Antimicrobial use guidelines for canine pyoderma by the International Society for Companion Animal Infectious Diseases (ISCAID)

BACKGROUND

Canine pyoderma is one of the most common presentations in small animal practice, frequently leading to antimicrobial prescribing.

OBJECTIVES

To provide clinicians with antimicrobial treatment guidelines for staphylococcal pyoderma, including those involving meticillin-resistant staphylococci. Guidance on diagnosing surface, superficial and deep pyoderma and their underlying primary causes, is included. Recommendations aim to optimise treatment outcomes while promoting responsible antimicrobial use.

MATERIALS AND METHODS

Evidence was gathered from a systematic literature review of English-language treatment studies for canine pyoderma up to 23 December 2023. Quality was assessed using SORT criteria and combined with authors' consensus evaluation. Recommendations were voted on in an iterative process, followed by a Delphi-style feedback process before final agreement by the authors.

RESULTS

Cytology should be performed in all cases before antimicrobials are used. Topical antimicrobial therapy alone is the treatment-of-choice for surface and superficial pyodermas. Systemic antimicrobials should be reserved for deep pyoderma and for superficial pyoderma when topical therapy is not effective. Systemic therapy, with adjunctive topical treatment, is initially provided for 2 weeks in superficial and 3 weeks in deep pyoderma, followed by re-examination to assess progress and manage primary causes. First-choice drugs have expected efficacy against the majority of meticillin-susceptible Staphylococcus pseudintermedius; for all other drugs, laboratory testing should confirm susceptibility and exclude suitability of safer alternatives. As culture and susceptibility testing are essential for rationalising systemic therapy, laboratories and practices should price them reasonably to encourage use. Proactive topical therapy using antiseptics may help prevent recurrences.

CONCLUSIONS AND CLINICAL RELEVANCE

The accessibility of the skin offers excellent, achievable opportunities for antimicrobial stewardship.

Comparative study of a commercial formula containing natural antimicrobials versus oral cephalexin or topical chlorhexidine-miconazole therapies for treating superficial pyoderma in dogs

BACKGROUND

Chronic and recurrent pyoderma in dogs is driving a growing interest in natural antimicrobial products that offer minimal adverse effects and avoid antibiotic resistance.

OBJECTIVES

Evaluate the safety and efficacy of dermatological products with antimicrobial peptides and plant extracts, comparing them to chlorhexidine + miconazole and cephalexin therapy for superficial pyoderma in dogs.

MATERIALS AND METHODS

Forty-five dogs with superficial pyoderma underwent clinical, cytopathological and microbiological diagnosis, and were randomly assigned to Group 1 (G1) treated with shampoo (two weekly baths) and lotion (twice daily on the affected areas) containing natural antimicrobials; Group 2 (G2) treated with two weekly baths using a therapeutic shampoo containing 2% chlorhexidine and 2.5% miconazole; or Group 3 (G3) treated with oral cephalexin 30 mg/kg twice daily. Staphylococcus spp. strains were identified using matrix-assisted laser desorption ionisation-time of flight mass spectrometry and pruritus Visual Analog Scale (PVAS)/lesion scores were evaluated on Day (D)0, D7, D14, D21 and D28.

RESULTS

Statistical differences (p < 0.05) were noted between D0 and D28 in PVAS values and lesion scores for all groups. G1 had lower PVAS scores than other groups on D7 and D14 (p < 0.05) and lower lesion scores than G3 on D7. By D28, G1 and G3 had lower lesion scores than G2. Notably, G1 and G2 had no adverse effects, while 26% of G3 patients experienced gastrointestinal issues during therapy.

CONCLUSIONS AND CLINICAL RELEVANCE

This preliminary investigation of the new product (G1) suggests that it is effective, safe and a promising topical treatment for managing superficial pyoderma in dogs, offering an alternative to systemic antibiotics and topical antiseptic treatments.

Erythritol alters phosphotransferase gene expression and inhibits the in vitro growth of Staphylococcus coagulans isolated from canines with pyoderma

Staphylococcus coagulans (SC) belongs to a group of coagulase-positive staphylococci occasionally isolated from the skin lesions of dogs with pyoderma. We recently revealed that erythritol, a sugar alcohol, inhibited the growth of SC strain JCM7470. This study investigated the molecular mechanisms involved in this growth inhibition of JCM7470 by erythritol, and determine whether erythritol inhibits the growth of SC isolated from the skin of dogs with pyoderma. Comprehensive analysis of the gene expression of JCM7470 in the presence of erythritol revealed that erythritol upregulated the expression of glcB and ptsG genes, both of which encode phosphotransferase system (PTS) glucoside- and glucose-specific permease C, B, and A domains (EIICBA), respectively, associated with sugar uptake. Moreover, erythritol suppressed in vitro growth of all 27 SC strains isolated from the skin lesions of canine pyoderma, including 13 mecA gene-positive and 14 mecA gene-negative strains. Finally, the growth inhibition of the SC clinical isolates by erythritol was restored by the addition of glucose. In summary, we revealed that erythritol promotes PTS gene expression and suppresses the in vitro growth of SC clinical isolates from dogs with pyoderma. Restoration of the erythritol-induced growth inhibition by glucose suggested that glucose starvation may contribute to the growth inhibition of SC.

High prevalence of Panton-Valentine Leucocidin among Staphylococcus coagulans isolated from dogs in Rio de Janeiro

AIMS

The purpose of this study was to characterize the capacity for biofilm formation, antimicrobial resistance rates, and search for genetic determinants of resistance and virulence in the species.

