Antibiotic treatment for surgical peritonitis

Fifty years devoted to anaerobes: historical, lessons, and highlights

Renew interest and enthusiasm for anaerobes stem from both technological improvements (culture media, production of an adequate anaerobic atmosphere, identification methods) and greater awareness on the part of clinicians. Anaerobic infections were historically treated empirically, targeting the species known to be involved in each type of infection. Prevotella, fusobacteria, and Gram-positive cocci (GPAC) were considered responsible for infections above the diaphragm whereas for intra-abdominal infections, Bacteroides of the fragilis group (BFG), GPAC and clostridia were predominantly implicated. The antibiotic susceptibility of anaerobes was only taken into consideration by the clinician in the event of treatment failure or when faced with infections by multidrug-resistant bacteria (MDR). The evolution of antibiotic resistance together with clinical failures due to the absence of detection of hetero-resistant clones has resulted in a greater need for accessible antibiotic susceptibility testing (AST) and disc diffusion method. Improved isolation and identification of anaerobes, along with the availability of accessible and robust methods for performing AST, will ensure that treatment, whether empirical or guided by an antibiogram, will lead to better outcomes for anaerobic infections.

Impact of empiric antibiotic therapy on the clinical outcome of acute calculous cholecystitis

PURPOSE

Although mortality and morbidity of severe acute calculous cholecystitis (ACC) are still a matter of concern, the impact of inadequate empirical antibiotic therapy has been poorly studied as a risk factor. The objective was to assess the impact of the adequacy of empirical antibiotic therapy on complication and mortality rates in ACC.

METHODS

This observational retrospective cohort chart-based single-center study was conducted between 2012 and 2016. A total of 963 consecutive patients were included, and pure ACC was selected. General, clinical, postoperative, and microbiological variables were collected, and risk factors and consequences of inadequate treatment were analyzed.

RESULTS

Bile, blood, and/or exudate cultures were obtained in 76.3% of patients, more often in old, male, and severely ill patients (P < 0.001). Patients who were cultured had a higher overall rate of postoperative complications (47.4% vs. 29.7%; P < 0.001), as well as of severe complications (11.6% vs. 4.7%; P = 0.008). Patients with positive cultures had more overall complications (54.8% vs. 39.6%; P = 0.001), more severe complications (16.3% vs. 6.7%; P = 0.001), and higher mortality rates (6% vs. 1.9%; P = 0.012). Patients who received inadequate empirical antibiotic therapy had a fourfold higher mortality rate than those receiving adequate therapy (n = 283; 12.8% vs. 3.4%; P = 0.003). This association was especially marked in severe ACC TG-III patients (n = 132; 18.2 vs. 5.1%; P = 0.018) and remained a predictor of mortality in a binary logistic regression (OR 4.4; 95% CI 1.3-15.3).

CONCLUSION

Patients with positive cultures developed more complications and faced higher mortality. Adequate empirical antibiotic therapy appears to be of paramount importance in ACC, particularly in severely ill patients.

Outcomes of Beta-Lactam Allergic and Non-Beta-Lactam Allergic Patients with Intra-Abdominal Infection: A Case-Control Study

Background: In the case of intra-abdominal infections (IAI) in beta-lactam (BL) allergic patients, empiric antimicrobial therapy without BL is recommended; however, data regarding the outcome with alternative regimens are scarce. This study aimed to compare the outcomes of BL allergic (BLA) patients with IAI to those who were non-BLA (NBLA). Method: We conducted a case−control study in a French teaching hospital, between 1 January 2016 and 31 August 2021. BLA patients with IAI treated with fluoroquinolone or aztreonam and metronidazole were matched with controls treated with BL, on age, sex, disease severity, IAI localization, and healthcare-associated infection (HAI) status. We compared rates of therapeutic failures, adverse events, and HAI, and then assessed factors associated with therapeutic failure using a logistic regression model. Results: The therapeutic failure rate was 14% (p > 0.99) in both groups of 43 patients, and there was no significant difference in the adverse events rate (p > 0.99) and HAI rate (p = 0.154). Factors independently associated with therapeutic failure were higher BMI (OR 1.16; 95%CI [1.00−1.36]; p = 0.041), longer hospital length of stay (OR 1,20; 95%CI [1.08−1.41]; p = 0.006), and inadequate empiric antimicrobial therapy (OR 11.71; 95%CI [1.43−132.46]; p = 0.025). Conclusion: The outcomes of BLA patients with IAI treated without BL were the same as those for NBLA patients treated with BL.

Effectiveness of Five Antibiotic Regimens for the Treatment of Intra-Abdominal Infection in Bogotá

Background: Intra-abdominal infection (IAI) results in prolonged in-hospital length-of-stay, critical care unit requirements, and multiple surgical procedures. Several antimicrobial agents are available for treatment of IAI. In Colombia, there are no data on the comparative effectiveness of the different regimens used. Patients and Methods: A multicenter retrospective cohort study was completed in four third-level hospitals by comparing treatment effectiveness of five different antibiotic protocols (ampicillin-sulbactam, clindamycin-amikacin, piperacillin-tazobactam, amikacin-metronidazole, and cefuroxime-metronidazole) in patients with a diagnosis of IAI. Analysis was based on a composed outcome of therapeutic failure (change of antibiotic because of no clinical improvement, requirement of surgical re-intervention, post-operative infection, change of antibiotic because of antimicrobial resistance, and in-hospital mortality). Association of each antibiotic protocol to therapeutic failure was assessed through logistic regression analysis. Results: Five hundred ninety-three individuals were included. Two hundred twenty-nine were prescribed ampicillin-sulbactam; 170, clindamycin-amikacin; 77, amikacin-metronidazole; 83, piperacillin-tazobactam; and 34, cefuroxime-metronidazole. Therapeutic failure rate was 22%. Multivariable analysis showed none of the evaluated antibiotic protocols had an association with the primary outcome. Variables having an association for higher risk were age >70 years old (odds ratio [OR], 2.08; 95% confidence interval [CI], 1.04-4.18); complicated IAI (OR, 3.36; 95% CI, 1.4-8.07); and World Society of Emergency Surgery (WSES) Sepsis Severity Score (OR, 1.31; 95% CI, 1.18-1.45). Adequate source control (OR, 0.16; 95% CI, 0.05-0.45) and hospitalization at Health Center 2 (OR, 0.30; 95% CI, 0.14-0.63) were identified as protective factors. Conclusions: There are no differences between the rate of therapeutic failure among the different antibiotic protocols evaluated. This outcome depends heavily on risk factors related to disease severity when surgical intervention occurs.

Bacterial and Antibiotic Sensitivity Pattern in Secondary Peritonitis

Background

Peritonitis is inflammation of the peritoneum usually as a result of a localized or generalized infection. Secondary peritonitis which is the most common type follows an infective process in a visceral organ. The role of peritoneal cultures and use of antibiotics effective against culture results remain controversial.

