation and IgG-dependent complex formation by the Streptococcus canis M protein SCM

Streptococcus canis is a zoonotic agent that causes serious invasive diseases in domestic animals and humans, but knowledge about its pathogenic potential and underlying virulence mechanisms is limited. Here, we report on the ability of certain S. canis isolates to form large bacterial aggregates when grown in liquid broth. Bacterial aggregation was attributed to the presence and the self-binding activity of SCM, the M protein of S. canis, as evaluated by bacterial sedimentation assays, immunofluorescence- and electron microscopic approaches. Using a variety of truncated recombinant SCM fragments, we demonstrated that homophilic SCM interactions occur via the N-terminal, but not the C-terminal part, of the mature M protein. Interestingly, when incubated in human plasma, SCM forms soluble protein complexes comprising its known ligands, immunoglobulin G (IgG) and plasminogen (Plg). Co-incubation studies with purified host proteins revealed that SCM-mediated complex formation is based on the interaction of SCM with itself and with IgG, but not with Plg or fibrinogen (Fbg), well-established constituents of M protein-mediated protein complexes in human-associated streptococci. Notably, these soluble, SCM-mediated plasma complexes harbored complement factor C1q, which can induce complement breakdown in the periphery and therefore represent another immune evasion mechanism of SCM.

Characterization, mechanism of action and optimization of activity of a novel peptide-peptoid hybrid against bacterial pathogens involved in canine skin infections

Integumentary infections like pyoderma represent the main reason for antimicrobial prescription in dogs. Staphylococcus pseudintermedius and Pseudomonas aeruginosa are frequently identified in these infections, and both bacteria are challenging to combat due to resistance. To avoid use of important human antibiotics for treatment of animal infections there is a pressing need for novel narrow-spectrum antimicrobial agents in veterinary medicine. Herein, we characterize the in vitro activity of the novel peptide-peptoid hybrid B1 against canine isolates of S. pseudintermedius and P. aeruginosa. B1 showed potent minimum inhibitory concentrations (MICs) against canine S. pseudintermedius and P. aeruginosa isolates as well rapid killing kinetics. B1 was found to disrupt the membrane integrity and affect cell-wall synthesis in methicillin-resistant S. pseudintermedius (MRSP). We generated 28 analogues of B1, showing comparable haemolysis and MICs against MRSP and P. aeruginosa. The most active analogues (23, 26) and B1 were tested against a collection of clinical isolates from canine, of which only B1 showed potent activity. Our best compound 26, displayed activity against P. aeruginosa and S. pseudintermedius, but not the closely related S. aureus. This work shows that design of target-specific veterinary antimicrobial agents is possible, even species within a genus, and deserves further exploration.

Human native endocarditis caused by Streptococcus canis-a case report

We report a very rare case of Streptococcus canis native infective endocarditis in a 73-year-old woman living in close contact with her dog. Her echocardiography showed large calcifications in the mitral annulus, massive regurgitation below the posterior leaflet, and adjacent vegetation. Blood culture was positive for Streptococcus Lancefield group G. A coronary artery bypass and mitral valve replacement had to be done. Streptococcus canis was detected in a heart valve using a broad range PCR followed by 16S rRNA and confirmed by tuf gene sequencing, while tissue culture remained negative. The patient was not bitten by her dog nor did she have comorbidities or skin ulcers. She fully recovered.

Prevalence and diversity of M-like protein (SCM) gene in Streptococcus canis isolates from diseased companion animals in Japan: Implication of SCM allele

Streptococcus canis (Sc)-origin M-like protein (SCM) binds to plasminogen and immunoglobulin G and facilitates anti-phagocytic properties. We aimed to determine the prevalence and diversity of the scm gene in Sc isolates from diseased companion animals in Japan and to propose potential SCM alleles of amino acid (AA) sequences. We collected β-hemolytic streptococci from diseased animals with host information nationwide in 2015 and 2017. After Sc identification and scm gene amplification and sequencing, the gene's prevalence and relationship between its presence and host information were determined. Furthermore, phylogenetic trees of AA sequences were constructed, and classification and distribution of SCM alleles based on variations of AA sequences were conducted. The scm detection rates were 70.6% (n = 48, 2015) and 82.9% (n = 97, 2017). There was a relationship between scm presence and Tokyo in 2015 and 2017. We found an association between scm detection and dogs in 2017 alone. Major sequence sizes were 1311 bp, 1308 bp, and 1305 bp. Using the phylogenetic trees of AA sequences, we confirmed shared positions of five identical sequence patterns in both periods. Nine SCM alleles were determined with six signal-peptide types. Most prevalent alleles were type 1, type 2, and type 4 in both periods. Our observations suggest prevalence and diversity of scm in animal-origin Sc isolates in Japan.

