Antimicrobial resistance and characterisation of staphylococci isolated from healthy Labrador retrievers in the United Kingdom

Staphylococcal carriage among captive dingoes (Canis dingo) in Victoria, Australia

The evolutionary lineage and taxonomy of the Australian dingo is controversial, however recent genomic and gut metagenomic research has suggested that dingoes are evolutionarily distinct from modern dogs. Staphylococcus species are known commensal organisms of dogs and other mammals. In this study we took the opportunity to determine the carriage rate and antimicrobial resistance profiles of Staphylococcus species from 15 captive Australian dingoes. S. pseudintermedius was the only coagulase-positive species recovered, isolated from 6/15 (40%) and 9/13 (69%) of the animals during the 2020 (winter) and 2021 (summer) sampling times, respectively. Twenty-three coagulase-negative isolates were characterised, with S. equorum being the most frequently (20/23, 87%) recovered species. Two isolates of S. equorum had their genomes sequenced to learn more about this species. Antimicrobial resistance amongst both coagulase-positive and -negative isolates was low; with resistance to only 3 of 12 antimicrobials observed: penicillin, erythromycin, and trimethoprim. We have shown that the Australian dingo is a host organism for S. pseudintermedius much like it is in dogs, however the carriage rate was lower than has previously been reported from dogs in Australia.

Canine Staphylococcaceae circulating in a Kenyan animal shelter

Animal shelters, especially in resource-poor countries, bring together pets from different regions and with different backgrounds. The crowding of such animals often results in infectious diseases, such as respiratory infections. This study characterized Staphylococcaceae from diseased and apparently healthy dogs housed in an animal shelter in Kenya, to determine their antibiotic resistance profiles, their genetic relatedness, and the presence of dominant clones. Therefore, bacteria were collected from all 167 dogs present in the shelter in June 2015 and screened for Staphylococcaceae using standard cultivation techniques. In all, 92 strains were isolated from 85 dogs and subsequently sequenced by PacBio long-read sequencing. Strains encompassed nine validated species, while S. aureus (n = 47), S. pseudintermedius (n = 21), and Mammaliicoccus (M.) sciuri (n = 16) were the three most dominant species. Two S. aureus clones of ST15 (CC15) and ST1292 (CC1) were isolated from 7 and 37 dogs, respectively. All 92 strains isolated were tested for their antimicrobial susceptibility by determining the minimum inhibitory concentrations. In all, 86 strains had resistance-associated minimal inhibitory concentrations to at least one of the following antimicrobials: tetracycline, benzylpenicillin, oxacillin, erythromycin, clindamycin, trimethoprim, kanamycin/gentamicin, or streptomycin. Many virulence-encoding genes were detected in the S. aureus strains, other Staphylococcaceae contained a different set of homologs of such genes. The presence of mobile genetic elements, such as plasmids and prophages, known to facilitate the dissemination of virulence- and resistance-encoding genes, was also assessed. The unsuspected high presence of two S. aureus clones in about 50% of dogs suggests dissemination within the shelter and a human source.IMPORTANCEMicrobiological data from sub-Saharan Africa are scarce compared to data from North America, Europe, or Asia, and data derived from dogs, the man's best friend, kept in sub-Saharan Africa are largely missing. This work presents data on Staphylococcaceae mainly isolated from the nasal cavity of dogs stationed at a Kenyan shelter in 2015. We characterized 92 strains isolated from 85 dogs, diseased and apparently healthy ones. The strains isolated covered nine validated species and we determined their phenotypic resistance and characterized their complete genomes. Interestingly, Staphylococcus aureus of two predominant genetic lineages, likely to be acquired from humans, colonized many dogs. We also detected 15 novel sequence types of Mammaliicoccus sciuri and S. pseudintermedius indicating sub-Saharan-specific phylogenetic lineages. The data presented are baseline data that guide antimicrobial treatment for dogs in the region.

Biocidal effects of a wipe-down procedure using common veterinary cleansers on microbial burden within working canine exterior coats

Introduction

Recent work demonstrating reduction of aerosolized contamination via a wipe-down procedure using common veterinary antiseptics offers promise regarding health concerns associated with cross-contamination from working canines to humans. While mechanical reduction can be achieved via a wipe-down procedure, the biocidal impact on flora within the exterior coat is unknown.

Methodology

This study assessed the biocidal impact of antiseptics on the exterior bacterial community of the canine. Lint-free towels were saturated with 2% chlorhexidine gluconate scrub, or 7.5% povidone-iodine scrub diluted at a 1:4 ratio. Treatments were rotated across the dorsal aspect of kennel housed Foxhounds (n = 30). Sterile swabs were collected in triplicate prior to, and following wipe down, stored in Amies solution at 4°C, plated onto nutrient agar and reduction in colony forming units (CFU) was measured across both treatments. Statistical analysis utilizing PROC GLM examined effects of treatment (p ≤ 0.05). Molecular analysis of the 16S rRNA gene was completed for 3 hounds.

Results

Reduction in CFU was measured (p < 0.001) for both antiseptics. Qualitative molecular data indicated that both antiseptics had a biocidal effect on the dominant microbial community on the exterior coat with gram-positive, spore-forming taxa predominating post-treatment.

Conclusion

Effective wipe-down strategies using common veterinary cleansers should be further investigated and incorporated to safeguard working canine health and prevent cross-contamination of human personnel.

Comprehensive Approaches for the Search and Characterization of Staphylococcins

Novel and sustainable approaches are required to curb the increasing threat of antimicrobial resistance (AMR). Within the last decades, antimicrobial peptides, especially bacteriocins, have received increased attention and are being explored as suitable alternatives to antibiotics. Bacteriocins are ribosomally synthesized antimicrobial peptides produced by bacteria as a self-preservation method against competitors. Bacteriocins produced by Staphylococcus, also referred to as staphylococcins, have steadily shown great antimicrobial potential and are currently being considered promising candidates to mitigate the AMR menace. Moreover, several bacteriocin-producing Staphylococcus isolates of different species, especially coagulase-negative staphylococci (CoNS), have been described and are being targeted as a good alternative. This revision aims to help researchers in the search and characterization of staphylococcins, so we provide an up-to-date list of bacteriocin produced by Staphylococcus. Moreover, a universal nucleotide and amino acid-based phylogeny system of the well-characterized staphylococcins is proposed that could be of interest in the classification and search for these promising antimicrobials. Finally, we discuss the state of art of the staphylococcin applications and an overview of the emerging concerns.

Prevalence of Staphylococcus spp. from human specimens submitted to diagnostic laboratories in South Africa, 2012-2017

Background

Although staphylococci are commensals of the skin and mucosa of humans and animals, they are also opportunistic pathogens. Some coagulase-negative Staphylococcus spp. (CoNS), such as S. haemolyticus and S. epidermidis, are reported to be zoonotic.

