Fifteen-year surveillance of non-typhoidal Salmonella bloodstream infections in a tertiary care hospital in southern Türkiye

Abstract

Introduction: Nontyphoidal Salmonella (NTS) is an important cause of bloodstream infections (BSIs), particularly among individuals with comorbidities or immunosuppression. Long-term data on invasive NTS infections remain limited in many regions. This retrospective study aimed to describe the clinical characteristics, serotype distribution, antimicrobial resistance (AMR) patterns, and outcomes of NTS-BSIs in a tertiary care hospital in Antalya, Türkiye, between 2005 and 2019.

Methodology: Demographic and clinical data were obtained from hospital records. The isolates were identified using matrix-assisted laser desorption/ionization–time of flight (MALDI-TOF) mass spectrometry and serotyped at the National Public Health Laboratory. Antimicrobial susceptibility was determined by gradient diffusion. The results were interpreted according to the European Committee on Antimicrobial Susceptibility Testing clinical breakpoints.

Results: Of the 58 included patients (62.1% male; median age 42.8 years), 96.4% had at least one comorbidity; most commonly solid organ malignancies (21.4%). Salmonella Enteritidis was the predominant serotype (82.8%), followed by S. Infantis (3.4%). The cases were most frequent in autumn (41.4%). The rates of resistance were 29.3% for ampicillin, 13.7% for ciprofloxacin, and 1.8% for trimethoprim-sulfamethoxazole. All the isolates were susceptible to ceftriaxone and azithromycin, while 12.0% exhibited multidrug resistance. The overall mortality was 25% (14/56), with ampicillin resistance detected in 6 fatal cases.

Conclusions: This long-term single-center study demonstrates that S. Enteritidis is the leading cause of NTS BSIs in Antalya and is associated with seasonal clustering and notable AMR. The substantial burden of comorbidities and mortality underscores the importance of continued regional AMR surveillance and appropriate empirical treatment strategies.