Objectives

This study was conducted to determine the bacterial and antibiotic sensitivity pattern in patients with secondary peritonitis. It also compared the use of empirical antibiotics and culture-sensitive antibiotics with outcomes of patients with secondary peritonitis.

Materials and Methods

A prospective randomized clinical study was conducted. Five millilitres of peritoneal fluid was sampled intra-operatively, and microscopy, culture, and sensitivity testing was performed in patients with secondary peritonitis. The patients, randomized into two groups, had antibiotics administered for 7 days. The first group had empirical antibiotics throughout (Ceftriaxone + Metronidazole), whereas the second group had empirical antibiotics (Ceftriaxone + Metronidazole) for the first 2 days and antibiotics according to the sensitivity report for the remaining 5 days. The post-hoc analysis was also done on a third group, who, even though were randomized to either groups, had no growth on culture of peritoneal fluid.

Results

The commonest pathogens identified from the peritoneal culture of the participants were Escherichia coli, Klebsiella pneumonia, Anaerococcus group, and Bacteroides fragilis. Complications including mortality were significantly higher in those who received empirical antibiotics than those who received culture-sensitive antibiotics.

Conclusion

The outcome of antibiotics administration in patients with secondary peritonitis with a positive culture was better in those who received culture-sensitive antibiotics than those who received empirical antibiotics.

Risk factors and mortality associated with multidrug-resistant gram-negative bacterial infection in adult patients with abdominal surgery

BACKGROUND

Multidrug-resistant (MDR) gram-negative bacterial (GNB) infections remain a significant cause of morbidity and mortality among surgical patients. The objective of our study was to recognize the risk factors for MDR GNB infection in patients with abdominal surgery and determine the predictors independently associated with death.

METHODS

From 2010 to 2017, a retrospective cohort study was conducted among patients with abdominal surgery admitted in surgical intensive care unit (ICU). Patients with GNB infections were included for analyses.

RESULTS

A total of 364 patients with abdominal surgery experienced GNB infections, among them, 117 (32.1%) were MDR GNB infection. Of 133 MDR GNB isolates, the most frequent isolate was Escherichia coli (45.1%). Patients with MDR GNB infection had significantly longer ventilator days and hospital stay, as well as higher 30-day and in-hospital mortality compared to non-MDR GNB patients. Multivariable analysis showed longer length of pre-ICU stay, surgical re-exploration, receipt of group 2 carbapenems (e.g. imipenem, meropenem and doripenem) and fluoroquinolones, and higher total bilirubin were independent risk factors for the acquisition of MDR GNB infection. Predictors for 30-day mortality among patients with MDR GNB infection were chronic kidney disease, receipt of group 2 carbapenems and inappropriate empirical antimicrobial therapy.

CONCLUSIONS

This study provides important information about the risk factors for subsequent MDR GNB infection and 30-day mortality among the patients with abdominal surgery.

Correlation between antibiotic resistance and clinical outcome of anaerobic infections; mini-review

In anaerobic infections, the relationship between clinical failure and antibiotic resistance is difficult to demonstrate, especially in mixed anaerobic-aerobic infections. Single isolates of anaerobes in cases of bacteraemia revealed that treatment failures were due to inappropriate therapy. We review here cases, where the empiric treatment was unsuccessful due to resistance of anaerobic bacteria to the administered agents and where the change of the antibiotic allowed the patients to be cured. Many therapeutic failures could be linked to the lack of timely detection of resistance, including heteroresistance of the anaerobes. Disk diffusion or Etest methodology may be suitable, at least for rapidly growing anaerobes, to detect both resistance and heteroresistance to antibiotics widely used for empirical therapy.

Appropriateness of Empirical Fluoroquinolones Therapy in Patients Infected with Escherichia coli, Klebsiella pneumoniae, or Pseudomonas aeruginosa: The Importance of the CLSI Breakpoints Revision

Purpose

Empirical antibiotic therapy should follow the local bacterial susceptibility, and the breakpoints revisions of the antimicrobial susceptibility testing can reflect the changes in the antimicrobial susceptibility of bacteria. This study aimed to analyze whether the changes in the antimicrobial susceptibility to antibiotics caused by the breakpoint revision will affect the empirical antibiotic therapy and its appropriateness.

Patients and Methods

A retrospective study was conducted among 831 hospitalized patients infected by Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa from April 10, 2018, to April 11, 2020. We evaluated the appropriateness of empirical therapy based on the antimicrobial susceptibility testing results. The rate of empirical use and appropriateness of fluoroquinolones was calculated, and logistic regression was used to analyze influencing factors of empirical use of fluoroquinolones.

Results

The susceptibility rate of the three bacteria to levofloxacin (50.78% vs 32.06%) and ciprofloxacin (48.45% vs 21.90%) was decreased (P<0.001), while the resistance rate to levofloxacin (45.74% vs 58.73%) and ciprofloxacin (46.90% vs 66.67%) was increased (P<0.001) after the breakpoints revision. The empirical usage rate of fluoroquinolones in patients infected with Escherichia coli, Klebsiella pneumoniae, or Pseudomonas aeruginosa was 20.94%, which was influenced by the breakpoint revision (P=0.022), age (P=0.007), and the department (P=0.006); the appropriateness rate was 28.74%, affected by the pathogenic bacteria (P=0.001) and multidrug-resistant microorganism (P=0.001), department (P=0.024), and the length of stay before the empirical therapy (P=0.016).

Conclusion

The susceptibility of bacteria to antibiotics has changed significantly after the breakpoint revision while the clinicians’ empirical therapy failure to change accordingly, which results in the decrease of the appropriateness of empirical use. It is enlightened that we should conduct more research to evaluate the rational use of antibiotics from the laboratory perspective and carry out interventions such as education and supervision to strengthen the collaboration between the microbiology laboratories and clinicians to improve the empirical antibiotic therapy and slow down the antimicrobial resistance.

Duration of post-operative antibiotic treatment in acute complicated appendicitis: systematic review and meta-analysis

BACKGROUND

Appendicitis is the most frequent aetiology of acute abdominal pain requiring surgical treatment, with an estimated lifetime risk between 7% and 8%. Antibiotics play a substantial role in treatment, and there is considerable debate regarding the duration of antibiotics in treating appendicitis.

METHODS

We searched multiple databases from inception until June 2019 for peer-reviewed studies that compared different durations of antibiotic treatment after appendicectomy for acute complicated appendicitis in adults. We dichotomized reported data into short- and extended-term antibiotic use and controlled for different definitional thresholds in the meta-analysis. We generated risk ratios using restricted maximum likelihood methods and mixed effects modelling for each outcome of interest.

RESULTS

Four observational studies involving 847 participants were included in the meta-analysis. For the primary outcomes of intra-abdominal infection, we did not find a statistically significant difference between extended- and short-term antibiotic strategies for intra-abdominal infection (Risk ratio 0.92, 95% confidence interval (CI) 0.49-1.74). Three randomized controlled trials involving 291 participants were included in a separate meta-analysis. We found that extended antibiotic usage was not associated with a statistically significant reduced risk for intra-abdominal infection (RR 0.52, 95% CI 0.21-1.29) or surgical site skin infection (RR 1.44, 95% CI 0.43-4.81).

