Management of intra-abdominal infections. The case for intraoperative cultures and comprehensive broad-spectrum antibiotic coverage. The Canadian Intra-abdominal Infection Study Group

Antimicrobial Challenge in Acute Care Surgery

The burden of infections in acute care surgery (ACS) is huge. Surgical emergencies alone account for three million admissions per year in the United States (US) with estimated financial costs of USD 28 billion per year. Acute care facilities and ACS patients represent boost sanctuaries for the emergence, development and transmission of infections and multi-resistant organisms. According to the World Health Organization, healthcare-associated infections affected around 4 million cases in Europe and 1.7 million in the US alone in 2011 with 39,000 and 99,000 directly attributable deaths, respectively. In this scenario, antimicrobial resistance arose as a public-health emergency that worsens patients’ morbidity and mortality and increases healthcare costs. The optimal patient care requires the application of comprehensive evidence-based policies and strategies aiming at minimizing the impact of healthcare associated infections and antimicrobial resistance, while optimizing the treatment of intra-abdominal infections. The present review provides a snapshot of two hot topics, such as antimicrobial resistance and systemic inflammatory response, and three milestones of infection management, such as source control, infection prevention, and control and antimicrobial stewardship.

Teicoplanin versus β-lactam for febrile patients with Staphylococcus-like bacteremia: focus on methicillin-susceptible Staphylococcus aureus bacteremia

Background

Many studies have shown that vancomycin is inferior to β-lactam antibiotics in terms of effectiveness in the treatment of methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia. However, limited data are available regarding the comparison of clinical outcomes between patients receiving initial teicoplanin and those receiving β-lactam antibiotics for MSSA bacteremia.

Methods

Eighty-four adults with MSSA bacteremia were included: initial teicoplanin treatment group (n = 28) and β-lactam treatment group (n = 56). The two groups were further stratified based on propensity score matching according to the outcome analysis using a logistic regression model. We investigated the clinical outcomes between the groups before and after propensity score matching after treatment completion.

Results

Pittsburgh bacteremia score ≥ 4 (odds ratio, 60.6; 95%CI, 7.4–496.8) was an independent risk factor for unfavorable outcome. After propensity score matching, the initial teicoplanin treatment group and the β-lactam treatment group consisted of 28 patients each. No statistically significant differences were observed in the proportions of patients with favorable outcomes and 30-day overall mortality rates between the groups before and after propensity score matching after the completion of teicoplanin or β-lactam treatment. The Kaplan-Meier 30-day survival curve also showed no significant difference between the patients receiving initial teicoplanin treatment and those receiving β-lactam treatment before and after matching (hazard ratio, 1.84, 95%CI, 0.60–5.64; and 3.12, 95%CI, 0.98–9.99, respectively).

Conclusions

There were no significant difference in clinical outcomes between initial teicoplanin treatment and β-lactam treatment among patients with MSSA bacteremia. Pittsburgh bacteremia score ≥ 4 was a significant risk factor for mortality.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06111-w.

Diagnosis and Management of Intraabdominal Infection: Guidelines by the Chinese Society of Surgical Infection and Intensive Care and the Chinese College of Gastrointestinal Fistula Surgeons

The Chinese guidelines for IAI presented here were developed by a panel that included experts from the fields of surgery, critical care, microbiology, infection control, pharmacology, and evidence-based medicine. All questions were structured in population, intervention, comparison, and outcomes format, and evidence profiles were generated. Recommendations were generated following the principles of the Grading of Recommendations Assessment, Development, and Evaluation system or Best Practice Statement (BPS), when applicable. The final guidelines include 45 graded recommendations and 17 BPSs, including the classification of disease severity, diagnosis, source control, antimicrobial therapy, microbiologic evaluation, nutritional therapy, other supportive therapies, diagnosis and management of specific IAIs, and recognition and management of source control failure. Recommendations on fluid resuscitation and organ support therapy could not be formulated and thus were not included. Accordingly, additional high-quality clinical studies should be performed in the future to address the clinicians' concerns.

Clinical implications of multidrug-resistant microorganisms and fungi isolated from patients with intra-abdominal infections in the Republic of Korea: a multicenter study

The purpose of this study was to evaluate the clinical significance of fungi and multidrug-resistant organisms (MDROs) isolated from patients with intra-abdominal infections (IAIs). This multicenter study included consecutive patients admitted for microbiologically proven IAIs at 6 university-affiliated hospitals in South Korea between 2016 and 2018. A total of 1571 patients were enrolled. Multivariable logistic regression analysis revealed that the isolation of MDROs, isolation of Candida spp., underlying renal diseases, Charlson comorbidity score ≥ 3, septic shock, failure to receive a required surgery or invasive intervention, secondary bacteremia due to IAIs, and lower body mass index were found to be independent predictors for 28-day mortality. However, the isolation of Enterococcus spp. was not identified as a significant risk factor. MDROs and Candida spp. were found in 42 (2.7%) and 395 (25.1%), patients respectively. The isolation of MDROs or Candida spp. was a surrogate marker of 28-day mortality.

Outcome and Adequacy of Empirical Antibiotherapy in Post-Operative Peritonitis: A Retrospective Study

Background: Empirical antibiotherapy (EA) should target all bacteria in post-operative peritonitis (PP). Nevertheless, recent studies failed to prove a link between adequacy of EA and prognosis of PP. We sought to confirm this loss of association between adequate EA and prognosis and to analyze the evolution of patients' characteristics and antimicrobial strategies. Methods: This is was retrospective study. Patients with a positive fungal culture were excluded. The cohort was divided into two time periods. Data of survivors and non-survivors were compared within each time period. Differences between the two periods were assessed. A multivariable analysis searched for parameters associated with a higher hospital mortality rate. Results: Two hundred fifty-one patients were included, with 92 patients in the first period (P1) and 152 patients in the second period (P2). Inadequate EA was associated with a worse outcome only in P1. The multivariable analysis in the whole cohort showed that inadequate EA was associated with a higher mortality rate. When the differences noticed between the two periods were entered in the model (presence of resistant gram-positive cocci and EA comprising glycopeptides), inadequate EA was no longer associated with worse outcome. In P1, the most severe patients had more resistant bacteria, hence, had a higher rate of inadequate EA. This artifact disappeared in P2, during which broader antibiotherapies with triple EA were more often prescribed for the most severe patients. Conclusion: This study showed that the link between inadequate EA and outcome of patients with PP was at least partly artifactual in older studies.

Intra-abdominal infections: the role of different classifications on the selection of the best antibiotic treatment

Background

Intra-abdominal infections (IAIs) represent a most frequent gastrointestinal emergency and serious cause of morbimortality. A full classification, including all facets of IAIs, does not exist. Two classifications are used to subdivide IAIs: uncomplicated or complicated, considering infection extent; and community-acquired, healthcare-associated or hospital-acquired, regarding the place of acquisition. Adequacy of initial empirical antibiotic therapy prescribed is an essential need. Inadequate antibiotic therapy is associated with treatment failure and increased mortality. This study was designed to determine accuracy of different classifications of IAIs to identify infections by pathogens sensitive to current treatment guidelines helping the selection of the best antibiotic therapy.

Methods

A retrospective cohort study including all adult patients discharged from hospital with a diagnosis of IAI between 1st of January and 31st of October, 2016. All variables potentially associated with pre-defined outcomes: infection by a pathogen sensitive to non-pseudomonal cephalosporin or ciprofloxacin plus metronidazole (ATB 1, primary outcome), sensitive to piperacillin-tazobactam (ATB 2) and hospital mortality (secondary outcomes) were studied through logistic regression. Accuracy of the models was assessed by area under receiver operating characteristics (AUROC) curve and calibration was tested using the Hosmer-Lemeshow goodness-of-fit test.

