The probiotic potential and antimicrobial activity of Lactiplantibacillus plantarum, Saccharomyces cerevisiae, and Bifidobacterium longum were investigated against Escherichia coli O157:H7, Salmonella typhimurium and Listeria monocytogenes. Selected strains were subjected to different acid levels (pH 2.5–6.0) and bile concentrations (1.0–3.0%). Strains were also evaluated for their antimicrobial activity by agar spot test. The potential probiotic strains tolerated pH 3.5 and above without statistically significant growth reduction. However, at pH 2.5, a significant (p < 0.05) growth reduction occurred after 1 h for L. plantarum (4.32 log CFU/mL) and B. longum (5.71 log CFU/mL). S. cerevisiae maintained steady cell counts for the entire treatment period without a statistically significant (p > 0.05) reduction (0.39 log CFU/mL). The results indicate at 3% bile concertation, 1.86 log CFU/mL reduction was observed for L. plantarum, while S. cerevisiae, and B. longum growth increased by 0.06 and 0.37 log CFU/mL, respectively. L. plantarum and B. longum demonstrated antimicrobial activity against E. coli O157:H7, S. typhimurium and L. monocytogenes. However, S. cerevisiae did not display any inhibition to any of the pathogens. The results indicate that L. plantarum and B. longum present probiotic potential for controlling E. coli O157:H7, S. and L. monocytogenes in poultry.

This study investigated the prevalence of antimicrobial-resistant bacteria in retail edible offal and muscle meats in Nashville, Tennessee. A total of 348 retail meats (160 edible offal and 188 muscle) were analyzed for Salmonella enterica serovar, Campylobacter, Escherichia coli, E. coli O157:H7, and enterococci. Bacteria was identified using biochemical and PCR methods. Salmonella enterica serovar (4.4% and 4.3%), Campylobacter (1.9% and 1.1%), E. coli (79.4% and 89.4%), and enterococci (88.1% and 95.7%) was detected in offal and muscle meats, respectively. Chicken liver (9.7%) was most frequently contaminated with Salmonella enterica serovar, followed by ground chicken (6.9%) and chicken wings (4.2%). No Salmonella enterica serovar was detected in beef liver, beef tripe, and ground beef. The prevalence of Campylobacter was 6.9%, 2.3%, and 1.4% in beef liver, ground beef, and ground chicken, respectively. None of the meats were positive for E. coli O157:H7. Resistance of isolates was significantly (p < 0.05) highest in erythromycin (98.3%; 99.1%), followed by tetracycline (94%; 98.3%), vancomycin (88.8%; 92.2%) as compared to chloramphenicol (43.1%; 53.9%), amoxicillin/clavulanic (43.5%; 45.7%), and ciprofloxacin (45.7%; 55.7%) in offal and muscle meats, respectively. Imipenem showed the lowest resistance (0%; 0.9%). A total of 41 multidrug-resistant patterns were displayed. Edible offal could be a source of antibiotic-resistant bacteria.

The production and consumption of organic fresh produce have constantly increased since the 1990s. Consumers prefer organic produce because it does not contain synthetic chemical residues that are often implicated in health problems. The contamination of fresh produce by pathogenic Enterobacteriaceae strains remains a major challenge, and is responsible for frequent foodborne disease outbreaks. The use of antibiotics has proved an effective treatment, but the increase in occurrences of antibiotic resistance is becoming a health challenge. This study seeks to establish the presence of antimicrobial resistance in Enterobacteriaceae on organic and conventional watermelon fruits. Watermelons used for this study were cultivated at the Tennessee State University Certified Organic Farm, Nashville. At harvest, nine fruits were selected from among fruits lying on plastic mulch, and nine from fruits lying on the soil of both organic and conventional plots. These were placed in sterile sample bags for microbial analysis. Spread plating technique, API 20E, and apiweb software were used for microbial isolation and identification. Identified strains were tested for antimicrobial resistance against 12 common antibiotics. Seventeen Enterobacteriaceae strains were isolated and identified. Isolates were susceptible to gentamycin, ciprofloxacin, and chloramphenicol, but were resistant to cefoxitin. Citrobacter freundii showed a 14.3% resistance to Streptomycin. Pantoea spp. and Providencia rettigeri showed 50% and 100% resistance to tetracycline. Findings from this study confirm the presence of antibiotic-resistant Enterobacteriaceae strains on organic watermelons in Nashville, TN.