Genotypic relatedness of staphylococcal strains isolated from pustules and carriage sites in dogs with superficial bacterial folliculitis

OBJECTIVE

To determine whether staphylococcal isolates cultured from pustules and carriage sites in dogs with superficial bacterial folliculitis were genotypically the same strain by use of pulsed-field gel electrophoresis (PFGE).

ANIMALS

40 dogs with superficial bacterial folliculitis.

PROCEDURES

Samples were obtained from 3 pustules and 3 carriage sites (anus, axillary skin, and nasal mucosa). Bacterial culture, morphologic identification, Gram staining, catalase and coagulase tests, speciation, and PFGE were performed.

RESULTS

Of 246 isolates, 203 were Staphylococcus intermedius, 5 were Staphylococcus aureus, 15 were Staphylococcusspp, and 22 were coagulase-negative staphylococcal isolates. No dog had an isolate with the same PFGE pattern as an isolate from another dog. Coagulase-positive isolates from multiple pustules and multiple carriage sites had the same PFGE pattern in 37 of 39 (94.9%) and 22 of 39 (56.4%) dogs, respectively. Coagulase-positive staphylococcal isolates from at least 1 pustule had the same PFGE pattern as an isolate from at least 1 carriage site in 34 of 36 (94.4%) dogs. Ninety-seven of 116 (83.6%) coagulase-positive staphylococcal isolates from pustules had the same PFGE pattern as an isolate from at least 1 carriage site. Sixty-nine of 91 (75.8%) coagulase-positive staphylococcal isolates from carriage sites had the same PFGE pattern as an isolate from at least 1 pustule.

CONCLUSIONS AND CLINICAL RELEVANCE

Coagulasepositive staphylococcal strains were heterogeneous among dogs with superficial bacterial folliculitis. In individual dogs, strains from multiple pustules were genotypically the same, and strains from pustules were genotypically the same as strains from carriage sites.

Prospective study of bacterial overgrowth syndrome in eight dogs

Eight dogs with cutaneous lesions, clinical signs and cytological findings compatible with bacterial overgrowth syndrome were compared with four healthy dogs. The affected dogs were treated for 28 days with 30 mg/kg/day cephalexin. The results showed that the syndrome was a superficial cutaneous disorder characterised by marked pruritus, greasy seborrhoea, offensive odour, erythema, lichenification, hyperpigmentation, excoriations and alopecia involving principally the ventral aspect of the body, but no papules, pustules, epidermal collarettes or crusts; it was caused by overgrowths of Staphylococcus intermedius all over the body surface. Histopathological findings included a superficial, perivascular, hyperplastic and spongiotic dermatitis with a mixed inflammatory infiltrate, but no lesions suggestive of a true pyoderma. In the affected dogs, anti-staphylococcal immunoglobulin G levels were high, but anti-staphylococcal immunoglobulin E levels were low, suggesting that staphylococcal hypersensitivity is not the underlying pathogenic process. The antibiotic treatment improved the condition of all the dogs, but five of the eight had an underlying allergic skin disease.

Adherence of Staphylococcus intermedius to corneocytes of healthy and atopic dogs: effect of pyoderma, pruritus score, treatment and gender

Staphylococcal pyoderma occurs commonly in atopic dogs. Some studies have suggested that adherence of staphylococci to corneocytes of atopic dogs and humans is higher than to corneocytes of healthy individuals. This hypothesis and possible differences resulting from the presence or absence of pyoderma, the severity of pruritus or the effect of treatment or gender, were studied. Adherent bacteria (Staphylococcus intermedius) were quantified by computerized image analysis on corneocytes collected from healthy or atopic dogs using double-sided adhesive tape. The adherence of S. intermedius to the corneocytes of atopic dogs was significantly greater than to those of healthy dogs (P=0.005). Furthermore, adherence was significantly greater in dogs with high levels of pruritus compared to those with low scores. No significant differences were found between atopic dogs with no history of pyoderma, atopic dogs with a history of pyoderma and atopic dogs with pyoderma at the time of sampling (P=0.068), suggesting that factors other than adherence are necessary for clinical pyoderma to develop. Treatment did not generally influence the adherence of S. intermedius to corneocytes of atopic dogs and there was no gender difference in adherence in either healthy or atopic dogs.