Results

Of 1804 patients screened 154 met inclusion criteria. Sensitivity to ATB 1 was independently associated with male gender (adjusted OR = 2.612) and previous invasive procedures in the last year (adjusted OR = 0.424) (AUROC curve = 0,65). Sensitivity to ATB 2 was independently associated with liver disease (adjusted OR = 3.580) and post-operative infections (adjusted OR = 2.944) (AUROC curve = 0.604). Hospital mortality was independently associated with age ≥ 70 (adjusted OR = 4.677), solid tumour (adjusted OR = 3.127) and sensitivity to non-pseudomonal cephalosporin or ciprofloxacin plus metronidazole (adjusted OR = 0.368).

The accuracy of pre-existing classifications to identify infection by a pathogen sensitive to ATB 1 was 0.59 considering place of acquisition, 0.61 infection extent and 0.57 local of infection, for ATB 2 it was 0.66, 0.50 and 0.57, respectively.

Conclusion

None of existing classifications had a good discriminating power to identify IAIs caused by pathogens sensitive to current antibiotic treatment recommendations. A new classification, including patients’ individual characteristics like those included in the current model, might have a higher potential to distinguish IAIs by resistant pathogens allowing a better choice of empiric antibiotic therapy.

Daptomycin versus teicoplanin for bloodstream infection due to methicillin-resistant Staphylococcus aureus with a high teicoplanin minimal inhibitory concentration ≥1.5 mg/L: a propensity score-based analysis

Background

Recent reports have described decreased effectiveness of teicoplanin in the treatment of bacteremia due to methicillin-resistant Staphylococcus aureus (MRSA) with teicoplanin minimal inhibitory concentration (MIC) ≥1.5 mg/L. Consensus guidelines recommend considering use of alternative agents for MRSA infections involving a higher teicoplanin MIC, despite of limited data to support this recommendation.

Patients and methods

To compare the clinical outcome among patients with bacteremia due to MRSA with teicoplanin MIC ≥1.5 mg/L, we included patients who received high-dose daptomycin (≥8 mg/kg/day) and those who received standard-dose (6 mg/kg/day) or high-dose (6 mg/kg/12 hours) maintenance teicoplanin. The primary endpoint was a favorable outcome, defined as the resolution of clinical signs and symptoms and a negative culture report at the end of therapy. Adjusted analyses were performed by multivariate analysis and propensity score-based matching.

Results

Of 142 patients eligible for inclusion, 28 (19.7%) were treated with high-dose daptomycin, 27 (19.0%) with high-dose teicoplanin, and 87 (61.3%) with standard-dose teicoplanin. In multivariate regression analysis, Pittsburgh bacteremia score ≥4 (OR, 5.3; 95%CI, 1.9-14.5) was independently associated with an unfavorable outcome. After propensity-score matching with age and Pittsburgh bacteremia score ≥4, patients on high-dose daptomycin were more likely to have favorable outcomes than those on standard-dose teicoplanin (74.1% vs 42.6%; P=0.02). However, there was no significant difference in terms of favorable outcomes (P=0.12) between patients receiving high-dose daptomycin and those receiving high-dose teicoplanin after the same propensity-score matching.

Conclusion

Treatment with high-dose daptomycin resulted in significantly better outcomes than with standard-dose teicoplanin in the treatment of MRSA bacteremia with teicoplanin MIC ≥1.5 mg/L. However, the clinical outcome of the patients receiving high-dose teicoplanin was similar to that of the patients receiving high-dose daptomycin.

Impact of teicoplanin maintenance dose and MIC values on the clinical outcomes of patients treated for methicillin-resistant Staphylococcus aureus bacteremia

Objectives

Teicoplanin, a glycopeptide, is regarded as among the drug choices for methicillin-resistant Staphylococcus aureus (MRSA) infections. Few studies have evaluated the relationship between teicoplanin minimal inhibitory concentrations (MICs) and outcomes among patients with serious MRSA infections.

Subjects and methods

We investigated the relationship between teicoplanin maintenance dose and clinical outcomes, on the completion of teicoplanin therapy, in bacteremia patients with MRSA infection, with different teicoplanin MICs. A total of 146 adult patients with MRSA bacteremia were enrolled at Kaohsiung Chang Gung Memorial Hospital between September 2012 and September 2015.

Results

A higher number of patients in the high-dose regimen group (6 mg/kg/12 h) had favorable outcomes than those in the standard-dose regimen group (6 mg/kg/24 h) (84.1% vs 41.2%; p<0.01), regardless of the teicoplanin MICs. In the multivariate analysis, a Pittsburgh bacteremia score ≥4 (OR, 0.07, 95% CI, 0.03–0.19) was a risk factor for an unfavorable final clinical response, whereas high-dose teicoplanin maintenance therapy for MRSA bacteremia was significantly associated with a favorable final response (OR, 25.3 [95% CI, 4.43–144.03] for isolates with a teicoplanin MIC ≥1.5 mg/L and OR, 5.6 [95% CI, 1.57–19.91] for isolates with a teicoplanin MIC <1.5 mg/L). Survival at 30 days was significantly better for patients receiving high-dose teicoplanin maintenance treatment, regardless of the teicoplanin MICs of the MRSA isolates. Patients were selected using propensity score matching, based on the independent predictors of a favorable final outcome. After appropriate propensity score matching, patients in the high-dose regimen group still had a statistically significant favorable outcome at the end of treatment (84.1% vs 40.9%; p<0.01).

Conclusion

The results suggested that high-dose teicoplanin maintenance treatment is associated with more favorable outcomes than standard-dose teicoplanin maintenance treatment, for patients with MRSA bacteremia, regardless of the teicoplanin MIC.

Epidemiology and Risk Factors for Isolation of Multi-Drug-Resistant Organisms in Patients with Complicated Intra-Abdominal Infections

BACKGROUND

Patients with complicated intra-abdominal infections (cIAIs) caused by multi-drug-resistant organisms (MDROs) have been identified as being at increased risk for adverse outcomes. Prompt identification and stratification of these patients is essential in the clinical management, allowing the physician timely optimization of empiric antimicrobial therapy while awaiting results of intra-operative cultures to streamline antibiotic treatment.

METHODS

The study is a secondary analysis from two prospective multi-center color surveillance studies. It included all consecutively hospitalized adult patients undergoing surgical procedures, interventional drainage, or conservative treatment with cIAIs, with positive cultures performer on intra-operative samples of peritoneal fluid or purulent exudate/discrete abscesses. Patients with pancreatitis and primary peritonitis were excluded. A case-control approach has been used to evaluate the factors associated with the isolation of a MDRO in enrolled patients.

RESULTS

Among 1986 patients included in the study, a total of 3534 micro-organisms were isolated from intra-peritoneal fluid samples; in 46.5% of cultures, two or more pathogens were identified. The MDROs represented 9.8% of the total of isolated micro-organisms. The overall incidence rate of MDROs was 13.9%. The MDROs were more frequently isolated in patients with health-care-associated cIAIs (25.4%). Multi-nomial logistic regression analysis of risk factors demonstrated that statistically significant risk factors independently associated with the occurrence of MDROs were previous antimicrobial therapy administered within seven days before operation, presence of severe cardiovascular disease, white blood cell count <4000/mL or >12,000/mL, cIAI acquired in a healthcare setting, and inadequate source control.

CONCLUSIONS

The study showed that knowledge of five easily recognizable variables-assessable on hospital admission or as soon as the surgical intervention is concluded-might guide the surgeon to identify patients with cIAIs caused by MDROs, and therefore to choose the most adequate empiric antimicrobial therapy for them.

The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection

BACKGROUND

Previous evidence-based guidelines on the management of intra-abdominal infection (IAI) were published by the Surgical Infection Society (SIS) in 1992, 2002, and 2010. At the time the most recent guideline was released, the plan was to update the guideline every five years to ensure the timeliness and appropriateness of the recommendations.

