Welch D F, Kelly M T
Antimicrob Agents Chemother. 1979 Jun;15(6):754-7. doi: 10.1128/AAC.15.6.754.
A total of 24 strains of the Mycobacterium fortuitum complex were tested for susceptibility to antimicrobial agents by the disk diffusion and agar dilution techniques. By comparing zones of inhibition obtained with the disk diffusion technique with results of minimal inhibitory concentration determinations, it was shown that disk diffusion results could predict in vitro susceptibility to selected antimicrobial agents. All of 17 strains of M. fortuitum were susceptible to </=1 mug of amikacin per ml. The corresponding average zone of inhibition around a 10-mug amikacin disk was 37 mm. Seven M. chelonei strains were more resistant to amikacin, with minimal inhibitory concentrations ranging from 1 to 32 mug/ml, and the corresponding average zone size was 21 mm. Susceptibility of both M. fortuitum and M. chelonei to tetracycline was variable and none of the M. chelonei strains was inhibited by polymyxin B, whereas M. fortuitum strains consistently had zones of inhibition around the polymyxin disk. It appears that identification to species of the M. fortuitum complex may be of importance with regard to antibiotic susceptibility. Separation of M. fortuitum and M. chelonei was readily accomplished in the present study by the nitrate reduction and 3-day arylsulfatase tests.
采用纸片扩散法和琼脂稀释法对24株偶然分枝杆菌复合群菌株进行了抗菌药物敏感性测试。通过将纸片扩散法获得的抑菌圈与最低抑菌浓度测定结果进行比较，结果表明纸片扩散法结果能够预测所选抗菌药物的体外敏感性。17株偶然分枝杆菌均对每毫升≤1微克的阿米卡星敏感。在含10微克阿米卡星的纸片周围，相应的平均抑菌圈直径为37毫米。7株龟分枝杆菌对阿米卡星的耐药性更强，最低抑菌浓度范围为1至32微克/毫升，相应的平均抑菌圈大小为21毫米。偶然分枝杆菌和龟分枝杆菌对四环素的敏感性各不相同，龟分枝杆菌菌株均未被多粘菌素B抑制，而偶然分枝杆菌菌株在多粘菌素纸片周围始终有抑菌圈。就抗生素敏感性而言，偶然分枝杆菌复合群的菌种鉴定似乎很重要。在本研究中，通过硝酸盐还原试验和3天芳基硫酸酯酶试验，很容易将偶然分枝杆菌和龟分枝杆菌区分开来。
