Panton-Valentine Leukocidin-Positive Staphylococcus aureus in Family and Pet Cat.

Continued detection of Panton-Valentine leukocidin-positive Staphylococcus aureus in samples from a family with severe repeated skin infections and their pet cat suggests transmission between the family and the cat. Decolonizing the pet led to successful elimination of the bacteria from the household. Clinicians should consider pet cats as possible reinfection sources.

Rifampicin treatment of canine multidrug-resistant meticillin-resistant staphylococcal pyoderma: A retrospective study of 51 cases.

BACKGROUND: Rifampicin (RFP) is a potential treatment for canine multidrug-resistant (MDR) meticillin-resistant staphylococci (MRS), yet the use of lower doses based on recent MIC data has not been evaluated in vivo. HYPOTHESIS/OBJECTIVES: To provide information on the efficacy and safety of low-dose range RFP (≤6 mg/kg/day) for the treatment of canine MDR MRS pyoderma. ANIMALS: Fifty-one client-owned dogs. MATERIALS AND METHODS: Retrospective review of dogs medical records. Dogs were from 11 US dermatology referral practices and had oral RFP at ≤6 mg/kg/day. Data evaluated included response to treatment, adverse events, and serum changes in alanine aminotransferase (ALT) and alkaline phosphatase (ALP). RESULTS: Complete resolution of pyoderma occurred in 39 of 51 dogs (76.5%). Topical antimicrobials were used concurrently in most cases (47 of 51; 92.2%). ALP elevation >1.5-fold of baseline or the high end of the reference range occurred in nine of 37 (24.3%) dogs, while ALT elevation above baseline and the high end of the reference range occurred in two of 36 (5.6%). Only six of 51 (11.8%) had clinical adverse events during treatment; five of six (83.3%) were mild reactions consisting of lethargy and gastrointestinal signs, while one dog had a possible cutaneous adverse drug reaction. Of those that experienced clinical adverse events, four of six (66.7%) did not have concurrent increased liver enzyme activity, while two of six (33.3%) had elevations in ALP alone. CONCLUSIONS AND CLINICAL RELEVANCE: Low-dose RFP (≤6 mg/kg/day) appears to be a relatively safe and effective single-agent systemic antibiotic in combination with topical antimicrobials for canine MDR MRS pyoderma.

CONTEXTE: La rifampicine (RFP) est un traitement potentiel des staphylocoques canins multirésistants (MDR) résistants à la méticilline (MRS), mais l'utilisation de doses plus faibles sur la base de données récentes sur la CMI n'a pas été évaluée in vivo. Hypothèse/Objectifs : Fournir des informations sur l'efficacité et l'innocuité des RFP à faible dose (≤ 6 mg/kg/jour) pour le traitement de la pyodermite MDR-MR canine. Animaux : Cinquante et un chiens de propriétaires. Matériels et méthodes : Revue rétrospective de chiens ayant reçu RFP par voie orale à des doses ≤ 6 mg/kg/jour provenant des dossiers médicaux de 11 centres de référés en dermatologie aux États-Unis. Les données évaluées comprenaient la réponse au traitement, les événements indésirables et les modifications sériques de l'alanine aminotransférase (ALT) et de la phosphatase alcaline (ALP). Résultats : Une résolution complète de la pyodermite s'est produite chez 39 des 51 chiens (76,5 %). Des antimicrobiens topiques ont été utilisés simultanément dans la plupart des cas (47 sur 51 ; 92,2 %). Une élévation de l'ALP> 1,5 fois la ligne de base ou l'extrémité supérieure de la plage de référence s'est produite chez neuf des 37 (24,3%) chiens, tandis qu'une élévation de l'ALT au-dessus de la ligne de base et de l'extrémité supérieure de la plage de référence s'est produite chez deux des 36 (5,6%). Seuls six sur 51 (11,8 %) ont eu des événements indésirables cliniques pendant le traitement ; cinq des six (83,3 %) étaient des réactions bénignes consistant en une léthargie et des signes gastro-intestinaux, tandis qu'un chien a eu un possible effet indésirable cutané au médicament. Parmi ceux qui ont subi des événements indésirables cliniques, quatre sur six (66,7 %) n'ont pas eu d'augmentation simultanée de l'activité des enzymes hépatiques, tandis que deux sur six (33,3 %) ont présenté des élévations de l'ALP seule. Conclusions et pertinence clinique : La RFP à faible dose (≤ 6 mg/kg/jour) semble être un antibiotique systémique à agent unique relativement sûr et efficace en association avec des antimicrobiens topiques pour la pyodermite MDR MRS canine.

