Increasing antimicrobial resistance in clinical isolates of Staphylococcus intermedius group bacteria and emergence of MRSP in the UK

Intervention with impact: Reduced isolation of methicillin-resistant Staphylococcus pseudintermedius from dogs following the introduction of antimicrobial prescribing legislation in Germany

BACKGROUND

Legislation was introduced in Germany in 2018, requiring bacterial culture and antimicrobial susceptibility testing before the prescription of fluoroquinolones and third-generation cephalosporins to dogs. We hypothesised that, following this intervention, the number of clinical samples testing positive for methicillin-resistant Staphylococcus pseudintermedius (MRSP) would reduce.

METHODS

Reports of S. pseudintermedius isolated from canine clinical samples by three German veterinary diagnostic microbiology laboratories during the 38 months before the introduction of the legislation and the 46 months after were compared. Bacterial identification was performed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, and antimicrobial susceptibility testing followed recognised recommendations but with changes during the study period.

RESULTS

Among a total of 120,571 S. pseudintermedius isolates, MRSP accounted for 7.1% overall. Following the legislative intervention, monthly submissions yielding S. pseudintermedius increased at all three laboratories. The MRSP percentage was lower in the period after the intervention in two of the three laboratories (p < 0.001); in the third laboratory, there was no change between periods, but a year-on-year reduction in MRSP percentages occurred after the intervention (p = 0.0004).

LIMITATIONS

Changing susceptibility testing methods limited the direct comparison of resistance patterns among laboratories.

CONCLUSION

The reduction in MRSP in canine clinical samples following the introduction of this legislation suggests a positive impact of compulsory laboratory testing on reducing antimicrobial resistance.

Occurrence of Antimicrobial Resistance in Canine and Feline Bacterial Pathogens in Germany under the Impact of the TÄHAV Amendment in 2018

The occurrence of antimicrobial resistance due to the use of antimicrobials is considered to be a main cause for treatment failure of bacterial infections in humans and animals. The right of German veterinarians to use and prescribe medications such as antimicrobials is regulated by the Regulation of Veterinary Pharmacies (TÄHAV). The aim of this study was to investigate the impact of the second amendment to the TÄHAV in 2018 on the occurrence of antimicrobial resistance in selected bacterial pathogens isolated from dogs and cats in Germany. For this purpose, we analyzed antimicrobial susceptibility data from 38 German small animal practices gathered between 2015 and 2021 in cooperation with Laboklin (Labor für klinische Diagnostik GmbH & Co.KG, Bad Kissingen, Germany). Annual cumulative susceptibility data of eight bacterial species were analyzed and compared. The mean value of resistant isolates was determined for each year and supplemented by 95% confidence intervals. Encouraged by the amendment, an increase in sample submissions was observed in Germany. The highest resistance rates to the analyzed substances penicillin G, ampicillin, amoxicillin-clavulanic acid, cefovecin, and enrofloxacin were found for Staphylococcus pseudintermedius (S. pseudintermedius), S. aureus, and Escherichia coli (E. coli). In contrast, resistance rates were low for Pasteurella multocida (P. multocida) and β-hemolytic streptococci. Significant resistance trends (p < 0.05) assumed as influenced by the TÄHAV amendment could be the significant decreases in resistance rates of S. pseudintermedius against penicillin G to 67% (n = 322/479), and ampicillin to 63% (n = 286/453), as well as S. felis against amoxicillin-clavulanic acid and cefovecin to 2% (n = 2/109), furthermore, the reduction in the occurrence of resistance of S. aureus against enrofloxacin to 4% (n = 3/76) in 2021. Moreover, for all species, the efficacy against the analyzed substances was maintained over the study period.

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.

High prevalence of antimicrobial resistance and multidrug resistance among bacterial isolates from diseased pets: Retrospective laboratory data (2015-2017)

Laboratory surveillance and the monitoring of antimicrobial resistance (AMR) trends and patterns among local isolates have been highly effective in providing comprehensive information for public health decision-making. A total of 396 cases along with 449 specimens were received for antibiotic susceptibility testing at a public university veterinary diagnostic laboratory in Malaysia between 2015 and 2017. Escherichia coli was the most frequently isolated (n = 101, 13%) bacteria, followed by Staphylococcus pseudintermedius (n = 97, 12%) and Streptococcus canis (n = 62, 8%). In cats, S. pseudintermedius isolates were highly resistant to azithromycin (90%), while the E. coli isolates were highly resistant to doxycycline (90%), tetracycline (81%), and cephalexin (75%). About 55% of S. pseudintermedius and 82% of E. coli were multi-drug resistant (MDR). In dogs, S. intermedius isolates were highly resistant to aminoglycosides neomycin (90.9%) and gentamicin (84.6%), and tetracycline (75%). Whereas the E. coli isolates were highly resistant to cephalexin (82.1%) and amoxicillin/clavulanic acid (76.5%). MDR was observed in 60% of S. intermedius and 72% of E. coli from dogs. Generally, the bacterial isolates from cats demonstrated higher levels of resistance to multiple antibiotics compared to those from dogs.