Isolation of Staphylococcus schleiferi from healthy dogs and dogs with otitis, pyoderma, or both

OBJECTIVE

To determine the frequency of isolation and susceptibility patterns of Staphylococcus schleiferi from healthy dogs and dogs with otitis, pyoderma, or both that had or had not received antimicrobial treatment.

DESIGN

Prospective study.

ANIMALS

50 dogs.

PROCEDURE

Dogs were allocated to 1 of 4 groups: healthy dogs (n=13), dogs without otitis but with pyoderma (10), dogs with otitis but without pyoderma (11), and dogs with otitis and pyoderma (16). Bacteriologic culture of ear swab specimens was performed in all dogs. Bacteriologic culture of skin swab specimens was also performed in dogs with concurrent pyoderma. Isolates were identified as S schleiferi subsp schleiferi or S schleiferi subsp coagulans on the basis of growth and biochemical characteristics.

RESULTS

S schleiferi was not isolated from any dogs with pyoderma only. Staphylococcus schleiferi subsp schleiferi was isolated from the ears of 2 healthy dogs, and the skin and ears of 2 dogs and the skin of 1 dog with otitis and pyoderma. Staphylococcus schleiferi subsp coagulans was isolated from the ears of 3 dogs with otitis only, and the ears of 6 dogs and the skin of 2 dogs with otitis and pyoderma. One of the S schleiferi subsp schleiferi isolates from ears, 2 of the S schleiferi subsp coagulans isolates from ears, and 1 of the S schleiferi subsp coagulans isolates from the skin were resistant to methicillin. One methicillin-resistant isolate from the ears and 1 from the skin were also resistant to fluoroquinolones.

CONCLUSIONS AND CLINICAL RELEVANCE

S schleiferi subsp schleiferi was detected in healthy dogs and dogs with otitis and pyoderma. Methicillin-resistant and -susceptible S schleiferi subsp schleiferi and S schleiferi subsp coagulans were detected as the predominant organisms in dogs with otitis.

Species specificity in the adherence of staphylococci to canine and human corneocytes: a preliminary study

Staphylococcal pyoderma is rarely contagious between dogs and humans, or humans and dogs. This study investigated the hypothesis that there are species differences in adherence of Staphylococcus intermedius (the most common isolate from dogs) and Staphylococcus aureus (the most common isolate from humans) to canine and human corneocytes. Sheets of corneocytes were collected from the ventral abdomen of 10 dogs and the medial forearm of 10 humans (all healthy and without any history or physical signs of skin disease) using double-sided tape. Staphylococcus intermedius from a case of canine bacterial pyoderma and a human strain of S. aureus were prepared in phosphate buffered saline (PBS) and applied in duplicate, respectively, to the canine and human corneocyte-covered tapes using PBS as negative control. After incubation, rinsing, and staining with crystal violet, quantification of the adherent bacteria was carried out blindly by computerized image analysis. Staphylococcus intermedius was found to adhere significantly more to canine corneocytes than S. aureus (P = 0.0006), whereas S. aureus showed greater adherence to human corneocytes than S. intermedius (P < 0.0001). In addition, the pattern of adherence differed between the two organisms, with S. intermedius adhering to the entire surface and S. aureus adhering mainly to the periphery of both canine and human corneocytes. Preference for adherence to these two hosts may explain, in part, why S. intermedius and S. aureus are uncommonly isolated from human and canine skin infections, respectively.

