Factors associated with methicillin-resistant versus methicillin-susceptible Staphylococcus pseudintermedius infection in dogs

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.

Risk factors for antimicrobial resistance among Staphylococcus isolated from pets living with a patient diagnosed with methicillin-resistant Staphylococcus aureus infection

It has been suggested that pets play a critical role in the maintenance of methicillin-resistant (MR) and multidrug-resistant (MDR) Staphylococcus spp. in the household. We examined risk factors for carriage of antimicrobial-resistant coagulase-positive staphylococci, with particular attention to Staphylococcus aureus and Staphylococcus pseudintermedius isolated from pets living in households of people diagnosed with methicillin-resistant S. aureus (MRSA) skin or soft-tissue infection. We analyzed data collected cross-sectionally from a study conducted in 2012 that evaluated the transmission of MRSA and other staphylococci from humans, their pets and the environment (Pets and Environmental Transmission of Staphylococci [PETS] study). We used unadjusted and adjusted stratified logistic regression analyses with household-clustered standard errors to evaluate the association between demographic, healthcare-related, contact-related and environmental risk factors and MDR Staphylococcus spp. isolated from dogs and cats. Staphylococcal isolates obtained from dogs (n = 63) and cats (n = 47) were included in these analyses. The use of oral or injectable antimicrobials by the pets during the prior year was the main risk factor of interest. Based on our results, 50% (12/24) of S. aureus, 3.3% (1/30) of S. pseudintermedius and 25% (14/56) of other coagulase-positive staphylococci (CPS) were determined to be MDR. S. aureus isolates were more likely to be MDR compared with S. pseudintermedius. We did not find a significant statistical association between the use of oral or injectable antimicrobials in the prior year and the presence of MDR bacteria. The results suggest that drivers of antimicrobial resistance in household staphylococci may vary by bacterial species, which could have implications for one health intervention strategies for staphylococci and inform the investigation of other reverse zoonoses, such as COVID-19.

Occurrence and characterization of methicillin-resistant Staphylococcus spp. in diseased dogs in Brazil

Staphylococcus pseudintermedius is a major commensal bacterium of the skin and mucosae of dogs and an opportunistic agent responsible for several clinical infections, such as pyoderma, otitis, and surgical wound infections. The emergence of methicillin-resistant S. pseudintermedius (MRSP) has become a problem of great concern in veterinary and human medicine because it is multidrug resistant (MDR) and can also infect humans. This study aimed to identify the occurrence of Staphylococcus spp. in infected patients and investigate the antimicrobial resistance profiles and molecular structure of MRSP isolates. Samples were obtained from two different veterinary clinics; suggestive colonies were submitted to matrix-assisted laser desorption ionization-time of flight (MALDI-ToF) mass spectrometry and confirmed at the species level by polymerase chain reaction (PCR). Sequencing of the 16S rRNA and rpoB genes were used in selected samples that were not identified by MALDI-ToF and by the species-specific PCR. Antimicrobial susceptibility and PCR detection of mecA were performed. MRSP isolates were subjected to multilocus sequence typing. Of all the clinical staphylococci (n = 131), 98 (74.8%) were identified as S. pseudintermedius. Multidrug resistance (resistance to ≥3 classes of antimicrobials) was observed in 63.2% of S. pseudintermedius isolates, and 24.5% of S. pseudintermedius isolates were methicillin-resistant. Half of the MRSP isolates were isolated from surgical site infections. Among the ten sequence types (ST) identified, nine were novel. ST71 was the most prevalent and associated with resistance to fluoroquinolones. Prior antimicrobial therapy, hospitalization, and surgical site infections seemed to be risk factors for MRSP acquisition. The present study showed a high rate of MDR staphylococci in infected dogs. MRSP was isolated from different clinical conditions, mainly surgical site infections. Additionally, this is the first study to extensively investigate the population structure of MRSP in Brazil, which revealed the dispersion of CC71 and nine novel ST. These findings raise concerns for both animal and human health due to the zoonotic potential of this species and limited therapeutic options available for MRSP infections.

Uncommon pathogens in an immunocompetent host: respiratory isolation of Cunninghamella bertholletiae, Aspergillus niger, Staphylococcus pseudintermedius and adenovirus in a patient with necrotising pneumonia

We present the unusual case of a 60-year-old immunocompetent woman with chronic obstructive pulmonary disease who developed a necrotising pneumonia with isolation of Cunninghamella bertholletiae, Aspergillus niger, Staphylococcus pseudintermedius and adenovirus. The patient recovered with antimicrobial therapy and supportive care in the intensive care unit. The current literature on diagnosis and treatment of these pathogens is reviewed.

Susceptibility to Bacteriocins of Multiresistant, mecA Gene Possessing Staphylococcus pseudintermedius Strains from Lesions on Dogs in Vojvodina (Serbia)

Aims: Staphylococci are considered commensal organisms; however, they can also cause diseases in animals. The species Staphylococcus pseudintermedius was originally isolated from the nares and anal mucosa of healthy dogs; nowadays, the incidence of methicillin-resistant S. pseudintermedius strains in dogs has increased, and this species has also become the most common cause of canine skin lesions. S. pseudintermedius were tested for their susceptibility to bacteriocins to show the potential of bacteriocins to eliminate/reduce S. pseudintermedius as a causative agent. Material and Methods: In this study, S. pseudintermedius were isolated from skin lesions on dogs of various breeds and ages in the Vojvodina region (Serbia) in the framework of our international co-operation. Results: S. pseudintermedius strains were identified using matrix-assisted laser desorption ionization time-of-flight mass spectrometry, and the species allocation was confirmed by genotypization and corroborated using phenotyping tests. The strains were multiresistant, involving methicillin-resistance. In addition, the mecA gene was detected in S. pseudintermedius strains, confirming the presence of a genetic feature for methicillin resistance. S. pseudintermedius strains produced large amounts of the enzymes alkaline phosphatase and acid phosphatase; they were low-grade biofilm forming (0.1 ≤ A₅₇₀ < 1.0), except S. pseudintermedius SPs1. All strains were susceptible to gallidermin (inhibition activity up to 204,800 arbitrary unit [AU]/mL); however, they were mostly resistant to enterocins. However, biofilm-forming S. pseudintermedius SPs1 was susceptible to enterocins (200 AU/mL). Conclusion: Establishing the susceptibility of multiresistant and mecA gene-possessing S. pseudintermedius strains to gallidermin is an innovative, original result; it provides a new opportunity for preventing/eliminating infection caused by those agents.

