Bacteria in Animal Feed and Their Susceptibility to Antimicrobial Drugs

Abstract

Control of microbiological safety of animal feed is regulated by a law. The regulation is based on methodological standards for estimation of feed quality. Those methods are permanently amended and strive for continuous improvement of microbiological safety of feed. The question remains whether the presence or absence of some bacterial species is sufficient for proper assessment of feed safety. The answer to this question can be found not only in the examination of the number of bacteria in animal feed, but also in qualitative analysis of the isolated microorganisms. The sensitivity of bacteria from animal feed to antimicrobials is one of the qualitative characteristics of microorganisms that can affect food safety even if the feed meets the standards and is within the maximum permitted level. The subject of our work was to determine the presence of bacteria in animal feed with a purpose to examine if they possess lower sensibility to antibiotics. For testing antibiotic sensitivity the isolates from routine microbiological feed control were used. The animal feed was analysed by the standard methods for the isolation and identification of bacteria and determination of susceptibility was done using disc diffusion method according to CLSI. The following bacteria were detected: Escherichia coli, Enterobacter sp., Staphylococcus sp., Micrococcus sp., Bacillus cereus, Bacillus sp. The results showed that some isolates have reduced susceptibility to certain antimicrobial drugs (The resistance is different for different antibiotics and microorganism - from 8,33% to 100%). This finding gives a reason for further examination of certain characteristics of the bacteria found in animal feed and to detect their possible influence on ecology.