Molecular epidemiology of Neisseria gonorrhoeae exhibiting decreased susceptibility and resistance to ciprofloxacin in Hawaii, 1991-1999.

BACKGROUND: Clinically significant resistance to Centers for Disease Control and Prevention (CDC)-recommended doses of fluoroquinolones (ciprofloxacin and ofloxacin) has been reported for Neisseria gonorrhoeae. In Hawaii, fluoroquinolone-resistant gonococcal isolates were first identified in 1991. GOAL: To assess the diversity, based on phenotypic and genotypic characterization, of gonococcal isolates exhibiting decreased susceptibility (CipI; MICs = 0.125-0.5 microg/ml) or clinically significant resistance (CipR; MICs > or = 1 microg/ml) to ciprofloxacin in Hawaii from 1991 through 1999. STUDY DESIGN: Antimicrobial susceptibilities, auxotype/serovar (A/S) class, GyrA/ParC alteration patterns, and plasmid profiles were determined for gonococci isolated in Honolulu from 1991 through 1999 that exhibited intermediate or clinically significant resistance to ciprofloxacin. Strain phenotypes were defined by A/S class, GyrA/ParC alteration pattern, and penicillin-tetracycline resistance phenotype supplemented with plasmid profiles for beta-lactamase-producing isolates. RESULTS: Altogether, 68 isolates exhibiting intermediate or clinically significant resistance to ciprofloxacin belonged to 23 and 19 strain phenotypes, respectively. Among the CipI and CipR isolates, 4 and 13 GyrA/ParC alterations patterns were identified, respectively. The 91,95/Asp-86 alteration pattern occurred most frequently among CipR isolates. Forty-four strain phenotypes were represented by only one isolate. In addition, seven pairs and two clusters of isolates were identified. CONCLUSIONS: From 1991 through 1997, few gonococcal strains exhibiting intermediate or clinically significant resistance to CDC-recommended doses of fluoroquinolones were identified from Hawaii. Isolates belonged to a large number of phenotypic and genotypic types, suggesting that most cases were imported, with only a few instances in which isolate pairs indicated that secondary transmission of infections had occurred in Hawaii. Beginning in 1998, the number of CipR isolates increased markedly, and more isolates belonged to fewer phenotypic and genotypic types, suggesting either more frequent importation of fewer strain types or the possibility that the endemic spread of a few strains is beginning to occur.

Intercity spread of gonococci with decreased susceptibility to fluoroquinolones: a unique focus in the United States.

Patients and gonococcal isolates (n = 783) from five sexually transmitted disease clinics in Ohio and western Pennsylvania were studied to investigate the spread of gonococci with decreased fluoroquinolone susceptibility. Among patients with gonorrhea, rates of infection with strains with decreased fluoroquinolone susceptibility (MIC of 0.125-0.25 microg ciprofloxacin/mL) were 20% for Cleveland, 9% for Akron, 7% for Columbus, 1% for Toledo, and 0.5% for Pittsburgh. Persons infected with strains with decreased susceptibility were more likely than those with susceptible strains to be male and older; no significant differences in sex behaviors, residence of sex partners, or recent antibiotic use were detected. Prevalence of decreased susceptibility was not correlated with reported levels of community fluoroquinolone use. The Pro/IB-3 auxotype/serovar class accounted for 80% (44/55) of isolates with decreased susceptibility. Pro/IB-3 isolates from three cities had indistinguishable pulsed-field gel electrophoresis patterns, suggesting intercity spread of a clone.

Antimicrobial susceptibilities of strains of Neisseria gonorrhoeae in Bangkok, Thailand: 1994-1995.