Introducción- la rifampicina (RFP) es un tratamiento potencial para los estafilococos resistentes a múltiples fármacos (MDR) y meticilina (MRS), sin embargo, el uso de dosis más bajas basado en datos recientes de MIC no se ha evaluado in vivo. Hipótesis/Objetivos- Proporcionar información sobre la eficacia y seguridad de RFP en el rango de dosis bajas (≤6 mg/kg/día) para el tratamiento de la pioderma canina MDR MRS. Animales- Cincuenta y un perros propietarios particulares. Materiales y métodos- revisión retrospectiva de perros que recibieron RFP oral a dosis ≤6 mg/kg/día obtenida de historiales clínicos de 11 prácticas de referencia de dermatología de los Estados Unidos. Los datos evaluados incluyeron la respuesta al tratamiento, los eventos adversos y los cambios séricos en la alanina aminotransferasa (ALT) y la fosfatasa alcalina (ALP). Resultados- una resolución completa de la pioderma ocurrió en 39 de 51 perros (76,5 %). Antimicrobianos tópicos se usaron al mismo tiempo en la mayoría de los casos (47 de 51; 92,2%). En nueve de 37 (24,3 %) perros se produjo una elevación de ALP >1,5 veces respecto al valor inicial o el extremo superior del rango de referencia, mientras que en dos de 36 (5,6 %) se produjo una elevación de ALT por encima del valor inicial y en el límite superior del rango de referencia. Solo seis de 51 (11,8%) tuvieron eventos adversos clínicos durante el tratamiento; cinco de seis (83,3 %) fueron reacciones leves que consistieron en letargo y signos gastrointestinales, mientras que un perro tuvo una posible reacción cutánea adversa al medicamento. De los que experimentaron eventos adversos clínicos, cuatro de seis (66,7 %) no tuvieron un aumento simultáneo de la actividad de las enzimas hepáticas, mientras que dos de seis (33,3 %) tuvieron elevaciones en la ALP por sí sola. Conclusiones y relevancia clínica- la dosis baja de RFP (≤6 mg/kg/día) parece ser un antibiótico sistémico de uso único relativamente seguro y efectivo en combinación con antimicrobianos tópicos para la pioderma canina MDR MRS.

Contexto - A rifampicina (RFP) é um tratamento potencial para estafilococos resistentes à meticilina (MRS) multirresistentes (MDR) e a utilização de doses mais baixas baseado em dados recentes de MIC não foi avaliada in vivo. Hipótese/Objetivos: Fornecer informações sobre a eficácia e segurança de RFP em menor dosagem (≤6 mg/kg/dia) para o tratamento de piodermite canina por MRS MDR. Animais: Cinquenta e um cães de clientes. Materiais e métodos: Uma revisão retrospectiva dos prontuários de cães que receberam RFP oral na dose de ≤6 mg/kg/dia em 11 clínicas dermatológicas nos Estados Unidos. Os dados avaliados incluíram resposta ao tratamento, eventos adversos, alterações séricas de alanina aminotransferase (ALT) e fosfatase alcalina (FA). Resultados: Resolução completa da piodermite ocorreu em 39 de 51 dos cães (76,5%). Antimicrobianos tópicos foram utilizados concomitantemente na maioria dos casos (47 de 51; 92,2%). Elevação de mais de 1,5 vezes na FA ou para o limite superior do intervalo de referência ocorreu em nove de 37 cães (24,3%), enquanto a elevação de ALT acima do valor inicial e o limite superior do valor de referência ocorreu em dois de 36 (5,6%). Apenas cinco de 51 (11,8%) apresentaram efeitos adversos durante o tratamento; cinco de seis (83,3%) tiveram reações leves caracterizadas por letargia e sinais gastrointestinais, enquanto um cão apresentou uma possível farmacodermia. Dos que apresentaram eventos adversos, quatro de seis (66,7%) não apresentaram aumento concomitante de enzimas hepáticas, enquanto dois de seis (33,3%) tiveram aumento de FA isoladamente. Conclusões e relevância clínica - RFP em baixa dosagem (≤6 mg/kg/dia) aparenta ser relativamente segura e eficaz em monoterapia no tratamento da piodermite canina por MRS MDR por via sistêmica, associada a antimicrobianos tópicos.