METHODS AND RESULTS

Strains were collected from asymptomatic and infected dogs. Identification was conducted using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF), antimicrobial susceptibility using disk diffusion and PCR targeting mecA. Biofilm formation was evaluated on a microtiter plate assay. A total of 27 strains were selected for whole-genome sequencing. We identified 111 Staphylococcus coagulans. The highest number was obtained from infected dogs. The highest resistance rates were observed for penicillin, gentamicin, and ciprofloxacin/erythromycin. Twelve strains were characterized as resistant to methicillin. All isolates had the ability to form biofilm and were strong producers. Among Methicillin Resistant Staphylococcus coagulans (MRSC), SCCmec types IIIA, and Vc were identified. Acquired resistance genes, such as aac(6')-aph(2''), tet(K), blaZ, qacG, qacJ, and erm(C) were found. Different virulence genes were identified. Of note, Panton-Valentine Leucocidin was highly prevalent among the isolates.

CONCLUSION

Staphylococcus coagulans had a high isolation rate among infected dogs and demonstrated significant resistance to commonly used antibiotics such as penicillin and gentamicin.

A review of cutaneous hypersensitivity reactions in dogs: A diagnostician's guide to allergy

Allergic dermatoses are common in people and domestic animals. Resultant lesions are routinely biopsied and submitted for histological examination to confirm a diagnosis or rule out diseases with overlapping or atypical clinical features. Diagnostic pathologists and clinicians are often faced with the difficult task of determining whether an allergic reaction pattern is present on both the microscopic and macroscopic levels and correlating histopathologic findings with clinical and historical data to achieve a precise clinical diagnosis. The bulk of the current veterinary literature on allergic dermatoses focuses on atopic dermatitis in dogs, distantly followed by cats, horses, and other animals. The objectives of this review are to demonstrate the key histopathologic and clinical diagnostic features of the various allergy-mediated reaction patterns, and to provide diagnosticians with a practical guide for clinicopathological correlations. Current concepts in the pathophysiology of immediate hypersensitivity reactions, with a focus on atopic dermatitis, are discussed. Points of potential histopathologic overlap between the "classic" allergic reaction pattern and less common inflammatory, predominately eosinophilic, conditions that may mimic this pattern will be discussed with the goal of highlighting the critical need for collaboration between pathologists and clinicians in furthering patient care.

Virulence Mechanisms of Staphylococcal Animal Pathogens

Staphylococci are major causes of infections in mammals. Mammals are colonized by diverse staphylococcal species, often with moderate to strong host specificity, and colonization is a common source of infection. Staphylococcal infections of animals not only are of major importance for animal well-being but have considerable economic consequences, such as in the case of staphylococcal mastitis, which costs billions of dollars annually. Furthermore, pet animals can be temporary carriers of strains infectious to humans. Moreover, antimicrobial resistance is a great concern in livestock infections, as there is considerable antibiotic overuse, and resistant strains can be transferred to humans. With the number of working antibiotics continuously becoming smaller due to the concomitant spread of resistant strains, alternative approaches, such as anti-virulence, are increasingly being investigated to treat staphylococcal infections. For this, understanding the virulence mechanisms of animal staphylococcal pathogens is crucial. While many virulence factors have similar functions in humans as animals, there are increasingly frequent reports of host-specific virulence factors and mechanisms. Furthermore, we are only beginning to understand virulence mechanisms in animal-specific staphylococcal pathogens. This review gives an overview of animal infections caused by staphylococci and our knowledge about the virulence mechanisms involved.

Prevalence of multidrug-resistant coagulase-positive staphylococci in canine and feline dermatological patients over a 10-year period: a retrospective study

Coagulase-positive staphylococci (CPS) are common cutaneous pathogens often requiring multiple courses of antibiotics, which may facilitate selection for methicillin-resistant (MR) and/or multidrug-resistant (MDR) strains. To determine the prevalence of canine and feline MR/MDR CPS associated with skin diseases, medical records were retrospectively searched from April 2010 to April 2020. Pets with at least one positive culture for CPS were selected. Age, sex, antimicrobial sensitivity, previous history of antimicrobial/immunomodulatory medications and methicillin resistance/multidrug resistance status were recorded. Staphylococcus pseudintermedius (SP) (575/748) and Staphylococcus schleiferi (SS) (159/748) in dogs, and Staphylococcus aureus (12/22) in cats, were the most common CPS isolated. Three hundred and twenty-three out of 575 isolates were MR-SP (56.2 %), 304/575 were MDR-SP (52.8 %), 100/159 were MR-SS (62.9 %) and 71/159 were MDR-SS (44.6 %). A trend analysis showed a significant increase of resistance to oxacillin and chloramphenicol for S. pseudintermedius (r=0.86, 0.8; P=0.0007, 0.0034, respectively). Major risk factors for MDR-SP included oxacillin resistance (OR: 3; 95 % CI: 1.4-6.5; P=0.0044), positivity for PBP2a (OR: 2.3; 95 % CI: 1-5; P=0.031) and use of antibiotics in the previous year (OR: 2.8; 95 % CI: 1.3-5.8; P=0.0071). Oxacillin resistance was identified as a major risk factor for MDR-SS (OR: 8.8; 95 % CI: 3.6-21.1; P<0.0001). These results confirmed the widespread presence of MR/MDR CPS in referred dermatological patients. Judicious antibiotic use, surveillance for MR/MDR infections and consideration of alternative therapies are crucial in mitigating the development of resistant strains.