CONCLUSION

This systematic review and meta-analysis found that extended post-operative antibiotic treatment may not be associated with a reduced risk of intra-abdominal infection; however, meta-analysis was significantly limited by heterogeneity between studies and underpowered trials. Further large randomized controlled trials are needed to confirm these findings.

Outcome of community- versus hospital-acquired intra-abdominal infections in intensive care unit: a retrospective study

Background

To compare patients hospitalised in the intensive care unit (ICU) after surgery for community-acquired intra-abdominal infection (CA-IAI) and hospital-acquired intra-abdominal infection (HA-IAI) in terms of mortality, severity and complications.

Methods

Retrospective study including all patients admitted to 2 ICUs within 48 h of undergoing surgery for peritonitis.

Results

Two hundred twenty-six patients were enrolled during the study period. Patients with CA-IAI had an increased 28-day mortality rate compared to those with HA-IAI (30% vs 15%, respectively (p = 0.009)). At 90 days, the mortality rates were 36.7 and 37.5% in the CA-IAI group and HA-IAI group, respectively, with a similar APACHE II score on admission (median: 21 [15–25] vs. 21 [15–24] respectively, p = 0.63). The patients with HA-IAI had prolonged ICU and hospital stays (median: 17 [7–36] vs. 6[3–12] days, p < 0.001 and 41 [24–66] vs. 17 [7–32] days, p = 0.001), and experienced more complications (reoperation and reintubation) than those with CA-IAI.

Conclusion

CA-IAI group had higher 28-day mortality rate than HA-IAI group. Mortality was similar at 90 days but those with HA-IAI had a prolonged ICU and hospital stay. In addition, they developed more complications.

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.

Identification of Bacterial and Fungal Pathogens in Patients with Post-Laparoscopic Sleeve Gastrectomy Leakage

BACKGROUND

Post-laparoscopic sleeve gastrectomy (LSG) leak leads to serious complications, and death may occur. The microbial pattern should be established in order to plan empirical antimicrobial therapy. The intra-abdominal leaks post-LSG were cultured and reviewed.

METHODS

Microbial cultures collected from all post-sleeve leakage cases managed at the King Khalid University Hospital (KKUH) from May 2011 until April 2016 were reviewed.

RESULTS

A total of 31 patients with positive leak post-LSG were included. The mean presentation time was postoperative day 12. Computed tomography (CT) was done for all patients on presentation with CT-guided aspiration and drainage next day. Samples from the collection were aspirated first for culture then a pigtail drain was kept in place. The average time of drain removal was on the 75th postoperative day. A total of 28 patients (90.3%) had positive culture results. Candida species were the most common organism isolated from 19 patients (61.2%), among them, 10 (32.2%) were positive for Candida species only. Positive bacterial cultures were found in 18 patients (58%). Majority of which single bacterial pathogen isolate, only seven patients had two organisms, and four patients had three organisms. Klebsiella pneumoniae was the most frequent isolated bacteria [8 patients (44.4%)] followed by Streptococcus and Pseudomonas species. Candida albicans was the most common Candida species isolated, 13 patients (68.4%).

CONCLUSION

Fungal microbes isolated from post-LSG leak collection are common and could be considered in the primary empirical therapy. The antibiotic choice for the leak should cover Klebsiella, Streptococcus, and Pseudomonas until definitive culture results are obtained.

Impact of species and antibiotic therapy of enterococcal peritonitis on 30-day mortality in critical care-an analysis of the OUTCOMEREA database

Introduction

Enterococcus species are associated with an increased morbidity in intraabdominal infections (IAI). However, their impact on mortality remains uncertain. Moreover, the influence on outcome of the appropriate or inappropriate status of initial antimicrobial therapy (IAT) is subjected to debate, except in septic shock. The aim of our study was to evaluate whether an IAT that did not cover Enterococcus spp. was associated with 30-day mortality in ICU patients presenting with IAI growing with Enterococcus spp.

Material and methods

Retrospective analysis of French database OutcomeRea from 1997 to 2016. We included all patients with IAI with a peritoneal sample growing with Enterococcus. Primary endpoint was 30-day mortality.

Results

Of the 1017 patients with IAI, 76 (8%) patients were included. Thirty-day mortality in patients with inadequate IAT against Enterococcus was higher (7/18 (39%) vs 10/58 (17%), p = 0.05); however, the incidence of postoperative complications was similar. Presence of Enterococcus spp. other than E. faecalis alone was associated with a significantly higher mortality, even greater when IAT was inadequate. Main risk factors for having an Enterococcus other than E. faecalis alone were as follows: SAPS score on day 0, ICU-acquired IAI, and antimicrobial therapy within 3 months prior to IAI especially with third-generation cephalosporins. Univariate analysis found a higher hazard ratio of death with an Enterococcus other than E. faecalis alone that had an inadequate IAT (HR = 4.4 [1.3–15.3], p = 0.019) versus an adequate IAT (HR = 3.1 [1.0–10.0], p = 0.053). However, after adjusting for confounders (i.e., SAPS II and septic shock at IAI diagnosis, ICU-acquired peritonitis, and adequacy of IAT for other germs), the impact of the adequacy of IAT was no longer significant in multivariate analysis. Septic shock at diagnosis and ICU-acquired IAI were prognostic factors.

Conclusion

An IAT which does not cover Enterococcus is associated with an increased 30-day mortality in ICU patients presenting with an IAI growing with Enterococcus, especially when it is not an E. faecalis alone. It seems reasonable to use an IAT active against Enterococcus in severe postoperative ICU-acquired IAI, especially when a third-generation cephalosporin has been used within 3 months.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2581-8) contains supplementary material, which is available to authorized users.

Antimicrobial susceptibility patterns of organisms causing secondary abdominal infections in patients with perforated abdominal viscus

Background:

Secondary peritonitis, following intestinal perforation, constitutes a significant proportion of cases admitted as a surgical emergency and has a mortality rate of 6–21% worldwide. As a part of an antimicrobial stewardship program, we noted considerable variation among the choice of empirical regimens among such cases. Hence, we conducted a prospective study to generate the evidence for a rational empiric regimen for patients with secondary peritonitis following intestinal perforation.

Methods:

The study included a complete follow up of 77 cases of secondary peritonitis admitted during a 12 month period. The intraoperative fluid (peritoneal) sample of the patient was sent for culture and sensitivity pattern analysis.

