Antibiotic-Resistant Salmonella Circulation in the Human Population in Campania Region (2010-2023)

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.