Objective To investigate the types of pathogenic bacteria

clinical characteristics and risk factors of surgical site infection（SSI）following colorectal cancer surgery

which may provide a theoretical basis for the diagnosis and treatment of postoperative SSI.Methods A total of 160 patients who underwent colorectal cancer radical resection between December 2014 and December 2016 in a Hubei hospital were included in our study.The number of patients who experienced SSI was counted and samples were collected from the infection site.An automatic microbial identification system was used to examine the types of pathogenic bacteria.And Logistic regression analysis was performed to identify the risk factors of SSI.Results 38 patients（23.75%）experienced SSI after surgery;the most common infection site was superficial incision（30 patients

78.95%）

followed by deep incision（6 patients

15.79%）and organ/space（2 patients

5.26%）.A total of 38 Gram-negative strains were detected

and the detection rates of E.coli

P.aeruginosa

K.pneumonia

E.aerogenes

and A.baumannii were 68.42%

13.16%

10.53%

5.26%

and 2.63%

respectively;10 Gram-positive strains were identified

and the detection rates of S.epidermidis

S.aureus

E.faecium

and E.faecalis were 40.00%

30.00%

20.00%

and 10.00%

respectively.Logistic regression analysis showed that

the duration of surgery≥4 h and body mass index（BMI）≥24 kg/m2 were risk factors for SSI（P<0.05）.Conclusion The major risk factors for SSI after colorectal cancer surgery include the duration of surgery and BMI.Therefore

preventive measures should be administered to avoid SSI in patients with such risk factors.