Objectives

The prevalence of coagulase positive (CoPS), CoNS and coagulase-variable Staphylococcus spp. isolated from human clinical cases in South Africa was investigated.

Method

Retrospective records of 404 217 diagnostic laboratory submissions from 2012 to 2017 were examined and analysed in terms of time, place and person.

Results

Of the 32 different species identified, CoPS were the most frequently isolated (74.7%), followed by CoNS (18.9%). Just over half (51.2%) of the Staphylococcus isolates were from males, while females contributed 44.8%. Patients aged 0-4 years contributed the most (21.5%) isolates, with the highest number coming from KwaZulu-Natal (32.8%). Urinary specimens accounted for 29.8% of the isolates reported. There was no variation in the number of Staphylococcus isolates reported in the autumn (25.2%), winter (25.2%), spring (25.1%) and summer (24.5%) seasons.

Conclusion

This study demonstrated the diversity of Staphylococcus spp. isolated from humans and the magnitude of infection, with the most predominant species being S. aureus and S. epidermidis.

Contribution

Although most isolates were CoPS, the isolation of CoNS seen in this study suggests a need to improve infection control measures in a South African context. More research is needed to investigate the determinants of the observed variations in the study.

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.

Antibiotic susceptibility pattern of canine coagulase positive and coagulase negative Staphylococcus spp. in a hot and dry region of India

The emergence of anti microbial resistance among Staphylococcus spp. isolated from clinical cases of canines should be continuously monitored hence the present study was formulated to ascertain the antibiotypes and methicillin resistance in coagulase positive and coagulase negative staphylococci of canine skin and associated mucous membrane affections from a hot and dry region of India. A total of 165 clinical samples were collected and Staphylococcus aureus was identified by conventional bacteriological methods and PCR. Antibiotic susceptibility test was done against commercially available antibiotic impregnated discs as per Clinical and Laboratory Standards Institute (CLSI) method. Methicillin resistance was determined by plate methods and then via PCR of mecA gene. These 165 samples yielded, 88 (53.33%) isolates of genus Staphylococcus and 46 Staphylococcus aureus and 51/88 (57.95%) isolates were coagulase positive staphylococci. Total 55 (62.5%) isolates showed susceptibility to Ceftriaxone/Sulbactum, 37 (42.05%) to Ciprofloxacin, 26 (29.55 %) to Oxacillin, 24 (27.27 %) to Penicillin, and 10 (11.36 %) to Gentamicin. Total 21 methicillin resistant Staphylococcus aureus (MRSA) and 12 methicillin resistant coagulase negative staphylococci (MRCoNS) were found on phenotypic basis whereas the mecA gene was detected in 6 /21 MRSA and 2 /12 MRCoNS isolates. Staphylococcus spp. showed increased level of resistance against commonly used antibiotics. The higher prevalence of methicillin resistance found with phenotypic methods than to mecA PCR indicates towards additional mechanisms responsible for emergence of MRS, especially in CoNS.

Comparison of corneal culture results obtained using the ESwab™ and Amies charcoal swab in canine and feline patients

OBJECTIVE

The objective of the study was to compare corneal culture results using the ESwab™ and Amies charcoal swab.

ANIMALS STUDIED

One hundred fourteen canine and fifteen feline eyes.

PROCEDURES

Retrospective analysis of Dick White Referrals bacterial and fungal corneal culture data was conducted. Results were included from canine and feline patients, which presented with suspected infectious keratitis that had samples taken using an Amies charcoal swab followed by an ESwab™ in the same eye. In respect to positive and negative cultures, a McNemar test was conducted comparing instances of disagreement between swab types, and the Kappa coefficient (κ) was calculated to assess the level of agreement between swab types.

RESULTS

The ESwab™ produced more positive corneal cultures (71/129 [55.0%]) than the Amies charcoal swab (41/129 [31.8%]). 2/129 eyes produced positive fungal cultures. Considering 37/129 eyes in which both swab types detected a positive corneal culture, the same bacterial species were cultured from each swab type in 34/37 (91.9%) eyes, and an additional bacterial species was cultured by the ESwab™ in 3/37 (8.1%) eyes. In 34/38 (89.5%), instances of disagreement between swab types, the ESwab™ showed a positive culture, and the Amies charcoal swab showed a negative culture from the same eye, and this difference was significant (p < 0.0001). There was a moderate level of agreement between results from both swab types (κ = 0.432).

CONCLUSIONS

ESwab™ sampling alone may be superior to Amies charcoal swabs for detecting presence of bacteria in suspected infectious keratitis in cats and dogs.

Transmission of Methicillin-Resistant Staphylococcus spp. from Infected Dogs to the Home Environment and Owners

Dogs with methicillin-resistant Staphylococcus spp. (MRS) infections often undergo treatment in their homes, interacting with their owners and surroundings. This close contact between dogs and owners may facilitate the interspecies transmission of MRS. Therefore, this study aimed to investigate the transmission of MRS from infected dogs to their owners and home environments. Seven households with dogs that had been diagnosed with methicillin-resistant S. pseudintermedius (MRSP) and one household with a dog with methicillin-resistant S. epidermidis (MRSE) participated in the study. Dogs, owners, and the home environments were screened for the presence of clinical MRS. A selection of 36 staphylococcal isolates were whole-genome sequenced and screened for resistance genes and virulence genes. Clinical MRS were primarily identified from the dogs and their immediate surroundings, but these were also detected in locations that were out of reach for the dogs, indicating indirect transmission. Two of eight owners carried clinical MRS in their nostrils, while one owner carried methicillin-susceptible S. pseudintermedius (MSSP). All clinical MRS were multi-resistant, and several possessed resistance genes that were not expressed phenotypically. Clinical MRSP persisted in the home environment for a prolonged period, despite infection recovery and one dog being euthanized. Regardless of the stable presence of MRSP in the surroundings, the owners in these homes remained negative, but tested positive for MSSP on three occasions.

