VAC对猪爆炸伤感染创面细菌数和G^+/G^-比例的影响

Effect of vacuum-assisted closure on bacteria load and G^+ to G^- bacteria ratio in pig's infected soft tissue blast injury

目的:观察封闭负压引流技术(VAC)对猪皮肤软组织爆炸伤感染创面细菌数和G+/G-比例的影响,为将该技术应用于爆炸伤的临床治疗提供实验依据.方法:用电雷管在4只15~20kg的小白家猪双侧肩胛及双侧臀部造成16个爆炸伤创面,随机分为对照组和治疗组.两组创面伤后前2d不做任何治疗,以造成创面感染.伤后3d,对照组常规换药,治疗组采用-15kPa负压的VAC治疗.于治疗前和治疗后1,3,6,9,14和19d取创面活组织,匀浆后将匀浆液倍比稀释,在血琼脂糖平板上37℃孵育24h,进行细菌计数,并对每份标本的200个菌落进行革兰氏染色,计算革兰氏阳性菌的比例.结果:治疗前创面中的细菌数高达107,VAC治疗后3d,治疗组细菌数迅速下降到(1.91±0.245)×105cfu/g,治疗后6d降至(0.51±0.120)×105cfu/g.对照组创面内的细菌数下降缓慢,在治疗后9d降至(19.54±3.67)×105cfu/g;治疗后19d仍高达(3.26±0.83)×105cfu/g,治疗后1~19d,治疗组创面内的细菌数比对照组明显减少(P<0.01).治疗前两组创面革兰氏阳性(G+)细菌比例在31%~36%之间;治疗后治疗组创面革兰氏阳性细菌比例逐渐增高,6d增至(55.58±2.98)%,其后维持在较高水平;对照组中G+细菌的比例在治疗后1~19d始终维持在30%~40%,明显较治疗组低(P<0.01).结论:与对照组相比,VAC能有效地减少猪皮肤软组织爆炸伤感染创面的细菌数,且能降低创面内革兰氏阴性细菌的比例.

AIM： To observe the effect of vacuum-assisted closure （VAC） on the bacteria load and the ratio of G^＋ bacteria to G^- bacteria in pig＇s infected soft tissue blast injury. METHODS： Sixteen blast wounds, created by explosion of a specific type of electric detonators which were fixed at 1 cm over the skin of the shoulders and hips of 4 small white domestic pigs （ 15 -20） kg, were divided into 2 groups： the control group treated with conventional dressing change, and the experimental group treated with VAC at - 15 kPa. All wounds were left untreated until the 3rd day after explosion and subsequently were infected. Tissue specimens, collected from the wounds before treatment and at different time pints （1, 3, 6, 9, 14, and 19 d） after treatment, were weighed and homogenized, and each specimen＇s homogenate, after diluted, was plated on blood agar and incubated at 37℃ for 24 h. After the number of bacterial colonies was counted, 200 out of the bacterial colonies of each specimen were processed for conventional Gram-staining and the rate of gram- positive bacteria was calculated. RESULTS： Before treatment, the wound bacteria load of the 2 groups was up to about 3 × 10^7 cfu/g; it decreased to （ 1.91 ± 0. 245 ） × 10^5 cfu/g at day 3 after treatment in experimental group, and to （0.51 ±0. 120） × 10s cfu/g at day 6; it decreased more slowly in control group to （ 19.54 ± 3.67 ） × 10^5 cfu/g at day 9 after treatment and to （3.26 ± 0.83 ） × 10^5 cfu/g at day 19 after treatment. Mean- while, the rate of Gram-positive bacteria was about 31% -36% of total bacteria in all wounds before treatment; that of experimental group increased to （55.58 ±2.98）% at day 6 after treatment and maintained at a high level thereafter; that of control group fluctuated between 30% and 40% from 1 to 19 d after injury. Compared with control group, experimental group had less bacteria and higher rate of gram-positive bacteria （ P 〈 0.01 ） from 1 to 19 d after treatment. CONCLUSION： VAC can significantly decrease the bacteria load and the rate of Gram-negative bacteria in pig＇s infected soft tissue blast injury.