Effect of inappropriate initial empiric antibiotic therapy on outcome of patients with community-acquired intra-abdominal infections requiring surgery

Respiratory distress and chest pain: a perforated peptic ulcer with an unusual presentation

Background

Dyspnea and chest pain are common presenting complaints to the ED, and coupled together can present a challenging diagnostic dilemma in patients in extremis. A thoughtful evaluation is required, giving due diligence to the immediate life threats as well as multiple etiologies which can cause serious morbidity. A perforated peptic ulcer is one such possibility and requires rapid diagnosis and prompt intervention to avoid the associated high risk of morbidity and mortality.

Method

We present a case report of a 54 year old man with respiratory distress and chest pain as the initial Emergency Department presentation of a perforated duodenal ulcer.

Results

We discuss an unusual presentation of a perforated duodenal ulcer that was recognized in the emergency department and treated promptly. The patient was surgically treated immediately, had a prolonged and complicated post-operative course, but is ultimately doing well. We also provide a brief literature review of the risk factors, imaging choices, and management decision required to treat a perforated ulcer.

Conclusions

Perforated ulcers can have highly varied presentations and are occasionally difficult to diagnose in a complicated patient. Knowledge of the risk factors and a thorough history and physical can point to the diagnosis, but timely and appropriate imaging is often required because delays in diagnosis and treatment lead to poor outcomes. Early administration of antibiotics and immediate surgical repair are necessary to limit morbidity and mortality.

Timing of correct parenteral antibiotic initiation and outcomes from severe bacterial community-acquired pneumonia in children

BACKGROUND

The impact of timing of appropriate antibiotic initiation for critically ill children with severe bacterial community-acquired pneumonia (CAP) is unknown. We hypothesized that longer time to initiation of correct parenteral antibiotic would be associated with longer durations of mechanical ventilation, intensive care unit length of stay, and hospital length of stay.

METHODS

We retrospectively reviewed medical records of children admitted to Nationwide Children's Hospital between January 2004 and December 2006 with bacterial CAP treated with mechanical ventilation, excluding those with documented viral infection. Time to correct antibiotic was defined as time from presentation to any emergency department to the initiation of a parenteral antibiotic to which cultured pathogens were susceptible.

RESULTS

In all, 45 patients, median age 17 months, were identified. Median time to correct antibiotic was 10.3 hours, with 71% of patients receiving correct empiric therapy. After adjusting for severity of illness, longer time to correct antibiotic was independently associated with longer hospital stay (P = 0.007). For the 23 patients in the cohort for whom pneumonia was the primary diagnosis, longer time to correct antibiotic was independently associated with longer durations of mechanical ventilation (P = 0.01), intensive care unit stay (P = 0.001), and hospital stay (P = 0.006). Delays in antibiotic administration as short as 2 to 4 hours were associated with adverse outcomes in this group.

CONCLUSIONS

In our critically ill children with severe bacterial CAP, longer delays in receipt of appropriate empiric antibiotics were independently associated with adverse outcomes.

[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.

The Microbiology of Community-acquired Peritonitis in Children

BACKGROUND

microbiologic data are lacking regarding pediatric community-acquired peritonitis (CAP).

METHODS

we conducted a 2-year retrospective single center study. Consecutive children undergoing CAP surgery were included. Microbiology and antimicrobial susceptibility of peritoneal isolates were analyzed.

RESULTS

a total of 70 children from 3 months to 14 years of age were included. A total of 123 bacterial isolates were analyzed. Escherichia coli was the predominant aerobic organism (51% of isolates); 54.8% were susceptible to amoxicillin whereas 90.3% were susceptible to amoxicillin-clavulanate. Anaerobes accounted for 29% of isolates, and 94.3% of strains were susceptible to amoxicillin-clavulanate and 68.5% were susceptible to clindamycin. Pseudomonas aeruginosa was present in 6% of isolates and in 10% of children. The presence of E. coli resistant to amoxicillin or to amoxicillin-clavulanate was the only independent risk factor associated with postoperative peritonitis.

CONCLUSION

microbiology of pediatric CAP is similar to adult CAP with a predominancy of E. coli and anaerobes. P. aeruginosa in peritoneal samples had no apparent influence on the outcome.