A Cross-Sectional Study of Veterinarians in Germany on the Impact of the TÄHAV Amendment 2018 on Antimicrobial Use and Development of Antimicrobial Resistance in Dogs and Cats

To minimize the use of third- and fourth-generation cephalosporins and fluoroquinolones, the 2018 amendment to the regulations of veterinary pharmacies (TÄHAV) introduced legal restrictions in Germany. In an online survey among German veterinarians, we investigated the influence of these requirements on the use of antibiotics in the treatment of dogs and cats and the development of resistance rates. It was found that, on average, between 21% and 30% of daily treated dogs and cats received antimicrobial therapy. The TÄHAV amendment led to a less frequent use of highest priority critically important antimicrobials (HPCIA) in 79% (240/303) of respondents and less antimicrobial use in general in 36% (108/303). As a result of these legal changes, 63% (190/303) of participants requested antimicrobial susceptibility testing (AST) more frequently. Participants consulted ASTs particularly frequently for treatment of otitis externa with 63% (190/303), cystitis with 55% (168/303), wounds with 44% (132/303), and pyoderma with 29% (88/303). Veterinarians also noted an increased loss of antimicrobial efficacy, especially when treating these diseases. The results of our survey confirm that the TÄHAV amendment is having a positive impact on prudent antibiotic use, with participants performing more ASTs, using HPCIA less frequently, and choosing alternative antimicrobials for therapy.

Antimicrobial Prodrug Activation by the Staphylococcal Glyoxalase GloB

With the rising prevalence of multidrug resistance, there is an urgent need to develop novel antibiotics. Many putative antibiotics demonstrate promising in vitro potency but fail in vivo due to poor drug-like qualities (e.g., serum half-life, oral absorption, solubility, and toxicity). These drug-like properties can be modified through the addition of chemical protecting groups, creating "prodrugs" that are activated prior to target inhibition. Lipophilic prodrugging techniques, including the attachment of a pivaloyloxymethyl group, have garnered attention for their ability to increase cellular permeability by masking charged residues and the relative ease of the chemical prodrugging process. Unfortunately, pivaloyloxymethyl prodrugs are rapidly activated by human sera, rendering any membrane permeability qualities absent during clinical treatment. Identification of the bacterial prodrug activation pathway(s) will allow for the development of host-stable and microbe-targeted prodrug therapies. Here, we use two zoonotic staphylococcal species, Staphylococcus schleiferi and S. pseudintermedius, to establish the mechanism of carboxy ester prodrug activation. Using a forward genetic screen, we identify a conserved locus in both species encoding the enzyme hydroxyacylglutathione hydrolase (GloB), whose loss-of-function confers resistance to carboxy ester prodrugs. We enzymatically characterize GloB and demonstrate that it is a functional glyoxalase II enzyme, which has the capacity to activate carboxy ester prodrugs. As GloB homologues are both widespread and diverse in sequence, our findings suggest that GloB may be a useful mechanism for developing species- or genus-level prodrug targeting strategies.

Potent, specific MEPicides for treatment of zoonotic staphylococci

Coagulase-positive staphylococci, which frequently colonize the mucosal surfaces of animals, also cause a spectrum of opportunistic infections including skin and soft tissue infections, urinary tract infections, pneumonia, and bacteremia. However, recent advances in bacterial identification have revealed that these common veterinary pathogens are in fact zoonoses that cause serious infections in human patients. The global spread of multidrug-resistant zoonotic staphylococci, in particular the emergence of methicillin-resistant organisms, is now a serious threat to both animal and human welfare. Accordingly, new therapeutic targets that can be exploited to combat staphylococcal infections are urgently needed. Enzymes of the methylerythritol phosphate pathway (MEP) of isoprenoid biosynthesis represent potential targets for treating zoonotic staphylococci. Here we demonstrate that fosmidomycin (FSM) inhibits the first step of the isoprenoid biosynthetic pathway catalyzed by deoxyxylulose phosphate reductoisomerase (DXR) in staphylococci. In addition, we have both enzymatically and structurally determined the mechanism by which FSM elicits its effect. Using a forward genetic screen, the glycerol-3-phosphate transporter GlpT that facilitates FSM uptake was identified in two zoonotic staphylococci, Staphylococcus schleiferi and Staphylococcus pseudintermedius. A series of lipophilic ester prodrugs (termed MEPicides) structurally related to FSM were synthesized, and data indicate that the presence of the prodrug moiety not only substantially increased potency of the inhibitors against staphylococci but also bypassed the need for GlpT-mediated cellular transport. Collectively, our data indicate that the prodrug MEPicides selectively and robustly inhibit DXR in zoonotic staphylococci, and further, that DXR represents a promising, druggable target for future development.

