Occurrence, genetic diversity and resistance profiles of Salmonella enterica from Brazilian sausages collected at production facilities.

This study aimed to investigate the occurrence and the genetic diversity of Salmonella enterica subsp. enterica in sausages from Southern Brazil, evaluate virulence genes and determine the phenotypic and genotypic basis of antimicrobial and sanitizer resistance. Salmonella was detected in sausage samples with an overall prevalence of 5.5%. The prevalent serovars were S. Infantis and S. Rissen. Pulsed-field gel electrophoresis (PFGE) analysis yielded nine distinct PFGE profiles, and some of them were recurrently recovered in the same establishment on different dates. Among tested isolates, 28.5% showed resistance to at least one antimicrobial agent and a multidrug-resistance (MDR) profile was observed in 21.4%. Resistance occurred most frequently to ampicillin, sulfonamide, trimethoprim/sulfamethoxazole, and trimethoprim. Regarding the genotypic antimicrobial resistance profile, S. Schwarzengrund carried tet(B), strA, strB, and sul2 genes. Benzalkonium chloride and chlorhexidine were more effective than peracetic acid and sodium hypochlorite, showing lower minimum inhibitory concentration values. Six Salmonella serovars were found, demonstrating a potential risk of salmonellosis associated with consuming this food. Salmonella carrying virulence genes, MDR profile, and tolerance to sanitizers is a public health concern and a challenge for the food industry, suggesting that new strategies should be developed to control this pathogen. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05809-w.

Virulence genes and sanitizers resistance in Salmonella isolates from eggs in southern Brazil.

Salmonella spp. causes foodborne diseases related to the consumption of contaminated foods, especially poultry products. This study aimed to investigate the occurrence of Salmonella spp. serovars in raw eggs from supermarkets and street food markets in southern Brazil, to analyze virulence genes, resistance profiling to antimicrobials and sanitizers, and to determine the susceptibility of the isolates to Butia odorata extract. Among 160 samples analyzed, just two (1.25%) were positive for Salmonella spp.. One positive sample was from egg yolk (S. enterica serovar Gallinarum, isolate S28), and another one was from eggshell (S. enterica serovar Panama, isolate S37). Regarding the virulence genes, the isolate S37 harbored all the genes evaluated (hilA, invA, spvC, sefA, and pefA), while the isolate S28 did not harbor the pefA gene. The isolate S28 was resistant to tobramycin, azithromycin, and trimethoprim, while the isolate S37 showed resistance profile just to nalidixic acid. However, none of the resistance genes evaluated were identified. Both isolates showed resistance to benzalkonium chloride, chlorhexidine digluconate, sodium hypochlorite, and peracetic acid, presenting high MIC values for these sanitizers. In contrast, B. odorata extract showed antimicrobial activity against the isolates S28 and S37, however, more studies are needed to prove its potential as a natural antimicrobial compound.

Biofilm-forming ability of poultry Campylobacter jejuni strains in the presence and absence of Pseudomonas aeruginosa.

The aims of this study were to evaluate the ability of Campylobacter jejuni isolated from a poultry slaughterhouse to form biofilm in the presence and absence of Pseudomonas aeruginosa, and the effect of surface (stainless steel, polystyrene), temperature (7, 25, and 42 °C), and oxygen concentration (microaerophilic and aerobic conditions) on the formation of biofilm. The genes ahpC, cadF, clpP, dnaJ, docA, flaA, flaB, katA, kpsM, luxS, racR, and sodB, related to biofilm formation by C. jejuni, were also investigated. All isolates formed biofilm on stainless steel and on polystyrene, in both aerobic and microaerophilic atmospheres, including temperatures not optimal for C. jejuni growth (7 and 25 °C), and biofilm also was formed in the presence of P. aeruginosa. In dual-species biofilm on stainless steel, biofilm formation was 2-6 log CFU·cm-2 higher at 7 °C for all isolates, in comparison with monospecies biofilm. Ten genes (ahpC, cadF, clpP, dnaJ, docA, flaA, flaB, luxS, racR, and sodB) were detected in all isolates, but katA and kpsM were found in four and six isolates, respectively. The results obtained are of concern because the poultry C. jejuni isolates form biofilm in different conditions, which is enhanced in the presence of other biofilm formers, such as P. aeruginosa.

