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

The effect of damage control laparotomy on surgical-site infection risks after emergent intestinal surgery

INTRODUCTION

Damage-control laparotomy has been widely used in general surgery. However, associated surgical-site infection risks have rarely been investigated. Damage-control laparotomy allows for additional opportunities for decontamination. We hypothesized that damage-control laparotomy would be associated with lower surgical-site infection risks compared with laparotomy with only primary fascial closure or with primary fascial and skin closure.

METHODS

Patients admitted for emergent intestinal surgery from 2006 to 2021 were included. Multivariate analyses were performed to identify surgical-site infection-associated risk factors. Although variables like laparotomy type (damage-control laparotomy, primary fascial closure, and primary fascial and skin closure) were provided by National Surgical Quality Improvement Program, other variables such as number of operations were retrospectively collected. P < .05 was considered significant.

RESULTS

Overall, 906 patients were included; 213 underwent damage-control laparotomy, 175 primary fascial closure, and 518 primary fascial and skin closure. Superficial, deep, and organ-space surgical-site infection developed in 66, 6, and 97 patients, respectively. Compared with primary fascial and skin closure, both damage-control laparotomy (odds ratio, 0.30 [95% CI, 0.13-0.73], P = .008) and primary fascial closure (odds ratio, 0.09 [95% CI, 0.02-0.37], P = .001) were associated with lower superficial incisional surgical-site infection but not organ-space surgical-site infection risk (odds ratio, 0.80 [95% CI, 0.29-2.19] P = .667 and odds ratio, 0.674 [95% CI, 0.21-2.14], P = .502, respectively). Body mass index was associated with increased risk of superficial incisional surgical-site infection (odds ratio, 1.06 [95% CI, 1.03-1.09], P < .001) whereas frailty was associated with organ space surgical-site infection (odds ratio, 3.28 [95% CI, 1.29-8.36], P = .013). For patients who underwent damage-control laparotomy, the number of operations did not affect risk of either superficial incisional surgical-site infection or organ space SSI.

CONCLUSION

Herein, compared with primary fascial and skin closure, both damage-control laparotomy and primary fascial closure were associated with lower superficial but not organ space surgical-site infection risks. For patients who underwent damage-control laparotomy, number of operations did not affect surgical-site infection risks.

Exploration of a Potential Desirability of Outcome Ranking Endpoint for Complicated Intra-Abdominal Infections Using 9 Registrational Trials for Antibacterial Drugs

BACKGROUND

Desirability of outcome ranking (DOOR) is a novel approach to clinical trial design that incorporates safety and efficacy assessments into an ordinal ranking system to evaluate overall outcomes of clinical trial participants. Here, we derived and applied a disease-specific DOOR endpoint to registrational trials for complicated intra-abdominal infection (cIAI).

METHODS

Initially, we applied an a priori DOOR prototype to electronic patient-level data from 9 phase 3 noninferiority trials for cIAI submitted to the US Food and Drug Administration between 2005 and 2019. We derived a cIAI-specific DOOR endpoint based on clinically meaningful events that trial participants experienced. Next, we applied the cIAI-specific DOOR endpoint to the same datasets and, for each trial, estimated the probability that a participant assigned to the study treatment would have a more desirable DOOR or component outcome than if assigned to the comparator.

RESULTS

Three key findings informed the cIAI-specific DOOR endpoint: (1) a significant proportion of participants underwent additional surgical procedures related to their baseline infection; (2) infectious complications of cIAI were diverse; and (3) participants with worse outcomes experienced more infectious complications, more serious adverse events, and underwent more procedures. DOOR distributions between treatment arms were similar in all trials. DOOR probability estimates ranged from 47.4% to 50.3% and were not significantly different. Component analyses depicted risk-benefit assessments of study treatment versus comparator.

CONCLUSIONS

We designed and evaluated a potential DOOR endpoint for cIAI trials to further characterize overall clinical experiences of participants. Similar data-driven approaches can be utilized to create other infectious disease-specific DOOR endpoints.

Effect of Antibiotic Duration in Emergency General Surgery Patients with Intra-Abdominal Infection Managed with Open vs Closed Abdomen

BACKGROUND

Data on duration of antibiotics in patients managed with an open abdomen (OA) due to intra-abdominal infection (IAI) are scarce. We hypothesized that patients with IAI managed with OA rather than closed abdomen (CA) would have higher rates of secondary infections (SIs) independent of the duration of the antibiotic treatment.

METHODS

This was an observational, prospective, multicenter, international study of patients with IAI requiring laparotomy for source control. Demographic and antibiotic duration values were collected. Primary outcomes were SI (surgical site, bloodstream, pneumonia, urinary tract) and mortality. Statistical analysis included ANOVA, chi-square/Fisher's exact test, and logistic regression.