METHODS

Based on the previous guidelines, the task force outlined a number of topics related to the treatment of patients with IAI and then developed key questions on these various topics. All questions were approached using general and specific literature searches, focusing on articles and other information published since 2008. These publications and additional materials published before 2008 were reviewed by the task force as a whole or by individual subgroups as to relevance to individual questions. Recommendations were developed by a process of iterative consensus, with all task force members voting to accept or reject each recommendation. Grading was based on the GRADE (Grades of Recommendation Assessment, Development, and Evaluation) system; the quality of the evidence was graded as high, moderate, or weak, and the strength of the recommendation was graded as strong or weak. Review of the document was performed by members of the SIS who were not on the task force. After responses were made to all critiques, the document was approved as an official guideline of the SIS by the Executive Council.

RESULTS

This guideline summarizes the current recommendations developed by the task force on the treatment of patients who have IAI. Evidence-based recommendations have been made regarding risk assessment in individual patients; source control; the timing, selection, and duration of antimicrobial therapy; and suggested approaches to patients who fail initial therapy. Additional recommendations related to the treatment of pediatric patients with IAI have been included.

SUMMARY

The current recommendations of the SIS regarding the treatment of patients with IAI are provided in this guideline.

Selected Topics in Anaerobic Bacteriology

Alteration in the host microbiome at skin and mucosal surfaces plays a role in the function of the immune system, and may predispose immunocompromised patients to infection. Because obligate anaerobes are the predominant type of bacteria present in humans at skin and mucosal surfaces, immunocompromised patients are at increased risk for serious invasive infection due to anaerobes. Laboratory approaches to the diagnosis of anaerobe infections that occur due to pyogenic, polymicrobial, or toxin-producing organisms are described. The clinical interpretation and limitations of anaerobe recovery from specimens, anaerobe-identification procedures, and antibiotic-susceptibility testing are outlined. Bacteriotherapy following analysis of disruption of the host microbiome has been effective for treatment of refractory or recurrent Clostridium difficile infection, and may become feasible for other conditions in the future.

Impact of a Dynamic Microbiological Environment on the Clinical Efficacy of Ertapenem and Piperacillin/Tazobactam in the Treatment of Complicated Community-Acquired Intra-Abdominal Infection in Spain: A Cost-Consequence Analysis

BACKGROUND AND OBJECTIVE

The microbial susceptibility of many antibiotics has been affected by prescribing patterns and their extensive use. The purpose of this evaluation was to assess how these changes could affect the initial efficacy of ertapenem and piperacillin/tazobactam in the treatment of complicated intra-abdominal infections (IAIs) acquired in the community and the potential consequences this may have in healthcare costs in Spain.

METHODS

The Initial efficacy of ertapenem and piperacillin/tazobactam for patients with APACHE (Acute Physiology and Chronic Health Evaluation) II scores <10 was extracted from a multicenter randomized study and were combined with the current microbial susceptibilities obtained from the SMART study, a multinational surveillance program. Country-specific pathogens distribution was extracted from a national study in patients with community-acquired IAI. The estimated effectiveness was used in a decision-analytic model to compare total costs between ertapenem and piperacillin/tazobactam in the treatment of complicated IAI. The model performs extensive one-way and probabilistic sensitivity analyses.

RESULTS

The model suggested a savings of €209 (year 2012 values) per patient when complicated IAIs acquired in the community (APACHE II <10) were treated with ertapenem instead of piperacillin/tazobactam. One-way sensitivity analyses showed length of stay as the key driver parameter. Further analysis of this parameter and probabilistic sensitivity analysis confirmed the robustness of our evaluation, with a 58% likelihood of ertapenem being dominant.

CONCLUSIONS

Ertapenem appears to be a cost-saving strategy over piperacillin/tazobactam for the treatment of patients with complicated IAIs acquired in the community in Spain.

Fungal Culture Positivity in Patients with Perforation Peritonitis

BACKGROUND

Perforation peritonitis is the most common surgical emergency. A large number of microorganisms have been cultured from the abdominal fluid obtained from patients with gastrointestinal perforation peritonitis. The present study was undertaken to determine the frequency of positive fungal culture in perforation peritonitis as Candida co-infection is reported to be a bad prognostic factor in these patients.

MATERIALS AND METHODS

The intraoperative specimens of abdominal fluid collected during laparotomy from 140 consecutive patients of gastro-intestinal perforation were analysed by microbial culture for bacteria and fungi. Their antimicrobial susceptibility was also studied.

RESULTS

The mean presenting age of the patients was 35 years and 120 (85.7%) of them were males. Aerobic Gram Negative Bacilli (AGNB) were observed in 82 (79.6%) of the culture positive abdominal fluid specimens, of which 58 (70.7%) were Escherichia coli. Gram negative bacteria were most frequently isolated from colorectal perforation (100%) while Gram positive bacteria were from upper gastrointestinal perforation (47.2%). Candida was cultured in as many as 68 of 140 (48.6%) specimens. Its prevalence was highest in patients with gastroduodenal perforation (70.5%) and was altogether absent in patients having appendicular perforation.

CONCLUSION

High prevalence of fungal culture positivity of peritoneal fluid of patients of perforation peritonitis shows that along with the bacterial culture, fungal cultures should always be asked for in such patients. Adequate and timely antimicrobial treatment including treatment of fungal infection could help reduce mortality in this group of patients.

Risk factors for acquisition of multidrug-resistant bacteria in patients with anastomotic leakage after colorectal cancer surgery

PURPOSE

The risk factors for acquiring an infection with multidrug-resistant (MDR) bacteria in patients with anastomotic leakage after colorectal cancer surgery are poorly understood. We evaluated the risk factors associated with the initial acquisition of MDR pathogens in patients with anastomotic leakage after colorectal cancer surgery.

METHODS

This study was a retrospective review of prospectively collected data at a university affiliated-tertiary referral hospital in South Korea. From January 2009 to April 2013, a total of 6767 consecutive patients with colorectal cancer who underwent surgery were registered. Of these patients, 190 (2.8%) were diagnosed with anastomotic leakage. Finally, 143 (2.1%) patients with culture test results were included in this study.

RESULTS

Of the 143 enrolled patients, 46 (32.2%) were classified in the MDR group. The use of antibiotics for more than 5 days before diagnosis of anastomosis site leakage (p = 0.016) and diabetes mellitus (p = 0.028) was identified as independent risk factors for MDR acquisition by multivariate analysis. The rate of adequate initial empirical antibiotic therapy in the MDR group was lower than in the non-MDR group (35 vs. 75%, p < 0.001). Furthermore, the duration of antibiotic administration after the leak was longer in the MDR group (p = 0.013). Patients in the MDR group also had a longer hospital stay (p = 0.012).

CONCLUSIONS

The length of antibiotic administration before the diagnosis of anastomotic leakage and diabetes mellitus were risk factors associated with the acquisition of MDR bacteria in patients with anastomotic leakage after colorectal cancer surgery.

The risk of seizures among the carbapenems: a meta-analysis

OBJECTIVES

A consensus exists among clinicians that imipenem/cilastatin is the most epileptogenic carbapenem, despite inconsistencies in the literature.

METHODS

We conducted a meta-analysis of all randomized controlled trials comparing carbapenems with each other or with non-carbapenem antibiotics to assess the risk of seizures for imipenem, meropenem, ertapenem and doripenem.

RESULTS

In the risk difference (RD) analysis, there were increased patients with seizure (2 per 1000 persons, 95% CI 0.001, 0.004) among recipients of carbapenems versus non-carbapenem antibiotics. This difference was largely attributed to imipenem as its use was associated with an additional 4 patients per 1000 with seizure (95% CI 0.002, 0.007) compared with non-carbapenem antibiotics, whereas none of the other carbapenems was associated with increased seizure. Similarly, in the pooled OR analysis, carbapenems were associated with a significant increase in the risk of seizures relative to non-carbapenem comparator antibiotics (OR 1.87, 95% CI 1.35, 2.59). The ORs for risk of seizures from imipenem, meropenem, ertapenem and doripenem compared with other antibiotics were 3.50 (95% CI 2.23, 5.49), 1.04 (95% CI 0.61, 1.77), 1.32 (95% CI 0.22, 7.74) and 0.44 (95% CI 0.13, 1.53), respectively. In studies directly comparing imipenem and meropenem, there was no difference in epileptogenicity in either RD or pooled OR analyses.

