Evaluating synergy between marbofloxacin and gentamicin in Pseudomonas aeruginosa strains isolated from dogs with otitis externa

Abstract

The aim of this study was to determine antimicrobial susceptibility of Pseudomonas aeruginosa strains to marbofl oxacin and gentamicin, and investigate the possible synergistic, additive, indifferent or antagonistic effects between the two agents. P. aeruginosa strains can develop resistance quickly against certain antibiotics if used alone, thus the need emerges to fi nd synergistic combinations. A total of 68 P. aeruginosa strains isolated from dogs were examined. In order to describe interactions between marbofl oxacin and gentamicin the checkerboard microdilution method was utilized. The MICs (minimum inhibitory concentrations) for marbofl oxacin and gentamicin were in the range 0.25-64 mg/L and 0.25-32 mg/L, respectively. The combination of marbofl oxacin and gentamicin was more effective with a MIC range of 0.031-8 mg/L and a MIC 90 of 1 mg/L, compared to 16 mg/L for marbofl oxacin alone and 8 mg/L for gentamicin alone. The FIC (fractional inhibitory concentration) indices ranged from 0.0945 (pronounced synergy) to 1.0625 (indifference). Synergy between marbofl oxacin and gentamicin was found in 33 isolates. The mean FIC index is 0.546, which represents a partial synergistic/additive effect close to the full synergy threshold. In vitro results indicate that marbofl oxacin and gentamicin as partially synergistic agents may prove clinically useful in combination therapy against P. aeruginosa infections. Although marbofl oxacin is not used in the human practice, the interactions between fl uoroquinolones and aminoglycosides may have importance outside the veterinary fi eld.

Pseudomonas spp. in Canine Otitis Externa

“…One study investigated the use of new antibiotic, ticarcillin in treatment-resistant cases, resulting in the initial resolution of 11 out of 12 cases, although two of these later relapsed [129]. More recently, synergy and partial synergy were reported when a combination of polymyxin B/miconazole and marbofloxacin/gentamicin was tested on P. aeruginosa canine otitis isolates [130,131].…”

Uso das fluoroquinolonas em cães e gatos domésticos

“…Não é apropriada para o tratamento de infecções moderadas ou graves por Staphylococcus spp., pois pode ocorrer resistência durante o tratamento (Jong, et al, 2018). Dos agentes de segunda geração, a ofloxacina apresenta maior ação contra a Chlamydia trachomatis, no entanto a ciprofloxacina é o fármaco mais utilizado, devido à disponibilidade em formulações orais e intravenosas e ao amplo conjunto de indicações marcadas pelo FDA (Jerzsele & Pásztiné-Gere, 2015).…”

“…Em dose duas vezes superior ao limite, a marbofloxacino provocou danos articular em cães de 4-5 meses de idade. Em gatos de oito meses de idade, que utilizaram as doses entre 17 e 28 mg/kg por 42 dias, por via articular, a marbofloxacino foi associada a dano cartilaginoso (Jerzsele & Pásztiné-Gere, et al, 2015).…”

“…As taxas de resistência aos antibióticos em animais de companhia aumentaram ao longo dos anos, e esse acréscimo acompanhou a utilização mais frequente de antimicrobianos no tratamento de infecções nesses animais, sem a certeza da real necessidade, já que exames para a identificação bacteriana e a susceptibilidade antimicrobiana muitas vezes não são realizados (Jerzsele & Pásztiné-Gere, 2015).…”

Uso de antibióticos na medicina veterinária brasileira: situação e regulamentação

“…PÁSZTINÉ-GERE, 2015). Corroborando com isso, 12% de 181 médicos veterinários de pequenos animais, na África do Sul, afirmaram que os tutores/responsáveis chegam à clínica já tendo tratado os animais por conta própria previamente.…”