Campylobacter jejuni isolated from poultry meat in Brazil: in silico analysis and genomic features of two strains with different phenotypes of antimicrobial susceptibility.

Campylobacter jejuni is the most common bacterial cause of foodborne diarrheal disease worldwide and is among the antimicrobial resistant "priority pathogens" that pose greatest threat to public health. The genomes of two C. jejuni isolated from poultry meat sold on the retail market in Southern Brazil phenotypically characterized as multidrug-resistant (CJ100) and susceptible (CJ104) were sequenced and analyzed by bioinformatic tools. The isolates CJ100 and CJ104 showed distinct multilocus sequence types (MLST). Comparative genomic analysis revealed a large number of single nucleotide polymorphisms, rearrangements, and inversions in both genomes, in addition to virulence factors, genomic islands, prophage sequences, and insertion sequences. A circular 103-kilobase megaplasmid carrying virulence factors was identified in the genome of CJ100, in addition to resistance mechanisms to aminoglycosides, beta-lactams, macrolides, quinolones, and tetracyclines. The molecular characterization of distinct phenotypes of foodborne C. jejuni and the discovery of a novel virulence megaplasmid provide useful data for pan-genome and large-scale studies to monitor the virulent C. jejuni in poultry meat is warranted.

Resistance to benzalkonium chloride and cadmium chloride in Listeria monocytogenes isolates from food and food-processing environments in southern Brazil.

Resistance to quaternary ammonium compounds such as benzalkonium chloride (BC) has been observed in many Listeria monocytogenes strains worldwide and is associated with cadmium chloride (CC) resistance. Therefore, the aims of this study were to evaluate the susceptibility to BC and CC, detect the presence of resistance genes, and investigate the possible role of efflux pumps in BC and CC resistance in L. monocytogenes isolates from food and food-processing environments in southern Brazil. All 50 L. monocytogenes isolates (100%) were resistant to BC, and 29 isolates (58%) were resistant to CC. According to the resistance genes (mdrL, lde, emrE, bcrABC, radC, qacA, qacC/D, qacH, qacEΔ1, cadA1, cadA2, cadA3, cadA4, and cadC), only the efflux pumps MdrL and Lde were identified in 12 (24%) and 33 (66%) isolates, respectively. The analysis of resistance to BC and CC in the presence of reserpine, an efflux pump inhibitor, showed that the resistance was not influenced by efflux pumps. This study confirmed a high profile of resistance to BC and CC in L. monocytogenes from food sources, and to the knowledge of the authors, this is the first report of the presence of efflux pumps MdrL and Lde in L. monocytogenes from Brazil.

Presence of genes associated with adhesion, invasion, and toxin production in Campylobacter jejuni isolates and effect of temperature on their expression.

The aims of this study were to evaluate the presence of genes associated with adhesion (cadF), invasion (ciaB), and cytotoxin production (cdtA, cdtB, and cdtC) among Campylobacter jejuni isolates from a poultry slaughterhouse and to investigate the effect of different temperatures on the expression of these virulence-associated genes. A total of 88 C. jejuni isolates from cecum, liver, chicken carcasses, chilled water, and scalding water were submitted to PCR assay for detection of virulence genes. Representative isolates were selected for gene expression evaluation at 37 and 42 °C, according to their virulence gene profile and genotypic typing. All C. jejuni isolates carried the five virulence-associated genes, which play an important role in the infectious process. Differential gene expression by RT-qPCR was observed among C. jejuni isolates at 37 and 42 °C. The expression levels at 37 °C showed upregulation of the ciaB, cdtA, cdtB, and cdtC genes in five isolates, with the exception of ciaB for isolate 4. At 42 °C, upregulation was observed for ciaB and cdtC, cdtA and cdtB, and cadF in four, three, and two isolates, respectively. The C. jejuni isolates expressed the virulence genes evaluated, and the expression is gene- and isolate-dependent and varied according the temperature.

