Epidemiology of penicillinase-producing Neisseria gonorrhoeae infections: analysis by auxotyping and serogrouping.

Auxotyping and serogrouping by coagglutination were used to characterize penicillinase-producing Neisseria gonorrhoeae and penicillinase-negative isolates from the state of Washington, Shreveport (Louisiana), and the Far East. Fifty-four of 75 penicillinase-producing isolates (72 per cent) from Washington required proline for growth and were serogroup W-l (Pro-1), the predominant type of penicillinase-producing strains in the Philippines; none of 86 penicillinase-negative isolates from Washington was Pro-1 (P less than 0.0001). All 38 penicillinase-producing isolates from Shreveport required proline and were serogroup W-11 (Pro-11); five of 26 penicillinase-negative isolates (19 per cent) from Shreveport were also Pro-11 (P less than 0.0001) but had antigenic specificities within serogroup W-ll that distinguished them from the penicillinase-producing isolates. We conclude that the Washington and Shreveport outbreaks resulted from the spread of imported strains rather than transmission of penicillinase-encoding plasmids to indigenous gonococci. The Shreveport outbreak involved a single strain of penicillinase-producing N, gonorrhoeae and probably originated from a common source, whereas several types were involved in the multiple-source Washington outbreak, indicating repeated introduction of new strains.