Ultraviolet (UV-C) light-emitting diode (LED) light at a wavelength of 250–280 nm was used to disinfect skinless chicken breast (CB), stainless steel (SS) and high-density polyethylene (HD) inoculated with Salmonella enterica. Irradiances of 2 mW/cm² (50%) or 4 mW/cm² (100%) were used to treat samples at different exposure times. Chicken samples had the lowest Salmonella reduction with 1.02 and 1.78 Log CFU/cm² (p ≤ 0.05) after 60 and 900 s, respectively at 50% irradiance. Higher reductions on CB were obtained with 100% illumination after 900 s (>3.0 Log CFU/cm²). Salmonella on SS was reduced by 1.97 and 3.48 Log CFU/cm² after 60 s of treatment with 50% and 100% irradiance, respectively. HD showed a lower decrease of Salmonella, but still statistically significant (p ≤ 0.05), with 1.25 and 1.77 Log CFU/cm² destruction for 50 and 100% irradiance after 60 s, respectively. Longer exposure times of HD to UV-C yielded up to 99.999% (5.0 Log CFU/cm²) reduction of Salmonella with both irradiance levels. While UV-C LED treatment was found effective to control Salmonella on chicken and food contact surfaces, we propose three mechanisms contributing to reduced efficacy of disinfection: bacterial aggregation, harboring in food and work surface pores and light absorption by fluids associated with CB.

This research investigated the variations in the occurrence of Salmonella, STEC O157:H7 and non-O157 in the beef production chain in Colombia affected by seasons, hypothesizing that pathogen prevalence will be highest in the rainy season owing to soil moisture promoting bacteria multiplication and transfer between animals. To test this hypothesis, samples were obtained from five abattoirs, which represent 50% of the beef production in this country. A total of 1017 samples were collected, from which 606 were bovine feces, 206 were hide swabs, and 205 corresponded to carcass post-intervention. From the 1017 samples, 49.9% (n = 507) were collected during dry season, while 50.1% (n = 510) during rainy season. All samples (n = 1017) underwent screening for E. coli O157:H7 and Salmonella, while only a proportion of fecal samples (n = 339) were screened for the big six STEC serogroups and their virulence markers. The effect of season, age of animal and sex of animal were correlated with the prevalence results. A total of 84.7% of fecal samples carried virulence genes associated to STEC (stx or eae), suggesting that testing and control should be increased for the big-six STEC compared to E. coli O157:H7. Pathogen prevalence in feces was found to be 8.3%, 5.0%, and 51.0% for Salmonella, E. coli O157:H7 and STEC non-O157, respectively. Hides had a prevalence of 15.0% and 6.8% of Salmonella and E. coli O157:H7, respectively. Carcasses post-intervention were found to have 4.4% and 2.5% prevalence of Salmonella and E. coli O157:H7, respectively. A seasonal effect was found for fecal samples. E. coli O157 and non-O157 STEC shedding were significantly higher (P ≤ 0.05) during rainy season compared to dry season. In contrast, hides and carcasses were more likely to present lower incidence of pathogens during rainy months compared to dry season; however, it was significant only for Salmonella on carcasses with estimated odds of detection almost six times higher in the dry season relative to the rainy season (OR = 5.90, 95% CI 1.18–29.57).

Staphylococcus aureus is a bacterial pathogen of considerable significance in public health, capable of inducing a diverse range of infectious diseases. One of the most notorious mechanisms used by S. aureus to survive and colonize the site of infection is its ability to form biofilms. Diflunisal, a non-steroidal anti-inflammatory drug (NSAID), is a known inhibitor of the Agr system in S. aureus, which is key in regulating biofilm formation. This study evaluated the effect of broad-spectrum antibiotics in combination with diflunisal on S. aureus biofilm density. Eight antibiotics were tested independently at different concentrations and in combination with diflunisal to assess their effect on S. aureus biofilm formation. When using the antibiotics alone and with diflunisal, a significant control effect on biofilm formation was observed (p < 0.05), irrespective of diflunisal presence, but did not achieve a complete biofilm growth inhibition. Over time, diflunisal influenced biofilm formation; however, such an effect was correlated with antibiotic concentration and exposure time. With amikacin treatments, biofilm density increased with extended exposure time. In the case of imipenem, doripenem, levofloxacin, and ciprofloxacin, lower doses and absence of diflunisal showed higher control over biofilm growth with longer exposure. However, in all cases, diflunisal did not significantly affect the treatment effect on biofilm formation. In the absence of antibiotics, diflunisal significantly reduced biofilm formation by 53.12% (p < 0.05). This study suggests that diflunisal could be a potential treatment to control S. aureus biofilms, but it does not enhance biofilm inhibition when combined with antibiotics.

