犬海水中火器伤细菌感染定量研究

Quantitative study of bacteriological infections in dogs undergoing gunshot wound in seawater

目的定量探讨海水中火器伤伤道组织细菌增殖的变化规律及发生感染的时限,为进一步研究这一特殊环境下火器伤组织清创时机、方法及抗生素应用提供依据。方法将16条犬随机分为海水中致伤组与地面致伤组,海水组14只,地面组2只;于火器伤后0、6、12、24 h进行大体观察及细菌学定量检测。对测得结果进行统计学分析,并建立火器伤组织中细菌增殖动力学模式。结果两组伤犬伤道单位组织中的细菌数均随时间的延长而递增,且海水组同一时间点的细菌数均比地面组高,击伤即时的细菌污染程度较地面组重,6 h时已达感染临界。两组组织中细菌生长的动力学模式可用下式概括: Y(1) = 9.12×10(3+0.247X), Y(2) = 1.35×10(3+0.227X)。式(1)、(2)分别为海水组和地面组火器伤组织中细菌生长的动力学模式,为每克组织中的细菌含量(个/g),X为火器伤伤后时相。根据这一模式,我们计算得到海水组和地面组达到感染临界时所需的时间分别为4.2和8.2 h,海水组达到感染临界状态比地面组提前4 h。结论海水中火器伤较地面火器伤污染重、损伤重,细菌繁殖快,感染出现早,应及早清创、彻底冲洗伤道和及时应用抗生素,这些治疗措施应以在4 h之内完成为宜。

Objective To investigate the changes in bacterial proliferation and the time of infection occurrence in dogs wounded by gunshot in seawater. Method Fourteen canine models of gunshot wound in seawater were established, with another 2 dogs receiving the wound without seawater immersion serving as control. Gross observation and quantitative bacterial analysis were performed at 0, 6, 12 and 24 h after the injury respectively, and two dynamic models for the bacterial growth were set up on the basis of statistical analysis of the results. Results Bacterial quantity in both of the two groups tended to increase with time, but at each time point after the injury, the seawater group had higher bacterial count than the other group. Within 6 h after the injury, the bacterial count reached the critical point for clinical infection in seawater group. The two bacterial growth dynamics models were (1) Y=9.12×10 (3+0.247X) and (2) Y=1.35×10 (3+0.227X) for the seawater group and land group respectively, with the variant X representing time after gunshot injury, and Y the bacterial count per gram tissue. Using the dynamic models, we found that to reach the same bacteria count, the land group needed 4 h more than the seawater group(4.2 h). Conclusions Bacterial proliferation is accelerated in the wounds in seawater to result in earlier infection onset with more severity, suggesting that early debridement within 4 h after the injury, complete washing of the wound and early administration of the antibiotics are necessary for the wound management.