Page 1531 - Clinical Small Animal Internal Medicine

166 Bacterial Pyodermas 1469

resistant to ciprofloxacin, clindamycin, erythromycin, generally recommended. When instituted as a sole
VetBooks.ir and trimethoprim sulfa (TMS); 69.9% were resistant to therapy for superficial bacterial folliculitis, daily use is
recommended.
tetracycline and gentamicin, and 57.3% were resistant to
Wipes and sprays are convenient for frequent use,
chloramphenicol.
If resistant superficial bacterial folliculitis is present and are a convenient sole therapy for intertrigo. These
with limited therapeutic options, consider daily topical preparations may include acids, such as acetic acid 2%
therapy prior to use of amikacin, rifampin, or chloram- or boric acid 2%, and alcohols for antimicrobial and
phenicol, as this may be sufficient to resolve the prob- drying effects. These drying ingredients are particu-
lem with minimal risk to the patient. Chloramphenicol larly helpful for intertrigo, but are painful if applied to
may be used with success in resistant cases, but vomit- ulcerative lesions. Chlorhexidine (2–4%) is commonly
ing and diarrhea can be frequent, and transient bone found in wipe and spray preparations, and nisin is
marrow suppression is possible but apparently rare. found in wipe preparations. Of note, chlorhexidine is
Reversible weakness (often seen in the hindlimbs) may appropriate for both gram‐positive and gram‐negative
occur in dogs. Clients must also wear gloves to prevent bacteria, whereas nisin is most appropriate for treat-
rare but fatal aplastic anemia of humans. At present, ment of staphylococci alone. For sole therapy, apply
resistance to rifampin is rare. Although it is often stated every 12–24 hours; for adjunct therapy, application
that a secondary antimicrobial is required with use of every 24–72 hours is appropriate.
rifampin, successful treatment with monotherapy has Hypochlorous acid is available in a convenient, com-
been documented with S. aureus and, therefore, this mercial spray formulation (Vetericyn VF®, Innovacyn). It
long‐held concept may not apply to treatment of staphy- can be used solely once to twice daily for localized
lococcal pyoderma. Hepatotoxicity can be life‐threaten- superficial and deep pyoderma or as an adjunct to other
ing and biochemistry values must be monitored every topical and systemic therapies for more generalized
seven days during administration. Given the potential conditions. Hypochlorous acid is the sodium salt of
for renal failure, amikacin is reserved for patients with sodium hypochlorite (household bleach). Dilute bleach
severe, deep, resistant pyoderma with no other rational rinse solutions (0.005–0.01%) are used by human and
systemic treatment options. When used, frequent uri- veterinary dermatologists, particularly for treatment of
nalysis and monitoring for casts are recommended. allergy‐induced recurrent and resistant staphylococcal
Although susceptibility to vancomycin, linezolid, pyoderma. The author uses a dilution of 2 tablespoons of
synercid (quinupristin/dalfopristin), and teicoplanin household bleach per gallon of water as a rinse. This
may be provided in antibiograms, use of these antibiotics effective and affordable therapy can be used after bath-
is strongly discouraged. These are drugs of last resort ing or applied directly to a focal area as frequently as
used for human MRSA patients with life‐threatening daily as a sole therapy or as infrequent as twice weekly as
infections and selection for further resistance must be an adjunct therapy. The patient is patted dry. Note that
avoided. this solution must be reconstituted daily. It is nonirritat-
ing, and there are some data to suggest it is antiinflam-
matory as well.
Topical Therapy
Creams, ointments, and gels are most appropriate
Adjunct topical therapy is indicated in all forms of pyo- for focal presentations. Many commercial antibiotic
derma and may be used as the sole treatment for surface preparations (neomycin, polymyxin B, gentamicin) are
pyodermas such as acute moist dermatitis and intertrigo, available combined with antifungal and corticosteroid
as well as with superficial pyodermas, including impe- ingredients. Concurrent use of a topical corticosteroid
tigo and superficial bacterial folliculitis. The use of topi- may obscure interpretation of antimicrobial response,
cal therapy may shorten the duration of systemic therapy, and chronic use may result in cutaneous atrophy and
and thus reduce antibiotic selective pressures. The ulceration. Creams and ointments containing an anti-
choice of topical ingredient(s) and formulation is microbial as the sole ingredient are therefore preferred.
dependent upon lesion location, distribution, type, and Active ingredients include silver sulfadiazine, benzoyl
compliance of the client and the animal. peroxide, fusidic acid, hydrogen peroxide, and mupi-
Shampoo therapy is ideally performed 2–3 times rocin. Of note, mupirocin ointment should not be used
weekly as an adjunct for all forms of pyoderma. Active routinely, as mupirocin resistance has been docu-
ingredients include chlorhexidine 2–4%, benzoyl per- mented, and it is used for decolonization of methicil-
oxide 2.5%, and ethyl lactate 10%. Benzoyl peroxide can lin‐resistant S. aureus of humans. For sole therapy,
be drying and is best used for patients with greasy or apply every 12–24 hours; for adjunct therapy, applica-
purulent dermatitis. A contact time of 5–10 minutes is tion every 48–72 hours is appropriate.