Biochemical markers and protein pattern analysis for canine coagulase-positive staphylococci and their distribution on dog skin

Methicillin-resistant coagulase-positive staphylococci in new, middle-aged, and old veterinary hospitals in southern Thailand: A preliminary study

Background and Aim

Methicillin-resistant coagulase-positive staphylococci (MRCoPS) cause pyoderma, dermatitis, and nosocomial infection. Numerous factors, including indiscriminate antimicrobial use (AMU) in veterinary medicine, cleaning practices, and AMU in hospitals, contribute to MRCoPS. However, the relationship between hospital age and MRCoPS has not yet been investigated. This study aimed to estimate the prevalence of MRCoPS in the treatment and operation rooms of new, middle-aged, and old veterinary hospitals.

Materials and Methods

Samples were collected from small animal hospitals in Surat Thani, Nakhon Si Thammarat, and Songkhla in Thailand. Hospitals were defined as those that had been in operation for 5 years (new, n = 5), 5-15 years (middle-aged, n = 6), or >15 years (old, n = 3). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used to identify 280 samples, and duplex polymerase chain reaction was used to identify resistance genes (mecA and blaZ). The VITEK2® automated system was then used to determine the minimum inhibitory concentration.

Results

A total of 57 Staphylococcus species were identified and classified as coagulase-positive staphylococci (CoPS) (22/57, 38.60%) or coagulase-negative staphylococci (35/57, 61.40%), respectively. Nine of the 22 CoPS (40.90%) harbored the mecA gene, and 21 isolates (95.45%) harbored the blaZ gene. Interestingly, more MRCoPS was found in new hospitals (six isolates) than in middle-aged (one isolate) and old hospitals (two isolates), although there was no statistically significant difference in the presence of MRCoPS across new, middle-aged, and old veterinary hospitals (p = 0.095), Kruskal-Wallis test. There is a need for further detailed studies, including an increase in the number of hospitals in various locations.

Conclusion

MRCoPS is a nosocomial pathogen that causes zoonotic and recurrent infections in veterinary hospitals. The prevalence of MRCoPS tended to be higher in new hospitals. Areas with heavy animal contact, such as hospital floors, are areas of particular concern, and cleaning/disinfection of these areas must be highlighted in hygiene regimens.

Nasal Staphylococcus aureus and S. pseudintermedius carriage in healthy dogs and cats: a systematic review of their antibiotic resistance, virulence and genetic lineages of zoonotic relevance

The molecular ecology of Staphylococcus aureus, Staphylococcus pseudintermedius and their methicillin-resistant strains in healthy dogs and cats could serve as good models to understand the concept of bacterial zoonosis due to animal companionship. This study aims to provide insights into pooled prevalence, genetic lineages, virulence and antimicrobial resistance (AMR) among healthy dogs and cats. Original research and brief communication articles published from 2001 to 2021 that reported the nasal detection of S. aureus and S. pseudintermedius in healthy dogs and cats in the community, homes and outside veterinary clinics were examined and analysed. Forty-nine studies were eligible and included in this systematic review. The pooled prevalence of nasal carriage of S. aureus/methicillin-resistant S. aureus (MRSA) in healthy dogs and cats were 10.9% (95% CI: 10.1-11.9)/2.8% (95% CI: 2.4-3.2) and 3.2% (95% CI: 1.9-4.8)/0.5% (95% CI: 0.0-1.1), respectively. Conversely, the pooled prevalence of S. pseudintermedius/methicillin-resistant S. pseudintermedius (MRSP) in healthy dogs and cats were 18.3% (95% CI: 17.1-19.7)/3.1% (95% CI: 2.5-3.7) and 1.3% (95% CI: 0.6-2.4)/1.2% (95% CI: 0.6-2.3), respectively. Although highly diverse genetic lineages of S. aureus were detected in healthy dogs and cats, MSSA-CC1/CC5/CC22/CC45/CC121/CC398 and MRSA-CC5/CC93/CC22/CC30 were mostly reported in dogs; and MSSA-CC5/CC8/CC15/CC48 and MRSA-CC22/CC30/CC80 in cats. Of note, MSSA-CC398 isolates (spa-types t034 and t5883) were detected in dogs. Genetic lineages often associated with MSSP/MRSP were ST20/ST71, highlighting the frequent detection of the epidemic European MRSP-ST71 clone in dogs. S. aureus isolates carrying the luk-S/F-PV, tst, eta, etb and etd genes were seldomly detected in dogs, and luk-S/F-PV was the unique virulence factor reported in isolates of cats. S. pseudintermedius isolates harbouring the luk-S/F-I, seint and expA genes were frequently found, especially in dogs. High and diverse rates of AMR were noted, especially among MRSA/MRSP isolates. There is a need for additional studies on the molecular characterization of isolates from countries with under-studied nasal staphylococci isolates.

