Impact of the contamination time by Escherichia coli on biofilm formation in surgical instruments

ABSTRACT Objectives: to evaluate the microbial load and adherence of Escherichia coli in different areas of the surgical instrument surface exposed to experimental contamination over time. Methods: experimental study in which fragments of crile forceps (serrated, rod and rack) were contaminated by immersion in Tryptic Soy Broth, containing 106 CFU/mL of E. coli, for 1, 2, 4, 6, 8, 12 and 24 hours. Microbial load and bacterial adherence were evaluated using microbiological culture and scanning electron microscopy, respectively. Results: there was an increase in the microbial load on the surgical instrument, proportional to the contamination interval, ranging from 102 after 1 hour to 105 CFU/cm2 in 24 hours. The presence of exopolysaccharide was detected after two hours of contamination. Conclusions: microbial load and adhesion of E. coli increased over time, reaching 105 CFU/cm2 after 24 hours of contamination, starting biofilm formation after two hours.

【摘要】
研究目的：评估实验性污染后不同时长下，手术器械表面不同区域的大肠埃希菌（Escherichia coli）微生物载量与黏附情况。
研究方法：本研究为实验研究，将克氏止血钳（Crile forceps）的齿部、杆部及钳锁部样本置于含10^6 CFU/mL大肠埃希菌的胰蛋白胨大豆肉汤（Tryptic Soy Broth）中浸泡，分别于1、2、4、6、8、12及24小时取样检测。采用微生物培养法检测微生物载量，扫描电子显微镜（scanning electron microscopy）观察细菌黏附状况。
研究结果：手术器械表面的微生物载量随污染时长呈正比增长，从1小时后的10² CFU/cm²升至24小时后的10^5 CFU/cm²；污染2小时后即可检测到胞外多糖的存在。
研究结论：大肠埃希菌的微生物载量与黏附能力随时间延长而升高，污染24小时后微生物载量可达10^5 CFU/cm²，且于污染2小时后即启动生物膜形成。