Recovery of meticillin-resistant Staphylococcus species from pet-grooming salons.

BACKGROUND: Meticillin-resistant (MR) staphylococcal species have been cultured from veterinary hospital environments and veterinary instruments. Pet-grooming salon environments and grooming tools may pose a risk for dissemination of MR staphylococcal bacteria into the pet population. OBJECTIVE: The objectives of this study were to investigate the frequency of MR staphylococcal colonization of pet-grooming salons and to collect information regarding cleaning procedures in grooming salons. METHODS AND MATERIALS: A nonrandomized, observational study was performed in 2018. Locations inside 19 grooming salons near Tacoma, WA, USA, were sampled and selectively cultured for MR, coagulase-positive staphylococci. Sampled sites included clipper blades and handles, leashes, rims of bathtub drains, insides of shampoo caps, and bathtub spray hoses or faucet handles. Grooming salons were asked to complete surveys regarding their cleaning practices. RESULTS: Meticillin-resistant coagulase-positive staphylococci were isolated from 12 of 19 grooming salons and 25 of 112 total samples. Meticillin-resistant S. pseudintermedius, S. aureus and S. schleiferi were isolated from multiple salons, most commonly from electric clipper blades, clipper handles and grooming leashes. No statistically significant correlations were identified between cleaning practices and the isolation of MR coagulase-positive staphylococci. CONCLUSIONS AND CLINICAL IMPORTANCE: Clipper blades, clipper handles and leashes are potential fomites for MR staphylococci in a grooming salon; increased disinfection practices for these items are indicated. A prospective, controlled, large-scale study is warranted to examine the effect of grooming salon hygiene practices on the isolation of MR staphylococci in salons.

Antibody levels to Malassezia pachydermatis and Staphylococcus pseudintermedius in atopic dogs and their relationship with lesion scores.

BACKGROUND: Elevated immunoglobulin E (IgE) levels to Malassezia or Staphylococcus species in human atopic dermatitis are related to the skin severity index; a similar association has not been reported in atopic dogs. OBJECTIVES: To investigate serum levels of allergen-specific IgE, total specific IgG and IgG subclasses (IgG1 and IgG2) for M. pachydermatis and S. pseudintermedius, and to correlate them with the severity of dermatitis in dogs. ANIMALS: Serum samples were collected from dogs categorized by age and disease status. Groups 1 and 2: <3-year-old healthy (n = 9) and atopic dogs (n = 9), respectively; and groups 3 and 4: ≥3-year-old healthy (n = 11) and atopic dogs (n = 14), respectively. METHODS AND MATERIALS: Antibody levels were measured by ELISA. The Canine Atopic Dermatitis Lesion Index (CADLI) was analyzed in relation to antibody levels. RESULTS: Specific IgE and total IgG against M. pachydermatis and S. pseudintermedius were significantly increased in atopic dogs of all ages. Although differences between atopic and healthy dogs, with regard to specific IgG1 and IgG2 levels to each microbe, varied in significance within age groups. No significant relationships were found between the CADLI and any specific immunoglobulin levels for both microbe types. CONCLUSIONS AND CLINICAL IMPORTANCE: In dog skin, microbes may act as allergens triggering inflammatory responses via IgE- and IgG-dependent pathway(s). The affinity of the IgG subclass produced may vary according to antigen type. Specific IgE levels may be related to clinical disease in dogs and not to skin lesion severity.

Residual antibacterial activity of canine hair treated with five mousse products against Staphylococcus pseudintermedius in vitro.

