Porphyromonas gulae is a major periodontal pathogen in dogs, which can be transmitted to their owners. A major virulence factor of P. gulae consists of a 41-kDa filamentous appendage (FimA) on the cell surface, which is classified into three genotypes: A, B, and C. Thus far, inhibition of periodontal disease in dogs remains difficult. The present study assessed the inhibitory effects of a combination of clindamycin and interferon alpha (IFN-α) formulation against P. gulae and periodontal disease. Growth of P. gulae was significantly inhibited by clindamycin; this inhibition had a greater effect on type C P. gulae than on type A and B isolates. In contrast, the IFN-α formulation inhibited the expression of IL-1β and COX-2 elicited by type A and B isolates, but not that elicited by type C isolates. Furthermore, periodontal recovery was promoted by the administration of both clindamycin and ifn-α formulation to dogs undergoing periodontal treatment; moreover, this combined treatment reduced the number of fimA genotypes in oral specimens from treated dogs. these results suggest that a combination of clindamycin and ifn-α formulation inhibit P. gulae virulence and thus may be effective for the prevention of periodontal disease induced by P. gulae.
Case summaryA 14-year-old female spayed cat was referred for recurrent otitis externa and unusual proliferative lesions in both ear canals. The affected pinnae and external ear canals were covered with large reddish-to-dark-brown verrucous and necrotic tissue. Friable material and exudates occluded both ear canals. Proliferative lesions developed in both ears 2–3 weeks before referral. The histopathological diagnosis from two biopsies obtained from the friable materials with endoscopic biopsy forceps was proliferative and necrotising otitis externa (PNOE). Treatment was initiated with once-daily application of a potent topical glucocorticoid (mometasone furoate) to both ears. Although the auricle and vertical ear canals responded well, no improvement was seen in the horizontal part of the ear canal after 9 weeks. Therefore, oral triamcinolone (0.9 mg/kg q24h) was added for 1 week, and was then tapered (q48h) for 3 weeks. Most lesions resolved, and after a further 2 weeks of prednisolone (2 mg/kg q48h) there was complete resolution. No recurrence was observed during a 2 year follow-up period.Relevance and novel informationPNOE commonly occurs in kittens, but it can develop in older cats. To our knowledge, the PNOE in this case is the oldest age of onset reported. This condition is rare and was only described recently, and therapeutic options appear limited. According to previously published reports, steroid therapy is ineffective, and tacrolimus is the only treatment known to achieve resolution. However, oral and topical glucocorticoids were beneficial in this case.
Proliferative and necrotising otitis externa (PNOE) is a very rare disease affecting the
ear canals and concave pinnae of kittens. This report describes a 5-month-old cat with
PNOE. Histopathological examination confirmed the diagnosis. Treatment was initiated with
local injection of methylprednisolone acetate into the lesions. The cat was subsequently
treated with clobetasol propionate cream, a potent topical glucocorticoid ointment. The
cat showed marked improvement. While topical treatment with tacrolimus, an
immunosuppressive agent, is reported to be an effective therapy, to the best of our
knowledge, this is the first report to treat PNOE with local corticosteroid therapy.
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