Contamination of the urban environment with excrements of companion animals as an underestimated source of Staphylococcus species posing a threat to public health

The aim of the study was to assess the incidence, resistance, virulence, and genotypic characteristics of Staphylococcus spp. residing in the gastrointestinal tract of dogs and cats, as a group of animals causing potential contamination of the urban space. A high percentage of strains resistant to penicillin (58%), oxacillin (9%) and tetracycline (60%) were found. All isolates resistant to penicillin, kanamycin, or chloramphenicol carried genes responsible for individual resistance (blaZ, aph(3')-IIIa, and cat (pC194)/cat (pC223), respectively. The mecA gene was detected in 45% of the oxacillin-resistant Staphylococcus pseudintermedius strains. The amplification of DNA fragments surrounding rare restriction sites analysis demonstrated high heterogeneity of genotypic profiles correlating with phenotypic resistance profiles. Multilocus sequence typing analysis classified the methicillin-resistant S. pseudintermedius strains as ST71, ST890, and the totally new ST1047. The presence of a high level of resistance among Staphylococcus strains may suggest a potential risk of transfer of these bacteria between companion animals and humans.

Efficacy study of a topical treatment with a plant extract with antibiofilm activities using an in vivo model of canine superficial pyoderma

BACKGROUND

Canine pyoderma is a common skin infection caused predominantly by staphylococcal bacteria. Because of increasing rates of antimicrobial resistance in bacterial isolates, there is an urgent need for alternative or supplementary treatment options. W16P576, a Water Extract of Complex Mix of Edible Plants (WECMEP), has shown in vitro activity against a variety of bacteria, including Staphylococcus pseudintermedius. A canine model of pyoderma was developed which allows in vivo testing of antimicrobial agents in a controlled environment.

OBJECTIVE

To evaluate the antibacterial efficacy of topical application of W16P576 in a model of canine pyoderma.

ANIMALS

Nine laboratory housed beagle dogs.

METHODS AND MATERIALS

In an evaluator-blinded cross-over study with an eight week washout period, dogs were treated topically twice daily with W16P576 WECMEP or its vehicle, starting three days before bacterial challenge. On the day of challenge, each dog was treated with two concentrations of a clinical S. pseudintermedius strain on opposite sides of the body. Topical treatment was continued for 11 days and lesions of pyoderma were evaluated and scored for 14 days.

RESULTS

All dogs developed lesions consistent with bacterial pyoderma. Lesion scores were generally higher on the side inoculated with a higher concentration of bacteria. Treatment with W16P576 significantly reduced lesion development and hastened resolution of lesions, compared to placebo.

CONCLUSION

Topical application of W16P576 markedly reduced lesion development in this proof of principle study. Clinical trials are warranted to estimate benefits for dogs with naturally occurring pyoderma under field conditions.

Medicinal plants as therapeutic options for topical treatment in canine dermatology? A systematic review

Background

Medicinal plants have been used traditionally since centuries for wound care and treatment of skin diseases both in human and animals. Skin diseases are one of the most common reasons for owners to take their dog to the veterinarian. The demands for treatment and prophylaxis of these diseases are broad. A wide range of bacteria including antibiotic-resistant bacteria can be involved, making the treatment challenging and bear an anthropo-zoonotic potential. The aim of this review is to systematically evaluate based on recent scientific literature, the potential of four medicinal plants to enrich the therapeutic options in pyoderma, canine atopic dermatitis, otitis externa, wounds and dermatophytosis in dogs.

Results

Based on four books and a survey among veterinarians specialized in phytotherapy, four medicinal plants were chosen as the subject of this systematic review: Calendula officinalis L. (Marigold), Hypericum perforatum L. agg. (St. John’s Wort), Matricaria chamomilla L. (syn. Matricaria recutita L., Chamomile) and Salvia officinalis L. (Sage). According to the PRISMA statement through literature research on two online databases a total of 8295 publications was screened and narrowed down to a final 138 publications for which full-text documents were analyzed for its content resulting in a total of 145 references (21 clinical, 24 in vivo and 100 in vitro references).