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.

A multicentre, open-label, randomized comparative study of tigecycline versus ceftriaxone sodium plus metronidazole for the treatment of hospitalized subjects with complicated intra-abdominal infections

Tigecycline (TGC) has demonstrated clinical efficacy and safety, in comparison with imipenem/cilastatin in phase 3 clinical trials, for complicated intra-abdominal infection (cIAI). The present study comprised a multicentre, open-label, randomized study of TGC vs. ceftriaxone plus metronidazole (CTX/MET) for the treatment of patients with cIAI. Eligible subjects were randomized (1:1) to receive either an initial dose of TGC (100 mg) followed by 50 mg every 12 h or CTX (2 g once daily) plus MET (1-2 g daily), for 4-14 days. The primary endpoint was the clinical response in the clinically evaluable (CE) population at the test of cure (TOC) assessment. Of 473 randomized subjects, 376 were CE. Among these, clinical cure rates were 70.4% (133/189) with TGC vs. 74.3% (139/187) with CTX/MET (95% CI -13.1 to 5.1; p 0.009 for non-inferiority). Clinical cure rates for subjects with Acute Physiological and Chronic Health Evaluation II scores > or =10 were 56.8% (21/37) with TGC vs. 58.3% (21/36) with CTX/MET. The microbiologic response was similar between the two treatment arms, with microbiological eradication at TOC achieved in 68.1% (94/138) of TGC-treated subjects and 71.5% (98/137) of CTX/MET-treated subjects. (The most frequently reported adverse events (AEs) for both treatment arms were nausea (TGC, 38.6% vs CTX/MET, 27.7%) and vomiting (TGC, 23.3% vs CTX/MET, 17.7%). Overall discontinuation rates as a result of an AE were 8.9% and 4.8% in TGC- and comparator-treated subjects, respectively. The results obtained in the present study demonstrate that TGC monotherapy is non-inferior to a combination regimen of CTX/MET with respect to treating subjects with cIAI.

Antibiotic optimization in the difficult-to-treat patient with complicated intra-abdominal or complicated skin and skin structure infections: focus on tigecycline

Complicated intra-abdominal and skin and skin structure infections are widely varied in presentation. These infections very often lead to an increase in length of hospital stay, with a resulting increase in costs and mortality. In addition, these infections may be caused by a wide variety of bacteria and are often polymicrobial with the possibility of the presence of antimicrobial-resistant strains, such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended-spectrum β-lactamase strains (Escherichia coli, Klebsiella pneumoniae), and K. pneumoniae carbapenemase-producing strains. In combination with patients’ immunosuppression or comorbidities, the treatment and management options for initial therapy success are few. Tigecycline, a new glycylcyline antimicrobial from the tetracycline drug class, represents a viable option for the successful treatment of these infections. It has been shown to have activity against a wide variety of bacteria, including the antimicrobial-resistant strains. As with all tetracycline drugs, it is not recommended for pregnant or nursing women. The potential side effects are those typical of tetracycline drugs: nausea, vomiting, and headaches. Drug–drug interactions are not expected, and renal function monitoring is not necessary.

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.

Efficacy and safety of tigecycline monotherapy vs. imipenem/cilastatin in Chinese patients with complicated intra-abdominal infections: a randomized controlled trial

Background

Tigecycline, a first-in-class broad-spectrum glycylcycline antibiotic, has broad-spectrum in vitro activity against bacteria commonly encountered in complicated intra-abdominal infections (cIAIs), including aerobic and facultative Gram-positive and Gram-negative bacteria and anaerobic bacteria. In the current trial, tigecycline was evaluated for safety and efficacy vs. imipenem/cilastatin in hospitalized Chinese patients with cIAIs.

Methods

In this phase 3, multicenter, open-label study, patients were randomly assigned to receive IV tigecycline or imipenem/cilastatin for ≤2 weeks. The primary efficacy endpoints were clinical response at the test-of-cure visit (12-37 days after therapy) for the microbiologic modified intent-to-treat and microbiologically evaluable populations. Because the study was not powered to demonstrate non-inferiority between tigecycline and imipenem/cilastatin, no formal statistical analysis was performed. Two-sided 95% confidence intervals (CIs) were calculated for the response rates in each treatment group and for differences between treatment groups for descriptive purposes.

