Mobile antimicrobial resistance in Neisseria gonorrhoeae 

Neisseria gonorrhoeae (the gonococcus) is the causative agent of the sexually-transmitted infection gonorrhoea, and has developed resistance to all classes of antimicrobials. In gonococci, plasmids can mediate high-level antimicrobial resistance (AMR) to tetracyclines and ß-lactams. Plasmids can spread through bacterial populations by transformation and conjugation, resulting in the rapid dissemination of traits. Characterisation of plasmids, including understanding their distribution in bacterial populations, is therefore key to understanding bacterial evolution, and in particular the spread of AMR. N. gonorrhoeae can harbour three plasmids, conjugative (pConj), ß-lactamase (pbla) and cryptic (pCryp). Using genomic and phylogenetic analyses, we show that plasmids are widespread in a large collection of gonococcal isolates from 56 countries. We found that variants of pConj (which can mediate tetracycline resistance) and pbla expressing TEM-135 ß-lactamase are associated with distinct gonococcal lineages. Furthermore, AMR plasmids are significantly more prevalent in gonococci from less wealthy countries. Over 94% of gonococci possess the cryptic plasmid (pCryp), and its absence can be correlated with the presence of a novel chromosomal Type IV secretion system. Our results reveal the extent of plasmid-mediated AMR in the gonococcus, particularly in less wealthy countries, where diagnostic and therapeutic options can be limited, and highlight the risk of their global spread.