Evolution of the Prevalence of Antibiotic Resistance to Staphylococcus spp. Isolated from Horses in Florida over a 10-Year Period

Previous studies documented antibiotic resistance in horses but did not focus on skin specifically. We investigated antibiotic resistance and correlations between resistance patterns in skin infections. Records from 2009 to 2019 were searched for Staphylococcal infection and susceptibility results. Seventy-seven cases were included. Organisms identified were S. aureus (48/77), S. pseudintermedius (7/77), non-hemolytic Staphylococcus (8/77), beta-hemolytic Staphylococcus (6/77), and other species (8/77). Samples included pyoderma (36/77), wounds (10/77), abscesses (15/77), incision sites (5/77), nose (8/77), and foot (3/77). A trend analysis using non-parametric Spearman's test showed significant upward trend of resistance (p < 0.05) for 3/15 antibiotics (ampicillin, cefazolin, penicillin). Susceptibility was significantly different by Staphylococcal species for 8/15 antibiotics. Gentamicin showed significant susceptibility differences based on source (all abscesses were susceptible to gentamicin). Steel-Dwass test showed statistically significant (p = 0.003) difference between incision sites and abscesses. A non-parametric Kendall's T-test found significantly negative correlation between cefazolin and amikacin sensitivity (p = 0.0108) and multiple positive correlations of resistance (p < 0.05). This study confirms increasing resistance in dermatologic samples. It is unlikely that the sample source affects resistance, but Staphylococcus species may affect it. Study limitations include lack of information about previous antibiotic use and small sample size.

An epidemiological study of the predictors of multidrug resistance and methicillin resistance among Staphylococcus spp. isolated from canine specimens submitted to a diagnostic laboratory in Tennessee, USA

Background

Understanding drivers of multidrug resistance (MDR) and methicillin resistance, which have increased among canine staphylococcal isolates, is essential for guiding antimicrobial use practices. Therefore, the objective of this study was to identify predictors of MDR and methicillin resistance among Staphylococcus spp. commonly isolated from canine clinical specimens.

Methods

This retrospective study used records of canine specimens submitted to the University of Tennessee College of Veterinary Medicine Clinical Bacteriology Laboratory for bacterial culture and antimicrobial susceptibility testing between 2006 and 2017. Records from 7,805 specimens positive for the following Staphylococcus species were included for analysis: Staphylococcus pseudintermedius, Staphylococcus aureus, Staphylococcus coagulans (formerly Staphylococcus schleiferi subspecies coagulans), and Staphylococcus schleiferi (formerly S. schleiferi subsp. schleiferi). Generalized linear regression models were fit using generalized estimating equations (GEE) to identify predictors of MDR (defined as resistance to three or more antimicrobial classes) and methicillin resistance among these isolates.

Results

Multidrug resistance (42.1%) and methicillin resistance (31.8%) were relatively common. Isolates from skeletal (joint and bone) specimens had the highest levels of MDR (51.3%) and methicillin resistance (43.6%), followed by cutaneous specimens (45.8% multidrug-resistant, 37.1% methicillin resistant). Staphylococcus species, specimen site, and clinical setting were significant (p < 0.01) predictors of both outcomes. Compared to S. pseudintermedius, S. schleiferi had higher odds of methicillin resistance, while S. coagulans and S. schleiferi had lower odds of MDR. The odds of both MDR and methicillin resistance for isolates from hospital patient specimens were significantly higher than those from referral patients for urine/bladder and otic specimens. Odds of MDR among isolates from skeletal specimens of hospital patients were also higher than those of referral patients.

Conclusions

Staphylococcus isolates in this study had substantial levels of MDR and methicillin resistance. Differences in the odds of these outcomes between referral and hospital patient isolates did not persist for all specimen sites, which may reflect differences in diagnostic testing and antimicrobial use practices with respect to body site or system. Judicious antimicrobial use, informed by culture and susceptibility testing, is important to limit treatment failures and curb selection pressure.

Staphylococcus schleiferi subspecies coagulans septic shock in an immunocompetent male following canine otitis externa

Staphylococcus schleiferi bacteremia is an underappreciated cause of septic shock in the critical care department. Although nominally a coagulase variable Staphylococcus and associated with otitis externa infections in canine species, it has been associated with the metastatic infection including osteomyelitis, endocarditis, nephritis, and meningitis in humans. This report records a possible zoonotic case of S. schleiferi subspecies coagulans bacteremia following canine otitis externa associated with septic shock and endovascular infection precipitating intensive care admission for vasopressor support in an immunocompetent male.

Fluorescent Light Energy in the Management of Multi Drug Resistant Canine Pyoderma: A Prospective Exploratory Study

The increase in prevalence of staphylococcal antimicrobial resistance has been also associated with pyoderma in dogs, and prolonged antibiotic treatment, as often needed in severe cases of pyoderma, has been related to influencing possible development of multidrug resistance (MDR). Fluorescent light energy (FLE) has been indicated to improve pyoderma lesions as adjunct therapy to systemic antibiotics. In the present study, we evaluated the effect of FLE on clinical signs of MDR canine deep pyoderma (CDP) and interdigital furunculosis (CIF) when administered as solely management. Sixteen client-owned dogs affected by CIF (five dogs) and CDP (eleven dogs) were scored using a dedicated scoring system and received a single FLE applications twice weekly, until clinical resolution was achieved. Mean time to achieve complete resolution was 5.20 ± 3.56 weeks (median 3 weeks) for CIF cases and 4.18 ± 1.47 weeks (median 4 weeks) for CDP ones. FLE shows promise as an aid to managing clinical signs while reducing reliance on antibiotics for MDR CDP and CIF. In this study, FLE was responsible for the decrease in lesion scores and resolution of MDR pyoderma infection without any adjunct therapy, having a potential useful role to play in antibiotic stewardship programs, efficiently promoting complete clinical resolution of MDR lesions while optimizing the use of antibiotics.

