Abdominal surgical wound infection is lowered with improved perioperative enterococcus and bacteroides therapy

Prophylactic antibiotic use in penetrating abdominal trauma: an Eastern Association for the Surgery of Trauma practice management guideline

BACKGROUND

The use of prophylactic antibiotics in penetrating abdominal trauma has resulted in decreased infection rates. The Eastern Association for the Surgery of Trauma (EAST) first published its practice management guidelines (PMGs) for the use of prophylactic antibiotics in penetrating abdominal trauma in 1998. During the next decade, several new prospective studies were published on this topic. In addition, the practice of damage control laparotomy became widely used, and additional questions arose as to the role of prophylactic antibiotics in this setting. Thus, the EAST Practice Management Guidelines Committee set out to update the original PMG.

METHODS

A search of the National Library of Medicine and the National Institutes of Health MEDLINE databases was performed using PubMed (www.pubmed.gov) and specific key words. The search retrieved English language articles regarding the use of antibiotics in penetrating abdominal trauma published from 1973 to 2011. The topics investigated were the need for perioperative antibiotics, the duration of antibiotic therapy, the dose of antibiotics in patients presenting in hemorrhagic shock, and the appropriate duration of antibiotic therapy in the setting of damage control laparotomy.

RESULTS

Forty-four articles were identified for inclusion in this review.

CONCLUSION

There is evidence to support a Level I recommendation that prophylactic antibiotics should only be administered for 24 hours in the presence of a hollow viscus injury. In addition, there are no data to support continuing prophylactic antibiotics longer than 24 hours in damage control laparotomy.

Microbiological profile and antimicrobial susceptibility in surgical site infections following hollow viscus injury

INTRODUCTION

The purpose of this study was to assess the microbiological profile, antimicrobial susceptibility, and adequacy of the empiric antibiotic therapy in surgical site infections (SSI) following traumatic hollow viscus injury (HVI).

METHODS

This is a retrospective study of patients admitted with an HVI from March 2003 to July 2009. SSI was defined as a wound infection or intra-abdominal collection confirmed by positive cultures and requiring percutaneous or surgical drainage.

RESULTS

A total of 91 of 667 (13.6%) patients with an HVI developed an SSI confirmed by positive culture. Mean age was 33.0 +/- 14.1 years, mean Injury Severity Score (ISS) was 17.7 +/- 9.6, 91.2% were male, and 80.2% had sustained penetrating injuries. The SSI consisted of 65 intra-abdominal collections and 26 wound infections requiring intervention. The most commonly isolated species in the presence of a colonic injury was Escherichia coli (64.7%), Enterococcus spp. (41.2%), and Bacteroides (29.4%), and in the absence of a colonic perforation, Enterococcus spp. and Enterobacter cloacae (both 38.9%). Susceptibility rates of E. coli and E. cloacae, respectively, were 38% and 8% for ampicillin/sulbactam, 82% and 4% for cefazolin, 96% and 92% for cefoxitin, with both 92% to piperacillin/tazobactam, and 100% to ertapenem. The initial empirical antibiotic therapy adequately targeted the pathogens in 51.6% of patients who developed an SSI.

CONCLUSION

The distribution of the microorganisms isolated from SSIs differed significantly according to whether or not a colonic injury was present. Empiric antibiotic treatment was inadequate in upwards of 50% of patients who developed an SSI. Further investigation is warranted to determine the optimal empiric antibiotic regimen for reducing the rate of postoperative SSI.

Multicenter study evaluating the role of enterococci in secondary bacterial peritonitis

A 1-year prospective multicenter study was performed to explore the significance of the presence of enterococci in cultures of peritoneal fluid from patients with secondary bacterial peritonitis in seven Spanish hospitals. The clinical records of patients with positive peritoneal fluid cultures were reviewed and distributed into cases (patients with cultures yielding enterococci) and controls (patients with cultures not yielding enterococci). Of a total of 158 records, 38 (24.1%) were cases and 120 (75.9%) were controls. The percentages or the scores (cases versus controls) for the variables included in the multivariate analysis were as follows: age of >50 years, 89.5% versus 68.3%; malignancy, 39.5% versus 18.3%; chronic obstructive pulmonary disease (COPD), 15.8% versus 4.2%; postoperative peritonitis, 55.3% versus 30.1%; nosocomial onset, 57.9% versus 34.2%; a higher Charlson comorbidity index, 3.29 +/- 3.38 versus 1.84 +/- 2.31; APACHE II score, 10.71 +/- 4.37 versus 8.76 +/- 5.49; ultimately or rapidly fatal disease, 63.2% versus 34.8%; need for surgical reintervention, 36.1% versus 15.1%; and admission to an intensive care unit, 45.9% versus 30.8%. In the multivariate analysis, enterococci were associated only with postoperative peritonitis (P = 0.009; odds ratio [OR] = 5.0; 95% confidence interval [CI] = 1.49 to 16.80), a higher Charlson comorbidity index (P = 0.002; OR = 1.30; 95% CI = 1.11 to 1.54), and COPD (P = 0.046; OR = 6.50; 95% CI = 1.04 to 40.73). The results of this study showed that enterococci were associated with comorbidity. An association with mortality could not be demonstrated.

