Infections of the Abdomen & Pelvis
In the pre-antibiotic era, mortality from penetrating colonic injury was as high as 60–75%.[63,64] However, the colon is not solely responsible for intra-abdominal postoperative infections in penetrating trauma patients. Studies have shown both gastric and pancreatic injuries increase infection rates. The highest risks for infection include peritoneal contamination with colon contents, advanced age, hemorrhagic shock/transfusion requirement and concomitant stomach injury, with both VLE and LE injuries having similar infection rates. Laparotomy is generally recommended with surgical repair for source control and concomitant antibiotics if perforated viscus is found at surgery. However, LE penetrating trauma to the liver has been managed without laparotomy with subsequent low infection rate (5%) if CT imaging was performed showing no bowel involvement. This management style requires careful serial examination to rule out missed hollow-viscus injury. Of note, whether or not perioperative antibiotics are required for liver injury without bowel involvement is unclear because this study does not mention antibiotics. The flora of the GI tract comprises aerobic and facultative Gram-positive cocci (e.g., streptococci) in the upper gut, transitioning in the distal small bowel and colon to anaerobes (e.g., B. fragilis), and aerobic and facultative Gram-negative bacilli (e.g., E. coli).P. aeruginosa IAI may emerge after prolonged antibiotic treatment. IAIs complicating penetrating trauma of the abdomen include intra-abdominal abscess, suppurative peritonitis, superficial wound infection and necrotizing fasciitis of the abdominal wall, while sepsis remains a major cause of morbidity and mortality. A recent 6-year retrospective review of LE penetrating trauma with hollow viscus injury yields interesting epidemiological results regarding the causative microbial flora of traumatic abdominal infections. Of the 14% of injuries reviewed developing an infection, 80% involved penetrating trauma, 75% had a colonic injury and 25% had a small bowel or stomach injury. E. coli predominated (55% of isolates), followed by Enterobacter cloacae (26%), Klebsiella spp. (17%) and Proteus mirabilis (4%). E. coli and Bacteroides spp. predominated in colon injury and Enterobacter and Klebsiella in stomach/small bowel injury. The second most common pathogen encountered overall was Enterococcus, and yeast was isolated in 20% of infections. Organisms remained most susceptible to cephalosporins, fluoroquinolones and carbapenems and there were no trends of increasing resistance over time, but Enterobacteriaceae were highly resistant to ampicillin/sulbactam, resulting in almost 50% of patients receiving inadequate empiric therapy.
Perioperative antibiotic therapy is the mainstay of penetrating traumatic injury to prevent subsequent IAI. A recent evidence-based study of perioperative antibiotics concluded there were no randomized placebo-controlled clinical trials to support this practice concluding, however, that all recommendations are based purely on expert opinion and arguing for a necessary clinical trial on this subject. A trial comparing preoperative, intraoperative and postoperative antibiotic therapy for penetrating abdominal injury demonstrated a 7, 33 and 30% incidence in infections, respectively. A more impressive result occurred in the subgroup analysis of colonic injuries where infections numbered 11, 57 and 70% for each group. This trial proved the superiority of preoperative antibiotics over later administration times. A subsequent study emphasized the importance of anaerobic coverage in preventing infection. Clindamycin therapy significantly reduced infection rates to 11 versus 27% for a first-generation cephalosporin. Following these two trials, investigators abandoned the practice of placebo arms in trials arguing that it was unethical. To date, no study has been able to demonstrate the advantage of continuing perioperative antibiotics for over 24 h if primary intestinal repair has occurred within 12 h of injury. A guidelines group in the year 2000 reviewed 39 publications for evidence of optimum antibiotic regimen and dosing duration. They concluded, based on two studies,[73,74] that there was adequate evidence for one preoperative dose of broad-spectrum antibiotics, with discontinuation if no hollow viscus injury is found at laparotomy, versus continuing for 24 h if an injury is identified but found no evidence for determining appropriate duration in the setting of hemorrhagic shock where antibiotic delivery is impaired. More recently, investigators found no increase in complications from stopping antibiotics under 24 h versus prolonged use in a prospective study of over 90 patients, even in severe injury when the abdomen is left open. Furthermore, over 24 h of antibiotics leads to increased bacteria with antibiotic resistance and death from these drug-resistant pathogens. Recent guidelines recommend cefoxitin 2 g every 6 h or moxifloxacin 400 mg daily monotherapy, or alternatively levofloxacin 750 mg or ciprofloxacin 400 mg combined with metronidazole 500 mg every 8 h as primary perioperative prophylaxis. Additional regimens also thought to be effective if your local antibiogram has high rates of resistance to primary agents include single-agent ticarcillin/clavulanate, ertapenem, moxifloxacin or tigecycline, or combinations of metronidazole with either cefazolin, cefuroxime, ceftriaxone or cefotaxime, again limiting to 24 h postoperatively. In summary, based on all available literature (Table 5), we recommend cefoxitin or moxifloxacin monotherapy, or alternatively ciprofloxacin combined with metronidazole, as perioperative agents of choice with an AI level of evidence. Antibiotics should be started prior to surgery, and based on several prospective randomized trials (AI level of evidence) continued for no more than 24 h.
Antibiotic Therapy for Infection
The optimum antibiotic therapy for IAI following trauma remains unclear. However, incorrect empiric therapy results in higher mortality. Recent guidelines have been published advocating empiric single-agent ticarcillin/clavulanate, cefoxitin, ertapenem, moxifloxacin or tigecycline, plus combinations of metronidazole with either cefazolin, cefuroxime, ceftriaxone, cefotaxime, levofloxacin or ciprofloxacin as first-line therapy for IAI, and limiting treatment to 4–7 days. Guidelines specifically recommend against the use of empiric ampicillin/sulbactam, clindamycin, cefotetan, fluoroquinolone-based regimens when hospital antibiograms indicate less than 90% E. coli susceptibility, and against empiric coverage for enterococcus or yeast in moderate IAI. The guidelines do not mention penetrating trauma except for perioperative prophylaxis, and penetrating trauma is often excluded entirely from the studies that form the basis for this guidance. For HE injury, a recent guideline suggested infections developing after 48 h, or with accompanying sepsis, are highly likely to be nosocomial based on previous studies and recommended therapy based on hospital antibiogram. They suggested a number of regimens suitable for nosocomial infection including piperacillin/tazobactam, carbapenems, advanced-generation cephalosporin (ceftazidime or cefepime) with metronidazole, or aztreonam with metronidazole. For infections less then 48 h old or with no sepsis they recommended fluoroquinolone (ciprofloxacin or levofloxacin) with metronidazole, third-generation cephalosporin (cefotaxime or ceftriaxone) with metronidazole, ticarcillin/clavulanic acid or moxifloxacin monotherapy. Tigecycline might also be a useful agent in this setting, and has activity against Acinetobacter spp. as well, although it has been recently associated with an increase in mortality in certain populations. In summary (see Table 5), based on our opinion and two recent consensus statements (BIII level of evidence)[50,77] we recommend ticarcillin/clavulanate, cefoxitin, ertapenem or moxifloxacin if injury is under 48 h old or mild/moderate and a carbapenem or piperacillin/tazobactam if over 48 h old or severe.
Expert Rev Anti Infect Ther. 2011;9(1):81-96. © 2011 Expert Reviews Ltd.
Cite this: Prophylaxis and Treatment of Infections Associated with Penetrating Traumatic Injury - Medscape - Jan 01, 2011.