Microbiological study of Otitis externa in Sheep in Diwaniya City

In this study, twenty eight Awassi sheep suffering from otitis externa were examined for isolation and identification of bacterical infections.The study showed 53.6% of the sheeps were positive for bacterical islates.The results showed that Pseudomonas aeruginosa was the most common bacteria (39,1%) followed by Staphylococcus aureus (26%) , Mannheimia haemolytica and Staphylococcus epidermidiis (13%) for each,while E.coli and Streptococcus spp. were less in common (1%) for each. Sensitivity tests of these isolate were studied and show highly sensitivity to ciprofloxacin and norfloxacin and highly resistant to Ampicillin. Introduction Otitis externa is a common disease in Cattle, Pigs and small animals (1, 2) but it is susceptible in lambs (3, 4). Otitis externa is an inflammation of the outer ear and ear canal characterized by an inflammation of the epithelium of the external auditory meatus (5, 6). Clinical signs such as exudates in conjunction with the isolation of bacterial species in large number are significance in most cases and may indicate the presence of pathogen (7, 8). Otitis externa has a multifactorial etiology and bacteria play an important role in otic disease (4,5). Most of the bacteria incriminated in ear infections include Staphylococcus spp. , Pseudomonas spp. , E.coli , Mannheimia haemolytica and Proteus can be recovered occasionally (9,10). In Iraq, there are little studies on the Otitis exerna in sheep; therefore the purpose of this study was to determine the bacterial agents that cause Otitis externa in sheep and its sensitivity to antibiotic. Material and Methods Sterile cotton swabs were used for collection of specimens from 28 animals suffered from Otitis externa (auricular discharge ,weakness,cough,bilateral nasal discharge) and transported to the laboratory.All specimens obtained were cultured for isolation and identification of the bacteria on the following media: 1.Blood agar. 2. Mac Conkey agar. 3.Chocolate agar. 4.Peptone water. 5.MR-VP media. 6.Triple sugar iron. 7.Urea medium. 8.Muller –Hinton ager. The reagents used for identification:1.H2O2 (catalase test) 2.1% tetra-methyl paraphynl diamine dihydrochloride (oxidase test). 3.Kovac’s reagent (indole test). 4.Gram’s stain. 5.Antibiotic disc. Bacteria isolates were identified according to Quinn et al (12). Results and Discussion A total of 28 Awassi sheep were suffered from Otitis Externa (auricular discharge, weakness, cough, bilateral nasal discharge) were enrolled in this study.The results showed that 15 (53.6%) animals were infected with bacterial species.Twenty three bacterial isolates were isolated from 15 specimens according to biochemical tests (Table 1). AL-Qadisiya Journal of Vet.Med.Sci. Vol./10 No./1 2011 33 Table (1) Biochemical reactions characteristic of bacterial species isolates Bacterial isolates Catalase production Oxidase production Indole production MR reaction Vp reaction Urease test Pseudomonas aeruginosa + + _ _ _ + Staphylococcus aureus + / / _ + ± Mannheimia haemolytica / + _ / / _ Staph. epidermidis + _ / / / + Escherichia coli + _ + + _ _ Streptococcus spp. + _ / / / _ As it shown in Table (2) P.aeruginosa were the predominant bacteria 9 (39.1%) followed by S.aureus 6(26%) and Manheimia haemolytica 3 (13%) ,S.epidermidis 3(13%) while E.coli and streptococcas spp. were less common 1(4.35%) for each. Table (2) Number and percentage of bacterial isolates from ear canal Bacterial species Number of isolates % Ps. aeruginosa 9 39.13 Staphylococcus aureus 6 26.08 Staph. epidermidis 3 13.04 M.haemolytica 3 13.04 Escherichia coli 1 4.35 Streptococcus spp 1 4.35