OBJECTIVES: To evaluate thermotolerance and antifungal susceptibility of feline Malaysian Sporothrix isolates, compare microdilution (MD) and E-test results, and investigate changes in susceptibility during azole therapy.
METHODS: Sporothrix schenckii sensu stricto was isolated from 44 cats. Thermotolerance was determined via culture at 37°C for 7 days. Susceptibility to itraconazole (ITZ), ketoconazole (KTZ) and terbinafine (TRB) was assessed in 40 isolates by MD; to amphotericin B (AMB), KTZ, ITZ, fluconazole (FLC) and posaconazole (POS) by E-test. Results were statistically compared by Pearson's Product Moment. In eight ketoconazole treated cats, susceptibility testing to itraconazole and ketoconazole was repeated every two months for six months.
RESULTS: Thermotolerance was observed in 36 of 44 (82%) isolates. Assuming that isolates growing at antifungal concentrations ≥4 mg/mL were resistant, all were resistant on E-test to FLC and AMB, 11 (28%) to POS, 6 (15%) to ITZ and 1 (3%) to KTZ. On MD, 27 of 40 (68%) were resistant to TRB, 2 (5%) to ITZ and 3 (8%) to KTZ. There was no correlation between E-test and MD results (KTZ r = 0.10, P = 0.54, and ITZ r = 0.11, P = 0.48). MD values for ITZ and KTZ did not exceed 4 mg/L during KTZ therapy.
CONCLUSION: The majority of feline isolates in Malaysia are thermosensitive. Lack of correlation between E-test and MD suggests that the E-test is unreliable to test antifungal susceptibility for Sporothrix spp. compared to MD. KTZ was the antifungal drug with the lowest MIC. Prolonged KTZ administration may not induce changes in antifungal susceptibility.
OBJECTIVES: To describe the treatment of cutaneous myiasis in three dogs caused by the larvae of Ch. bezziana in Malaysia and their treatment with spinosad plus milbemycin.
RESULTS: In all dogs, a single oral dose of spinosad plus milbemycin at the recommended dosage of 31-62 mg/kg and 0.5-1.0 mg/kg, respectively, was able to kill all larvae within 8 h. Most dead larvae fell off the host and those remaining on the host were dead and easily removed with simple saline flushing and gentle debridement. Neither general anaesthesia nor aggressive mechanical debridement were needed in any patient.
CONCLUSIONS AND CLINICAL IMPORTANCE: Oral spinosad plus milbemycin is a safe, licensed and effective treatment at the recommended dose for the rapid elimination of Ch. bezziana myiasis, with no need for sedation or anaesthesia.
OBJECTIVES: To describe clinical and epidemiological aspects of canine and feline screw-worm myiasis.
ANIMALS: Naturally infested dogs and cats, presented to five veterinary clinics in four Malaysian states from September 2017 to February 2018.
METHODS AND MATERIALS: Cutaneous screw-worm myiasis was diagnosed based on clinical signs and visual examination of burrowing larvae within lesion. Age, breed, gender, anatomical site of infestation and suspected underlying predisposing causes were investigated.
RESULTS: A total of 55 dogs and 21 cats were included in the study. Intact male mixed breed dogs (mean age 58 months) and intact male domestic short hair cats (mean age 24 months) with suspected fight-related wounds were most commonly presented with exudative and ulcerative lesions associated with screw-worm myiasis. The most common anatomical sites of infestation in the dogs were the external ear canals, followed by the perineum and medial canthus. For the cats, the most commonly affected areas were paws and tail. Five cats with screw-worm myiasis were concurrently infected with sporotrichosis.
CONCLUSION AND CLINICAL RELEVANCE: Aggression between unneutered animals is a likely underlying cause for cutaneous screw-worm myiasis in both cats and dogs. Sporotrichosis was also a potential predisposing cause for screw-worm myiasis in cats.
HYPOTHESIS/OBJECTIVES: To determine the in vitro interaction of ionophores (narasin or monensin) with antimicrobial adjuvants (N-acetylcysteine (NAC), Tris-EDTA or disodium EDTA) against bacterial strains representing pathogens associated with canine otitis externa (OE).
ANIMAL/ISOLATES: American Type Culture Collection (ATCC) strains Staphylococcus aureus 29213, Pseudomonas aeruginosa 27853 and P. aeruginosa biofilm producer PAO1, and a clinical isolate of Proteus mirabilis from a case of canine OE were tested.
METHODS AND MATERIALS: A 2D microdilution checkerboard method was used, allowing calculation of fractional inhibitory concentration index (FICI), dose reduction index (DRI) and plotting of isobolograms.
RESULTS: The combination of narasin with either Tris-EDTA or disodium EDTA produced additive effects (FICI = 0.75) against P. aeruginosa ATCC 27853 and P. aeruginosa biofilm producer ATCC PAO1. An additive effect (FICI = 0.53-0.75) was found against S. aureus ATCC 29213 when narasin or monensin were combined with NAC. The highest DRI (32-fold) was found with monensin/NAC where the MIC of monensin was reduced from 4 to 0.125 μg/mL.
CONCLUSIONS AND CLINICAL IMPORTANCE: The combination of narasin with Tris-EDTA or disodium EDTA is a promising strategy to inhibit the intrinsic resistance elements of Gram-negative bacteria. These novel combinations potentially could be useful as a multimodal approach to treat mixed infections in canine OE.