[Influence of broad-spectrum antibiotics on the gut microflora in sepsis in rats].

OBJECTIVE

To study the influence of broad-spectrum antibiotics on intestinal microecology in septic rats.

METHODS

Fifty-six Sprague-Dawley (SD) rats were randomly divided into normal control, burn and sepsis group. Rats in the latter two groups received 30% total body surface area (TBSA) III degree burns on back followed by an injection of endotoxin in a dose of 20 mg/kg 24 hours later. The animals in sepsis group were treated with intraperitoneal injection of ceftriaxone 12 hours after the endotoxin challenge in a dose of 60 mg/kg, and it was repeated 12 hours later. Another group of rats received burn injury only. Eight rats in burn group and sepsis group were sacrificed before ceftriaxone treatment, 3 days and 9 days after the treatment, respectively. The gastric, intestinal and colonic contents were collected for bacterial cultures and species determination.

RESULTS

The influence of burn injury on the number and species of gut bacteria was not obvious. The addition of endotoxin could markedly increase the number of enteric bacilli in small intestine and colon (both P < 0.01), but not in stomach. However, the number of enteric bacilli was sharply decreased in intestine and colon after ceftriaxone treatment (all P < 0.01). Furthermore, the ratio of cocci to bacilli was seriously inverted in intestine and colon after ceftriaxone treatment, though burn injury followed by endotoxin had dramatically raise the ratio of cocci to bacilli in intestine and colon.It also produce a loss of anaerobic bacteria in colon, though the difference in number was not statistically significant.

CONCLUSION

Broad-spectrum antibiotics could decrease the amount of enteric bacilli, making enterococci to be the predominant microbial flora in gut.