Conclusions

All four plants were proven to have antibacterial and antifungal effects of a rather broad spectrum including antibiotic-resistant bacteria. This makes them an interesting new option for the treatment of pyoderma, otitis externa, infected wounds and dermatophytosis. Marigold, St. John’s Wort and Chamomile showed wound-healing properties and are thus promising candidates in line to fill the therapeutic gap in canine wound-healing agents. St. John’s Wort and Chamomile also showed anti-inflammatory and other beneficial effects on healthy skin. Due to the wide range of beneficial effects of these medicinal plants, they should be taken into account for the treatment of dermatologic diseases in dogs at least in future clinical research.

Electronic supplementary material

The online version of this article (10.1186/s12917-019-1854-4) contains supplementary material, which is available to authorized users.

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.

Occurrence and characterization of methicillin-resistant Staphylococcus pseudintermedius in successive parturitions of bitches and their puppies in two kennels in Italy

BACKGROUND

Multi-drug methicillin-resistant Staphylococcus pseudintermedius (MRSP) detection is rapidly increasing in microbial specimens from pets across Europe. MRSP has also been isolated from bitches and newborns in dog breeding kennels. This study assessed whether MRSP lineage differs between breeding kennels and is maintained over time. Post-partum bitches (at day 3 vaginal and day 3, 9 and 35 milk samples) and their litters (at day 3, 9 and 35 oral and abdominal skin samples) from two Italian breeding kennels (A and B) were sampled and MRSP was subsequently characterized via whole-genome sequencing and antibiotic susceptibility testing. The study was carried out from October 2014 to March 2016 and included successive parturitions from the same animals.

RESULTS

The analysis revealed different situations in both investigated kennels. In kennel A, circulating strains were from 7-locus sequence types ST688, ST258 and closely related isolates of ST71, which included most isolates. In kennel B, only a new isolate, ST772, was detected. In addition, most isolates from both kennels had multi-resistant antibiotic profiles. MRSP was only isolated from litters of MRSP-positive bitches, thus suggesting that bitch-litter transmission is likely.

CONCLUSIONS

Our data show that MRSP circulation can differ in different settings, that several clonal lineages can circulate together, and that vertical transmission appears common. MRSP colonization did not affect the health conditions of the bitches or of their litters.

Characterization, distribution, antimicrobial resistance and resistance risk factors in staphylococci isolated from cats from 2001 to 2014

Relatively few studies have been published describing the patterns of staphylococcal isolation and antimicrobial resistance over time in cats. The objective of this retrospective study was to determine the frequency, location, characteristics and antimicrobial resistance profiles of staphylococci isolated by the Louisiana Animal Disease Diagnostic Laboratory between the years 2001 and 2014. All feline staphylococcal isolates were classified phenotypically. Isolates corresponding to known or possibly pathogenic species (Staphylococcus intermedius group (SIG) and Staphylococcus aureus (SA)) as well as Staphylococcus epidermidis (SE) and non‐speciated coagulase‐negative staphylococci (CNS) were further evaluated to determine antimicrobial resistance patterns. A total of 519 staphylococci were isolated. The largest percentage of isolates was CNS, representing 39.3% of the total, while SIG, SE, SA and non‐speciated coagulase positive staphylococci (CPS) represented 18.1%, 10.2%, 8.3% and 7.3%, respectively. Methicillin resistance (MR) was identified in 57.1% of SA and 20.5% of SIG. Resistance to 3 or more antimicrobial classes (multidrug resistance; MDR) was demonstrated in 54.5% of SA and 23.9% of SIG. The prevalence of MDR increased over time in both SIG and SA, while the prevalence of MR increased over time in SIG. An increase in mean antimicrobial resistance score over time was seen in SIG. This study demonstrates a high and increasing prevalence of MDR in SIG and SA, as well as increasing prevalence of MR in SIG isolated from cats.

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.

Pet owner and vet interactions: exploring the drivers of AMR

Background

Antimicrobial resistance (AMR) is a growing public health problem across the world. As the negative consequences of AMR become apparent at local, national and international levels, more attention is being focussed on the variety of mechanisms by which AMR is potentiated. We explore how interactions between pet owners and veterinarians represent a key arena in which AMR-related behaviours can be shaped.