Clinical and microbiological profiles of community-acquired and nosocomial intra-abdominal infections: results of the French prospective, observational EBIIA study

OBJECTIVES

The EBIIA (Etude épidémiologique Bactério-clinique des Infections Intra-Abdominales) study was designed to describe the clinical, microbiological and resistance profiles of community-acquired and nosocomial intra-abdominal infections (IAIs).

PATIENTS AND METHODS

From January to July 2005, patients undergoing surgery/interventional drainage for IAIs with a positive microbiological culture were included by 25 French centres. The primary endpoint was the epidemiology of the microorganisms and their resistance to antibiotics. Multivariate analysis was carried out using stepwise logistic regression to assess the factors predictive of death during hospitalization.

RESULTS

Three hundred and thirty-one patients (234 community-acquired and 97 nosocomial) were included. The distribution of the microorganisms differed according to the type of infection. Carbapenems and amikacin were the most active agents in vitro against Enterobacteriaceae in both community-acquired and nosocomial infections. Against Pseudomonas aeruginosa, amikacin, imipenem, ceftazidime and ciprofloxacin were the most active agents in community-acquired infections, while imipenem, cefepime and amikacin were the most active in nosocomial cases. Against the Gram-positive bacteria, vancomycin and teicoplanin were the most active in both infections. Against anaerobic bacteria, the most active agents were metronidazole and carbapenems in both groups. Empirical antibiotic therapy adequately targeted the pathogens for 63% of community-acquired and 64% of nosocomial peritonitis. The presence of one or more co-morbidities [odds ratio (OR) = 3.17; P = 0.007], one or more severity criteria (OR = 4.90; P < 0.001) and generalized peritonitis (OR = 3.17; P = 0.006) were predictive of death.

CONCLUSIONS

The principal results of EBIIA are a higher diversity of microorganisms isolated in nosocomial infections and decreased susceptibility among these strains. Despite this, the adequacy of treatment is comparable in the two groups.

Antibiotics and gastrointestinal colonization by vancomycin-resistant enterococci

Although several classes of antimicrobial agents have been associated with colonization or infection with glycopeptide-resistant enterococci (GRE) in individual clinical studies, the agents most commonly implicated are extended-spectrum cephalosporins and compounds with potent activity against anaerobic bacteria, including ticarcillin-clavulanic acid. In some clinical studies, formulary alterations designed to minimize the use of extended-spectrum cephalosporins or ticarcillin-clavulanic acid have resulted in significant decreases in colonization and infection by GRE. Experimental data using a mouse model of GRE gastrointestinal colonization indicate that persistence of high-level GRE colonization of the mouse gastrointestinal tract is promoted by exposure to agents with potent activity against anaerobic bacteria, suggesting that reduction of competing flora is the major factor leading to persistence of high-level colonization. One study performed in humans is consistent with this model and suggests that high levels of colonization may promote spread of resistant organisms in the nosocomial setting. Establishing colonization with GRE in uncolonized mice correlates with exposure to agents that are (a) secreted into the bile in significant concentrations and (b) have negligible activity against the colonizing enterococcal strain. Differences between piperacillin-tazobactam and ceftriaxone in the establishment model can be attributed directly to differences in their anti-enterococcal activity. Modification of antimicrobial prescribing practices may play an important role in facilitating successful infection control efforts to limit GRE in the nosocomial setting.

Emerging bacterial pathogens: a consensus of the scientific data and the risk for development of multiple organ dysfunction syndrome

Antibiotic resistance in the hospital setting is continuing to increase, particularly in intensive care units (ICUs) and other areas of the hospital such as oncology units, where the use of empiric broad-spectrum antibiotics is common. The problem of antibiotic resistance is also compounded in the immunocompromised patient. Multi-drug resistance is common among both Gram-positive and -negative bacteria, and becoming more prevalent among fungi (yeast). Two major antibiotic-resistant pathogens include extended-spectrum beta-lactamase producing Klebsiella pneumoniae (ESBL-KP) and vancomycin-resistant enterococci (VRE). When infections occur with ESBL-KP, a carbapenem antibiotic is usually the drug of choice. When infection occurs with VRE, specific therapy is bacteriostatic, and the clinician may have to rely on empirically selected antibiotics or combinations of antibiotics to achieve a positive outcome. Two newly-approved agents, linezolid and quinupristin/dalfopristin can be used to treat infections caused by resistant gram-positive cocci, but the latter is approved for use against VR-E. faecium. Risk factors for the development of ESBL-KP include the use of extended-spectrum cephalosporins such as ceftazidime. Risk factors for the development of VRE include inappropriate use of vancomycin, extended-spectrum cephalosporins, and antianaerobic drug therapy such as clindamycin. Several institutions have documented a reduction in one or both of these resistant pathogens following a decrease in the use of extended-spectrum cephalosporins combined with the increased use of extended-spectrum penicillins/beta-lactamase inhibitor combinations, such as piperacillin/tazobactam, for the empiric therapy of infections. For VRE, a reduction in the inappropriate use of vancomycin is also an important interventional strategy along with improved infection control practice.

