Surgical site infections at the National Cancer Institute in Mexico: A case-control study

Objectives: To quantify the surgical infection rate and to identify risk fa ctors associated with surgical site infection. Methods: We conducted a case-control study of all surgical patients between January 1, 1993, and June 30, 1994. The frequency of surgical site infecti on per 100 surgeries was calculated. The odds ratio (OR) was estimated by u sing logistic regression analysis. Setting: A 130-bed tertiary-care teaching hospital for adult patients with cancer. Results: The study followed 3372 surgeries. Three hundred thirteen patients had a surgical site infection (rate per 100 surgeries: 9.30). The risk fac tors associated with surgical site infection were diabetes mellitus (OR = 2 .5, 95% confidence interval [CI] = 1.27-4.91), obesity (OR = 1.76, 95% CI = 1.14-2.7), presence of surgical drains for >5 and <16 days (OR = 1.84, 95% CI = 1.02-3.31), and presence of surgical drains for greater than or equal to 16 days (OR = 2.14, 95% CI = 1.0-4.6). The bacteria most frequently iso lated were Escherichia coli 38 (21.8% of the total of microorganisms found) , Pseudomonas sp 22 (12.6%), Staphylococcus aureus 16 (9.2%), and coagulase -negative Staphylococcus 25 (13.6%). The coexistence of other nosocomial in fections was greater among the casts (OR = 1.8, 95% CI = 1.1-3.1) than in t he control group. Conclusions: The surgical site infection rate in our hospital is slightly h igher than the rates reported for general hospitals. The risk factors assoc iated with surgical site infection are similar to those previously reported . Diabetes mellitus, obesity, and prolonged presence of a surgical drain in creased the risk of infection.