Prevalence of antimicrobial-resistant staphylococci in nares and affected sites of pet dogs with superficial pyoderma

Currently, antimicrobial-resistant staphylococci, particularly methicillin-resistant Staphylococcus pseudintermedius (MRSP), are frequently isolated from canine superficial pyoderma in Japan. However, little is known regarding the nasal prevalence of MRSP in pet dogs. Here, we determined the prevalence of antimicrobial-resistant staphylococci in nares and affected sites of pet dogs with superficial pyoderma. Of the 125 nares and 108 affected sites of pet dogs with superficial pyoderma, 107 (13 species) and 110 (eight species) staphylococci strains, respectively, were isolated. The isolation rate of S. pseudintermedius from pyoderma sites (82/110 strains, 74.5%) was significantly higher than that from nares (57/107 strains, 53.3%) (P<0.01). Notably, the prevalence of MRSP (18/57 strains, 31.6%) in nares was equivalent to that in pyoderma sites (28/82 strains, 34.1%). Furthermore, the phenotypes and genotypes of antimicrobial resistance in MRSP strains from nares were similar to those from pyoderma sites. Our findings revealed that the prevalence of antimicrobial-resistant staphylococci in the nares of pet dogs with superficial pyoderma is the same level as that in affected sites. Therefore, considerable attention should be paid to the antimicrobial resistance of commensal staphylococci in companion animals.

Enterotoxin gene profile of methicillin-resistant Staphylococcus pseudintermedius isolates from dogs, humans and the environment

PURPOSE

This study aimed to detect and identify staphylococcal enterotoxin (SE) genes in methicillin-resistant Staphylococcus pseudintermedius (MRSP) strains from different sources, and to investigate the relationship between their sequence types (STs) and SE gene patterns.

METHODOLOGY

The profiles of 17 SE genes in 93 MRSP strains isolated from dogs (n=43), humans (n=18) and the environment (n=32) were detected by PCR. Multilocus sequence typing (MLST), SCCmec typing and pulsed-field gel electrophoresis (PFGE) were used to analyse the clonal relatedness between the molecular type and SE gene profiles.Results/Key findings. The human MRSP strains harboured the greatest number of SE genes (12/17; sea, sec, seg, sei, sek, sel, sem, sen, seo, sep, seq and tst-1) compared to those from dogs (5/17; sec, sel, sem, seq and tst-1) and environmental sources (3/17; sec, seq and tst-1). Using MLST and PFGE, different SE gene profiles were found within the same clonal type.

CONCLUSION

We show that isolates of MRSP vary in their virulence gene profiles, depending on the source from which they have been isolated. This insight should encourage the development of appropriate monitoring and mitigation strategies to reduce the transmission of MRSP in veterinary hospitals and households.

Development of a set of multiplex PCRs for detection of genes encoding cell wall-associated proteins in Staphylococcus pseudintermedius isolates from dogs, humans and the environment

Staphylococcus pseudintermedius commonly colonizes the skin of dogs, whilst nasal carriage may occur in humans who are in contact with dogs or the environment of veterinary hospitals. Genes encoding cell wall-associated (CWA) proteins have been described in Staphylococcus aureus but knowledge of their occurrence in S. pseudintermedius is still limited. The aim of the study was to develop a method to detect S. pseudintermedius surface protein genes (sps) encoding CWA proteins, and to examine the distribution of the genes in isolates from different sources. Four multiplex PCR assays (mPCR) were developed for detection of 18 sps genes, with 4-5 genes detected per mPCR. These were applied to 135 S. pseudintermedius isolates from carriage sites (n=35) and infected sites (n=35) in dogs, from the nasal cavity of humans (n=25), and from the environment of a veterinary hospital (n=40). The mPCRs were shown to detect all 18 known sps genes, and no discrepancies were found between uniplex and mPCR results. The mPCRs could detect at least 1pg/μl of DNA template. A total of 23 sps gene profiles were found among the 135 isolates, with diverse gene combinations. Only spsD, spsF, spsI, spsO, spsP, and spsQ were not detected in all isolates. spsP and spsQ were more frequently detected in the canine isolates from infected sites than from carriage sites. This finding suggests that these two genes may play a role in pathogenicity, whereas the presence of the 12 sps genes may contribute to adherence function at all surfaces where carriage occurs.

