Bacterial susceptibility testings of the lower airways of diseased dogs]

Objective: In this retrospective study over 5 years the bacterial flora of the deep airways of diseased dogs was sampled using bronchioalveolar lavage and its in-vitro susceptibility to numerous antimicrobial agents was analysed. Material and methods: Susceptibility testing of bacterial isolates from 84 dogs performed from 2004 to 2009 were evaluated and compared to data collected in 1999/2000. Results: The 99 bacterial isolates comprised Pasteurella spp. (27.3%), Bordetella bronchiseptica (20.2%), Staphylococcus spp. (18.2%), Escherichia coli (15.2%), Klebsiella spp. (8.1%), Pseudomonas spp. (7.0%), and Streptococcus spp. (4.0%). Lavage samples of eight dogs revealed simultaneous occurrence of more than one species. The majority of the tested Bordetella bronchiseptica-isolates were susceptible to fluoroquinolones as well as tetracycline, doxycycline and polymyxin B. The number of amoxicillin/clavulanic acid- and chloramphenicol-resistant isolates decreased compared to 1999/2000. The increase of chloramphenicol-susceptible isolates was statistically significant. The tested Staphylococcus-isolates revealed a susceptibility to fluoroquinolones, amoxicillin, cephalexin, doxycycline, and polymyxin B. Compared to the earlier study, a major portion exhibited susceptibility to chloramphenicol and tetracycline. None of the Klebsiella spp. tested in 1999/2000 was resistant to enrofloxacin, whereas only 62.5% of the isolates examined during 2004-2009 were susceptible. A susceptibility of all tested Klebsiella-isolates was detectable with respect to polymyxin B. Regarding E. coli, none of the tested antibiotics revealed an in-vitro activity against all of the tested isolates. The increase of amoxicillin/clavulanic acid-resistant isolates was statistically significant. Conclusion and clinical relevance: The study demonstrates the benefits of bronchioalveolar lavage as a diagnostic tool to ensure a responsible utilisation of antibiotics. Most of the tested bacterial isolates were susceptible to fluoroquinolones.