Basic aspects of and general problems in surgical infections

Antibiotics are important in the prophylaxis and treatment of surgical infections as well as in the management of nosocomial infections acquired postoperatively in surgical patients. Surgeons encounter a range of infectious conditions, including established single-pathogen infections of soft tissues, polymicrobial intra-abdominal infections, and resistant gram-negative nosocomial infections such as ventilator-associated and aspiration pneumonia. Preoperative antibiotic administration has been shown to reduce the risk of surgical site infections and is now an accepted part of the standard care for most surgical patients. In patients with established single-pathogen or polymicrobial infections requiring surgery, studies have shown appropriate empiric antibiotic therapy to be an important adjunct to surgical intervention and general supportive measures in improving patient outcome. Antibiotics are also essential for those who develop postoperative nosocomial infections. Empiric coverage of the most likely causative organisms, especially in synergistic polymicrobial mixed infections, is one of the keys to successful prophylaxis and treatment of surgical infections.

The role of beta-lactam/beta-lactamase inhibitor combinations in surgical infections

Many surgical infections are characterized by synergistic polymicrobial mixed infection, for which broad-spectrum antimicrobial therapy is usually administered on an empiric basis. Until relatively recently, standard empiric therapeutic regimens have involved the use of two or more antibiotics, such as aminoglycosides and anti-anaerobic agents, to achieve adequate aerobic and anaerobic coverage. There are often substantial drawbacks, however, such as drug-induced toxicity and high costs of treatment. Evidence from a number of clinical studies suggests that single-agent therapy with beta-lactam/beta-lactamase inhibitor combinations is a suitable and cost-effective alternative to multidrug regimens, as well as to monotherapy with cephalosporins or carbapenems in the treatment of intra-abdominal, gynecologic, and diabetic foot infections, and brain abscesses. These agents are also suitable for use in perioperative prophylaxis and may offer benefits over other agents in terms of reduced incidence of surgical wound infections and lower costs.

Analysis of 162 Colon Injuries in Patients with Penetrating Abdominal Trauma: Concomitant Stomach Injury Results in a Higher Rate of Infection

BACKGROUND

Fecal contamination from colon injury has been thought to be the most significant factor for the development of surgical site infection (SSI) after trauma. However, there are increasing data to suggest that other factors may play a role in the development of postinjury infection in patients after colon injury. The purpose of this study was to determine the impact of gastric wounding on the development of SSI and nonsurgical site infection (NSSI) in patients with colon injury.

METHODS

Post hoc analysis was performed on data prospectively collected for 317 patients presenting with penetrating hollow viscus injury. One hundred sixty-two patients with colon injury were subdivided into one of three groups: patients with isolated colon wounds (C), patients with colon and stomach wounds with or without other organ injury (C+S), and patients with colon and other organ injury but no stomach injury (C-S) and assessed for the development of SSI and NSSI. Infection rates were also determined for patients who sustained isolated gastric injury (S) and gastric injury in combination with other injuries other than colon (S-C). Penetrating Abdominal Trauma Index, operative times, and transfusion were assessed. Discrete variables were analyzed by Cochran-Mantel-Haenszel chi2 test and Fisher's exact test. Risk factor analysis was performed by multivariate logistic regression.

RESULTS

C+S patients had a higher rate of SSI infection (31%) than C patients (3.6%) (p=0.008) and C-S patients (13%) (p=0.021). Similarly, the incidence of NSSI was also significantly greater in the C+S group (37%) compared with the C patients (7.5%) (p=0.07) and the C-S patients (17%) (p=0.019). There was no difference in the rate of SSI or NSSI between the C and C-S groups (p=0.3 and p=0.24, respectively). The rate of SSI was significantly greater in the C+S patients when compared with the S-C patients (31% vs. 10%, p=0.008), but there was no statistical difference in the rate of NSSI in the C+S group and the S-C group (37% vs. 24%, p=0.15).

CONCLUSION

The addition of a gastric injury to a colon injury has a synergistic effect on the rate of postoperative infection.

[Enterococcal infections in critically ill patients admitted to ICU]

BACKGROUND AND OBJECTIVE

To determine the frequency of infections caused by Enterococcus spp. in critically ill patients admitted to ICUs in Spain and to describe the clinical features and outcome of those patients in whom this pathogen was isolated.

PATIENTS AND METHOD

Prospective, observational, multicenter study. Patients admitted to the ICUs who participated in the National Surveillance Study of Nosocomial Infections (ENVIN) from 1997 to 2001 were included. Patients were classified as infected by Enterococcus spp., infected by other pathogens, and without nosocomial infection (non-infected).