RESULTS

Twenty-one centers contributed 752 patients. The average age was 59.6 years, 43.6% were women, and 43.9% were managed with OA. Overall mortality was 16.1%, with higher rates among OA patients (31.6% vs 4.4%, p < 0.001). OA patients had higher Sequential Organ Failure Assessment (4.7 vs 1.8, p < 0.001), American Society of Anesthesiologists Physical Status (3.6 vs 2.7, p < 0.001), and APACHE II scores (16.1 vs 9.4, p < 0.001). The mean duration of antibiotics was 6.5 days (8.0 OA vs 5.4 CA, p < 0.001). A total of 179 (23.8%) patients developed SI (33.1% OA vs 16.8% CA, p < 0.001). Longer antibiotic duration was associated with increased rates of SI: 1 to 2 days, 15.8%; 3 to 5 days, 20.4%; 6 to 14 days, 26.6%; and more than 14 days, 46.8% (p < 0.001).

CONCLUSIONS

Patients with IAI managed with OA had higher rates of SI and increased mortality compared with CA. A prolonged duration of antibiotics was associated with increased rates of SI. Increased antibiotic duration is not associated with improved outcomes in patients with IAI and OA.

IFN-β Improves Sepsis-related Alveolar Macrophage Dysfunction and Postseptic Acute Respiratory Distress Syndrome-related Mortality

IFN-β is reported to improve survival in patients with acute respiratory distress syndrome (ARDS), possibly by preventing sepsis-induced immunosuppression, but its therapeutic nature in ARDS pathogenesis is poorly understood. We investigated the therapeutic effects of IFN-β for postseptic ARDS to better understand its pathogenesis in mice. Postseptic ARDS was reproduced in mice by cecal ligation and puncture to induce sepsis, followed 4 days later by intratracheal instillation of Pseudomonas aeruginosa to cause pneumonia with or without subcutaneous administration of IFN-β 1 day earlier. Sepsis induced prolonged increases in alveolar TNF-α and IL-10 concentrations and innate immune reprogramming; specifically, it reduced alveolar macrophage (AM) phagocytosis and KC (CXCL1) secretion. Ex vivo AM exposure to TNF-α or IL-10 duplicated cytokine release impairment. Compared with sepsis or pneumonia alone, pneumonia after sepsis was associated with blunted alveolar KC responses and reduced neutrophil recruitment into alveoli despite increased neutrophil burden in lungs (i.e., "incomplete alveolar neutrophil recruitment"), reduced bacterial clearance, increased lung injury, and markedly increased mortality. Importantly, IFN-β reversed the TNF-α/IL-10-mediated impairment of AM cytokine secretion in vitro, restored alveolar innate immune responsiveness in vivo, improved alveolar neutrophil recruitment and bacterial clearance, and consequently reduced the odds ratio for 7-day mortality by 85% (odds ratio, 0.15; 95% confidence interval, 0.03-0.82; P = 0.045). This mouse model of sequential sepsis → pneumonia infection revealed incomplete alveolar neutrophil recruitment as a novel pathogenic mechanism for postseptic ARDS, and systemic IFN-β improved survival by restoring the impaired function of AMs, mainly by recruiting neutrophils to alveoli.

Th17 cells are associated with protection from ventilator associated pneumonia

BACKGROUND

CD4+ T-helper 17 (Th17) cells and Interleukin (IL)-17A play an important role in clearing pathogens in mouse models of pneumonia. We hypothesized that numbers of Th17 cells and levels of IL-17A are associated with risk for nosocomial pneumonia in humans.

METHODS

We collected bronchoalveolar lavage (BAL) fluid from mechanically ventilated (n = 25) patients undergoing quantitative bacterial culture to evaluate for ventilator associated pneumonia (VAP). We identified Th17 cells by positive selection of CD4+ cells, stimulation with ionomycin and PMA, then staining for CD4, CD45, CCR6, IL-17A, and IFN-γ followed by flow cytometric analysis (n = 21). We measured inflammatory cytokine levels, including IL-17A, in BAL fluid by immunoassay.

RESULTS

VAP was detected in 13 of the 25 subjects. We identified a decreased percentage of IL-17A producing Th17 cells in BAL fluid from patients with VAP compared to those without (p = 0.02). However, we found no significant difference in levels of IL-17A in patients with VAP compared to those without (p = 0.07). Interestingly, IL-17A levels did not correlate with Th17 cell numbers. IL-17A levels did show strong positive correlations with alveolar neutrophil numbers and total protein levels.

CONCLUSIONS

Th17 cells are found at lower percentages in BAL fluid from mechanically ventilated patients with VAP and IL-17A levels correlated with Th17 cell percentages in non-VAP subjects, but not those with VAP. These findings suggest that Th17 cells may be protective against development of nosocomial pneumonia in patients receiving mechanical ventilation and that alveolar IL-17A in VAP may be derived from sources other than alveolar Th17 cells.

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.

Do Polymicrobial Intra-Abdominal Infections Have Worse Outcomes than Monomicrobial Intra-Abdominal Infections?

BACKGROUND

Numerous studies have demonstrated microorganism interaction through signaling molecules, some of which are recognized by other bacterial species. This interspecies synergy can prove detrimental to the human host in polymicrobial infections. We hypothesized that polymicrobial intra-abdominal infections (IAI) have worse outcomes than monomicrobial infections.