CONCLUSIONS

The absolute risk of seizures with carbapenems was low, albeit higher than with non-carbapenem antibiotics. Although imipenem was more epileptogenic than non-carbapenem antibiotics, there was no statistically significant difference in the imipenem versus meropenem head-to-head comparison.

Initial microbial spectrum in severe secondary peritonitis and relevance for treatment

This study aims to determine whether abdominal microbial profiles in early severe secondary peritonitis are associated with ongoing infection or death. The study is performed within a randomized study comparing two surgical treatment strategies in patients with severe secondary peritonitis (n = 229). The microbial profiles of cultures retrieved from initial emergency laparotomy were tested with logistic regression analysis for association with ‘ongoing infection needing relaparotomy’ and in-hospital death. No microbial profile or the presence of yeast or Pseudomonas spp. was related to the risk of ongoing infection needing relaparotomy. Resistance to empiric therapy for gram positive cocci and coliforms was moderately associated with ongoing abdominal infection (OR 3.43 95%CI 0.95–12.38 and OR 7.61, 95%CI 0.75–76.94). Presence of only gram positive cocci, predominantly Enterococcus spp, was borderline independently associated with in-hospital death (OR 3.69, 95%CI 0.99–13.80). In secondary peritonitis microbial profiles do not predict ongoing abdominal infection after initial emergency laparotomy. However, the moderate association of ongoing infection with resistance to the empiric therapy compels to more attention for resistance when selecting empiric antibiotic coverage.

Treatment of complicated intra-abdominal infections in the era of multi-drug resistant bacteria

The management of severe intra-abdominal infections remains a major challenge facing surgeons and intensive care physicians, because of its association with high morbidity and mortality. Surgical management and intensive care medicine have constantly improved, but in the recent years a rapidly continuing emergence of resistant pathogens led to treatment failure secondary to infections with multi-drug resistant bacteria. In secondary peritonitis the rate of resistant germs at the initial operation is already 30%. The lack of effective antibiotics against these pathogens resulted in the development of new broad-spectrum compounds and antibiotics directed against resistant germs. But so far no "super-drug" with efficacy against all resistant bacteria exists. Even more, soon after their approval, reports on resistance against these novel drugs have been reported, or the drugs were withdrawn from the market due to severe side effects. Since pharmaceutical companies reduced their investigations on antibiotic research, only few new antimicrobial derivates are available.

In abdominal surgery you may be in fear that in the future more and more patients with tertiary peritonitis secondary to multi-drug resistant species are seen with an increase of mortality after secondary peritonitis.

This article reviews the current treatment modalities for complicated intra-abdominal infections with special reference to the antibiotic treatment of complicated intra-abdominal infections with multi-drug resistant species.

Perioperative use of antibiotics in intra-abdominal surgical infections

BACKGROUND

We created a questionnaire with the aim of evaluating surgeon compliance with the guidelines for antibiotic use in the perioperative period in intra-abdominal surgical infections. We discuss the problems emerging from non-adherence to these guidelines.

METHODS

In the questionnaire, we tried to correlate the type of intra-abdominal infection with: (1) Time of antibiotic administration commencement; (2) type of antibiotic(s) administered; (c) duration of antibiotic administration; and (4) modification of antibiotic type/duration of administration in the presence of factors increasing the risk of treatment failure. In order to collect and process the data more easily, the patients were divided into four groups-Group A: Community patients with intra-abdominal surgical infections and simple contamination of the peritoneal cavity according to the Surgical Infection Society (SIS) guidelines; Group B: Community patients with an intra-abdominal surgical infection evolving to secondary peritonitis per SIS guidelines; Group C: Community patients with an intra-abdominal surgical infection with a high risk of surgical site infection; and Group D: Patients with recent hospitalization or nosocomial or postoperative intra-abdominal infection.

RESULTS

The questionnaire was sent to the directors of 43 surgical clinics in northern Greece, and 27 answered (63%). In 81.5% of the clinics (median 22; range 15-24), depending on the type of infection, empirical antibiotic treatment commenced preoperatively. In Group A, on average, 29.6% of the clinics (median 8; range 5-16) administer antibiotics for as long as 24 h, and 11.1% (median 3; range 1-10) use antibiotics not recommended in the SIS guidelines (e.g., third- and fourth-generation cephalosporins, ciprofloxacin, imipenem-cilastatin, meropenem, or piperacillin/tazobactam). In Group B, 22.2% of clinics (median 6; range 2-15) administer antibiotics for three to five days, and 14.8% (median 4; range 1-11) use antibiotics outside SIS guidelines. In Group C, 40.7% of clinics (median 11; range 1-14) administer antibiotics for more than five days, and 14.8% (median 4; range 1-14) use antibiotics that are outside the SIS guidelines. In Group D, 11.1% of clinics (median 3; range 2-5) do not cover Enterococcus with the antibiotics administered.

CONCLUSIONS

There seems to be confusion in determining the situations with simple contamination of the peritoneal cavity, whose treatment requires short-duration antibiotic administration, and in the type of antibiotics administered to various patient groups, elements that lead to prolonged or erroneous administration of antibiotic drugs. Continuous discussion and surgeon training is imperative and may be the best choice to ensure familiarity with antibiotics and their proper use and thus to minimize serious adverse events and treatment failure.

Prevalence of fecal carriage of antibiotic-resistant bacteria in patients with acute surgical abdominal infections

OBJECTIVE

Antibiotic resistance is increasing worldwide. The aims of the current study were to determine the fecal carriage of antibiotic-resistant bacteria and antibiotic treatment in surgical patients admitted to hospital due to acute intra-abdominal infections.

MATERIALS AND METHODS

Eight Swedish surgical units participated in this prospective multicenter investigation. Rectal swabs were obtained on admission to hospital. Cultures were performed on chromogenic agar and antibiotic susceptibility testing was performed using the disk diffusion method. Extended-spectrum beta-lactamase (ESBL)-phenotype was confirmed by Etest.

RESULTS

Rectal samples were obtained and analyzed from 208 patients with intra-abdominal surgical infections. Surgery was performed in 134 patients (65%). Cephalosporins were the most frequently used empirical antibiotic therapy. The highest rates of resistance among Enterobacteriaceae were detected for ampicillin (54%), tetracycline (26%), cefuroxime (26%) and trimethoprim-sulfamethoxazole (20%). The prevalence of decreased susceptibility (I + R) for the other antibiotics tested was for ciprofloxacin 20%, piperacillin-tazobactam 17%, cefotaxime 14%, ertapenem 12%, gentamicin 3% and imipenem 0%. ESBL-producing Enterobacteriaceae were found in samples from 10 patients (5%). Three patients had five E. coli isolates producing AmpC enzymes.

CONCLUSIONS

This study shows a high rate of resistance among Enterobacteriaceae against antibiotics which are commonly used in Sweden and should have implications for the future choice of antibiotics for surgical patients.

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.

Risk factors for multidrug-resistant bacteria in patients with post-operative peritonitis requiring intensive care

OBJECTIVES

This prospective non-interventional study investigated the risk factors for multidrug-resistant bacteria (MDRB) in patients with post-operative peritonitis (POP), to provide guidance for empirical antimicrobial therapy.