Antimicrobial Resistance and Molecular Epidemiology of Staphylococcus aureus from Hunters and Hunting Dogs

Several studies have showed that a dog-to-human transmission of Staphylococcus aureus occurs. Hunting dogs do not have as much contact with their owners as dogs that live in the same household as the owners; however, these dogs have contact with their owners during hunting activities as well as when hunting game; therefore, we aimed to isolate S. aureus from hunters and their hunting dogs to investigate a possible S. aureus transmission. Nose and mouth samples were collected from 30 hunters and their 78 hunting dogs for staphylococcal isolation. The species identification was performed using MALDI-TOF. The antimicrobial susceptibility profiles were accessed using the Kirby-Bauer method and respective antimicrobial resistance genes were investigated by PCR. Multilocus sequence typing (MLST) and spa- and agr-typing was performed in all S. aureus isolates. S. aureus were detected in 10 (30%) human samples and in 11 (15.4%) dog samples of which 11 and 5 were methicillin-resistant S. aureus (MRSA). Other staphylococci were identified, particularly, S. pseudintermedius. Most S. aureus isolates were resistant to penicillin, erythromycin, and tetracycline. Evidence of a possible transmission of S. aureus between human and dogs was detected in three hunters and their dogs. S. aureus isolates were ascribed to 10 STs and 9 spa-types. A moderate colonization of S. aureus in hunting dogs and their owners was detected in this study. A few dog-to-dog and dog-to-human possible transmissions were identified.

Prevalence and Patterns of Antimicrobial Resistance among Escherichia coli and Staphylococcus spp. in a Veterinary University Hospital

The occurrence of antimicrobial resistance in commensal strains of Escherichia coli and Staphylococcus spp. was investigated in 320 samples collected from patients and the environment of a veterinary university hospital-specifically, the consultation area (CA) and intensive care unit (ICU). E. coli was isolated in 70/160 samples (44%), while Staphylococcus spp. were isolated in 110/160 (69%) samples. The occurrence of multidrug-resistant (MDR) isolates from CA and ICU admission were similar for E. coli (1/12 (8%) versus 4/27 (15%), respectively) and Staphylococcus spp. (10/19 (53%) versus 26/50 (52%), respectively). MDR E. coli isolates increased significantly at hospital discharge (18/31; 58%; p = 0.008). Antimicrobial treatment administered during hospitalization was a risk factor for carriage of MDR E. coli (OR, 23.9; 95% CI: 1.18-484.19; p = 0.04) and MDR Staphylococcus spp. (OR, 19.5; 95% CI 1.30-292.76; p = 0.02), respectively. The odds ratio for MDR E. coli was 41.4 (95% CI 2.13-806.03; p = 0.01), if the administration of fluoroquinolones was evaluated. The mecA gene was detected in 19/24 (79%) coagulase-positive Staphylococcus spp. isolates resistant to oxacillin. High rates of MDR Staphylococcus spp. were reported. Hospitalization in the ICU and antimicrobial treatment were risk factors for colonization by MDR commensal bacteria.

Methicillin-Resistant Coagulase Negative Staphylococci and Their Antibiotic Susceptibility Pattern from Healthy Dogs and Their Owners from Kathmandu Valley

This cross-sectional study was designed to identify information on the frequency, antimicrobial resistance and species diversity of methicillin-resistant coagulase negative staphylococci (MRCoNS) among pet dogs and humans within households. Fifty five nasal swabs each from dogs and their owners were collected. MRCoNS were identified based on gram staining, culture on mannitol salt agar, biochemical tests, and mecA gene amplification. The antibiotic susceptibility of the isolates was assessed by a disc diffusion test. Uniplex and multiplex polymerase chain reaction (PCR) were employed for the species identification of MRCoNS and SCCmec typing, respectively. Species were further confirmed by MALDI-TOF-MS. The prevalence of MRCoNS was 29% in dog owners and 23.6% in dogs. Four different species of MRCoNS, Staphylococci saprophyticus (48.3%), S. haemolyticus (24.1%), S. warneri (17.2%), and S. epidermidis (10.3%), were detected. Two isolates each from dog owners and dogs showed a constitutive resistance to macrolide-lincosamide-streptogramin B (cMLSB) resistance, eight isolates each from dogs and their owners showed a macrolide-streptogramin B (MSB) resistance, and only two isolates from dog owners revealed an inducible resistance to macrolide-lincosamide-streptogramin B (iMLSB) resistance. SCCmec types were SCCmec type IV (55.2%), SCCmec type V (24.1%), SCCmec III (10.3%), SCCmec II (3.4%); two isolates were non-typable. MRCoNS are prevalent and genetically diverse in companion animals and humans. Different species of MRCoNS were found in dogs and their owners.

Acquisition and carriage of multidrug-resistant organisms in dogs and cats presented to small animal practices and clinics in Switzerland

BACKGROUND

The emergence and spread of multidrug-resistant organisms (MDRO) present a threat to human and animal health.

OBJECTIVES

To assess acquisition, prevalence of and risk factors for MDRO carriage in dogs and cats presented to veterinary clinics or practices in Switzerland.

ANIMALS

Privately owned dogs (n = 183) and cats (n = 88) presented to 4 veterinary hospitals and 1 practice.

METHODS

Prospective, longitudinal, observational study. Oronasal and rectal swabs were collected at presentation and 69% of animals were sampled again at discharge. Methicillin-resistant (MR) staphylococci and macrococci, cephalosporinase-, and carbapenemase-producing (CP) Enterobacterales were isolated. Genetic relatedness of isolates was assessed by repetitive sequence-based polymerase chain reaction and multilocus sequence typing. Risk factors for MDRO acquisition and carriage were analyzed based on questionnaire-derived and hospitalization data.

RESULTS

Admission prevalence of MDRO carriage in pets was 15.5% (95% confidence interval [CI], 11.4-20.4). The discharge prevalence and acquisition rates were 32.1% (95% CI, 25.5-39.3) and 28.3% (95% CI, 22-35.4), respectively. Predominant hospital-acquired isolates were extended spectrum β-lactamase-producing Escherichia coli (ESBL-E coli; 17.3%) and β-lactamase-producing Klebsiella pneumoniae (13.7%). At 1 institution, a cluster of 24 highly genetically related CP (bla_oxa181 and bla_oxa48 ) was identified. Multivariate analysis identified hospitalization at clinic 1 (odds ratio [OR], 5.1; 95% CI, 1.6-16.8) and days of hospitalization (OR 3-5 days, 4.4; 95% CI, 1.8-10.9; OR > 5 days, 6.2; 95% CI, 1.3-28.8) as risk factors for MDRO acquisition in dogs.

CONCLUSIONS

Veterinary hospitals play an important role in the selection and transmission of MDRO among veterinary patients.