Results

One hundred ninety-nine patients received ≥1 dose of study drug and comprised the modified intent-to-treat population. In the microbiologically evaluable population, 86.5% (45 of 52) of tigecycline- and 97.9% (47 of 48) of imipenem/cilastatin-treated patients were cured at the test-of-cure assessment (12-37 days after therapy); in the microbiologic modified intent-to-treat population, cure rates were 81.7% (49 of 60) and 90.9% (50 of 55), respectively. The overall incidence of treatment-emergent adverse events was 80.4% for tigecycline vs. 53.9% after imipenem/cilastatin therapy (P < 0.001), primarily due to gastrointestinal-related events, especially nausea (21.6% vs. 3.9%; P < 0.001) and vomiting (12.4% vs. 2.0%; P = 0.005).

Conclusions

Clinical cure rates for tigecycline were consistent with those found in global cIAI studies. The overall safety profile was also consistent with that observed in global studies of tigecycline for treatment of cIAI, as well as that observed in analyses of Chinese patients in those studies; no novel trends were observed.

Trial Registration

ClinicalTrials.gov NCT00136201

Diagnosis and management of complicated intra-abdominal infection in adults and children: guidelines by the Surgical Infection Society and the Infectious Diseases Society of America

Evidence-based guidelines for managing patients with intra-abdominal infection were prepared by an Expert Panel of the Surgical Infection Society and the Infectious Diseases Society of America. These updated guidelines replace those previously published in 2002 and 2003. The guidelines are intended for treating patients who either have these infections or may be at risk for them. New information, based on publications from the period 2003-2008, is incorporated into this guideline document. The panel has also added recommendations for managing intra-abdominal infection in children, particularly where such management differs from that of adults; for appendicitis in patients of all ages; and for necrotizing enterocolitis in neonates.

Risk factors for multidrug resistant bacteria and optimization of empirical antibiotic therapy in postoperative peritonitis

Introduction

The main objective was to determine risk factors for presence of multidrug resistant bacteria (MDR) in postoperative peritonitis (PP) and optimal empirical antibiotic therapy (EA) among options proposed by Infectious Disease Society of America and the Surgical Infection Society guidelines.

Methods

One hundred patients hospitalised in the intensive care unit (ICU) for PP were reviewed. Clinical and microbiologic data, EA and its adequacy were analysed. The in vitro activities of 9 antibiotics in relation to the cultured bacteria were assessed to propose the most adequate EA among 17 regimens in the largest number of cases.

Results

A total of 269 bacteria was cultured in 100 patients including 41 episodes with MDR. According to logistic regression analysis, the use of broad-spectrum antibiotic between initial intervention and reoperation was the only significant risk factor for emergence of MDR bacteria (odds ratio (OR) = 5.1; 95% confidence interval (CI) = 1.7 - 15; P = 0.0031). Antibiotics providing the best activity rate were imipenem/cilastatin (68%) and piperacillin/tazobactam (53%). The best adequacy for EA was obtained by combinations of imipenem/cilastatin or piperacillin/tazobactam, amikacin and a glycopeptide, with values reaching 99% and 94%, respectively. Imipenem/cilastin was the only single-drug regimen providing an adequacy superior to 80% in the absence of broad spectrum antibiotic between initial surgery and reoperation.

Conclusions

Interval antibiotic therapy is associated with the presence of MDR bacteria. Not all regimens proposed by Infectious Disease Society of America and the Surgical Infection Society guidelines for PP can provide an acceptable rate of adequacy. Monotherapy with imipenem/cilastin is suitable for EA only in absence of this risk factor for MDR. For other patients, only antibiotic combinations may achieve high adequacy rates.