Prevalence of coagulase-positive methicillin-resistant Staphylococcus aureus and Staphylococcus pseudintermedius in dogs in Bangladesh

Background

The emergence of methicillin‐resistant Staphylococcus aureus (MRSA) and methicillin‐resistant Staphylococcus pseudintermedius (MRSP) have a significant health impact on people with direct or supportive occupations in veterinary medicine including veterinarians, animal handlers, laboratory personnel and pet owners.

Objectives

This cross‐sectional survey was conducted to determine the prevalence of and risk factors for S. aureus, S. pseudintermedius, MRSA and MRSP in dogs in Bangladesh.

Methods

A total of 358 swab samples were collected from different body sites of 150 dogs attending a university teaching veterinary hospital between January and June 2018. Standard bacteriological procedures were followed to isolate Staphylococcus, and identification was confirmed to the species level by PCR to detect the nuc gene. MRSA and MRSP were confirmed by the presence of the mecA gene.

Results

The prevalence of coagulase‐positive S. aureus and S. pseudintermedius in dogs were 16% and 45.3%, respectively. S. aureus and S. pseudintermedius isolates displayed the highest resistance against nalidixic acid (95.2% and 91%, respectively) and erythromycin (89.3% and 84.7%, respectively). Notably, all the staphylococcal isolates showed resistance to ≥3 antimicrobial classes. The prevalence of MRSA and MRSP in dogs was 8.7% and 6%, respectively. Multivariable logistic regression analysis identified the following variables as risk factors for MRSA colonisation in dogs: dogs with dermatitis (odds ratio [OR], 12.24, 95% CI: 3.12–57.33; p < 0.001) and history of antibiotic use (OR 8.73, 95% CI: 2.23–43.10; p < 0.001). Presence of otitis (OR 14.22; 95% CI: 1.64–103.58; p = 0.008) and oral lesions (OR 9.48, 95% CI: 1.14–64.82; p = 0.002) were identified as the significant risk factors for the carriage of MRSP.

Conclusions

The circulation of multidrug‐resistant S. aureus and S. pseudintermedius is a serious concern to dogs and humans. To our knowledge, this is the first report of S. pseudintermedius and MRSP affecting dogs in Bangladesh.

Patterns of antimicrobial drug use in veterinary primary care and specialty practice: A 6-year multi-institution study

BACKGROUND

Combatting antimicrobial resistance requires a One Health approach to antimicrobial stewardship including antimicrobial drug (AMD) use evaluation. Current veterinary AMD prescribing data are limited.

OBJECTIVES

To quantify companion animal AMD prescribing in primary care and specialty practice across 3 academic veterinary hospitals with particular focus on third-generation cephalosporins, fluoroquinolones, and carbapenems.

ANIMALS

Dogs and cats presented to 3 academic veterinary hospitals from 2012 to 2017.

METHODS

In this retrospective study, AMD prescribing data from 2012 to 2017 were extracted from electronic medical records at each hospital and prescriptions classified by service type: primary care, specialty practice or Emergency/Critical Care (ECC). Hospital-level AMD prescribing data were summarized by species, service type, AMD class, and drug. Multivariable logistic full-factorial regression models were used to estimate hospital, year, species, and service-type effects on AMD prescribing. Estimated marginal means and confidence intervals were plotted over time.

RESULTS

The probability of systemic AMD prescribing for any indication ranged between 0.15 and 0.28 and was higher for dogs than cats (P < .05) apart from 2017 at hospital 1. Animals presented to primary care were least likely to receive AMDs (dogs 0.03-0.15, cats 0.03-0.18). The most commonly prescribed AMD classes were aminopenicillins/β-lactamase inhibitors (0.02-0.15), first-generation cephalosporins (0.00-0.09), fluoroquinolones (0.00-0.04), nitroimidazoles (0.01-0.06), and tetracyclines (0.00-0.03). Among the highest priority classes, fluoroquinolones (dogs 0.00-0.09, cats 0.00-0.08) and third-generation cephalosporins (dogs 0.00-0.04, cats 0.00-0.05) were most frequently prescribed.

CONCLUSIONS AND CLINICAL IMPORTANCE

Antimicrobial drug prescribing frequencies were comparable to previous studies. Additional stewardship efforts might focus on fluoroquinolones and third-generation cephalosporins.

Antimicrobial Prescribing Practices in Dogs and Cats by Colombian Veterinarians in the City of Medellin

This study surveyed the prescribing behavior of Colombian companion animal veterinarians and compared the responses to the current guidelines of the International Society for Companion Animals on Infectious Diseases (ISCAID). A convenience sample of 100 primary-care veterinary practitioners was selected from the city of Medellin. A questionnaire was designed to present hypothetical clinical scenarios regarding prescription choices for systemic antimicrobials. The numbers of veterinarians empirically prescribing a course of systemic antimicrobials for each scenario were-perioperative elective surgeries (86%), superficial pyoderma (90%), lower urinary tract disease (52%), acute hemorrhagic diarrhea (50%), and kennel cough (46%). For urinary tract disease, cultures and susceptibility testing were only performed by half of the respondents, suggesting lower diagnostic standards. In superficial pyoderma cases, cytology was performed in the following percent of cases-0% (24), 20% (30), 40% (17), 60% (11), 80% (8), and 100% (10). Antimicrobials were over-prescribed relative to emerging standard for elective surgeries (86%), kennel cough (46%), and acute hemorrhagic diarrhea (50%). Critically important antimicrobials, such as fluoroquinolones, were applied commonly for superficial pyoderma (18%), kennel cough (12%), and lower urinary tract disease in dogs (20%) and cats (26%). In conclusion, antimicrobial prescribing behavior was inconsistent with current guidelines, and antimicrobial use could be improved by appropriate diagnostic steps allowing choice of an optimal antimicrobial drug. Overall, we documented the widespread use of antimicrobials for the treatment of these four common disease conditions.

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.

Antimicrobial agent use in small animals what are the prescribing practices, use of PK-PD principles, and extralabel use in the United States?

