Abstract
Staphylococcus aureus (S. aureus) causes gastrointestinal illness worldwide. Disinfectants are used throughout the food chain for pathogenic bacteria control. We investigated S. aureus bioavailability in swine Mandibular lymph node tissue (MLT) and pork sausage meat (PSM), established susceptibility values for S. aureus to disinfectants, and determined the multilocus sequence type of MRSA strains. Antimicrobial and disinfectant susceptibility profiles were determined for 164 S. aureus strains isolated from swine feces (n = 63), MLT (n = 49) and PSM (n = 52). No antimicrobial resistance (AMR) was detected to daptomycin, nitrofurantoin, linezolid, and tigecycline, while high AMR prevalence was determined to erythromycin (50.6%), tylosin tartrate (42.7%), penicillin (72%), and tetracycline (68.9%). Methicillin-resistant S. aureus (MRSA) strains, ST398 (n = 6) and ST5 (n = 1), were found in the MLT and PSM, 4 MRSA in MLT and 3 MRSA strains in the PSM. About 17.5% of feces strains and 41.6% of MLT and PSM 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 disinfectants. The use of formaldehyde and tris(hydroxylmethyl)nitromethane in DC&R was not effective, which can add chemicals to the environment. Didecyldimethylammonium chloride and benzyldimethylhexadecylammonium chloride were equally effective disinfectants. ST398 and ST5 MRSA strains had elevated susceptibilities to 75% of the disinfectants tested. This study establishes susceptibility values for S. aureus strains from swine feces, mandibular lymph node tissue, and commercial pork sausage against 24 disinfectants. Since it was demonstrated that S. aureus and MRSA strains can be found deep within swine lymph node tissue, it may be beneficial for the consumer if raw swine lymph node tissue is not used in uncooked food products and pork sausage.
Highlights
Staphylococcus aureus (S. aureus) is a Gram-positive bacterial pathogen important worldwide because of its human health effects [1,2,3,4,5]
The current study evaluated the susceptibility of 164 S. aureus strains isolated from swine feces, swine mandibular lymph node tissue (MLT), and commercial pork sausage meat (PSM) against antimicrobials, disinfectants, and 7 disinfectant components
The individual S. aureus antimicrobial resistance (AMR) profiles for strains from swine feces is presented in Supplementary Table S1, the AMR profiles for the strains from the Mandibular lymph node tissue (MLT) are in Supplementary Table S2, and the AMR profiles for the strains isolated from the PSM are in Supplementary Table S3
Summary
Staphylococcus aureus (S. aureus) is a Gram-positive bacterial pathogen important worldwide because of its human health effects [1,2,3,4,5]. The Centers for Disease Control (CDC) has selected S. aureus as one of the top five pathogens causing foodborne illness in Microorganisms 2021, 9, 2401. MRSA is resistant to all penicillins [13] and commonly exhibits resistance to most β-lactams [18], such as amoxicillin and oxacillin, resulting in limited treatment options for MRSA infections [18,19]. An emerging S. aureus strain referred to as borderline oxacillin-resistant S. aureus (BORSA) does not have PBP2a and cannot be either classified as methicillin-resistant or methicillin-susceptible [20]. BORSA resistance results from hyperproduction of beta-lactamases or point mutations. They may be misidentified causing a therapeutic threat. MRSA infections are a major problem, especially MRSA-associated bacteremia, which is a cause of endocarditis and sepsis resulting in morbidity and mortality [21]
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