Multicenter study evaluating the role of enterococci in secondary bacterial peritonitis

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

Diagnosis and Management of Complicated Intra-abdominal Infection in Adults and Children: Guidelines by the Surgical Infection Society and the Infectious Diseases Society of America

Evidence-based guidelines for managing patients with intra-abdominal infection were prepared by an Expert Panel of the Surgical Infection Society and the Infectious Diseases Society of America. These updated guidelines replace those previously published in 2002 and 2003. The guidelines are intended for treating patients who either have these infections or may be at risk for them. New information, based on publications from the period 2003–2008, is incorporated into this guideline document. The panel has also added recommendations for managing intra-abdominal infection in children, particularly where such management differs from that of adults; for appendicitis in patients of all ages; and for necrotizing enterocolitis in neonates.

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.

Prognostic factors in critically ill patients suffering from secondary peritonitis: a retrospective, observational, survival time analysis

BACKGROUND

Acute mortality of unselected critically ill patients has improved during the last 15 years. Whether these benefits also affect survival of critically ill patients with secondary peritonitis is unclear as is the relevance of specific prognostic factors, such as source control.

METHODS

We performed a retrospective analysis of data collected prospectively from March 1993 to February 2005. A cohort of 319 consecutive postoperative patients with secondary peritonitis requiring intensive care was evaluated. End points for outcome analysis were derived from daily changes of hazard rate.

RESULTS

Four-month survival rate after intensive care unit (ICU) admission was 31.7%. For patients who have survived for more than 4 months, the 1-year survival was 82.7%. After adjustment for relevant covariates, a high disease severity at ICU admission and during ICU stay, specific comorbidities (extended malignancies, liver cirrhosis) and sources of infection (distal esophagus, stomach), and an inadequate initial antibiotic therapy were associated with worse 4-month prognosis. Inability to obtain source control was the most important determinant of mortality, and treatment after 2002 was combined with improved prognosis.

CONCLUSIONS

Four-month prognosis of critically ill, surgical patients with secondary peritonitis is poor and mostly determined by the ability to obtain source control. Outcome has improved since 2002, and after successful surgical and intensive care therapy long-term survival seems to be good.

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.

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

OBJECTIVES

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Review of the guidelines for complicated skin and soft tissue infections and intra-abdominal infections--are they applicable today?

Difficult-to-treat infections in surgical patients, such as serious skin and soft tissue infections (SSTIs) and complicated intra-abdominal infections (cIAIs), are the cause of significant morbidity and mortality, and carry an economic burden. These surgical site infections are typically polymicrobial infections caused by a plethora of pathogens, which include difficult-to-treat organisms and multiresistant Gram-positive and Gram-negative strains. Optimal management of SSTIs and cIAIs must take into account the presence of resistant pathogens, and depends on the administration of appropriate antimicrobial therapy (i.e. the correct spectrum, route and dose in a timely fashion for a sufficient duration as well as the timely implementation of source control measures). Treatment recommendations from the Infectious Diseases Society of America and the Surgical Infection Society are available for guidance in the management of both of these infections, yet the increased global prevalence of multidrug-resistant pathogens has complicated the antibiotic selection process. Several pathogens of concern include methicillin-resistant Staphylococcus aureus, responsible for problematic postoperative infections, especially in patients with SSTIs, extended-spectrum beta-lactamase-producing Gram-negative bacteria, including CTX-M-type-producing Escherichia coli strains, and multidrug-resistant strains of Bacteroides fragilis. New empirical regimens, taking advantage of potent broad-spectrum antibiotic options, may be needed for the treatment of certain high-risk patients with surgical site infections.

Economic consequences of failure of initial antibiotic therapy in hospitalized adults with complicated intra-abdominal infections

BACKGROUND

Initial antibiotic therapy in hospitalized adults with complicated intra-abdominal infection (cIAI) usually is empiric. We explored the economic consequences of failure of such therapy in this patient population.

METHODS

Using a large U.S. multi-institutional database, we identified all hospitalized adults admitted between April 1, 2003, and March 31, 2004; who had any cIAI; underwent laparotomy, laparoscopy, or percutaneous drainage of an intra-abdominal abscess ("surgery"); and received intravenous (IV) antibiotics. Initial therapy was characterized in terms of all IV antibiotics received, on the day of or one day before initial surgery. Antibiotic failure was designated on the basis of the need for reoperation or receipt of other IV antibiotics postoperatively. Switches to narrower spectrum agents and changes in regimen prior to discharge with no other evidence of clinical failure were not counted as antibiotic failures. Using multivariable linear regression, duration of IV antibiotic therapy, hospital length of stay, and total inpatient charges were compared between patients who did and did not fail initial therapy. Mortality was compared using multivariable logistic regression.