BACKGROUND: Topical therapy alone can be effective in the treatment of canine pyoderma. Topical products are commercially available as shampoos, sprays, wipes and mousses. To date, no studies have evaluated the efficacy of commercially available mousse products in the treatment of canine pyoderma. OBJECTIVE: To determine the residual antibacterial activity of canine hairs treated with mousse products containing different active ingredients. ANIMALS: Fifteen client-owned dogs with no history of dermatological disease. METHODS AND MATERIALS: Dogs were treated once with five mousse products [(i) 2% chlorhexidine and 1% ketoconazole, (ii) 2% chlorhexidine and 2% miconazole, (iii) 3% chlorhexidine and 0.5% climbazole, (iv) 2% salicylic acid 10% ethyl lactate and (v) phytosphingosine HCl 0.05%; control]. Hair samples were collected from each treatment area before application, one hour after application and on days 2, 4, 7, 10 and 14 post-treatment. Collected hairs were weighed and plated on Mueller-Hinton agar plates streaked with a Staphylococcus pseudintermedius isolate showing no antimicrobial resistance. Plates were incubated for 24 h and bacterial growth inhibition zones around the hairs were measured. RESULTS: Mousses 1, 2 and 3 created significant inhibition zones up to Day 10 when compared to pre-treatment samples. On Day 14, only mousse 3 produced a significant zone of inhibition when compared to the pre-treatment sample. Mousses 4 and 5 showed no statistical difference between any of the samples. CONCLUSIONS AND CLINICAL IMPORTANCE: These results suggest that three of the mousse products had residual activity in inhibiting S. pseudintermedius growth in vitro for at least 10 days.

Sodium Hypochlorite/Salicylic Acid Shampoo for Treatment of Canine Staphylococcal Pyoderma.

The emergence of methicillin-resistant Staphylococcus pseudintermedius has increased the interest in topical therapy for treating canine pyoderma. Shampooing with chlorhexidine followed by dilute bleach rinses are often recommended, but household bleach can dry the skin and is unpleasant to use. A shampoo formulated with sodium hypochlorite and salicylic acid was evaluated as sole therapy for dogs with superficial pyoderma associated with S. pseudintermedius, including methicillin-resistant strains. Client-owned dogs were recruited based on positive culture for methicillin-resistant staphylococci or prior failure of pyoderma to respond to antibiotics. This prospective, open-label pilot study assessed the efficacy of the shampoo when used three times weekly for 4 wk. Dogs were evaluated at baseline and at 2 and 4 wk by cytology, clinical examination, and owner assessment. Digital images were also obtained. Baseline bacterial counts, clinical assessments and owner scores were significantly improved at 2 and 4 wk. Clients completing the study reported excellent lathering and dispersion, reduction in odor, and brightening of white and light coats. No owners reported skin dryness or other adverse events during the study. We conclude that this shampoo containing sodium hypochlorite in a vehicle that avoids skin drying is an effective treatment for canine pyoderma.

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.

Low prevalence of mupirocin resistance in Staphylococcus pseudintermedius isolates from canine pyoderma in Korea.

BACKGROUND: Mupirocin is a topical antibacterial drug used for the treatment of staphylococcal infections, including meticillin-resistant Staphylococcus pseudintermedius (MRSP). The recent emergence of resistance to mupirocin is a major concern in many countries. OBJECTIVES: This study investigated the prevalence and genotype of mupirocin-resistant S. pseudintermedius isolated from pet dogs with pyoderma. SAMPLES: A total of 110 clinical isolates of S. pseudintermedius were collected from dogs with pyoderma (n = 110) between July 2010 and September 2016. All animals were client-owned dogs. METHODS: Low- and high-level mupirocin resistance were evaluated with both the broth microdilution and disk diffusion tests. Mupirocin resistance in S. pseudintermedius isolates was confirmed by genetic analysis of the ileS-2 and naïve ileS genes. RESULTS: MRSP and meticillin-susceptible S. pseudintermedius were detected in 69 and 41 dogs, respectively. One MRSP strain was highly resistant to mupirocin and contained the high-level mupirocin resistance gene ileS-2. There were no low-level mupirocin-resistant isolates. CONCLUSION AND CLINICAL IMPORTANCE: Mupirocin is a useful topical antibacterial for MRSP, but a clinical MRSP isolate that had not previously been exposed to mupirocin exhibited the high-level mupirocin resistance in phenotype and genotype. Therefore, continuous monitoring for mupirocin resistance is important in small animal practice.