Patterns of antimicrobial, multidrug and methicillin resistance among Staphylococcus spp. isolated from canine specimens submitted to a diagnostic laboratory in Tennessee, USA: a descriptive study

Background

Multidrug- and methicillin-resistant staphylococci are both veterinary and public health concerns due to their zoonotic potential. Therefore, the objective of this study was to investigate patterns of antimicrobial, multidrug, and methicillin resistance among four Staphylococcus spp. commonly isolated from canine clinical specimens submitted to the Clinical Bacteriology Laboratory at the University of Tennessee College of Veterinary Medicine (UTCVM).

Methods

Results of antimicrobial susceptibility testing and mecA polymerase chain reaction (PCR) for isolates of four common Staphylococcus spp. isolates were obtained from the Bacteriology Laboratory at the UTCVM between 01/01/2006 and 12/31/2017. Cochran-Armitage trend test was used to assess temporal trends of antimicrobial resistance (AMR), multidrug resistance (MDR), and methicillin resistance. Kappa test of agreement was used to assess agreement between the results of PCR and disk diffusion tests.

Results

Most of the 7805 isolates were S. pseudintermedius (6453 isolates), followed by S. coagulans (860), S. aureus (330), and S. schleiferi (162). Among S. pseudintermedius isolates, 45.5% were MDR, and 30.8% were methicillin-resistant (MRSP). There was a significant temporal increase in MRSP (p = 0.017). Chloramphenicol resistance increased among both MRSP and methicillin-susceptible (MSSP) isolates (p <  0.0001). Among S. aureus isolates, 40.9% were MDR, 37.4% were methicillin-resistant (MRSA), and the proportion of MRSA isolates increased significantly (p = 0.0480) over time. There was an increasing temporal trend in the proportion of MDR isolates among MSSP (p = 0.0022), but a decrease among MRSP (p <  0.0001) and MRSA (p = 0.0298). S. schleiferi had the highest percentage (56.9%) of methicillin-resistant isolates. Oxacillin disk diffusion was superior to cefoxitin for the detection of mecA-mediated resistance and had almost perfect agreement with mecA PCR assay for S. pseudintermedius (95.4% agreement, kappa (κ) = 0.904; p <  0.0001), S. coagulans (95.6%, κ = 0.913; p <  0.0001) and S. schleiferi (97.7%, κ = 0.945; p <  0.0001). However, cefoxitin disk diffusion was superior to oxacillin disk diffusion and had almost perfect agreement with mecA PCR assay for S. aureus (95.3%, κ = 0.834; p <  0.0001).

Conclusions

The levels of resistance and increasing temporal trends are concerning. These findings have implications for treatment decisions and public health due to the zoonotic potential of staphylococci. Continued surveillance and use of antibiograms to guide clinical decisions will be critical.

Effect of topical medication on the nasomaxillary skin-fold microbiome in French bulldogs

BACKGROUND

Host-microbe interactions may influence dermatitis pathogenesis in the nasomaxillary folds of French bulldogs, which is often complicated by secondary bacterial and fungal infections.

OBJECTIVE

To assess the skin-fold microbiome in systemically healthy French bulldogs and to determine the influence of topical medications on this microbiome.

ANIMALS

Nineteen healthy French bulldogs.

METHODS AND MATERIALS

Next-generation DNA sequencing was applied to characterise the microbiome composition in the nasomaxillary folds of systemically healthy French bulldogs. Subsequently, the effect of two topical products on the fold microbiome was assessed. Seven dogs were treated with a protease product (Kalzyme; enzyme) that inhibits biofilm formation without biocidal activity, six dogs were treated with a 2% chlorhexidine diacetate solution (Nolvasan; CHX) with biocidal activity, and six dogs were untreated. Dogs were randomly assigned to each group, and the investigator was blinded.

RESULTS

The primary skin bacterial phyla inhabiting the folds at inclusion were Firmicutes, Actinobacteria and Proteobacteria. The primary skin fungal phyla were Ascomycota and Basidiomycota. Topical treatment increased the diversity of bacterial and fungal compositions over time (increase in microbial diversity score: enzyme 38%, chlorhexidine 11%, control <5%) and the relative abundance of pathogens reduced significantly (enzyme, P = 0.028; CHX, P = 0.048). A clear correlation (r²  = 0.83) was observed between the abundance of clinically relevant pathogens and microbial diversity.

CONCLUSIONS

The nasomaxillary skin-fold microbiome of healthy French bulldogs contained a high abundance of clinically relevant pathogens (mean 36.4%). Topical therapy with enzyme increased microbial diversity of skin folds and reduced the relative abundance of pathogens.

First human case of catheter-related blood stream infection caused by Staphylococcus schleiferi subspecies coagulans: a case report and literature review

BACKGROUND

Staphylococcus schleiferi is a gram-positive pathogenic coccus which causes canine skin and ear infections. Only four cases of human infection caused by Staphylococcus schleiferi subspecies coagulans have been reported. Herein, we present the first case of catheter-related bloodstream infection caused by S. schleiferi subspecies coagulans.

CASE PRESENTATION

A 62-year-old Japanese man was admitted to our hospital for examination of sigmoid colon tumor. During hospitalization, he had fever, shaking chills, and swelling at the peripheral venous catheter insertion site. Two sets of blood cultures were positive for S. schleiferi subspecies coagulans which was confirmed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), 16S ribosomal RNA sequencing and the coagulase test. The patient was successfully treated without relapse.

CONCLUSION

To our knowledge, this is the first report of catheter-related bloodstream infection caused by S. schleiferi subspecies coagulans. S. schleiferi subsp. coagulans can be pathogenic in humans, and MALDI-TOF MS can contribute to accurate identification of S. schleiferi subspecies coagulans.

