Laboratory detection of ciprofloxacin resistant Neisseria gonorrhoeae

Antimicrobial susceptibility of Neisseria gonorrhoeae strains isolated in 2004-2006 in Bangui, Central African Republic; Yaoundé, Cameroon; Antananarivo, Madagascar; and Ho Chi Minh Ville and Nha Trang, Vietnam

GOAL

To investigate the in vitro antimicrobial susceptibility of Neisseria gonorrhoeae strains isolated in 2004 and 2005 in Bangui, Central African Republic; Yaoundé, Cameroon; Antananarivo, Madagascar; and Ho Chi Minh Ville and Nha Trang, Vietnam.

STUDY DESIGN

Antimicrobial susceptibility testing was performed by both disk diffusion and agar dilution methods according to Clinical and Laboratory Standards Institute (CLSI) recommendations. Minimum inhibitory concentrations (MICs) to 5 antimicrobials (penicillin G, ceftriaxone, ciprofloxacin, spectinomycin, and tetracycline) were determined when feasible. Penicillinase-producing N. gonorrhoeae (PPNG) was analyzed by the paper acidometric method (nitrocefin test).

RESULTS

Thirty N. gonorrhoeae isolates from Bangui could be studied, 79 from Yaoundé, 126 from Antananarivo, 56 from Nha Trang, and 126 from Ho Chi Minh Ville in 2004 and 2005. Unfortunately, because of problems of electricity supply, no strains could be recovered for the determination of MICs in Yaoundé, and only 68 strains could be tested in Antananarivo and 121 in Ho Chi Minh Ville. Patterns of resistance were similar in Antananarivo, Bangui, and Yaoundé but different from those observed in Vietnam. Ciprofloxacin was highly effective in Africa, but nearly all strains in Vietnam were resistant to this drug. Overall, ceftriaxon and spectinomycin were the best antibiotics, with one strain resistant to spectinomycin in Antananrivo and one strain resistant to ceftriaxon in Ho Chi Minh Ville.

CONCLUSIONS

Ciprofloxacin remains highly efficient in Madagascar and Central Africa, ceftriaxone and spectinomycin should be used as the first-line antimicrobial agents in treating gonorrhea in Vietnam.

Fluoroquinolone resistance in Neisseria gonorrhoeae

Fluoroquinolones and broad-spectrum cephalosporins are the most effective antimicrobial agents for the treatment of gonorrhea. However, clinically significant resistance to fluoroquinolones has emerged in Neisseria gonorrhoeae. Fluoroquinolone-resistant strains account for approximately 10% of all gonococcal strains in Hong Kong and the Republic of the Philippines. As many as 50% of strains from some Far Eastern countries exhibit decreased susceptibility (intermediate resistance) to fluoroquinolones. Strains with intermediate resistance and clinically significant resistance are being isolated sporadically in North America, where resistant strains have been associated with an outbreak and with failure of infections to respond to treatment with doses of ciprofloxacin and ofloxacin recommended by the Centers for Disease Control and Prevention; strains exhibiting decreased susceptibility to these agents are endemic in at least one metropolitan area. Monitoring for fluoroquinolone resistance is now critical for ensuring adequate treatment of infections with resistant strains and for maximizing the time during which fluoroquinolones may be used to treat gonorrhea.

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]).

Quinolones in sexually transmitted diseases

The role of quinolones in the treatment of sexually transmitted diseases is assessed. Little is known of their activity against Treponema pallidum. These compounds are all highly active against Neisseria gonorrhoeae, and have produced good in vivo results with a single dose. Only the more recent compounds show useful antichlamydial activity in vitro. Clinical trials with ofloxacin demonstrate the efficacy of a single daily dose for 7 days for chlamydial genital infection in men and women. Results for treatment of bacterial vaginosis have so far been disappointing. Ciprofloxacin and fleroxacin are effective for chancroid. The potential for treating pelvic inflammatory disease with new quinolones is discussed.

Antibiotic susceptibility survey of Neisseria gonorrhoeae in Thailand

The antibiotic susceptibilities of Neisseria gonorrhoeae isolates obtained from patients attending sexually transmitted disease clinics in Cholburi and Bangkok, Thailand, were determined by agar dilution. Some 28.2% of isolates produced beta-lactamase. A total of 97.9% of beta-lactamase-positive and 51% of beta-lactamase-negative isolates tested were resistant to penicillin (MICs, greater than or equal to 2 micrograms/ml), 70% of isolates tested were resistant to tetracycline (MICs, greater than or equal to 2 micrograms/ml), and 91% of isolates tested were susceptible to spectinomycin (MICs, less than or equal to 64 micrograms/ml). The MICs for 90% of isolates for the other drugs tested were 2 micrograms/ml for erythromycin, 2 micrograms/ml for cefoxitin, 1 micrograms/ml for cefuroxime, 0.125 micrograms/ml for cefpodoxime, 0.06 micrograms/ml for cefotaxime, 0.25 micrograms/ml for ceftazidime, 0.03 micrograms/ml for ceftizoxime, 0.03 micrograms/ml for ceftriaxone, 0.03 micrograms/ml for cefixime, 0.06 micrograms/ml for aztreonam, 0.008 micrograms/ml for ciprofloxacin, 0.125 micrograms/ml for norfloxacin, and 0.075 micrograms/ml for ofloxacin. Fewer than 1.5% of isolates were resistant to the extended-spectrum cephalosporins tested. Some 0.3% or fewer isolates were resistant to broad-spectrum cephalosporins, fluoroquinolones, or the monobactam aztreonam. Antibiotic resistance among N. gonorrhoeae isolates from Cholburi and Bangkok in May 1990 appeared to be primarily limited to penicillin and tetracycline, which are no longer used to control gonorrhea. Spectinomycin, which has been in general use against gonorrhea in Thailand since 1983, has dwindling utility, with resistance at a level of 8.9%.

Examination of spinal cord in diseases of the craniocervical junction and high cervical spine

A simple necropsy technique for the removal of the craniocervical junction was devised: a relatively small specimen comprising part of the clivus, the foramen magnum, and cervical vertebral canal is removed in one piece with the medulla and spinal cord inside, and examined systematically after fixation. This method, used in a series of patients with chronic craniocervical instability, allows both good clinicopathological correlations to be made and histological changes in the lower medulla or upper cervical cord segments to be related to sites of extrinsic compression.