Fluorescent amplified fragment length polymorphism genotyping of human and animal Staphylococcus aureus isolates from dairy farms with manual milking

Fluorescence amplified fragment length polymorphism (fAFLP) was used to assess the genetic relatedness of 40 Staphylococcus aureus strains isolated from human and animal skin samples in seven dairy farms with manual milking. S. aureus was isolated from 11 out of 30 (36%) human skin samples and from 29 out of 100 (29%) teat skin samples from apparently healthy cows. Genomic DNA from each isolate was double-digested with EcoRI and MseI and complementary oligonucleotide adaptors were ligated to the restriction fragments. Pre-selective and selective amplification reactions were performed, the amplified fragments were separated by electrophoresis in an ABI377 sequencer and analysed using GeneScan 3.1 and Genotyper 2.5. Three single isolates (a-c), a predominant cluster with 35 isolates (d) and another cluster with two isolates (e) were identified. Both clusters d and e included human and animal isolates genetically related, because the profiles had 90-100% homology. Since no cluster was comprised uniquely of human or animal isolates and given the close genetic relatedness among human and animal samples in the farms, the present findings support the hypothesis that dairy workers can spread S. aureus through manual milking.

Leucocytoclastic vasculitis associated with Staphylococcus intermedius in the pastern of a horse

A pregnant quarterhorse mare became acutely lame as a result of severe swelling of its right hind leg, thought to have been caused by a fracture or a muscle tear. Diagnostic procedures ruled out a traumatic musculoskeletal cause and a physical examination revealed chronic pastern dermatitis ('scratches'/'grease heel'). Histopathological evaluation of biopsy samples from the right hind leg was consistent with a leucocytoclastic vasculitis, and culture yielded Staphylococcus intermedius. The treatment and infectious causes of pastern dermatitis are discussed.

Antimicrobial drug susceptibility of Staphylococcus intermedius clinical isolates from canine pyoderma

A total of 50 Staphylococcus intermedius strains isolated in France from canine pyodermas in 2002 were investigated for their susceptibility to various antimicrobial drugs. Antimicrobial susceptibility was assessed using a 2-fold serial dilution method in Mueller-Hinton agar, and the minimal inhibitory concentrations (MICs) were determined. About 62% of the 50 strains tested were producers of beta-lactamase and categorized as penicillin-resistant. About 26% demonstrated resistance to sulphonamides, 46% to oxytetracycline, 30% to chloramphenicol, 28% to streptomycin, kanamycin, neomycin or erythromycin, 22% to clindamycin, 6% to doxycycline, 2% to gentamicin, enrofloxacin, marbofloxacin or pradofloxacin. Acquired resistance was not observed to a clavulanic acid-amoxicillin combination, oxacillin, cephalosporins (cephalexin, ceftiofur and cefquinome), trimethoprim, a sulphamethoxazole-trimethoprim combination and florfenicol. About 42% were simultaneously resistant to three or more antimicrobial classes (multiresistance). All isolates with acquired resistance to erythromycin were also resistant to streptomycin and neomycin/kanamycin. About 22% of isolates exhibited cross-resistance between erythromycin and clindamycin and all clindamycin-resistant isolates also exhibited resistance to erythromycin. Resistance to penicillin, oxytetracycline and chloramphenicol was also positively associated with resistance to erythromycin and streptomycin.

Molecular characterization of Staphylococcus intermedius carriage by healthy dogs and comparison of antimicrobial susceptibility patterns to isolates from dogs with pyoderma

We conducted an epidemiological study of Staphylococcus intermedius using arbitrarily primed PCR (AP-PCR) and antibiograms. One hundred and twenty-five S. intermedius isolates were recovered from the oral cavity and/or cranial hair coat of healthy dogs enrolled in a pet therapy program. Commensal S. intermedius was cultured from 32% of the oral cavity cultures and 13% of the cranial hair coat cultures. We characterized the colonization of the dogs as transient, intermittent, or persistent. For dogs characterized as persistently colonized, 73% of the isolates came from the oral cavity. These isolates were also genotyped by AP-PCR. A single major AP-PCR type was observed in 91% of the dogs (n=22); minor variations were frequently observed in these major types. Antibiograms of these commensal isolates were compared to antibiograms from 97 historical clinical isolates (1988-1992) obtained from cases of canine pyoderma. Resistance was most often observed to penicillin (64% and 55%) and tetracycline (38% and 38%) among the commensal and clinical isolates, respectively. The commensal isolates were significantly less resistant to erythromycin, clarithromycin, clindamycin, and trimethoprim/sulfamethoxazole. Our data suggests that differences in both genotype and antimicrobial susceptibility phenotypes exist among S. intermedius strains isolated from different anatomic sites from the same dog and supports the opportunistic nature of S. intermedius in canine infections.

