132. Epidemiology, Antimicrobial Resistance and Predictors of Typhoidal and Non-Typhoidal Salmonella Bacteremia in Victoria, Australia

Abstract

BackgroundSalmonella species are major contributors to the global burden of foodborne disease. While typhoidal salmonella (TS) is typically associated with travel in high-income settings, non-typhoidal salmonella (NTS) is more commonly associated with locally acquired diarrhoeal disease. We aimed to assess the epidemiology, antimicrobial resistance (AMR) patterns, and clinical markers of Salmonella bloodstream infections (BSI) in Victoria, Australia.MethodsWe conducted a retrospective audit of blood culture results over a 5.5-year period at a large, private pathology provider, in Victoria, Australia. All Salmonella isolates detected in blood between January 2013 and June 2018 were included. Epidemiological, microbiological, AMR and clinical data were extracted from the pathology record and collated for analysis.ResultsOf 27,546 positive blood cultures, 262 were positive for Salmonella spp. (rate 9.51 per 1,000 positive cultures) in 187 episodes. 113 (60%) were NTS (47.8% S. Typhimurium, 9.7% S. Enteritidis), while 74 (40%) were TS (59% S. Typhi, 41% S. Paratyphi). Patients with TS were younger (median age 29 vs. 65, P < 0.0001), more likely to have traveled [OR 125 (95% CI 28.47, 549], but fewer had a positive stool [OR 0.21 (95% CI 0.08–0.58)] than those with NTS. NTS was associated with a higher median CRP (149 vs. 83, P < 0.001) and more frequently associated with an abnormal white cell count (39% vs. 18%, P = 0.003). Quinolone non-susceptibility was stable with time, and occurred more frequently in TS than NTS (71 vs. 23%, P < 0.0001). Non-susceptibility to Azithromycin was also common in TS (42%), and increasing with time (P = 0.02). Non-susceptibility to ≥1 antibiotic occurred in 54 (73%) of TS, while 24 (32%) had non-susceptibility ≥2. Ceftriaxone resistance occurred infrequently in both NTS and TS (2 vs. 0%, P = 0.5).ConclusionSalmonella is an uncommon cause of BSI in our setting, with similar proportions of TS and NTS. Typhoidal isolates were more likely to be associated with travel, and antimicrobial resistance. Despite this, ceftriaxone remains a reliable option for first-line therapy for both TS and NTS. Quinolone resistance remains common, while Azithromycin resistance has increased with time in TS.Disclosures All authors: No reported disclosures.