Multiple ST clonal complexes, with a predominance of ST131, of Escherichia coli harbouring blaCTX-M-15 in a tertiary hospital in Tanzania

The molecular epidemiology of 32 non-duplicate, CTX-M-15 extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli strains, isolated from clinical samples, was investigated. Multilocus sequence typing revealed multiple sequence type clonal complexes: ST131 (12), ST405 (4), ST638 (3), ST38 (2), ST827 (2), ST224 (1), ST648 (1), ST46 (1) and two new sequence type clonal complexes (1845 and 1848) in 22 pulsed field gel electrophoresis clusters. The blaCTX-M-15 gene was located on conjugative IncF plasmids. This is the first report of the worldwide emerging clonal complex ST131 linked to blaCTX-M-15 in Tanzania and demonstrates the need for constant surveillance in developing countries to prevent the spread of these multiresistant isolates.