Prevalence of Antimicrobial Resistance in Bacterial Isolates from Dogs and Cats in a Veterinary Diagnostic Laboratory in Colombia from 2016-2019

The susceptibility to antimicrobials of bacterial isolates from dogs (n = 1256) and cats (n = 94) was retrospectively evaluated in a veterinary diagnostic laboratory over a 4-year period (2016–2019). Out of 1316 isolates in dogs, 771 were Staphylococcus spp. distributed as follows: Staph. pseudointermedius (n = 406), Staph. intermedius (n = 160), Staph. aureus (n = 104), and Staph. coagulase-negative (n = 101). In common, all Staphylococcus spp. showed a high prevalence (20–50%) of resistance to ampicillin, cephalosporin, enrofloxacin, gentamicin, tetracycline, and trimethoprim-sulfonamide, but a low prevalence (1–10%) of resistance to amoxicillin-clavulanate. With regards to the other families of bacteria, the number of antimicrobials for which resistance was high (>20%) in dogs was: Enterobacteriaceae (7/12), Enterococcus spp. (10/16), E. coli (11/15), Pseudomonas spp. (10/13), and Streptococcus spp. (4/9). For urinary tract infections caused by E. coli or Enterobacteriaceae (Klebsiella spp., Proteus spp.), amikacin and florfenicol were the only drugs that demonstrated 100% in vitro efficacy. Multi-drug resistance was observed in 18.7% (246/1316) and 22% (21/97) of the isolates from dogs and cats, respectively. Except for Pseudomonas spp., known for intrinsic resistance, resistance in other bacteria was likely attributed to high selection pressure. In conclusion, empirical antimicrobial use cannot be recommended to treat most common infections, and selection should be based on results from susceptibility testing.

Molecular Detection and Characterization of the mecA and nuc Genes From Staphylococcus Species (S. aureus, S. pseudintermedius, and S. schleiferi) Isolated From Dogs Suffering Superficial Pyoderma and Their Antimicrobial Resistance Profiles

Canine superficial pyoderma (CSP) is a bacterial infection secondary to several skin diseases of the dog. Staphylococcus pseudintermedius, which is a commensal bacterium of the dog's skin, is the leading agent found in dogs affected by CSP, which can progress to deep pyoderma. It is also of clinical significance because S. pseudintermedius strains carry antimicrobial resistance genes, mainly the mecA gene. In this descriptive longitudinal study, molecular characterization of bacterial isolates from dogs affected by CSP was performed in addition to phenotyping, antimicrobial profiling, and assessment of resistance carriage status. Fifty dogs (24 females and 26 males) attending the CES University Veterinary Teaching Hospital were included in the study. CSP was confirmed according to clinical signs and cytological examination. Swabs were taken from active skin lesions for bacterial culture, and phenotyping and antimicrobial resistance profiles were assessed using API-Staph phenotyping and the Kirby–Bauer method, respectively. We also performed molecular detection and characterization of the mecA and nuc encoding gene of coagulase-positive Staphylococci. The mecA gene frequency was established by qPCR amplification of a 131bp gene fragment. Data were evaluated by descriptive statistics. Erythema, peeling, pruritus, and alopecia were the predominant symptoms (72, 56, and 46%, respectively). We isolated bacteria compatible with Staphylococcus species from all samples tested. API phenotyping showed 83.1 to 97.8% compatibility with S. pseudintermedius. PCR-genotyping resulted in 15, 3, and 1 isolates positive for S. pseudintermedius, S. aureus, and S. schleiferi, respectively. Isolated strains showed high susceptibility to Imipenem, Ampicillin/Sulbactam, and Rifampicin (100, 94, and 92%, respectively). The highest resistance was against Vancomycin and Trimethoprim/Sulfamethoxazole (98 and 74%, respectively). S. pseudintermedius, S. aureus, and S. schleiferi isolates were cloned and shared 96% sequence homology. Finally, we found 62% carriage status of the mecA gene in isolates of CSP patients, although only 36% of the isolates were methicillin-resistant. Identification of three Staphylococcus species causing CSP, high-level resistance against conventional antimicrobials, and carriage of the mecA gene highlight the importance of performing molecular characterization of bacteria causing dermatological conditions in dogs.

Geographical Variations in Virulence Factors and Antimicrobial Resistance Amongst Staphylococci Isolated From Dogs From the United Kingdom and Romania

The objective of this study was to compare virulence and resistance factors of mucosal and cutaneous staphylococci from dogs with pyoderma in the UK and Romania, two countries with different approaches to antimicrobial use in companion animals. Staphylococcal isolates (n = 166) identified to the species level as being Staphylococcus pseudintermedius or coagulase negative (CoNS) were analyzed for their antimicrobial resistance (AMR) profile and presence of resistance and virulence genes. Of the investigated isolates, 26 were methicillin-resistant S. pseudintermedius (MRSP), 89 were methicillin-susceptible S. pseudintermedius (MSSP) and 51 were coagulase negative staphylococci (CoNS). A significantly larger number of isolates originating from Romania were resistant to clindamycin, tetracycline, and chloramphenicol compared to the UK isolates (P < 0.05). Resistance to amoxicillin-clavulanic acid, gentamicin, and trimethoprim-sulphamethoxazole was more evident in UK isolates. Fusidic acid resistance was common in Staphylococcus spp. isolates from both countries. Most isolates carried virulence factors associated with siet (exfoliative toxin) and luk (leucocidin) genes. All MRSP UK isolates exhibited fusidic acid resistance genes whilst this was very rare in the MRSP isolates from Romania. The chlorhexidine resistance gene qacA/B was frequently identified in CoNS isolates from the UK (P < 0.001). The current study documented differences in antimicrobial resistance profiles of Staphylococcus spp. isolates from dogs in two geographical locations in Europe, which could reflect differences in antimicrobial prescribing patterns. The study also highlights the need for further studies and interventions on antimicrobial use, prescribing patterns and AMR surveillance in companion animals in Romania.

Clinical, bacteriological and histopathological aspects of first-time pyoderma in a population of Iranian domestic dogs: a retrospective study

BACKGROUND

Staphylococci are the most common cause of pyoderma in dogs.

AIMS

The purpose of the present study was to investigate clinical, bacteriological and histopathological aspects of bacterial skin infections in a population of Iranian domestic dogs with first-time pyoderma.

METHODS

The study animals were 61 clinical cases of Iranian domestic dogs with first-time pyoderma. The diagnosis of pyoderma was based on the history, the presence of variable gross cutaneous lesions, positive findings on microscopic examination of surface cytology and histopathological findings.

RESULTS

Detection of pyoderma amongst adult dogs was significantly higher than puppies (P=0.001). Large breed dogs were presented more frequently for pyoderma in comparison to small breeds (P=0.002). Bacterial species were recovered from 43 of the 61 (70.49%) studied animals. No isolates were recovered from 18 studied dogs. The most frequently recovered bacterial genus was Staphylococcus (32/43 isolates, 74.41%) including: S. epidermidis (22/43 isolates, 51.16%), S. aureus (7/43 isolates, 16.27%), and S. pseudintermedius (3/43 isolates, 6.97%). Staphylococci species resistance was most commonly seen against amoxicillin (94.11%), penicillin (83.35%), and ampicillin (76.47%). Resistant to cephalexin and cefoxitin was 5.88% and 2.94%, respectively. A total of 27 of the staphylococci isolated (84.37%) were resistant to at least one antimicrobial agent and 19 isolates (59.37%) were resistant to three or more antimicrobial drugs.