Staphylococcus aureus is a common causative agent of mastitis in dairy cattle, posing a substantial threat to animal health and resulting in significant economic losses. Preventive measures are usually in place to control the spread of the organism between animals and around the dairy environment; however, mastitis outbreaks can still be recurrent. During this investigation, a total of 30 S. aureus isolates were obtained from six deceased cows, all diagnosed with chronic mastitis during an outbreak in West Texas. The aim of this study was to evaluate the response of the S. aureus isolates causing severe mastitis infections to iodine treatments and their antibiotic susceptibility, planktonic growth, and biofilm formation. Udder skin was inoculated with S. aureus and subjected to various iodine concentrations of 0.25%, 0.38%, 0.50%, 0.75%, and 1.00%, with exposure times of 15 s, 10 s, and 60 s. The same concentrations were tested on S. aureus’s biofilm formation. The results of the antimicrobial susceptibility test indicate that the exposure time did not influence the treatment. Lower iodine concentrations were compared with 1.00%, as the standard treatment used by the dairy for teat disinfection, and statistical difference (p < 0.001) was evident in the 0.00% iodine treatment compared to the other iodine concentrations. Moreover, a significant difference (p < 0.001) emerged when comparing the 0.25% and 0.38% iodine concentrations with 1.00%. No difference (p > 0.161) was detected between 0.50%, 0.75%, and 1.00%. These results suggest that, under the conditions investigated, iodine can be lowered to around 50% of the currently used dose without negatively impacting microbial control. On the other hand, S. aureus strains were susceptible to the tested antibiotics, demonstrating that antimicrobial resistance does not always play a role in the persistent mastitis infections caused by S. aureus. Further microbial phenotypic typing conducted on S. aureus strains indicated a possible common source of the infections, demonstrating the potential of there being resident S. aureus strains at this dairy farm.

Dehydrated alginate beads formulated with copper were synthesized and tested as a feed additive to influence the microbiota in finishing pigs and potentially use them as a preharvest intervention to reduce fecal pathogen shedding. The efficacy of the copper beads was tested in vitro and in vivo. In vitro , Salmonella was significantly ( P < 0.05) reduced when in contact with the copper beads solution for up to 6 h, with a 5.4 log CFU/mL reduction over the first hour. Chemical analysis of the soak solutions demonstrated the beads delivered their copper payload gradually over the same period the bactericidal effect was observed. For the in vivo experiments, pigs ( n = 48) supplemented with the copper beads experienced significant shifts in their microbiota. Enterobacteriaceae (EB) increased by 1.07 log CFU/g ( P < 0.05), while lactic acid bacteria (LAB) decreased by 1.22 log CFU/g ( P < 0.05) during the treatment period. When beads were removed from the feed, EB and LAB concentrations returned to baseline, indicating copper beads led to measurable and significant changes in microbial loads. Fecal microbiome analysis conducted to explore additional changes by copper bead supplementation demonstrated that, at the phylum level, there was an increase in Firmicutes, Euryarchaeota, and Acidobacteriota, while at the genus level, an increase in Methanosphaera and Pseudomonas was observed. Measures of copper in swine feces showed values ~20 times higher in the treatment group than in the control group during the treatment period, suggesting that dehydrated alginate copper beads were effective in delivering antimicrobial copper to the animal hindgut. IMPORTANCE: Copper has long been known to have antimicrobial properties. However, when water-soluble salts are fed to livestock, the copper may rapidly dissolve in gastric contents and fail to reach the gut. Here, specially formulated copper beads are seamlessly incorporated into feed and allow copper to remain longer in the gastrointestinal tract of animals, reach deep into both the foregut and hindgut, and shift microbial populations. The technology delivers antimicrobial copper to the animal hindgut and potentially reduces pathogenic microorganisms before animal slaughter.