EFSA Panel on Animal Health and Welfare (AHAW), Nielsen SS, Bicout DJ, Calistri P, Canali E, Drewe JA, Garin‐Bastuji B, Gonzales Rojas JL, Gortazar Schmidt C, Herskin M, Michel V, Miranda Chueca MA, Padalino B, Pasquali P, Roberts HC, Sihvonen LH, Spoolder H, Stahl K, Velarde A, Viltrop A, Winckler C, Guardabassi L, Hilbert F, Mader R, Aznar I, Baldinelli F, Alvarez J. Assessment of animal diseases caused by bacteria resistant to antimicrobials: Dogs and cats

In this opinion the antimicrobial-resistant bacteria responsible for transmissible diseases that constitute a threat to dog and cat health have been assessed. The assessment has been performed following a methodology based on information collected via an extensive literature review and expert judgement. Details of the methodology used for this assessment are explained in a separate opinion. A global state of play of antimicrobial resistant Staphylococcus pseudintermedius, Staphylococcus aureus, Staphylococcus schleiferi, Escherichia coli, Proteus mirabilis, Klebsiella spp., Enterobacter spp., Pseudomonas aeruginosa, Clostridium perfringens, Clostridioides difficile, Enterococcus faecalis and Enterococcus faecium has been provided. Among those bacteria, EFSA identified S. pseudintermedius, E. coli and P. aeruginosa with > 90% certainty as the most relevant antimicrobial resistant bacteria in the EU based on the available evidence. The animal health impact of these most relevant bacteria, as well as their eligibility for being listed and categorised within the animal health law framework will be assessed in separate scientific opinions.

Phenotypic and Molecular Traits of Staphylococcus coagulans Associated with Canine Skin Infections in Portugal

Staphylococcus coagulans is among the three most frequent pathogens of canine pyoderma. Yet, studies on this species are scarce. Twenty-seven S. coagulans and one S. schleiferi, corresponding to all pyoderma-related isolations from these two species at two veterinary laboratories in Lisbon, Portugal, between 1999 and 2018 (Lab 1) or 2018 (Lab 2), were analyzed. Isolates were identified by the analysis of the nuc gene and urease production. Antibiotic susceptibility towards 27 antibiotics was evaluated by disk diffusion. Fourteen antibiotic resistance genes were screened by PCR. Isolates were typed by SmaI-PFGE. Two S. coagulans isolates (2/27, 7.4%) were methicillin-resistant (MRSC, mecA+) and four (4/27, 14.8%) displayed a multidrug-resistant (MDR) phenotype. We observed resistance to penicillin (17/27, 63.0%), fluoroquinolones (11/27, 40.7%), erythromycin and clindamycin (3/27, 11.1%), fusidic acid (3/27, 11.1%) and tetracycline (1/27, 3.7%). The blaZ and erm(B) genes were carried by 16 and 1 isolates resistant to penicillin and erythromycin/clindamycin, respectively. Only three S. coagulans carried plasmids. The single S. schleiferi isolate presented an MDR phenotype. SmaI-PFGE revealed a limited genetic diversity of S. coagulans, with a predominant lineage present from 2001 to 2018. This study describes the first MRSC causing canine infection in Portugal and reveals a high burden of antimicrobial resistance, with the emergence of MDR phenotypes within the main lineages.

Complete genome sequence of a methicillin-resistant Staphylococcus schleiferi strain from canine otitis externa in Korea

The increase in canine skin and soft tissue infections, such as pyoderma and otitis, caused by Staphylococcus schleiferi strains, is of significant zoonotic concern. In this study, we report the first complete genome sequence for a methicillin-resistant clinical isolate of S. schleiferi (MRSS) designated as SS4, obtained from a dog with otitis externa, in Korea. The genome of SS4 strain was of 2,539,409 bp and presented high G+C content ratio (35.90%) with no plasmid. Comparative analysis of SS4 genome revealed that it is closely related to 2142-05 and 5909-02 strains isolated from the canine skin infections in the USA.

Commensal Staphylococci Including Methicillin-Resistant Staphylococcus aureus from Dogs and Cats in Remote New South Wales, Australia

Staphylococci are important opportunistic pathogens in human and veterinary medicine in addition to being part of the normal flora of the skin and mucous membranes of mammals and birds. The rise of antimicrobial resistance amongst staphylococci warrants closer investigation of the diversity of skin commensal organisms-including coagulase-negative staphylococci (CoNS)-due to their potential as a source of resistance genes. This study is aimed at characterising the commensal staphylococci-including methicillin-resistant Staphylococcus species (spp.)-from mucocutaneous sites of dogs and cats from remote New South Wales (NSW), Australia. Pet dogs and cats were recruited from participants in a community companion animal health programme in six communities in western NSW. Three swabs were collected from each animal (anterior nares, oropharynx, and perineum) and from skin lesions or wounds if present and cultured on selective media for Staphylococcus spp. In total, 383 pets (303 dogs, 80 cats) were enrolled. Staphylococcus spp. were isolated from 67.3% of dogs and 73.8% of cats (494 isolates). The diversity of CoNS was high (20 species) whilst only three coagulase-positive spp. were isolated (S. pseudintermedius, S. aureus, S. intermedius). The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) carriage in dogs was high (2.6%) relative to other studies but was only a small proportion of overall commensal staphylococci. No cats carried MRSA and no MRSP was isolated from either species. Dogs were significantly more likely to carry coagulase-positive staphylococci than cats (P < 0.001). Amongst dogs, males and those with skin lesions were more likely to carry S. pseudintermedius. This study highlights important differences in the diversity and patterns of carriage of commensal staphylococci between dogs and cats in remote NSW, Australia.

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.