Methods

In depth semi-structured interviews were carried out with pet owners (n = 23) and vets (n = 16) across the UK in 2017. A thematic analysis approach was taken, with inductively gathered data analysed deductively using a behavioural framework to identified key behaviours emerging from participant accounts which were amenable to change.

Results

Interactions between vets and pet owners were characterised by misunderstandings and misconceptions around antibiotics by pet owners, and a lack of clarity about the positions and intentions of the other party. Vets and pet owners had differing perceptions of where pressure to prescribe antibiotics inappropriately originated. Vets perceived it was mostly pet owners who pushed for inappropriate antibiotics, whereas pet owners reported they felt it was vets that overprescribed. Low levels of understanding of AMR in general were apparent amongst pet owners and understandings with regard to AMR in pets specifically were almost non-existent in the sample.

Conclusions

Improved use of antibiotics could be assisted by educating the pet owning public and by guideline development for companion animal vets, concurrent development of mandatory legislation, increased consultation time to facilitate better communication, development of vet training on antimicrobial therapy and stewardship led interactions with pet owners, and increased levels of knowledge of pet-related AMR amongst pet owners.

Expression and function of protein A in Staphylococcus pseudintermedius

Staphylococcus pseudintermedius is an opportunistic pathogen in dogs and the most frequent cause of canine pyoderma. Protein A, a potent virulence factor in S. aureus is encoded by the spa gene. S. pseudintermedius possesses genes seemingly analogous to spa, but the expression and the characteristics of their products have not been directly determined. The purpose of this study was to test isolates from major clonal groups for the presence of spa gene orthologs, quantitate their expression levels, and to characterize protein A in S. pseudintermedius.  From the data, it was observed that S. pseudintermedius isolates express genes analogous to spa in S. aureus. Isolates representing major clonal populations in the United States and Europe, ST68 and ST71 respectively, bound significantly higher amounts of canine IgG than isolates with other genetic backgrounds, suggesting that these isolates have a higher density of protein A on their surface. Also, canine IgG bound to protein A on S. pseudintermedius via its Fc region similar to protein A from S. aureus. The mRNA profile differed based on the bacterial sequence types and correlated to the density of protein A on the bacterial surface. Protein A was also found to be secreted during the exponential growth phase. Phagocytosis experiments with S. pseudintermedius show that blocking of protein A enhanced phagocytosis in whole blood, neutrophils and in DH82 canine macrophage-like cell line. Taken together, the results demonstrate that S. pseudintermedius produces protein A that shares S. aureus protein A's ability to bind the Fc region of immunoglobulins and may serve as a potential virulence factor by evading the host immune system.

Short and long-term outcome following surgical stabilization of tarsocrural instability in dogs

Objectives: To evaluate the outcome and complications following surgical stabilization of canine tarsocrural luxations.

Methods: Medical records of dogs which were surgically treated for tarsocrural joint instability between February 2007 and June 2014 were reviewed. Surgical technique, complications and long-term outcome (via questionnaire and Canine Brief Pain Inventory) were assessed.

Results: Twenty-four dogs (26 joints) were included. All injuries were traumatic. All joints had associated fractures; malleolar in 21/26 limbs (13/26 medial). Eight joints had internal fracture fixation and transarticular external skeletal fixator, six had external fixator alone, four had prosthetic ligaments with external fixator, and four had prosthetic ligaments with external coaptation. Two joints had pantarsal arthrodesis and two primary ligament repair. Complications occurred in 24/26 limbs giving 45 distinct complications; 16 were minor, 29 major, and 31 complications were external fixator associated. Prosthetic ligaments were significantly associated with major complications (p = 0.017); five out of eight required subsequent removal between 105–1006 days. Cost was significantly associated with major complications (p = 0.017) and soft tissue wounds (p = 0.03). Long-term lameness was seen in nine of 14 dogs. There was no association between pain severity (p = 0.3) and pain interference scores (p = 0.198) when comparing stabilization methods.

Clinical significance: Complications are common; however many are external fixator related. Prosthetic ligaments are significantly associated with major complications. Regardless of technique, a degree of ongoing lameness is likely.

Moving from information and collaboration to action: report from the 3rd International Dog Health Workshop, Paris in April 2017

BACKGROUND

Breed-related health problems in dogs have received increased focus over the last decade. Responsibility for causing and/or solving these problems has been variously directed towards dog breeders and kennel clubs, the veterinary profession, welfare scientists, owners, regulators, insurance companies and the media. In reality, all these stakeholders are likely to share some responsibility and optimal progress on resolving these challenges requires all key stakeholders to work together. The International Partnership for Dogs (IPFD), together with an alternating host organization, holds biennial meetings called the International Dog Health Workshops (IDHW). The Société Centrale Canine (French Kennel Club) hosted the 3rd IDHW, in Paris, in April, 2017. These meetings bring together a wide range of stakeholders in dog health, science and welfare to improve international sharing of information and resources, to provide a forum for ongoing collaboration, and to identify specific needs and actions to improve health, well-being and welfare in dogs.

