A retrospective study on the identification and antimicrobial susceptibility of bacteria isolated from dogs and cats with otitis externa

Tan, Ying Qi (2023) A retrospective study on the identification and antimicrobial susceptibility of bacteria isolated from dogs and cats with otitis externa. [Project Paper] (Submitted)

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Abstract

Otitis externa (OE) is a commonly encountered problem in veterinary clinics among dogs and cats. It is a multifactorial disease that poses challenges to identifying its underlying pathogenic causes and determining the appropriate course of treatment. This study aimed to (i) identify the bacteria isolated from dogs and cats with OE; and (ii) determine the antimicrobial susceptibility of the identified bacteria. The laboratory reports of bacteria culture and identification from ear swabs of dogs and cats with OE were retrieved from the bacteriology laboratory of the Veterinary Laboratory Services Unit over 5 years (August 2017 to July 2023). Missing information was retrieved from medical patient records at the University Veterinary Hospital. Data were analysed through descriptive statistics and the results were presented in frequencies and percentages. Overall, 145 cases with 55% in dogs (n=80) and 45% in cats (n=65) were diagnosed with OE. Predominantly, dogs with OE were ten to eleven years of age (29%), male (74%), intact (78%), erected ears (53%), of German Shepherd Dog (23%). In contrast, cats with OE were less than one year to two years of age (29%), male (69%), intact (51%), and of Domestic Shorthaired cats (26%). Unilateral OE was observed in most dogs (69%) and cats (68%) at the initial presentation, showing the main clinical sign of otorrhea (41% of dogs, 43% of cats) such as purulent discharges (53% of dogs, 48% of cats) and mucopurulent discharges (16% of dogs, 18% of cats). Pathogenic bacteria frequently isolated from dogs were Pseudomonas aeruginosa (27%), Proteus mirabilis (17%), and Staphylococcus spp. (S. intermedius and S. pseudintermedius) (10%). In cats, Staphylococcus spp. (28%), P. aeruginosa (19%), and Streptococcus canis (13%) were commonly identified. Through antimicrobial sensitivity testing (AST), there was a significant proportion of dogs (65%) and cats (56%) exhibited multidrug-resistant (MDR). For both cats and dogs, Gram-negative bacteria, specifically P. aeruginosa exhibited 100% resistance to many tested antibiotics, including amoxicillin/clavulanic acid, cephalexin and cefixime. The most commonly prescribed empirical antibiotic was polymyxin B as a topical ear preparation (28% in both dogs and cats) and amoxicillin/clavulanic acid as a systemic antibiotic (24% in dogs and 25% in cats). In this study, P. aeruginosa is a significant concern as it was identified as MDR bacteria in 98% of cases. The emergence of MDR has severely limited the availability of therapeutic choices and underscored the importance of performing bacterial culture and AST in guiding definitive treatment decisions.

Item Type:	Project Paper
Faculty:	Faculty of Veterinary Medicine
Depositing User:	Ms. Nordeena Abdul Aziz
Date Deposited:	30 Oct 2024 07:54
Last Modified:	30 Oct 2024 07:54
URI:	http://psaspb.upm.edu.my/id/eprint/2095

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