RESULTS

Of 21,972 patients, 2,177 (9.9%) had acquired 3,490 nosocomial infections during their stay in the ICU. In 223 patients (10.2%), 239 episodes of infections in which one of the causative pathogen was Enterococcus spp. were identified (cumulative incidence 1.1 episodes of Enterococcus spp. infection per 100 patients). Enterococcus spp. accounted for urinary infection in 14.3% of cases and secondary bacteremia in 12.2% especially those related with abdominal infection (20%) and soft tissue infection (21.4%). Predominant species was E. faecalis in 197 isolates (82.4%). After multivariate analysis, variables significantly associated with infection caused by Enterococcus spp. included: age (odds ratio [OR]=1.13; 95% confidence interval [CI], 1.01-1.25); APACHE II score (OR=1.19; CI 95%, 1.07-1.32); and length of ICU stay (OR=1.02; CI 95%, 1.01-1.03). There were no differences in the overall ICU mortality rate between patients with Enterococcus spp. infection (31.8%) and those with infection caused by other pathogens (31.8%), although in both cases the mortality rate was significantly higher than in non-infected patients (11.1%).

CONCLUSIONS

Enterococcus spp. was present in 10.2% patients with ICU-acquired infection. Infection by Enterococcus spp. mainly occurred in the form of urinary tract infection and secondary bacteremia, mainly related to abdominal and soft tissue infections. E. faecalis predominated in all foci. There were no differences in mortality between patients with Enterococcus spp. infection and patients with infection caused by other pathogens.

Coverage of enterococci in community acquired secondary peritonitis: results of a randomized trial

INTRODUCTION

The increasing number of enterococcal infections in hospitals and reports about the development of resistance of these bacteria make it necessary to review their importance as co-pathogens in secondary peritonitis.

MATERIALS AND METHODS

A prospective randomized controlled trial on primary therapy of secondary peritonitis was carried out in six centers comparing cephalosporin-based antibiotic therapy to acylaminopenicillin-based therapy.

RESULTS

Enterococci were only cultured in 6 of 110 cases from the abdomen and were found in only 5 cases of postoperative complications. No differences were found between penicillin-based vs. cephalosporin-based therapy.

CONCLUSION

The study supports the view that these bacteria continue to play a minor role in secondary peritonitis. The point has to be emphasized, however, that the patients under study were in relatively good condition (APACHE II median 9 for cephalosporins and 10 for penicillins) and that postoperative cases of peritonitis were excluded.

The role of beta-lactam antimicrobials as single agents in treatment of intra-abdominal infection

Broad-spectrum beta-lactam antibiotics have several advantages in the treatment of intra-abdominal infections. These agents are effective against gram-negative rods and anaerobes, reach therapeutic levels rapidly after parenteral administration, and, in the absence of penicillin allergy, generally exhibit low toxicity. The second-generation cephalosporins (e.g., cefoxitin, cefotetan) are used widely in surgical prophylaxis, trauma, and treatment of mild-to-moderate community-acquired infections, but limitations in their spectra and microbial resistance restrict their utility in more serious infections. Extended-spectrum penicillin/beta-lactamase-inhibitor combinations are effective in the treatment of intra-abdominal infections and include enterococci in their spectrum. Gram-negative aerobe resistance has developed to ampicillin/sulbactam. Piperacillin/tazobactam, a ureidopenicillin with increased gram-negative coverage and enhanced antipseudomonal activity, has proved to be effective in clinical trial therapy for intra-abdominal infections. The very broad spectrum carbapenems--imipenem/cilastatin and meropenem--are effective for serious infections or resistant organisms and are often used in the intensive care unit or for nosocomial intra-abdominal infection. These classes of beta-lactams comprise a range of antimicrobials that can be targeted effectively as single agents to both prevention and treatment of intra-abdominal infection.

Anaerobic infections in the surgical patient: microbial etiology and therapy

Anaerobic infections occur in surgical patients in part because of structural or functional defects in the host that (1) cause a breech in the normal mucosal barriers, (2) create localized vascular insufficiencies, or (3) produce an obstruction. Any or all of these events may compromise the oxidation-reduction potential within the tissues, encouraging rapid anaerobic growth. Although diverse anaerobic populations are spread throughout the gastrointestinal tract, a relatively limited number of organisms are responsible for clinical infection in the surgical patient. Many of these offending organisms express overt virulence factors that enhance microbial adherence, tissue destruction, and, in the case of Bacteroides fragilis, facilitate abscess formation. The selection of an appropriate perioperative or therapeutic agent requires a fundamental knowledge of the microbial ecology of this microbial population. The failure to consider the anaerobic flora as a component in the etiology of mixed surgical infections is associated with a high rate of perioperative and therapeutic failures.

Postoperative enterococcal infection after treatment of complicated intra-abdominal sepsis

BACKGROUND

The prevalence of enterococcal isolation and factors associated with postoperative enterococcal infection remain ill defined.

METHODS

A prospective longitudinal observational study was conducted of consecutive patients with a first episode of intra-abdominal infection and a positive microbiological culture who did or did not develop a postoperative septic complication involving enterococci. The prevalence of initial enterococcal isolation was determined for each focus of infection. Postoperative enterococcal infections were related to whether appropriate (piperacillin--tazobactam), suboptimal (carbapenems) or inappropriate (cefotaxime plus metronidazole) antienterococcal therapy had been administered empirically.