Distribution of methicillin-resistant coagulase-positive staphylococci (MRCoPS) in a surgical unit and cystotomy operation sites in a veterinary teaching hospital

This study aimed to investigate the spread of methicillin-resistant coagulase-positive staphylococci (MRCoPS) among veterinary staff, hand-touch sites and surgical tissue during cystotomy operations on cats and dogs that were patients, and to analyze the genetic relatedness and antimicrobial resistance profiles of the isolates. Human and environmental samples were obtained from the nasal passageways of 12 surgeons and veterinary assistants and from 29 hand-touch sites of instruments in operative units and subjected to bacterial isolation and enumeration. Swab samples were collected in triplicate from 29 dogs and three cats at the site of incision, from the incision area, from the peritoneum during surgery and from the peritoneum before suture. MRCoPS were identified by mecA gene detection and characterized by their antibiogram profile, SCCmec type and pulsed-field gel electrophoresis. Twenty-four staphylococci were isolated, derived from one veterinary assistant, 12 operating room floor areas and hand-touch sites, three dogs and one cat. Methicillin-resistant S. pseudintermedius (MRSP) was found on an electric clipper and rebreathing circuits in the operating room. Three dogs were positive for MRSP during surgery, and one methicillin-resistant S. aureus (MRSA) was detected in a cat. All MRCoPS were resistant to doxycycline, erythromycin, clindamycin and enrofloxacin, but no patients developed surgical site infections. According to their genotypic patterns, the clones obtained from the environment and human sources differed from the animal clones. Despite intensive hygienic management, a variety of MRCoPS clones were present within the surgical unit and during surgery.

Strain typing and antimicrobial susceptibility of methicillin-resistant coagulase-positive staphylococcal species in dogs and people associated with dogs in Thailand

AIMS

This study was to investigate and to characterize methicillin-resistant coagulase-positive staphylococci (MRCoPS) harboring in dogs and people associated with dogs in Thailand.

METHODS AND RESULTS

Staphylococci were collected from 100 dogs, 100 dog owners, 200 small animal veterinarians and 100 people without pet association. Species of MRCoPS were identified phenotypically and genotypically. Molecular characteristics were determined by multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE) and SCCmec typing, and antimicrobial susceptibility was assayed by broth microdilution and by microarray analysis for resistance genes. Methicillin-resistant Staphylococcus pseudintermedius (MRSP), methicillin-resistant Staphylococcus schleiferi subsp. coagulans (MRSSc) and methicillin-resistant Staphylococcus aureus (MRSA) were isolated from dogs (45, 17 and 1%, respectively), veterinarians (8, 2 and 1·5%, respectively) and dog owners (3, 2 and 0%, respectively). Seventeen sequence types (STs) were identified among 83 MRSP isolates which specifically carried SCCmec V, II-III, ΨSCCmec57395 and three uncharacterized SCCmec types. MRSP ST 45, 68 and novel STs including 169, 178, 181 and 183 were shared among canine and human isolates. Most of MRSA ST398 and MRSSc carried SCCmec type V. The MRCoPS commonly displayed multiple resistances to tested antimicrobials and carried various resistance genes.

CONCLUSION

Variety of MRCoPS, especially new MRSP clones, distributed in dogs and people in Thailand.

SIGNIFICANCE AND IMPACT OF THE STUDY

The existence of MRCoPS circulating between dogs and humans in Thailand provides indirect evidence of interspecies transmission and represents a potential public health hazard.