In this review, the availability and deficiencies of current antimicrobial agents for companion animals in the United States are described. Although several active agents are FDA-approved for small animals, there are many unmet needs. These needs are greatest for cats, for the treatment of antibiotic drug-resistant infections, and to treat new or emerging pathogens that were not considered on older labels. The older agents approved before 1997 are often outdated, unavailable, or have inaccurate labeling. Subsequently, veterinarians treat dogs and cats with many unapproved antimicrobial agents that are licensed for human use. Although these drugs may be effective, there are also concerns that this use can produce drug-resistant bacteria that may be a public health risk. Although this concern is real, there is also evidence that any antimicrobial use in small animals can produce resistant fecal bacteria and stewardship principles should aim at reducing any unnecessary antibiotic use. This could be accomplished by avoiding some of the older, ineffective, or outdated agents described in this paper. There is a need for incentives to approve new agents that will be more appropriate for treating infections in companion animals without increasing the risk of drug-resistant bacteria that could potentially be transferred to humans and the environment and create a public health risk.

Molecular and phenotypic characterization of methicillin-resistant Staphylococcus pseudintermedius from ocular surfaces of dogs and cats suffering from ophthalmological diseases

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) have recently emerged as a major therapeutic challenge in small animal medicine because of their antimicrobial multidrug resistance and their role as nosocomial pathogens. This study focused on the prevalence, molecular characteristics and antimicrobial resistance pheno- and genotypes of MRSP isolated from conjunctival swabs of dogs and cats. Conjunctival swabs were collected from 72 dogs and 24 cats suffering from conjunctivitis/blepharitis, keratitis or uveitis and screened for the presence of MRSP. S. pseudintermedius was isolated from 38 (39.6 %) of all samples. Three (7.9 %) S. pseudintermedius isolates were confirmed as MRSP. They harboured the mecA gene and originated from dogs. One MRSP isolate was from a case of uveitis while the other two MRSP isolates originated from cases of conjunctivitis/blepharitis. All MRSP isolates were subjected to broth microdilution and whole genome sequencing (WGS). Resistance and virulence genes, multilocus sequence (MLS), spa, dru and SCCmec types were deduced from WGS data. Two of the three MRSP isolates, IMT360/16 and IMT515/16, shared the same MLS type (ST71), spa type (t02), dru type (dt9a), SCCmec type (II-III), and indistinguishable multidrug resistance pheno- and genotypes, including resistance to β-lactams (blaZ, mecA), erythromycin and clindamycin (erm(B)), streptomycin (aphA3), gentamicin (aacA-aphD), enrofloxacin (mutations in grlA and gyrA), tetracycline (tet(K)), and trimethoprim (dfrG)/sulfamethoxazole. The third isolate, IMT1670/16, differed in all those characteristics (MLST (ST1403), dru type (dt10h), SCCmec type (IVg), except the spa type (t02). In addition, isolate IMT1670/16 carried a different tetracycline resistance gene (tet(M)) and was susceptible to erythromycin and clindamycin.

Persistent infection with Staphylococcus pseudintermedius in an adult oncology patient with transmission from a family dog

Staphylococcus pseudintermedius is a well known commensal organism of dogs but also a canine opportunistic pathogen. Reports of this organism being recovered from specimens from humans might suggest an increase prevalence in human infections and/or improved diagnostic leading to more accurate identification. Here we report a case of persistent S. pseudintermedius infection in an adult female oncology patient including colonization of the tip of an indwelling catheter. Diligence by laboratories in correctly isolating and identifying this pathogen (including susceptibility testing) is essential for optimal patient care.

A pilot study on the comparative minimum inhibitory and mutant prevention concentration values for moxifloxacin and pradofloxacin against canine and human isolates of Staphylococcus pseudintermedius and S. schleiferi

BACKGROUND

Moxifloxacin is a fourth-generation fluoroquinolone (FQ) that is approved for use in people to treat a variety of infections. Some veterinary microbiology laboratories report moxifloxacin in culture and sensitivity profiles for Staphylococcus pseudintermedius and S. schleiferi albeit using Clinical & Laboratory Standards Institute (CLSI) breakpoints for S. aureus. Previous studies have shown that S. aureus breakpoints can mischaracterize S. pseudintermedius susceptibility to various drugs. Pradofloxacin is a third generation veterinary FQ with a similar mechanism of action and spectrum of activity to moxifloxacin; however, the dose format (25 mg/mL solution) available in the USA may limit its practical use in large dogs.

OBJECTIVE

To determine the minimum inhibitory concentration (MIC), mutant prevention concentration (MPC) and mutant selection window (MSW) of moxifloxacin and pradofloxacin for isolates of S. pseudintermedius and S. schleiferi.

METHODS AND MATERIALS

Pulsed-field gel electrophoresis was performed to establish that each bacterial isolate selected for testing represented an unique strain. The MIC, MPC and MSW for moxifloxacin and pradofloxacin were determined from 60 strains of S. pseudintermedius and seven strains of S. schleiferi.

RESULTS

The MIC and MPC ranges of moxifloxacin and pradofloxacin for meticillin-susceptible S. pseudintermedius were similar. However, MIC and MPC ranges were much wider and resistance to both drugs was more common for meticillin-resistant strains of S. pseudintermedius and S. schleiferi.

CONCLUSIONS AND CLINICAL IMPORTANCE

The narrow MSW of these drugs may reduce the risk of selecting for antibiotic-resistant subpopulations. Pharmacokinetic, pharmacodynamic and safety studies are needed.

Development of a sprayable hydrogel formulation for the skin application of therapeutic antibodies

A formulation of an antibody with antibacterial properties for topical use on Staphylococcal skin infections was developed and characterized. The best formulation was obtained with 1.5% (w/v) sodium carboxymethylcellulose containing 10 mg/ml immunoglobulin. Spraying forces and rheological behavior were measured in order to characterize the hydrogel formulation. The percentage of antibody aggregates in gel as well as the antibody release, folding and target binding properties of the released antibody were analyzed to proof an acceptable shelf life and no significant changes in the activity of the antibody over time. No microbial contamination was observed in the chosen non-airless application container. Functional testing of the topical skin formulation was performed with an ex vivo biopsy culture model of dog skin. Histological analysis indicated efficacy in protection from Staphylococcus mediated skin damage and antibody delivery restricted to the epidermal surface. The results demonstrate that this hydrogel is suitable for cutaneous antibody applications in the medical field.