BACKGROUND AND OBJECTIVES: Failure of uncomplicated gonococcal infections acquired in the Far East to respond to doses of ciprofloxacin and ofloxacin recommended by the Centers for Disease Control and Prevention have been identified in Australia, the United Kingdom, and the United States. In the Republic of the Philippines, 54.3% of strains exhibited decreased susceptibility to fluoroquinolones; 12% of strains were resistant to ciprofloxacin. This study was undertaken to compare the antimicrobial susceptibilities of gonococcal isolates in Bangkok, Thailand, with those in the Republic of the Philippines. GOAL: To determine the frequency and diversity of antimicrobial resistance, particularly to fluoroquinolones, in gonococcal strains in Bangkok, Thailand. STUDY DESIGN: Strains of Neisseria gonorrhoeae isolated from 101 patients with uncomplicated gonorrhea in Bangkok, Thailand, in July, 1994 (46 strains) and November, 1994 to July, 1995 (55 strains), were characterized by auxotype/serovar class, antimicrobial susceptibilities, and plasmid profile. Susceptibilities were determined to penicillin G, tetracycline, ceftriaxone, cefixime, cefoxitin, ciprofloxacin, ofloxacin, norfloxacin, erythromycin, kanamycin, and thiamphenicol. RESULTS: Of 101 strains, 89.1% (90/101) were resistant to penicillin or tetracycline. Plasmid-mediated resistance to penicillin or tetracycline was identified in 33.7% (34/101) of the isolates: penicillinase-producing Neisseria gonorrhoeae (17.8%; 18/101), tetracycline-resistant Neisseria gonorrhoeae (7.9%; 8/101), and penicillinase-producing/tetracycline-resistant Neisseria gonorrhoeae (7.9%; 8/101). Most penicillinase-producing strains (96.2%; 25/26) possessed the 4.4-megadalton (Md) beta-lactamase plasmid; one strain possessed the 3.2-Md beta-lactamase plasmid. Chromosomally mediated resistance to penicillin and tetracycline was exhibited by 51.5% (52/101) of strains, and 4.0% (4/101) were tetracycline resistant. All strains were susceptible to spectinomycin. Of 21.8% (22/101) strains exhibiting decreased susceptibility to ciprofloxacin (minimal inhibitory concentration [MIC] > or = 0.125 microgram/ml), one strain (ciprofloxacin MIC, 0.5 microgram/ml; ciprofloxacin inhibition zone diameter of 23 mm) had MICs of 2.0 and 8.0 micrograms/ml for ofloxacin and norfloxacin, respectively, indicating resistance to these agents. Decreased susceptibility to ciprofloxacin was identified in strains with chromosomally mediated resistance to penicillin or tetracycline and in penicillinase-producing strains. CONCLUSIONS: In Bangkok, Thailand, gonococcal isolates exhibit resistance to penicillin, tetracycline, kanamycin, and thiamphenicol. Decreased susceptibility to fluoroquinolones is emerging in a variety of strains of N. gonorrhoeae. Thus, all gonococcal infections should be treated with antimicrobial therapies known to be active against all gonococcal strains to reduce the spread of strains exhibiting decreased susceptibilities to fluoroquinolones.

PIP: To assess the frequency and diversity of antimicrobial resistant strains of Neisseria gonorrhoeae in Thailand, endocervical or urethral strains were isolated from 101 patients at a Bangkok sexually transmitted disease clinic. Of the 101 strains, 90 (89.1%) were resistant to penicillin or tetracycline. Plasmid-mediated resistance to penicillin or tetracycline was found in 33.7% of isolates; this included penicillinase-producing N gonorrhoeae (17.8%), tetracycline-resistant N gonorrhoeae (7.9%), and penicillinase-producing/tetracycline-resistant N gonorrhoeae (7.9%). Moreover, 51.5% of all strains exhibited chromosomally mediated resistance to penicillin and tetracycline. All strains were susceptible to spectinomycin. 22 strains (21.8%) showed decreased susceptibility to ciprofloxacin, while another fifth demonstrated resistance to both fluoroquinolones and norfloxacin. Finally, more than 75% of strains exhibited decreased susceptibility to kanamycin and thiamphenicol. The penicillin/tetracycline resistance phenotypes identified in Bangkok were more similar to those of isolates in the US than in the Philippines, where decreased susceptibility to fluoroquinolones predominates. Given evidence of antimicrobial resistance to penicillin, tetracycline, kanamycin, thiamphenicol, and fluoroquinolones in Thailand, the choice of agents for the treatment of uncomplicated gonococcal infection should be considered carefully and periodic surveillance of antimicrobial resistance is recommended to permit timely revision of treatment protocols.

Molecular epidemiology, in 1994, of Neisseria gonorrhoeae in Manila and Cebu City, Republic of the Philippines.

