Borchardt K A, Li Z, Zhang M Z, Shing H
CAMT, San Francisco State University, CA 94132, USA.
Genitourin Med. 1996 Apr;72(2):132-5. doi: 10.1136/sti.72.2.132.
An efficient anaerobic culture system, the InPouch TV test, was used to determine the susceptibility of Trichomonas vaginalis to metronidazole. Glacial acetic acid was employed as a solvent for metronidazole.
T vaginalis isolates were cultured from 16 symptomatic female patients. The 11 who responded to oral metronidazole, 250 mg tid for 7 days, were considered as having sensitive trichomonads; the 5 who remained infected after treatment were considered to have resistant organisms. All isolates were cultured for minimum lethal concentrations (MLC). Metronidazole was added to a series of pouches; two-fold dilution of the most concentrated was 50 micrograms/ml and the least was 0.4 micrograms/ml. The inoculum of viable trichomonads was 1 x 105/ml in each pouch. Pouches were incubated at 37 degrees C for 48 h, examined microscopically for motile trichomonads, and then 0.5 ml was subcultured to drug free pouches. After 5 days incubation at 37 degrees C, each subculture and culture were examined microscopically for viable trichomonads.
Eleven isolates of T vaginalis from patients responding to metronidazole treatment had MLC between 0.4 to 3.1 micrograms/ml. The MLC from the 5 treatment failure patients were between 12.5 to 50 micrograms/ml.
For the 16 patients in this study, the MLC values determined with the InPouch TV test differentiated between infection caused by metronidazole sensitive and resistant trichomonads. The mean MLC of clinically resistant isolates was approximately eleven fold higher than the mean MLC of clinically sensitive isolates (15 micrograms/ml vs 1.32 micrograms/ml). There was a significant difference between clinically resistant and sensitive isolates (t = 5.47, p < 0.0005). This study suggests that the InPouch TV test could be used for distinguishing between metronidazole resistant and sensitive isolates.
采用一种高效的厌氧培养系统——InPouch TV试验，来测定阴道毛滴虫对甲硝唑的敏感性。使用冰醋酸作为甲硝唑的溶剂。
从16名有症状的女性患者中分离培养阴道毛滴虫。11名对口服甲硝唑（250毫克，每日三次，共7天）有反应的患者被认为感染的是敏感滴虫；5名治疗后仍感染的患者被认为感染的是耐药菌。所有分离株均培养以确定最低致死浓度（MLC）。将甲硝唑添加到一系列培养袋中；最浓溶液的两倍稀释液浓度为50微克/毫升，最稀的为0.4微克/毫升。每个培养袋中活滴虫的接种量为1×10⁵/毫升。将培养袋在37℃下孵育48小时，显微镜检查活动的滴虫，然后将0.5毫升接种到无药的培养袋中。在37℃下孵育5天后，对每个传代培养物和培养物进行显微镜检查以确定活滴虫。
11例对甲硝唑治疗有反应的患者的阴道毛滴虫分离株的MLC在0.4至3.1微克/毫升之间。5例治疗失败患者的MLC在12.5至50微克/毫升之间。
对于本研究中的16名患者，通过InPouch TV试验测定的MLC值区分了由甲硝唑敏感和耐药滴虫引起的感染。临床耐药分离株的平均MLC比临床敏感分离株的平均MLC高约11倍（15微克/毫升对1.32微克/毫升）。临床耐药和敏感分离株之间存在显著差异（t = 5.47，p < 0.0005）。本研究表明，InPouch TV试验可用于区分甲硝唑耐药和敏感分离株。