Use of a Compounded Poloxamer 407 Antibiotic Topical Therapy as Part of the Successful Management of Chronic Ulcerative Dermatitis in a Congo African Grey Parrot ( Psittacus erithacus).

A 23-year-old, 425-g male African grey parrot ( Psittacus erithacus) was evaluated for chronic ulcerative dermatitis of the axillary regions under both wings. Initial swab cultures of the sites had revealed a coagulase-positive methicillin-resistant Staphylococcus aureas (MRSA) with marked antibiotic resistance. A second swab culture obtained 8 weeks after the initial culture showed heavy growth of a coagulase-positive Staphylococcus species, which could not be speciated, but showed the same sensitivity as the previous culture. Previous treatment included systemic antibiotics and a topical antimicrobial cream, with variable response and only temporary resolution. On examination, full-thickness, ulcerative, necrotic dermatitis was present under both wings with intermittent bleeding and subdermal tissue exposure. Initial treatment included wound debridement, oral antibiotics, topical therapy, analgesics, and bandages. After a relapse, a poloxamer gel containing 2% doxycycline, 1% chloramphenicol, and 0.5% mupirocin was used in combination with oral antibiotics and analgesics. On follow-up examination, the skin lesions had completely resolved and the patient was doing well and remains normal 4 years later. This report emphasizes the importance of prompt, aggressive multi-modal therapy for MRSA and other dermal bacterial infections in pet birds that may represent zoonoses or have carrier-state zoonotic potential. Preparation by a compounding pharmacy of a transdermal poloxamer gel containing antibiotics shows promise for severe, infected, ulcerative skin lesions in birds when other therapies fail to achieve a cure.

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.

In vitro bactericidal activity of blue light (465 nm) phototherapy on meticillin-susceptible and meticillin-resistant Staphylococcus pseudintermedius.

BACKGROUND: Staphylococcus pseudintermedius is the most common cause of bacterial skin infections in dogs. Meticillin-resistant infections have become more common and are challenging to treat. Blue light phototherapy may be an option for treating these infections. HYPOTHESIS/OBJECTIVES: The objective of this study was to measure the in vitro bactericidal activity of 465 nm blue light on meticillin-susceptible Staphylococcus pseudintermedius (MSSP) and meticillin-resistant Staphylococcus pseudintermedius (MRSP). We hypothesized that irradiation with blue light would kill MSSP and MRSP in a dose-dependent fashion in vitro as previously reported for meticillin-resistant Staphylococcus aureus (MRSA). METHODS: In six replicate experiments, each strain [MSSP, n = 1; MRSP ST-71 (KM1381) n = 1; and MRSA (BAA-1680) n = 1] were cultivated on semisolid media, irradiated using a 465 nm blue light phototherapeutic device at the cumulative doses of 56.25, 112.5 and 225 J/cm2 and incubated overnight at 35°C. Controls were not irradiated. Colony counts (CC) were performed manually. Descriptive statistics were performed and treatment effects assessed using the Wilcoxon-Mann-Whitney rank-sum test. Bonferroni-corrected rank-sum tests were performed for post hoc analysis when significant differences were identified. RESULTS: There was a significant decrease in CC with blue light irradiation at all doses for MRSA (P = 0.0006) but not for MSSP (P = 0.131) or MRSP (P = 0.589). CONCLUSIONS: Blue light phototherapy significantly reduced CC of MRSA, but not of MSSP or MRSP. The mechanism for the relative photosensitivity of the MRSA isolate is unknown, but is hypothesized to be due to an increased concentration of porphyrin in S. aureus relative to S. pseudintermedius, which would modulate blue light absorption.

Clinical, microscopic and microbial characterization of exfoliative superficial pyoderma-associated epidermal collarettes in dogs.