BACKGROUND AND OBJECTIVES: Failure of gonococcal infections to respond to 500 mg of ciprofloxacin or 400 mg of ofloxacin has been reported from Australia, the United Kingdom, and the United States. Recently, high rates of decreased susceptibility to the fluoroquinolones have been detected in penicillinase-producing Neisseria gonorrhoeae in the Republic of the Philippines. GOALS: To assess the diversity of antimicrobial-resistant gonococcal strains isolated from female sex workers in Manila and Cebu City in the Republic of the Philippines in 1994. STUDY DESIGN: Isolates of N. gonorrhoeae isolated from 92 female sex workers in Manila (n = 28) and Cebu City (n = 64), respectively, were characterized by plasmid profile, auxotype/serovar class, and antimicrobial susceptibility profile. RESULTS: Plasmid-mediated resistance to penicillin or tetracycline was identified in 79.3% (73/92) of the isolates: penicillinase-producing N. gonorrhoeae (65/92; 70.7%), tetracycline-resistant N. gonorrhoeae (6/92; 6.5%), and penicillinase-producing/tetracycline-resistant N. gonorrhoeae (1/92; 1.1%). A beta-lactamase plasmid of 3.9 megadaltons was discovered. Of 54.3% (50/92) of strains resistant to nalidixic acid, 84% (42/50) of strains had minimum inhibitory concentrations of > or = 0.125 microgram/ml ciprofloxacin; penicillinase-producing N. gonorrhoeae (possessing the 3.05-, 3.2-, 3.9-, and 4.4-megadalton beta-lactamase plasmids, respectively) accounted for 68% (34/50) of these strains. CONCLUSIONS: In the Republic of the Philippines, gonococcal isolates resistant to penicillin or tetracycline accounted for 85.9% (79/92) of the isolates examined and included strains exhibiting resistance to fluoroquinolones. All gonococcal infections should be treated with antimicrobial therapies known to be active against all gonococcal strains to reduce the spread of strains exhibiting decreased susceptibilities to fluoroquinolones.

PIP: During July-October 1994 in the Philippines, Neisseria gonorrhoeae were isolated from 92 female sex workers in Manila and Cebu City. The purpose was to characterize the gonococcal strains by plasmid content, auxotype, serovar, and antimicrobial susceptibilities in order to examine the diversity of antimicrobial-resistant N gonorrhoeae strains in these sex workers. Penicillinase-producing N gonorrhoeae (PPNG) comprised 70.7% of the isolates. Strains with the 3.2-megadalton (Mda) beta-lactamase plasmid were more common in Cebu City than in Manila (57.8% vs. 28.6%; p = 0.02). They had significantly lower minimum inhibitory concentrations (MICs) to penicillin, tetracycline, ceftriaxone, ciprofloxacin, and erythromycin than did strains with 3.05-, 3.9-, or 4.4-Mda plasmid (p 0.01). One PPNG strain had a previously undescribed 3.9-Mda beta-lactamase plasmid. It also had a 24.5-Mda conjugative plasmid. Only 15.2% of all 92 isolates were susceptible to both penicillin and tetracycline. Tetracycline-resistant N gonorrhoeae (TRNG) comprised 6.5% of the isolates. 1.1% of isolates were resistant to both penicillin and tetracycline. 54.3% of all strains were resistant to nalidixic acid (fluoroquinolone), 84% of which had MICs of at least 0.125 mcg/ml ciprofloxacin. 68% of the nalidixic acid-resistant strains had 4.4 Mda beta-lactamase plasmids. 85.9% of all gonococcal isolates exhibited resistance to penicillin or tetracycline. They also included strains exhibiting resistance to fluoroquninolones. These findings reveal the need for periodic surveillance for resistance in N gonorrhoeae to the antimicrobial agents used for primary gonorrhea therapy in order to improve the treatments of choice.

Proposed criteria for interpretation of susceptibilities of strains of Neisseria gonorrhoeae to ciprofloxacin, ofloxacin, enoxacin, lomefloxacin, and norfloxacin.

The susceptibilities of 45 strains of Neisseria gonorrhoeae, including 25 strains susceptible to ciprofloxacin (MICs, < or = 0.06 microgram/ml) and 20 strains exhibiting decreased susceptibilities to ciprofloxacin (MICs, > or = 0.125 microgram/ml), to ciprofloxacin, ofloxacin, enoxacin, lomefloxacin, norfloxacin, and nalidixic acid were determined by agar dilution and disk diffusion. On the basis of theoretical calculations of predicted susceptibilities at which infections may fail therapy (supported by observed failures of infections to respond to the therapeutic doses of enoxacin and ciprofloxacin), the Centers for Disease Control and Prevention has adopted the following agar dilution breakpoints for interpretation of resistance to these agents: MICs of > or = 1.0 microgram of ciprofloxacin, enoxacin, and norfloxacin per ml and MICs of > or = 2.0 micrograms of ofloxacin and lomefloxacin per ml. The corresponding disk diffusion breakpoints for these agents were as follows: ciprofloxacin, < or = 29 mm; ofloxacin, < or = 24 mm; enoxacin, < or = 31 mm; lomefloxacin, < or = 26 mm; and norfloxacin, < or = 32 mm. The Centers for Disease Control and Prevention recommends two strains as interim quality control strains for susceptibility testing of ciprofloxacin and ofloxacin. These are N. gonorrhoeae CDC-10,328 (MIC of ciprofloxacin, 0.125 to 0.25 microgram/ml [inhibition zone diameter range, 30 to 34 mm]; MIC of ofloxacin, 0.5 microgram/ml [inhibition zone diameter range, 27 to 32 mm]) and N. gonorrhoeae CDC-10,329 (MIC of ciprofloxacin, 1.0 to 2.0 micrograms/ml [zone inhibition diameter range, 21 to 26 mm]; MIC of ofloxacin 2.0 micrograms/ml [inhibition zone diameter range, 18 to 21 mm]).

