Penicillinase-producing Neisseria gonorrhoeae in Dade County, Florida: phenotypic characterization of isolates from 1983, 1984, and 1986.

Penicillinase-producing strains of Neisseria gonorrhoeae (PPNG) have been endemic in Miami, Florida, since 1981. Strains of PPNG isolated in Miami during 1983 (60 isolates), 1984 (41 isolates), and 1986 (107 isolates) were characterized by plasmid content, auxotype/serovar (A/S) class, and susceptibility to antimicrobial agents. In 1986, 95 isolates (89%) possessed the 3.2-Megadalton (MDa) beta-lactamase plasmid; 36 (34%) of these isolates also possessed the 24.5-MDa conjugative plasmid. These results contrast with those from 1984, when 37 PPNG isolates (90%) possessed the 4.4-MDa plasmid, and most possessed the 24.5-MDa conjugative plasmid. This in turn was a reversal of the pattern seen in 1983, when only 42 (69%) possessed the 3.2-MDa plasmid, and the conjugative plasmid was rare. In 1983 and 1986, isolates possessing the 4.4-MDa plasmid were more resistant to penicillin than were isolates containing the 3.2-MDa plasmid. All isolates were susceptible to spectinomycin and ceftriaxone. In early 1986, two A/S classes accounted for 66% of all isolates. Pro/IA-1,2 and Pro/IB-2 accounted for 31 (29%) and 40 (37%), respectively, and were isolated during every week in early 1986. In contrast, isolates belonging to 14 and six A/S classes possessing the 3.2- and 4.4-MDa beta-lactamase plasmid, respectively, were isolated sporadically. The composition of the PPNG strain population in Miami is dynamic, a factor that may have important implications for the use of traditional disease intervention strategies.