Evidence Corner: Antibiotic Timing to Prevent Caesarean Section Surgical Site Infection

Dear Readers:   Surgical site infection (SSI) increases the duration and costs of postsurgical hospital care and decreases patient quality of life.¹ As the Association for the Advancement of Wound Care (AAWC) Guideline Task Force drafts the next AAWC Guideline on wound infection control, evidence gaps are emerging about indications and timing of perioperative antibiotics to prevent SSI. When does one give which antibiotics to prevent SSI, and for which elective surgery indications? Do the same rules apply to all surgical procedures? Do antibiotic prophylaxis procedures change if a foreign body is introduced during surgery, such as a prosthesis or mesh used to reinforce repairing hernias? What about surgical repair of an infected diabetic foot? Professionals may wonder if guideline recommendations are clinically relevant to wounds in their care unless there is strong direct evidence for the specific indication treated. Though evidence gaps remain for antibiotic prophylaxis usage details for many wounds, recent research provides evidence to inform clinical decisions about antibiotic prophylaxis to prevent SSI for patients undergoing caesarean sections² and tension-free mesh repair of inguinal hernias.³Laura Bolton, PhD, FAPWCA Adjunct Associate Professor Department of Surgery, UMDNJ WOUNDS Editorial Advisory Board Member and Department Editor

Antibiotic Timing to Prevent Caesarean Section Surgical Site Infection

  References: Baaqeel H, Baaqeel R. Timing of administration of prophylactic antibiotics for caesarean section: a systematic review and meta-analysis. BJOG. 2012; doi: 10.1111/1471-0528.12036. [Epub ahead of print]   Rationale: Perioperative prophylactic antibiotics reduce caesarean section infection rates, but their optimal timing remains yet to be clarified.   Objective: Explore maternal and neonatal infectious morbidity in women receiving preoperative compared to intraoperative prophylaxis.   Methods: Medline, Embase, Current Controlled Trials, and Cochrane Central databases were searched from database inception dates to December 2011 for randomized controlled trials (RCTs) comparing a single prophylactic dose of antibiotics administered preoperatively to a single intraoperative dose. Independently extracted RCT characteristics, outcomes, and quality measures were summarized based on the Cochrane tool for risk of bias. Meta-analyses of relative risks (RRs) for maternal and neonatal infectious outcomes were analyzed using a random effects model.   Results: Six trials reporting on 2313 mothers and 2345 newborns qualified for inclusion. Three RCTs were of high quality and unbiased. There may have been several sources of bias in 1 study on 389 subjects. Two more studies on a total of 659 subjects may have had nonblinded evaluation. Two RCTs on 392 mothers were on emergency caesarean sections, the remaining 4 RCTs were on elective caesarean sections. Cefazolin 1 g or 2 g was the antibiotic used on more than 90% of subjects in all trials. Mothers allergic to penicillin received 900 mg of clindamycin. Preoperative administration of prophylactic antibiotics reduced the incidence of maternal endometritis by 41% compared to that of mothers receiving only intraoperative prophylactic antibiotics (P Authors’ Conclusions: Preoperative antibiotics significantly reduce the rate of maternal endometritis following caesarean section compared with only intraoperative antibiotic administration. Lack of similar effects on neonates so delivered should be interpreted with caution as the RCTs were not adequately powered to detect these effects.

