Enterobacteria in anaerobic digestion of dairy cattle wastewater: Assessing virulence and resistance for one health security.

Samples from a dairy cattle waste-fed anaerobic digester were collected across seasons to assess sanitary safety for biofertilizer use. Isolated enterobacteria (suggestive of Escherichia coli) were tested for susceptibility to biocides, antimicrobials, and biofilm-forming capability. Results revealed a decrease in total bacteria, coliforms, and enterobacteria in biofertilizer compared to the effluent. Among 488 isolates, 98.12 % exhibited high biofilm formation. Biofertilizer isolates exhibited a similar biofilm formation capability as effluent isolates in summer, but greater propensity in winter. Resistance to biocides and antimicrobials varied, with tetracycline resistance reaching 19 %. Of the isolates, 25 were multidrug-resistant (MDR), with 64 % resistant to three drugs. Positive correlations were observed between MDR and increased biofilm formation capacity in both samples, while there was negative correlation between MDR and increased biocide resistance. A higher number of MDR bacteria were found in biofertilizer compared to the effluent, revealing the persistence of E. coli resistance, posing challenges to food safety and public health.

Virulence factors and antimicrobial resistance of Escherichia coli isolated from commercialized fresh cheese in the south of Espírito Santo.

Cheeses are dairy products that can potentially contain a diverse range of harmful bacteria that could be consumed by humans, including the enteric pathogen Escherichia coli. This study aimed to characterize the presence of total coliforms, assess the antimicrobial susceptibility profiles of the main commercial antimicrobial classes and biocides, and evaluate the ability of 50 E. coli isolates obtained from fresh cheese sold in the southern region of Espírito Santo, Brazil, to produce biofilms. The counts of total coliforms + E. coli obtained averages of (A) 7.22 × 106 CFU/g, (B) 9.35 × 107 CFU/g, and (C) 1.16 × 106 CFU/g for different brands. All isolates were capable of forming biofilms, with 8%, 76%, and 16% of these isolates presenting high, moderate, and low adherence in biofilm formation, respectively. Most strains showed inhibition halos for the biocides chlorhexidine digluconate 2% (16 mm ± 4.34), iodopovidone 10% (7.14 mm ± 0.36), and sodium hypochlorite 2% (7.12 mm ± 0.33). Out of the 50 strains, 21 (42%) were resistant to at least one of the antimicrobials. Regarding the multiple resistance index, 3 (6%) strains were resistant to 3 or more antimicrobial classes. Furthermore, 2 (4%) were extended-spectrum beta-lactamases producers. Resistance to ampicillin and amoxicillin was observed in 20% and 40% of the strains, respectively. In contrast, gentamicin was the most effective antimicrobial, with a sensitivity rate of 100%. The findings indicate that E. coli present in fresh cheese may possess unique physiological characteristics that could be associated with their persistence, virulence, and multidrug resistance. These results raise significant public health concerns since contaminated food can pose risks to consumers' health, emphasizing the importance of reinforcing hygienic-sanitary controls at all stages of production.