Evaluation of Oxacillin and Cefoxitin Disk Diffusion and MIC Breakpoints Established by the Clinical and Laboratory Standards Institute for Detection of mecA-Mediated Oxacillin Resistance in Staphylococcus schleiferi

Staphylococcus schleiferi is a beta-hemolytic, coagulase-variable colonizer of small animals that can cause opportunistic infections in humans. In veterinary isolates, the rate of mecA-mediated oxacillin resistance is significant, with reported resistance rates of >39%. The goal of this study was to evaluate oxacillin and cefoxitin disk diffusion (DD) and MIC breakpoints for detection of mecA-mediated oxacillin resistance in 52 human and 38 veterinary isolates of S. schleiferi Isolates were tested on multiple brands of commercial media and according to Clinical and Laboratory Standards Institute (CLSI) methods. Zone diameters and MIC values were interpreted using CLSI breakpoints (CLSI, Performance Standards for Antimicrobial Susceptibility Testing. M100-S27, 2017) for Staphylococcus aureus/Staphylococcus lugdunensis, coagulase-negative staphylococci (CoNS), and Staphylococcus pseudintermedius Results were compared to those of mecA PCR. Twenty-nine of 90 (32%) isolates were mecA positive. Oxacillin inhibition zone sizes and MICs interpreted by S. pseudintermedius breakpoints reliably differentiated mecA-positive and mecA-negative isolates, with a categorical agreement (CA) of 100% and no very major errors (VMEs) or major errors (MEs) for all media. For cefoxitin DD results interpreted using S. aureus/S. lugdunensis and CoNS breakpoints, CA values were 85% and 75%, respectively, and there were 72% and 64% VMEs, respectively, and 0 MEs. For cefoxitin MICs interpreted using S. aureus/S. lugdunensis breakpoints, CA was 81%, and there were 60% VMEs and no MEs. Our data demonstrate that oxacillin DD or MIC testing methods using the current S. pseudintermedius breakpoints reliably identify mecA-mediated oxacillin resistance in S. schleiferi, while cefoxitin DD and MIC testing methods perform poorly.

Divergent Isoprenoid Biosynthesis Pathways in Staphylococcus Species Constitute a Drug Target for Treating Infections in Companion Animals

Drug-resistant Staphylococcus species are a major concern in human and veterinary medicine. There is a need for new antibiotics that exhibit a selective effect in treating infections in companion and livestock animals and that would not be used to treat human bacterial infections. We have identified fosmidomycin as an antibiotic that selectively targets certain Staphylococcus species that are often encountered in skin infections in cats and dogs. These findings expand our understanding of Staphylococcus evolution and may have direct implications for treating staphylococcal infections in veterinary medicine.

Staphylococcus species are a leading cause of skin and soft tissue infections in humans and animals, and the antibiotics used to treat these infections are often the same. Methicillin- and multidrug-resistant staphylococcal infections are becoming more common in human and veterinary medicine. From a “One Health” perspective, this overlap in antibiotic use and resistance raises concerns over the potential spread of antibiotic resistance genes. Whole-genome sequencing and comparative genomics analysis revealed that Staphylococcus species use divergent pathways to synthesize isoprenoids. Species frequently associated with skin and soft tissue infections in companion animals, including S. schleiferi and S. pseudintermedius, use the nonmevalonate pathway. In contrast, S. aureus, S. epidermidis, and S. lugdunensis use the mevalonate pathway. The antibiotic fosmidomycin, an inhibitor of the nonmevalonate pathway, was effective in killing canine clinical staphylococcal isolates but had no effect on the growth or survival of S. aureus and S. epidermidis. These data identify an essential metabolic pathway in Staphylococcus that differs among members of this genus and suggest that drugs such as fosmidomycin, which targets enzymes in the nonmevalonate pathway, may be an effective treatment for certain staphylococcal infections.

IMPORTANCE Drug-resistant Staphylococcus species are a major concern in human and veterinary medicine. There is a need for new antibiotics that exhibit a selective effect in treating infections in companion and livestock animals and that would not be used to treat human bacterial infections. We have identified fosmidomycin as an antibiotic that selectively targets certain Staphylococcus species that are often encountered in skin infections in cats and dogs. These findings expand our understanding of Staphylococcus evolution and may have direct implications for treating staphylococcal infections in veterinary medicine.

Prevalence and risk factors of Staphylococcus spp. carriage among dogs and their owners: A cross-sectional study

This study investigated colonization and association of staphylococci between healthy dogs and their owners. In a cross-sectional study, nasal carriage and antibiotic susceptibility of isolated staphylococci were determined for 119 dogs and 107 owners. Relatedness of the Staphylococcus isolates in dogs and their owners was investigated using antibiograms, toxin profiles, and genotyping by pulsed-field gel electrophoresis (PFGE), multilocus sequence type, and spa typing. Risk factors for carriage of methicillin-resistant staphylococci in dogs were also evaluated. Staphylococcus spp. were isolated from 65 (60.7%) owners and 44 (37.0%) dogs. The following species were isolated, listed in order of decreasing frequency: S. epidermidis, S. pseudintermedius, S. aureus, S. scheiferi subsp. coagulans, S. haemolyticus, S. sciuri, S. saprophyticus and S. warneri. S. pseudintermedius (65.9%) was the major isolate in dogs while S. epidermidis (81.5%) was the major type in owners. Among the isolates, 71.6% were methicillin resistant (MR) and 95.4% of the isolates demonstrated multi-drug resistance regardless of the origin. Only one dog-owner pair shared the same Staphylococcus spp. (S. pseudintermedius); however, the organisms were of different PFGE subtypes and exhibited different antibiotic resistance and toxin profiles while both isolates displayed same sequence type (ST365). While the dog-origin isolate showed spa type t02, the owner-origin isolate was negative to PCRs targeting spa gene sequence. Risk factor analysis showed that the presence of cohabitant animals was correlated with the nasal carriage of MR staphylococci in dogs. The cumulative data indicated that animal- and owner-origin staphylococci have various subtypes with high prevalence of MR; however, the bacteria are not shared between healthy dogs and their owners.