RESULTS

Enterococci were isolated in 42 (21 per cent) of the 200 patients investigated. The isolation rates were 11 per cent for community-acquired peritonitis, 50 per cent for postoperative peritonitis and 23 per cent for intra-abdominal abscesses of both origins. No enterococci were isolated from 49 patients with perforated appendicitis. Independent factors for postoperative enterococcal infection were type of intra-abdominal infection (P = 0.006), Acute Physiology And Chronic Health Evaluation (APACHE) II score greater than 12 (P = 0.04) and inappropriate empirical antibiotic cover (P = 0.05). Postoperative enterococcal infections were associated with a high mortality rate (21 versus 4 per cent; P < 0.0007).

CONCLUSION

Enterococci are frequently isolated from intra-abdominal infections of non-appendiceal origin and are often involved in postoperative infectious complications, particularly peritonitis. Empirical antibiotic therapy covering Enterococcus faecalis should be contemplated in some circumstances.

Handsewn versus stapled anastomosis in penetrating colon injuries requiring resection: a multicenter study

BACKGROUND

Although the use of stapling devices in elective colon surgery has been shown to be as safe as handsewn techniques, there have been concerns about their safety in emergency trauma surgery. The purpose of this study was to compare stapled with handsewn colonic anastomosis following penetrating trauma.

METHODS

This was a prospective multicenter study and included patients who underwent colon resection and anastomosis following penetrating trauma. Multivariate logistic regression analysis was used to identify independent risk factors for abdominal complications and compare outcomes between stapled and handsewn repairs.

RESULTS

Two hundred seven patients underwent colon resection and primary anastomosis. In 128 patients (61.8%) the anastomosis was performed with handsewing and in the remaining 79 (38.2%) with stapling devices. There were no colon-related deaths and the overall incidence of colon-related abdominal complications was 22.7% (26.6% in the stapled group and 20.3% in the handsewn group, p = 0.30). The incidence of anastomotic leak was 6.3% in the stapled group and 7.8% in the handsewn group (p = 0.69). Multivariate analysis adjusting for blood transfusions, fecal contamination, and type of antibiotic prophylaxis showed that the adjusted odds ratio (OR) of complications in the stapled group was 0.83 (95% CI, 0.38-1.74, p = 0.63). In a second multivariate analysis adjusting for blood transfusions, hypotension, fecal contamination, Penetrating Abdominal Trauma Index, and preoperative delays the adjusted OR in the stapled group was 0.99 (95% CI, 0.46-2.11, p = 0.99).

CONCLUSION

The results of this study suggest that the method of anastomosis following colon resection for penetrating trauma does not affect the incidence of abdominal complications and the choice should be surgeon's preference.

Penetrating colon injuries requiring resection: diversion or primary anastomosis? An AAST prospective multicenter study

BACKGROUND

The management of colon injuries that require resection is an unresolved issue because the existing practices are derived mainly from class III evidence. Because of the inability of any single trauma center to accumulate enough cases for meaningful statistical analysis, a multicenter prospective study was performed to compare primary anastomosis with diversion and identify the risk factors for colon-related abdominal complications.

METHODS

This was a prospective study from 19 trauma centers and included patients with colon resection because of penetrating trauma, who survived at least 72 hours. Multivariate logistic regression analysis was used to compare outcomes in patients with primary anastomosis or diversion and identify independent risk factors for the development of abdominal complications.

RESULTS

Two hundred ninety-seven patients fulfilled the criteria for inclusion and analysis. Overall, 197 patients (66.3%) were managed by primary anastomosis and 100 (33.7%) by diversion. The overall colon-related mortality was 1.3% (four deaths in the diversion group, no deaths in the primary anastomosis group, p = 0.012). Colon-related abdominal complications occurred in 24% of all patients (primary repair, 22%; diversion, 27%; p = 0.373). Multivariate analysis including all potential risk factors with p values < 0.2 identified three independent risk factors for abdominal complications: severe fecal contamination, transfusion of > or = 4 units of blood within the first 24 hours, and single-agent antibiotic prophylaxis. The type of colon management was not found to be a risk factor. Comparison of primary anastomosis with diversion using multivariate analysis adjusting for the above three identified risk factors or the risk factors previously described in the literature (shock at admission, delay > 6 hours to operating room, penetrating abdominal trauma index > 25, severe fecal contamination, and transfusion of > 6 units blood) showed no statistically significant difference in outcome. Similarly, multivariate analysis and comparison of the two methods of colon management in high-risk patients showed no difference in outcome.

CONCLUSION

The surgical method of colon management after resection for penetrating trauma does not affect the incidence of abdominal complications, irrespective of associated risk factors. Severe fecal contamination, transfusion of > or = 4 units of blood within the first 24 hours, and single-agent antibiotic prophylaxis are independent risk factors for abdominal complications. In view of these findings, the reduced quality of life, and the need for a subsequent operation in colostomy patients, primary anastomosis should be considered in all such patients.