Isolation and characterization of staphylococci from external auditory meatus of dogs with or without otitis externa with special reference to Staphylococcus schleiferi subsp. coagulans isolates

Staphylococci were isolated from the external auditory meatus in 14 (48.3%) of 29 dogs affected with otitis externa (OE dogs) and 28 (68.3%) of 41 dogs without OE (non-OE dogs). Twenty-two OE isolates were identified as belonging to 12 species, and 42 non-OE isolates were identified as belonging to 13 species. The predominant species found in both OE and non-OE isolates were S. intermedius, and S. epidermidis. Thirty-eight (59.4%) of 64 isolates were resistant to one or more of the 17 antimicrobial agents tested. Resistance to PCG and ABPC was most frequent. S. schleiferi subsp. coagulans, a recent etiologic agent of canine OE, was isolated from OE and non-OE dogs. All of the 5 S. schleiferi subsp. coagulans isolates showed typical characteristics. No clear difference in the extracellular enzyme or toxin profiles, nor in the PFGE patterns, was demonstrated between the OE and non-OE isolates of S. schleiferi subsp. coagulans. A new PCR primer set specific for 16S rDNA was designed to identify strains of S. schleiferi subsp. coagulans. The amplified fragment was detected in all of the 5 isolates as well as the type strain GA 211 (=JCM 7470) and a reference strain GA 11, but was not detected in any strains of the related species, S. aureus, S. intermedius and S. hyicus. The PCR may allow a simple, rapid and precise identification of S. schleiferi subsp. coagulans, in addition to the standard tube test for free coagulase.

Evaluation of aerobic bacteriologic culture of epidermal collarette specimens in dogs with superficial pyoderma

OBJECTIVE

To evaluate a method of aerobic bacteriologic culture of epidermal collarette specimens from dogs with superficial pyoderma and compare results with those for aerobic bacteriologic culture of abdominal skin specimens in healthy dogs.

DESIGN

Prospective study.

ANIMALS

22 dogs with epidermal collarettes and 24 healthy dogs.

PROCEDURE

Dry sterile cotton swabs were rolled across epidermal collarettes or hairless areas of abdominal skin in healthy dogs and submitted for aerobic bacteriologic culture. Hemolytic colonies of gram-positive-staining cocci were tested for catalase production, and if results were positive, a coagulase test was performed. Colonies with coagulase activity were tested for the ability to ferment mannitol. Antimicrobial susceptibility testing was performed on all Staphylococcus spp that were isolated.

RESULTS

S. intermedius was isolated from collarettes in 18 of 22 dogs with superficial pyoderma but not from healthy dogs. Estimated sensitivity and specificity of the culture method were 81.8% and 100%, respectively. There were no significant differences in the ability to culture S. intermedius, the number of S. intermedius isolates without resistance to antimicrobials, and the number of S. intermedius isolates resistant to penicillin G when comparing dogs with superficial pyoderma for the first time and dogs with recurrent pyoderma, dogs that did or did not receive concurrent antimicrobials, and dogs with and without underlying allergic disease.

CONCLUSIONS AND CLINICAL RELEVANCE

Bacteriologic culture of epidermal collarette specimens was a simple and reliable method for identification of S. intermedius in dogs with superficial pyoderma, regardless of history of pyoderma or current antimicrobial use.

