Molecular characterization and biofilm-formation analysis of Listeria monocytogenes, Salmonella spp., and Escherichia coli isolated from Brazilian swine slaughterhouses

Abstract

This study aimed to verify the presence of Listeria monocytogenes, Salmonella spp., and Escherichia coli in two Brazilian swine slaughterhouses, as well as to perform antibiograms, detect virulence and antimicrobial resistance genes, and evaluate the in vitro biofilm-forming capability of bacterial isolates from these environments. One Salmonella Typhi isolate and 21 E. coli isolates were detected, while L. monocytogenes was not detected. S. Typhi was isolated from the carcass cooling chamber’s floor, resistant to several antimicrobials, including nalidixic acid, cefazolin, chloramphenicol, doxycycline, streptomycin, gentamicin, tetracycline, and sulfonamide, and contained resistance genes, such as tet(B), tet(C), tet(M), and ampC. It also showed moderate biofilm-forming capacity at 37°C after incubating for 72 h. The prevalence of the 21 E. coli isolates was also the highest on the carcass cooling chamber floor (three of the four samplings [75%]). The E. coli isolates were resistant to 12 of the 13 tested antimicrobials, and none showed sensitivity to chloramphenicol, an antimicrobial prohibited in animal feed since 2003 in Brazil. The resistance genes MCR-1, MCR-3, sul1, ampC, clmA, cat1, tet(A), tet(B), and blaSHV, as well as the virulence genes stx-1, hlyA, eae, tir α, tir β, tir γ, and saa were detected in the E. coli isolates. Moreover, 5 (23.8%) and 15 (71.4%) E. coli isolates presented strong and moderate biofilm-forming capacity, respectively. In general, the biofilm-forming capacity increased after incubating for 72 h at 10°C. The biofilm-forming capacity was the lowest after incubating for 24 h at 37°C. Due to the presence of resistance and virulence genes, multi-antimicrobial resistance, and biofilm-forming capacity, the results of this study suggest a risk to the public health as these pathogens are associated with foodborne diseases, which emphasizes the hazard of resistance gene propagation in the environment.

Detection ofSalmonellaTyphi andblaCTX-MGenes in Drinking Water, Wastewater, and Environmental Biofilms in Sindh Province, Pakistan

“…Environmental surveillance for S. Typhi and other fecal-oral pathogens is important for determining microbial epidemiology and providing data for risk assessments and prevention of pathogen spread; however, current environmental surveillance strategies traditionally restrict sampling to bulk water, which may miss biofilms as an important environmental reservoir of S. Typhi and blaCTX-M-15. S. Typhi has previously been found in environmental biofilms [14], and S. Typhi recovered from the environment has demonstrated biofilm-forming capability [21]. This is highly relevant to S. Typhi dissemination via drinking water, as distribution systems are common substrates for environmental biofilm development.…”

“…Typhi has previously been found in environmental biofilms [14], and S . Typhi recovered from the environment has demonstrated biofilm-forming capability [21]. This is highly relevant to S .…”