Draft Genome Sequence of Streptococcus canis Clinical Strain TA4, Harboring the M-Like Protein Gene and Isolated in Japan from a Patient with Bacteremia

Streptococcus canis is an animal-origin β-hemolytic bacterium that can cause severe infections in animals and occasionally infects humans. Here, we report a draft genome sequence of an S. canis strain harboring the M-like protein gene. This strain was isolated from a patient with bacteremia (reported by Taniyama et al. [D. Taniyama, Y. Abe, T. Sakai, T. Kikuchi, and T. Takahashi, IDCases 7:48–52, 2017, https://doi.org/10.1016/j.idcr.2017.01.002]). The draft genome comprises 2,129,080 bp in 60 contigs.

Draft Genome Sequence of Zoonotic Streptococcus canis Isolate G361

Here, we report the draft genome sequence of an SCM-positive Streptococcus canis strain, G361, isolated from a vaginal swab of a 40-year-old woman. The draft genome comprises 2,045,931 bp in 62 contigs.

SCM, the M Protein of Streptococcus canis Binds Immunoglobulin G

The M protein of Streptococcus canis (SCM) is a virulence factor and serves as a surface-associated receptor with a particular affinity for mini-plasminogen, a cleavage product of the broad-spectrum serine protease plasmin. Here, we report that SCM has an additional high-affinity immunoglobulin G (IgG) binding activity. The ability of a particular S. canis isolate to bind to IgG significantly correlates with a scm-positive phenotype, suggesting a dominant role of SCM as an IgG receptor. Subsequent heterologous expression of SCM in non-IgG binding S. gordonii and Western Blot analysis with purified recombinant SCM proteins confirmed its IgG receptor function. As expected for a zoonotic agent, the SCM-IgG interaction is species-unspecific, with a particular affinity of SCM for IgGs derived from human, cats, dogs, horses, mice, and rabbits, but not from cows and goats. Similar to other streptococcal IgG-binding proteins, the interaction between SCM and IgG occurs via the conserved Fc domain and is, therefore, non-opsonic. Interestingly, the interaction between SCM and IgG-Fc on the bacterial surface specifically prevents opsonization by C1q, which might constitute another anti-phagocytic mechanism of SCM. Extensive binding analyses with a variety of different truncated SCM fragments defined a region of 52 amino acids located in the central part of the mature SCM protein which is important for IgG binding. This binding region is highly conserved among SCM proteins derived from different S. canis isolates but differs significantly from IgG-Fc receptors of S. pyogenes and S. dysgalactiae sub. equisimilis, respectively. In summary, we present an additional role of SCM in the pathogen-host interaction of S. canis. The detailed analysis of the SCM-IgG interaction should contribute to a better understanding of the complex roles of M proteins in streptococcal pathogenesis.

Human case of bacteremia caused by Streptococcus canis sequence type 9 harboring the scm gene

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This is the first reported human case of bacteremia caused by Streptococcus canis having scm gene encoding M-like protein.

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The identity was based on similarity of its 16S rRNA and detection of the specific cfg gene encoding a co-hemolysin.

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This isolate was confirmed to be sequence type 9.

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This strain didn’t have the erm(A), erm(B), or mef(A), macrolide resistance genes, but was not susceptible to azithromycin.

Streptococcus canis (Sc) is a zoonotic pathogen that is transferred mainly from companion animals to humans. One of the major virulence factors in Sc is the M-like protein encoded by the scm gene, which is involved in anti-phagocytic activities, as well as the recruitment of plasminogen to the bacterial surface in cooperation with enolase, and the consequent enhancement of bacterial transmigration and survival. This is the first reported human case of uncomplicated bacteremia following a dog bite, caused by Streptococcus canis harboring the scm gene. The similarity of the 16S rRNA from the infecting species to that of the Sc type strain, as well as the amplification of the species-specific cfg gene, encoding a co-hemolysin, was used to confirm the species identity. Furthermore, the isolate was confirmed as sequence type 9. The partial scm gene sequence harbored by the isolate was closely related to those of other two Sc strains. While this isolate did not possess the erm(A), erm(B), or mef(A), macrolide/lincosamide resistance genes, it was not susceptible to azithromycin: its susceptibility was intermediate. Even though human Sc bacteremia is rare, clinicians should be aware of this microorganism, as well as Pasteurella sp., Prevotella sp., and Capnocytophaga sp., when examining and treating patients with fever who maintain close contact with companion animals.