Use of an amikacin-infused collagen sponge concurrent with implant removal for treatment of tibial plateau leveling osteotomy surgical site infection in 31 cases

OBJECTIVE

To report the use and long-term outcome of dogs with surgical site infection (SSI) after tibial plateau leveling osteotomy (TPO), treated with an amikacin-infused collagen sponge and implant removal.

STUDY DESIGN

Retrospective study.

ANIMALS

Thirty-one client-owned dogs.

METHODS

Medical records were reviewed for dogs with SSI after a TPLO that were treated with surgical implant removal and concurrent implantation of an amikacin-infused collagen sponge. Relevant clinical and surgical data were recorded. The TPLO implants were routinely removed; the surgical site was swabbed for culture. The sponge was aseptically infused with amikacin prior to implantation. Postprocedure examinations consisted of visual inspection of the incision by the surgeon and lameness scoring.

RESULTS

Thirty-one dogs met all inclusion criteria. Median follow-up time was 687 days. Short-term examination after implant removal and sponge implantation revealed uneventful incisional healing in 24 dogs. Six (19.4%) dogs exhibited inflamed incision sites a median of 4 days (range, 3-9) postoperatively that resolved without additional treatment. One (3.2%) dog required empirical antibiotic treatment 7 days postoperatively but was lost to long-term follow-up. Long-term follow-up examination revealed no clinical evidence of SSI recurrence and no lameness in the remaining 30 cases.

CONCLUSION

Surgical implant removal and implantation of an absorbable collagen sponge infused with amikacin alone was an effective treatment for postoperative TPLO SSI.

CLINICAL SIGNIFICANCE

This procedure had a 96.8% long-term resolution of SSI. It should be considered as a treatment option for TPLO SSI.

Molecular characterisation of methicillin-resistant Staphylococcus pseudintermedius from dogs and the description of their SCCmec elements

In recent years an increasing number of methicillin-resistant S. pseudintermedius (MRSP) has been observed in both, healthy and clinically infected dogs. The aim of the study was the characterisation of MRSP isolates from clinical routine diagnostics of a German laboratory in order to assess the abundancy of resistance genes and SCCmec elements. 97 isolates from 96 dogs were analysed using microarrays detecting resistance genes and SCCmec-associated markers. All isolates harboured mecA and blaZ. Other abundant resistance markers (in >80% of isolates) included aacA-aphD, aphA3 and sat as well as erm(B). Tetracycline resistance genes (tet(K), tet(M)) and cat also were common (in >20%). The vast majority (n = 59) of isolates carried SCCmec III elements. SCCmec IV and V elements were identified in 21 and 15 isolates, respectively. Irregular or pseudo-SCCmec elements were found in 2 isolates. The high degree of uniformity of hybridisation patterns of tested strains suggest that the majority of MRSP infections was caused by one single strain and comparison to previously published reports and sequences suggest that this was the ST71-SCCmec III strain that also predominates elsewhere in Western Europe.

The Dynamic Nature of Canine and Feline Infectious Disease Risks in the Twenty-first Century

Canine and feline infectious diseases are constantly changing in frequency and location. Numerous drivers or determinants of these changes are suspected, including emergence of new pathogens; change in virulence and resistance of existing pathogens; change in land use, climate, and weather; travel and trade; habitat destruction and urbanization; change in animal-animal contact networks; host susceptibility; availability and uptake of prevention measures; and change in ability to detect pathogens and track diseases. This article explores each of these proposed drivers and examines examples of feline and canine diseases likely to be influenced by them.

Treatment of Selected Canine Dermatological Conditions in Portugal - A Research Survey

INTRODUCTION

Staphylococcus pseudintermedius and Malassezia pachydermatis often cause skin diseases in dogs.

MATERIAL AND METHODS

An online survey was e-mailed to veterinary practices nationwide covering demographics, diagnosis methods, and oral and topical treatment options. Of the 740 surveys sent, 100 complete replies were obtained.

RESULTS

The majority of clinicians were unaware of the existence of the International Society for Companion Animal Infectious Diseases guidelines or did not follow them (53%). Oral antibiotics were used universally for superficial bacterial folliculitis treatment, particularly amoxicillin-clavulanic acid (100%), cephalexin (94%), enrofloxacin (67%), or marbofloxacin (60%). For fold dermatitis (FD) and otitis externa (OE), oral antibiotics were also given as treatment in 88% and 82% of cases, respectively. Oral antifungals were often prescribed for generalised Malassezia dermatitis (85%), FD (70%), and OE (59%). S. pseudintermedius and M. pachydermatis were frequently treated topically, particularly with antibacterials or antifungals only, or a combination of antibacterials, antifungals, and glucocorticoids. Alternative options such as honey-based products were not frequently used.

CONCLUSION

Our survey suggests that oral antibiotics are overused by Portuguese clinicians despite the spread of antibiotic resistant S. pseudintermedius. Oral antibiotics and antifungals are commonly prescribed for skin conditions manageable with topical treatments.

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

PURPOSE

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

METHODOLOGY

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

CONCLUSION

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

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.

Bilateral bullous keratopathy secondary to melting keratitis in a Suri alpaca (Vicugna pacos)

An young alpaca was evaluated for bilateral progressive melting corneal ulcers and developped secondary bullous keratopathy during hospitalization. The tragic progression of melting ulcers in both eyes observed in our case leads us to recommend a rapid intensive medical therapy in young and debilitated alpacas presenting a corneal ulcer.

Effect of prophylactic cefalexin treatment on the development of bacterial infection in acute radiation-induced dermatitis in dogs: a blinded randomized controlled prospective clinical trial

BACKGROUND

Acute radiation-induced dermatitis (ARID) is a common sequela of radiation therapy and carries the risk of secondary bacterial skin infection. No standard of care exists for managing canine ARID and evidence-based guidelines are lacking; however, prophylactic use of antibiotics is common.

HYPOTHESIS/OBJECTIVES

To evaluate the impact of prophylactic cefalexin on the prevalence and severity of bacterial infection in canine ARID.

ANIMALS

Seventeen dogs treated with definitive-intent radiotherapy.

METHODS

All dogs were treated with definitive-intent radiation therapy (48-57.5 gray) targeted to the skin surface. Dogs were randomized to receive either prophylactic cefalexin (22 mg/kg twice daily) beginning halfway through the prescribed radiotherapy course (cohort A) or to serve as controls (cohort B). Aerobic skin cultures and surface cytological evaluation were performed at first onset of moist desquamation and one week following completion of radiation therapy. Skin toxicity grading and owner quality of life (QoL) questionnaires were performed weekly. The rate of infection, multidrug resistance status, toxicity severity and QoL between cohorts were compared.