A real-time PCR assay to detect the Panton Valentine Leukocidin toxin in staphylococci: screening Staphylococcus schleiferi subspecies coagulans strains from companion animals

Recent reports suggest that methicillin-resistant strains of Staphylococcus schleiferi subspecies coagulans are now commonly isolated from dogs. Given the association of a potentially mobile SCCmec type IV element with lysogenic phage-encoded Panton Valentine Leukocidin (PVL) toxin genes in community-acquired methicillin-resistant Staphylococcus aureus strains we hypothesized that methicillin-resistant S. schleiferi ssp. coagulans strains may also encode PVL toxin genes. Forty S. schleiferi ssp. coagulans strains isolated from companion animals were studied. Susceptibility to oxacillin was determined by broth microdilution and all isolates were screened by PCR for the presence of the mecA gene. SCCmec typing was performed on 14 isolates. A real-time PCR assay was developed for the detection of the PVL genes using a SmartCycler. Pulsed-field gel electrophoresis (PFGE) was performed to determine whether S. schleiferi ssp. coagulans strains were homogeneous. Twenty-eight of the 40 isolates (70%) were resistant to oxacillin and 26/28 possessed the mecA gene by PCR. SCCmec IV was identified in seven strains; the other seven isolates were not typable by this technique. All 40 strains were negative for the PVL toxin gene. PFGE showed a heterogeneous population and 13 different profiles were determined. In conclusion, this study showed that PVL toxin genes were not detected in a heterogeneous population of methicillin-resistant S. schleiferi ssp. coagulans strains isolated from companion animals.

A prospective study of the clinical findings, treatment and histopathology of 44 cases of pyotraumatic dermatitis

Pyotraumatic dermatitis (hot spot) is a common clinical syndrome in dogs but there are few prospective scientific studies related to it. The aim of this study was to investigate correlations among clinical pyotraumatic dermatitis, histopathology of the lesions and possible predisposing causes. The relationship of these with breed, age, sex and location of lesion was assessed statistically. A clinical diagnosis of acute pyotraumatic dermatitis was made in 44 privately owned dogs. Males exceeded females (P = 0.0348) and lesions were more common in dogs aged 4 years or less (P < 0.0001). Lesions were most often seen on the cheek, neck and lateral thigh with a significant correlation between breed and site of lesion (P < 0.0001). In 31 cases a possible underlying cause was found or suspected. In contrast to previous studies, no otitis externa was recorded and the study was conducted in an area without endemic fleas. Fourteen breeds were represented of which Rottweiler, German shepherd dog and golden retriever were most common. There was no significant seasonal incidence and no correlation among site of lesion and cause, time of year, age or sex. Histopathologically, the dogs could be separated into four patterns by the presence or absence of eosinophils and/or folliculitis. Eosinophils have not previously been recorded in pyotraumatic dermatitis but were seen in 29 cases. Acute folliculitis was seen in 20 cases. However, no correlation was seen among age, sex, breed, underlying cause or site of lesion and histopathology. Twenty-seven cases were cultured for bacteria of which 25 grew Staphylococcus intermedius and two were negative.

Characteristics of Staphylococcus intermedius Isolates from Diseased and Healthy Dogs

Staphylococcus intermedius isolates from diseased and healthy dogs were examined for production of extracellular enzymes and toxins, and phage patterns. There were no significant differences between the two groups of isolates in the production rates of DNase, protease, lipase, gelatinase, hyaluronidase, hemolysins, protein A, and TSST-1, or in phage patterns. But the production rate of enterotoxins in isolates from diseased dogs was significantly higher than that in isolates from healthy dogs. PFGE analysis was performed with isolates from different body sites in individual dogs. In 3 of 6 healthy dogs, identical PFGE patterns were seen in isolates from the nares, external auditory meatus or skin. The remaining 3 dogs yielded isolates of different patterns. In 4 of 6 diseased dogs, identical patterns were seen in isolates from lesions as well as from the other normal sites.

