Distribution of Capnocytophaga canimorsus in dogs and cats with genetic characterization of isolates

Emergence of Capnocytophaga canimorsus and Capnocytophaga cynodegmi in oral cavities of newborn puppies, a pilot study

Capnocytophaga canimorsus and Capnocytophaga cynodegmi are commensal bacteria in the oral cavities of dogs. Both are zoonotic pathogens that could infect humans via dog bites. C. canimorsus may cause life-threatening infections in humans, whereas C. cynodegmi infections tend to be milder and more localized. Capsular serovars A-C of C. canimorsus seem to be virulence-associated. Some of the C. canimorsus serovars described to date can also be detected in other Capnocytophaga species, including C. cynodegmi. The objective of this pilot study was to investigate the emergence of C. canimorsus and C. cynodegmi after birth in oral cavities of puppies and to evaluate the impact of the dam's Capnocytophaga spp. carrier status on the emergence. Ten litters, altogether 59 puppies, were included in the study. The puppies and their dams were sampled at five time points over seven weeks after whelping. Oral swab samples taken were investigated for the presence of C. canimorsus and C. cynodegmi by species-specific polymerase chain reaction (PCR), the specificity of which was verified by sequencing a selection of the PCR products. Samples that were positive in Capnocytophaga PCR reactions were also capsular-typed by PCR to gain more knowledge about the Capnocytophaga spp. present in the samples. Altogether 10.2% and 11.9% of puppies, or 20.0% and 30.0% of litters tested PCR-positive for C. canimorsus and C. cynodegmi, respectively. Capnocytophaga PCR-positive puppy samples were always positive for only C. cynodegmi or C. canimorsus, not both. Most Capnocytophaga PCR-positive puppies became positive at the age of 5 to 7 weeks. Only a minority (5/16) of the C. cynodegmi PCR-positive dog samples were positive in capsular typing PCR, whereas all C. canimorsus PCR-positive dog samples were negative in capsular typing PCR. For all Capnocytophaga PCR-positive puppies, their dam was positive for the same Capnocytophaga species. These results suggest that puppies become colonized by C. cynodegmi or C. canimorsus from their dams at the time of deciduous teeth eruption.

Furry, Fomite, and Facultative Anaerobe: A Unique Case of Capnocytophaga canimorsus

Capnocytophaga canimorsus infection is frequently associated with dog and cat bites or scratches in patients who have risk factors such as immunosuppression, asplenia, and alcohol abuse. However, rare instances of C. canimorsus infection in patients without typical risk factors have been reported. Here, we present such a rare and unusual case of C. canimorsus bacteremia in a patient without animal wounds or risk factors. Chronic sinusitis may have contributed to mucosal disruption and served as an entry point for C. canimorsus. Prompt initiation of antibiotics resulted in rapid resolution of symptoms and clearance of bacteremia.

A Novel 16S rRNA PCR-Restriction Fragment Length Polymorphism Assay to Accurately Distinguish Zoonotic Capnocytophaga canimorsus and C. cynodegmi

The zoonotic bacteria Capnocytophaga canimorsus and C. cynodegmi, the predominant Capnocytophaga species in the canine oral biota, can cause human local wound infections or lethal sepsis, usually transmitted through dog bites. Molecular surveying of these Capnocytophaga species using conventional 16S rRNA-based PCR is not always accurate due to their high genetic homogeneity. In this study, we isolated Capnocytophaga spp. from the canine oral cavity and identified them using 16S rRNA and phylogenetic analysis. A novel 16S rRNA PCR-restriction fragment length polymorphism (RFLP) method was designed based on our isolates and validated using published C. canimorsus and C. cynodegmi 16S rRNA sequences. The results showed that 51% of dogs carried Capnocytophaga spp. Among these, C. cynodegmi (47/98, 48%) was the predominant isolated species along with one strain of C. canimorsus (1/98, 1%). Alignment analysis of 16S rRNA sequences revealed specific site nucleotide diversity in 23% (11/47) of the C. cynodegmi isolates, which were misidentified as C. canimorsus using previously reported species-specific PCR. Four RFLP types could be classified from all the isolated Capnocytophaga strains. The proposed method demonstrates superior resolution in distinguishing C. cynodegmi (with site-specific polymorphism) from C. canimorsus and especially in distinguishing C. canimorsus from other Capnocytophaga species. After in silico validation, this method was revealed to have an overall detection accuracy of 84%; notably, accuracy reached 100% in C. canimorsus strains isolated from human patients. Overall, the proposed method is a useful molecular tool for the epidemiological study of Capnocytophaga in small animals and for the rapid diagnosis of human C. canimorsus infections. IMPORTANCE With the increased number of small animal breeding populations, zoonotic infections associated with small animals need to be taken more seriously. Capnocytophaga canimorsus and C. cynodegmi are part of common biota in the mouths of small animals and can cause human infections through bites or scratches. In this study, C. cynodegmi with site-specific 16S rRNA sequence polymorphisms was erroneously identified as C. canimorsus during the investigation of canine Capnocytophaga by conventional PCR. Consequently, the prevalence of C. canimorsus is incorrectly overestimated in epidemiological studies in small animals. We designed a new 16S rRNA PCR-RFLP method to accurately distinguish zoonotic C. canimorsus from C. cynodegmi. After validation against published Capnocytophaga strains, this novel molecular method had high accuracy and could detect 100% of C. canimorsus-strain infections in humans. This novel method can be used for epidemiological studies and the diagnosis of human Capnocytophaga infection following exposure to small animals.