RESULTS

Staphylococcus schleiferi and S. pseudintermedius were the most frequent bacterial agents isolated in both cohorts. There was no significant difference in prevalence of bacterial infection or overall QoL between cohorts at either time point; however, multidrug-resistant infections were significantly increased in cohort A versus cohort B. Clinician- and client-perceived severity of toxicity was significantly greater and median duration of moist desquamation was significantly longer in cohort A than cohort B.

CONCLUSIONS AND CLINICAL IMPORTANCE

Prophylactic use of cefalexin for management of canine ARID is not recommended.

Systematic Review on Global Epidemiology of Methicillin-Resistant Staphylococcus pseudintermedius: Inference of Population Structure from Multilocus Sequence Typing Data

Background and rationale: Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is a major cause of infections in dogs, also posing a zoonotic risk to humans. This systematic review aimed to determine the global epidemiology of MRSP and provide new insights into the population structure of this important veterinary pathogen.

Methodology: Web of Science was searched systematically for articles reporting data on multilocus sequence typing (MLST) of S. pseudintermedius isolates from dogs or other animal or human patients and carriers. Data from the eligible studies were then integrated with data from the MLST database for this species. Analysis of MLST data was performed with eBURST and ClonalFrame, and the proportion of MRSP isolates resistant to selected antimicrobial drugs was determined for the most predominant clonal complexes.

Results: Fifty-eight studies published over the last 10 years were included in the review. MRSP represented 76% of the 1428 isolates characterized by the current MLST scheme. The population of S. pseudintermedius was highly diverse and included five major MRSP clonal complexes (CCs). CC71, previously described as the epidemic European clone, is now widespread worldwide. In Europe, CC258, which is more frequently susceptible to enrofloxacin and aminoglycosides, and more frequently resistant to sulphonamides/trimethoprim than CC71, is increasingly reported in various countries. CC68, previously described as the epidemic North American clone, is frequently reported in this region but also in Europe, while CC45 (associated with chloramphenicol resistance) and CC112 are prevalent in Asia. It was estimated that clonal diversification in this species is primarily driven by homologous recombination (r/m = 7.52).

Conclusion: This study provides evidence that S. pseudintermedius has an epidemic population structure, in which five successful MRSP lineages with specific traits regarding antimicrobial resistance, genetic diversity and geographical distribution have emerged upon a weakly clonal background through acquisition of SCCmec and other mobile genetic elements.

Comparison of the In vitro Activity of Five Antimicrobial Drugs against Staphylococcus pseudintermedius and Staphylococcus aureus Biofilms

Resistance in canine pathogenic staphylococci is necessitating re-evaluation of the current antimicrobial treatments especially for biofilm-associated infections. Long, repeated treatments are often required to control such infections due to the tolerance of bacteria within the biofilm. To comply with the goal of better antibiotic stewardship in veterinary medicine, the efficacies of the available drugs need to be directly assessed on bacterial biofilms. We compared the activities of amoxicillin, cefalexin, clindamycin, doxycycline, and marbofloxacin on in vitro biofilms of Staphylococcus pseudintermedius and Staphylococcus aureus. Exposure of biofilms for 15 h to maximum concentrations of the antibiotics achievable in canine plasma only reduced biofilm bacteria by 0.5–2.0 log₁₀ CFU, compared to the control, except for marbofloxacin which reduced S. aureus biofilms by 5.4 log₁₀ CFU. Two-antibiotic combinations did not improve, and even decreased, bacterial killing. In comparison, 5 min-exposure to 2% chlorhexidine reduced biofilms of the two tested strains by 4 log₁₀ CFU. Our results showed that S. pseudintermedius and S. aureus biofilms were highly tolerant to all the drugs tested, consistent with the treatment failures observed in practice. Under our in vitro conditions, the use of chlorhexidine was more efficacious than antimicrobials to reduce S. pseudintermedius biofilm.

Colonization with methicillin-resistant Staphylococcus pseudintermedius in multi-dog households: A longitudinal study using whole genome sequencing

Despite a worldwide increase in the presence of methicillin-resistant Staphylococcus pseudintermedius (MRSP) in dogs and its potential to cause serious canine health problem, the understanding of the transmission and long-term carriage of MRSP is limited. The objective of this study was to investigate the transmission of MRSP to contact dogs living in multiple dog households where one or more of the dogs had been diagnosed with a clinically apparent infection with MRSP. MRSP carriage was investigated over several months in 11 dogs living in four separate multiple dog households where an MRSP infection in a dog had been diagnosed. Whole-genome sequencing was used for genotypic characterization. Contact dogs were only MRSP-positive if the index dog was positive on the same sample occasion. Three contact dogs were consistently MRSP-negative. The data from whole genome sequencing showed similarities between isolates within each family group, indicating that MRSP was transmitted within each family. The results show that the risk of MRSP-colonization in dogs living with an MRSP-infected dog is reduced if the index dog becomes MRSP negative. All of the contact dogs will not carry MRSP continuously during the time the index dog is MRSP-positive. The information yielded from whole genome sequencing showed the methodology to be a promising additional tool in epidemiologic investigations of MRSP transmission.

Prior antibacterial drug exposure in dogs with meticillin-resistant Staphylococcus pseudintermedius (MRSP) pyoderma

BACKGROUND

The emergence of meticillin-resistant Staphylococcus pseudintermedius (MRSP) has become a significant animal health problem. Recent studies have indicated that previous antibacterial drug exposure is a factor in acquisition of meticillin-resistant strains of staphylococci.

HYPOTHESIS/OBJECTIVES

The purpose of this study was to identify factors associated with prior antimicrobial drug use and MRSP pyoderma in dogs presented to a veterinary teaching hospital.

ANIMALS

Dogs diagnosed with pyoderma associated with MRSP (n = 53) or meticillin-sensitive S. pseudintermedius (MSSP; n = 45).

METHODS

The medical records of dogs diagnosed with pyoderma associated with isolation of S. pseudintermedius between January 2006 and November 2012 were reviewed. All cases with a complete twelve month to 3 yr drug history prior to the diagnosis were included.