CONCLUSION

A better understanding of this microbial population is critical for clarification of the pathophysiology of bacterial skin diseases.

Diagnostic accuracy of phenotypic assays for determining antimicrobial resistance status in Staphylococcus pseudintermedius isolates from canine clinical cases

This study evaluated the diagnostic test accuracy of disc diffusion relative to broth-microdilution for clinical Staphylococcus pseudintermedius isolated from dogs in Australia (n = 614). Accuracy of disc diffusion and broth-microdilution for oxacillin relative to mecA real-time PCR was also assessed. Each isolate had paired minimum inhibitory concentration and zone diameter values for ten antimicrobial agents. Data was dichotomised using Clinical and Laboratory Standards Institute susceptible and resistant clinical breakpoints. Test accuracy was reported using relative diagnostic sensitivity (RSe), specificity (RSp), likelihood ratio pairs, diagnostic odds ratio, and area-under-the receiver-operating characteristic (ROC AUC) analysis. Disc diffusion was found to have high test accuracy for most antimicrobials (ROC AUC range: 0.96 - 0.99) except rifampicin (ROC AUC = 0.80). The RSp of disc diffusion was high for all antimicrobials (range, 97.1%-100%). However, RSe was considerably variable (range, 35.7%-98.8%), particularly for amoxicillin-clavulanic acid (51.5%, 95% CI, 38.9%, 64.0%), cefoxitin (35.7%, 95% CI, 12.8%, 64.9%), and cephalothin (43.6%, 95% CI, 27.8%, 60.4%). When disc diffusion and broth-microdilution were compared to mecA real-time PCR, the overall accuracy of both assays was similar (ROC AUC, 0.99 respectively). However, the RSe for broth-microdilution (96.1%, 95% CI, 88.9%, 99.2%) was significantly higher than for disc diffusion (86.8%, 95% CI, 77.1%, 93.5%) (McNemars mid-p value 0.01). Overall, these findings demonstrate that for most antimicrobials, disc diffusion performed according to CLSI guidelines can be used to differentiate clinical S. pseudintermedius isolates that might otherwise be assessed by broth-microdilution, provided consideration is given to the performance estimates reported here.

Clonally Diverse Methicillin and Multidrug Resistant Coagulase Negative Staphylococci Are Ubiquitous and Pose Transfer Ability Between Pets and Their Owners

Sixty-eight owners and 66 pets, from 43 unrelated pet-owning households were screened for methicillin-resistant coagulase negative staphylococci (MRCoNS), potential cases of MRCoNS interspecies transmission (IT), and persistence. MRCoNS isolates were identified by microbiological and molecular tests. MLST-based phylogenetic analysis was performed in Staphylococcus epidermidis isolates. Antimicrobial susceptibility was evaluated using phenotypic and molecular methods. SCCmec type and the presence of biofilm-related ica locus was PCR-tested. Isolates suspected for MRCoNS IT cases were subjected to SmaI-PFGE analysis and individuals from positive households were followed-up for 1 year for carriage dynamics (every 3 months, T0-T4). Nineteen MRCoNS isolates from owners (27.9%) and 12 from pets (16.7%) were detected, coming from 20 households (46.5%). S. epidermidis was predominant (90 and 67% of human and animal strains, respectively), showing high phylogenetic diversity (16 STs among 24 strains). Methicillin-resistant S. epidermidis (MRSE) strains belonged to CC5 (75%), CC11 (12.5%), singleton S556 (8.3%), and S560 (4.17%). Significant host-associated differences were observed for resistance to aminoglycosides, co-trimoxazole, chloramphenicol (higher in animal isolates) and tetracycline (higher among human strains). Multidrug resistance (MDR) was common (68.4%) and associated with human strains. Great diversity of ccr and mec complexes were detected, most strains being non-typeable, followed by SCCmecIV and V. Over one third of isolates (most from owners), carried the ica locus, all MRSE CC5. Two sporadic IT cases (T0) were identified in owners and dogs from two households (4.7%), with diverse interspecies-exchanged clones detected along the sampling year, especially in dogs. A comparative analysis of all MRCoNS, with all nasal coagulase positive staphylococci (CoPS) recovered from the same individuals at T0, revealed that CoPS alone was predominant in owners and pets, followed by co-carriage of CoPS and MRCoNS in owners but single MRCoNS in pets. Statistical analyses revealed that owners are more prone to co-carriage and that co-existence of IT cases and co-carriage are positively interrelated. MRCoNS from healthy owners and their pets are genetically heterogeneous MDR strains that are spread in the community. Therefore, pets also contribute to the dissemination of successful human clones. Owner-pet inhabitancy increases the risk for staphylococcal temporal concomitance with its subsequent risk for bacterial infection and genetic exchange.

Are the Hands of Veterinary Staff a Reservoir for Antimicrobial-Resistant Bacteria? A Randomized Study to Evaluate Two Hand Hygiene Rubs in a Veterinary Hospital

Hand hygiene (HH) is the most successful intervention for hospital infection control. HH rubs with residual action are desired. This study aimed to compare the efficacy of alcohol (A-HH) and lactic acid (LA-HH) rubs, with the latter being marketed as having residual activity. We investigated reductions in bacterial colony-forming units (CFUs), prevalence of antimicrobial-resistant (AMR) organisms, and risk factors for increased counts on the hands of veterinary staff. A randomized, crossover study (53 individuals) was performed in a referral veterinary teaching hospital. Hand plates were taken before, immediately after, and 6 hours after HH. A blinded investigator counted CFUs per plate. Methicillin-resistant Staphylococcus aureus/pseudintermedius (MRSA/MRSP), Enterobacteriaceae, and Pseudomonas species (spp.) were characterized. Gender, profession, time point, and HH product were included as variables within multivariable analyses. A significant reduction in bacterial CFU was seen immediately after A-HH rub application (p < 0.001); however, neither product showed any significant residual action. Veterinarians had higher bacterial CFUs than nurses (p = 0.005); contact with patients, rather than the environment, was also associated with higher counts (p < 0.001). MRSA, MRSP, Enterobacteriaceae spp., and Pseudomonas spp. were detected on 7%, 2%, 14%, and 2% of study participant's hands (n = 208 samples), respectively. Frequent HH administration using an A-HH rub was effective at reducing bacterial CFU on hands in vivo in this veterinary hospital setting, but its use needs further encouragement in veterinary staff. The high prevalence of antimicrobial bacteria on hands is of concern; they might act as reservoirs for patients, the environment, and in-contact people.