Culture-negative Capnocytophaga canimorsus meningitis diagnosed by 16s ribosomal RNA polymerase chain reaction in an immunocompetent veterinarian and a review of the literature

Capnocytophaga canimorsus is a fastidious, capnophilic and facultative anaerobic Gram-negative rod found commonly in the oral flora of dogs that may cause zoonotic infections such as cellulitis and eye infections. In immunocompromised patients, it may cause fulminant sepsis. Meningitis due to C. canimorsus is, however, a rare manifestation. This is the first reported case of C. canimorsus meningitis in Australia in an immunocompetent veterinarian diagnosed by 16s ribosomal RNA polymerase chain reaction.

Influence of the dental topical application of a nisin-biogel in the oral microbiome of dogs: a pilot study

Periodontal disease (PD) is one of the most widespread inflammatory diseases in dogs. This disease is initiated by a polymicrobial biofilm in the teeth surface (dental plaque), leading to a local inflammatory response, with gingivitis and/or several degrees of periodontitis. For instance, the prevention of bacterial dental plaque formation and its removal are essential steps in PD control. Recent research revealed that the antimicrobial peptide nisin incorporated in the delivery system guar gum (biogel) can inhibit and eradicate bacteria from canine dental plaque, being a promising compound for prevention of PD onset in dogs. However, no information is available regarding its effect on the dog’s oral microbiome. In this pilot study, the influence of the nisin-biogel on the diversity of canine oral microbiome was evaluated using next generation sequencing (NGS), aiming to access the viability of nisin-biogel to be used in long-term experiment in dogs. Composite toothbrushing samples of the supragingival plaque from two dogs were collected at three timepoints: T1—before any application of the nisin-biogel to the animals’ teeth surface; T2—one hour after one application of the nisin-biogel; and T3—one hour after a total of three applications of the nisin-biogel, each 48 hours. After that, microbial profiling was performed by NGS of the V3V4 16s rRNA region. After only one application of the nisin-biogel to the oral cavity of dogs, a statistically significant reduction in microbial diversity was observed (T2) as well as a reduction of some bacterial species potentially related with distinct stages of PD, when compared with samples collected before any application (T1). However, after a total of three nisin-biogel applications (T3), a recovery of the microbial diversity was detected. In conclusion, the nisin-biogel may influence the canine oral microbiome. A reduction in some bacterial species potentially related with distinct stages of PD was observed. This pilot study will help to design a controlled in vivo clinical trial to evaluate nisin-biogel effect on dental plaque progression and canine periodontal indices evolution in a long-term application period.

Health Status of 'Community Cats' Living in the Tourist Area of the Old Town in Onomichi City, Japan

The "community cat program (CCP)" is a non-lethal control measure in which stray cats are owned and cared for as community cats at high welfare standards, while the Trap-Neuter-Return (TNR) or Trap-Test-Vaccinate-Alter-Return-Monitor (TTVARM) event is performed. The program is recommended by the Ministry of the Environment in Japan. Here, we evaluated the health status of community cats inhabiting a tourist area in Onomichi City. A medical check was conducted on 30 community cats as a part of the TTVARM event. The following health problems were identified: alopecia, gingivitis, incisor teeth loss, anemia, and urine glucose. An ELISA (the enzyme linked immunosorbent assay) showed that 16.7% of the cats were FIV-positive. The cats were also carriers of zoonoses (Capnocytophaga genus (100%) and Bartonella henselae (ITS, nested; 38.0%)), which pose a risk to tourists and residents. Our findings suggest that most cats require medical treatment. We recommend that friendly cats should be adopted rather than maintained as community cats and that a comprehensive review of the CCP is required.

