Molecular characterisation of the first New Delhi metallo-β-lactamase 1-producing Acinetobacter baumannii from Tanzania

Background

We aimed to characterise the genetic determinants and context of two meropenem-resistant clinical isolates of Acinetobacter baumannii isolated from children hospitalised with bloodstream infections in Dar es Salaam, Tanzania.

Methods

Antimicrobial susceptibility was determined by disc diffusion E-test and broth microdilution. Genomes were completed using a hybrid assembly of Illumina and Oxford Nanopore Technologies sequencing reads and characterisation of the genetic context of resistance genes, multi-locus sequence types (ST) and phylogenetic analysis were determined bioinformatically.

Results

Twelve Acinetobacter baumannii were isolated from 2226 blood cultures and two of which were meropenem resistant. The two meropenem resistant isolates, belonging to distinct STs; ST374 and ST239, were found to harbour blaNDM-1, which was chromosomally located in isolate DT0544 and plasmid located in isolate DT01139. The genetic environment of blaNDM- 1 shows the association of insertion sequence ISAba125 with blaNDM-1 in both isolates. Both isolates also harboured genes conferring resistance to other β-lactams, aminoglycosides and cotrimoxazole.

Conclusions

This is the first report of NDM-1 producing isolates of A. baumannii from Tanzania. The genetic context of the blaNDM-1 provides further evidence of the importance of ISAba125 in 44 the spread of blaNDM-1 in A. baumannii. Local surveillance should be strengthened to keep clinicians updated on the incidence of these and other multidrug-resistant and difficult-to- treat bacteria.

Accession numbers: The chromosomal and plasmid sequences of DT0544 and DT01139 were submitted to GenBank with accession numbers PRJNA679703 and PRJNA679704, respectively.