Effect of antibiotic therapy on the density of vancomycin-resistant enterococci in the stool of colonized patients

BACKGROUND

Colonization and infection with vancomycin-resistant enterococci have been associated with exposure to antibiotics that are active against anaerobes. In mice that have intestinal colonization with vancomycin-resistant enterococci, these agents promote high-density colonization, whereas antibiotics with minimal antianaerobic activity do not.

METHODS

We conducted a seven-month prospective study of 51 patients who were colonized with vancomycin-resistant enterococci, as evidenced by the presence of the bacteria in stool. We examined the density of vancomycin-resistant enterococci in stool during and after therapy with antibiotic regimens and compared the effect on this density of antianaerobic agents and agents with minimal antianaerobic activity. In a subgroup of 10 patients, cultures of environmental specimens (e.g., from bedding and clothing) were obtained.

RESULTS

During treatment with 40 of 42 antianaerobic-antibiotic regimens (95 percent), high-density colonization with vancomycin-resistant enterococci was maintained (mean [+/-SD] number of organisms, 7.8+/-1.5 log per gram of stool). The density of colonization decreased after these regimens were discontinued. Among patients who had not received antianaerobic antibiotics for at least one week, 10 of 13 patients who began such regimens had an increase in the number of organisms of more than 1.0 log per gram (mean increase, 2.2 log per gram), whereas among 10 patients who began regimens of antibiotics with minimal antianaerobic activity, there was a mean decrease in the number of enterococci of 0.6 log per gram (P=0.006 for the difference between groups). When the density of vancomycin-resistant enterococci in stool was at least 4 log per gram, 10 of 12 sets of cultures of environmental specimens had at least one positive sample, as compared with 1 of 9 sets from patients with a mean number of organisms in stool of less than 4 log per gram (P=0.002).

CONCLUSIONS

For patients with vancomycin-resistant enterococci in stool, treatment with antianaerobic antibiotics promotes high-density colonization. Limiting the use of such agents in these patients may help decrease the spread of vancomycin-resistant enterococci.

Perioperative antibiotic use in high-risk penetrating hollow viscus injury: a prospective randomized, double-blind, placebo-control trial of 24 hours versus 5 days

BACKGROUND

The purpose of this study was to compare the safety and therapeutic efficacy of a 24-hour versus 5-day course of ampicillin/sulbactam for the prevention of postoperative infections in high-risk patients sustaining hollow viscus injury from penetrating abdominal trauma.

METHODS

A total of 317 patients from four Level I trauma centers with penetrating abdominal injuries and at least one hollow viscus perforation each received one preoperative and three postoperative doses of ampicillin/sulbactam 3 g intravenously. After receiving 24 hours of unblinded ampicillin/sulbactam, patients were then randomized into one of two groups. Group 1 received 4 additional days of blinded ampicillin/sulbactam (5 days total of antibiotic), and Group 2 received 4 days of placebo (24 hours of antibiotic). Patients were assessed postoperatively for occurrence of deep surgical-site infections (intra-abdominal abscess, fasciitis, and peritonitis) and superficial (wound) surgical-site infections. Development of nonsurgical-site infections (e.g., pneumonia, urinary tract infection, phlebitis, and cellulitis) was also recorded. Continuous variables were analyzed by analysis of variance and discrete variables by the Cochran-Mantel-Haenszel chi2 test. Multivariate logistic regression analyses were also performed to identify independent risk factors for postoperative infection.

RESULTS

A total of 159 patients were randomized into Group 1, and 158 patients were randomized into Group 2. The Injury Severity Score and penetrating abdominal trauma index were 18+/-8 and 21+/-13, respectively, for Group 1 and 18+/-9 and 20+/-15, respectively, for Group 2. A total of 162 (51%) patients sustained one or more colon injuries (82 in Group 1 and 80 in Group 2). There were 16 (10%) surgical-site infections in Group 1 and 13 (8%) surgical-site infections in Group 2 (p = 0.74). Group 1 patients experienced 17 (11%) nonsurgical-site infections, whereas Group 2 had 32 (20%) nonsurgical-site infections. This difference, however, was not statistically significant (p = 0.16). Only the total number of blood units transfused and the presence of a PATI score greater than or equal to 25 were found to be independently associated with the development of a postoperative surgical- and nonsurgical-site infections (p = 0.001 and p = 0.003, respectively). Of note, the presence of a colon injury was not found to be an independent risk factor (p = 0.11) for either surgical or nonsurgical site postoperative infection in our study.

CONCLUSION

High-risk patients with colon or other hollow viscus injuries from penetrating abdominal trauma are at no greater risk for surgical-site or nonsurgical-site infection when treated with only a 24-hour course of a broad-spectrum antibiotic.

