Epidemic plasmids in Neisseria gonorrhoeae isolated from high-risk population in Bangladesh

Gonorrhoea still remains as one of the most common venereal diseases, causing a wide range of morbidity among the sexually active people. Characterization of the circulating strains of gonococcus containing epidemic plasmids is important to formulate control strategy. Keeping in mind the above consideration, a total of 495 Neisseria gonorrhoeae isolates with known minimum inhibitory concentration (MIC) values and antimicrobial susceptibility to penicillin and tetracycline were investigated for plasmid content of either PPNG (penicillinase producing N. gonorrhoeae) or TRNG (tetracycline resistant N. gonorrhoeae) or both. Isolates of N. gonorrhoeae showing resistance to penicillin (penicillin MIC ≥ 2 μg/ml, n=255) and high-level tetracycline resistance (tetracycline MIC ≥ 8 μg/ml, n=396) were tested by polymerase chain reaction. The oligonucleotide primers developed to differentiate between three related, epidemic PPNG plasmids (Asia type, Africa type or Toronto/New Zealand type) were used to identify PPNG plasmids and the primers developed to distinguish between American and Dutch variants of Tet-M gene were used to identify TRNG plasmids. A total 169 (34.1%) of the N. gonorrhoeae isolates were found to carry PPNG plasmids and all of them were Africa type showing the amplified products of 3.1 kb. A total 382(77.2%) of the isolates were found positive for TRNG plasmids and almost all were Dutch type (377, 98.7%) with a few American type (5, 1.3%). Although the rate of plasmid infection of either PPNG or TRNG types were very high, because of the presence of only one variant, they are supposed to be endogenously acquired. Therefore, a control strategy, considering the sexual behaviour of the local high risk populations as well as the susceptibility pattern of the circulating N. gonorrhoeae-derived treatment regimen might suffice to control the disease in Bangladesh.