Prevalence and Antibiotic Sensitivity of Motile Aeromonas in Dogs

Ceylan E. , M. Berk tas , H. Korkoca , I . Keles , H. Bozkur t , M. G. Kur toglu : Prevalence and Antibiotic Sensitivity of Motile Aeromonas in Dogs. Acta Vet. Brno 72, 2003: 607-612. The present study was carried out to assess the prevalence of motile Aeromonas sp. in the faeces of healthy dogs and to evaluate its susceptibility to some anti-microbial agents. Rectal swabs from 55 domestic dogs were examined for Aeromonas species using alkaline peptone water (pH 8.4) as the enrichment medium and Aeromonas Selective Agar containing 5 mg/l ampicillin as the plating medium. Identification and antibiotic resistance of motile Aeromonas strains was performed using Gram Negative Breakpoint ID panel. After examining these samples, aeromonads were isolated from three (5.45%) dogs. Of those, one was A. sobria, and two were A. caviae. While all isolated strains were sensitive to amikacin, cefoperazone, cefotaxime, cefotetan, ceftazidime, ceftriaxone, cefuroxime, ciprofloxacin, gentamicin, imipenem, piperacillin, tetracycline, ticarcillin, ticarcillin/clavulanate, tobramycin, and trimethoprim/sulfamethoxazole, they were resistant to ampicillin, and ampicillin/sulbactam. In addition, a strain of A. caviae was also resistant to aztreonam. As a result, in the present study, information about the prevalence of Aeromonas in dogs, susceptibility to antibiotics of these microorganisms and its importance for both animal and public health were discussed. Aeromonas, dog, prevalence, antibiotic sensitivity Aeromonas spp. are gram-negative rods commonly found in freshwater sewage and soil (Quinn et al. 1994). Species of the genus Aeromonas have long been recognized as pathogens of amphibians and reptiles (Shot ts et al. 1972), fish and snail (Popoff 1984). Known risk factors for disease in humans include drinking or swimming in contaminated water and also ingestion of contaminated food. Direct contact with contaminated animals and using ineffective antimicrobial agents are the other risk factors. Foods of animal origin and contaminated animals may play an important role in the transmission of the aeromonads from food or animals to humans, and animal faeces appear to be the major source of contamination of foods (Moyer 1987; J indal et al. 1993). The isolation of motile aeromonads from dog faeces has been reported in a few studies. Aeromonas species in the faeces of domestic dogs may pose a public health problem for humans who come into contact with such animals (Akan et al. 1996; Ghenghesh et al. 1999). Therefore, the present study was carried out to assess the prevalence of motile Aeromonas sp. in the faeces of healthy dogs and to evaluate its susceptibility to some antimicrobial agents. Materials and Methods Dog Faecal Specimens Faecal specimens were obtained from 55 healthy dogs randomly for the isolation of motile aeromonads using sterile swabs. The specimens collected were immediately transported to the laboratory in Alkaline peptone water (APW). ACTA VET. BRNO 2003, 72: 607–612 Address for correspondence: Dr. Ebubekir CEYLAN Posta Kutusu 139, 65000-VAN, TURKEY Phone: +0532-205 16 00 Fax: +0432-215 52 81 E-mail: bekirceylan@lycos.com http://www.vfu. cz/acta-vet/actavet.htm Isolat ion Media APW (pH:8.4) was used for enrichment medium, and Aeromonas Selective Agar (Oxoid, CM833) containing 5 mg·l-1 ampicillin was used as selective differential plating medium for Aeromonas spp. (Ampicillin Selective Supplement, SR136). Oxidase tes t This test was performed using oxidase identification sticks (Oxidase BR 64, Oxoid). Catalase tes t A small amount of a suspected colony was placed on a microscope slide and a drop of catalase reagent (hydrogen peroxide, 3%) was added. When the colony was catalase-positive, gas bubbles were produced and test was evaluated as positive. Oxidat ion – Fermentat ion (O-F) Test O/F test was performed with oxidation-fermentation basal medium (Difco, D0688-02). Before use, 2 tubes of O/F medium, with loosened caps, were heated in a beaker of boiling water to drive off dissolved oxygen. After steaming for a few minutes, the tubes were cooled rapidly under cold running water. Both tubes of media were stab inoculated with the test organism, using a straight wire. Immediately added a layer of sterile paraffin oil to a depth of about 1 cm on the top of one of the tubes. Then, incubated at 37 oC for up to 14 days. The results were evaluated by the colour change on the tubes. Development of a yellow colour in tubes with and without oil was considered as positive reaction. Sceptor Gram-Negat ive Breakpoint ID Panel Identification of motile Aeromonas strains was based on following biochemical reactions in Gram-Negative Breakpoint ID Panel (Sceptor Panel Code: 280 430, Becton Dickinson, USA): Citrate, Polymixin B, Dextrose, Malonate, Esculin, PNPG, Lysin, Arginine, Ornithine, Urea, H2S, Indol, Rhamnose, Melibiose, Mannitol, Arabinose, Xylose, Sucrose, Dnase, NPC, Glycin. These biochemical tests were confirmed by conventional biochemical tests. The VP (Voges-Proskauer) tes t Strains were inoculated into the Clark-Lubs medium and incubated for 24 h at 37 oC. One ml of medium taken from this inoculate was transferred to a sterile tube. Then 0.6 ml alpha naphtol, thereafter 0.2 ml KOH added to the tube and then mixed well before waiting for 10-15 min. The test result was assessed as positive when red colour developed. Isolat ion and Ident i f icat ion Faecal specimens obtained with sterile swabs were inoculated into 10 ml of alkaline peptone water (APW, pH 8.4) for the purpose of enrichment, and incubated for 24 h at 28 oC. Then, incubated material was inoculated into Aeromonas Selective Agar and incubated for 24 h at 37 oC. Growing bacteria colonies in the medium were examined for oxidase and catalase positive, fermentative, motile, Gram-negative rods. Positive samples for these tests were identified as Aeromonas spp. using the Sceptor GramNegative Breakpoint ID Panel (Beckton-Dickinson, USA) and biochemical tests. The Voges-Proskauer (VP) test was performed to the strains identified as A. hydrophila/caviae in the Sceptor Gram Negative Breakpoint ID Panel. VP negative strains were identified as A. caviae. Sensi t ivi ty to ant imicrobial agents Sensitivity tests on the identified Aeromonas spp. were performed with the Sceptor Gram Negative Breakpoint ID Panel (Panel code:280 430, Becton Dickinson-USA). With this panel, their sensitivity to amikacin, amoxicillinclavulanate, ampicillin, ampicillin-sulbactam, aztreonam, cefazolin, cefoperazone, cefotaxime, cefotetan, ceftazidime, ceftriaxone, cefuroxime, ciprofloxacin, gentamicin, imipenem, piperacillin, tetracycline, ticarcillin, ticarcillin-clavulanate, tobramycin, and trimethoprim-sulfamethoxazole were examined. The results were confirmed using by Kirby-Bauer disc diffusion method in agreement with recommendation of the NCCLS.