RESULTS

Fifty two of 53 (98%) MRSP cases and 42 of 45 (93%) MSSP cases had received at least one course of antibacterial drug prior to diagnosis. The total number of antibacterial drug prescriptions provided to pet owners and the variety of antibacterial drug classes represented were higher for cases with MRSP than for cases with MSSP (P < 0.0001 and P = 0.009, respectively). More cases with MRSP (98%) received beta-lactam drugs than those with MSSP (82%; P = 0.007) and the proportion of MRSP cases that had received concurrent immunomodulatory therapy was higher (62% versus 42%; P = 0.048).

CONCLUSIONS AND CLINICAL IMPORTANCE

These results suggest that the total number of antibacterial drug prescriptions, exposure to multiple drug classes (beta-lactams in particular) and concurrent immunomodulatory therapy may be associated with increased risk for acquisition of MRSP.

Genotypic relatedness and characterization of Staphylococcus pseudintermedius associated with post-operative surgical infections in dogs

Staphylococcus pseudintermedius is a commensal organism of dogs that can also be implicated in surgical site infections (SSIs) in dogs. Particularly with the recent emergence and spread of the ST71-t02-SCCmecII-III multidrug-resistant S. pseudintermedius clonal lineage (MDRSP), it is important to understand the clonal diversity of S. pseudintermedius in SSIs in dogs. The study reported here investigated the genotypic relatedness of 124 S. pseudintermedius isolates from the surgical wounds of 90 dogs admitted to a referral practice in the UK. This study also aimed to understand whether MDRSP is better adapted to survival and persistence in different environments compared with other S. pseudintermedius. Whilst no individual S. pseudintermedius clonal type was primarily responsible for S. pseudintermedius-associated SSIs in dogs, we found that MDRSP was the most represented clonal type among the isolates studied. However, we observed no difference in the level of biofilm production, susceptibility to biocides or carriage of specific virulence determinants between MDRSP and other S. pseudintermedius isolates studied. Interestingly, in the competitive fitness study, MDRSP did not outcompete any member of the other S. pseudintermedius isolates studied in each environment. Our data suggest that the determinants that promote S. pseudintermedius-associated SSIs in dogs are distributed among S. pseudintermedius as a species and are not restricted to a few clonal types. They also provide evidence to support the suggestion that MDRSP is not better adapted to survival or persistence in different environments and is no more virulent than other S. pseudintermedius isolates.

Evaluation of Oxacillin and Cefoxitin Disk and MIC Breakpoints for Prediction of Methicillin Resistance in Human and Veterinary Isolates of Staphylococcus intermedius Group

Staphylococcus pseudintermedius is a coagulase-positive species that colonizes the nares and anal mucosa of healthy dogs and cats. Human infections with S. pseudintermedius range in severity from bite wounds and rhinosinusitis to endocarditis; historically, these infections were thought to be uncommon, but new laboratory methods suggest that their true incidence is underreported. Oxacillin and cefoxitin disk and MIC tests were evaluated for the detection of mecA- or mecC-mediated methicillin resistance in 115 human and animal isolates of the Staphylococcus intermedius group (SIG), including 111 Staphylococcus pseudintermediusand 4 Staphylococcus delphini isolates, 37 of which were mecA positive. The disk and MIC breakpoints evaluated included the Clinical and Laboratory Standards Institute (CLSI) M100-S25 Staphylococcus aureus/Staphylococcus lugdunensis oxacillin MIC breakpoints and cefoxitin disk and MIC breakpoints, the CLSI M100-S25 coagulase-negative Staphylococcus (CoNS) oxacillin MIC breakpoint and cefoxitin disk breakpoint, the CLSI VET01-S2 S. pseudintermedius oxacillin MIC and disk breakpoints, and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) S. pseudintermedius cefoxitin disk breakpoint. The oxacillin results interpreted by the VET01-S2 (disk and MIC) and M100-S25 CoNS (MIC) breakpoints agreed with the results of mecA/mecC PCR for all isolates, with the exception of one false-resistant result (1.3% of mecA/mecC PCR-negative isolates). In contrast, cefoxitin tests performed poorly, ranging from 3 to 89% false susceptibility (very major errors) and 0 to 48% false resistance (major errors). BD Phoenix, bioMérieux Vitek 2, and Beckman Coulter MicroScan commercial automated susceptibility test panel oxacillin MIC results were also evaluated and demonstrated >95% categorical agreement with mecA/mecC PCR results if interpreted by using the M100-S25 CoNS breakpoint. The Alere penicillin-binding protein 2a test accurately detected all mecA-positive isolates, although for four isolates, cefoxitin induction was required prior to testing. These data demonstrate that the cefoxitin surrogate test does not reliably detect the presence of mecA in S. pseudintermedius isolates and that laboratories should perform oxacillin disk or MIC tests of these isolates when they are encountered.

Isolation of coagulase-positive staphylococci from bitches' colostrum and milk and genetic typing of methicillin-resistant Staphylococcus pseudintermedius strains

Background

Among the coagulase-positive, potentially pathogenic staphylococci, Staphylococcus pseudintermedius has been frequently isolated from bitches’ milk. This organism colonizes the mammary gland or causes infection, while S. aureus has been only occasionally reported. The objective of this study was to investigate the occurrence and persistence of coagulase-positive staphylococci in the colostrum and milk of postpartum bitches, either treated or untreated with antimicrobials, and to assess the incidence, antibiotic resistance profile and genetic type of the methicillin-resistant strains.

On postpartum D1, D7 and D15, drops of secretion were collected from the mammary glands of 27 postpartum bitches, nine of which were treated with antimicrobials. Coagulase-positive staphylococci were identified, antimicrobial susceptibility and the presence of mecA were tested and the genetic profile of methicillin-resistant strains was assessed.

Results

Staphylococcus pseudintermedius was the only coagulase-positive staphylococcus isolated, and its presence was detected in 21 out of 27 bitches and in 66 out of 145 swabs. In a single bitch, it caused puerperal mastitis. In untreated bitches, the frequency of isolation was lower in colostrum than in milk. All of the isolates except one were resistant to at least three antimicrobial classes, while 14 out of 66 S. pseudintermedius strains were methicillin-resistant mecA positive (MRSP) and were isolated from eight bitches housed in the same breeding kennel. A significant association was found between antimicrobial treatment and the presence of MRSP. Six of the 12 typed isolates belonged to spa-type t02 carrying SCCmec II/III, and another six were non-typeable with spa carrying SCCmec IV. The t02-SCCmec II/III isolates were sequence type (ST) 71; four NT-SCCmec IV isolates were ST258 and two were ST369. PFGE showed that isolates from the same dog had identical band patterns, while isolates from different dogs had unique band patterns. MRSP strains showed multidrug resistance profiles.

