Disinfectant and antimicrobial susceptibility studies of Staphylococcus aureus strains and ST398 and ST5 methicillin-resistant Staphylococcus aureus strains from swine mandibular lymph node tissue, commercial pork sausage…

Authors: BEIER, ROSS - Retired ARS Employee; Andrews, Kathleen - Kate; Hume, Michael; SOHAIL, MUHAMMAD - Weill Medical College - Cornell; Harvey, Roger; Poole, Toni; Crippen, Tawni - Tc; Anderson, Robin

Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/2021
Publication Date: 11/22/2021
Citation: Beier, R.C., Andrews, K., Hume, M.E., Sohail, M.U., Harvey, R.B., Poole, T.L., Crippen, T.L., Anderson, R.C. 2021. Disinfectant and antimicrobial susceptibility studies of Staphylococcus aureus strains and ST398 and ST5 methicillin-resistant Staphylococcus aureus strains from swine mandibular lymph node tissue, commercial pork sausage meat and swine feces. Microorganisms. 9(11). Article 2401. https://doi.org/10.3390/microorganisms9112401.
DOI: https://doi.org/10.3390/microorganisms9112401

Interpretive Summary: Staphylococcus aureus is a Gram-positive pathogenic bacterium that causes hospital and community diseases, septicemia, toxic shock syndrome, and gastrointestinal illness worldwide. Biocides (antiseptics and disinfectants) are used throughout the food chain, including in restaurants and hospitals for the control of pathogenic bacteria. This work investigated the presence of S. aureus strains in swine tissues and meat products and established a baseline understanding of the susceptibility of these strains to disinfectants and disinfectant components used commercially to control bacteria. The work is important because it has provided solid information on the interactions of S. aureus with food producing animals, and generated critical data on the role of disinfectants in helping assure ultimate safety of meat products reaching the consumer.

Technical Abstract: Aims: Staphylococcus aureus (S. aureus) causes hospital and community diseases, and gastrointestinal illness worldwide. Disinfectants are used throughout the food chain for pathogenic bacteria control. The aims were to (i) investigate S. aureus bioavailability in swine tissue and sausage, (ii) establish susceptibility values of strains to disinfectants, and (iii) determine the MRSA strains multilocus sequence type(s). Methods and Results: Antimicrobial and disinfectant susceptibility profiles were determined for 164 S. aureus strains isolated from swine feces, lymph tissue, and pork sausage. No antimicrobial resistance (AMR) was detected to daptomycin, nitrofurantoin, linezolid, and tigecycline, while a high AMR prevalence was determined to erythromycin (50.6%), tylosin tartrate (42.7%), and penicillin (72%), and tetracycline (68.9%). Lymph tissue and sausage meat strains had diverse resistance profiles. Methicillin-resistant S. aureus (MRSA) strains were found in lymph tissue and sausage meat, six MRSA strains were ST398, and one was ST5. About 17.5% of feces strains and 41.6% of combined lymph tissue and sausage meat strains were resistant to chlorhexidine. All strains were susceptible to triclosan and benzalkonium chloride, with no cross-resistance between antimicrobials and disinfectants. Six MRSA strains had elevated susceptibilities to 18 of 24 disinfectants. Conclusion: The use of formaldehyde and tris(hydroxylmethyl)nitromethane in disinfectant DC&R were not effective resulting in unnecessary chemicals in the environment. Didecyldimethylammonium chloride and benzyldimethylhexadecyammonium chloride were equally effective disinfectants. Significance and Impact of the Study: ST398 and ST5 MRSA can colonize humans and were found within swine tissue and pork sausage, and had elevated susceptibilities to 75% of disinfectants tested.