Risk factors for extended spectrum β-lactamase-producing Escherichia coli versus susceptible E. coli in surgical site infections among cancer patients in Mexico.

BACKGROUND

Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli are of increasing concern as a cause of healthcare-associated infections.

STUDY

DESIGN

Using a matched case-control design, demographics, antibiotic use, and relevant surgical data were obtained for 173 cases (ESBL E. coli surgical site infections, [SSI]) and 173 controls (antibiotic-susceptible E. coli SSI) in an oncology hospital in Mexico City. Conditional logistic regression modeling was used to calculate odds ratios (OR).

RESULTS

The mean age of patients was 53.6 years, 214 (62%) were female. Demographics and comorbidities were similar between groups. Although antibiotic prophylaxis was common among both cases and controls (84% and 89%), more than one-half of cases (53%) were given prophylaxis outside the recommended window or were exposed for more than 24 h in comparison to 29% of controls. Patients who received untimely (OR=3.13, 95% confidence interval [CI] 1.5-6.4) and discontinued inappropriately (OR 6.38, 95% CI=2.5-16.2) prophylaxis were more likely to develop an ESBL SSI. In addition, patients with an organ/space infection compared with superficial had a higher rate of a resistant infection (OR 4.2, 95% CI 1.3-13.9). Among patients not given timely or appropriately discontinued prophylaxis, post-operative cephalosporin use (OR 3.3, 95% CI 1.4-7.7) was associated with ESBL E. coli SSIs.

CONCLUSIONS

The appropriate timing and duration of perioperative antimicrobial prophylaxis were associated with lower risk of ESBL E. coli in SSIs. Even though compliance to antimicrobial prophylaxis guidelines is of the utmost importance, reduced exposure to cephalosporins may also potentially decrease the risk of ESBL SSI.