Perioperative use of cefazolin ameliorates postoperative cognitive dysfunction but induces gut inflammation in mice

Emerging evidence indicates that long-time use of multiple antibiotics can induce cognitive dysfunction via gut dysbiosis. Cefazolin is often used for 3 to 5 days to prevent perioperative infection. This study is to detect the impact of perioperative use of cefazolin on inflammatory responses and postoperative cognition.

The anti-inflammatory effect of cefazolin was determined in mouse C8-B4 microglial cells treated with lipopolysaccharide (LPS). Interleukin (IL)-6 and IL-1β at 6 and 24 h after LPS treatment were detected. Six- to 8-week-old CD-1 mice were subjected to laparotomy. Cefazolin at 300 mg/kg was injected intraperitoneally 1 h before surgery and then once per day for 5 days after surgery. Their learning and memory were assessed by Barnes maze and fear conditioning tests which started 1 week after the surgery. The brain and colon were harvested 24 h and 6 days after surgery to determine inflammatory cytokines. The colon and its luminal contents were harvested 6 and 19 days after surgery for the determination of bacteria flora. Cefazolin concentrations in the serum and brain were measured 0.5, 1, and 2 h after cefazolin injection.

IL-6 and IL-1β levels were decreased by 250 μg/ml cefazolin in the LPS-stimulated C8-B4 cells. Laparotomy increased the time for mice to identify the target hole in the Barnes maze on day 1 and day 8 after training sessions and reduced context-related freezing behavior in fear conditioning test. Cefazolin attenuated these surgical effects but reduced context-related freezing behavior in mice without surgery. IL-6 in the hippocampus and cerebral cortex, IL-1β in the cerebral cortex, and IL-6 and IL-1β in the serum and colon were increased 24 h after laparotomy. Cefazolin attenuated these effects. Cefazolin treatment for 5 days in mice without surgery induced colon dysbiosis and increased IL-6 and IL-1β in the colon and IL-1β in the cerebral cortex. Colon dysbiosis disappeared in mice treated with cefazolin alone but persisted in mice with surgery and cefazolin 19 days after surgery. High cefazolin concentrations in the serum but not in the brain were detected after cefazolin injection.

These results suggest that cefazolin has a direct anti-inflammatory effect and can attenuate surgery-induced postoperative memory and learning impairment in mice. Cefazolin alone may induce cognitive dysfunction possibly by transient gut dysbiosis in mice without surgery.