Genotypic relatedness and antimicrobial resistance of Staphylococcus schleiferi in clinical samples from dogs in different geographic regions of the United States

BACKGROUND

Staphylococcus schleiferi is a known pathogen that can cause canine skin and ear infections. The aim of this study was to determine the molecular epidemiology and antimicrobial susceptibility of clinical veterinary isolates from different geographic regions in the United States.

HYPOTHESIS

It was hypothesized that S. schleiferi would maintain genotypic homogeneity across the different geographic regions and that meticillin-resistant (MR) isolates of S. schleiferi would predominate.

METHODS

Isolates were identified as S. schleiferi by a commercial microbiology identification system and confirmed by nuc gene PCR. Antibiotic susceptibility data were collected and PBP2a latex agglutination testing was performed on MR isolates. Pulsed-field gel electrophoresis (PFGE) was performed and clonal clusters were identified with a Dice coefficient similarity of >80%.

RESULTS

There were 116 isolates from the Mid-Atlantic region and 101 from across the United States. Of these 217 isolates, 209 (96%) were obtained from cutaneous sites. Of the Mid-Atlantic isolates, 62% (72 of 116) were MR and 16% (18 of 116) were multidrug-resistant (MDR). Of the isolates from the other geographic regions, 73% (74 of 101) were MR and 24% (24 of 101) were MDR. All MR isolates were positive by PBP2a latex agglutination. PFGE identified 155 individual pulsed-field profiles and three major pulsed-field types (PFT) that contained 61% (133 of 217) of the isolates. These pulsed-field types were geographically heterogeneous.

CONCLUSIONS

This study demonstrates the dissemination of successful MR pulsed-field types of S. schleiferi across the United States.

The shared microbiota of humans and companion animals as evaluated from Staphylococcus carriage sites

BACKGROUND

Staphylococcus aureus and other coagulase-positive staphylococci (CPS) colonize skin and mucous membrane sites and can cause skin and soft tissue infections (SSTIs) in humans and animals. Factors modulating methicillin-resistant S. aureus (MRSA) colonization and infection in humans remain unclear, including the role of the greater microbial community and environmental factors such as contact with companion animals. In the context of a parent study evaluating the households of outpatients with community MRSA SSTI, the objectives of this study were 1) to characterize the microbiota that colonizes typical coagulase-positive Staphylococcus spp. carriage sites in humans and their companion pets, 2) to analyze associations between Staphylococcus infection and carriage and the composition and diversity of microbial communities, and 3) to analyze factors that influence sharing of microbiota between pets and humans.

RESULTS

We enrolled 25 households containing 56 pets and 30 humans. Sampling locations were matched to anatomical sites cultured by the parent study for MRSA and other CPS. Bacterial microbiota were characterized by sequencing of 16S ribosomal RNA genes. Household membership was strongly associated with microbial communities, in both humans and pets. Pets were colonized with a greater relative abundance of Proteobacteria, whereas people were colonized with greater relative abundances of Firmicutes and Actinobacteria. We did not detect differences in microbiota associated with MRSA SSTI, or carriage of MRSA, S. aureus or CPS. Humans in households without pets were more similar to each other than humans in pet-owning households, suggesting that companion animals may play a role in microbial transfer. We examined changes in microbiota over a 3-month time period and found that pet staphylococcal carriage sites were more stable than human carriage sites.

CONCLUSIONS

We characterized and identified patterns of microbiota sharing and stability between humans and companion animals. While we did not detect associations with MRSA SSTI, or carriage of MRSA, S. aureus or CPS in this small sample size, larger studies are warranted to fully explore how microbial communities may be associated with and contribute to MRSA and/or CPS colonization, infection, and recurrence.

Prevalence and risk factors for isolation of methicillin-resistant Staphylococcus in dogs with keratitis

OBJECTIVE

To determine the prevalence of, and risk factors for, methicillin-resistant Staphylococcus (MRS) isolation in dogs with naturally acquired bacterial keratitis.

PROCEDURES

All Staphylococcus spp. isolated from corneal samples of dogs with keratitis during a 2-year period were evaluated for methicillin resistance by bacteriologic methods. Each MRS isolate was subjected to in vitro susceptibility testing for systemic and ocular antimicrobials. Nasal swabs for culture were collected from all dogs with MRS corneal isolation to evaluate for nasal carrier status. Potential risk factors for MRS isolation were investigated by medical record review and administration of an epidemiological survey to dog owners. Collected information characterizing animal, client, and environmental variables was analyzed for association with MRS isolation.

RESULTS

Seventy-one Staphylococcus spp. were isolated from seventy individual dogs with keratitis during the study period. Seventeen of the Staphylococcus isolates (23.9%) were methicillin resistant. The MRS isolates included Staphylococcus epidermidis (n = 10), Staphylococcus pseudintermedius (n = 6), and Staphylococcus aureus (n = 1). The MRS corneal isolates displayed extensive antimicrobial resistance. Four dogs (23.5%) with MRS corneal isolates had positive nasal cultures for MRS. Client occupation was significantly (P = 0.01) associated with MRS isolation, and dogs belonging to owners employed in veterinary or human healthcare fields were four times more likely to have MRS keratitis than dogs owned by clients with different professions. There were no significant associations between the other evaluated animal, client, and environmental factors.

CONCLUSIONS

Methicillin resistance is relatively common in Staphylococcus isolates from dogs with corneal infections, particularly among dogs belonging to healthcare workers.