Sick pets as potential reservoirs of antibiotic-resistant bacteria in Singapore

An analysis of 186 diagnostic reports collected from a veterinary clinic in Singapore between 2014 to 2016 showed that sick companion animals can carry bacteria that are of significance to human health. Among the 186 specimens submitted, 82 showed polymicrobial growth (45%, 82/186) and in total, 359 bacteria were isolated. Of the 359 bacteria reported, 45% (162/359) were multi-drug resistant and 18% (66/359) were extended-spectrum-beta-lactamase species. Resistance to broad-spectrum antibiotics were also observed among individual species. Namely, methicillin-resistance among Staphylococcus pseudintermedius (63%, 32/51) and Staphylococcus aureus (50%, 4/8); fluoroquinolone-resistance among Escherichia coli (40%, 17/42) and carbapenem-resistance among Klebsiella pneumoniae (7%, 2/30) were noted. Our analysis suggests that sick pets may contribute to the pool of clinically relevant antibiotic-resistant bacteria and play a role in the spread of antibiotic resistance in Singapore. A more extensive study to better understand the extent of distribution and the factors affecting transmission of antibiotic-resistant bacteria to and from pets is necessary.

Temporal trends and predictors of antimicrobial resistance among Staphylococcus spp. isolated from canine specimens submitted to a diagnostic laboratory

Background

Resistance to commonly used antimicrobials is a growing concern in both human and veterinary medicine. Understanding the temporal changes in the burden of the problem and identifying its determinants is important for guiding control efforts. Therefore, the objective of this study was to investigate temporal patterns and predictors of antimicrobial resistance among Staphylococcus spp. isolated from canine specimens submitted to the University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) between 1993 and 2009.

Methods

Retrospective data of 4,972 Staphylococcus isolates assessed for antimicrobial susceptibility using the disk diffusion method at the UKVDL between 1993 and 2009 were included in the study. Temporal trends were assessed for each antimicrobial using the Cochran-Armitage trend test. Logistic regression models were used to investigate predictors of antimicrobial resistance (AMR) and multidrug resistance (MDR).

Results

A total of 68.2% (3,388/4,972) Staphylococcus isolates were S. intermedius group (SIG), 18.2% (907/4,972) were coagulase-negative staphylococci (CoNS), 7.6% (375/4,972) were S. aureus, 5.8% (290/4,972) were S. hyicus, and S. schleiferi subsp. coagulans comprised 0.2% (12/4,972) of the isolates. The overall percentage of AMR and MDR were 77.2% and 25.6%, respectively. The highest levels of AMR were seen in CoNS (81.3%; 737/907), S. aureus (80.5%; 302/375), and SIG (77.6%; 2,629/3388). The lowest levels of AMR were observed in S. hyicus (57.9%; 168/290) and S. schleiferi subsp. coagulans (33.3%; 4/12). Overall, AMR and MDR showed significant (p<0.001) decreasing temporal trends. Significant temporal trends (both increasing and decreasing) were observed among 12 of the 16 antimicrobials covering 6 of the 9 drug classes assessed. Thus, significant increasing temporal trends in resistance were observed to β-lactams (p<0.001) (oxacillin, amoxicillin-clavulanate, cephalothin, and penicillin (p = 0.024)), aminoglycosides (p<0.001) (gentamicin, and neomycin), bacitracin (p<0.001), and enrofloxacin (p<0.001). In contrast, sulfonamide (p<0.001) (sulfadiazin) and tetracycline (p = 0.010) resistant isolates showed significant decreasing temporal trends in AMR. Staphylococcus spp., geographic region, and specimen source were significant predictors of both AMR and MDR.

Conclusions

Although not unexpected nor alarming, the high levels of AMR to a number of antimicrobial agents and the increasing temporal trends are concerning. Therefore, continued monitoring of AMR among Staphylococcus spp. is warranted. Future studies will need to identify local factors responsible for the observed geographic differences in risk of both AMR and MDR.

Impact of systemic antimicrobial therapy on mucosal staphylococci in a population of dogs in Northwest England

BACKGROUND

Antimicrobial-resistant bacteria are increasingly isolated from veterinary patients.

OBJECTIVES

To determine risk factors for antimicrobial resistance (AMR) among canine mucosal staphylococci following routine antimicrobial treatment with cefalexin (CFX), clavulanate-amoxicillin (AC), cefovecin (CVN), clindamycin (CD) or a fluoroquinolone (FQ).

ANIMALS

Mucosal swab samples (n = 463) were collected from 127 dogs pre-treatment, immediately, and at one- and three-months post-treatment.

METHODS

Staphylococci were identified phenotypically and biochemically as coagulase negative (CoNS) or coagulase positive (CoPS); CoPS were speciated by nuc gene PCR. Antimicrobial susceptibility was determined using disc diffusion and mecA gene carriage by PCR. Multilevel, multivariable models examined associations between risk factors and presence/absence of CoPS, meticillin resistance (MR), multidrug-resistance (MDR) and fluoroquinolone resistance (FQR).

RESULTS

The percentage of samples with CoNS increased and with CoPS (including S. pseudintermedius) decreased immediately post-treatment with CFX, CVN and CD (P ≤ 0.001) and one month post-treatment with CD (P = 0.003). By three months post-treatment, there was no significant difference compared to pre-treatment samples. Immediately post-treatment with FQs there was significantly increased risk of isolating MRS (P = 0.002), MDR (P = 0.002) or FQR (P = 0.013) staphylococci and of MDR following CFX treatment (P = 0.019). The percentage of samples with AMR staphylococci declined from immediately to three months post-treatment and there was no significant difference between resistance prevalence at one or three months post-treatment for most AMR traits and treatment groups. Exceptions include increased MDR following FQ (P = 0.048) or CFX (P = 0.021), at one and three months post-treatment, respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

Systemic antimicrobials impact on mucosal staphylococci. Immediately after therapy, the mucosa may be a reservoir for AMR staphylococci that are a source of mobile genetic elements carrying AMR genes.