RESULTS

Among 6,056 patients who met the study entrance criteria, 22.4% failed initial antibiotic therapy. Patients who failed received an additional 5.6 days of IV antibiotic therapy (10.4 total days [95% confidence interval 10.1, 10.8] days vs. 4.8 total days [4.8, 4.9] for those not failing), were hospitalized an additional 4.6 days (11.6 total days [11.3, 11.9] vs. 6.9 total days [6.8, 7.0], respectively), and incurred $6,368 in additional inpatient charges ($16,520 [$16,131, $16,919] vs. $10,152 [$10,027, $10,280]) (all, p < 0.01). They also were more likely to die in the hospital (9.5% vs. 1.3%; multivariable odds ratio 3.58 [95% confidence interval 2.53, 5.06]).

CONCLUSIONS

Failure of initial IV antibiotic therapy in hospitalized adults with cIAIs is associated with longer hospitalization, higher hospital charges, and a higher mortality rate.

Progress in medical management of intra-abdominal infection

PURPOSE OF REVIEW

Intra-abdominal infection management remains debated and evidence-based recommendations are often lacking despite numerous studies. These controversies are mainly explained by the limited number of powered and well designed randomized controlled trials. This review focuses on recent studies on antibiotic therapy for intra-abdominal infections and in particular for the management of severe acute pancreatitis.

RECENT FINDINGS

For community-acquired intra-abdominal infection, early source control and antibiotic selection are well codified. In severe forms, every hour of delay between shock and antibiotherapy initiation reduces hospital survival. Antibiotics dose adjustment and continuous intravenous administration are suggested in critically ill patients and for difficult-to-treat pathogens. Shorter antibiotic treatment duration seems to offer similar clinical cure rates compared with prolonged therapy and could reduce emergence of resistance. For multidrug-resistant bacteria, the newly developed agents indications need to be better defined. In severe acute pancreatitis, antibiotic prophylaxis does not prevent necrosis infection nor does it reduce surgery requirement or mortality. Antibiotics should be given on demand. Infectious complications in pancreatitis are not reduced by probiotic prophylaxis and mortality is increased.

SUMMARY

There is a growing evidence to support early, dose-adjusted, antimicrobial therapy in severe intra-abdominal infection, together with shorter treatment duration if source control is achieved. This could reduce emergence of resistance without affecting clinical cure rates. In severe acute necrotizing pancreatitis, antibiotic and probiotic prophylaxis to reduce infection or mortality should be avoided.

Potent in vitro activity of tomopenem (CS-023) against methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa

Tomopenem (formerly CS-023) is a novel 1beta-methylcarbapenem with broad-spectrum coverage of gram-positive and gram-negative pathogens. Its antibacterial activity against European clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa was compared with those of imipenem and meropenem. The MICs of tomopenem against MRSA and P. aeruginosa at which 90% of the isolates tested were inhibited were 8 and 4 microg/ml, respectively, and were equal to or more than fourfold lower than those of imipenem and meropenem. The antibacterial activity of tomopenem against MRSA was correlated with a higher affinity for the penicillin-binding protein (PBP) 2a. Its activity against laboratory mutants of P. aeruginosa with (i) overproduction of chromosomally coded AmpC beta-lactamase; (ii) overproduction of the multidrug efflux pumps MexAB-OprM, MexCD-OprJ, and MexEF-OprN; (iii) deficiency in OprD; and (iv) various combinations of AmpC overproduction, MexAB-OprM overproduction, and OprD deficiency were tested. The increases in the MIC of tomopenem against each single mutant compared with that against its parent strain were within a fourfold range. Tomopenem exhibited antibacterial activity against all mutants, with an observed MIC range of 0.5 to 8 microg/ml. These results suggest that the antibacterial activity of tomopenem against the clinical isolates of MRSA and P. aeruginosa should be ascribed to its high affinity for PBP 2a and its activity against the mutants of P. aeruginosa, respectively.

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.

