A case of staphylococcal food poisoning was observed in two individuals of the same family after consumption of primosale, a semiripened sheep cheese produced in Sicily. Staphylococcus aureus isolated from the cheese produced enterotoxin C (SEC) and carried both the enterotoxin C (sec) and the toxic shock syndrome toxin (tsst-1) gene. Following this case, an extensive survey was conducted on 971 food samples (raw milk, cheese, meat, and food preparations). S. aureus was detected in 102 of 971 food samples, from all types of food with the exception of ricotta cheese. The tsst-1 gene was present in 42% of the strains, either alone or in combination with other toxin genes. The enterotoxin C gene was the most represented enterotoxin, but it was only found in dairy products. Six S. aureus isolates carried the sea gene alone, two isolates carried both sea and seb, and one isolate carried both sea and sec. A significant percentage (46%) of all isolates carried a toxin gene, creating significant concern that virulent S. aureus can be transmitted through food in Sicily.
Staphylococcus aureus is the major cause of foodborne diseases worldwide. In this retrospective study, 84 S. aureus strains were characterized. The collection comprises 78 strains isolated during 1998 and 2014 from dairy products and tissue samples from livestock bred for dairy production in Sicily. One isolate was obtained from a pet (dog), one from an exotic animal (a circus elephant), and four human isolates were obtained during a severe food poisoning outbreak that occurred in Sicily in 2015. All the strains were characterized by pulsed-field gel electrophoresis (PFGE), for antibiotic resistance and presence of toxin genes. PFGE results showed 10 different pulsotypes, with three relatively frequent and three unique. The antibiotic resistance profiling showed that penicillin G (35.7%) and tetracycline (20.2%) resistance is largely spread. Most isolates contained at least one toxin gene making them a potential threat for public health. Enterotoxin sec gene was observed in 28.6% and seg in 23.8% of the strains, respectively; the human isolates were the only ones to concurrently harbor both seg and sei genes. In addition, 24 isolates were randomly selected and analyzed by multilocus sequence typing. Interestingly, the analysis showed the presence of 12 sequence types (STs), of which 6 were novel. One of them, ST700, was detected in 29% of the isolates and was found to be spread throughout Sicily. ST700 has been present in the island for almost 16 years (1998–2014) and it shows no host preference since it was isolated from different ruminant species. Four human isolates shared both the pulsotype (PT10) and the sequence type (ST9), as well as the virulence genes (seg-sei); this observation suggests that the isolates originated from a single clone, although they were obtained from two different individuals.
The prevalence of Salmonella infection was determined in a group of spur-thighed tortoises (Testudo graeca) seized during two smuggling attempts and in a population of captive Hermann's tortoises (Testudo hermanni) sheltered in a wildlife rescue centre. Salmonella spp. was isolated in 81 of 220 (36.8%) and in 17 of 67 (25.4%) cloacal swabs collected from the T. graeca and T. hermanni tortoises respectively. Overall, a total of 21 different Salmonella serotypes were found. Some of these serotypes are common to terrestrial chelonians while others have never been reported. All cultured serotypes were non-typhoidal but nonetheless many of these have been previously reported as source of human outbreaks of reptile-related salmonellosis. Eighty-two per cent and 5.3% of the isolates were resistant to two and three anti-microbial agents respectively. However, the isolates were highly susceptible to the anti-microbials of choice for the treatment of salmonellosis such as cephalosporins and fluoroquinolones. Our findings confirm that tortoises can be considered a reservoir for Salmonella and that care should be employed when handling and breeding these animals. Tight surveillance should be enforced to avoid illegal importation and prevent the trading of live tortoises, carriers of zoonotic pathogens.
The study summarises the results obtained over the period 2002-2013 by the Italian IT-Enter-Vet network, aimed at collecting data on isolates from non-human sources. A total of 42,491 isolates were reported with a progressive decrease over the years. Typhimurium was the most frequent serovar up to 2011, but then, it was overtaken by 4,[5],12,:i:-, Derby Livingstone and Enteritidis alternated as the third most commonly isolated serovars. With regard to the sources of isolation, Typhimurium was distributed ubiquitously among the animal species. On the contrary, 4,[5],12,:i:- and Derby were strictly associated with pigs, whereas Livingstone Enteritidis and Infantis were clearly related to poultry. Intriguingly, when the frequency of serovar distribution along the food chain was considered, it was evident that Typhimurium and Derby tended to persist along the chain, as they were isolated even more frequently from foods than from animals. A similar distribution was found for Enteritidis and Hadar. Despite limitations related to non-mandatory participation of laboratories in the network, the data presented are valuable to obtain a picture of the evolution of from non-human sources over time in Italy.
Salmonella spp. are among the most frequent causes of foodborne diseases, and the increasing occurrence of MDR strains is an additional cause for concern. In the three-year period 2019–2021, we collected Salmonella spp. strains isolated from different food categories analysed in the context of Regulation (EC) No 2073/2005 in order to assess their antibiotic susceptibility profiles and ESBL production. To determine the susceptibility profiles and identify MDR strains, we used the Kirby–Bauer method to test 17 antibiotics. Double-disc and PCR testing then allowed us to assess the production of ESBLs and the presence of beta-lactamase resistance genes. Phenotypic tests showed that 36 out of 67 strains were MDR and 52.7% of these were ESBL producers. Finally, molecular investigations conducted on ESBL-producing strains revealed the presence of blaSHV, blaCTX-M and blaTEM genes. Our results confirmed the prevalence of S. Infantis, an MDR strain and ESBL producer, in chicken meat. This suggests that further research on the prevalence of antibiotic resistance genes (ARGs) in foodborne strains is needed, especially from a One Health perspective.
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