Isolation of Enterococcus faecium, characterization of its antimicrobial metabolites and viability in probiotic Minas Frescal cheese.

The aim of this study was to isolate Enterococcus faecium from raw milk samples, to characterize its antimicrobial metabolites, and to evaluate its viability in a probiotic Minas Frescal cheese. For this, antagonist activity against Listeria monocytogenes, safety aspects and biochemical, genotypic, and probiotic characteristics of the isolates were evaluated. Minas Frescal cheese was manufactured with the isolate that showed the best characteristics in vitro, and its viability in the product was evaluated. It was observed that of the 478 lactic acid bacteria isolates, only isolate E297 presented antagonist activity, genes encoding for enterocin production and absence of virulence factors. Besides that, E297 presented probiotic characteristics in vitro, and maintained its viability (8.09 log CFU mL-1) for 14 days of cold storage, when it was added to cheese. Therefore, isolate E297 can be considered a promising microorganism for the manufacture of probiotic foods, especially Minas Frescal cheese.

Butia odorata Barb. Rodr. extract inhibiting the growth of Escherichia coli in sliced mozzarella cheese.

The aims of this study were to verify the occurrence of Escherichia coli in sliced mozzarella cheese marketed in Pelotas city, Brazil and perform the phenotypic and genotypic characterization of the isolates. Besides that, evaluate the susceptibility of E. coli to Butia odorata extract, characterize it chemically, and apply the extract in sliced mozzarella cheese contaminated experimentally with E. coli. Escherichia coli was isolated in 5% (4/80) of cheese samples, but no gene used as marker for E. coli O157:H7 or virulence genes were detected. The isolates were susceptible to B. odorata extract (MIC 15 mg mL-1 and MBC 29-58 mg mL-1), and the major compounds present in the extract were Z-10-Pentadecenol (80.1%) and Palmitic acid (19.4%). In cheese, after 72 h there was a significant difference between control (2.8 log CFU cm-2) and treated samples with MIC, 2 × MIC, 4 × MIC and 8 × MIC (1.3, 1.4, 1.6 and 0.5 log CFU cm-2, respectively). The isolation of E. coli in cheese indicates fecal contamination and poor hygienic practices. Butia odorata extract showed antimicrobial activity against E. coli both in vitro and in situ, indicating that it can be a good alternative for inhibiting the growth of this microorganism in sliced cheese.

Occurrence and characterization of Listeria monocytogenes from beef jerky processing line.

Beef jerky is a ready-to-eat product that does not require refrigeration at the point of sale. Here, we evaluated the occurrence of Listeria monocytogenes in the production process of beef jerky, the presence of virulence genes and the genomic relatedness of the isolates, to assess the safety of the final product. The raw material, surfaces with and without contact with the product and the final product were evaluated along the beef jerky processing line. The samples were evaluated by VIDAS immunoassay system, and the L. monocytogenes isolates were confirmed and evaluated for the presence of several virulence genes by PCR. Listeria monocytogenes was identified in six of the 84 samples (7.14%), and no genetic relationship was observed among isolates. Samples of raw material (2/7), food contact surface (1/56), and work surfaces without contact with food (3/14) presented contamination by L. monocytogenes. The final product was not contaminated, demonstrating that barriers to multiplication of pathogens used during the production process were effective for its control.

First report of the Staphylococcus aureus isolate from subclinical bovine mastitis in the South of Brazil harboring resistance gene dfrG and transposon family Tn916-1545.