BACKGROUND: The microscopic and microbial features of the spreading epidermal collarettes of canine exfoliative superficial pyodermas are poorly characterized. OBJECTIVES: To characterize the clinical, cytological, microbial and histopathological features of epidermal collarettes in five dogs. RESULTS: Cytology from the margins of collarettes identified neutrophils, extracellular and intracellular cocci within neutrophils but no acantholytic keratinocytes. Phenotypic and genotypic analyses identified all bacterial isolates from the centre and margin of five epidermal collarettes as Staphylococcus pseudintermedius. PCRs of collarette-associated Staphylococcus strains did not amplify genes encoding for the known exfoliative toxins expA and expB, whereas the predicted siet and speta amplification products were detected in all isolates. Microscopically, epidermal collarettes consisted of interfollicular, epidermal spongiotic pustules. Advancing edges of lesions consisted of peripheral intracorneal clefts in the deep stratum disjunctum above an intact stratum compactum; they contained lytic neutrophil debris, bacterial cocci and fluid, but no acantholytic keratinocytes. This intracorneal location of bacteria was confirmed using Gram stains and fluorescent in situ hybridization with eubacterial- and Staphylococcus-specific probes. The indirect immunofluorescence staining patterns of desmoglein-1, desmocollin-1, claudin-1, E-cadherin and corneodesmosin were discontinuous and patchy in areas of spongiotic pustules, whereas only that of corneodesmosin was weaker and patchy in advancing collarette edges. CONCLUSION: Epidermal collarettes represent unique clinical and histological lesions of exfoliative superficial pyodermas that are distinct from those of impetigo and superficial bacterial folliculitis. The characterization of possible causative staphylococcal exfoliatin proteases and the role of corneodesmosin in collarette pathogenesis deserve further investigation.

Prior antimicrobial use as a risk factor for resistance in selected Staphylococcus pseudintermedius isolates from the skin and ears of dogs.

BACKGROUND: Antimicrobial resistance within bacteria continues to present therapeutic challenges. One presumed risk factor for increased rates of resistance is prior exposure to antimicrobial drugs. OBJECTIVES: To examine the impact of time since most recent exposure, the number of prior antimicrobial exposures and duration of use on antimicrobial resistance rates in Staphylococcus pseudintermedius isolates. METHODS: Inclusion of a case in the study required laboratory isolation of S. pseudintermedius from a clinical specimen. Antibiograms and information regarding prior antimicrobial exposures were extracted from the medical records of dogs diagnosed with pyoderma or otitis externa. RESULTS: Meticillin resistance (MR) was identified in 48.1% of isolates. Recent use of beta-lactam antimicrobials was associated with increased odds of resistance to meticillin (P < 0.001) and fluoroquinolones (P < 0.001). Antimicrobial therapy within 1 month prior to sampling was also associated with MR (60.7%; P = 0.009) and multidrug resistance (61.9%; P = 0.029). The number of prior exposures to beta-lactams or fluoroquinolones were associated with resistance to these same classes (P = 0.001 and 0.02, respectively) and to other antimicrobial classes (P = 0.016 for resistance to fluoroquinolones following treatment with beta-lactams and P = 0.015 for MR following treatment with fluoroquinolones). Longer treatment duration with beta-lactam drugs was associated with higher proportion of MR (P = 0.004). CONCLUSIONS AND CLINICAL IMPORTANCE: Treatment based upon culture and susceptibility testing is highly recommended for dogs that have received multiple antimicrobial drug exposures or that were treated within the preceding month. This may be especially important when the prior therapeutic regimen included a drug from the beta-lactam or fluoroquinolone classes.

Transcription of thymic stromal lymphopoietin via Toll-like receptor 2 in canine keratinocytes: a possible association of Staphylococcus spp. in the deterioration of allergic inflammation in canine atopic dermatitis.