METHODS

All consecutive patients, >15 years old, admitted to a surgical intensive care unit (ICU) between September 2006 and January 2009 for a first episode of POP were included. Antibiotic susceptibilities of microorganisms recovered from blood cultures and peritoneal fluid were determined by disc diffusion. Amoxicillin/clavulanic acid, ticarcillin/clavulanic acid, piperacillin/tazobactam, cefotaxime, ceftazidime, cefepime, imipenem, gentamicin, amikacin and ciprofloxacin were tested against Gram-negative bacteria, and oxacillin, amoxicillin, vancomycin, gentamicin and erythromycin were tested against aerobic Gram-positive bacteria. Results were reported as susceptible or resistant.

RESULTS

MDRB were isolated from 20/115 (17%) patients. In univariate analysis, use of antimicrobial therapy during the 3 months prior to hospitalization and a long duration between hospital admission or first operation and relaparotomy were significantly associated with MDRB recovery. In multivariate analysis, only antimicrobial treatment in the 3 months preceding hospitalization and duration between first operation and relaparotomy were independent risk factors for MDRB [odds ratio (OR) = 5.80, 95% confidence interval (95% CI) = 1.99-16.91 and OR = 1.10, 95% CI = 1.02-1.19, respectively]. No MDRB were found when the delay between the first operation and relaparotomy was <5 days. POP severity, non-surgical and surgical complications, hospital and ICU length of stay, and mortality were similar in patients with and without MDRB.

CONCLUSIONS

Our results suggest that broad-spectrum antibiotics should be used in ICU patients with POP who have received antimicrobial therapy in the 3 months prior to hospitalization, or with >5 days between the first operation and relaparotomy.

Epidemiology, management, and prognosis of secondary non-postoperative peritonitis: a French prospective observational multicenter study

BACKGROUND

Despite improvements in treatment, secondary peritonitis still is associated with high morbidity and mortality rates. Better knowledge of real-life clinical practice might improve management.

METHODS

Prospective, observational study (January-June 2005) of 841 patients with non-postoperative secondary peritonitis.

RESULTS

Peritonitis originated in the colon (32% of patients), appendix (31%), stomach/duodenum (18%), small bowel (13%), or biliary tract (6%). Most patients (78%) presented with generalized peritonitis and 26% with severe peritonitis (Simplified Acute Physiology Score [SAPS] II score>38). Among the 841 patients, 27.3% underwent laparoscopy alone; 11% underwent repeat surgery, percutaneous drainage, or both. A SAPS II score>38 and the presence of Enterococcus spp. were predictive of abdominal and non-surgical infections (odds ratio [OR]=1.84; p=0.013 and OR=2.93; p<0.0001, respectively). A SAPS II score>38 also was predictive of death (OR=10.5; p<0.0001). The overall mortality rate was high (15%). Patients receiving inappropriate initial antimicrobial therapy had significantly higher morbidity and mortality rates than patients receiving appropriate therapy (44 vs. 30%; p=0.004 and 23% vs. 14%; p=0.015, respectively). The SAPS II score and rates of severe peritonitis, morbidity, and mortality were significantly lower in patients with appendiceal peritonitis.

CONCLUSIONS

Patients with non-postoperative peritonitis should be considered high risk and should receive appropriate initial therapy. The presence of Enterococcus spp. in peritoneal cultures significantly increased morbidity but not the mortality rate. Appendiceal peritonitis that was less severe and had a better prognosis than peritonitis originating in other sites should be considered a special case in future studies.

Cost-effectiveness evaluation of ertapenem versus piperacillin/tazobactam in the treatment of complicated intraabdominal infections accounting for antibiotic resistance

OBJECTIVE

To evaluate the cost-effectiveness of ertapenem versus piperacillin/tazobactam in the treatment of community-acquired complicated intraabdominal infections accounting for development of antibiotic resistance in the Dutch setting.

METHODS

A decision tree was developed to estimate cost-effectiveness of ertapenem versus piperacillin/tazobactam at different time points after introduction of treatment. Development of resistance was incorporated using a compartment model. Resistance was a function of the eradication rate of pathogens and antibiotic prescription. Model outcomes included quality-adjusted life years (QALYs), direct costs and cost per QALY saved. Microbiological eradication rate, clinical success, and costs were derived from literature. The analyses included pathogens with intrinsic or acquired resistance.

RESULTS

The model suggested overall savings of euro355 (95% uncertainty interval euro480; euro1205) per patient when abdominal infections are treated with ertapenem instead of piperacillin/tazobactam. Probabilistic sensitivity analysis found a 94% probability of the incremental cost per QALY saved being within the generally accepted threshold for cost-effectiveness (euro20,000). After 5 years, it is expected that antibiotic resistance with piperacillin/tazobactam has increased with a greater rate compared to ertapenem, and cost-savings with ertapenem are expected to increase to euro672 (euro-232; euro1617). Ertapenem will, in addition, result in greater success rates and in QALY savings (0.17; 0.07-0.30). Alternative scenarios, with lower levels of initial resistance confirm the cost savings with ertapenem.

CONCLUSION

Given the underlying assumptions and data used, this evaluation demonstrated that ertapenem is a cost saving and possibly an economically dominant therapy over piperacillin/tazobactam for the treatment of community-acquired intraabdominal infections in The Netherlands.

A prospective, double-blind, multicenter, randomized trial comparing ertapenem 3 vs >or=5 days in community-acquired intraabdominal infection

Severe secondary peritonitis is diagnosed in only 20-30% of all patients, but studies to date have persisted in using a standard fixed duration of antibiotic therapy. This prospective, double-blind, multicenter, randomized clinical study compared the clinical and bacteriological efficacy and tolerability of ertapenem (1 g/day) 3 days (group I) vs >or=5 days (group II) in 111 patients with localized peritonitis (appendicitis vs non-appendicitis) of mild to moderate severity, requiring surgical intervention. In evaluable patients, the clinical response as primary efficacy outcome were assessed at the test-of-cure 2 and 4 weeks after discontinuation of antibacterial therapy. Ninety patients were evaluable. In groups I and II, 92.9 and 89.6% of patients were cured, respectively; 95.3% in group I and 93.7% in group II showed eradication. These differences were not statistically significant. The most frequent bacteria recovered were Escherichia coli and Bacteroides fragilis. A wound infection developed in seven patients (7.7%) and an intraabdominal infection in one patient (1.1%). There was a low frequency of drug-related clinical or laboratory adverse effects in both groups. Our study demonstrated that, in patients with localized community-acquired intraabdominal infection, a 3-day course of ertapenem had the same clinical and bacteriological efficacy as a standard duration.

Antimicrobial treatment for intra-abdominal infections

Treatment of patients with complicated intra-abdominal infections involves antimicrobial therapy, generally in conjunction with an interventional procedure to control the source of the infection. Antimicrobial regimens effective against common gram-negative and anaerobic enteric pathogens are the mainstay of therapy. For patients with community-acquired intra-abdominal infections, efficacy is comparable among the various single-agent or combination regimens recommended for therapy. Narrower-spectrum antimicrobial agents with a low potential for iatrogenic complications are appropriate for these patients. Patients with nosocomially-acquired, intra-abdominal infections are more likely to harbor resistant pathogens. Inadequate empiric antimicrobial therapy is associated with treatment failure and death. Therefore, broader spectrum antimicrobial regimens are recommended for these patients. In addition to coverage of more resistant gram-negative bacilli and anaerobes, use of agents effective against enterococci, resistant staphylococci and Candida should be considered. De-escalation of an initially broad antimicrobial regimen should be undertaken once definitive culture results are available.