First case of a dog bite wound infection caused by Streptococcus minor in human

We report the first case of human infection caused by Streptococcus minor in a 51-year-old immunocompetent woman admitted for dog bite injuries. At present, the role of Streptococcus minor in bite wound infections is unknown. Further studies on virulence factors are needed to elucidate its pathogenicity mechanisms.

Recurrent bacteremia with Streptococcus dysgalactiae: a case-control study

Beta-hemolytic streptococci of groups C and G, designated as Streptococcus dysgalactiae (SD), can cause severe and recurring invasive infections. In this case-control study, we aimed to identify clinical and molecular risk factors for recurrence of SD bacteremia. Twenty-two cases of recurrent SD bacteremia were identified, and median time between episodes was 6 months. The most frequent clinical manifestation was skin and soft tissue infection. Cases and 92 controls, with single-episode SD bacteremia, showed similar demographics, had similar Charlson comorbidity scores, and had similar clinical presentations. Thirty-day fatality was 13% among controls, whereas none of 22 cases died. In 19 cases (86%), the same emm type was encountered in both episodes. SD isolates from recurrent episodes and from single episodes had a similar emm type distribution. Thus, we did not identify clinical risk factors for recurrences. The high proportion of identical emm types in recurrent episodes indicates a host-specific colonization.

Endocarditis caused by Streptococcus canis: an emerging zoonosis?

We report a human case of infective endocarditis caused by Streptococcus canis. Identification was carried out from positive blood culture using mass spectrometry and SodA gene sequencing. S. canis related zoonotic invasive infections may have been previously underdiagnosed due to inadequate identification of group G Streptococcus species.

Horizontal gene transfer and recombination in Streptococcus dysgalactiae subsp. equisimilis

Streptococcus dysgalactiae subsp. equisimilis (SDSE) is a human pathogen that colonizes the skin or throat, and causes a range of diseases from relatively benign pharyngitis to potentially fatal invasive diseases. While not as virulent as the close relative Streptococcus pyogenes the two share a number of virulence factors and are known to coexist in a human host. Both pre- and post-genomic studies have revealed that horizontal gene transfer (HGT) and recombination occurs between these two organisms and plays a major role in shaping the population structure of SDSE. This review summarizes our current knowledge of HGT and recombination in the evolution of SDSE.

Multilocus sequence analysis of Streptococcus canis confirms the zoonotic origin of human infections and reveals genetic exchange with Streptococcus dysgalactiae subsp. equisimilis

Streptococcus canis is an animal pathogen that occasionally causes human infections. Isolates recovered from infections of animals (n = 78, recovered from 2000 to 2010 in three European countries, mainly from house pets) and humans (n = 7, recovered from 2006 to 2010 in Portugal) were identified by phenotypic and genotypic methods and characterized by antimicrobial susceptibility testing, multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and emm typing. S. canis isolates presented considerable variability in biochemical profiles and 16S rRNA. Resistance to antimicrobial agents was low, with the most significant being tet(M)- and tet(O)-mediated tetracycline resistance. MLST analysis revealed a polyclonal structure of the S. canis population causing infections, where the same genetic lineages were found infecting house pets and humans and were disseminated in distinct geographic locations. Phylogenetic analysis indicated that S. canis was a divergent taxon of the sister species Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis and found evidence of acquisition of genetic material by S. canis from S. dysgalactiae subsp. equisimilis. PFGE confirmed the MLST findings, further strengthening the similarity between animal and human isolates. The presence of emm-like genes was restricted to a few isolates and correlated with some MLST-based genetic lineages, but none of the human isolates could be emm typed. Our data show that S. canis isolates recovered from house pets and humans constitute a single population and demonstrate that isolates belonging to the main genetic lineages identified have the ability to infect the human host, providing strong evidence for the zoonotic nature of S. canis infection.

Genome characterization and population genetic structure of the zoonotic pathogen, Streptococcus canis

Background

Streptococcus canis is an important opportunistic pathogen of dogs and cats that can also infect a wide range of additional mammals including cows where it can cause mastitis. It is also an emerging human pathogen.

