Comparison of E-test with agar dilution methods in testing susceptibility of N. gonorrhoeae to azithromycin.
Sex Transm Dis
; 24(5): 257-60, 1997 May.
Article
em En
| MEDLINE
| ID: mdl-9153733
ABSTRACT
BACKGROUND AND OBJECTIVES:
The antimicrobial susceptibility pattern of Neisseria gonorrhoeae varies from one country to another and may also change with time. To monitor these variations and changes, it is desirable to have a method that is simple and reproducible. This study was undertaken to determine the in vitro susceptibility of N. gonorrhoeae to azithromycin and to assess the reliability of results obtained using E-test methodology for determination of the minimum inhibitory concentration (MIC) of azithromycin. STUDYDESIGN:
The MICs for 135 clinical isolates of N. gonorrhoeae were determined by a modified Kirby-Bauer method recommended by the National Committee for Clinical Laboratory Standards against penicillin, cefuroxime, ceftriaxone, norfloxacin, tetracycline, kanamycin, spectinomycin, and azithromycin. The MIC of azithromycin was determined by both the E-test and agar dilution method. All tests were done simultaneously.RESULTS:
The MIC of azithromycin to all 135 isolates ranged from 0.078 to 0.25 microgram/ml with the agar dilution method and from 0.016 to 0.50 microgram/ml with the E-test. The MIC50 and MIC90 of azithromycin were 0.064 microgram/ml and 0.125 microgram/ml, respectively, by the agar dilution method, whereas they are slightly higher by the E-test method. Seventy-six of the isolates were beta-lactamase producers and 69 were high-level tetracycline-resistant N. gonorrhoeae. There was no difference in the MIC50 and MIC90 of azithromycin in these groups of isolates. The percentage agreement within the acceptable +/-1 log2 dilution difference between MICs obtained by E-test and those obtained by the agar dilution method was 97.8%.CONCLUSIONS:
Azithromycin has a very good in vitro antigonococcal activity, and the E-test is a reliable method to determine the MIC of azithromycin against N. gonorrhoeae.ABSTRACT
PIP A single dose of a new antibiotic, azithromycin, has been shown to be effective in the treatment of uncomplicated Neisseria gonorrhoeae. A clinical study was conducted to assess the in vitro susceptibility of N gonorrhoeae to azithromycin and compare the reliability of results obtained using the new E-test methodology for determination of the minimum inhibitory concentration (MIC) of antibiotic with those obtained through the standard agar dilution method. 135 clinical isolates of N gonorrhoeae were obtained from patients attending hospital-based sexually transmitted disease clinics in five geographic locations in Malaysia. 76 of the isolates were penicillinase-producing N gonorrhoeae and 69 were high-level tetracycline-resistant N gonorrhoeae. All isolates were susceptible to azithromycin based on the susceptible MIC breakpoint of 2.0 mcg/ml. The MICs ranged from 0.0078-0.25 mcg/ml by agar dilution method and from 0.016-0.50 mcg/ml by E-test. Agreement between these two methods was 97.8%. The single-dose regime and good antigonococcal and antichlamydial activity of azithromycin make this antibiotic a suitable treatment choice. Moreover, the findings of this study suggest that the simpler, faster E-test is as reliable as the agar dilution method. Given the tendency of the antimicrobial susceptibility pattern of N gonorrhoeae to change rapidly, it is important to monitor MICs to detect the emergence of resistance.
Palavras-chave
Antibiotics--therapeutic use; Asia; Clinical Research; Developing Countries; Diseases; Drugs; Examinations And Diagnoses; Gonorrhea; Infections; Laboratory Examinations And Diagnoses; Laboratory Procedures; Malaysia; Measurement; Reliability; Reproductive Tract Infections; Research Methodology; Research Report; Sexually Transmitted Diseases; Southeastern Asia; Treatment
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Base de dados:
MEDLINE
Assunto principal:
Testes de Sensibilidade Microbiana
/
Azitromicina
/
Antibacterianos
/
Neisseria gonorrhoeae
Tipo de estudo:
Guideline
Limite:
Humans
País como assunto:
Asia
Idioma:
En
Ano de publicação:
1997
Tipo de documento:
Article