Rokosz A, Rouyan G S, Meisel-Mikołajczyk F
Zakład Bakteriologii Klinicznej AM w Warszawie.
Med Dosw Mikrobiol. 1997;49(3-4):153-9.
Four B. fragilis strains were examined: one nonenterotoxigenic (NTBF) and three producing enterotoxin (ETBF). The growth of cultures was determined and enterotoxin, which is released to the culture medium during growth of strains, was detected. BHI broth and BHI broth with addition of subinhibitory doses (sub-MIC) of clindamycin were applied. Bacterial cultures were incubated at 37 degrees C for 48 hours. After 4, 8, 16, 24, 48 hours of cultivation, samples of bacterial cultures were collected and the optical density was measured. Then the samples were centrifuged, supernatants were filtered through 0.45 micron filters and concentrated three times with 5000 D ultrafilters. Prepared samples were kept frozen at -70 degrees C until used. The titre of enterotoxin in samples was determined on human colon adenocarcinoma cell line HT 29/C1. Neutralization assay was performed with culture filtrates, which were enterotoxin-positive and with rabbit anti-enterotoxin serum. The results of the experiments indicate that enterotoxin is detected after 16 hours of incubation of ETBF strains. Clindamycin at subinhibitory concentrations (sub-MIC) inhibits the growth of B. fragilis cultures. The antibiotic causes also delay and decrease in enterotoxin production by ETBF strains.
对4株脆弱拟杆菌菌株进行了检测：1株非产肠毒素型（NTBF）和3株产肠毒素型（ETBF）。测定了培养物的生长情况，并检测了菌株生长过程中释放到培养基中的肠毒素。使用了脑心浸液肉汤（BHI肉汤）以及添加了亚抑菌剂量（亚最小抑菌浓度，sub-MIC）克林霉素的BHI肉汤。将细菌培养物在37℃下孵育48小时。在培养4、8、16、24、48小时后，收集细菌培养物样本并测量光密度。然后将样本离心，上清液通过0.45微米滤器过滤，并用5000D超滤器浓缩3倍。制备好的样本保存在-70℃直至使用。在人结肠腺癌细胞系HT 29/C1上测定样本中肠毒素的滴度。用肠毒素呈阳性的培养滤液和兔抗肠毒素血清进行中和试验。实验结果表明，ETBF菌株孵育16小时后可检测到肠毒素。亚抑菌浓度（亚-MIC）的克林霉素可抑制脆弱拟杆菌培养物的生长。该抗生素还会导致ETBF菌株产生肠毒素的延迟和减少。