Synergistic hemolysis between β-lysin–producing Staphylococcus species and Rothia nasimurium in primary cultures of clinical specimens obtained from dogs

Nonhemolytic isolates of catalase-positive, Gram-positive cocci were observed that produced strong synergistic hemolysis with colonies of Staphylococcus pseudintermedius and Staphylococcus schleiferi subsp. coagulans in primary cultures of clinical specimens from dogs. The isolates appeared similar to nonhemolytic staphylococci but were not identified with conventional biochemical tests or commercial biochemical test kits. Partial 16S ribosomal RNA gene sequences from each of 9 tested isolates were nearly identical to that of Rothia nasimurium. The isolates produced positive Christie–Atkins–Munch–Peterson test reactions with Staphylococcus aureus (ATCC strain 25923) and Staphylococcus intermedius Hajek (ATCC strain 49052). The latter was identified in the current study as S. pseudintermedius. Rothia nasimurium appears to be a previously unreported commensal organism in dogs. Its potential significance as an opportunistic contributor to polymicrobial infections in dogs is not known.

Evaluation of cefoxitin disk diffusion breakpoint for detection of methicillin resistance in Staphylococcus pseudintermedius isolates from dogs

Cefoxitin disk diffusion susceptibility testing is a recommended screening method for the detection of methicillin resistance in human isolates of Staphylococcus aureus and coagulase-negative staphylococci. A retrospective analysis of 1,146 clinical isolates of Staphylococcus pseudintermedius from dogs was conducted to determine if screening by the cefoxitin disk method can be similarly useful with S. pseudintermedius. The distribution of cefoxitin growth inhibition zone diameters within this collection was bimodal and correlated well with the results of methicillin resistance gene (mecA) detection by polymerase chain reaction. Of the isolates, 5% had discordant results and, when retested, 84% of these were in agreement. While a greater diversity of isolates and interlaboratory comparisons must be tested, the current study suggests that an epidemiological breakpoint (of approximately ≤ 30 mm = resistant; ≥ 31 = susceptible) can be established to predict methicillin resistance in S. pseudintermedius.

Nasal carriage of Staphylococcus schleiferi from healthy dogs and dogs with otitis, pyoderma or both

In veterinary medicine, Staphylococcus schleiferi was previously assumed to be an inhabitant of carnivore skin, however, more recently, it has been repeatedly documented in the literature as both an inhabitant and as a pathogen. In order to determine the frequency of nasal carriage, and the methicillin susceptibility pattern of S. schleiferi from healthy dogs as well as dogs with otitis and/or pyoderma, a prospective study including 24 dogs with healthy ears and skin, 27 dogs with healthy ears and pyoderma, 15 dogs with otitis without pyoderma and 20 dogs with both otitis and pyoderma was performed. Specimens were obtained and cultured and isolates were identified as S. schleiferi based on growth and biochemical characteristics. S. schleiferi was isolated from the nares of 1 healthy dog, 3 dogs with recurrent pyoderma, 2 dogs with recurrent otitis, and 1 dog with both recurrent otitis and pyoderma. One of the S. schleiferi isolates was methicillin resistant. Nasal carriage of S. schleiferi does occur in healthy dogs as well as dogs with otitis and pyoderma. Methicillin resistant and sensitive S. schleiferi can be found in the nares of dogs with diseased ears and skin.

Staphylococcus pseudintermedius in the dog: taxonomy, diagnostics, ecology, epidemiology and pathogenicity

The dog is the natural host of Staphylococcus pseudintermedius. Many research efforts are currently being undertaken to expand our knowledge and understanding of this important canine commensal and opportunistic pathogen. The objective of this review is to summarize the current knowledge of the species, including the latest research outcomes, with emphasis on taxonomy, diagnostics, ecology, epidemiology and pathogenicity. Despite the important taxonomic changes that have occurred over the past few years, the risk of misidentification in canine specimens is low and does not have serious consequences for clinical practice. Staphylococcus pseudintermedius carriage in the dog is more frequent and genetically heterogeneous compared with that of Staphylococcus aureus in man. It appears that these staphylococcal species have evolved separately through adaptation to their respective natural hosts and differ with regard to various aspects concerning ecology, population structure and evolution of antibiotic resistance. Further understanding of the ecology and epidemiology of S. pseudintermedius is hampered by the lack of a standard method for rapid and discriminatory typing and by the limited data available on longitudinal carriage and population structure of meticillin-susceptible strains. With regard to pathogenicity, it is only now that we are starting to explore the virulence potential of S. pseudintermedius based on genomic and proteomic approaches, and more research is needed to assess the importance of individual virulence factors and the possible existence of hypervirulent strains.