Empiric therapy for secondary peritonitis: a pharmacodynamic analysis of cefepime, ceftazidime, ceftriaxone, imipenem, levofloxacin, piperacillin/tazobactam, and tigecycline using Monte Carlo simulation

BACKGROUND

Inappropriate antibiotic therapy (ie, the selection of an empiric agent without activity against the responsible pathogen) of secondary peritonitis may result in poor patient outcomes. The selection of an appropriate agent can be challenging because of the emerging resistance of target organisms to commonly prescribed antibiotics.

OBJECTIVE

The aim of this study was to perform a pharmacodynamic analysis, using recent global surveillance data, of commonly prescribed antibiotic agents and a newer agent, tigecycline, indicated in 2005 for the treatment of complicated intra-abdominal infections, to determine their probability for achieving microbiologic success against aerobic bacteria associated with secondary peritonitis.

METHODS

A 2-compartment model was constructed using pharmacokinetic data from critically ill patients and global surveillance data on MIC distributions for microorganisms encountered in secondary peritonitis. A Monte Carlo simulation of the modeled data was performed to determine drug-appropriate pharmacodynamic end points, including free-drug time above the MIC, steady-state concentration above the MIC, and AUC/MIC ratios. A cumulative fraction of response (CFR) against aerobic bacteria involved in secondary peritonitis was calculated for cefepime, ceftazidime, ceftriaxone, imipenem, levofloxacin, pip eracillin/tazobactam, and tigecycline. A CFR > or =90% was considered microbiologic success. The following treatment regimens, administered as 30-minute N infusions, were examined: cefepime 1 and 2 g q12h, ceftazidime 1 and 2 g q8h, ceftriaxone 1 and 2 g q24h, imipenem 500 mg q6h, levofloxacin 750 mg q24h, pip eracillin/tazobactam 3.375 g q6h, and tigecycline 50 mg q12h, after a loading dose of 100 mg.

RESULTS

A CFR > or =90% against nonenterococcal bacteria was predicted for imipenem 500 mg q6h (96.8%), cefepime 2 and 1 g q12h (95.3% and 92.4%, respectively), ceftazidime 2 g q8h (94.2%), and piperacillin/tazobactam 3.375 g q6h (91.2%). A CFR of 84.5% was predicted for tigecycline 50 mg q12h. Ceftriaxone and levofloxacin were predicted to have a CFR <80%. When enterococci were included in the model, the predicted CFRs for imipenem, piperacillin/tazobactam, and tigecycline were 93.4%, 88.4%, and 86.7%, respectively.

CONCLUSIONS

: MIC distribution and pathogen prevalence strongly influence the likelihood of microbiological success in secondary peritonitis; therefore, decisions regarding empiric therapy should consider local epidemiology. Using current global data, the following regimens are adequate choices if Enterococcus is not targeted: Combination therapy (with metronidazole) using cefepime 1 g or 2 g q12h, or ceftazidime 2 g q8h; or monotherapy with imipenem 500 mg q6h or piperacillin-tazobactam 3.375 g q6h. When Enterococcus is included in the epidemiologic mix, imipenem, piperacillin/tazobactam, and tigecycline all appear to be viable monotherapeutic choices.

Intra-abdominal infections

PURPOSE OF REVIEW

The aim of this article is to outline developments in the three cornerstones of treatment of intra-abdominal infections during critical illness: source control; antimicrobial therapy; and mitigation of deranged immune and coagulation responses.

RECENT FINDINGS

Although adequate source control remains the goal of mechanical management of intra-abdominal infections, neither planned re-laparotomy nor open-abdomen management appears to offer a survival benefit as compared with on-demand re-laparotomy. Novel approaches to restoration of a functional gastrointestinal tract have emerged as alternatives to more invasive surgery. A persistent increase in the prevalence of intra-abdominal infections caused by multidrug resistant pathogens has led researchers to investigate shorter-course antimicrobial therapy and other antibiotic administration strategies with encouraging initial results. Therapy with recombinant human activated protein C should now be considered for patients with severe abdominal sepsis associated with a high risk of death.