Consequences of inappropriate initial empiric parenteral antibiotic therapy among patients with community-acquired intra-abdominal infections in Spain

To assess the association between inappropriate antibiotic therapy and clinical outcomes for complicated community-acquired intra-abdominal infections in Spain, patient records from October 1998 to August 2002 in 24 hospitals were reviewed. Initial empiric therapy was classified appropriate if all isolates were sensitive to at least 1 of the antibiotics administered. Multivariate analyses were performed to assess associations between appropriateness of therapy and patient outcomes. Healthcare resource use was measured as hospital length of stay (LOS) and d on intravenous antibiotic therapy. A total of 425 patients were included. Of these, 387 (91%) received appropriate initial empiric therapy. Patients on inappropriate therapy were less likely to have clinical success (79% vs 26%, p<0.001), more likely to require additional antibiotic therapy (40% vs 7%, p<0.01) and more likely to be re-hospitalized within 30 d of discharge (18% vs 3%, p<0.01). Multivariate analyses also showed that inappropriate therapy was associated with an almost 16% increase in LOS (p<0.05) and 26% in d of intravenous antibiotic therapy compared with appropriate therapy (p<0.05). Inappropriate initial antibiotic therapy was associated with a significantly higher proportion of unsuccessful patient outcomes (including death, re-operation, re-hospitalization or additional parental antibiotic therapies), increased length of stay and length on therapy.

Factors associated with multidrug-resistant bacteria in secondary peritonitis: impact on antibiotic therapy

Secondary peritonitis includes community-acquired and nosocomial peritonitis. These intra-abdominal infections have a common pathogenesis but some microbiological differences, particularly with respect to the type of bacteria recovered and the level of antimicrobial susceptibility. This report describes a prospective observational study of 93 consecutive patients with secondary peritonitis during an 11-month period. Community-acquired peritonitis accounted for 44 cases and nosocomial peritonitis for 49 cases (post-operative in 35 cases). Fifteen multidrug-resistant (MDR) bacteria were recovered from 14 patients. In univariate analysis, the presence of MDR bacteria was associated significantly with pre-operative and total hospital lengths of stay, previous use of antimicrobial therapy, and post-operative antimicrobial therapy duration and modifications. A 5-day cut-off in length of hospital stay had the best specificity (58%) and sensitivity (93%) for predicting whether MDR bacteria were present. In multivariate analysis, only a composite variable associating pre-operative hospital length of stay and previous use of antimicrobial therapy was a significant independent risk-factor for infection with MDR bacteria. In conclusion, knowledge of these two factors may provide a more rational basis for selecting initial antimicrobial therapy for patients with secondary peritonitis.

The Surgical Infection Society guidelines on antimicrobial therapy for intra-abdominal infections: an executive summary

The Surgical Infection Society last published guidelines on antimicrobial therapy for intra-abdominal infections in 1992 (Bohnen JMA, et al., Arch Surg 1992;127:83-89). Since then, an appreciable body of literature has been published on this subject. Therefore, the Therapeutics Agents Committee of the Society undertook an effort to update the previous guidelines, primarily using data published over the past decade. An additional goal of the Committee was to characterize its recommendations according to contemporary principles of evidence-based medicine. To develop these guidelines, the Committee carried out a systematic search for all English language articles published between 1990 and 2000 related to antimicrobial therapy for intra-abdominal infections. This literature was reviewed individually and collectively by the Committee, and categorized according to the type of study and its quality. Additional articles published prior to 1990 were also utilized when necessary. By a process of iterative consensus, the Committee developed provisional guidelines for antimicrobial therapy for intra-abdominal infections based on this evidence. Following extensive review by members of the Society, these guidelines were approved for publication in final form by the Council of the Surgical Infection Society. This executive summary delineates the Society's current recommendations for antimicrobial therapy of patients with intra-abdominal infections. Topics discussed include the selection of patients needing therapeutic antimicrobials, duration of antimicrobial therapy, acceptable antimicrobial regimens, and identification and treatment of higher-risk patients. Guidelines for patient selection and specific antimicrobial regimens were based on relatively good evidence, but those regarding optimal duration of therapy and treatment of higher-risk patients relied mostly on expert opinion, since there was a paucity of high-quality studies on those issues. Relevant areas for future investigation include the safety, convenience, and cost-effectiveness of available antimicrobial regimens for lower-risk patients, and better means for identifying and treating higher-risk patients with intra-abdominal infections.

The Surgical Infection Society guidelines on antimicrobial therapy for intra-abdominal infections: evidence for the recommendations

Revised guidelines for the use of antimicrobial therapy in patients with intra-abdominal infections were recently developed by the Therapeutic Agents Committee of the Surgical Infection Society (Mazuski et al., Surg Infect 2002;3:161-173). These were based, insofar as possible, on evidence published over the past decade. The objective of this document is to describe the process by which the Committee identified and reviewed the published literature utilized to develop the recommendations and to summarize the results of those reviews. English-language articles published between 1990 and 2000 related to antimicrobial therapy for intra-abdominal infections were identified by a systematic MEDLINE search and an examination of references included in recent review articles. If current literature with regard to a specific issue was lacking, relevant articles published prior to 1990 were identified. All prospective randomized controlled trials, as well as other articles selected by the Committee, were evaluated individually and collectively. Data with regard to patient numbers, types of infections, and results of interventions were abstracted. Studies were categorized according to their design, and all included trials were graded according to quality. On the basis of this evidence, the Committee formulated recommendations for antimicrobial therapy for intra-abdominal infections and graded those recommendations. After receiving comments from invited reviewers and the general membership of the Society, the guidelines were finalized and submitted to the Council of the Surgical Infection Society for approval. The final recommendations related to the selection of patients needing therapeutic antimicrobials, acceptable antimicrobial regimens, duration of antimicrobial use, and the identification and treatment of higher-risk patients. Although numerous publications pertaining to these topics were identified, but nearly all of the prospective randomized controlled trials represented comparisons of different antimicrobial regimens for the treatment of intra-abdominal infections. A few prospective trials evaluated the need for therapeutic antimicrobial therapy in patients with peritoneal contamination following abdominal trauma. The quality of these prospective trials was highly variable. Many did not limit enrollment to patients with complicated intra-abdominal infections, lacked blinding of treatment assignment, did not provide a complete description of the criteria used to determine therapeutic success or failure, failed to identify the reasons why patients were excluded from analysis, or did not include an intention-to-treat analysis. For many issues, no prospective randomized controlled trials were encountered, and guidelines had to be formulated using evidence from studies with historical controls or uncontrolled data, or on the basis of expert opinion

Microdialysis study of imipenem distribution in the intraperitoneal fluid of rats with or without experimental peritonitis

The purpose of this study was to extend the use of microdialysis to the investigation of antibiotic distribution into the intraperitoneal fluid of rats with or without peritonitis. Microdialysis probes were inserted into the jugular vein and peritoneal cavity of control rats or rats with intra-abdominal sepsis (n = 8 in each group) induced by cecal ligation and punctures. Imipenem (IPM) probe recoveries were determined in each rat by retrodialysis by drug. IPM was infused intravenously at a dose of 30 mg . kg(-1) over 30 min, microdialysis samples were collected for 120 min, and IPM concentrations were determined by high-performance liquid chromatography. Intraperitoneal infection had no statistically significant effect on IPM clearance (11.9 +/- 2.3 ml.min(-1).kg(-1) in control rats versus 10.9 +/- 2.1 ml.min(-1).kg(-1) in rats with peritonitis) or the volume of distribution (296 +/- 47 ml.kg(-1) in control rats versus 310 +/- 49 ml.kg(-1) in rats with peritonitis). IPM concentration profiles in intraperitoneal fluid and blood were virtually superimposed in control rats, whereas in infected animals, the mean intraperitoneal IPM concentrations were apparently slightly lower than corresponding blood levels. However, the areas under the concentration-versus-time curve estimated in intraperitoneal fluid and blood were not significantly different in both groups, with the corresponding ratios close to unity (1.01 +/- 0.19 and 0.89 +/- 0.28 in control rats and rats with peritonitis, respectively). In conclusion, IPM distribution in intraperitoneal fluid is rapid and complete both in control rats and in rats with peritonitis.

