High levels of ceftriaxone resistance in Vietnam, 2023

We describe the highest ceftriaxone-resistance levels reported in any country (26·9%), mainly caused by widespread dissemination of penA-237.001-containing (especially in Hanoi) and penA-60.001-containing ceftriaxone-resistant strains (particularly in HCMC). Of the ceftriaxone resistance, 88·1% was caused by other penA alleles than penA-60.001, which several currently-used PCRs predicting ceftriaxone resistance are targeting. Consequently, these assays will miss most ceftriaxone resistance in Vietnam. Accordingly, we have developed a PCR detecting both penA-60.001 and penA-237.001 for use in Vietnam. In the Vietnamese gonorrhoea guidelines, first-line treatment is ceftriaxone 250mg plus azithromycin 1g and second-line is cefixime 400mg plus azithromycin 1g. Based on our present results, ceftriaxone 1g with mandatory test-of-cure should be recommended, ideally combined with azithromycin 2g (at least for treatment failures and pharyngeal infections), for all gonorrhoea cases, which would be in accordance with the soon published global WHO treatment guideline. Importantly, based on case reports2 and pharmacodynamic studies,5 ceftriaxone 1g can cure most cases caused by ceftriaxone-resistant strains with MICs of 0·25-0·5 mg/L (94·0% (63/67) in Vietnam in 2023). Furthermore, cefixime should not be used if ceftriaxone is available.