Results:

The sites of perforation as seen in decreasing order were lower gastrointestinal (GI) (50.6%), upper GI (36.4%), and unclassified (13%). The most common organism found in the intraoperative fluid was Escherichia coli (47.9%) followed by Klebsiella pneumoniae (12.5%). amikacin, cefoperazone-sulbactam, piperacillin-tazobactam and imipenem were sensitive in 22 (out of 23 tested), 5 (out of 9), 13 (out of 13) and 22 (out of 22) isolates of E. coli and 3 (out of 6), 1 (out of 3), 4 (out of 6), 4 (out of 6) isolates of K. pneumoniae, respectively. The most common empirical antibiotic was cefoperazone-sulbactam (38.7%) followed by piperacillin-tazobactam (29.3%).

Conclusion:

Based on our prospective study, piperacillin-tazobactam or imipenem should be used empirically in patients presenting with complicated intra-abdominal infections secondary to perforated viscus, especially if they have sepsis or septic shock.

Multicenter performance evaluation of the Unyvero IAI cartridge for detection of intra-abdominal infections

Intra-abdominal infections (IAIs) are one of the most common type of infections in patients with sepsis and an important cause of death in intensive care units. Early detection and treatment are necessary to reduce patient complications and improve outcomes. The Unyvero IAI Application (Curetis GmbH) is the first automated assay to rapidly and simultaneously identify a large panel of bacteria, fungi, toxins, and antibiotic resistance markers directly from IAI-related samples. The assay was evaluated in four European clinical laboratories in comparison to routine microbiological practices. A total of 300 clinical samples were tested with an overall sensitivity of 89.3% and specificity of 99.5%, while time to results was reduced by an average of about 17 h compared to identification (ID) results and 41 h compared to full antibiotic susceptibility testing (AST) results. The Unyvero IAI was able to detect additional microorganisms compared with culture, in particular anaerobes, with most detections confirmed by sequencing. The most frequent resistance markers detected were mecA/mecC (n = 25), aacA4 (n = 20), and bla_CTX-M (n = 17) and carbapenemase genes were identified in nine specimens. Further studies are now required to determine the clinical impact of this new rapid test which could play a role in the successful treatment of IAI.

Sepsis and Septic Shock Strategies

Three therapeutic principles most substantially improve organ dysfunction and survival in sepsis: early, appropriate antimicrobial therapy; restoration of adequate cellular perfusion; timely source control. The new definitions of sepsis and septic shock reflect the inadequate sensitivity, specify, and lack of prognostication of systemic inflammatory response syndrome criteria. Sequential (sepsis-related) organ failure assessment more effectively prognosticates in sepsis and critical illness. Inadequate cellular perfusion accelerates injury and reestablishing perfusion limits injury. Multiple organ systems are affected by sepsis and septic shock and an evidence-based multipronged approach to systems-based therapy in critical illness results in improve outcomes.

Unmet needs in the management of intra-abdominal infections

INTRODUCTION

Intra-abdominal infections remain a leading cause of death, morbidity and resource use in surgical wards and intensive care units. The growing complexity of their management has led to new paradigms and unresolved issues in anti-infective therapy described in the current review. Areas covered: We analyzed the literature, recent guidelines, and expert opinions published over the last decade. Expert commentary: Prospective randomized trials are difficult to perform and observational studies or database analyses should be encouraged. Epidemiologic and microbiologic reports should be promoted, especially in developing/resource-limited countries and in specific subpopulations such as children, older people and patients with underlying diseases. The diagnostic process, including imaging procedures, could be improved. The value of biomarkers for diagnosis, monitoring and discontinuation of therapy should be clarified and improved. New microbiologic techniques are needed to speed up the diagnostic process and to improve the adequacy of anti-infective therapy. Very little progress has been made in the detection of clinical failures. Many aspects of anti-infective management, both for bacteria and fungi, remain unresolved, such as the high inoculum, the type of microorganisms to be treated, the timing of therapy, the value of de-escalation, drug monitoring and duration of therapy. New antibiotics are expected.

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.

Management of Severe Sepsis of Abdominal Origin

Severe sepsis is a life-threatening condition that may occur as a sequela of intra-abdominal infections (IAIs) of all types. Diagnosis of IAIs is predicated upon the combination of physical examination and imaging techniques. Diffuse peritonitis usually requires urgent surgical intervention. In the absence of diffuse peritonitis, abdominal computed tomography remains the most useful test for the diagnosis of IAIs, and is essential to both guide therapeutic interventions and evaluate suspected treatment failure in the critically ill patient. Parameters most consistently associated with poor outcomes in patients with IAIs include increased illness severity, failed source control, inadequate empiric antimicrobial therapy, and healthcare-acquired, as opposed to community-acquired infection. Whereas community-acquired IAI is characterized predominantly by enteric gram-negative bacilli and anaerobes that are susceptible to narrow-spectrum agents, healthcare-acquired IAI (e.g., anastomotic dehiscence, postoperative organ-space surgical site infection) frequently involves at least one multi-drug resistant pathogen, necessitating broad-spectrum therapy guided by both culture results and local antibiograms. The cornerstone of effective treatment for abdominal sepsis is early and adequate source control, which is supplemented by antibiotic therapy, restoration of a functional gastrointestinal tract (if possible), and support of organ dysfunction. Furthermore, mitigation of deranged immune and coagulation responses via therapy with recombinant human activated protein C may improve survival significantly in severe cases complicated by septic shock and multiple organ dysfunction syndrome.

Spectrum adequacy of antibiotic regimens for secondary peritonitis: a retrospective analysis in intermediate and intensive care unit patients

Background

Secondary peritonitis requires surgical source control and adequate antimicrobial treatment. Antimicrobial regimens are usually selected according to local susceptibility data of individual pathogens against single agents, but this neglects both the polymicrobial nature of the infection and the use of combination therapy. We analysed the probability of common regimens to cover all relevant pathogens isolated in one patient (“spectrum adequacy rate”, SAR) in a real-life data set.

Methods

Data from 242 patients with secondary peritonitis (88 community acquired, 154 postoperative cases) treated in our IMCU/ICU were obtained retrospectively. The relative frequency of pathogens, resistance rates and the SAR were analysed using the free software R.

Results

Enterococci were isolated in 47.1 % of all patients, followed by Escherichia coli (42.6 %), other enterobacteriaceae (33.1 %), anaerobes (29.8 %) and Candida spp. (28.9 %). Resistance patterns were consistent with general surveillance data from our hospital. The susceptibility rates and SAR were lower in postoperative than in community acquired cases. The following regimens yielded a SAR > 95 % when enterobacteriaceae only were considered: piperacillin/tazobactam + gentamicin, cefotaxim (only for community acquired cases), cefotaxim + gentamicin, meropenem, tigecycline + gentamicin or tigecycline + ciprofloxaxin. When enterococci were also considered, all betalactam based regimens required combination with vancomycin or linezolid for a SAR > 95 %, whereas TGC based regimens were not compromised. As for Candida spp., the SAR of fluconazole was 81.9–87.5 %.

Conclusions

This study demonstrates a rational approach to assess the adequacy of antimicrobial regimens in secondary peritonitis, which may help to adjust local guidelines or to select candidate regimens for clinical studies.

