Carbapenem-resistant bacteria spread from Benin hospitals into household contacts

Carbapenem-resistant bacteria colonized a growing share of hospitalized patients and their caregivers in Benin during a new study, and the burden continued to rise after patients returned home. Researchers report that among people enrolled at a hospital, the prevalence of carbapenem-resistant bacterial colonization increased from 7.3 percent (16 of 220; 95 percent CI 4.5–11.5) at admission to 22.7 percent (10 of 44; 95 percent CI 12.8–37.0) by day 8 of hospitalization. Among patients or caregivers who were still positive at discharge, prevalence at home rose from 8.0 percent (7 of 87; 95 percent CI 4.0–15.7) on the day of discharge to 57.1 percent (8 of 14; 95 percent CI 32.6–78.6) by day 14 of follow-up.

The study, published in Antimicrobial Resistance & Infection Control, set out to assess whether carbapenem-resistant organisms move from hospitals to households through patients and their caregivers. Carbapenems are described in the paper as last-resort antibiotics in the healthcare system today, and patients can acquire and become colonized by carbapenemase-producing Gram-negative bacteria during hospitalization, which may then be transmitted to household contacts after discharge.

In total, 248 participants were included across five hospitals: 81 index patients, 81 caregivers, 58 healthcare workers, and 28 household members. Rectal swab samples were collected from participants from admission to discharge and during follow-up at home. Samples were plated on mSuperCARBA™, and the obtained isolates were tested for carbapenem resistance.

Overall, 141 carbapenem-resistant isolates were recovered from rectal swab samples collected in hospital and household settings. The isolates were predominantly E. coli (40.4 percent), Klebsiella pneumoniae (19.1 percent), and Acinetobacter baumannii (10.6 percent). A subset of 41 carbapenem-resistant isolates was selected and subjected to whole genome sequencing with hybrid assembly analysis to determine genetic relatedness and resistance determinants across the sampling networks.

Sequencing of long and short reads identified the carbapenem resistance genes blaNDM-5 and blaNDM-1 as the main determinants, found in E. coli ST410 and K. pneumoniae ST147, respectively. Several strains, including K. pneumoniae ST147 and E. coli ST410, showed genetic relatedness and potential transmission within households and between healthcare and home settings, according to the authors.

The genomic analysis also pointed to plasmids as a vehicle for resistance spread. IncFII and IncFI conjugative plasmids carried most of the carbapenemase genes, in addition to a multitude of other antimicrobial resistance genes, in healthcare and community settings. The authors describe this as another layer of resistance spread via horizontal gene transfer, meaning resistance genes can move between bacteria rather than only being passed down through bacterial lineages.

The authors state that the study reveals, for the first time in Benin, the role of patients and their caregivers in facilitating the spread of antimicrobial resistance between hospitals and the community. The finding places caregivers, who were sampled alongside patients throughout admission and follow-up, at the center of a transmission network that links hospital wards to homes.

The study’s design has limits worth noting. Colonization was measured through rectal swabs and culture on a selective medium, so the findings concern carriage of resistant organisms rather than diagnosed infections. The day-8 and day-14 prevalence figures rest on small denominators, 44 and 14 people respectively, which is reflected in the wide confidence intervals, and the 41 sequenced isolates were a subset of the 141 recovered. The authors describe genetic relatedness and potential transmission, a characterization that stops short of confirming the direction of every transmission event.

Even so, the work documents a measurable increase in colonization from admission through hospitalization and into the home follow-up period, and it identifies the resistance genes, bacterial lineages, and conjugative plasmids circulating across both settings in Benin. The article was published on 24 September 2026 as an open-access research paper, and the version shared at publication is subject to further edits before the final Version of Record replaces it.

Subject of Research: Transmission of carbapenemase-producing Gram-negative bacteria between hospitals and households in Benin

Article Title: Transmission dynamics of carbapenemase-producing Gram-negative bacteria and mobile genetic elements between hospital and household settings in Benin

Article References: Sintondji, K., Dougnon, V., Lègba, B., Hougbénou, B.-G., Fabiyi, K., Koudokpon, H., Dalsgaard, A., & Hounmanou, Y. M. G. (2026). Transmission dynamics of carbapenemase-producing Gram-negative bacteria and mobile genetic elements between hospital and household settings in Benin. Antimicrobial Resistance & Infection Control. https://doi.org/10.1186/s13756-026-01814-8

Image Credits: AI Generated

DOI: 10.1186/s13756-026-01814-8

Keywords: carbapenem resistance, antimicrobial resistance, Gram-negative bacteria, Benin, whole genome sequencing, blaNDM-5, blaNDM-1, household transmission, hospital infection control, E. coli, Klebsiella pneumoniae, plasmids