BACKGROUND: Colonization, overgrowth and subsequent infection by Staphylococcus spp. is frequently observed in canine atopic dermatitis (CAD), where it contributes to the intensity of cutaneous inflammation. The mechanisms by which staphylococci contribute to the pathogenesis of CAD are unclear. Studies suggest that thymic stromal lymphopoietin (TSLP), a cytokine induced by a cell wall component of Staphylococcus spp., may play a critical role in Th2 responses including the pathogenesis of CAD. HYPOTHESIS/OBJECTIVE: To determine if synthetic triacylated lipopeptide (TLR1/2 ligand), a cell wall component of Staphylococcus spp., induces the transcription of TSLP via TLR2 in canine keratinocytes. METHODS: Transcription of TSLP was quantified in a canine keratinocyte cell line after stimulation with synthetic triacylated lipopeptide, and again after inhibition of TLR2 by a targeted small interfering RNA. RESULTS: The transcription of TSLP was enhanced 6 h after stimulation with the synthetic triacylated lipopeptide; it was completely suppressed by knockdown of TLR2. CONCLUSIONS AND CLINICAL IMPORTANCE: The results demonstrated that a synthetic cell wall component of Staphylococcus spp. induced transcription of TSLP via TLR2 in canine keratinocytes. Additional studies will be required to investigate whether Staphylococcus spp. contributes to Th2 responses in CAD through TLR2-mediated TSLP production.

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.

Interaction of chlorhexidine with trisEDTA or miconazole in vitro against canine meticillin-resistant and -susceptible Staphylococcus pseudintermedius isolates from two UK regions.

BACKGROUND: Topical therapy is an important alternative to systemic antibacterial therapy for treatment of canine superficial pyoderma in light of the emergence of multidrug-resistant staphylococci. Chlorhexidine is widely used in shampoo products alone or in combination with miconazole or tromethamine-ethylenediaminetetraacetic acid (trisEDTA). Comparisons of these combinations have not been made. HYPOTHESIS/OBJECTIVES: To determine minimum inhibitory concentrations (MICs) of combinations of chlorhexidine/miconazole and chlorhexidine/trisEDTA in vitro in a collection of Staphylococcus pseudintermedius (SP) from northern (NUK) and southeastern (SEUK) United Kingdom (UK) sources. METHODS: MICs of chlorhexidine, miconazole, trisEDTA and combinations of chlorhexidine/miconazole (1:1) or chlorhexidine/trisEDTA (80:16:1 and 80:5:1) were determined for 196 canine SP isolates from NUK [49 meticillin-resistant (MRSP), 50 meticillin-susceptible (MSSP)] and fom SEUK (48 MRSP, 49 MSSP) using agar dilution. RESULTS: TrisEDTA alone did not inhibit growth. Chlorhexidine/miconazole MICs (median = 0.5 mg/L) were lower than those of either drug alone (P < 0.05) and lower than chlorhexidine/trisEDTA MICs (median = 1 mg/L; P < 0.0005) in each bacterial type and from both regions, except for miconazole in NUK MSSP. An additive interaction was noted between chlorhexidine and miconazole or trisEDTA (80:16:1 ratio) in 79 and 43 isolates, respectively, whereas antagonism between chlorhexidine and trisEDTA was noted for three isolates. NUK isolates were more susceptible than SEUK isolates (P < 0.05), except MRSP exposed to chlorhexidine and the chlorhexidine/trisEDTA (80:16:1) combination. CONCLUSIONS AND CLINICAL IMPORTANCE: These low MICs are likely to be exceeded by topical therapy. Evaluation of the mechanisms by which chlorhexidine combinations interact to reduce MICs is warranted, in view of increasing concerns of biocide tolerance in staphylococci.

First report of a mecA-positive multidrug-resistant Staphylococcus pseudintermedius isolated from a dog in New Zealand.