The aim of this work was to identify at the molecular level the species of coagulase-positive staphylococci isolates from clinical and subclinical bovine mastitis samples in Southern Brazil, and to evaluate the antimicrobial resistance profile, as well as the presence of resistance genes. According to the PCR assay, all 31 isolates were classified as Staphylococcus aureus. The isolates were tested for resistance to penicillin, ampicillin, oxacillin, cefoxitin, cephalothin, ceftiofur, streptomycin, tobramycin, teicoplanin, erythromycin, clindamycin, enrofloxacin, sulfonamide, trimethoprim-sulfamethoxazole, trimethoprim, and tetracycline by the disk diffusion method. Most of the isolates were resistant to sulfonamide (20), followed by ampicillin and clindamycin (16). Twenty isolates were multidrug-resistant. PCR was used for the detection of several antimicrobial resistance genes (ereB, ermB, ermC, tetA, tetB, tetK, tetL, tetM, tetO, Tn916-1545, strA, strB, sul1, sul2, dfrA, dfrG, dfrK, blaZ, mecA, and mecC). The most prevalent antimicrobial resistance genes were tetK and tetL, ereB, followed by tetM, Tn916-1545 and blaZ, detected in 11, nine and four isolates, respectively. For all the tetM gene positive isolates, the presence of conjugative transposons of the Tn916-1545 family was detected. The presence of multidrug-resistant isolates, antimicrobial resistance genes and transposons suggests a potential risk of spreading multi-resistance genes to other bacteria.

Prevalence and expression of staphylococcal enterotoxin genes in Staphylococcus aureus isolated from food poisoning outbreaks.

Staphylococcus aureus is an important pathogen of foodborne origin. The pathogen produces a variety of toxins that include the staphylococcal enterotoxins (SE). The present study aimed to evaluate the prevalence and expression of 5 SE genes (sea, seb, sec, sed, and see) in S. aureus isolated from outbreaks occurred in the state of Rio Grande do Sul, Brazil. All isolates, with the exception of 2, presented the same or higher transcriptional expression than the reference strains for at least 1 of these genes. The presence of SE genes combined with high levels of transcriptional expression suggests that 1 or more SEs were involved with the staphylococcal food poisoning outbreak analyzed in the present study.

Antibacterial activity of Timsen® (n-alkyl dimethyl benzyl ammonium chloride-40%) in scalding and precooling water in poultry slaughterhouses.

The objective of this study was to evaluate the efficacy of a product based on n-alkyl dimethyl benzyl ammonium chloride-40%, marketed as Timsen®, during scalding and precooling of poultry carcasses in slaughterhouses. To this end, three poultry slaughterhouses (A, B and C) were evaluated. The product was added (200 ppm) to the scalding (58 °C) and precooling water (4 °C), and microbiological analyses were performed of the water and the poultry carcasses before and after Timsen® addition. The product controlled the multiplication of aerobic mesophilic microorganisms, both in the scalding as in the precooling water. In a comparison of carcasses soaked in Timsen®-treated scalding and precooling water with carcasses soaked in untreated water, the count of aerobic mesophilic microorganisms in the later was higher and thermotolerant coliform was not detected in samples of carcasses soaked in Timsen®-treated water. When the scalding and precooling water was not treated with the product, Listeria spp. was isolated from poultry carcasses of two slaughterhouses (A and C), while these microorganisms were not detected when Timsen® was applied. The use of Timsen® in the scalding and precooling water enhanced the safety and control microbial contamination of poultry carcasses.

Staphylococcus aureus isolated from handmade sweets: Biofilm formation, enterotoxigenicity and antimicrobial resistance.

Staphylococcus aureus is the second most important pathogen involved in foodborne outbreaks in Brazil. Because of their widespread distribution and biofilm forming ability, handmade sweets are easily contaminated with S. aureus. The aim of this study was to isolate and identify coagulase-positive staphylococci (CPS) from handmade sweets produced in Pelotas City/Brazil. The virulence potential was checked by evaluating the presence of the staphylococcal enterotoxin genes, icaA and icaD genes, the biofilm forming potential and antimicrobial resistance of the isolates. It was find just S. aureus among the CPS isolates. All the S. aureus isolates had biofilm forming ability on stainless steel and more than half of them on polystyrene surfaces. The majority of the isolates carried the icaA (66.6%) and icaD (58.4%) genes and some of them had the genes encoding enterotoxins A (33.4%) and B (16.6%). Furthermore, the majority of the isolates (83%) were resistant to at least one of the tested antimicrobials and multidrug resistance was observed in 8.4% of the isolates. The isolates had virulence potential, and half of them were enterotoxigenic. In addition, the ability of all the isolates to produce biofilms highlights the danger posed by these potentially virulent microorganisms persisting in food manufacturing environments.