SUMMARY

Because randomized controlled trials of intra-abdominal infections involve critically ill patients infrequently, only limited evidence-based recommendations regarding the management of these patients may be drawn. Therapy should focus above all else on timely obtainment of adequate source control, in conjunction with judicious use of antimicrobial therapy dictated by individual patient risk factors for infection with multidrug resistant pathogens.

Tigecycline is efficacious in the treatment of complicated intra-abdominal infections

BACKGROUND

Empiric treatment of complicated intra-abdominal infections (cIAI) represents a clinical challenge because of the diverse bacteriology and the emergence of bacterial resistance. The efficacy and safety of tigecycline (TGC), a first-in-class, expanded broad-spectrum glycylcycline antibiotic, were compared with imipenem/cilastatin (IMI/CIS) in patients with cIAI.

METHODS

In this prospective, double-blind, phase 3, multinational trial, patients were randomly assigned to intravenous (i.v.) TGC (100 mg initial dose, then 50 mg every 12 h) or i.v. IMI/CIS (500/500 mg every 6 h) for 5-14 days. Clinical response was assessed at the test-of-cure (TOC) visit (14-35 days after therapy) for microbiologically evaluable (ME) and microbiologically modified intent-to-treat (m-mITT) populations (co-primary efficacy endpoint populations in which cure/failure response rates were determined).

RESULTS

Of 817 mITT patients (i.e., received > or = 1 dose of study drug), 641 (78%) comprised the m-mITT cohort (322 TGC, 319 IMI/CIS) and 523 (64%) were ME (266 TGC, 256 IMI/CIS). Patients were predominantly white (88%) and male (59%) with a mean age of 49 years. The primary diagnoses for the mITT group were complicated appendicitis (41%), cholecystitis (22%), and intra-abdominal abscess (11%). For the ME population, clinical cure rates at TOC were 91.3% (242/265) for TGC versus 89.9% (232/258) for IMI/CIS (95% CI -4.0, 6.8; P<0.001). Corresponding clinical cure rates within the m-mITT population were 86.6% (279/322) for TGC versus 84.6% (270/319) for IMI/CIS (95% CI -3.7, 7.5; P<0.001 for noninferiority TGC versus IMI/CIS). The most commonly reported adverse events for TGC and IMI/CIS were nausea (17.6% TGC versus 13.3% IMI/CIS; P=0.100) and vomiting (12.6% TGC versus 9.2% IMI/CIS; P=0.144).

CONCLUSIONS

TGC is efficacious in the treatment of patients with cIAIs and TGC met per the protocol-specified statistical criteria for noninferiority to the comparator, IMI/CIS.

Predictors of efficacy and health resource utilization in treatment of complicated intra-abdominal infections: evidence for pooled clinical studies comparing tigecycline with imipenem-cilastatin

BACKGROUND

Duration of intravenous (IV) treatment, surgical/radiologic interventions for infection control, and hospital length of stay (LOS) are important cost considerations in complicated intra-abdominal infections (cIAIs).

METHODS

Data were pooled from two multinational, double-blind studies conducted in hospitalized adults with cIAIs who were randomized (1:1) to receive tigecycline (100 mg IV initial dose then 50 mg IV every 12 h) or imipenem-cilastatin (500 mg IV every 6 h) for 5 to 14 days in order to assess tigecycline safety and efficacy. This report focuses on developing predictors of cure and health care resource utilization, including the need for repeat surgical/radiologic interventions, duration of IV antibiotic therapy, and hospital LOS. Multiple regression models were applied for each of the above outcomes, incorporating both baseline and on-treatment potential covariates. Logistic modeling was used for categorical outcomes (cure; repeat surgical/radiologic interventions) and least squares modeling for continuous outcomes (duration of IV antibiotic therapy; LOS). Stepwise selection was used to retain only those predictors found to be significant (p < 0.05) independent risk factors.

