There are two main types of antibiotic resistance in N. gonorrhoeae: chromosomal resistance involves penicillins and a wide range of other therapeutic agents such as tetracyclines, spectinomycin, erythromycin, quinolones, thiamphenicol, and cephalosporins; plasmid-mediated resistance affects penicillins and tetracyclines. Chromosomally resistant N. gonorrhoeae, penicillinase-producing gonococci, and plasmid-mediated, tetracycline- resistant strains are all increasing and have had a major impact on the efficacy of traditional regimens for treating gonorrhoea.
Chromosomal resistance in N. gonorrhoeae has been observed since the introduction of sulphonamides in the 1930s. Its significance today is that chromosomal resistant strains are often resistant to a number of antimicrobial agents that have been used to treat gonorrhoea. There is also cross-resistance between penicillin and the second- and third-generation cephalosporins. Although not yet of any clinical relevance in relation to the use of ceftriaxone, this trend is disturbing. The high level spectinomycin resistance reported sporadically in gonococci is also chromosomally mediated.
The effectiveness and usefulness of current surveillance of gonococcal resistance are limited, and a simple instrument for assessing and monitoring gonococcal antimicrobial resistance needs to be developed. Lack of standardization of sensitivity testing methodology continues to be a problem. Standard methods should be used and should include a set of reference strains. Disc-diffusion sensitivity testing remains poorly standardized, one problem being the limited availability of antibiotic discs of the correct content.