In vitro activity of a new fluoroquinolone, CP-99,219, against strains of Neisseria gonorrhoeae.

The susceptibilities of 216 strains of Neisseria gonorrhoeae to a new fluoroquinolone, CP-99,219 were determined. For strains for which the MICs of ciprofloxacin were < or = 0.06 microgram/ml, the MICs at which 90% of the isolates are inhibited (MIC90s) of CP-99,219, ciprofloxacin, and ofloxacin were 0.008, 0.015, and 0.03 microgram/ml, respectively. For strains for which the MICs of ciprofloxacin were 0.125 to 0.5 microgram/ml, the MIC90s of CP-99,219, ciprofloxacin, and ofloxacin were 0.06, 0.25, and 0.5 microgram/ml, respectively. For strains for which the MICs of ciprofloxacin and ofloxacin were 2.0 micrograms/ml, the MIC of CP-99,219 was 0.25 microgram/ml.

Persistence of Neisseria gonorrhoeae strains with decreased susceptibilities to ciprofloxacin and ofloxacin in Cleveland, Ohio, from 1992 through 1993.

Twenty-five isolates of beta-lactamase-negative strains of Neisseria gonorrhoeae exhibiting decreased susceptibilities to ciprofloxacin (MIC, > or = 0.125 microgram/ml) were isolated from men with uncomplicated gonococcal urethritis in Cleveland, Ohio, from January 1992 through June 1993. The strains belonged to three auxotype-serovar classes: Pro-IB-1 (2 isolates), Pro-IB-2 (21 isolates), and Pro-IB-3 (2 isolates). MICs for strains were in the intermediate or resistant categories for penicillin, the intermediate or susceptible categories for tetracycline (with the exception of one strain that had acquired the 25.2-MDa TetM-containing plasmid) and cefoxitin, and the susceptible categories for ceftriaxone and cefixime (MICs, < or = 0.25 microgram/ml) and spectinomycin (MIC, < or = 256 micrograms/ml). MICs for strains were also in the susceptible category for ofloxacin (MIC, 0.25 microgram/ml) and in categories higher than susceptible for ciprofloxacin (MICs, 0.125 to 0.25 microgram/ml) and ofloxacin (MIC, 0.5 microgram/ml). The diameters of zones of inhibition for these strains ranged from 31 to 39 mm for ciprofloxacin to 28 to 35 mm for ofloxacin. The persistence of these strains over an 18-month period supports the need for routine sentinel surveillance and monitoring of gonococcal isolates, particularly posttreatment isolates, for resistance to quinolones when these agents are used for the primary therapy of uncomplicated gonorrhea.

Emerging in vitro resistance to quinolones in penicillinase-producing Neisseria gonorrhoeae strains in Hawaii.

The susceptibilities of 37 penicillinase-producing strains of Neisseria gonorrhoeae (PPNG), isolated in Hawaii from December 1991 through January 1994, were determined to ciprofloxacin and ofloxacin, fluoroquinolone agents currently recommended by the Centers for Disease Control and Prevention as alternative regimens for the treatment of uncomplicated gonorrhea. Nine isolates (24.3%) exhibited decreased susceptibilities (MICs, > or = 0.06 microgram/ml) to ciprofloxacin and ofloxacin. Ciprofloxacin MICs for three isolates (8.1%) were 2.0 micrograms/ml; these isolates belonged to the auxotype/serovar class Pro/IB-7 and possessed the 3.2-MDa beta-lactamase and the 24.5-MDa conjugative plasmids. Six strains for which ciprofloxacin MICs were 0.06 to 0.125 microgram/ml belonged to a variety of gonococcal phenotypes. Strains for which ciprofloxacin MICs were 2.0 micrograms/ml were isolated from persons who had traveled to, or were sexual contacts of persons who had recently traveled to, Southeast Asia. Persons infected with these isolates had been treated with ceftriaxone (250 mg intramuscularly, single dose); therefore, none of these cases were associated with clinical failure following the use of fluoroquinolone therapy. Further studies are needed to confirm the clinical and public health significance of increased in vitro resistance to ciprofloxacin and ofloxacin in N. gonorrhoeae.