Antibiotic resistance profiles of coagulase-positive and coagulase-negative staphylococci from pit latrine fecal sludge in a peri-urban South African community

The aim of this study was to assess pit latrine samples from a peri-urban community in KwaZulu-Natal (South Africa) for the presence of multidrug-resistant (MDR) Staphylococcus spp. Standard procedures were used to isolate Staphylococcus spp. from pit latrine fecal sludge samples, with confirmation at genus level by polymerase chain reaction (PCR). Sixty-eight randomly selected pit latrine Staphylococcus spp. isolates were further characterized by using established disk diffusion procedures. An average Staphylococcus spp. count of 2.1 × 10⁵ CFU per g fecal material was established using two randomly selected pit latrine samples. Of the 68-selected Staphylococcus spp. pit latrine isolates, 49% were identified as coagulase positive, 51% as coagulase negative and 65% (12 coagulase positive, 32 coagulase negative isolates) were categorized as MDR. The majority (66/68) of Staphylococcus spp. isolates displayed resistance to fusidic acid while only 5/68 isolates displayed resistance to chloramphenicol. The pit latrine samples analyzed in this study are a source of MDR Staphylococcus spp., highlighting the need for proper hygiene and sanitation regimes in rural communities using these facilities.

Antimicrobial resistance patterns of Staphylococcus species isolated from cats presented at a veterinary academic hospital in South Africa

Background

Antimicrobial resistance is becoming increasingly important in both human and veterinary medicine. This study investigated the proportion of antimicrobial resistant samples and resistance patterns of Staphylococcus isolates from cats presented at a veterinary teaching hospital in South Africa. Records of 216 samples from cats that were submitted to the bacteriology laboratory of the University of Pretoria academic veterinary hospital between 2007 and 2012 were evaluated. Isolates were subjected to antimicrobial susceptibility testing against a panel of 15 drugs using the disc diffusion method. Chi square and Fisher’s exact tests were used to assess simple associations between antimicrobial resistance and age group, sex, breed and specimen type. Additionally, associations between Staphylococcus infection and age group, breed, sex and specimen type were assessed using logistic regression.

Results

Staphylococcus spp. isolates were identified in 17.6% (38/216) of the samples submitted and 4.6% (10/216) of these were unspeciated. The majority (61.1%,11/18) of the isolates were from skin samples, followed by otitis media (34.5%, 10/29). Coagulase Positive Staphylococcus (CoPS) comprised 11.1% (24/216) of the samples of which 7.9% (17/216) were S. intermedius group and 3.2% (7/216) were S. aureus. Among the Coagulase Negative Staphylococcus (CoNS) (1.9%, 4/216), S. felis and S. simulans each constituted 0.9% (2/216). There was a significant association between Staphylococcus spp. infection and specimen type with odds of infection being higher for ear canal and skin compared to urine specimens. There were higher proportions of samples resistant to clindamycin 34.2% (13/25), ampicillin 32.4% (2/26), lincospectin 31.6% (12/26) and penicillin-G 29.0% (11/27). Sixty three percent (24/38) of Staphylococcus spp. were resistant to one antimicrobial agent and 15.8% were multidrug resistant (MDR). MDR was more common among S. aureus 28.6% (2/7) than S. intermedius group isolates 11.8% (2/17). One S. intermedius group isolate was resistant to all β-lactam antimicrobial agents tested.

Conclusion

S. intermedius group was the most common cause of skin infections and antimicrobial resistance was not wide spread among cats presented at the veterinary academic hospital in South Africa. However, the presence of MDR-Staphylococcus spp. and isolates resistant to all β-lactams is of both public health and animal health concern.

Nasal carriage of methicillin-resistant coagulase-negative staphylococci in healthy humans is associated with occupational pig contact in a dose-response manner

This study aimed to explore the association between occupational pig contact and human methicillin-resistant coagulase-negative staphylococci (MRCoNS) carriage. We conducted a cross-sectional study of pig exposed participants and controls in Guangdong, China, using a multi-stage sampling design. Participants provided a nasal swab for MRCoNS analysis and resulting isolates were tested for antibiotic susceptibility. The dose-response relation was examined using log binomial regression or Poisson regression models. The adjusted prevalence of MRCoNS carriage in pig exposed participants was 1.67 times (95% CI: 1.32-2.11) higher than in controls. The adjusted average number of resistance to different antibiotic classes of MRCoNS isolates from pig exposed participants was 1.67 times (95% CI: 1.46-1.91) higher than those from controls. Notably, we found the frequency and duration of occupational pig contact was associated with increased prevalence and increased number of resistance to different antibiotic classes of MRCoNS in a dose-response manner. When examining these relations by MRCoNS species, there was still evidence of similar exposure-response relations. Additionally, the proportion of tetracycline-resistant and tet(M)-containing MRCoNS isolates was significantly higher in pig exposed participants than in controls. These findings suggested a potential transmission of MRCoNS from livestock to humans by occupational livestock contact, and the presence of phenotypic and genotypic tetracycline resistance may aid in the differentiation of animal origins of MRCoNS isolates.

Patterns and predictors of antimicrobial resistance among Staphylococcus spp. from canine clinical cases presented at a veterinary academic hospital in South Africa

BACKGROUND

Antimicrobial resistance in staphylococci, often associated with treatment failure, is increasingly reported in veterinary medicine. The aim of this study was to investigate patterns and predictors of antimicrobial resistance among Staphylococcus spp. isolates from canine samples submitted to the bacteriology laboratory at the University of Pretoria academic veterinary hospital between 2007 and 2012. Retrospective data of 334 Staphylococcus isolates were used to calculate the proportion of samples resistant to 15 antimicrobial agents. The Cochran-Armitage trend test was used to investigate temporal trends and logistic regression models were used to investigate predictors of antimicrobial resistance in Staphylococcus aureus and Staphylococcus pseudintermedius.

RESULTS

Results show that 98.2% (55/56) of the S. aureus isolates were resistant to at least one drug while 42.9% were multidrug resistant. Seventy-seven percent (214/278) of the S. pseudintermedius isolates were resistant to at least one drug and 25.9% (72/278) were multidrug resistant. Resistance to lincospectin was more common among S. aureus (64.3%) than S. pseudintermedius (38.9%). Similarly, resistance to clindamycin was higher in S. aureus (51.8%) than S. pseudintermedius (31.7%) isolates. There was a significant (p = 0.005) increase in S. aureus resistance to enrofloxacin over the study period. Similarly, S. pseudintermedius exhibited significant increasing temporal trend in resistance to trimethoprim-sulphamethoxazole (p = 0.004), clindamycin (p = 0.022) and orbifloxacin (p = 0.042). However, there was a significant decreasing temporal trend in the proportion of isolates resistant to doxycycline (p = 0.041), tylosin (p = 0.008), kanamycin (p = 0.017) and amoxicillin/clavulanic acid (p = 0.032).

CONCLUSIONS

High levels of multidrug resistance and the increasing levels of resistance to sulphonamides, lincosamides and fluoroquinolones among Staphylococcus spp. isolates in this study are concerning. Future studies will need to investigate local drivers of antimicrobial resistance to better guide control efforts to address the problem.

