Changing epidemiology and antimicrobial resistance of bacteria causing bacteremia in Taiwan: 2002-2020

Bacteremia is associated with significant morbidity and mortality. The emergence of bacteria with antimicrobial resistance (AMR) has further exacerbated the poor outcomes associated with bacteremia. The Taiwan Surveillance of Antimicrobial Resistance (TSAR) program was established in 1998 to monitor bacterial epidemiology and antimicrobial resistance trends across all patient types and age groups. Between 2002 and 2020, a total of 14,539 non-duplicate bacteremia isolates were collected biennially from 29 hospitals during the months of July-September as part of the TSAR program. The three most common bacteremia agents were Escherichia coli (31%), Staphylococcus aureus (13.6%), and Klebsiella pneumoniae (12.7%) overall. However, there was a steady increase in the proportions of E. coli and Enterococcus faecium isolated from bacteremia cases (both P < 0.001), while the proportions of Acinetobacter spp. decreased. Regarding antimicrobial resistance, there was a notable increase in rates of third-generation cephalosporin and fluoroquinolone non-susceptibility among E. coli and K. pneumoniae, while the rates of carbapenem non-susceptibility were elevated but remained milder in these two species, especially in E. coli. Of concern is the alarming increase in vancomycin resistance among E. faecium, rising from 10.0% in 2004 to 47.7% in 2020. In contrast, the prevalence of methicillin-resistant S. aureus has remained stable at 51.2% overall. In conclusion, E. coli, with increasing third-generation cephalosporin and fluoroquinolone resistance, is the predominant cause of bacteremia in Taiwan during the 18-year surveillance. The escalating proportion of E. faecium in bacteremia, coupled with a concurrent upsurge in vancomycin resistance, presents a therapeutic challenge in the recent decade.

AMR surveillance not only enables the identification of regional variations but also supports the development of coordinated efforts to combat AMR on a global scale. The TSAR has been a biennial, government-endorsed, multicenter study focusing on pathogens isolated from inpatients and outpatients in Taiwan hospitals since 1998. Our report presents an 18-year comprehensive analysis on blood isolates in the 2002-2020 TSAR program. The study highlights an alarming increase in the proportion of E. faecium causing bacteremia accompanied by elevated vancomycin resistance. It is worth noting that this trend differs from the observations in the United States and China. Understanding the composition of bacteria causing bacteremia, along with their prevalence of antimicrobial resistance, holds significant importance in establishing healthcare and research priorities. Additionally, this knowledge serves as a critical factor in evaluating the effectiveness of preventive interventions.