Effect of initial empiric antibiotic therapy combined with control of the infection focus on the prognosis of patients with secondary peritonitis

BACKGROUND

In patients with intra-abdominal infection, inappropriate initial empiric antibiotic therapy is associated with greater morbidity. We evaluated the impact of adequate empiric antibiotic treatment together with control of the infection focus on the morbidity and mortality rates of patients with secondary peritonitis.

METHODS

This was a prospective, observational study with the participation of 24 Spanish hospitals and 362 patients with secondary peritonitis (262 community-acquired, 100 post-operative). Therapeutic failure (infectious complications or death) was classified into four categories according to whether empiric antibiotic treatment was appropriate and the infection focus was controlled.

RESULTS

The rates of therapeutic failure, re-operation, and mortality were 48%, 13%, and 8%, respectively. Empiric antibiotic treatment was inappropriate in 39% of cases, which was associated with a higher rate of surgical site infection (53% vs. 40%; p=0.031) and death (12% vs. 5%; p=0.021) than was observed in patients receiving appropriate initial empiric therapy. Eight percent of patients in whom control of the infection focus was not obtained suffered from more infectious complications (76% vs. 52%; p=0.01) and surgical site infections (69% vs. 44%; p=0.01); and in this group, both therapeutic failure and mortality rates were similar, independent of whether the empiric antibiotic therapy was appropriate.

CONCLUSION

Inappropriate initial empiric antibiotic therapy was associated with higher rates of therapeutic failure, surgical site infection, re-operation, and death. Classification of therapeutic failure into four categories according to the appropriateness of empiric antibiotic therapy and the success of infection control provided excellent discrimination of morbidity and death.

Focus on ceftazidime-avibactam for optimizing outcomes in complicated intra-abdominal and urinary tract infections

INTRODUCTION

Complicated intra-abdominal infections and urinary tract infections are frequently associated with Gram-negative bacteria and treatment can be hampered by the involvement of resistant organisms. A common resistance mechanism is β-lactamase production which confers resistance to β-lactam antibiotics.

AREAS COVERED

This article summarizes β-lactamases found among Gram-negative bacteria as well as providing an overview of complicated intra-abdominal infections and urinary tract infections and the impact inappropriate antibiotic therapy and antibiotic resistance has in their treatment. The author reviews the activity of ceftazidime-avibactam , including animal model data and microbiological data from Phase II clinical trials. This article also highlights Phase III clinical trials of ceftazidime-avibactam that are ongoing or completed and briefly discusses other β-lactamase inhibitor combinations currently in development.

EXPERT OPINION

The increasing problem and complexity of β-lactamase resistance has been met by resurgence in the development of β-lactamase inhibitor combinations. These show promise in the treatment of resistant infections. One β-lactamase inhibitor in advanced development with a broad spectrum of activity is avibactam, covering class A, class C and some class D enzymes. Importantly, the activity of avibactam also includes carbapenemases such as the KPC and OXA-48. The combination of avibactam with the cephalosporin ceftazidime is attractive, given the spectrum of antimicrobial activity and the low toxicity of the cephalosporin class.

Guidelines for management of intra-abdominal infections

Intra-abdominal infections are one of the most common gastrointestinal emergencies and a leading cause of septic shock. A consensus conference on the management of community-acquired peritonitis was published in 2000. A new consensus as well as new guidelines for less common situations such as peritonitis in paediatrics and healthcare-associated infections had become necessary. The objectives of these Clinical Practice Guidelines (CPGs) were therefore to define the medical and surgical management of community-acquired intra-abdominal infections, define the specificities of intra-abdominal infections in children and describe the management of healthcare-associated infections. The literature review was divided into six main themes: diagnostic approach, infection source control, microbiological data, paediatric specificities, medical treatment of peritonitis, and management of complications. The GRADE(®) methodology was applied to determine the level of evidence and the strength of recommendations. After summarising the work of the experts and application of the GRADE(®) method, 62 recommendations were formally defined by the organisation committee. Recommendations were then submitted to and amended by a review committee. After 2 rounds of Delphi scoring and various amendments, a strong agreement was obtained for 44 (100%) recommendations. The CPGs for peritonitis are therefore based on a consensus between the various disciplines involved in the management of these patients concerning a number of themes such as: diagnostic strategy and the place of imaging; time to management; the place of microbiological specimens; targets of empirical anti-infective therapy; duration of anti-infective therapy. The CPGs also specified the value and the place of certain practices such as: the place of laparoscopy; the indications for image-guided percutaneous drainage; indications for the treatment of enterococci and fungi. The CPGs also confirmed the futility of certain practices such as: the use of diagnostic biomarkers; systematic relaparotomies; prolonged anti-infective therapy, especially in children.

Resistance Rates of Intra-Abdominal Isolates from Intensive Care Units and Non-Intensive Care Units in the United States: The Study for Monitoring Antimicrobial Resistance Trends 2010-2012

BACKGROUND

Enterobacteriaceae (3,235 isolates), Pseudomonas aeruginosa (476 isolates), and Acinetobacter baumannii (106 isolates) from inpatient intra-abdominal infections (IAIs) were collected for the 2010-2012 Study for Monitoring Antimicrobial Resistance Trends (SMART) program in the United States. This report evaluates the in vitro activity of several antimicrobial agents recommended for treatment of IAIs and compares profiles of isolates from intensive care units (ICUs) and non-intensive care units (non-ICUs).

METHODS

Gram-negative bacilli from hospitalized patients with IAIs were obtained each year from 2010-2012 from hospitals in the United States and tested for susceptibility to 12 antibiotics according to 2012 Clinical and Laboratory Standards Institute (CLSI) guidelines.

RESULTS

The most active agents against members of the Enterobacteriaceae family from both ICUs and non-ICUs were amikacin, ertapenem, and imipenem-cilastatin, whereas the least active agent was ampicillin-sulbactam. Amikacin was the only agent with good activity against P. aeruginosa, whereas none of the agents tested exhibited substantial activity against A. baumannii. Amikacin, ceftazidime, ceftriaxone, ciprofloxacin, levofloxacin, and imipenem-cilastatin were significantly less active against Enterobacteriaceae from ICU patients, whereas cefepime and ceftazidime were significantly less active against P. aeruginosa from ICU patients. Intensive care unit isolates were more likely to be multi-drug-resistant than non-ICU isolates, although there was no difference in extended-spectrum β-lactamase (ESBL) production rates between the two patient groups.

CONCLUSIONS

Despite increasing resistance trends, in this study amikacin, ertapenem, and imipenem-cilastatin were shown to have good in vitro activity against the most frequently isolated gram-negative bacilli from IAIs in ICU and non-ICU settings.

Characteristics of surgical patients receiving inappropriate empiric antimicrobial therapy

BACKGROUND

Inappropriate antibiotics have been observed to result in an increased duration of antibiotic treatment and hospital length of stay, development of multidrug-resistant organisms, and mortality rate compared with appropriate antibiotic treatment. Few studies have evaluated independent risk factors associated with inappropriateness. The purpose of this study was to identify independent predictors of inappropriate, empiric antimicrobial therapy for the treatment of severe sepsis.

