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Epidemiologic Notes and Reports Outbreak of a Distinct Strain of Penicillinase-Producing Neisseria gonorrhoeae -- King County, Washington

In 1986, penicillinase-producing Neisseria gonorrhoeae (PPNG) infections accounted for approximately 2% of gonorrhea reported in the United States, a 90% increase over the 1985 percentage (1). The majority of PPNG cases were reported in Florida, New York, and California. Except for a brief outbreak in 1980 (2), King County (Seattle), Washington, had reported sporadically occurring cases of PPNG until the incidence began to increase in the second half of 1986.

The incidence of PPNG increased substantially in King County in 1987. Eighty-four (5%) of the 1,784 cases of gonorrhea reported in King County from January 1 through June 30, 1987, were PPNG, whereas 30 (0.8%) of the 3,990 gonorrhea cases reported in 1986 were PPNG. The PPNG cases reported during the first half of 1987 included two cases of disseminated gonococcal infection (DGI) and one case of adult gonococcal ophthalmia. Eight (5%) of 164 reported cases of gonococcal pelvic inflammatory disease were PPNG. Thirty-one (37%) of the PPNG infections occurred in women; 52 (62%), in heterosexual men; and one, in a bisexual man. The increase appears to be limited to King County since immediately adjacent counties reported only 13 PPNG cases during the same time period. The evidence in this outbreak does not indicate that PPNG was imported from other areas of the United States or from other countries.

Seventy-five (89%) of the PPNG isolates found during the first half of 1987 belong to a single auxotype/serovar (A/S) class of N. gonorrhoeae (Figure 1). The epidemic strain is a proline-requiring auxotype, Protein IA-4 serovar. The proportion of PPNG cases caused by other A/S classes remained stable in the community. All PPNG isolates of the epidemic strain have had characteristic antimicrobial susceptibilities, with minimum inhibitory concentration ranges: penicillin G greater than 8 ug/mL, tetracycline 0.125-0.5 ug/mL, spectinomycin 16 ug/mL, cefoxitin 0.5-1.0 ug/mL, and ceftriaxone 0.001-0.004 ug/mL.

To control this outbreak, the Seattle-King County Department of Public Health has intensified its case finding, interviewing, and partner-tracing efforts and has advised all clinical facilities to increase their screening efforts. The health department, in cooperation with the King County Medical Society and local media, has advised all health providers to use only ceftriaxone or spectinomycin as initial therapy for all persons suspected or proven to have gonorrhea (3). In accordance with CDC treatment guidelines (3,4), a 7-day course of tetracycline or doxycycline for possible coexistent chlamydial infection continues to be recommended for all patients with gonorrhea. Providers have also been advised to confirm all suspected cases by culture to allow screening for beta-lactamase production and to immediately report all confirmed PPNG infections by telephone to the health department. Reported by: RJ Rice, MD, HH Handsfield, MD, R Tulloch, Seattle-King County Dept of Public Health and University of Washington, Seattle; L Klopfenstein, M Donnelly, JM Kobayashi, MD, State Epidemiologist, Washington Dept of Social and Health Svcs. Sexually Transmitted Diseases Laboratory Program, Center for Infectious Diseases; Div of Sexually Transmitted Diseases, Center for Prevention Svcs, CDC.

Editorial Note

Editorial Note: PPNG outbreaks caused by organisms belonging to a single A/S class are uncommon. Recent reported outbreaks from Denver (5), Miami (6), and Amsterdam (7) have all implicated multiple strains in endemic transmission. It is unclear whether multiple-strain outbreaks arise because of importation of different PPNG strains into a community or through the conjugal transfer of plasmids that code for beta-lactamase from native PPNG strains to non-PPNG gonococci.*

Single-strain PPNG epidemics in the United States were suspected in 1980 (2) in Seattle and in Shreveport, Louisiana. At that time, complete A/S classification was not possible. In single-strain epidemics, eradication of PPNG from a community may be feasible. In the United States (2) and in Sweden (8), eradication efforts have been more successful in areas where single-strain PPNG has been suspected. A/S classification may be useful as an adjunct to the management guidelines for the control of antibiotic-resistant strains of N. gonorrhoeae recently published by CDC (3).


  1. Centers for Disease Control. Penicillinase-producing Neisseria gonorrhoeae--United States, 1986. MMWR 1987;36:107-8.

  2. Handsfield HH, Sandstrom EG, Knapp JS, et al. Epidemiology of penicillinase-producing Neisseria gonorrhoeae infections: analysis by auxotyping and serogrouping. N Engl J Med 1982;306:950-4.

  3. Centers for Disease Control. Antibiotic-resistant strains of Neisseria gonorrhoeae: policy guidelines for detection, management, and control. MMWR 1987;36(suppl 5S).

  4. Centers for Disease Control. 1985 STD treatment guidelines. MMWR 1985;34(suppl 4S).

  5. Centers for Disease Control. Multiple strain outbreak of penicillinase-producing Neisseria gonorrhoeae--Denver, Colorado, 1986. MMWR 1987;36:534-6,542-3.

  6. Zenilman JM, Knapp JS, Whittington WL, et al. Characterization of penicillinase-producing Neisseria gonorrhoeae (PPNG) strains from Miami, Florida (Abstract). In: Hartman PA, ed. Abstracts of the American Society for Microbiology. Washington, DC: American Society for Microbiology, 1987:369.

  7. Ansink-Schipper MC, Bygdeman SM, van Klingeren B, Sandstrom EG. Serovars, auxotypes, and plasmid contents of PPNG strains from outbreak in Amsterdam. Genitourin Med 1987;63:157-9.

  8. Ramstedt KM, Hallhagen GJ, Bygdeman SM, et al. Serologic classification and contact-tracing in the control of microepidemics of beta-lactamase-producing Neisseria gonorrhoeae. Sex Transm Dis 1985;12:209-14. *Scientists hypothesize that conjugal transfer of beta-lactamase plasmids may occur when an infection consists of PPNG and non-PPNG strains (a mixed infection).

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