Biofilm formation by Listeria monocytogenes from the meat processing industry environment and the use of different combinations of detergents, sanitizers, and UV-A radiation to control this microorganism in planktonic and sessile forms.

This study aimed to evaluate the ability of biofilm formation by L. monocytogenes from the meat processing industry environment, as well as the use of different combinations of detergents, sanitizers, and UV-A radiation in the control of this microorganism in the planktonic and sessile forms. Four L. monocytogenes isolates were evaluated and showed moderate ability to form biofilm, as well as carried genes related to biofilm production (agrB, agrD, prfA, actA, cheA, cheY, flaA, sigB), and genes related to tolerance to sanitizers (lde and qacH). The biofilm-forming isolates of L. monocytogenes were susceptible to quaternary ammonium compound (QAC) and peracetic acid (PA) in planktonic form, with minimum inhibitory concentrations of 125 and 75 ppm, respectively, for contact times of 10 and 5 min. These concentrations are lower than those recommended by the manufacturers, which are at least 200 and 300 ppm for QAC and PA, respectively. Biofilms of L. monocytogenes formed from a pool of isolates on stainless steel and polyurethane coupons were subjected to 14 treatments involving acid and enzymatic detergents, QAC and PA sanitizers, and UV-A radiation at varying concentrations and contact times. All treatments reduced L. monocytogenes counts in the biofilm, indicating that the tested detergents, sanitizers, and UV-A radiation exhibited antimicrobial activity against biofilms on both surface types. Notably, the biofilm formed on polyurethane showed greater tolerance to the evaluated compounds than the biofilm on stainless steel, likely due to the material's surface facilitating faster microbial colonization and the development of a more complex structure, as observed by scanning electron microscopy. Listeria monocytogenes isolates from the meat processing industry carry genes associated with biofilm production and can form biofilms on both stainless steel and polyurethane surfaces, which may contribute to their persistence within meat processing lines. Despite carrying sanitizer tolerance genes, QAC and PA effectively controlled these microorganisms in their planktonic form. However, combinations of detergent (AC and ENZ) with sanitizers (QAC and PA) at minimum concentrations of 125 ppm and 300 ppm, respectively, were the most effective.

Antagonistic activity of Lactobacillus spp. and Bifidobacterium spp. against cariogenic Streptococcus mutans in vitro and viability when added to chewing gum during storage.

The aim of the work was to evaluate antagonistic activity of Lactobacillus spp. and Bifidobacterium spp. in vitro against cariogenic Streptococcus mutans UA 159 and viability in chewing gum, during storage. Antagonistic activity was evaluated in vitro by the "spot on the lawn" test. Two bacteria were chosen and subjected to lyophilization and microencapsulation using the atomization method, containing polyvinylpyrrolidone polymer and lactose as encapsulating agents. For application in food matrices, four treatments were elaborated: chewing gum containing lyophilized B. lactis B94 (BLL), microencapsulated B. lactis B94 (BLE), lyophilized L. brevis (LBL), and microencapsulated L. brevis (LBE). Both microorganisms demonstrated a high capacity for inhibition against S. mutans, when compared to oral antiseptic chlorhexidine 0.2% in vitro, and according to the test of sensitivity profile to proteolytic enzymes, all the bacteria tested are producers of antimicrobial peptides, resulting in the inhibitory activity of the cariogenic bacterium. Furthermore, the viability of B. lactis B94 and L. brevis was maintained after microencapsulation, indicating that the process was efficient, with no significant difference (p < 0.05) between the results. And, in the chewing gum containing the bacteria during the storage period (33 days), it was found that cell immobilization did not significantly influence (p < 0.05) the counts of L. brevis but benefited the viability of B. lactis B94. Therefore, both probiotic bacteria are producers of antimicrobial substances with the ability to inhibit S. mutans, in vitro. The microencapsulation was considered efficient since it influenced the viability of B. lactis B94 (> 8 log CFU/g); however, the microencapsulation did not influence the viability of L. brevis since in both lyophilized and encapsulated form; the concentration of the bacteria remained above 8 log CFU/g during the storage period of the chewing gum.