Prophylactic Antibiotics for Tension-Free Hernioplasty

  Reference: Li JF, Lai DD, Zhang XD, et al. Meta-analysis of the effectiveness of prophylactic antibiotics in the prevention of postoperative complications after tension-free hernioplasty. Can J Surg. 2012;55(1):27-32. Doi: 10.1503/cjs.018310   Rationale: A prior meta-analysis of elective inguinal hernia repair reported no statistical difference in incision infection rates between groups receiving prophylactic antibiotics and control groups, though subgroup analysis suggested a protective effect in tension-free hernioplasty undetectable due to small sample size. New RCT evidence on patients undergoing tension-free hernioplasty merits an updated review.   Objective: Perform a current meta-analysis evaluating effectiveness of antibiotic prophylaxis in preventing postoperative complications after tension-free hernioplasty.   Methods: Using search terms “hernia” and “antibiotic prophylaxis,” 2 independent investigators evaluated incision infection (primary outcome), and hematoma, respiratory or urinary tract infection (secondary outcomes), reported in all clinical trials identified in the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and the China Biological Medicine Database from inception to May 2010. Meta-analysis of these outcomes included prospective controlled RCTs with a “placebo” or “no antibiotic” control group. Study subjects were at least 18 years of age without contraindications for antibiotic use, and without immune-suppression caused by diseases or medications, who were scheduled to undergo tension-free hernioplasty. Study quality was rated on the Jadad composite scale,⁴ a 0-5 rating scale based on randomization, blinding, and subject withdrawals. Review Manager Software from the Cochrane Collaboration was used to calculate odds ratios (ORs) for each outcome using a Mantel–Haenszel fixed-effects model. The number needed to treat was calculated from the ORs and the background risk of incision infection in patients in the control group. Sensitivity analysis, adjusted by study quality and heterogeneity interactions with OR, were also evaluated. Results were considered significant at P Results: Of 124 studies evaluated, 6 RCTs on 1119 subjects treated with antibiotic and 1116 control subjects qualified for the meta-analysis. Jadad scores were 4 or 5 (high quality) for all 6 studies, of which 5 were placebo-controlled. Antibiotics used were cefazolin 1g, cefuroxime 1.5 g, ampicillin + clavulanic acid 1.2 g, or ampicillin + sulbactam 1.5 g. All studies used polypropylene mesh to reduce surgical site tension. Meta-analysis of the primary outcome found fewer SSI in tension-free hernioplasty patients treated with antibiotics (1.70%) than in placebo-treated controls (3.76%; P P Author’s Conclusions: This meta-analysis showed less than half the incidence of SSI in patients receiving antibiotic prophylaxis for tension-free hernioplasty and favored their routine use in these patients.   Clinical Perspective: These two meta-analyses confirm the value of prophylactic antibiotic use for 2 very different types of surgery: one type to deliver 1 or more babies, the other to correct a hernia, inserting a polypropylene mesh to strengthen the repairing hernia site. Baaqeel and Baaqeel² underscore the vital importance of timing of antibiotic prophylaxis. Li et al³ confirmed efficacy of antibiotics, but did not describe timing of antibiotic administration in any of the studies reviewed. Timing of prophylactic antibiotic administration clearly merits analysis in future RCTs, systematic reviews, and meta-analyses for all indications explored. If in doubt about the timing of antibiotic prophylaxis for a planned surgery, one may apply Hospital Quality Alliance measures,⁵ which have helped prevent SSI for a variety of surgeries. These measures recommend the administration of patient- and surgery-appropriate prophylactic antibiotics 1 hour before surgery, and the discontinuance of the antibiotic within 24 hours post-surgery.   Other important evidence gaps cloud prophylactic antibiotic decisions for chronic wounds. For example, the Infectious Diseases Society of America Clinical Practice Guideline for the Diagnosis and Treatment of Diabetic Foot Infections recommends 3 days to 5 days of antibiotic prophylaxis to prevent SSI if all infected tissue has been removed, or at least 4 weeks if necrotic bone is present or if infection persists for surgically managed infected diabetic foot ulcers (DFU). Timing relative to surgery is not described. This recommendation is based on only weak evidence.⁶ Considering the severity of debilitation, morbidity, and mortality associated with DFU infection,⁷ should we settle for weak evidence on antibiotic usage to prevent SSI after surgical removal of infected tissue from a DFU?   Isn’t it time to strengthen the evidence to inform clinical decisions about preventing all acute and chronic wound SSIs as well as nonsurgical infections? Let’s use science to optimize all interventions including wound dressings^8,9 and antibiotic use to minimize bacterial resistance and maximize patient-centered outcomes10 such as wound healing, pain, and infection.

References

1. Weed HG. Antimicrobial prophylaxis in the surgical patient. Med Clin North Am. 2003;87:59-75. 2. Baaqeel H, Baaqeel R. Timing of administration of prophylactic antibiotics for caesarean section: a systematic review and meta-analysis. BJOG. 2012; doi: 10.1111/1471-0528.12036. [Epub ahead of print] 3. Li JF, Lai DD, Zhang XD, et al. Meta-analysis of the effectiveness of prophylactic antibiotics in the prevention of postoperative complications after tension-free hernioplasty. Can J Surg. 2012;55(1):27-32. Doi: 10.1503/cjs.018310. 4. Jadad AR, Moore RA, Carroll D, et al. Assessing the quality of reports of randomized clinical trials: Is blinding necessary? Control Clin Trials. 1996;17:1-12. 5. Centers for Medicare & Medicaid Services. National Summary Statistics for RHQDAPU clinical process measures as reported on Hospital Compare March 2009. Baltimore, MD; 2009. https://www.cms.gov/Medicare/Quality-Initiatives-Patient-Assessment-Instruments/HospitalQualityInits/Downloads/HospitalNationalLevelPerformance.pdf Accessed March 26, 2013. 6. Lipsky BA, Berendt AR, Cornia PB, et al. 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections. Clin Infect Dis. 2012;54(12):e132-e173. 7. Snyder RJ, Hanft JR. Diabetic foot ulcers--effects on QOL, costs, and mortality and the role of standard wound care and advanced-care therapies. Ostomy Wound Manage. 2009;55(11):28–38. 8. Wiechula R. The use of moist wound-healing dressings in the management of split-thickness skin graft donor sites: a systematic review. Int J Nurs Pract. 2003;9(2):S9-S17. 9. Hutchinson JJ, McGuckin M. Occlusive dressings: A microbiologic and clinical review. Amer J Infect Control. 1990;18(4):257-268. 10. van Rijswijk L, Gray M. Evidence, research, and clinical practice: a patient-centered framework for progress in wound care. Ostomy Wound Manage. 2011; 57(9):26-38.