Capnocytophaga felis sp. nov. isolated from the feline oral cavity

Four strains, KC07070^T, KC07105, 11 025B-8C and 11 026B-8-C, were isolated from the oral cavity of cats in 2007 or 2011 in Japan. These strains were Gram-stain-negative rods, exhibited gliding motility, grew in air with 5 % CO₂ and showed catalase and oxidase activity. The sequences of 16S rRNA genes of the four strains were 100 % identical. Additionally, the sequences of 16S rRNA genes of KC07070^T had identity to those of the type strains of Capnocytophaga canimorsus (97.7 %), Capnocytophaga cynodegmi (97.8 %) and Capnocytophaga canis (97.4 %) and 91.2-93.8% identity to those of other species of the genus Capnocytophaga. The major cellular fatty acids of KC07070^T were iso-C_15 : 0 (56.2 %) and summed feature 11 (14.9 %). The G+C content of the DNA from KC07070^T was 35.6 mol%, and the genome size was 2.88 Mbp. KC07070^T had digital DNA-DNA hybridization (dDDH) values of 26.2-27.6% and average nucleotide identity (ANI) values of 75.4-83.3 % to the type strains of the closest relatives, C. canimorsus, C. cynodegmi and C. canis. These results of phylogenetic analysis of 16S rRNA gene sequence, cellular fatty acids compositions and dDDH and ANI values indicate that strain KC07070^T represents a novel species, for which we propose the name Capnocytophaga felis sp. nov., with type strain KC07070^T (=JCM 32681^T=DSM 107251^T).

A case of fulminant sepsis caused by Capnocytophaga canimorsus after a dog bite

Many species of microorganisms of various human pathogenicity have been identified in the oral cavities of dogs and cats. One of them is Capnocytophaga canimorsus, a Gram-negative bacterium of the Flavobacteriacae family, with unique abilities to forage sugars from host tissues and avoid the host immune response. Although C. canimorsus may be isolated from the oral cavities of most dogs and cats, severe human infection is very rare according to studies (0.67 cases/million/year). A canine or feline bite is the most common source of infection. At the highest risk are asplenic or functionally asplenic patients as well as individuals with cirrhosis or a history of alcohol abuse. We report a fatal case of C. canimorsus sepsis in a patient with a spleen.

Unexpected pathogen presenting with purulent meningitis

Herein we report a case of a 67-year-old man with chronic lymphocytic leukaemia who developed acute onset of fever and altered mental status while receiving ibrutinib therapy. He was eventually found to have Capnocytophaga canimorsus meningitis. Timely diagnosis and appropriate antimicrobial therapy was associated with a favourable outcome. We describe challenges associated with appropriate identification of, and briefly review infections caused by Capnocytophaga sp. To our knowledge, this is the first case of invasive C. canimorsus infection in the setting of ibrutinib therapy, and adds to the growing list of serious infections that have been associated with this agent.

A rare case of purulent meningitis caused by Capnocytophaga canimorsus in the Czech Republic - case report and review of the literature

Background

Invasive infections caused by Capnocytophaga canimorsus are rare. Immunocompromised patients, who report being bitten by or having a close contact with an animal, represent a high-risk group for this infection. There are only few dozens of infections by this bacteria manifesting as purulent meningitis reported worldwide. The reported case is a first reported case of purulent meningitis caused by by Capnocytophaga canimorsus in Czech Republic with only a limited risk factor history.

Case presentation

The patient, a 74 years old man, was referred to the infectious diseases department of a teaching hospital with clear signs of developing purulent meningitis. His anamnestic data did not show any unusual findings. He was treated for compensated diabetes mellitus type II. The blood cultures were negative and the etiological agent did not grow from the cerebrospinal fluid (CSF) on common media. Eventually, it was identified by detecting pan-bacterial DNA and DNA sequencing. Subsequently, the pathogen was confirmed by anaerobic cultivation from CSF. Only after then the patient recalled being bitten by his German shepherd puppy during play. The patient was successfully treated intravenously by ceftriaxone.

Conclusions

Purulent meningitis caused by Capnocytophaga spp. is a rare disease, but it needs to be considered in patients at risk with pre-existing conditions, who report close contact with or being bitten by an animal. It is important to test for this microbe in cases with negative microbiological results for the more common agents.

Capnocytophaga canimorsus Periprosthetic Joint Infection in an Immunocompetent Patient: A Case Report

Introduction:

A periprosthetic joint infection (PJI) is a potentially devastating complication following an arthroplasty procedure. There are many organisms that commonly cause this complication; in this case report, we will discuss a PJI caused by an unusual bacteria found in the mouths of domestic pets.