CASE HISTORY: A 14-year-old neutered male Sealyham terrier was referred for assessment of a persistent pyoderma. It had experienced numerous episodes of dermatitis involving pododermatitis, pyoderma and otitis over the previous 6 years. CLINICAL FINDINGS: Superficial, focally deep and mucocutaneous pyoderma were present, with yellow mucoid exudate on both nares and the lower lips crusted with haemopurulent exudate. Epidermal collarettes were present on the dorsal and lateral trunk. There were peri-anal crusts and mild erythema was present on the concave aspect of both pinnae. MICROBIOLOGICAL FINDINGS: Culture and microbiological testing identified Staphylococcus pseudintermedius as the infecting organism. Kirby-Bauer disc susceptibility testing revealed the isolate was resistant to numerous antimicrobials including oxacillin. PCR testing of the isolate identified the presence of the mecA gene which confers resistance to ß-lactam antimicrobials. Pulsed field gel electrophoresis typing suggested the isolate was not related to the methicillin-resistant S. pseudintermedius that had been reported to be associated with canine infections in Western Australia. DIAGNOSIS: Superficial, deep and mucus membrane pyoderma associated with a multi-drug resistant S. pseudintermedius. CLINICAL RELEVANCE: This is the first recorded case of canine pyoderma involving methicillin-resistant multidrug-resistant S. pseudintermedius in New Zealand. Treatment of such cases is difficult because the number of effective and available antimicrobials is limited. This finding should raise the awareness of the veterinary and medical professions to the presence of such organisms in New Zealand and stimulate a discussion about possible biosecurity barriers, treatment strategies and prevention of zoonotic and nosocomial infections.

Characterization of Staphylococcus pseudintermedius isolated from diseased dogs in Lithuania.

The aim of this study was to characterize Staphylococcus pseudintermedius for its antimicrobial resistance and virulence factors with a special focus on methicillin-resistant (MRSP) strains isolated from sick dogs in Lithuania. Clinically sick adult dogs suffering from infections (n=214) and bitches with reproductive disorders (n=36) from kennels were selected for the study. Samples (n=192) from the 250 tested (76.8%) dogs were positive for Staphylococcus spp. Molecular profiling using the species-specific nuc gene identified 51 isolates as S. pseudintermedius (26.6% from a total number of isolated staphylococci) of which 15 isolates were identified as MRSP. Ten MRSP isolates were isolated from bitches with reproductive disorders from two large breeding kennels. Data on susceptibility of S. pseudintermedius to different antimicrobials revealed that all isolates were susceptible to vancomycin, daptomycin and linezolid. Two isolates (3.9%) were resistant to rifampicin. A high resistance was seen towards penicillin G (94.1%), tetracycline (64.7%) and macrolides (68.7%). Resistance to fluoroquinolones ranged from 25.5% (gatifloxacin) to 31.4% (ciprofloxacin). The most prevalent genes encoding resistance included blaZ, aac(6')-Ie-aph(2'')-Ia, mecA, and tet(M). The Luk-I gene encoding a leukotoxin was detected in 29% of the isolates, whereas the siet gene encoding exfoliative toxin was detected in 69% of the S. pseudintermedius isolates. This report of MRSP in companion animals represents a major challenge for veterinarians in terms of antibiotic therapy and is a concern for both animal and public health.

Dorsal black skin necrosis in a Vietnamese pot-bellied pig.

BACKGROUND: Thermal burns are an uncommon cause of injury in large animals. CASE REPORT: A 10-month-old pet female black and white Vietnamese pot-bellied pig presented to the emergency service with fever and erythematous to purpuric skin lesions affecting the intermandibular space and hocks. One week prior to the emergency visit, she had appeared restless and in pain. Two weeks following the emergency visit, she again presented to the large animal clinic with sloughing of the pigmented skin on her head, face, dorsal and lateral trunk sparing the nonpigmented skin and pigmented ears. The affected skin constituted ~40% of her total skin. Histopathological findings for affected skin included full-thickness epidermal and partial to full-thickness dermal coagulative necrosis with follicular epithelial mineralization, while that from normal-appearing pigmented skin was within normal limits. A culture from a skin biopsy yielded meticillin-resistant Staphylococcus aureus (ST-72). Treatments included oral antibiotics, pain management, hyperbaric oxygen therapy and general anaesthesia to facilitate debridement. Healthy skin was often present when the necrotic skin was debrided, although in some areas the necrosis extended into the underlying fat. Complications that occurred during rehabilitation included intense pruritus that resulted in self-trauma and the formation of a nasal fistula, which was later surgically corrected. CONCLUSIONS AND CLINICAL IMPORTANCE: Cases of dorsal thermal necrosis in pot-bellied pigs are uncommon in the literature. Based on the clinical presentation and lack of another identifying cause, the lesions were attributed to a sun-induced thermal burn.