METHODS

This was a retrospective analysis of a prospectively maintained database of all surgical/trauma patients admitted to a tertiary care center from 1996 to 2007 and treated for sepsis. "Appropriate" empiric antibiotic treatment was determined by sensitivity testing. Demographics and comorbidities, infection sites, infection organisms, and outcomes between strata were compared. Differences in outcome were estimated using relative risk and 95% confidence intervals for correlated data.

RESULTS

A total of 2,855 patients (7,158 infections) were identified. Independent predictors of inappropriate, empiric antimicrobial therapy for the treatment of severe sepsis included site of infection and organism type. Severity of illness, age, medical conditions, and community versus health care-associated infections were not associated with inappropriate therapy. Although inappropriate empiric therapy was associated with a longer length of stay and duration of antimicrobial use, it did not result in higher mortality.

CONCLUSION

Our study observed that inappropriate empiric antibiotic selection is related to site of infection and pathogen. Other clinical variables do not appear to predict inappropriateness of antibiotic treatment. Efforts should be focused on early broad-spectrum therapy and more rapid microbiologic methods.

LEVEL OF EVIDENCE

Therapeutic/care management study, level II.

Clinical and Economic Consequences of Failure of Initial Antibiotic Therapy for Hospitalized Patients With Complicated Skin and Skin-Structure Infections

Objective.

To estimate the consequences of failure of initial antibiotic therapy for patients with complicated skin and skin-structure infections.

Design.

Retrospective cohort study.

Setting.

Large US multihospital database.

Patients.

We identified a total of 47,219 patients (age 18 years or older) who were admitted to the hospital for complicated skin and skin-structure infections from April 1, 2003, through March 31, 2004, and who received intravenous antibiotics during the first 2 hospital-days (ie, initial antibiotic therapy). Failure of therapy was defined as drainage, debridement, or receipt of other intravenous antibiotics at any subsequent time (except for changes to narrower-spectrum agents or any therapy change immediately before discharge). Predictors of failure of antibiotic therapy and mortality were examined using multivariate logistic regression. Analysis of covariance was used to estimate the impact of treatment failure on duration of intravenous antibiotic therapy, length of stay, and total inpatient charges.

Results.

For 10,782 admitted patients (22.8%), there was evidence of failure of initial antibiotic therapy. In multivariate analyses, treatment failure was associated with receipt of vasoactive medications during the first 2 hospital-days (odds ratio [OR], 1.66 [95% confidence interval {CI}, 1.19-2.31]), initiation of antibiotic therapy in the intensive care unit (OR, 1.53 [95% CI, 1.28-1.84]), and the patient's Charlson comorbidity index (OR per 1-point increase, 1.06 [95% CI, 1.04-1.08]); treatment failure was also was associated with a 3-fold increase in mortality (OR, 2.91 [95% CI, 2.34-3.62]). Compared with patients for whom initial treatment was successful, patients who experienced treatment failure received intravenous antibiotic therapy for a mean of 5.7 additional days, were hospitalized for a mean of 5.4 additional days, and incurred a mean of $5,285 (in 2003 dollars) in additional inpatient charges (all P <.01).

Conclusion.

Failure of initial antibiotic therapy in the treatment of complicated skin and skin-structure infections is associated with significantly worse clinical and economic outcomes.

Impact of Surgical Infection Society/Infectious Disease Society of America-recommended antibiotics on postoperative intra-abdominal abscess with image-guided percutaneous abscess drainage following gastrointestinal surgery

PURPOSE

The aims of this study were to reveal how using the antibiotics recommended by the 2010 Surgical Infection Society (SIS) and Infectious Disease Society of America (IDSA) guidelines can affect the therapeutic outcomes.

METHODS

We reviewed the cases of 53 patients with a postoperative intra-abdominal abscess without anastomotic leakage after gastrointestinal surgery who underwent image-guided percutaneous abscess drainage (PAD) and concomitant antibiotic therapy. The type of antibiotic initially administered was determined based on the surgeon's judgment. A persistent abscess was defined as one or more PAD procedures resulting in complete resolution after 21 or more days. The recommended antibiotics were defined according to 2010 SIS/IDSA guidelines.

RESULTS

All 53 patients had complete resolution without the need for surgery. The results of a multivariable analysis revealed that a C-reactive protein level ≥12 mg/dL and non-recommended antibiotics were significant risk factors for a persistent abscess (P = 0.042 and 0.013, respectively). With regard to a fever lasting more than 48 h, there was a significant difference between the recommended (45.1%) and non-recommended (72.7 %) antibiotic groups (P = 0.046).

CONCLUSIONS

Using the recommended antibiotics may shorten the time to defervescence and reduce the risk of a persistent abscess in patients undergoing PAD for a postoperative abscess after gastrointestinal surgery.

What is the impact of a rapid diagnostic E-test in the treatment of patients with Gram-negative bacteraemia?

OBJECTIVE

To evaluate the influence of a rapid diagnostic test (RDT) in antibiotic therapeutic decisions in non-paediatric patients with Gram-negative bacteraemia (GNB).

PATIENTS AND METHODS

A RDT consisting of a direct antibiogram was used on blood isolates of GNB. GNB were also identified and sensitivity tests were performed according to standard criteria. Information on empirical treatment was registered (T1), as well as the antibiotic administered once the results of the RDT were available (T2). Finally, we noted the ideal antibiotic that the infectious diseases specialist (IDS) would have prescribed (T3). The decision regarding T2 was always taken by the patient's physician or the physician on duty.

RESULTS

A RDT was performed for 248 patients. The most frequently isolated bacterium was Escherichia coli (13% producing extended-spectrum beta-lactamase). T1 was considered appropriate in 74% and appropriate but optimizable in 43%. T2 was considered appropriate in 95%, appropriate but optimizable in 36%, and inappropriate in 5%. The cost of the optimizable treatment (T2) was € 2210, while the cost of the ideal treatment would have been € 416; the saving in antibiotic cost of 1 day of treatment would have been € 1694.

CONCLUSIONS

Treatment prescribed by a non-IDS after a RDT was inappropriate in 5% and optimizable in 36%. It is our recommendation that information provided by a RDT should be interpreted by an IDS to make the information more beneficial both economically and 'ecologically'.

Initial treatment failure in patients with complicated skin and skin structure infections

BACKGROUND

Consequences of initial antibiotic failure in patients hospitalized for complicated skin and skin-structure infections (cSSSI) are not well understood.

