Genetic linkage between serogroup specificity and antibiotic resistance in Neisseria gonorrhoeae

In previous works statistically significant differences were demonstrated in antibiotic susceptibility between gonococcal strains of the recently described W serogroups, W I, W II and W III, respectively. Strains of serogroup W I were almost always sensitive to penicillin and other antibiotics while those of the W II and W III serogroups showed a higher incidence of decreased susceptibility. Transformation experiments were therefore undertaken with an antibiotic sensitive serogroup W I gonococcal strain as recipient and a multi-resistant W II strain as DNA-donor. Transformants, with increased resistance to penicillin and several other antibiotics as compared with the recipient, acquired the same serogroup specificity as the W II donor. With one of these W II transformants as donor and the sensitive W I strain as recipient all transformants acquired the same antibiotic susceptibility pattern as well as the same serogroup as the donor. SDS-PAGE, performed on sarkosyl extracted outer membrane proteins from donor, recipient and some transformants, showed an increase in the molecular weight of the Protein I of the outer membrane of the W II transformants as compared with that of the recipient strain. In rocket-line and crossed-line immunoelectrophoresis the W II transformants could not be distinguished from the W II donor strain. A genetic linkage between antibiotic multi-resistance and serogroup W II specificity was thus shown. This is in agreement with the demonstrated higher incidence of W II strains with increased antibiotic resistance as compared with that of serogroup W I strains.