Epidemiology, Temporal Trends and Resistance Patterns of ESBL-Producing Non-Typhoidal Salmonella Isolated from Blood Cultures in Kisantu, DRC (2019-2022).

Background

Antimicrobial resistance (AMR), particularly due to extended-spectrum beta-lactamases (ESBL), is a growing threat to public health in sub-Saharan Africa. This study investigates the prevalence, epidemiological characteristics, resistance patterns and resistance dynamic over time of ESBL-producing non-typhoidal Salmonella (NTS) bacteremia in Kisantu, Democratic Republic of Congo (DRC), from 2019 to 2022.

Methods

A retrospective observational study used routine bloodstream infection data from the AMR network at Saint Luc Hospital in Kisantu. Blood cultures from suspected bacteremia cases were processed using standard microbiological techniques. Bacterial identification relied on biochemical reactions. Antibiotic susceptibility testing and ESBL-producing NTS detection were performed by disk diffusion following Clinical and Laboratory Standards Institute guidelines. Associations between ESBL production and patient characteristics (age, sex) were assessed using Pearson's Chi-square test, and annual temporal trends in ESBL-producing NTS from 2019 to 2022 were analyzed by logistic regression using 2019 as the reference year.

Results

Of the 19,430 blood cultures, 1681 NTS isolates were identified, and 1568 of these were screened for ESBL. ESBL prevalence was significantly associated with age (p = 0.007), peaking in children under 2 years, but not with sex (p = 0.570). Compared with 2019, the likelihood of isolating ESBL-producing NTS increased markedly through 2022, with adjusted probabilities rising from 58% to 87%, reflecting a strong upward temporal trend. High levels of extensively drug-resistant (94.1%) were observed. No carbapenem resistance was detected.

Conclusions

ESBL-producing NTS bacteremia is rising in Kisantu, DRC, mainly affecting children under 2 years. Rising resistance to key antibiotics limits treatment options and highlights the need for strengthened AMR surveillance, optimized antibiotic use, and vaccination strategies.