METHODS

Using data from >100 hospitals in the United States, we identified all adults hospitalized for cSSSI between January 1, 2000 and June 30, 2009. We defined "initial therapy" as all parenteral antibiotics administered <24 h of admission, and such therapy was assumed to have failed if the patient (1) received new antibiotic(s) subsequently (excluding similar/narrower spectrum antibiotics or those begun at discharge), or (2) underwent drainage/debridement/amputation>72 h after admission. We limited attention to the 40 most commonly used antibiotic regimens in 2009. We compared clinical and economic outcomes of patients who experienced initial treatment failure and those who did not.

RESULTS

The rate of initial treatment failure was 16.6% in acute infections (n=13,498), 34.1% in chronic/ulcerative infections (n=1,116), and 26.7% in surgical site infections (SSIs) (n=2,929). Treatment failure was associated with 4.1-7.3 additional days in the hospital and $11,995-$23,655 in additional inpatient charges; the case fatality rate was from 4- to 12-fold higher in patients who experienced treatment failure than in those who did not (all comparisons, p<0.01).

CONCLUSION

Initial treatment failure in patients hospitalized for cSSSI is associated with significantly worse clinical outcomes, longer hospital stays, and higher hospital charges than with successful initial treatment.

Epidemiology and susceptibility of Gram-negative appendicitis pathogens: SMART 2008-2010

BACKGROUND

The Study for Monitoring Antimicrobial Resistance Trends (SMART) has tracked the in vitro activity of ertapenem and comparators against aerobic gram-negative bacteria from intra-abdominal infections since 2002. This report describes the epidemiology and susceptibility for clinical isolates associated with appendicitis, collected from 2008 to 2010.

METHODS

A total of 1,720 gram-negative bacilli were collected from patients with appendicitis in 122 hospitals in 39 countries worldwide; of these, 23% of isolates were from pediatric patients (≤ 17 years old). Minimum inhibitory concentrations (MICs) and extended-spectrum β-lactamase (ESBL) phenotypes were determined by broth microdilution and interpreted using Clinical and Laboratory Standards Institute guidelines.

RESULTS

The global ESBL-positive rate was 16.3%, ranging from 2.2% for Proteus mirabilis to 16.6% for Escherichia coli and 20.1% for Klebsiella pneumoniae. The ESBL-positive rates differed by age group (17.7% in adults vs. 11.4% in children) and by geographic region, with significantly higher rates in Asia/Pacific (28.0%) and significantly lower rates in North America (9.1%), Africa/Middle East (4.8%), and Europe (4.4%). Amikacin, imipenem-cilastatin, piperacillin-tazobactam, and ertapenem were the most active of the tested agents against aerobic gram-negative appendicitis pathogens across pediatric and adult age groups and across geographic regions, including ESBL-positive isolates. Cefepime and ceftazidime were active against ≥ 90% of global pediatric isolates. E. coli, by far the most frequently isolated species (68% in adults and 75% in pediatric patients), was significantly less susceptible in adults than in pediatric patients (p<0.05; Fisher exact test) to all tested agents except amikacin, ertapenem, imipenem-cilastatin, piperacillin-tazobactam, and ampicillin-sulbactam (with the latter showing low activity in both age groups).

CONCLUSIONS

These in vitro data suggest that amikacin, imipenem-cilastatin, piperacillin-tazobactam, and ertapenem would perform well against aerobic gram-negative bacilli associated with appendicitis in both adults and children, especially in regions with high rates of ESBL-positive E. coli.

Combination therapy for treatment of infections with gram-negative bacteria

Combination antibiotic therapy for invasive infections with Gram-negative bacteria is employed in many health care facilities, especially for certain subgroups of patients, including those with neutropenia, those with infections caused by Pseudomonas aeruginosa, those with ventilator-associated pneumonia, and the severely ill. An argument can be made for empiric combination therapy, as we are witnessing a rise in infections caused by multidrug-resistant Gram-negative organisms. The wisdom of continued combination therapy after an organism is isolated and antimicrobial susceptibility data are known, however, is more controversial. The available evidence suggests that the greatest benefit of combination antibiotic therapy stems from the increased likelihood of choosing an effective agent during empiric therapy, rather than exploitation of in vitro synergy or the prevention of resistance during definitive treatment. In this review, we summarize the available data comparing monotherapy versus combination antimicrobial therapy for the treatment of infections with Gram-negative bacteria.

Antimicrobial management of intra-abdominal infections: Literature's guidelines

Antimicrobial management of severe intra-abdominal infections (IAIs) involves a delicate balance of optimizing empirical therapy, which has been shown to improve clinical outcomes, while simultaneously reducing unnecessary antimicrobial use. Two sets of guidelines for the management of intra-abdominal infections were recently published. In 2010, the Surgical Infection Society and the Infectious Diseases Society of America (SIS-IDSA) created guidelines for the diagnosis and management of complicated IAIs. The new SIS-IDSA guidelines replace those previously published in 2002 and 2003. The World Society of Emergency Surgery (WSES) guidelines represent additional contributions, made by specialists worldwide, to the debate regarding proper antimicrobial drug methodology. These guidelines represent the conclusions of the consensus conference held in Bologna, Italy, in July 2010 during the first congress of the WSES.

Efficacy of therapy with recombinant human activated protein C of critically ill surgical patients with infection complicated by septic shock and multiple organ dysfunction syndrome

BACKGROUND

Septic shock causing or complicating critical surgical illness results in high mortality. Drotrecogin alfa (activated), known also as recombinant human activated protein C (rhAPC) has become controversial as therapy, owing to persisting questions of efficacy and safety. We hypothesized rhAPC to be effective therapy for critically ill surgical patients with septic shock.

METHODS

Open-label therapy with rhAPC (by predefined criteria) of 108 critically ill surgical patients. Treated patients were matched individually in prospect for age, gender, Acute Physiology and Chronic Health Evaluation (APACHE)-II and -III scores, site of infection, and organism (0-2 points each, maximum 12 points) with 108 patients from our 15,000-patient surgical intensive care unit database who did not receive rhAPC. No match was accepted if <6 points. Multiple organ dysfunction (MOD) scores and data regarding cortisol concentrations, bleeding complications, and transfusion requirements were collected. The primary endpoint was 28-day mortality, with mortality for hospitalization and resolution of organ dysfunction as secondary endpoints. Statistical analyses included ANOVA, c statistic, binary logistic regression, and Kaplan-Meier time-to-event and Cox proportional hazards analyses; α=0.05.

RESULTS

The mean match score was 9.2±0.1 points (range, 6-12 points). Patients were well matched by all criteria, including baseline MOD score (9.5±0.7 vs. 9.8±0.3 points, p=0.66). Mean age was 68.1±1.1 years (p=0.49), Mean APACHE-III score was 99.6±1.5 points (p=0.87). Mean time to rhAPC administration was 25±3 h. Survival at 28 days after rhAPC was 71.3% vs. 49.1% (p=0.001); hospital survival was 57.4% vs. 40.7% (p=0.02). By logistic regression, rhAPC therapy resulted in improved 28-day survival (OR 2.57, 95% CI 1.46-4.52, p=0.001) (model χ2 11.244, p=0.001); and hospital survival (OR 1.96, 95% CI 1.14-3.36, p=0.015) (model χ2 6.03, p=0.014). The MOD score decreased significantly (p=0.012) during rhAPC therapy.