In vitro antimicrobial activity of orbifloxacin against Staphylococcus intermedius isolates from canine skin and ear infections

The objective of the study was to evaluate the in vitro activity of orbifloxacin against Staphylococcus intermedius strains isolated in France from canine skin and ear infections. The minimum inhibitory concentrations (MICs) of orbifloxacin against 240 field S. intermedius isolates (69 skin and 171 ear isolates) ranged from 0.016 to 8 mg l(-1), with MIC50 and MIC90 equal to 0.5 and 1 mg l(-1), respectively. Only one strain, a pyoderma isolate was resistant (MIC=8 mg l(-1)). Orbifloxacin was tested at different concentrations for killing rate against five isolates obtained from pyoderma cases and against a reference strain (Staphylococcus aureus ATCC 29213). Orbifloxacin expressed a concentration-dependent bactericidal activity against the S. aureus reference strain, but a time-dependent bactericidal activity against S. intermedius. Orbifloxacin induced bactericidal effect against the S. intermedius strains tested with concentrations equal to or two times MIC.

Transmission of multiple antimicrobial-resistant Staphylococcus intermedius between dogs affected by deep pyoderma and their owners

The occurrence of antimicrobial-resistant Staphylococcus intermedius strains was investigated in 13 dogs affected by deep pyoderma, their owners and 13 individuals without daily contact with dogs (control group). A total of 90 canine and 33 human S. intermedius isolates were typed by pulsed field gel electrophoresis (PFGE) to determine their possible identity. The occurrence of S. intermedius in dog-owners was significantly higher compared with the control group (Fisher's exact test, P=0.03), with S. intermedius being detected in seven dog-owners and in one individual not exposed to dogs. The results of the PFGE analysis showed that six out of 13 (46%) owners carried strains identical to those isolated from their dogs. Strains detected in both dogs and humans were resistant up to five different antimicrobial classes, including penicillins, fusidic acid, macrolides/lincosamides, tetracycline and chloramphenicol. Based on the results of this study, owners of dogs affected by deep pyoderma often carry multiple antimicrobial-resistant strains of S. intermedius occurring in their dogs. Independent of the direction and modalities of transmission, this finding raises questions concerning the possible transfer of resistance genes from canine S. intermedius to human pathogenic staphylococci.

Cloning and sequence analysis of genes encoding Staphylococcus hyicus exfoliative toxin types A, B, C, and D

Exfoliative toxins produced by certain strains of Staphylococcus hyicus mediate exudative epidermitis in pigs. In this study the genes coding for four different exfoliative toxin from S. hyicus (ExhA, ExhB, ExhC, and ExhD) were cloned and sequenced. The coding sequence of the four toxin genes ranged from 816 to 834 bp. The amino acid sequences of these four toxins were homologous to the earlier described exfoliative toxins SHETB from S. hyicus and ETA, ETB, and ETD from Staphylococcus aureus. The homology between the S. hyicus toxins was at the same level as the homology to the exfoliative toxins from S. aureus. The toxins showed similarity to serine proteases, including preservation of the catalytic tract in ExhA, ExhB, and ExhC. However, in ExhD, Asp in the putative catalytic tract was replaced with Glu. The recombinant toxins could be expressed in Escherichia coli, and three of the four toxins were recognized by monoclonal antibodies raised against native exfoliative toxins.

Human recombinant interferonalpha-2b for management of idiopathic recurrent superficial pyoderma in dogs: a pilot study

The oral use of human recombinant interferonalpha-2b at 1,000 IU/ml/day appeared to provide only a transient benefit as compared with placebo for management of idiopathic recurrent superficial pyoderma in dogs. Further investigation using a larger population of dogs is needed to determine whether interferon is effective for long-term treatment of this condition.