Results

Here we provide characterization of the first genome sequence for this species, strain FSL S3-227 (milk isolate from a cow with an intra-mammary infection). A diverse array of putative virulence factors was encoded by the S. canis FSL S3-227 genome. Approximately 75% of these gene sequences were homologous to known Streptococcal virulence factors involved in invasion, evasion, and colonization. Present in the genome are multiple potentially mobile genetic elements (MGEs) [plasmid, phage, integrative conjugative element (ICE)] and comparison to other species provided convincing evidence for lateral gene transfer (LGT) between S. canis and two additional bovine mastitis causing pathogens (Streptococcus agalactiae, and Streptococcus dysgalactiae subsp. dysgalactiae), with this transfer possibly contributing to host adaptation. Population structure among isolates obtained from Europe and USA [bovine = 56, canine = 26, and feline = 1] was explored. Ribotyping of all isolates and multi locus sequence typing (MLST) of a subset of the isolates (n = 45) detected significant differentiation between bovine and canine isolates (Fisher exact test: P = 0.0000 [ribotypes], P = 0.0030 [sequence types]), suggesting possible host adaptation of some genotypes. Concurrently, the ancestral clonal complex (54% of isolates) occurred in many tissue types, all hosts, and all geographic locations suggesting the possibility of a wide and diverse niche.

Conclusion

This study provides evidence highlighting the importance of LGT in the evolution of the bacteria S. canis, specifically, its possible role in host adaptation and acquisition of virulence factors. Furthermore, recent LGT detected between S. canis and human bacteria (Streptococcus urinalis) is cause for concern, as it highlights the possibility for continued acquisition of human virulence factors for this emerging zoonotic pathogen.

Human pathogenic streptococcal proteomics and vaccine development

Gram-positive streptococci are non-motile, chain-forming bacteria commonly found in the normal oral and bowel flora of warm-blooded animals. Over the past decade, a proteomic approach combining 2-DE and MS has been used to systematically map the cellular, surface-associated and secreted proteins of human pathogenic streptococcal species. The public availability of complete streptococcal genomic sequences and the amalgamation of proteomic, genomic and bioinformatic technologies have recently facilitated the identification of novel streptococcal vaccine candidate antigens and therapeutic agents. The objective of this review is to examine the constituents of the streptococcal cell wall and secreted proteome, the mechanisms of transport of surface and secreted proteins, and describe the current methodologies employed for the identification of novel surface-displayed proteins and potential vaccine antigens.

Gene repertoire evolution of Streptococcus pyogenes inferred from phylogenomic analysis with Streptococcus canis and Streptococcus dysgalactiae

Streptococcus pyogenes, is an important human pathogen classified within the pyogenic group of streptococci, exclusively adapted to the human host. Our goal was to employ a comparative evolutionary approach to better understand the genomic events concomitant with S. pyogenes human adaptation. As part of ascertaining these events, we sequenced the genome of one of the potential sister species, the agricultural pathogen S. canis, and combined it in a comparative genomics reconciliation analysis with two other closely related species, Streptococcus dysgalactiae and Streptococcus equi, to determine the genes that were gained and lost during S. pyogenes evolution. Genome wide phylogenetic analyses involving 15 Streptococcus species provided convincing support for a clade of S. equi, S. pyogenes, S. dysgalactiae, and S. canis and suggested that the most likely S. pyogenes sister species was S. dysgalactiae. The reconciliation analysis identified 113 genes that were gained on the lineage leading to S. pyogenes. Almost half (46%) of these gained genes were phage associated and 14 showed significant matches to experimentally verified bacteria virulence factors. Subsequent to the origin of S. pyogenes, over half of the phage associated genes were involved in 90 different LGT events, mostly involving different strains of S. pyogenes, but with a high proportion involving the horse specific pathogen S. equi subsp. equi, with the directionality almost exclusively (86%) in the S. pyogenes to S. equi direction. Streptococcus agalactiae appears to have played an important role in the evolution of S. pyogenes with a high proportion of LGTs originating from this species. Overall the analysis suggests that S. pyogenes adaptation to the human host was achieved in part by (i) the integration of new virulence factors (e.g. speB, and the sal locus) and (ii) the construction of new regulation networks (e.g. rgg, and to some extent speB).

Epidemiology and pathogenicity of zoonotic streptococci

Zoonotic infections caused by Streptococcus spp. have been neglected in spite of the fact that frequency and severity of outbreaks increased dramatically in recent years. This may be due to non-identification since respective species are often not considered in human medical diagnostic procedures. On the other hand, an expanding human population concomitant with an increasing demand for food and the increased number of companion animals favour conditions for host species adaptation of animal streptococci. This review aims to give an overview on streptococcal zoonoses with focus on epidemiology and pathogenicity of four major zoonotic species, Streptococcus canis, Streptococcus equi sub. zooepidemicus, Streptococcus iniae and Streptococcus suis.