An epidemiological survey on the prevalence of Salmonella in swine in central Italy

The aim of the study was to evaluate the prevalence of Salmonella spp. in swine herds in Italy. Samples of faeces from finishing swine farms, cecal contents and ileo-cecal lymphnodes from pigs at slaughter were analysed for Salmonella. Samples of blood serum and meat juice were collected from the same groups, and tested for antibodies against Salmonella O-antigens with an ELISA test kit. 6.5% of faeces from finishing swine resulted positive, with 40% of the groups showing at least one positive sample, while Salmonella was isolated from 28.5% of cecal samples (85% of the groups) and 26.4% of lymph nodes (75% of the groups). The results of serology showed positivity in 100% of the herds and 95% of groups at slaughter. S. Typhimurium, S. Infantis, S. Derby were the most frequent isolated serotypes

Occurrence and temporal distribution of extended-spectrum β-lactamase-producing Escherichia coli in clams from the Central Adriatic, Italy

The spread of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is a major public health issue. Bivalves are filter-feeder animals capable of bioaccumulating the microorganisms present in water. This physiological characteristic makes them both good indicators of environmental contamination and possible carriers of pathogenic bacteria, including those resistant to antimicrobials. The aim of this study was to investigate the occurrence of ESBL-producing E. coli in clams (n = 308) collected from harvesting areas of the Central Adriatic Sea between 2018 and 2019. ESBL- /class C β-lactamase (AmpC)- producing E. coli and Escherichia spp. were isolated by streaking over the surface of MacConkey agar plates supplemented with cefotaxime enriched broths of the initial shellfish suspension. E. coli and Escherichia spp. resistant to cefotaxime were screened for ESBL production by using the double disk synergy test. Susceptibility to different antimicrobials and confirmation of ESBL-production were determined by the minimum inhibitory concentration (MIC) test. Isolates were further characterized by whole genome sequencing (WGS) and bioinformatic analysis of genomes with different tools. Overall, ESBL-producing E. coli were isolated from 3% of the samples. Of 13 ESBL- and ESBL−/AmpC-producing Escherichia spp. (n = 11 E. coli, n = 1 E. marmotae, n = 1 E. ruysiae) isolates, 13 were resistant to ampicillin and cefotaxime, 9 to sulfamethoxazole, 6 to tetracycline and nalidixic acid, 4 to trimethoprim, and 3 to ceftazidime, cefoxitin, ciprofloxacin, and chloramphenicol. Moreover, the majority (8/11) of the ESBL-producing E. coli isolates were multidrug-resistant. WGS showed that the isolates predominantly carried the blaCTX-M-15 gene (3/11) and blaCTX-M-14 and blaCTX-M-1 (2/11 each). The AmpC β-lactamase CMY-2 was found in two isolates. Phylogroup A was the most prevalent (5/11), followed by phylogroups D (4/11), F (1/11), and B2 (1/11). Ten different sequence types (STs) were identified. Occurrence at sampling sites ranged between 0 and 27%. To identify associations between the occurrence of ESBL-producing E. coli and E. coli levels, samples were divided into two groups, with E. coli at >230 MPN/100 g and E. coli at ≤230 MPN/100 g. ESBL-producing E. coli isolates were significantly more commonly recovered in samples with higher E. coli levels (14%) than in those with lower levels of E. coli (2%). Moreover, the majority (3/4) of the potentially pathogenic strains were isolated in samples with higher E. coli levels. These findings provided evidence for the bacterial indicator of fecal contamination, E. coli, as an index organism for ESBL-producing E. coli isolates in bivalves

An epidemiological survey on the prevalence of Salmonella in swine in central Italy

The aim of the study was to evaluate the prevalence of Salmonella spp. in swine herds in Italy. Samples of faeces from finishing swine farms, cecal contents and ileo-cecal lymphnodes from pigs at slaughter were analysed for Salmonella. Samples of blood serum and meat juice were collected from the same groups, and tested for antibodies against Salmonella O-antigens with an ELISA test kit. 6.5% of faeces from finishing swine resulted positive, with 40% of the groups showing at least one positive sample, while Salmonella was isolated from 28.5% of cecal samples (85% of the groups) and 26.4% of lymph nodes (75% of the groups). The results of serology showed positivity in 100% of the herds and 95% of groups at slaughter. S. Typhimurium, S. Infantis, S. Derby were the most frequent isolated serotypes.</p

Transport to the Slaughterhouse Affects the Salmonella Shedding and Modifies the Fecal Microbiota of Finishing Pigs