Importance of appropriateness of empiric antibiotic therapy on clinical outcomes in intra-abdominal infections

Objectives:The objective of this study is to describe the frequency of inappropriate empirical antibiotic therapy in secondary intra-abdominal infection and to identify the possible relationship between inappropriateness and some clinical outcomes.

Methods:A retrospective descriptive multicenter study was conducted using hospital secondary databases developed at two university hospitals located in northeast Spain. Participants were patients 18 years of age or older who were diagnosed with community-acquired intra-abdominal infections between January 1, 1998, and December 31, 2000, identified through computerized patient records using ICD-9 codes. Appropriateness of empirical treatment was defined according to the recommendations of the literature. The clinical outcome of each patient was classified as one of the following: (i) resolved with initial therapy, (ii) required second-line antibiotics, (iii) required re-operation, or (iv) in-hospital death. The Fisher's exact test or the Chi-squared test for categorical variables and thet-test or Mann–Whitney test for continuous variables were used for comparing groups. Conditional logistic and linear regression analyses were also applied.

Results:Of 376 cases, 51 cases (13.6 percent, 95 percent confidence interval, 10–17 percent) received inappropriate empirical antibiotic therapy according to the scientific literature. Inappropriate initial empirical treatment was significantly associated with the need for a second line of antibiotics (p<.001), although not with re-operation, mortality, or length of hospitalization.

Conclusions:Approximately 14 percent of the patients received inappropriate empirical antibiotic treatment. Worse clinical outcomes consistently were observed in the group of patients receiving inappropriate empirical treatment. The appropriateness of antibiotic treatment for a given infection, in light of the availability of clearly defined clinical guidelines is an easily evaluated aspect of the quality of care.

[Therapeutic management of peritonitis]

Antibiotherapy is a fundamental for the treatment of peritonitis. It may be used before surgery or as a complementary treatment after. Experimental models have demonstrated that infections are both aerobic and anaerobic. During the first stage, septicemic with a high death rate, the infection is due to enterobacteria, mostly Escherichia coli. Between D5 and D7 in surviving animals, there is a second stage with abscesses due to anaerobic bacteria, mostly Bacteroides fragilis. The antibiotic treatment must include these two types of bacteria in its spectrum. The role of Enterococcus faecalis is not clearly defined, but this bacterium must be taken into account in case of organ failure or associated septic shock. Treatment options for secondary peritonitis may be, according to severity, cefoxitin, an Augmentin + gentamycin combination, Tazocillin, or ertapenem. The reference treatment for nosocomial or tertiary peritonitis is the imipenem + amikacin combination. An antifungal treatment (fluconazole) is usually necessary, at least until the results of peritoneal fluid culture are available. The duration of treatment is quite variable, ranging from 48 h in less severe forms to 14 days.

Empiric Treatment of Nosocomial Intra-Abdominal Infections: A Focus on the Carbapenems

BACKGROUND

Serious nosocomial intra-abdominal infections are associated with high morbidity and mortality and represent a substantial drain on healthcare resources. Effective management of this type of infection requires the early use of appropriate, broad-spectrum empiric antimicrobial therapy. The consequences of delayed or inappropriate antimicrobial treatment can be severe-leading to an increased risk of death, re-operation, or prolonged hospitalization. Therefore, it is necessary to begin treatment as soon as possible with the most appropriate regimen, in terms of spectrum, timing, and duration.

METHODS

Review of pertinent English-language literature.

RESULTS

Serious nosocomial intra-abdominal infections require broad-spectrum coverage because of the wide range of possible pathogens, which include difficult-to-treat organisms such as Pseudomonas aeruginosa and Bacteroides spp., and resistant strains of Klebsiella spp., Escherichia coli, and methicillin-resistant Staphylococcus aureus acquired from the hospital flora. The early use of appropriate, broad-spectrum empiric antimicrobial therapy for treating high-risk patients with intra-abdominal infections is considered, and appropriate use of the carbapenems, meropenem, and imipenem/cilastatin, is described.

CONCLUSION

The carbapenems meropenem and imipenem/cilastatin have a spectrum of antimicrobial activity that covers the majority of expected pathogens, including anaerobes, as well as difficult-to-treat and resistant gram-negative strains. Early and appropriate use can reduce mortality and morbidity. Data from published clinical trials support the clinical effectiveness of these two carbapenems in intra-abdominal infections.

Antibiotic regimens for secondary peritonitis of gastrointestinal origin in adults

BACKGROUND

Secondary peritonitis is associated with a high mortality rate and if not treated successfully leads to development of abscesses, severe sepsis and multi-organ failure. Source control and adjunctive antibiotics are the mainstay of treatment. However, no conclusive evidence suggest that one antibiotic regimen is better than any other but at the same time have a lower toxicity.

OBJECTIVES

To ascertain the efficacy and adverse effects of different antibiotic regimens in treating intra-abdominal infections in adults. Outcomes were divided into primary (clinical success and effectiveness in reducing mortality) and secondary (microbiological success, preventing wound infection, intra-abdominal abscess, clinical sepsis, remote infection, superinfection, adverse reactions, duration of treatment required, effectiveness in reducing hospitalised stay, and time to defervescence).

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library, Issue 4, 2004), MEDLINE (from 1966 to November 2004), EMBASE (from 1980 to November 2004) and Cochrane Colorectal Cancer Group specialised register SR-COLOCA. Bibliographies of identified studies were screened for further relevant trials.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different antibiotic regimens in the treatment of secondary peritonitis in adults were selected. Trials reporting gynaecological or traumatic peritonitis were excluded from this review. Ambiguity regarding suitability of trials were discussed among the review team.

DATA COLLECTION AND ANALYSIS

Six reviewers independently assessed trial quality and extracted data. Data collection was standardised using data collection form to ensure uniformity among reviewers. Statistical analyses were performed using the random effects model and the results expressed as odds ratio for dichotomous outcomes, or weight mean difference for continuous data with 95% confidence intervals.

MAIN RESULTS

Fourty studies with 5094 patients met the inclusion criteria. Sixteen different comparative antibiotic regimens were reported. All antibiotics showed equivocal comparability in terms of clinical success. Mortality did not differ between the regimens. Despite the potential high toxicity profile of regimens using aminoglycosides, this was not demonstrated in this review. The reason for this could be the inherent bias within clinical trials in the form of patient selection and stringency in monitoring drug levels.

AUTHORS' CONCLUSIONS

No specific recommendations can be made for the first line treatment of secondary peritonitis in adults with antibiotics, as all regimens showed equivocal efficacy. Other factors such as local guidelines and preferences, ease of administration, costs and availability must therefore be taken into consideration in deciding the antibiotic regimen of choice. Future trials should attempt to stratify patients and perform intention-to-treat analysis to allow better external validity.

Ertapenem versus ceftriaxone and metronidazole as treatment for complicated intra-abdominal infections

BACKGROUND

Prompt surgical intervention supplemented by appropriate antimicrobial therapy is usually required for successful treatment of complicated intra-abdominal infections. The objective of this study was to further evaluate the efficacy and safety of ertapenem relative to ceftriaxone/metronidazole as treatment for complicated intra-abdominal infections.

METHODS

Adult patients with intra-abdominal infections requiring surgery were eligible for this open-label randomized trial comparing ertapenem 1 g daily with ceftriaxone 2 g daily plus metronidazole 30 mg/kg/day. The primary efficacy outcome was the clinical response rate in clinically and microbiologically evaluable participants at the test-of-cure (TOC) visit 2 weeks after discontinuation of therapy. All treated patients were included in the safety analysis.

RESULTS

Participant demographics, disease characteristics, and duration of therapy in both treatment groups were generally similar. Escherichia coli was the most commonly isolated baseline pathogen, recovered in 52% of cases in each treatment group. Favorable clinical responses were achieved at TOC in 143 (96.6%) of 148 ertapenem recipients and in 146 (96.7%) of 151 ceftriaxone/metronidazole recipients. The frequencies of drug-related adverse events, most commonly nausea, diarrhea, vomiting, and elevated platelet count, were generally comparable in both treatment arms. Four ertapenem recipients (1.8%) and one ceftriaxone/metronidazole recipient (0.4%) experienced serious drug-related adverse events.