Development of a microencapsulated probiotic delivery system with whey, xanthan, and pectin.

Pediococcus pentosaceus is a lactic acid bacterium that has probiotic potential proven by studies. However, its viability can be affected by adverse conditions such as storage, heat stress, and even gastrointestinal passage. Thus, the aim of the present study was to microencapsulate and characterize microcapsules obtained by spray drying and produced only with whey powder (W) or whey powder combined with pectin (WP) or xanthan (WX) in the protection of P. pentosaceus P107. In the storage test at temperatures of - 20 °C and 4 °C, the most viable microcapsule was WP (whey powder and pectin), although WX (whey powder and xanthan) presented better stability at 25 °C. In addition, WX did not show stability to ensure probiotic potential (< 6 Log CFU mL-1) for 110 days and the microcapsule W (whey powder) maintained probiotic viability at the three temperatures (- 20 °C, 4 °C, and 25 °C) for 180 days. In the exposition to simulated gastrointestinal juice, the WX microcapsule showed the best results in all tested conditions, presenting high cellular viability. For the thermal resistance test, WP microcapsule was shown to be efficient in the protection of P. pentosaceus P107 cells. The Fourier transform infrared spectroscopy (FTIR) results showed that there was no chemical interaction between microcapsules of whey powder combined with xanthan or pectin. The three microcapsules produced were able to protect the cell viability of the microorganism, as well as the drying parameters were adequate for the microcapsules produced in this study.

Beneficial effects of Lactococcus lactis subsp. cremoris LL95 treatment in an LPS-induced depression-like model in mice.

Clinical evidence suggests that neuroinflammation, activation of the immune system, and the composition of the intestinal microbiota are involved in the pathology of depression. This study evaluated the effectiveness of a probiotic intervention using Lactococcus lactis subsp. cremoris LL95 in ameliorating mood disorders in a lipopolysaccharide (LPS)-induced depression-like mouse model. C57BL/6 mice were randomly divided into four groups and treated with 5 mg/kg LPS via intraperitoneal injection to induce depression-like symptoms, followed by oral administration of LL95 for one week (1â€¯× 109 CFU/mouse). The animals were then subjected to a series of behavioral assessments, including open field, sucrose preference, and forced swimming tests. In addition, we evaluated the levels of reactive oxygen species, tumor necrosis factor-α, and interleukin-1ß in the hippocampal tissues of these animals, and also determined their fecal lactic acid bacteria (LAB) content. LL95 intervention improved LPS-induced depression-like behaviors in mice, including decreased sucrose preference and increased immobility time in the forced swim test. LL95 treatment reversed the LPS-induced increase in hippocampal levels of reactive oxygen species and tumor necrosis factor-α, and of interleukin-1ß to a lesser extent. Furthermore, LL95 intervention increased the fecal LAB content in these animals, suggesting changes in the gut microbiota. These findings suggest that LL95 exerts antidepressant-like effects in LPS-induced depression, which may be attributed to modulation of the oxidative status and pro-inflammatory cytokine expression in the hippocampus and alteration in the LAB content of the gut microbiota.

Survival of Microencapsulated Lactococcus lactis Subsp. lactis R7 Applied in Different Food Matrices.