Conclusions

Our results confirm that S. pseudintermedius is the most frequently isolated coagulase-positive staphylococcus from bitches’ milk. The isolation of several different strains of MRSP with different genetic characteristics in the same kennel and the fact that two of the strains belonged to a sequence type (ST) described for the first time are noteworthy findings.

Antibacterial Characterization of Novel Synthetic Thiazole Compounds against Methicillin-Resistant Staphylococcus pseudintermedius

Staphylococcus pseudintermedius is a commensal organism of companion animals that is a significant source of opportunistic infections in dogs. With the emergence of clinical isolates of S. pseudintermedius (chiefly methicillin-resistant S. pseudintermedius (MRSP)) exhibiting increased resistance to nearly all antibiotic classes, new antimicrobials and therapeutic strategies are urgently needed. Thiazole compounds have been previously shown to possess potent antibacterial activity against multidrug-resistant strains of Staphylococcus aureus of human and animal concern. Given the genetic similarity between S. aureus and S. pseudintermedius, this study explores the potential use of thiazole compounds as novel antibacterial agents against methicillin-sensitive S. pseudintermedius (MSSP) and MRSP. A broth microdilution assay confirmed these compounds exhibit potent bactericidal activity (at sub-microgram/mL concentrations) against both MSSA and MRSP clinical isolates while the MTS assay confirmed three compounds (at 10 μg/mL) were not toxic to mammalian cells. A time-kill assay revealed two derivatives rapidly kill MRSP within two hours. However, this rapid bactericidal activity was not due to disruption of the bacterial cell membrane indicating an alternative mechanism of action for these compounds against MRSP. A multi-step resistance selection analysis revealed compounds 4 and 5 exhibited a modest (two-fold) shift in activity over ten passages. Furthermore, all six compounds (at a subinihibitory concentration) demonstrated the ability to re-sensitize MRSP to oxacillin, indicating these compounds have potential use for extending the therapeutic utility of β-lactam antibiotics against MRSP. Metabolic stability analysis with dog liver microsomes revealed compound 3 exhibited an improved physicochemical profile compared to the lead compound. In addition to this, all six thiazole compounds possessed a long post-antibiotic effect (at least 8 hours) against MRSP. Collectively the present study demonstrates these synthetic thiazole compounds possess potent antibacterial activity against both MSSP and MRSP and warrant further investigation into their use as novel antimicrobial agents.

ACVIM consensus statement on therapeutic antimicrobial use in animals and antimicrobial resistance

The epidemic of antimicrobial resistant infections continues to challenge, compromising animal care, complicating food animal production and posing zoonotic disease risks. While the overall role of therapeutic antimicrobial use in animals in the development AMR in animal and human pathogens is poorly defined, veterinarians must consider the impacts of antimicrobial use in animal and take steps to optimize antimicrobial use, so as to maximize the health benefits to animals while minimizing the likelihood of antimicrobial resistance and other adverse effects. This consensus statement aims to provide guidance on the therapeutic use of antimicrobials in animals, balancing the need for effective therapy with minimizing development of antimicrobial resistance in bacteria from animals and humans.

Seven common mistakes to avoid in achieving long-term success with dermatology patients

Managing a pet's chronic dermatologic conditions can be frustrating for both clients and clinicians, but there are steps to making the process easier for everyone. Avoid the following seven mistakes sometimes made in managing dermatology cases and you will find the process considerably easier in the future.

Fighting surgical site infections in small animals: are we getting anywhere?

A diverse array of pathogen-related, patient-related, and caretaker-related issues influence risk and prevention of surgical site infections (SSIs). The entire surgical team involved in health care settings in which surgical procedures are performed play a pivotal role in the prevention of SSIs. In this article, current knowledge of SSI risk factors and prevention methods is reviewed. Although new avenues that can be explored in the prevention of SSIs in veterinary medicine are described, the main conclusion drawn is that the best method for prevention of SSI is to adhere to what we already know.

Large outbreak caused by methicillin resistant Staphylococcus pseudintermedius ST71 in a Finnish Veterinary Teaching Hospital--from outbreak control to outbreak prevention

Introduction

The purpose of this study was to describe a nosocomial outbreak caused by methicillin resistant Staphylococcus pseudintermedius (MRSP) ST71 SCCmec II-III in dogs and cats at the Veterinary Teaching Hospital of the University of Helsinki in November 2010 – January 2012, and to determine the risk factors for acquiring MRSP. In addition, measures to control the outbreak and current policy for MRSP prevention are presented.

Methods

Data of patients were collected from the hospital patient record software. MRSP surveillance data were acquired from the laboratory information system. Risk factors for MRSP acquisition were analyzed from 55 cases and 213 controls using multivariable logistic regression in a case-control study design. Forty-seven MRSP isolates were analyzed by pulsed field gel electrophoresis and three were further analyzed with multi-locus sequence and SCCmec typing.

Results

Sixty-three MRSP cases were identified, including 27 infections. MRSPs from the cases shared a specific multi-drug resistant antibiogram and PFGE-pattern indicated clonal spread. Four risk factors were identified; skin lesion (OR = 6.2; CI_95% 2.3–17.0, P = 0.0003), antimicrobial treatment (OR = 3.8, CI_95% 1.0–13.9, P = 0.0442), cumulative number of days in the intensive care unit (OR = 1.3, CI_95% 1.1–1.6, P = 0.0007) or in the surgery ward (OR = 1.1, CI_95% 1.0–1.3, P = 0.0401). Tracing and screening of contact patients, enhanced hand hygiene, cohorting and barrier nursing, as well as cleaning and disinfection were used to control the outbreak. To avoid future outbreaks and spread of MRSP a search-and-isolate policy was implemented. Currently nearly all new MRSP findings are detected in screening targeted to risk patients on admission.

Conclusion

Multidrug resistant MRSP is capable of causing a large outbreak difficult to control. Skin lesions, antimicrobial treatment and prolonged hospital stay increase the probability of acquiring MRSP. Rigorous control measures were needed to control the outbreak. We recommend the implementation of a search-and-isolate policy to reduce the burden of MRSP.