CONCLUSIONS

In this study, ertapenem and ceftriaxone/metronidazole were comparably effective treatments for adult patients with complicated intra-abdominal infections.

Intra-abdominal infections

Intra-abdominal infections in the hospitalized patient differ from those arising in the community in their clinical presentation, sites of involvement, and characteristic microbiology. They are also associated with greater morbidity and mortality. New onset organ dysfunction, more than acute abdominal pain and tenderness, is the predominant clinical manifestation. Successful management depends on aggressive resuscitation and hemodynamic support, administration of adequate antimicrobial therapy, and the timely use of source control measures appropriate to the clinical situation.

Clinical and therapeutic features of nonpostoperative nosocomial intra-abdominal infections

OBJECTIVE

To compare the clinical, microbiological, and therapeutic features of nonpostoperative nosocomial intra-abdominal infections (non-PostopNAI) with community-acquired intra-abdominal infections (CAI).

SUMMARY BACKGROUND DATA

Prospective (June 2000 through January 2001) consecutive case series analysis of patients operated for secondary nonpostoperative intra-abdominal infections collected in 176 study centers (surgical wards and intensive care units).

PATIENTS AND METHODS

Clinical, microbiological, and therapeutic characteristics of CAI and non-PostopNAI infections were collected. Management of antibiotic therapy was decided by the attending physician. The efficacy of treatment was evaluated over a 30-day period after the index episode.

RESULTS

Evaluatable observations (n = 1008) were collected (761 CAI and 247 non-PostopNAI), including 285 intensive care unit patients. When compared with CAI patients, non-PostopNAI patients presented an increased interval between admission to the surgical ward and operation (1.3 +/- 1.5 vs. 0.5 +/- 0.7 days in CAI patients; P < 0.001), increased proportions of underlying diseases, a more severe clinical condition as assessed by increased proportions of hospitalization in the intensive care unit (48% vs. 22% in CAI patients, P < 0.001) and a higher SAPS II score (34 +/- 15 vs. 24 +/- 14, P < 0.001). In non-PostopNAI patients, increased proportions of therapeutic failure (15% vs. 7% in CAI patients, P < 0.01) and of fatalities (12% vs. 4% in CAI patients, P < 0.001) were observed.

CONCLUSIONS

Delayed diagnosis and increased severity are the main characteristics of non-PostopNAI infections. Microbiological features are quite similar in CAI and non-PostopNAI infections, suggesting that antibiotic therapy recommended for CAI infections could be applied to non-PostopNAI patients. Characteristics of non-PostopNAI patients should lead to identify them as a specific entity in clinical trials.

Nosocomial Infections Adversely Affect the Outcomes of Patients with Serious Intraabdominal Infections

BACKGROUND

Patients with serious intraabdominal infections (IAI) who subsequently acquire nosocomial infections (NI) have been shown to have adverse outcomes. We evaluated factors that put patients at risk for developing NI and examined the effect of the NI on outcomes.

METHODS

This study was a retrospective review of NI among 168 patients diagnosed with IAI over a seven-year period.

RESULTS

Sixty-six patients (39.3%) developed 98 NI (23 urinary tract, 20 surgical site, 19 pneumonia, 14 bloodstream, 12 recurrent peritonitis, seven intravascular catheter-related, and three enteric). There were 35 males and 31 females. Patients with NI were older (56.0 +/- 18.3 vs. 47.0 +/- 15.6 years, p = 0.001), had a higher admission APACHE II score (10.7 +/- 6.1 vs. 7.5 +/- 5.1 points, p = 0.001), and more often had concomitant medical diagnoses (27.3% vs. 12.7%, OR = 2.57, 95% CI: 1.159-5.69, p = 0.018) than those who did not develop infection. Antimicrobial resistance among the IAI was higher in the NI group (19.7 vs. 5.9%, OR = 3.93, 95% CI: 1.41-10.93, p = 0.006). Patients who developed NI had an increased mortality rate (27.0% vs. 4.0%, OR = 8.87, 95% CI: 2.82-27.86, p < or = 0.0001), longer hospital stay (24.7 +/- 19.5 vs. 11.7 +/- 8.1 days, p < or = 0.0001), required more days of intravenous antibiotics (11.5 +/- 8.0 vs. 7.6 +/- 4.4 days, p < or = 0.0001), and were more likely to be admitted to an intensive care unit (54.5% vs. 25.5%, OR = 3.51, 95% CI: 1.82-6.77, p < or = 0.0001). Multivariate analysis demonstrated that antimicrobial resistance and an APACHE II score of > or = 10 independently predicted the development of a nosocomial infection. Age >/= 50 years, APACHE II score > or = 10, or the presence of a NI independently predicted death.

CONCLUSIONS

The development of NI following treatment of an IAI significantly affects mortality, hospital length of stay, and treatment. Early recognition and treatment of these infections, combined with strategies to prevent NI, may be important to improve outcomes in this patient population.

Current concepts in peritonitis

Peritonitis is a serious and common infection. Its pathogenesis and microbiology have been well defined. Such risk factors as age, site of infection, physiologic response of the patient, presence of organ dysfunction, and malnutrition may influence the outcome of this disease process. The presence of antibiotic-resistant organisms and delays in operative intervention are also associated with treatment failure and higher mortality. Surgeons have the greatest impact on this disease in their ability to control the source of infection and to administer proper antimicrobial therapy.

Preventing antimicrobial-resistant bacterial infections in surgical patients

BACKGROUND

The Centers for Disease Control and Prevention (CDC) has identified the control of antimicrobial resistance as an important effort to reduce the morbidity and mortality associated with health care. Methods to prevent these infections in surgical patients have rarely been addressed specifically.

METHODS

The peer-reviewed literature and published guidelines were examined to identify proven or suggested techniques for controlling antimicrobial resistance that would be particularly relevant to surgeons and the surgical patient population.

RESULTS

A multi-step approach to the prevention of antimicrobial-resistant infections in surgical patients was developed. This program consists of four major strategies: Infection prevention, effective diagnosis and treatment of infection, optimal antibiotic utilization, and the prevention of transmission.

CONCLUSION

The control of antimicrobial resistance in bacteria is an important objective for all physicians, including surgeons. An approach to attain this goal in surgical populations is outlined. Further research will be needed to determine the value of these practices and to develop newer, even more effective interventions.

The consequences of suppression of anaerobic bacteria

Anaerobic bacteria such as Bacteroides fragilis, Peptostreptococcus species, and Fusobacterium species, when accompanied by aerobic bacteria or in the presence of dead tissue, can cause severe infections. This article discusses the most common type of anaerobic infection, i.e., infection after colonic contamination of the abdominal cavity and soft tissues. Colonic anaerobes rarely cause infections as solitary pathogens. Mixed infections of aerobes and anaerobes are treated by source control, surgical drainage and debridement, and combination antibiotic therapy. Antimicrobial treatment should cover both anaerobes and aerobes; treatment of mixed infections with anti-anaerobic agents alone is likely to result in abscess formation. Recent trends toward cost cutting and the advent of antibiotics with good coverage of both aerobes and relevant pathogenic anaerobes have led to increased single-agent therapy with cefoxitin, cefotetan, ampicillin/sulbactam, imipenem/cilastatin, ticarcillin/clavulanate, trovafloxacin/alatrofloxacin, and piperacillin/tazobactam. In the past 15 years, research has begun to focus on the gut barrier, particularly on the beneficial effects of anaerobic microflora. Directing antibiotic therapy against the anaerobe when it is involved in clinical infection is important; however, the negative consequences of anti-anaerobic antibiotic therapy on the beneficial effects of normal distal gut colonization must also be considered.