Survival of Lactococcus lactis subsp. lactis R7, microencapsulated with whey and inulin, was analyzed when added to blueberry juice, milk, and cream. For 28 days, cell viability was evaluated for storage (4 °C), simulated gastrointestinal tract (GIT), and thermal resistance. All matrices demonstrated high cell concentration when submitted to GIT (11.74 and 12 log CFU mL-1), except for the blueberry juice. The thermal resistance analysis proved the need for microencapsulation, regardless of the food matrix. The results indicate that L. lactis R7 microcapsules have potential for application in different matrices and development of new probiotic products by thermal processing.

Genetic Profiles and Invasion Ability of Listeria monocytogenes Isolated from Bovine Carcasses in Southern Brazil.

ABSTRACT: The goals of this study were to evaluate the persistence and the virulence potential of Listeria monocytogenes isolated from beef carcasses obtained in processing facilities in the southern region of Rio Grande do Sul, Brazil, based on pulsed-field gel electrophoresis (PFGE), invasion ability in human colorectal carcinoma cells (HCT-116), internalin A (InlA) expression by Western blot, and identification of mutation points in inlA. PFGE profiles demonstrated that L. monocytogenes isolates were grouped based on their previously identified lineages and serogroups (lineage I: serogroup IIb, n = 2, and serogroup IVb, n = 5; lineage II: serogroup IIc, n = 5). Isolates with indistinguishable genetic profiles through this method were obtained from different slaughterhouses and sampling steps, with as much as a 3-year interval. Seven isolates showed high invasion ability (2.4 to 7.4%; lineage I, n = 6, and lineage II, n = 1) in HCT and expressed InlA. Five isolates showed low cell invasion ability (0.6 to 1.4%; lineage I, n = 1, and lineage II, n = 4) and did not express InlA, and two of them (lineage II, serogroup IIc) presented mutations in inlA that led to premature stop codon type 19 at position 326 (GAA → TAA). The results demonstrated that most L. monocytogenes isolates from lineage I expressed InlA and were the most invasive in HCT, indicating their high virulence potential, whereas most isolates from lineage II showed attenuated invasion because of nonexpression of InlA or the presence of premature stop codon type 19 in inlA. The obtained results demonstrated that L. monocytogenes with indistinguishable PFGE profiles can persist or be reintroduced in beef processing facilities in the studied region and that differences in their virulence potential are based on their lineages and serogroups.

Residues of Veterinary Drugs in Animal Products Commercialized in the Border Region of Brazil, Argentina, and Uruguay.

ABSTRACT: The traffic in international animal products can become a public health hazard when legal import sanitary procedures are not followed. In Brazil, due to its extensive border area, the importation of animal products is a common practice in many areas, especially in Rio Grande do Sul, a state that borders Argentina and Uruguay. The objective of this study was to evaluate the presence of veterinary drug residues (antibiotics and antiparasitics) in animal products consumed in Rio Grande do Sul. The presence of residues of veterinary antibiotics and antiparasitics was assessed in 189 meat (beef, pork, and chicken), processed dairy, and meat product samples bought in Argentina (n = 90) and Uruguay (n = 99). Residues of these veterinary drugs were detected in 50 (26.45%) of the samples; 28 samples (14.81%) had antibiotic residues, and 22 samples (11.64%) had antiparasitic residues. Of the 50 positive samples, 40% (15 from Argentina and 5 from Uruguay) had residues above the maximum residue limits (MRLs). Of these 20 samples, 12 had antiparasitic residues above the MRLs (11 beef samples had ivermectin and 1 pork sample had ivermectin and doramectin) and 8 had antibiotic residues above the MRLs (2 pork and 2 sausage samples had doxycycline, 2 cheese samples had doxycycline and chlortetracycline, 1 poultry meat sample had chloramphenicol, and 1 cheese sample had monensin). Because of the potential toxic effects on humans and the potential for pathogens to develop antibiotic resistance, the presence of these residues above the MRLs is a potential risk to public health. The negative impact of consumption of imported animal products can be reduced by implementation of an effective surveillance system and educational campaigns for the general population.