First detection of an OXA-48-producing Enterobacter cloacae isolate from currency coins in Algeria

Objectives: The aim of this study was to screen for the presence of β-lactamase-producing Gram-negative bacteria (GNB) from Algerian currency collected from food vendors in Batna city, Algeria.

Methods: During two periods (May 2018 and March-April 2019), a total of 408 coins and currency notes of different denominations of Algerian Dinar were randomly recovered from several food vendors. Samples were subjected to selective isolation of extended-spectrum cephalosporin- and carbapenem-resistant GNB. Bacterial species identification was performed using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Antibiotic susceptibility testing was performed by the disk diffusion method. Carbapenemase and extended-spectrum β-lactamase (ESBL) genes were searched for by real-time PCR, standard PCR and sequencing. The clonal relationship of carbapenemase-producing isolates was investigated by multilocus sequence typing (MLST). The transferability of the detected carbapenemase-encoding gene was verified by conjugation experiments.

Results: Twelve cefotaxime- and/or carbapenem-resistant strains were isolated in this study and were identified as Enterobacter cloacae, Raoultella ornithinolytica, Citrobacter freundii, Escherichia coli, Pseudomonas aeruginosa, Pseudomonas libanensis and Pseudomonas stutzeri. The bla_OXA-48 gene was detected in only one E. cloacae strain belonging to sequence type 108 (ST108), whilst the two R. ornithinolytica isolates harboured bla_CTX-M-27 and one E. coli strain carried bla_CTX-M-14. The detected bla_OXA-48 gene was transferable by conjugation.

Conclusions: We report for the first time the detection of an OXA-48-producing E. cloacae isolate from money. This calls for consciousness development on the potential risks associated with poor handling of currency.