RESULTS

The workshop included 140 participants from 23 countries and was structured around six important issues facing those who work to improve dog health. These included individualized breed-specific strategies for health and breeding, extreme conformations, education and communication in relation to antimicrobial resistance, behavior and welfare, genetic testing and population-based evidence. A number of exciting actions were agreed during the meeting. These included setting up working groups to create tools to help breed clubs accelerate the implementation of breed-health strategies, review aspects of extreme conformation and share useful information on behavior. The meeting also heralded the development of an online resource of relevant information describing quality measures for DNA testing. A demand for more and better data and evidence was a recurring message stressed across all themes.

CONCLUSIONS

The meeting confirmed the benefits from inclusion of a diverse range of stakeholders who all play relevant and collaborative parts to improve future canine health. Firm actions were set for progress towards improving breed-related welfare. The next international workshop will be in the UK in 2019 and will be organized by the UK Kennel Club.

Recommendations for approaches to meticillin-resistant staphylococcal infections of small animals: diagnosis, therapeutic considerations and preventative measures.: Clinical Consensus Guidelines of the World Association for Veterinary Dermatology

BACKGROUND

Multiple drug resistance (MDR) in staphylococci, including resistance to the semi-synthetic penicillinase-resistant penicillins such as meticillin, is a problem of global proportions that presents serious challenges to the successful treatment of staphylococcal infections of companion animals.

OBJECTIVES

The objective of this document is to provide harmonized recommendations for the diagnosis, prevention and treatment of meticillin-resistant staphylococcal infections in dogs and cats.

METHODS

The authors served as a Guideline Panel (GP) and reviewed the literature available prior to September 2016. The GP prepared a detailed literature review and made recommendations on selected topics. The World Association of Veterinary Dermatology (WAVD) provided guidance and oversight for this process. A draft of the document was presented at the 8th World Congress of Veterinary Dermatology (May 2016) and was then made available via the World Wide Web to the member organizations of the WAVD for a period of three months. Comments were solicited and posted to the GP electronically. Responses were incorporated by the GP into the final document.

CONCLUSIONS

Adherence to guidelines for the diagnosis, laboratory reporting, judicious therapy (including restriction of use policies for certain antimicrobial drugs), personal hygiene, and environmental cleaning and disinfection may help to mitigate the progressive development and dissemination of MDR staphylococci.

A survey of methods used for antimicrobial susceptibility testing in veterinary diagnostic laboratories in the United States

Antimicrobial resistance is a serious threat to animal and human health worldwide, requiring a collaborative, holistic approach. The U.S. Government has developed a national strategy to address antimicrobial resistance, with one component being to monitor antimicrobial resistance in agricultural settings. We developed a survey to collect information about antimicrobial susceptibility testing (AST) from the veterinary diagnostic laboratory community in the United States, assessing current practices and technologies and determining how AST information is shared. Of the 132 surveys administered, 52 (39%) were returned. Overall, responding laboratories conducted susceptibility tests on 98,788 bacterial isolates in 2014, with Escherichia coli being the most common pathogen tested across all animal species. The 2 most common AST methods employed were the disk diffusion method (71%) and the Sensititre platform broth microdilution system (59%). Laboratories primarily used the Clinical Laboratory Standards Institute (CLSI) VET-01 standard (69%) and the automatically calculated interpretations provided by the commercial AST systems (61%) for interpreting their AST data. Only 22% of laboratories published AST data on a periodic basis, usually via annual reports published on the laboratory's website or through peer-reviewed journals for specific pathogens. Our results confirm that disk diffusion and broth microdilution remain the standard AST methods employed by U.S. veterinary diagnostic laboratories, and that CLSI standards are commonly used for interpreting AST results. This information will help determine the most efficient standardized methodology for future surveillance. Furthermore, the current infrastructure within laboratories, once harmonized, will help provide a mechanism for conducting national surveillance programs.

Antimicrobial resistance in Staphylococcus pseudintermedius and the molecular epidemiology of methicillin-resistant S. pseudintermedius in small animals in Finland

Objectives

To investigate antimicrobial susceptibility in Staphylococcus pseudintermedius and the occurrence of methicillin-resistant S. pseudintermedius (MRSP), to explore the molecular structure of the MRSP population and to analyse risk factors for MRSP.