RESULTS

The most common causative pathogen was Escherichia coli (63.0%), with 63.3% of the patients exhibiting polymicrobial infections. The most common cIAI diagnosis was complicated appendicitis (51.9%). Lack of clinical cure (+ 6.1 days; p < 0.0001), perforation of the intestine (+3.7 days; p < 0.0001), an Acute Physiology and Chronic Health Evaluation (APACHE) score >15 (+3.1 days; p=0.039), abnormal plasma sodium concentration (+3.7 days; p=0.026), and repeat surgical/radiologic intervention (+2.2 days; p=0.0097) were identified as key risk factors for longer LOS. Inadequate source control was associated with reduced odds of cure, longer IV treatment duration (+1.5 days; p=0.007), and longer LOS. The treatment groups did not differ in terms of LOS, IV treatment duration, or clinical cure.

CONCLUSION

Tigecycline was similar to imipenem-cilastatin in terms of both efficacy and health resource utilization. Risk factors identified in this study for both outcome measures are offered as support for guiding clinical practice.

Intra-abdominal infections: considerations for the use of the carbapenems

Intra-abdominal infection remains a common and frequently severe medical condition, carrying with it significant morbidity and mortality. These infections are almost always polymicrobial in nature as they are caused by mixed aerobic/anaerobic intestinal flora. Despite substantial improvements in both the medical and surgical management of these infections over the last several decades, there remains an opportunity to further enhance the utilization of adjunctive antibiotic therapy. As a result of the epidemiology and the current resistance profile of the infecting pathogens, the carbapenems represent a class of antibiotics that are considered appropriate for the treatment of severe intra-abdominal infections. This review will discuss the classification and microbiology of these infections and emerging resistance in the pathogens of interest. The review also and focuses on the role of the carbapenems in the management of the constellation of diseases known as intra-abdominal infection.

Impact of inactive empiric antimicrobial therapy on inpatient mortality and length of stay

The consequences of inactive empiric antimicrobial therapy are not well-described and may cause prolonged hospitalization or infection-related mortality. In vitro susceptibility results for 884 patients hospitalized at an academic medical center with gram-negative bloodstream infections (GNBI) from 2001 to 2003 were matched to antimicrobial orders within 24 h of culture. Clinical characteristics, organism, inpatient mortality, and length of stay after culture for patients with GNBI were compared between patients receiving active versus inactive empiric antimicrobial therapy. A total of 14.1% of patients with GNBI received inactive empiric therapy, defined as no antimicrobial therapy within 24 h of the culture active against the identified organism based on in vitro microbiology reports. Patients who received inactive therapy were more likely to be younger, to be infected with Pseudomonas aeruginosa, to have a nosocomial infection, and to receive antimicrobial monotherapy but less likely to be bacteremic with Escherichia coli or to have sepsis (P < 0.05). There were no significant differences in mortality between patients receiving active versus inactive empiric therapy (16.1% versus 13.6%, respectively) or in length of stay after positive culture (11.5 days versus 12.6 days, respectively). Only 45 patients had greater than 2 days of exposure to inactive therapy; however, 8/30 patients (26.7%) who never received active antimicrobial therapy died while in the hospital. Inactive empiric therapy was more common in healthier patients. Inactive antimicrobial therapy in the first 24 h did not significantly impact average outcomes for GNBI among hospitalized patients but may have caused harm to specific individuals.

Tigecycline: a new glycylcycline antimicrobial

Tigecycline is a new glycyclcycline antimicrobial recently approved for use in the USA, Europe and elsewhere. While related to the tetracyclines, tigecycline overcomes many of the mechanisms responsible for resistance to this class. It demonstrates favourable in vitro potency against a variety of aerobic and anaerobic Gram-positive and Gram-negative pathogens, including those frequently demonstrating resistance to multiple classes of antimicrobials. This includes methicillin-resistant Staphylococcus aureus, penicillin-resistant S. pneumoniae, vancomycin-resistant enterococci, Acinetobacter baumannii, beta-lactamase producing strains of Haemophilis influenzae and Moraxella catarrhalis, and extended-spectrum beta-lactamase producing strains of Escherichia coli and Klebsiella pneumoniae. In contrast, minimum inhibitory concentrations for Pseudomonas and Proteus spp. are markedly elevated. Tigecycline is administered parenterally twice daily. Randomised, controlled trials have demonstrated that tigecycline is non-inferior to the comparators for the treatment of complicated skin and skin structure infections, as well as complicated intra-abdominal infections. The most frequent and problematic side effect associated with its administration to date has been nausea and/or vomiting.