Contaminated pork is a significant source of foodborne Salmonellosis. Pork is contaminated at the slaughterhouse and the intestinal content is the predominant source of Salmonella for carcass contamination. The prevalence of Salmonella-positive pigs increases significantly when the time of transport to the slaughterhouse is longer than two hours. The hypothesis behind this study is that transport to the slaughterhouse increases the load of Salmonella in feces and determines a shift of the fecal microbiota in finishing pigs. Fecal samples were collected in a pig herd positive for Salmonella spp., the day before the transport and at the slaughterhouse. Salmonella loads were estimated by the most probable number (MPN) technique, according to the ISO/TS 6579-2:2012/A1. Moreover, the fecal bacteria composition was assessed by sequencing the V3-V4 hypervariable regions of the 16S rRNA gene. Our study showed that the load of Salmonella increases after transport, confirming that this phase of the production chain is a critical point for the control of Salmonella contamination. A lower richness and an increased beta-diversity characterized the fecal microbiota composition of Salmonella-positive animals after transport. In this stage, a natural Salmonella infection causes a disruption of the fecal microbiota as observed in challenge studies

Characterization of a prophage and a defective integrative conjugative element carrying the optrA gene in linezolid-resistant Streptococcus dysgalactiae subsp. equisimilis isolates from pigs, Italy

Objectives: To investigate the optrA-carrying genetic elements and their transferability in two linezolid-resistant Streptococcus dysgalactiae subsp. equisimilis (SDSE) strains of swine origin. Methods: SDSE strains (V220 and V1524) were phenotypically and genotypically characterized. Transferability of oxazolidinone resistance genes (filter mating), genetic elements and relatedness between isolates (WGS) were analysed. Excision of the genetic elements was assayed by inverse PCR. Results: SDSE isolates were resistant to chloramphenicol, florfenicol and linezolid, but susceptible to tedizolid and both carried the optrA gene.In SDSE V220 optrA was located on a 72.9-kb ICESdyV220 inserted in the 3' end of the chromosomal rum gene. It was 94%-96% identical (coverage, from 31% to 61%) to other optrA-carrying ICEs. In-depth ICESdyV220 sequence analysis revealed that optrA was carried by an IMESdyV220 (17.9 kb), also containing the tet(O/W/32/O) gene. Inverse PCR assays excluded the ICESdyV220 mobility. In SDSE V1524, optrA was carried by the ΦSdyV1524 prophage, integrated near the 5' end of the chromosomal had gene, showing a genetic organization similar to that of other streptococcal phage. Conjugation and transduction assays failed to demonstrate the optrA transferability to streptococcal recipients. V220 and V1524 belonged to two novel sequence types (ST704 and ST634, respectively). Conclusions: To the best of our knowledge, this is the first identification of the optrA gene on a prophage and an ICE in SDSE isolates from swine brain.These findings are consistent with the current belief in the key role of bacteriophages and ICEs in the streptococcal evolution and adaptation

Assessing the Load, Virulence and Antibiotic-Resistant Traits of ESBL/Ampc E. coli from Broilers Raised on Conventional, Antibiotic-Free, and Organic Farms

Poultry is the most likely source of livestock-associated Extended Spectrum Beta-Lactamase (ESBL) and plasmid-mediated AmpC (pAmpC)-producing E. coli (EC) for humans. We tested the hypothesis that farming methods have an impact on the load of ESBL/pAmpC-EC in the gut of broilers at slaughter. Isolates (n = 156) of antibiotic-free (AF), organic (O), and conventional (C) animals were characterized for antibiotic susceptibility and antibiotic resistance genes. Thirteen isolates were whole-genome sequenced. The average loads of ESBL/pAmpC-EC in cecal contents were 4.17 Log CFU/g for AF; 2.85 Log CFU/g for O; and 3.88 Log CFU/g for C type (p &lt; 0.001). ESBL/pAmpC-EC isolates showed resistance to antibiotic classes historically used in poultry, including penicillins, tetracyclines, quinolones, and sulfonamides. Isolates from O and AF farms harbored a lower proportion of resistance to antibiotics than isolates from C farms. Among the determinants for ESBL/pAmpC, CTX-M-1 prevailed (42.7%), followed by TEM-type (29%) and SHV (19.8%). Avian pathogenic E. coli (APEC), belonging to ST117 and ST349, were identified in the collection. These data confirm the possible role of a broiler as an ESBL/AmpC EC and APEC reservoir for humans. Overall, our study suggests that antibiotic-free and organic production may contribute to a reduced exposure to ESBL/AmpC EC for the consumer