Veterinary Medicine - October 2008 - (Page P8)

Using once-daily products, such as cefpodoxime, may enhance compliance with the treatment regimen and unburden the pet owner. Recently available is a long-acting injectable cephalosporin, cefovecin. Each single subcutaneous injection of this aqueous product is equivalent to a two-week course of an orally administered cephalo sporin in the treatment of superﬁcial staphylococcal pyoderma. Increasingly, staphylococcal skin infections may require a culture and sensitivity test prior to treatment. The rule of thumb for when to culture includes resistance, response, and recurrence. A few years ago, culture and susceptibility tests were rarely necessary before treating staphylococcal skin infections—their susceptibility patterns were predictable, as nearly 100% of isolates were susceptible to a cephalosporin. This situation has now changed. Emergence of resistant strains dictates that any animal with apparent resistance to treatment or inadequate response to treatment must be cultured. Likewise, a recurrent infection should always be cultured, especially if the animal has been treated frequently in the past with various antibiotics. The goal is not only to choose the correct antibiotic, but also to identify the presence of methicillin-resistant strains. If the laboratory reports a coagulase-positive Staphylococcus that is methicillin-resistant, order a staphylococcal speciation test. This test identiﬁes the particular strain of Staphylococcus present and if it is a human or animal strain. This information will allow you to take necessary isolation precautions and to advise the client about any zoonotic concern. Adjunct treatment with topical antimicrobials or immunomodulatory products is becoming more important, particularly for recurrent infections. To every veterinarian’s frustration, the underlying reason for recurrent infections sometimes defies diagnosis— the infections respond completely to antibiotic treatment yet continue to recur soon after such treatment is discontinued. Topical therapy (e.g., antimicrobial shampoos, conditioners, or sprays) is especially recommended in cases of recurrent infection to more quickly eradicate the organism from the hair coat and potentially prevent recolonization. Injectable staphylococcal bacterins will also prevent recurrence in some cases. Educate yourself and your clients about procedures for—and potential hazards of—methicillinresistant staphylococcal infections. News stories on the emergence of superbugs appear in the popular press with increasing frequency, sometimes with an alarming tone. We now know that most staphylococcal infections on animals occur with the coagulase-positive species Staphylococcus intermedius (now known as Staphylococcus pseudintermedius), and Staphylococcus schleiferi. These species prefer to colonize animals and are not transmitted to people under usual circumstances. On the other hand, Staphylococcus aureus prefers to colonize people. Only about 1% of canine staphylococcal skin infections can be attributed to S. aureus and only about one third of those are methicillin-resistant. Any staphylococcal species can become methicillinresistant. Methicillin, a laboratory reagent, has been used to test staphylococci for antibiotic resistance. A strain of methicillin-resistant Staphylococcus (MRS) will be completely resistant to treatment with all penicillin and cephalosporin drugs. In some cases, MRS will be susceptible to other routine antibiotics, such as potentiated sulfas or ﬂuoroquinolones; in other cases, MRS can be highly resistant to nearly all antibiotics, except perhaps chloramphenicol and other esoteric and very expensive human drugs. What’s the implication? The landscape of staphylococcal infections is changing. New drugs make client compliance more practical. Studies are underway to determine how often patients, owners, and veterinarians are carriers of resistant strains and to determine the signiﬁcance of such carriage. It seems clear that future cases will increasingly call for judicious use of antibiotics and the use of non-antibiotic alternatives when possible. We must redouble our efforts to use these important drugs wisely. 8 PRACTICAL DERMATOLOGY FOR THE BUSY PRACTITIONER

Table of Contents Feed for the Digital Edition of Veterinary Medicine - October 2008

Veterinary Medicine - October 2008 Contents Leading Off Clinical Exposures Idea Exchange Stalking Stones Vaginitis in Dogs CE Form Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - October 2008

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