Molecular analysis, biochemical characterization, antimicrobial activity and immunological analysis of Proteus mirabilis isolated from broilers

Authors: Yeh, Hung-Yueh; Line, John; Hinton Jr, Arthur

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2017
Publication Date: 3/1/2018
Citation: Yeh, H., Line, J.E., Hinton Jr, A. 2018. Molecular analysis, biochemical characterization, antimicrobial activity and immunological analysis of Proteus mirabilis isolated from broilers. Journal of Food Science. 83(3):770-779. https://doi.org/10.1111/1750-3841.14056.
DOI: https://doi.org/10.1111/1750-3841.14056

Interpretive Summary: Proteus mirabilis is a flagellated Gram-negative bacterium and is ubiquitous in the environment. This bacterium is regarded as the normal microflora in the human lower digestive tract. However, this bacterium is also an opportunistic pathogen for human, causing urinary tract infection. Recently, Proteus has been frequently isolated from food animals, including poultry products. It is not known whether this bacterium contributes to the foodborne illness in human. In this report, P. mirabilis isolates recovered from broilers during housing in the units were characterized, their antimicrobial activity was assayed, and broiler immune response to the soluble proteins of the bacterium was determined. Cecal contents and fecal droppings were treated according to the standard protocol for isolation. Speciation based on biochemical reactions and the antimicrobial activity of the isolates were carried out using commercial kits. Western blot was used to determine immune status of broilers against P. mirabilis. A total of 10 isolates of P. mirabilis were recovered from both broiler ceca and feces. These isolates could grow in the pH 6.0 and 1% NaCl conditions. They were resistant to sodium lactate, troleandomycin, rifamycin SV, vancomycin, but sensitive to nalidixic acid. Moreover, the qnrA and qnrD genes were detected by PCR amplification in all isolates. Sera from broilers harboring this bacterium reacted to the P. mirabilis soluble proteins. This study may provide a rationale for further monitoring P. mirabilis in poultry products to determine whether this bacterium pose potential threatens to public health.

Technical Abstract: Proteus mirabilis, a peritrichously flagellated Gram-negative bacterium, is ubiquitous in the environment and is the normal microflora in the human gastrointestinal tract. However, this bacterium is an opportunistic pathogen for human, often causing urinary tract infection. Moreover, Proteus has been frequently isolated from food animals, particularly in poultry and its products. Whether this bacterium contributes to the foodborne illness in human is not clear. In this report, P. mirabilis isolates recovered from broilers during housing in the units were characterized, their antimicrobial activity was assayed, and broiler immune response to the Bicine-CHAPS soluble proteins was determined. Cecal contents and fecal droppings were treated according to the standard protocol for isolation. Speciation based on biochemical reactions was carried out using a Biolog Microbial ID System kit, and the antimicrobial activity of the isolates were carried out using Phenotype MicroArray kit. Western blot was used to determine immune status of broilers against P. mirabilis. A total of 10 isolates of P. mirabilis were recovered from both broiler ceca and feces after two weeks of age. These isolates could grow in the pH 6.0 and 1% NaCl conditions. They were resistant to sodium lactate, troleandomycin, rifamycin SV, vancomycin, but sensitive to nalidixic acid. Moreover, the qnrA and qnrD genes were detected by PCR amplification in all isolates. Sera from broilers harboring this bacterium did not react to the P. mirabilis soluble proteins. This study may provide a rationale for further monitoring P. mirabilis in poultry products to determine whether this bacterium pose potential threatens to public health.