Methods

Susceptibility data for clinical S. pseudintermedius isolates in 2011-15 were analysed using WHONET. All MRSP isolates in 2010-14 ( n  =   362) were typed using PFGE. Representative isolates ( n  =   87) of clusters were analysed using MLST and staphylococcal cassette chromosome mec (SCC mec ) typing. Risk factors were analysed using logistic regression.

Results

Of the clinical S. pseudintermedius ( n  =   1958; 98% from dogs), 14% were MRSP. Resistance to other antimicrobials varied between 12% and 39%. No trends were observed over time. Among clinical specimens (from infection sites) and screening specimens (from potential carriers), respectively, 2.5% (267/10 813) and 9% (211/2434) revealed MRSP. MLST revealed 42 different STs, including 19 new ones. Clonal complexes 71, 45 and 258 were the most common, but the MRSP population diversified over the years. A clinical S. pseudintermedius isolate was more likely to be MRSP if the patient was on antimicrobials at the time of sampling or was male. The presence of MRSP in screening specimens was more likely if the patient was on multiple antimicrobials at the time of sampling. Specimens from private clinics (versus the Veterinary Teaching Hospital of the University of Helsinki) had a higher likelihood of MRSP in both analyses.

Conclusions

Resistance to antimicrobials among S. pseudintermedius in Finland is high, emphasizing the importance of infection control measures and susceptibility testing prior to therapy. The diverse MRSP population indicates non-clonal spread.

Establishing a canine superficial pyoderma model

AIMS

Pyoderma, predominantly associated with Staphylococcus pseudintermedius, is a common skin infection of dogs that typically requires long-lasting treatments, complicated by increasing antimicrobial resistance. To investigate new treatment strategies, we aimed at establishing a dog model of pyoderma that closely mimics the natural disease.

METHODS AND RESULTS

We inoculated six laboratory beagles with a methicillin-susceptible strain of S. pseudintermedius. One millilitre of approximately 10⁷ , 10⁸ , 10⁹ CFU per ml was topically applied onto clipped and tape stripped area of dog skin, which was then treated with a dermaroller (microneedle size: 500 μm) immediately after administration. Dogs were monitored daily, suspect pustules were cultured for S. pseudintermedius and evaluated by cytological and histopathological methods. After 24 h, all dogs developed papules and pustules at all three bacterial inoculation sites, which worsened over the next 48 h. Cytological samples of all skin lesions revealed neutrophils with intracellular cocci. Histopathology confirmed subcorneal neutrophilic pustular dermatitis with intralesional cocci and acantholytic keratinocytes, consistent with superficial pyoderma. Staphylococcus pseudintermedius was isolated from pustules of all dogs and confirmed to be the inoculating strain. The results were replicated in all dogs after a wash out period of 6 weeks.

CONCLUSIONS

These data demonstrate the feasibility of establishing a dog model of pyoderma.

SIGNIFICANCE AND IMPACT OF THE STUDY

The new model can be used to evaluate novel prevention and treatment options for canine pyoderma.

Antimicrobial Susceptibility Monitoring of Bacterial Pathogens Isolated from Urinary Tract Infections in Dogs and Cats Across Europe: ComPath Results

ComPath is a pan-European antimicrobial surveillance program collecting bacterial pathogens from dogs and cats not recently exposed to antimicrobials. We present minimum inhibitory concentration data obtained using Clinical and Laboratory Standards Institute methodology for 616 urinary tract infection (UTI) isolates collected between 2008 and 2010. In both dogs and cats, the most common pathogen was Escherichia coli (59.8% and 46.7%, respectively). Antimicrobial activity against E. coli in dogs and cats was similar with fluoroquinolone and trimethoprim/sulfamethoxazole susceptibility >90%. Ampicillin susceptibility was ∼80%. Staphylococcus intermedius Group isolates from dogs (67/437, 15.3%) had high antimicrobial susceptibility (>90%) toward beta-lactams, fluoroquinolones, and trimethoprim/sulfamethoxazole. Four canine isolates (6%) were oxacillin resistant, and harbored mecA. Proteus mirabilis from dogs (48/437, 11.0%) had high antimicrobial susceptibility (∼90%) to amoxicillin/clavulanic acid, enrofloxacin, and marbofloxacin and slightly lower susceptibility (∼80-85%) to ampicillin and orbifloxacin. Streptococcus canis isolates (35/437, 8.0%) from dogs were all susceptible to ampicillin and amoxicillin/clavulanic acid and >90% susceptible to marbofloxacin. Although resistance was not observed, high intermediate susceptibility was seen for both enrofloxacin (28.6%) and orbifloxacin (85.7%). Overall, antimicrobial in vitro activity appears to be high in UTI pathogens from dogs and cats with low multidrug resistance, although a lack of specific dog and cat breakpoints for important antimicrobials such as cefovecin, cephalexin, and ibafloxacin prevents analysis of susceptibility for these agents.

