The continuous collection and analysis of updated data on the antimicrobic resistance among bacterial strains represent the essential core for the surveillance of this problem. The present work aimed to investigate the occurrence of antimicrobial resistance among Salmonella serovars isolated in foods in 2015–2019. A total of 178 Salmonella strains belonging to 39 serovars were tested against 10 antimicrobials. High proportions of Salmonella isolates were resistant to tetracycline (n = 53.9%), ciprofloxacin (n = 47.2%), ampicillin (n = 44.4%), nalidixic acid (n = 42.7%), and trimethoprim-sulfamethoxazole (n = 38.8%). Different resistance rates were recorded among the different serotypes of Salmonella, and S. Infantis, exhibited the highest resistance to antibiotics. A high percentage of strains isolated from poultry, pork, and bovine were resistant to at least one or two antimicrobials. Resistant and multidrug-resistant (MDR) strains were also recorded among the isolates from molluscan shellfish; however, the occurrence of resistant Salmonella strains isolated from this source was significantly lower compared with those reported for poultry, pork, and bovine. The high levels of resistance reported in the present study indicate a potential public health risk. Consequently, additional hygiene and antibiotic stewardship practices should be considered for the food industry to prevent the prevalence of Salmonella in foods.

Salmonellosis in water buffalo (Bubalus bubalis) calves is a widespread disease characterized by severe gastrointestinal lesions, profuse diarrhea and severe dehydration, occasionally exhibiting a systemic course. Several Salmonella serovars seem to be able to infect water buffalo, but Salmonella isolates collected from this animal species have been poorly characterized. In the present study, the prevalence of Salmonella spp. in water buffalo calves affected by lethal gastroenteritis was assessed, and a polyphasic characterization of isolated strains of S. Typhimurium was performed.

Wild animals are potential vectors of antibiotic-resistant bacteria in the environment. The present study aimed to investigate the occurrence of antimicrobial resistance among Salmonella serovars isolated from wildlife and the environment in Italy. A total of 164 Salmonella isolates were analyzed, and six different subspecies and 64 serovars were detected. High proportions of Salmonella isolates proved resistant to streptomycin (34.1%), followed by trimethoprim-sulfamethoxazole (23.2%), tetracycline (17.7%), ciprofloxacin (14.63%) and ampicillin (11.59%). By source, the lowest level of resistance was observed in Salmonella serovars isolated from a water environment, while antimicrobial resistance was frequent in strains collected from shellfish, reptiles and birds. Multidrug-resistant strains were recovered from seafood (n = 11), mammals (n = 3) and water (n = 1). Three S. Typhimurium monophasic variant strains showed asimultaneous resistance to ampicillin, streptomycin, tetracycline and trimethoprim-sulfamethoxazole, which represents a recognized alert resistance profile for this serovar. These data indicate the environmental dissemination of resistant strains due to anthropogenic activities, which, in southern Italy, probably have a higher impact on marine ecosystems than on terrestrial ones. Moreover, as most of the animals considered in the present study are usually consumed by humans, the presence of resistant bacteria in them is a matter of great concern.

Background/Objectives: A retrospective study was conducted to evaluate antibiotic resistance among Salmonella strains isolated during human infection using data from the computer database (SIGLA) of the Salmonella Typing Center (Ce.Ti.Sa) of the Istituto Zooprofilattico del Mezzogiorno (IZSM). Methods: From 2010 to 2023, the Ce.Ti.Sa laboratory tested 680 Salmonella strains against the following: amoxicillin/clavulanic acid, ampicillin, azithromycin, cefixime, cefoxitin, cefotaxime, ceftazidime, chloramphenicol, ciprofloxacin, colistin, erythromycin, gentamicin, kanamycin, meropenem, nalidixic acid, pefloxacin, streptomycin, sulfisoxazole, sulfonamides, tetracyclines, tigecycline, and trimethoprim. Results: The most common serovars were S. monophasic Typhimurium (23.2%), S. Enteritidis (16.8%), and S. Typhimurium (16.0%). Nearly all strains were resistant to azithromycin (99.4%) and showed high resistance to sulphonamides, tetracycline, streptomycin, and ampicillin. The study found that 45.8% of strains exhibited multidrug resistance. Resistance to ciprofloxacin increased over time. Serovar-specific resistance varied: S. monophasic Typhimurium was resistant to azithromycin (100.0%), tetracycline (93.0%), and ampicillin (92.4%); S. Enteritidis showed 100.0% resistance to azithromycin; S. Typhimurium had high resistance to azithromycin, streptomycin, and ampicillin; and S. Infantis was resistant to erythromycin, sulfonamides, and azithromycin. Conclusions: The study highlights a troubling prevalence of Salmonella-resistant strains, emphasizing the need for infection prevention, proper antibiotic use in humans and animals, and the development of new antibiotics.

This case report describes for the first-time cases of severe gastroenteritis in water buffalo calves due to a new serovar of Salmonella enterica. The study was carried out on fecal matrix collected from live water buffalo calves that showed profuse diarrhea, severe dehydration and fever, exhibiting a systemic course. Culture and molecular investigations identified the pathogens isolated from intestinal contents as two Salmonella serovars, Salmonella enterica enterica O:35 and a new serovar of Salmonella enterica. The isolates showed multi-drug resistance. Timely diagnosis associated with a targeted antimicrobial treatment were found to be sufficient for the survival and recovery of the infected animals. Herd vaccines prepared from isolated pathogens were used to prevent further deaths of the calves.