Short-term prophylaxis in clean-contaminated surgery

Postoperative infections are not consistently controlled by current practice measures. From a recent study of 12,384 patients, postoperative infection occurred in 22% of colorectal procedures and 25% of upper gastrointestinal procedures. Infections were associated with a higher death rate, longer hospitalization, and more intense post-discharge care. Control of infections for clean-contaminated procedures requires effective bowel cleansing when appropriate, meticulous surgical technique, and timely antimicrobial administration. Many patients undergoing clean-contaminated surgery do not receive properly timed antimicrobials. Although the comparative value of oral (neomycin and erythromycin) or parenteral antimicrobials for colon surgery remains an unresolved issue, the combination can be beneficial for many colorectal operations. Third generation cephalosporins are not consistently more effective than older agents such as cefoxitin and increase bacterial resistance. Improper antimicrobial timing is one of the most common problems with surgical prophylaxis and is fully under the control of the surgeon. To maximize benefits of antimicrobial prophylaxis, systems should be devised to assure timely administration.

New advances in the use of antimicrobial agents in surgery: intra-abdominal infections

Advances in both technical methods and antimicrobial therapy have significantly reduced morbidity and mortality for secondary (enterogenous) or community-acquired intra-abdominal infections. Presumptive antimicrobial therapy for most community-acquired intra-abdominal infection can be safely initiated with a single broad-spectrum antimicrobial effective against the expected Enterobacteriaceae and anaerobic flora. Beta-lactams and carbapenems are effective against gram-negative rods and anaerobes, achieve therapeutic levels rapidly, and have low toxicity in the absence of penicillin allergy. Second generation cephalosporins (e.g. cefoxitin and cefotetan) remain useful in surgical prophylaxis and treatment of mild community-acquired pneumonia, but limitations in their spectra and antimicrobial resistance restrict their utility in more serious infections. The fourth generation cephalosporins are also effective, but should be combined with other antimicrobials such as metronidazole for adequate anaerobic coverage. Preliminary data on new fluoroquinolones are scant, but promising results were obtained in one clinical trial. We predict the current trend toward the use of broad-spectrum single agent antimicrobials for therapy of intra-abdominal infection will continue.

The role of beta-lactam/beta-lactamase inhibitors in the management of mixed infections

Microbiological studies show that the in vitro antimicrobial activity of sulbactam-ampicillin encompasses not only gram-positive and gram-negative aerobes, but also anaerobes. Such a broad spectrum of activity suggests its suitability as monotherapy for the empiric management of polymicrobial infections. Typical mixed infections, which are frequently life-threatening, include those occurring in the abdomen or pelvis, diabetic foot infections, and brain abscess. Numerous comparative clinical studies have revealed the clinical and bacteriological efficacy of sulbactam-ampicillin to be comparable to that of imipenem cilastatin and the second-generation cephalosporins cefoxitin and cefotetan. In addition, other studies have demonstrated that sulbactam-ampicillin monotherapy is cost-beneficial. A reduction in the duration of hospitalization, the lack of potentially toxic side-effects, and lower drug costs associated with monotherapy all contribute to the cost-effectiveness of sulbactam-ampicillin.

The duration of antibiotic administration in penetrating abdominal trauma

BACKGROUND

The epidemiology of penetrating abdominal trauma is changing to reflect an increasing incidence of multiple injuries. Not only do multiple injuries increase the risk of infection, a very high risk of serious infection is conferred by immunosuppression from hemorrhage and transfusion and the high likelihood of intestinal injury, especially to the colon. Optimal timing and choice of presumptive antibiotic therapy has been established for penetrating trauma, but duration has not been studied extensively in such seriously injured patients. The purpose of this study was to test the hypothesis that 24 hours of antibiotic therapy remains sufficient to reduce the incidence of infection in penetrating abdominal trauma.

METHODS

Three hundred fourteen consecutive patients with penetrating abdominal trauma were prospectively randomized into two groups: Group I received 24 hours of intravenous cefoxitin (1 g q6h) and group II received 5 days of intravenous cefoxitin. The development of a deep surgical site (intra-abdominal) infection as well as any type of nosocomial infection, as defined by the Centers for Disease Control and Prevention, (ie, surgical site infections, catheter-related infections, urinary tract, pneumonia), was recorded. Hospital length of stay was a secondary endpoint. Statistical analysis included chi-square tests for coordinate variables and two-tailed unpaired t tests for continuous variables. The independence of risk factors for the development of infection was assessed by multivariate analysis of variance. Significance was determined when P <0.05.

RESULTS

Three hundred patients were evaluable. There was no postoperative mortality, and no differences in overall length of hospitalization between groups. The duration of antibiotic treatment had no influence on the development of any infection (P = 0.136) or an intraabdominal infection (P = 0.336). Only colon injury was an independent predictor of the development of an intraabdominal infection (P = 0.0031). However, the overall infection incidence was affected by preoperative shock (P = 0.003), colon (P = 0.0004), central nervous system (CNS) injuries (P = 0.031), and the number of injured organs (P = 0.026). Several factors, including intraoperative shock (P = 0.021) and injuries to the colon (P = 0.0008), CNS (P = 0.0001), and chest (P = 0.0006), were independent contributors to prolongation of the hospital stay.

