改良皮肤癣菌培养基在甲真菌病诊断中的应用

目的 采用改良皮肤癣菌试验培养基（改良DTM）检测甲真菌病临床标本，并与皮肤癣菌试验培养基（DTM）比较，以评价其临床实用性。方法 收集临床拟诊甲真菌病的标本，分别接种于改良DTM、DTM、含放线菌酮及氯霉素的沙氏培养基（SCCA）和含氯霉素的沙氏培养基（SCA）；记录菌株的开始生长时间、培养基开始变色时间及开始变色时菌落的直径。以专业真菌实验室的鉴定结果为金标准，将DTM和改良DTM的结果与之比较。结果 ①改良DTM、DTM、SCCA的分离率、菌种的生长速度及形态无显著差异。②所有分离的皮肤癣菌均能使两种显色培养基变色，改良DTM的开始变色时间（5.83 ± 0.39 d）早于DTM（7.32 ± 0.41 d），两组比较，t = 2.63，P = 0.01。③大多数分离的非皮肤癣菌也能使两种培养基变色，以开始变色时菌落的直径大小（≥5 mm）为非皮肤癣菌和皮肤癣菌的鉴别点，与金标准有高度的一致性。结论 DTM和改良DTM比传统的鉴定方法结果报告时间提前1周左右，改良培养基的配方较DTM经济，肉眼观察其开始变色时间早于DTM，值得进一步的深入研究。

Application of modified dermatophyte test medium in the diagnosis of onychomycosis

Objective To evaluate the performance of modified dermatophyte test medium （DTM） compared with conventional DTM in the diagnosis of onychomycosis. Methods Nail samples were collected from patients with suspicious onychopathy, and inoculated into modified DTM, DTM, Sabouraud dextrose agar fortified with cycloheximide and chloromycetin （SCCA） and Sabouraud dextrose agar fortified with chloromycetin （SCA） respectively. The initial time of fungal growth and of discoloration of medium, as well as the colony diameter at the beginning of discoloration, were documented. All the results were compared with those from a reference mycologic laboratory. Results The fungal isolation rate, growth speed and colonial appearance were of no difference among modified DTM, DTM and SCCA. All isolates of dermatophyte could alter the color of both modified DTM and DTM. The time needed for discol-oration was shorter in modified DTM than in DTM （5.83 ± 0.39 days vs. 7.32 ± 0.41 days, t = 2.63, P = 0.01）. Although most isolates of nondermatophyte could also produce a discoloration, they could be distin-guished from dermatophytes by colony diameters at the beginning of discoloration （≥5 mm）, and the differentiation results according to this criterion were in a good agreement with those from a reference mycology laboratory. Conclusions Compared to conventional methods, DTM and modified DTM result in a more rapid identification （by 7 days）. Compared to DTM, modified DTM is more economical, and results in an earlier color change. However, further research is needed.