Cases of a strain of gonorrhoea impervious to an antibiotic have almost tripled in six months, the latest report from the National Alert System for Critical Antimicrobial Resistance (CARAlert) reveals.

The result was a “warning shot across the bow” for doctors and public health officials fighting antibiotic resistance, CARAlert’s senior medical adviser said.

A total of 742 reports of critically resistant bacteria were collected by the early-warning system from 65 laboratories nationwide between April and September last year, a 75 per cent rise on the 423 cases reported in the same period during 2016.

A spike in the number of reports of Neisseria gonorrhoeae, a bacterial strain responsible for gonorrhoea that is resistant to the antibiotic azithromycin, accounted for most of the overall increase.