First Report of IMI-2-Producing Enterobacter bugandensis and CTX-M-55-Producing Escherichia coli isolated from Healthy Volunteers in Tunisia

Abstract

The aim of this study was to characterize the prevalence of fecal carriage of extended-spectrum beta-lactamases and carbapenemase-producing Gram-negative bacteria among healthy humans in Tunisia. Fifty-one rectal swabs of healthy volunteers were plated on MacConkey agar plates supplemented with cefotaxime or imipenem. The occurrences of resistance genes, integrons, and phylogroup typing were investigated using PCR and sequencing. The genetic relatedness of isolates was determined by pulsed-field-gel-electrophoresis (PFGE) and multilocus-sequence-typing (MLST). Whole-genome-sequencing (WGS) was performed for the carbapenem-resistant isolate. Sixteen ESBL-producing Escherichia coli isolates and one carbapenem-resistant Enterobacter bugandensis were detected out of the fifty-one fecal samples. The ESBL-producing E. coli strains contained genes encoding CTX-M-15 (n = 9), CTX-M-1 (n = 3), CTX-M-27 (n = 3), and CTX-M-55 (n = 1). Three CTX-M-1-producers were of lineages ST131, ST7366, and ST1158; two CTX-M-15-producers belonged to lineage ST925 and ST5100; one CTX-M-27-producer belonged to ST2887, and one CTX-M-15-producer belonged to ST744. Six isolates contained class 1 integrons with the following four gene cassette arrangements: dfrA5 (two isolates), dfrA12-orf-aadA2 (two isolates), dfrA17-aadA5 (one isolate), and aadA1 (one isolate). E. bugandensis belonged to ST1095, produced IMI-2 carbapenemase, and contained qnrE1 and fosA genes. A genome-sequence analysis of the E. bugandensis strain revealed new mutations in the blaACT and qnr genes. Our results reveal an alarming rate of ESBL-E. coli in healthy humans in Tunisia and the first description of IMI-2 in E. bugandensis.

The Importance of Carbapenemase-Producing Enterobacterales in African Countries: Evolution and Current Burden

“…Another 2022 study, in which 227 hospitalized children were screened for MDR Enterobacteriaceae rectal colonization, reported only 1 patient (0.44%) with CPE carriage (a strain of bla OXA-48 Klebsiella oxytoca) [152]. In 2023, the first report of IMI-2-producing Enterobacter bugandensis isolated from the stool of a healthy volunteer in Tunisia was published [153]. Overall, although significant rates of CPE were observed generally, CPE carriage seems to be under 1% in Tunisia.…”

Antimicrobial resistance and biotechnological potential of plastic‐associated bacteria isolated from an urban estuary

“…One strain of Enterobacter bugandensis harboured the mcr‐3 gene along with bla KPC (Table S4). Enterobacter species are considered highly pathogenic, with an opportunistic tendency in healthcare environments and as potential carriers of ARGs (Ben Sallem et al, 2023; Doijad et al, 2016; Pati et al, 2018). However, the description of the simultaneous carriage of mcr‐3 and bla KPC , two genes encoding resistance to last‐resort antibiotics, is scarce and raises attention to the dissemination of pathogenic and antimicrobial‐resistant bacteria in plastic samples found in a recreational environment.…”