Prevalence of and risk factors for isolation of meticillin-resistant Staphylococcus spp. from dogs with pyoderma in northern California, USA

BACKGROUND

Canine pyodermas associated with meticillin-resistant Staphylococcus spp. (MRS) have increased in prevalence over the past decade.

HYPOTHESIS/OBJECTIVES

To compare the prevalence of MRS isolation from dogs with superficial pyoderma at a primary care clinic (PCC) and those at a tertiary care facility (VMTH) in California, USA, and identify associated risk factors.

ANIMALS

Client-owned dogs from the VMTH (80 dogs) and the PCC (30 dogs).

METHODS

Aerobic bacterial culture and antibiotic susceptibility were performed on swab specimens collected from dogs, and meticillin resistance was determined using microdilution methods according to Clinical and Laboratory Standards Institute guidelines. A mecA gene PCR assay was used to confirm meticillin resistance when possible.

RESULTS

Of 89 staphylococcal isolates from the VMTH, 34 (38.2%) were meticillin resistant. In 31 dogs, pyoderma persisted, and one or more follow-up isolates were obtained. The species isolated and drug susceptibility changed unpredictably during treatment. Of 33 PCC isolates, nine (27.3%) were meticillin resistant. Multiple drug resistance was identified in 41 of 53 (77.3%) MRS isolates from the VMTH and five of nine from the PCC. The sensitivity and specificity of PCR for the detection of meticillin resistance was 34 of 39 (87%) and 86 of 87 (99%), respectively. Risk factors for meticillin resistance for both sites were antibiotic treatment within the last year (P = 0.001), and for VMTH, hospitalization of dogs within the last year (P = 0.001).

CONCLUSIONS AND CLINICAL IMPORTANCE

The prevalence of meticillin resistance was not different between VMTH and PCC isolates (P = 0.29). Previous antimicrobial therapy was an important risk factor for the isolation of MRS at both sites.

Concentrations of clindamycin hydrochloride in homogenates of normal dog skin when administered at two oral dosage regimens

BACKGROUND

Clindamycin is frequently used for the treatment of bacterial pyoderma.

OBJECTIVE

To compare the pharmacokinetics of clindamycin in whole skin homogenates of normal dogs when administered orally at two dosage regimens (5.5 mg/kg BW, twice daily and 11 mg/kg BW, once daily).

ANIMALS AND METHODS

Skin biopsies were obtained from six laboratory beagles before, 3, 6 and 12 h after the first and the fifth dose of clindamycin at the former regimen, as well as before, 3, 6, 12 and 24 h after the first and third dose at the latter regimen. Tissue was homogenized and clindamycin concentrations were measured by reverse-phase high-performance liquid chromatography coupled with mass spectrometry. Results were analyzed using Student's t-test at a level of significance of 0.05.

RESULTS

Maximal concentration and area under the concentration-time curve, but not their relevant dose-normalized values, were higher at the dosage regimen of 11 mg/kg BW, once daily than at 5.5 mg/kg BW twice daily.

CONCLUSIONS

The pharmacokinetic profile of clindamycin is at least equal, if not better, when this antimicrobial is administered at 11 mg/kg BW, once daily.

Household transmission of meticillin-resistant Staphylococcus aureus and other staphylococci

Although the role of pets in household transmission of meticillin-resistant Staphylococcus aureus (MRSA) has been examined previously, only minor attention has been given to the role of the abiotic household environment independent of, or in combination with, colonisation of pets and human beings to maintain transmission cycles of MRSA within the household. This report reviews published work about household transmission of S aureus and other staphylococci and describes contamination of household environmental surfaces and colonisation of pets and people. Household microbial communities might have a role in transfer of antimicrobial resistance genes and could be reservoirs for recolonisation of people, although additional research is needed regarding strategies for decontamination of household environments. Household-based interventions should be developed to control recurrent S aureus infections in the community, and coordination between medical and veterinary providers could be beneficial.

Case-control study of Staphylococcus lugdunensis infection isolates from small companion animals

BACKGROUND

Coagulase-negative Staphylococcus lugdunensis has recently been shown to cause invasive infections of people, which are similar in pathogenic effect to those caused by Staphylococcus aureus. Little is known about the pathogenicity of S. lugdunensis in companion animals.

OBJECTIVES

To compare potential risk factors for infection, body sites affected, and whether cases and controls had been treated with antimicrobial drugs based upon susceptibility test results.

ANIMALS

Thirty-three cases of S. lugdunensis infection (25 dogs, six cats and two small mammals) were identified between January 2003 and August 2011. Two Staphylococcus pseudintermedius controls, which were identified by the microbiology laboratory immediately before and after each S. lugdunensis case, were host-species matched to each case.

METHODS

A retrospective case-control analysis.

RESULTS

During the period evaluated, the prevalence of S. lugdunensis infection was 1.3 cases per 10,000 hospital admissions for dogs and 0.95 cases per 10,000 admissions for cats (P = 0.453). In univariate analyses, S. pseudintermedius isolation was significantly associated with skin infections (P < 0.0001), while S. lugdunensis isolation was associated with the respiratory tract (P = 0.03) and other deep tissues (P = 0.005). Cases were less likely than controls to have been treated based upon susceptibility test results (P = 0.02). A conditional logistic regression analysis showed isolation of S. lugdunensis to be associated with recent (≤ 30 days) steroid administration (odds ratio, 17.72; 95% confidence interval, 2.35-132.82; P = 0.005); and in-patient status (odds ratio, 9.67; 95% confidence interval, 2.18-42.88; P = 0.003).

CONCLUSIONS

These results suggest that S. lugdunensis may cause invasive infections in companion animals, which should be treated with antimicrobials based upon susceptibility tests when available.

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.