Burden and predictors of Staphylococcus aureus and S. pseudintermedius infections among dogs presented at an academic veterinary hospital in South Africa (2007-2012)

Background

Staphylococci are commensals of the mucosal surface and skin of humans and animals, but have been implicated in infections such as otitis externa, pyoderma, urinary tract infections and post-surgical complications. Laboratory records provide useful information to help investigate these infections. Therefore, the objective of this study was to investigate the burdens of these infections and use multinomial regression to examine the associations between various Staphylococcus infections and demographic and temporal factors among dogs admitted to an academic veterinary hospital in South Africa.

Methods

Records of 1,497 clinical canine samples submitted to the bacteriology laboratory at a veterinary academic hospital between 2007 and 2012 were included in this study. Proportions of staphylococcal positive samples were calculated, and a multinomial logistic regression model was used to identify predictors of staphylococcal infections.

Results

Twenty-seven percent of the samples tested positive for Staphylococcus spp. The species of Staphylococcus identified were S. pseudintermedius (19.0%), S. aureus (3.8%), S. epidermidis (0.7%) and S. felis (0.1%). The remaining 2.87% consisted of unspeciated Staphylococcus. Distribution of the species by age of dog showed that S. pseudintermedius was the most common (25.6%) in dogs aged 2–4 years while S. aureus was most frequent (6.3%) in dogs aged 5–6 years. S. pseudintermedius (34.1%) and S. aureus (35.1%) were the most frequently isolated species from skin samples. The results of the multivariable multinomial logistic regression model identified specimen, year and age of the dog as significant predictors of the risk of infection with Staphylococcus. There was a significant temporal increase (RRR = 1.17; 95% CI [1.06–1.29]) in the likelihood of a dog testing positive for S. pseudintermedius compared to testing negative. Dogs ≤ 8 years of age were significantly more likely to test positive for S. aureus than those >8 years of age. Similarly, dogs between 2–8 years of age were significantly more likely to test positive for S. pseudintermedius than those >8 years of age. In addition, dogs 2–4 years of age (RRR = 1.83; 1.09–3.06) were significantly more likely to test positive for S. pseudintermedius compared to those <2 years of age. The risk of infection with S. pseudintermedius or S. aureus was significantly higher in ear canal and skin specimens compared to other specimens.

Conclusions

The findings suggest that S. pseudintermedius and S. aureus were the most commonly isolated species from dogs presented at the study hospital. Age of the dog and the location of infection were significant predictors of infection with both Staphylococcus species investigated. Significant increasing temporal trend was observed for S. pseudintermedius but not S. aureus. This information is useful for guiding clinical decisions as well as future research.

Characterisation of methicillin-resistant Staphylococcus aureus clinical isolates from animals in New Zealand, 2012-2013, and subclinical colonisation in dogs and cats in Auckland

AIMS

To characterise methicillin-resistant Staphylococcus aureus (MRSA) isolates from infection sites in animals in New Zealand and assess the prevalence of subclinical MRSA colonisation in dogs and cats attending veterinary clinics in Auckland.

METHODS

MRSA isolates from clinical specimens obtained by the main New Zealand veterinary diagnostic laboratories between June 2012 and June 2013, were genotypically characterised by DNA microarray hybridisation analysis and spa typing. In addition, nasal or perineal skin swabs collected from a cross-sectional sample of dogs (n=361) and cats (n=225) attending 29 veterinary clinics in Auckland during the same period were analysed for MRSA by culture.

RESULTS

Eight MRSA clinical isolates were submitted for characterisation by the participating laboratories. The isolates originated from five dogs, including two isolates from the same dog, one foal, and one isolate had no identification of the source. The strain-types identified were AK3 (ST-5 SCCmecIV t045; n=1), USA500 (ST8 SCCmecIV t064; n=1), WSPP (ST30 SCCmecIV t019; n=1), Rhine Hesse (ST5 SCCmecII t002; n=2), and EMRSA-15 (ST22 SCCmecIV t032; n=3). No MRSA were isolated from 586 cultured swabs. Methicillin-susceptible S. aureus were detected in 9/257 (3.5%) swabs and non-aureus staphylococci in 22/257 (8.5%) swabs. The estimated true MRSA subclinical colonisation prevalence was 0%, with an upper 95% CI boundary of 1.9% for cats and 1.4% for dogs.

CONCLUSIONS

The modest number of MRSA isolates submitted for this study by the participating laboratories suggests clinical MRSA infection in animals in New Zealand continues to be sporadic. The wide variety of strain-types found mirrored the evolving strain-type diversity observed in humans. We cannot rule out bias due to the non-random sampling of dogs and cats, but the apparent colonisation prevalence of 0% was consistent with the low prevalence of subclinical colonisation in humans in New Zealand. These similarities indicate the epidemiology of animal and human MRSA infections are linked.

CLINICAL RELEVANCE

In the last decade, the prevalence of human MRSA infections in New Zealand has steadily increased. This is the second published study of MRSA in animals in New Zealand. The results indicate clinical MRSA infection in animals remains sporadic, but the diversification of the strain-types may pose new therapeutic challenges to veterinarians, due to their diverse resistome.

An evaluation of matrix-assisted laser desorption ionization time-of-flight mass spectrometry for the identification of Staphylococcus pseudintermedius isolates from canine infections

It has been proposed, based on taxonomic and molecular studies, that all canine isolates belonging to Staphylococcus intermedius group (SIG) should be renamed Staphylococcus pseudintermedius. However, isolates of SIG and other coagulase-positive staphylococci share many phenotypic characteristics, which could lead to misidentification. The accuracy of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identifying S. pseudintermedius isolates obtained from canine infections was evaluated, using a polymerase chain reaction (PCR)-based identification as the gold standard. In addition, MALDI-TOF MS was compared with conventional biochemical tests. A central problem was the incorrect identification of S. pseudintermedius isolates as S. intermedius by either MALDI-TOF MS or biochemical identification. From the 49 S. pseudintermedius isolates identified by the molecular method, only 21 could be assigned to this species by the biochemical approach and only 12 by MALDI-TOF MS. The 6 S. aureus isolates were correctly identified by all 3 techniques. However, using biochemical tests, 9 S. pseudintermedius were mistakenly classified as S. aureus, indicating a reduced specificity relative to the MALDI-TOF MS system. Analysis with the MALDI-TOF MS platform allowed rapid and accurate identification of the 49 isolates to the S. intermedius group but the approach was very limited in identifying S. pseudintermedius isolates, as only 12 of 49 isolates were correctly identified, a sensitivity of 0.24 (95% confidence interval: 0.13-0.39).