Human infections due to Staphylococcus pseudintermedius, an emerging zoonosis of canine origin: report of 24 cases

BACKGROUND

Staphylococcus pseudintermedius has been recently identified as a novel species within the genus Staphylococcus, and is commonly associated with infections in dogs. Currently, there are few reports of human infections due to this bacterium.

OBJECTIVE

To use a population-based approach to describe the characteristics of human S. pseudintermedius infections in a large Canadian healthcare region.

METHODS

All adult cases aged ≥18 years identified at a large regional laboratory from April 1, 2013 to April 1, 2015 who had at least one positive culture for S. pseudintermedius were retrospectively reviewed. A combination of phenotypic methods, mass spectrometry (i.e., MALDI-TOF), and cpn60 sequencing were used to identify S. pseudintermedius. Chart review was conducted, and cases were analysed descriptively.

RESULTS

Twenty-seven isolates of S. pseudintermedius from 24 human cases were included for analysis. 58.3% were male with median age of 61 years (IQR 55-70.5). Most patients [22 (92.1%)] had confirmed contact with dogs at time of infection. S. pseudintermedius was isolated in 18 cases (75.0%) of skin and soft tissue infections (SSTI), and 2 invasive cases (8.3%) including a prosthetic joint and bloodstream infection. The other 4 patients were considered to be colonized (skin - 3; lung - 1). Methicillin resistance was identified in 3 cases with 6 total isolates (22.2%); multi-drug resistance was also demonstrated commonly.

CONCLUSION

S. pseudintermedius is most commonly associated with SSTIs in humans. Transmission probably occurs from a pet dog. Species-level identification of S. pseudintermedius is important due to the high prevalence of antibiotic resistance, particularly to methicillin.

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.

Trends and molecular mechanisms of antimicrobial resistance in clinical staphylococci isolated from companion animals over a 16 year period

OBJECTIVES

The objective of this study was to investigate the evolution of resistance to antimicrobials, corresponding mechanisms and molecular characteristics of Staphylococcus spp., between 1999 and 2014.

METHODS

Susceptibility to 38 antimicrobials was determined for 632 clinical staphylococcal isolates obtained from companion animals (dogs, cats, horses and other animals). Twenty antimicrobial resistance genes, including mecA and mecC, were screened by PCR. Methicillin-resistant staphylococci were characterized by spa (Staphylococcus aureus), SCCmec, MLST and PFGE typing. Statistical analyses were performed using SAS v9.3 and differences were considered relevant if P ≤ 0.05.

RESULTS

The mecA gene was identified in 74 staphylococcal isolates (11.6%): 11 MRSA (40.7%), 40 methicillin-resistant Staphylococcus pseudintermedius (MRSP; 8.7%) and 23 methicillin-resistant CoNS (26.7%). Resistance to the majority of antimicrobials and the number of mecA-positive isolates increased significantly over time. Eighteen spa types were identified, including two new ones. MRSA isolates were divided into three PFGE clusters that included ST22-IV, ST105-II, ST398-V and ST5-VI. Most methicillin-resistant Staphylococcus epidermidis isolates were of clonal complex (CC) 5, including a new ST, and clustered in eight PFGE clusters. MRSP were grouped into five PFGE clusters and included ST45-NT, ST71-II-III, ST195-III, ST196-V, ST339-NT, ST342-IV and the new ST400-III. Methicillin-resistant Staphylococcus haemolyticus clustered in two PFGE clusters.

CONCLUSIONS

The significant increase in antimicrobial-resistant and mecA-positive isolates in recent years is worrying. Furthermore, several isolates are MDR, which complicates antimicrobial treatment and increases the risk of transfer to humans or human isolates. Several clonal lineages of MRSA and methicillin-resistant S. epidermidis circulating in human hospitals and the community were found, suggesting that companion animals can become infected with and contribute to the dissemination of highly successful human clones. Urgent measures, such as determination of clinical breakpoints and guidelines for antimicrobial use, are needed.