The porcine skin associated T-cell homing chemokine CCL27: molecular cloning and mRNA expression in piglets infected experimentally with Staphylococcus hyicus

CCL27 (also named CTACK, ALP, ILC and ESkine) is a CC chemokine primarily expressed by keratinocytes of the skin. The cognate receptor of CCL27 named CCR10 (GPR-2), is also expressed in skin-derived cells, and in addition by a subset of peripheral blood T-cells and in a variety of other tissues. In this paper, we report the cloning of porcine CCL27 cDNA and investigation of CCL27 mRNA expression in Staphylococcus hyicus infected piglets. At the protein level, 77 and 74% homology was found to human and mouse CCL27 sequences, respectively. The results of the expression analyses show that CCL27 mRNA is upregulated in the skin of infected piglets and to a lesser extent in piglets recovered from disease and without clinical signs of infection, indicating a role for CCL27 both during inflammation and after recovery from an infection.

Isolation of exfoliative toxin from Staphylococcus intermedius and its local toxicity in dogs

A rounding effect was demonstrated in cultured cells inoculated with the culture filtrates (CFs) of 60 strains of Staphylococcus intermedius derived from dogs affected with pyoderma. Exfoliative toxin (ET)-like toxin (ETLT) was isolated from the CF of S. intermedius strain D-52, which exhibited strong rounding activity and then was purified by gel filtration on a Sephadex G-75 column, and by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The ETLT caused exfoliation in 1-day-old chickens, suckling Syrian hamsters, and dogs, but not in suckling mice. The ETLT was serologically different from exfoliative toxin A (ETA), exfoliative toxin B (ETB), exfoliative toxin C (ETC), S. hyicus exfoliative toxin A (SHETA), and SHETB, as shown by Western blot analysis. The molecular weight of the ETLT was estimated at 30 kDa by SDS-PAGE. In the present study, we propose the ETLT was a novel type of ET, S. intermedius exfoliative toxin (SIET).

Isolation of Staphylococcus schleiferi from dogs with pyoderma

OBJECTIVE

To determine frequency with which Staphylococcus schleiferi could be isolated from dogs with pyoderma and antimicrobial susceptibility patterns of isolates that were obtained.

DESIGN

Prospective study.

ANIMALS

54 dogs with a first (n = 14) or recurrent (40) episode of pyoderma.

PROCEDURE

Specimens were obtained and submitted for bacterial culture. Isolates were identified as S schleiferi on the basis of growth and biochemical characteristics. Two isolates were submitted for DNA sequencing to confirm identification. Methicillin susceptibility was determined by means of disk diffusion with oxacillin-impregnated disks.

RESULTS

3 of 14 dogs examined because of a first episode of pyoderma and 12 of 40 dogs examined because of a recurrent episode of pyoderma were receiving antimicrobials at the time of specimen collection. Staphylococcus schleiferi was not isolated from any dog with first-time pyoderma but was isolated from 5 dogs with recurrent pyoderma that were not receiving antimicrobials at the time of specimen collection and 10 dogs with recurrent pyoderma that were receiving antimicrobials. Nine isolates were identified as S schleiferi subsp schleiferi, and 6 were identified as S schleiferi subsp coagulans. All S schleiferi subsp schleiferi isolates were resistant to methicillin, but only 2 S schleiferi subsp coagulans isolates were. Two methicillin-resistant isolates were also resistant to fluoroquinolones, and 1 isolate had intermediate susceptibility to fluoroquinolones.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that S schleiferi subsp schleiferi and S schleiferi subsp coagulans may be isolated from dogs with recurrent pyoderma. Although isolates from dogs with pyoderma were frequently resistant to methicillin, multiple drug resistance was uncommon.

Frequency of superantigen-producing Staphylococcus intermedius isolates from canine pyoderma and proliferation-inducing potential of superantigens in dogs

This preliminary study investigated the potential role of staphylococcal superantigens in the pathogenesis of canine pyoderma. The staphylococcal enterotoxins A (SEA), SEB, SEC and SED, and the toxic shock syndrome toxin-1 (TSST-1) were assayed in isolates from skins of dogs with pyoderma. Culture supernatants from 25 of 96 isolates were positive for multiple superantigens, with SEA and SEC being the most frequently detected. In in vitro stimulation of canine peripheral blood mononuclear cells and quantitative flow cytometry revealed that low concentrations of SEA and SEB were potent stimulators of blastogenesis of T cells.