In a call to arms entitled, 'Antimicrobial Stewardship; a call to action for surgeons.' A panel of experts from the surgical infection Society and the World Society of emergency surgery, strongly warned surgeons of the imperative need for the judicious use of antibiotics. There admonishment states, that if surgeons fail to actively engage and use antibiotics judiciously, they will find themselves deprived the autonomy to treat their patients. In important example of the consequences of continued antimicrobial misuse and increasing antimicrobial resistance is that of surgical site infections. In the face of increasing antimicrobial resistance, routine antibiotic prophylaxis will progressively lose efficacy and preventive surgical site infections, and may render some elective surgical procedures like joint replacements too risky to perform. One model found that a 30 percent reduction in the efficacy of antibiotic prophylaxis for the 10 most common surgical procedures performed in the US would result in approximately 120,000 additional surgical side infections per year. Surgical prophylaxis is an obvious target for engaging surgeons and stewardship efforts, and we discussed current best practices for prophylaxis in a separate module. Another potential target is intra-abdominal infections. First, some definitions. Intra-abdominal infections are due to inflammation or disruption of the gastrointestinal track or less commonly, the genitourinary tract. The most common intra-abdominal infections in adults include cholecystitis, appendecitis and diverticulitis. Intra-abdominal infections can be classified as complicated or uncomplicated based on the extent of infection. Uncomplicated infections are limited to intramural inflammation of the gastrointestinal track, while complicated infections involve anatomic disruption such as bowel perforation allowing for the infection to extend beyond the hollow viscous of origin into the intra-peritoneal space, resulting in an associated abscess or pair tinnitus. Intra-abdominal infections are often polymicrobial, cultures when they are obtained are generally representative of normal flora from the inflamed viscous. In many of these infections especially those that are complicated by bowel perforation, antimicrobial serve only as an adjunct to critical source control which is necessary for the eradication of infection. Stewardship programs can play an important role in the management of intra-abdominal infections. First, ASPs can develop recommendations for the choice of empiric antimicrobial therapy for these infections, and can distribute these recommendations via clinical pathways or guidelines, and thus limiting the empiric use of anti-pseudomonal agents. ASPs can also help clinicians respond appropriately to intra-operative cultures when available. ASPs can advise de-escalation from broad-spectrum empiric antimicrobial therapy when appropriate. In addition, ASPs can counsel clinicians against broadening antimicrobial coverage because of culture results for patients who are improving on an empiric regimen. Many times, intra-operative cultures are polymicrobial and sometimes unsuspected organisms are recovered. The SIS-IDSA guidelines recommend that for lower risk patients with community acquired intra-bdominal infections, alteration of therapy is not necessary if the patient's clinical response to source control and initial therapy is satisfactory, even if unsuspected and untreated pathogens are later reported. Emerging literature also suggest two other potential targets for ASPs, the total duration of therapy for intra-abdominal infections and empiric therapy for diverticulitis. First, the duration of therapy. The 2010 SIS-IDSA guidelines for the management of complicated intra-abdominal infections, recommended that antimicrobial therapy be limited to 4-7 days unless adequate source control was not possible. A recent study known as the STOP-IT trial, further supports that recommendation. Providing evidence that four days of therapy is sufficient even if elements of a systemic inflammatory response are still present. In this multi-center study, 518 adult patients with complicated intra-abdominal infections and adequate source control were randomized to either the control arm, who received antibiotics for two days after the resolution of fever, leukocytosis and ileus with a maximum of a 10-day course of therapy or to the experimental arm, who received a fixed cost of four plus or minus one days of antibiotics. One-third of these infections originated in the colon or rectum, another 14 percent in the small bowel, and 14 percent in the appendix. Source control was achieved by means of percutaneous drainage and 33 percent of the patients, surgical resection in 26 percent of the patients and surgical drainage alone in 21 percent. The median duration of antibiotics was four days in the experimental arm versus eight days in the control arm. The primary outcome was a composite of surgical site infection, recurrent intra-abdominal infection, or death within 30- days of the source control procedure. The authors reported similar rates of complications in both groups. Approximately 20 percent of patients in each group developed complications after treatment. Although the rates were similar, the time to diagnosis of a surgical site infection or recurrent intra-abdominal infection was shorter in the experimental arm, or short-course therapy arm. It has been postulated that prolonged antimicrobial suppress the inflammatory response in the long course arm, leading to delayed recognition of relapse, which could lead to increased cost of care including possible increase length of hospital stay, and complications as a result of repeat antibiotic exposure. Two post-hoc analyses compared outcomes of high risk patients treated with short-course versus long-course therapy. In one, the authors found similar complication rates in patients who presented with sepsis. In a second, the authors reported similar complication rates in patients with diabetes, obesity or increased severity of illness. This study supports limiting the duration of therapy after source control for patients with complicated intra-abdominal infections and can be incorporated into local guidelines or pathways, as well as ASPs routine audit and feedback. Another potential target is the management of uncomplicated diverticulitis. Diverticulitis is the inflammation of a diverticulum or sac like protrusion of the colonic wall. Until recently, broad-spectrum empiric antimicrobial use was universally recommended for the management of all cases of diverticulitis. However, the 2015 American gastro-enterological associations guidelines, on the management of acute diverticulitis, suggested that clinicians individualize their approach to patients with mild disease. The AGA suggested that antibiotics should be used selectively, rather than routinely in patients with acute and complicated diverticulitis. They did caution that this recommendation was founded on a weak evidence base of two systematic reviews and two clinical trials. More data has emerged since those guidelines were released, for example, one perspective cohort trial conducted in Finland, evaluated the impact of symptomatic therapy without antibiotics for patients with uncomplicated acute diverticulitis. When 161 patients with uncomplicated acute diverticulitis, verified on CT scan were included in the study, and the majority were managed as outpatients. Immuno-suppressed patients including those with diabetes mellitus, were excluded from this study. Patients were reevaluated 24 to 48 hours after enrollment at which point clinicians were allowed to start antibiotics if they were not improving. Only 14 patients were started the antibiotics in this cohort, and no patients develop complications in the 30-day follow-up period. Another study was a multicenter trial, conducted in the Netherlands that randomized 528 patients with CT proven primary, left sided, uncomplicated acute diverticulitis to observation, or 10 days of broad-spectrum antimicrobial therapy. Patients randomized to receive antibiotics were initially hospitalized for intravenous therapy. Patients randomized to the observational arm, were managed as an outpatient when they became a febrile and were tolerated in an oral diet. The authors found no significant difference in the median time to recovery, the primary outcome of the study or in complication rates between the two groups. Patients in the observational group had a significantly shorter length of hospital stay of two versus three days. Thus, these two studies add to the growing body of evidence suggesting that antibiotic therapy for CT confirmed, uncomplicated diverticulitis does not produce better outcomes than conservative medical management alone. Although the management of intra-abdominal infections can be challenging, emerging data suggests that ASPs could play an important role in working with surgeons and other stakeholders to optimize antimicrobial use for these infections. One way is to use the guideline recommendations in clinical evidence reviewed in this module to inform institutional guidelines. Program should stay an alert for more developments that are sure to come in the field of intra-abdominal infections.
