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.

Treatment of chancroid with spectinomycin or co-trimoxazole.

Chancroid, the third most prevalent venereal disease in Thailand, was treated with a single 2-gm dose of spectinomycin, or two tablets of co-trimoxazole (trimethoprim-sulfamethoxazole) twice daily for seven days. The differences in cure rates between the two groups were statistically significant. The chancroidal ulcers were cured in 93.7% of 175 patients treated with spectinomycin, and in 48.2% of 168 co-trimoxazole-treated patients (P less than 0.01). The in vitro susceptibility of Haemophilus ducreyi to spectinomycin was 4 to 16 micrograms/ml and to co-trimoxazole 32 micrograms/ml or higher. Thus we found that a single-dose regimen of spectinomycin was significantly more effective than the standard seven-day regimen of co-trimoxazole for the treatment of chancroid.

Clinical and microbiological efficacy of a single dose of norfloxacin in the treatment of chancroid.

Forty-one men with a clinically and bacteriologically verified diagnosis of chancroid were given a single dose of 800 mg of norfloxacin and were examined clinically and bacteriologically four, seven and 14 days after treatment. Five patients were excluded from evaluation of efficacy due to concomitant infections or incomplete follow-up. Of the remaining 36 patients, 34 were cured and culture negative at follow-up controls. Another 15 men with culture-negative ulcers treated with 800 mg of norfloxacin as a single dose, were all cured clinically. The high cure rate and the good tolerability make norfloxacin a convenient and cheap alternative to intramuscular single dose therapy of chancroid.

Efficacy of ofloxacin in uncomplicated gonorrhoea.

A randomised double blind trial comparing single oral dose therapy with 200 mg and 400 mg of ofloxacin, respectively was conducted at the Bangrak Hospital, Bangkok during the period December 6, 1985 to January 24, 1986. We treated 234 male patients diagnosed as having uncomplicated gonococcal urethritis with ofloxacin. Ofloxacin, at a single dose of 200 mg or 400 mg, was given to each of them. Fourteen patients were excluded for efficacy assessment. There were 223 patients left for safety assessment. The cure rates were 100% in both groups. Among 233 isolates tested, 48.5% were penicillinase producing Neisseria gonorrhoeae. The range of minimum inhibitory concentrations of ofloxacin was 0.008 to 0.063 mg/l. No adverse drug experiences were reported.