8/9/2019 Manejo de Infecciones Recurrentes de La Piel Marsella

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MANAGEMENT OF RECURRENT SKIN INFECTIONS

Rosanna Marsella, DVM, DACVDCollege of Veterinary MedicineUniversity of Florida, Gainesville, FL, USA

Recurrent skin infections have always been a source of frustration in generalpractice but now, besides the normal frustration, we are also experiencing asteep increase of antibiotic resistance which is adding challenge to themanagement of these cases. The resistance could be due to a variety of reasonsincluding widespread and not always appropriately done antibiotic use. For thisreason, is very important to use antibiotics well, using the right dose, for the rightamount of time, at the right dosing interval. Shorter courses of antibioticscombined with suboptimal doses allow bacteria to build resistance.

Some antibiotics are also more prone to induce resistance and others and in

some cases they can induce resistance to antibiotics that had never been usedbefore. For this reason it important to consider topical therapy as much aspossible as use systemic antibiotics when really necessary. It is important tocontrol inflammation in the skin to minimize the conditions that could lead to thedevelopment of a bacterial infection. As a general rule, superficial pyodermashould be treated for a minimum of 3 weeks or at least 7-10 days pastresolut ion o f al l cl inical signs.A narrow spectrum antibiotic should bepreferred over a broad spectrum. Good choices for Staphylococcus would be firstgeneration cephalosporines, clindamycin, lincomycin. Other good choices wouldbe amoxicillin clavulanic acid keeping in mind that the dose used for skininfection is higher than the standard dose (22mg/kg BID vs the commonly used14mg/kg BID). Third generation cephalosporines are not better than firstgeneration to kill staphylococcus but can increase the risk for resistance due tothe broader spectrum of action.

Fluoroquinolones should not be used as first line of defense and only used whenreally necessary and indicated by bacterial culture. It is important to rememberthat this category of drugs is concentration dependent and not time dependent.Thus it is best to give one higher daily dose rather than two smaller daily doses inthe attempt to go above the mutation prevention concentration to minimize thelikelihood of antibiotic resistance. For deep infections, the average case wouldrequire 6-8 weeks of systemic antibiotic. Treatment should be continued for atleast 4 weeks p ast the resolut ion of al l cl inical signs.

When faced with patients that appear to constantly need antibiotics the first thingto establish is whether this is a recurrent infection, a persistent infection maybebecause it is a resistant infection. Did the patient ever clear? Do we know thisthrough a recheck or by owner report? If the patient cleared, how long did it taketo relapse? One rule that I use is the 2 week rule. If it takes less than 2 weeks torelapse I consider the relapse as a continuation of the previous infection. In most

8/9/2019 Manejo de Infecciones Recurrentes de La Piel Marsella

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cases, this is due to insufficient length of the antibiotic course. If it takes morethan 2 weeks, then it could be a new bout if infection. Then the appropriatequestion is: why is this happening? Clearly the patient has an underlying causethat either has not been diagnosed or properly addressed.

Due to the increase of antibiotic resistance we now recommend to culture alldogs with a chronic antibiotic history even if the infection is just a superficialinfection. In the past we would have assumed that the selection of acephalosporin would have been sufficient. Now we need a culture to help usselect the proper antibiotic. Out of necessity, we are also prescribing moreantibiotics like chloramphenicol, which had not been used for a long time. Due tothe infrequent use in the past, most staphylococcus is still sensitive tochloramphenicol. A frequently used dose is 50mg/kg TID. GI upset is commonand clients should be warned about the toxicity and strongly encouraged to usegloves when handling this drug. Another commonly seen adverse effect in largebreed dogs is peripheral neuropathy which manifests with ataxia and hind limb

weakness.

Topical therapy in the past was mostly used as adjunctive therapy. Currently, weare using topical therapy sometimes in substitution for systemic therapy, in caseswhere we have no systemic antibiotic left to use. Daily chlorhexidine whirlpoolbaths followed by topical stannous fluoride at 0.4% are used in patients in whomno other treatments are possible. Stannous fluoride is the main active ingredientof toothpaste and is highly bactericidal, virucidal, and fungicidal. In unpublishedin vitro studies at UF, 0.4% stannous fluoride was shown to be highly bactericidalagainst multi-drug resistant Staphylococcus. In clinical unpublished studies alower % of stannous fluoride was not found to be effective. This emphasizes theimportance of not diluting the product. It is important to apply it directly to the skinat 0.4%. Another topical frequently used in resistant cases is mupirocin. The bestresults are seen with twice daily application. Another topical treatment commonlyused is oxychlorine. This is the equivalent of topical bleach therapy sometimesimplemented in human medicine in children with Methicillin resistant Staphaureus. Oxychlorine (Vetericyn spray) has the advantage of not bleaching thecoat and surfaces and being less harsh on the coat and skin. It should be done2-3x/day for maximum benefit.

Finally, a word of caution in terms of possible transmission from dogs to humansand vice versa may be needed. Healthy owners should not worry about thepossibility of contracting an infection but elderly or severely immunosuppressedowners should exercise caution when handling dogs with draining tracts andhighly resistant infections. Although not common, such transmission has beenreported in the literature and we need to inform our clients about proper hygieneto minimize this possibility.