CONCLUSION

Therapy with rhAPC appeared to improve survival in surgical ICU patients with life-threatening infection characterized by septic shock and organ dysfunction.

Empiric antibiotic selection strategies for healthcare-associated pneumonia, intra-abdominal infections, and catheter-associated bacteremia

Initial selection and early deployment of appropriate/adequate empiric antimicrobial therapy is critical to minimize the significant morbidity and mortality associated with hospital- or healthcare-associated infections (HAIs). Initial empiric therapy that inadequately covers the pathogen(s) causing a serious HAI has been associated with increased mortality, longer hospital stay, and elevated healthcare costs. Moreover, subsequent modification of initial inadequate therapy, later in the disease process when culture results become available, may not remedy the impact of the initial choice. Because of this, it is important that initial empiric therapy covers the most likely pathogens associated with infection in a particular patient, even if this initial regimen turns out to be unnecessarily broad, based on subsequent culture results. The current paradigm for management of serious HAIs is to initiate empiric therapy with a broad-spectrum regimen covering likely pathogens, based on local surveillance and susceptibility data, and presence of risk factors for involvement of a resistant microorganism. Subsequent modification (de-escalation) of the initial regimen becomes possible later, when culture results are available and clinical status can be better assessed, 2 to 4 days after initiation of empiric therapy. When possible, de-escalation and other steps to modify antimicrobial exposure are important for minimizing risk of antimicrobial resistance development. This article examines the general process for selection of initial empiric antibiotic therapy for patients with HAIs, illustrated through 3 case studies dealing with healthcare-associated pneumonia, complicated intra-abdominal infection, and catheter-associated bacteremia, respectively.

Complicated Intra-Abdominal Infections Observational European study (CIAO Study)

Complicated intra-abdominal infections are frequently associated with poor prognoses and high morbidity and mortality rates.

Despite advances in diagnosis, surgery, and antimicrobial therapy, mortality rates associated with complicated intra-abdominal infections remain exceedingly high.

In order to describe the clinical, microbiological, and management-related profiles of both community-acquired and healthcare-acquired complicated intra-abdominal infections (IAIs), the World Society of Emergency Surgery (WSES), in collaboration with the Surgical Infections Society of Europe (SIS-E) and other prominent European surgical societies, has designed the CIAO study.

The CIAO study is a multicenter, observational study and will be carried out in various surgical departments throughout Europe. The study will include patients undergoing surgery or interventional drainage for complicated IAI.

Antimicrobial therapy of sepsis and septic shock--when are two drugs better than one?

In clinical practice, physicians frequently use combination therapy despite the conflicting evidence for its effectiveness. The results of recent studies have contributed to our understanding of this important issue. In this article, we examine the evidence for, or against, the use of combination drug therapy compared with monotherapy in the management of serious infections, sepsis, and septic shock.

Enterococci increase the morbidity and mortality associated with severe intra-abdominal infections in elderly patients hospitalized in the intensive care unit

OBJECTIVES

Enterococci may increase morbidity and mortality in elderly patients with intra-abdominal infections (IAIs) hospitalized in the intensive care unit (ICU).

PATIENTS AND METHODS

A single-centre, retrospective evaluation of an ICU database (1997-2007) of elderly ICU patients (≥75 years) with a severe IAI was performed. Demographics, severity scores, underlying diseases, microbiology and outcomes were recorded. Patients with enterococci isolated in peritoneal fluid (E+ group) were compared with those lacking enterococci in peritoneal fluid (E- group). Stepwise multivariate logistic regression was used to identify independent factors associated with mortality.

RESULTS

One hundred and sixty patients were included (mean ± SD age 82 ± 5 years; n = 72 in the E+ group). The E+ group was more severely ill than the E- group, with higher Simplified Acute Physiologic Score 2 (61 ± 20 versus 48 ± 16, P = 0.0001) and Sequential Organ Failure Assessment scores (8 ± 3 versus 5 ± 3, P = 0.0001), a greater postoperative infection rate (58.3% versus 34.1%, P = 0.01), a higher incidence of inappropriate empirical antimicrobial therapies (33.3% versus 19.3%, P = 0.04), a longer duration of mechanical ventilation (11.8 ± 10.9 versus 7.8 ± 10.2 days, P = 0.02) and greater vasopressor use (7.2 ± 7.1 versus 3.3 ± 4.1 days, P = 0.001). ICU mortality was higher in the E+ group than in the E- group (54.2% versus 38.6%, P = 0.05). In the multivariate analysis, E+ status was independently associated with mortality (odds ratio 2.24; 95% confidence interval 1.06-4.75; P = 0.03).

CONCLUSIONS

In severely ill, elderly patients in the ICU for an IAI, the isolation of enterococci was associated with increased disease severity and morbidity and was an independent risk factor for mortality.

Susceptibility of Klebsiella pneumoniae isolates from intra-abdominal infections and molecular characterization of ertapenem-resistant isolates

A total of 2,841 clinical isolates of Klebsiella pneumoniae from intra-abdominal infections worldwide were collected in the Study for Monitoring Antimicrobial Resistance Trends (SMART) during 2008 and 2009. Overall, 22.4% of isolates had extended-spectrum β-lactamases (ESBLs). The most active antibiotics among the 11 tested were imipenem, amikacin, and ertapenem, though even these, like all other comparators, were less consistently active against ESBL-positive isolates than against ESBL-negative isolates. Globally, 6.5% of isolates were ertapenem resistant based on the June 2010 clinical breakpoints published by the Clinical and Laboratory Standards Institute, with MICs of ≥1 μg/ml. Molecular characterization of 43 isolates with ertapenem MICs of ≥4 μg/ml showed that they variously produced CTX-M or SHV ESBLs combined with altered impermeability and/or had KPC (n = 28), OXA-48 (n = 3), or VIM (n = 1) carbapenemases. Further monitoring of ertapenem susceptibility and molecular characterization of ertapenem-resistant isolates are needed.

[What should and should not be covered in intraabdominal infection]

Despite improvements in our knowledge of the physiopathology of severe infection, diagnostic methods, antibiotic therapy, postoperative care and surgical techniques, a substantial number of patients with intraabdominal infection (IAI) will develop advanced stages of septic insult requiring admission to the intensive care unit. The success of treatment of IAI is multifactorial and the best antibiotic protocol may be insufficient unless adequate control of the focus of infection has been achieved. The present article discusses the appropriacy of empirical antibiotic therapy and the main pathogens associated with treatment failure. We also analyze the patients at risk of infection with microorganisms requiring broad-spectrum antimicrobial coverage. However, excessive antibiotic treatment, in terms of either spectrum or duration, could jeopardize future patients in an environment already threatened by the scarcity of research and development into new molecules required for the emergence of pathogens resistant to current antibiotics.