Objective:

To present a case report of a patient with a periprosthetic hip infection from Capnocytophaga canimorsus and review the literature.

Methods:

We present a case of C canimorsus PJI in an immunocompetent woman who had undergone a total hip arthroplasty. The patient was doing well postoperatively for many years until she was bitten on the foot by a domestic canine. Patient diagnosed using Musculoskeletal Infection Society criteria, then treated with explant of the hip prosthesis, irrigation and debridement, placement of an antibiotic cement spacer, and a 6-week course of intravenous antibiotics.

Results:

Unfortunately, while awaiting replant, this patient had a massive myocardial infarction and died.

Discussion:

Current literature suggests treating canine bites with amoxicillinas well as a discussion with patients pre-/postoperatively from a lower extremity arthroplasty specialist.

Conclusion:

Capnocytophaga canimorsus is a rare cause of infection, even more unusual in an immunocompetent patient. This study highlights the importance of considering C canimorsus as a cause of PJI, regardless of the immunologic status of the patient.

Capnocytophaga keratitis in dogs: clinical, histopathologic, and microbiologic features of seven cases

OBJECTIVE

To describe the clinical, microbiologic, and histopathologic features of Capnocytophaga keratitis in dogs.

ANIMALS STUDIED

Seven dogs with naturally acquired Capnocytophaga keratitis.

PROCEDURES

Medical records of dogs with a clinical diagnosis of keratitis and corneal cultures positive for Capnocytophaga spp. were reviewed. Dog signalment, medical history, clinical findings, and diagnostic assay results were recorded.

RESULTS

Breeds included Boston terrier (n = 3 dogs), Rat terrier (n = 2), and single cases of mixed breed and Pug. All dogs examined had expansive corneal ulceration involving the majority of the corneal surface. Marked corneal infiltrates, keratomalacia, and hypopyon were present. Progression of corneal disease was rapid with extensive dissolution of the corneal stroma. Corneal lesions progressed to catastrophic perforations within 24 h of the initial examination in three dogs, requiring enucleation. One globe was enucleated after failure to resolve with long-term medical therapy. Globes and vision were retained in three dogs following aggressive medical therapy (two dogs) or 360° conjunctival graft surgery (one dog). Capnocytophaga cynodegmi, Capnocytophaga canimorsus, or unspeciated Capnocytophaga spp. were cultured from corneal samples of all dogs. Long, thin, gram-negative rods were present during cytological evaluation of the cornea in some dogs. Histopathologic evaluation of enucleated globes revealed severe and diffuse neutrophilic and collagenolytic keratitis.

CONCLUSIONS

Capnocytophaga keratitis is a severe, rapidly progressive corneal infection in dogs that is associated with diffuse corneal involvement, extensive keratomalacia, and a relatively poor prognosis. Clinical features of canine Capnocytophaga keratitis are similar to human cases of this infection.

Identification of Virulent Capnocytophaga canimorsus Isolates by Capsular Typing

Capnocytophaga canimorsus is a dog oral commensal that causes rare but severe infections in humans. C. canimorsus was recently shown to be endowed with a capsular polysaccharide implicated in resistance to the innate immune system of the host. Here, we developed the first C. canimorsus capsular serotyping scheme. We describe nine different serovars (A to I), and this serotyping scheme allowed typing of 25/25 isolates from human infections but only 18/52 isolates from dog mouths, indicating that the repertoire of capsules in the species is vast. However, while only three serovars (A, B, and C) covered 88% of the human isolates tested (22/25), they covered only 7.7% of the dog isolates (4/52). Serovars A, B, and C were found 22.9-, 14.6-, and 4.2-fold more often, respectively, among human isolates than among dog isolates, with no geographical bias, implying that isolates endowed with these three capsular types are more virulent for humans than other isolates. Capsular serotyping would thus allow identification of virulent isolates in dogs, which could contribute to the prevention of these infections. To this end, we developed a PCR typing method based on the amplification of specific capsular genes.