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.

Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis (Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases)

BACKGROUND

Superficial bacterial folliculitis (SBF) is usually caused by Staphylococcus pseudintermedius and routinely treated with systemic antimicrobial agents. Infection is a consequence of reduced immunity associated with alterations of the skin barrier and underlying diseases that may be difficult to diagnose and resolve; thus, SBF is frequently recurrent and repeated treatment is necessary. The emergence of multiresistant bacteria, particularly meticillin-resistant S. pseudintermedius (MRSP), has focused attention on the need for optimal management of SBF.

OBJECTIVES

Provision of an internationally available resource guiding practitioners in the diagnosis, treatment and prevention of SBF.

DEVELOPMENT OF THE GUIDELINES

The guidelines were developed by the Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases, with consultation and advice from diplomates of the American and European Colleges of Veterinary Dermatology. They describe optimal methods for the diagnosis and management of SBF, including isolation of the causative organism, antimicrobial susceptibility testing, selection of antimicrobial drugs, therapeutic protocols and advice on infection control. Guidance is given for topical and systemic modalities, including approaches suitable for MRSP. Systemic drugs are classified in three tiers. Tier one drugs are used when diagnosis is clear cut and risk factors for antimicrobial drug resistance are not present. Otherwise, tier two drugs are used and antimicrobial susceptibility tests are mandatory. Tier three includes drugs reserved for highly resistant infections; their use is strongly discouraged and, when necessary, they should be used in consultation with specialists.

CONCLUSIONS AND CLINICAL IMPORTANCE

Optimal management of SBF will improve antimicrobial use and reduce selection of MRSP and other multidrug-resistant bacteria affecting animal and human health.

Case-control risk factor study of methicillin-resistant Staphylococcus pseudintermedius (MRSP) infection in dogs and cats in Germany

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) has emerged as a highly drug-resistant small animal veterinary pathogen. Although often isolated from outpatients in veterinary clinics, there is concern that MRSP follows a veterinary-hospital-associated epidemiology. This study's objective was to identify risk factors for MRSP infections in dogs and cats in Germany. Clinical isolates of MRSP cases (n=150) and methicillin-susceptible S. pseudintermedius (MSSP) controls (n=133) and their corresponding host signalment and medical data covering the six months prior to staphylococcal isolation were analysed by multivariable logistic regression. The identity of all MRSP isolates was confirmed through demonstration of S. intermedius-group specific nuc and mecA. In the final model, cats (compared to dogs, OR 18.5, 95% CI 1.8-188.0, P=0.01), animals that had been hospitalised (OR 104.4, 95% CI 21.3-511.6, P<0.001), or visited veterinary clinics more frequently (>10 visits OR 7.3, 95% CI 1.0-52.6, P=0.049) and those that had received topical ear medication (OR 5.1, 95% CI 1.8-14.9, P=0.003) or glucocorticoids (OR 22.5, 95% CI 7.0-72.6, P<0.001) were at higher risk of MRSP infection, whereas S. pseudintermedius isolates from ears were more likely to belong to the MSSP-group (OR 0.09, 95% CI 0.03-0.34, P<0.001). These results indicate an association of MRSP infection with veterinary clinic/hospital settings and possibly with chronic skin disease. There was an unexpected lack of association between MRSP and antimicrobial therapy; this requires further investigation but may indicate that MRSP is well adapted to canine skin with little need for selective pressure.

Methicillin-resistant staphylococcal contamination of clothing worn by personnel in a veterinary teaching hospital

OBJECTIVE

To determine the methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP) contamination rate of white coats (WC) and surgical scrubs (SS) worn by personnel at the Ontario Veterinary College Health Sciences Centre (OVCHSC) and to identify risk factors associated with clothing contamination.

STUDY DESIGN

Cross-sectional study.

SAMPLE POPULATION

Personnel including clinical faculty, house officers, technicians, and veterinary students working at the OVCHSC.

METHODS

Electrostatic cloths were used to sample WC and SS of hospital personnel. Samples were tested for MRSA and MRSP and isolates were typed. Participants completed a self-administered questionnaire and data was evaluated for risk factors.

RESULTS

Of 114 specimens, MRS were isolated from 20 (17.5%), MRSA from 4 (3.5%), and MRSP from 16 (14.0%). Technicians were 9.5× (OR = 0.95, 95% CI: 1.2-∞, P = .03) more likely than students to have clothing contaminated with MRSA. No risk factors were identified for MRSP or for overall MRS contamination.

CONCLUSIONS

Standard hospital clothing was found to have a high prevalence of MRS contamination in a veterinary teaching hospital and could be a source of hospital-acquired infections.

Public health impact and antimicrobial selection of meticillin-resistant staphylococci in animals

Whilst meticillin-resistant Staphylococcus aureus (MRSA) infections reported sporadically in companion animals and cattle in the 1970s were probably of human origin, the recently emerged livestock-associated MRSA (LA-MRSA) and meticillin-resistant Staphylococcus pseudintermedius (MRSP) strains clearly have animal origins and their isolation from humans is usually associated with exposure to livestock and companion animals, respectively. LA-MRSA is primarily an occupational health risk to farm workers and veterinarians. The risk that this zoonotic agent may spread in the community is particularly acute in countries with high livestock production and low MRSA prevalence in the human population. MRSP is primarily a threat to animal health, and cases of human infection are rare but may be overlooked in diagnostic laboratories. There is no conclusive evidence of antimicrobial selection associated with the sudden emergence of LA-MRSA and MRSP. However, the rapid global spread of these bacteria has presumably been favoured by antimicrobial selective pressure. Tetracyclines, zinc and extended-spectrum cephalosporins (including extra-label use) are the most likely selective drivers implicated in the spread of LA-MRSA, whilst increased use of broad-spectrum β-lactams and fluoroquinolones, partly enhanced by extra-label use and the introduction of cheap generics, may have played an important role in the rapid dissemination of MRSP. Control of LA-MRSA and MRSP requires a dual approach aimed at reducing antimicrobial consumption and preventing transmission between animals and from animals to humans or vice versa. Restricted use of fluoroquinolones and cephalosporins in livestock, and national practice guidelines for rational antimicrobial use both in food and companion animals are warranted.