Reduction of Microbial Diversity During Artisanal Fermentation and Detection of Multidrug-Resistant Salmonella in Commercially Imported Beef in Puerto Rico

Artisanally produced embutidos are a culturally significant fermented meat product widely consumed in Puerto Rico, yet their microbiological safety remains largely uncharacterized. This preliminary study evaluated the effect of artisanal fermentation on microbial diversity and assessed the presence of potentially pathogenic and antimicrobial-resistant Proteobacteria in locally produced embutidos. Raw pork (locally sourced) and beef (commercially imported) were obtained from retail supermarkets and processed at a small-scale production facility under standard artisanal conditions. Surface sampling using RODAC contact plates on TSA, MAC, and SDA media was performed before and after fermentation. Fermentation reduced overall microbial diversity in both meat types. Two Gram-negative isolates recovered from pre-fermentation samples were characterized using selective and differential media (MAC, MSA, EMB) and the IMViC biochemical test series. A Salmonella species was presumptively identified from imported beef, and an Enterobacter species from locally sourced pork. Kirby-Bauer disk diffusion testing revealed that the Salmonella isolate was resistant to five antibiotics (ampicillin, methicillin, penicillin, streptomycin, tetracycline) and showed intermediate susceptibility to chloramphenicol and gentamicin. The Enterobacter isolate was resistant to five antibiotics (ampicillin, methicillin, penicillin, streptomycin, tetracycline) and showed intermediate susceptibility to chloramphenicol and gentamicin. Both isolates met MDR criteria, highlighting the need for enhanced microbiological oversight of artisanally produced embutidos in Puerto Rico.