Evaluation of methicillin resistance in Staphylococcus intermedius isolated from dogs

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

OBJECTIVE

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

PROCEDURES

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

RESULTS

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

CONCLUSIONS

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

A review of topical therapy for skin infections with bacteria and yeast

BACKGROUND

Cutaneous infections with bacteria and yeasts are common in small animal practice. Treatment with systemic antibiotics or antifungal agents may not be ideal, because of the increasing development of multiresistant organisms, the cost and the possible adverse effects. Topical antimicrobials may be used as adjunctive therapy to systemic treatment or as sole therapy instead of systemic treatment.

OBJECTIVE

This literature review evaluated studies on topical antimicrobial treatment of skin infections.

METHODS

In vitro and in vivo studies evaluating topical antimicrobial agents were identified using a number of electronic and manual searches of textbooks and articles. Studies were evaluated, and the evidence for or against the use of the topical agents was extracted.

RESULTS

There is good evidence for the efficacy of chlorhexidine and, to a lesser degree, benzoyl peroxide in canine bacterial skin infections. There is limited evidence for the efficacy of silver sulfadiazine and medical honey against bacterial skin infections in the dog, and for the efficacy of hydrogen peroxide and stannous fluoride in the horse. Good evidence supports the use of a combination of chlorhexidine and miconazole in dogs with cutaneous Malassezia infections. There is insufficient evidence to recommend any other topical therapy for use in cutaneous infections.

CONCLUSIONS AND CLINICAL IMPORTANCE

Although many antimicrobial topicals are marketed in veterinary dermatology, the efficacy has been reported for only a minority of agents. Randomized controlled trials evaluating various topical treatments are therefore urgently needed.