Only a subset of C. canimorsus strains is dangerous for humans

Capnocytophaga canimorsus are gram-negative bacteria living as commensals in the mouth of dogs and cats. C. canimorsus cause rare but life-threatening generalized infections in humans that have been in contact with a dog or a cat. Over the last years we collected 105 C. canimorsus strains from different geographical origins and from severe human infections or healthy dogs. All these strains were analyzed by 16S rDNA sequencing and a phylogenetic tree revealed two main groups of bacteria instead of one with no relation to the geographical origin. This branching was confirmed by the whole-genome sequencing of 10 strains, supporting the evidence of a new Capnocytophaga species in dogs. Interestingly, 19 out of 19 C. canimorsus strains isolated from human infections belonged to the same species. Furthermore, most strains from this species could grow in heat-inactivated human serum (HIHS) (40/46 tested), deglycosylate IgM (48/66) and were cytochrome-oxidase positive (60/66) while most strains from the other species could not grow in HIHS (22/23 tested), could not deglycosylate IgM (33/34) and were cytochrome-oxidase negative (33/34). Here, we propose to call Capnocytophaga canis (Latin: dog) the novel, presumably less virulent dog-hosted Capnocytophaga species and to keep the name C. canimorsus for the species including human pathogens.

Non-pathogenic Neisseria: members of an abundant, multi-habitat, diverse genus

The genus Neisseria contains the important pathogens Neisseria meningitidis and Neisseria gonorrhoeae. These Gram-negative coccoid bacteria are generally thought to be restricted to humans and inhabit mucosal surfaces in the upper respiratory and genito-urinary tracts. While the meningococcus and gonococcus have been widely studied, far less attention has been paid to other Neisseria species. Here we review current knowledge of the distribution of commensal Neisseria in humans and other hosts. Analysis of the microbiome has revealed that Neisseria is an abundant member of the oropharyngeal flora, and we review its potential impact on health and disease. Neisseria also exhibit remarkable diversity, exhibiting both coccoid and rod-shaped morphologies, as well as environmental strains which are capable of degrading complex organic molecules.

New iron acquisition system in Bacteroidetes

Capnocytophaga canimorsus, a dog mouth commensal and a member of the Bacteroidetes phylum, causes rare but often fatal septicemia in humans that have been in contact with a dog. Here, we show that C. canimorsus strains isolated from human infections grow readily in heat-inactivated human serum and that this property depends on a typical polysaccharide utilization locus (PUL), namely, PUL3 in strain Cc5. PUL are a hallmark of Bacteroidetes, and they encode various products, including surface protein complexes that capture and process polysaccharides or glycoproteins. The archetype system is the Bacteroides thetaiotaomicron Sus system, devoted to starch utilization. Unexpectedly, PUL3 conferred the capacity to acquire iron from serotransferrin (STF), and this capacity required each of the seven encoded proteins, indicating that a whole Sus-like machinery is acting as an iron capture system (ICS), a new and unexpected function for Sus-like machinery. No siderophore could be detected in the culture supernatant of C. canimorsus, suggesting that the Sus-like machinery captures iron directly from transferrin, but this could not be formally demonstrated. The seven genes of the ICS were found in the genomes of several opportunistic pathogens from the Capnocytophaga and Prevotella genera, in different isolates of the severe poultry pathogen Riemerella anatipestifer, and in strains of Bacteroides fragilis and Odoribacter splanchnicus isolated from human infections. Thus, this study describes a new type of ICS that evolved in Bacteroidetes from a polysaccharide utilization system and most likely represents an important virulence factor in this group.

Emerging and Re-Emerging Zoonoses of Dogs and Cats

Simple Summary

Dogs and cats have been sharing our environment for a long time and as pets they bring major psychological well-being to our modern urbanized society. However, they still can be a source of human infection by various pathogens, including viruses, bacteria, parasites, and fungi.

Abstract

Since the middle of the 20th century, pets are more frequently considered as “family members” within households. However, cats and dogs still can be a source of human infection by various zoonotic pathogens. Among emerging or re-emerging zoonoses, viral diseases, such as rabies (mainly from dog pet trade or travel abroad), but also feline cowpox and newly recognized noroviruses or rotaviruses or influenza viruses can sicken our pets and be transmitted to humans. Bacterial zoonoses include bacteria transmitted by bites or scratches, such as pasteurellosis or cat scratch disease, leading to severe clinical manifestations in people because of their age or immune status and also because of our closeness, not to say intimacy, with our pets. Cutaneous contamination with methicillin-resistant Staphylococcus aureus, Leptospira spp., and/or aerosolization of bacteria causing tuberculosis or kennel cough are also emerging/re-emerging pathogens that can be transmitted by our pets, as well as gastro-intestinal pathogens such as Salmonella or Campylobacter. Parasitic and fungal pathogens, such as echinococcosis, leishmaniasis, onchocercosis, or sporotrichosis, are also re-emerging or emerging pet related zoonoses. Common sense and good personal and pet hygiene are the key elements to prevent such a risk of zoonotic infection.