CONCLUSIONS

Twenty-four hours of presumptive intravenous cefoxitin versus 5 days of therapy made no difference in the prevention of postoperative infection or length of hospitalization. Infection was associated with shock on admission to the emergency department, the number of intra-abdominal organs injured, colon injury specifically, and injury to the central nervous system. Intra-abdominal infection was predicted only by colon injury. Prolonged hospitalization was associated with intraoperative shock and injuries to the chest, colon, or central nervous system.

Definition of the role of enterococcus in intraabdominal infection: analysis of a prospective randomized trial

BACKGROUND

The role of enterococcus in intraabdominal infection is controversial. This study examines the contribution of enterococcus to adverse outcome in a large intraabdominal infection trial.

METHODS

A randomized prospective double-blind trial was performed to compare two different antimicrobial regimens in combination with surgical or percutaneous drainage in the treatment of complicated intraabdominal infections. A total of 330 valid patients was enrolled from 22 centers in North America.

RESULTS

In 330 valid patients, 71 had enterococcus isolated from the initial drainage of an intraabdominal focus of infection. This finding was associated with a significantly higher treatment failure rate than that of patients without enterococcus (28% versus 14%, p < 0.01). In addition, only Acute Physiology and Chronic Health Evaluation II score and presence of enterococcus were significant independent predictors of treatment failure when stepwise logistic regression was performed (p < 0.01 and < 0.03). Risk factors for the presence of enterococcus include age, Acute Physiology and Chronic Health Evaluation II, preinfection hospital length of stay, postoperative infections, and anatomic source of infection. There was no difference between the clinical trial treatment regimens with regard to overall failure, failure associated with enterococcus, or frequency of enterococcal isolation.

CONCLUSIONS

This study is the first to report enterococcus as a predictor of treatment failure in complicated intraabdominal infections. This trial also identifies several significant risk factors for the presence of enterococcus in such infections.

Unnecessary laparotomies for trauma: a prospective study of morbidity

OBJECTIVE

Despite advances in diagnostic techniques, unnecessary laparotomies (no repairs/no drains) are still performed in trauma centers. The true risks of such procedures are unclear. Our hypothesis was that the overall incidences of complications after an unnecessary laparotomy for trauma that have been reported in the literature were significant underestimates because of flaws in study design. To test our hypothesis, a prospective study to record all perioperative complications in patients undergoing an unnecessary laparotomy for trauma was performed.

DESIGN

Prospective case series.

MEASUREMENTS AND MAIN RESULTS

The main outcome measures were perioperative complications. An unnecessary laparotomy was performed in 254 patients who sustained trauma. The mechanism of injury was a penetrating wound in 98% of the patients. Complications occurred in 41.3% of the patients (n = 105) and included atelectasis (15.7%), postoperative hypertension that required medical treatment (11.0%), pleural effusion (9.8%), pneumothorax (5.1%), prolonged ileus (4.3%), pneumonia (3.9%), surgical wound infection (3.2%), small bowel obstruction (2.4%), urinary infection (1.9%), and others. Complication rates for patients who did (n = 111) and did not (n = 143) have an associated injury were 61.3% and 25.9%, respectively (p = 0.0001). Complications occurred in 19.7% of 81 patients who did not have an associated injury and who did not have intraperitoneal or retroperitoneal penetration. The mortality rate for the entire series was 0.8% and was unrelated to the unnecessary laparotomies.

CONCLUSIONS

Unnecessary laparotomies for trauma result in a significant morbidity when complications are recorded prospectively. Current efforts to reduce the incidence of these unnecessary procedures without increasing that of missed injuries are obviously worthwhile.

Postsurgical complications in older patients. The role of pharmacological intervention

The number of elderly patients undergoing surgery has been rapidly increasing during the last few years. Following surgical interventions, high rates of mortality and morbidity have been reported in the most advanced age groups. Nevertheless, perioperative evaluation and postoperative care are the major determinants of the overall outcome. Postsurgical complications are common in advanced age, since multiple pathology is often present in geriatric patients. Furthermore, the decreased efficiency of homeostatic mechanisms may facilitate the development of multiple organ failure (MOF), even as a consequence of apparently slight alterations in immune, cardiac or respiratory systems. Thus, prompt recognition and treatment of any complication often prevents the development of irreversible conditions. While cardiac and pulmonary complications account for 50% of early postoperative adverse events, infections, thromboembolism, renal failure, stress ulcers and coagulation disorders may occur well after surgical procedures. An important part of postoperative geriatric care is the diagnosis and correction of fluid, electrolyte and acid-base disturbances. These disturbances may manifest as mild, atypical signs, such as slight neuromuscular depression or delirium. Yet, they often constitute life-threatening conditions that should be rapidly and properly corrected. Finally, it should be remembered that, due to the frequent use of multiple drugs, elderly patients are at high risk of developing adverse drug reactions. Thus, the treatment of postoperative complications requires a strong rational effort to disentangle the combined effects of aging, drugs and pathology.