METHODS

Data from the Study to Optimize Peritoneal Infection Therapy (STOP-IT), a prospective, multicenter, randomized controlled trial, were reviewed for all occurrences of IAI having culture results available. Patients in STOP-IT had been randomized to receive four days of antibiotics vs. antibiotics until two days after clinical symptom resolution. Patients with polymicrobial and monomicrobial infections were compared by univariable analysis using the Wilcoxon rank sum, χ(2), and Fisher exact tests.

RESULTS

Culture results were available for 336 of 518 patients (65%). The durations of antibiotic therapy in polymicrobial (n = 225) and monomicrobial IAI (n = 111) were equal (p = 0.78). Univariable analysis demonstrated similar demographics in the two populations. The 37 patients (11%) with inflammatory bowel disease were more likely to have polymicrobial IAI (p = 0.05). Polymicrobial infections were not associated with a higher risk of surgical site infection, recurrent IAI, or death.

CONCLUSION

Contrary to our hypothesis, polymicrobial IAI do not have worse outcomes than monomicrobial infections. These results suggest polymicrobial IAI can be treated the same as monomicrobial IAI.

Susceptibility of gram-negative aerobic bacilli from intra-abdominal pathogens to antimicrobial agents collected in the United States during 2011

OBJECTIVES

During 2011, a total of 1442 gram-negative pathogens from intra-abdominal infections were collected as part of the Study for Monitoring Antimicrobial Resistance Trends (SMART) from 19 hospital sites within the United States. Susceptibility to ertapenem and comparators and molecular analysis of ertapenem resistant isolates was performed.

METHODS

Extended-spectrum beta-lactamase ESBL (ESBL) isolates were determined using the Clinical and Laboratory Standards Institute's recommended phenotypic test. Isolates were identified to the species level, and tested for antimicrobial susceptibility using custom MicroScan dehydrated broth microdilution panels ESBLs and carbapenemases were characterized using the Check-Points microarray. Strain typing of Klebsiella pneumoniae was performed by rep-PCR on the DiversiLab System.

RESULTS

The majority of isolates were Escherichia coli (36%), K. pneumoniae (18.6%), Pseudomonas aeruginosa (12.1%) and Enterobacter cloacae (8.4%). Incidence of ESBL-positive isolates was 12.7%, 9.7%, 3.6% and 3.1% for K. pneumoniae, E. coli, Proteus mirabilis and Klebsiella oxytoca, respectively. Against the majority of isolates and species tested, the most active antibiotics were amikacin, ertapenem, and imipenem, with the carbapenems being the most active in vitro, including against ESBL-positive isolates of E. coli. All other antibiotics exhibited diminished activity. Against K. pneumoniae, the carbapenems were notably less active against ESBL-positive isolates though their activity against this sub-population was still the highest of all antibiotics tested; however, 41.1% (14 of 34) of the phenotypically ESBL-positive K. pneumoniae co-produced a carbapenemase (KPC2 or KPC3), and >90% of the isolates producing only an ESBL remained susceptible to ertapenem.

CONCLUSIONS

Further monitoring of susceptibility of intra-abdominal isolates is warranted due to limited therapeutic options available to physicians.

TLR3 agonist improves survival to secondary pneumonia in a double injury model

BACKGROUND

Toll-like receptors (TLR) can initiate various immune responses and are therefore activated under diverse infectious states. Previous studies have focused on TLR3 primarily as an antiviral pathway. However, recent research has demonstrated its efficacy in bacterial infection. Having developed a murine double injury model of cecal ligation and puncture (CLP) followed by Pseudomonas aeruginosa (Pa), we hypothesized that targeted administration of Poly I:C, a TLR3 agonist, would protect mice against secondary pneumonia.

MATERIAL AND METHODS

B6 mice underwent CLP followed 4 d afterward by an intranasal dose of Pa. Animals were given Poly I:C or vehicle (phosphate-buffered saline) intranasally 24 h post CLP and every day thereafter for a total of 6 d. For acute studies, mice were sacrificed at two time points, 4 d post CLP and 1 d post pneumonia (Pa).

RESULTS

Poly I:C treatment led to a significant improvement in survival (69% versus 33%). Cytokine analysis from bronchioalveolar lavage displayed significant differences both immediately before and after pneumonia. Bronchioalveolar lavage cultures taken at 24 h post double injury showed significantly higher colony counts in the lungs of control animals compared with those of Poly I:C animals. Measurements of TLR3 expression showed significant increases within both the immune and lung epithelial cells of Poly I:C-treated mice. Finally, the lungs of treated animals had significant increases in lymphocytes and innate cells.

CONCLUSIONS

The prophylactic treatment applied in this clinically relevant model further illustrates the overarching hypothesis of immune dysfunction and the possibility of corrective immune modulation within the setting of sepsis.

Period of irreversible therapeutic intervention during sepsis correlates with phase of innate immune dysfunction

Sepsis is a major health problem in the United States with high incidence and elevated patient care cost. Using an animal model of sepsis, cecum ligation, and puncture, we observed that mice became rapidly hypothermic reaching a threshold temperature of 28 °C within 5-10 h after initiation of the insult, resulting in a reliable predictor of mortality, which occurred within 30-72 h of the initial procedure. We also observed that the inflammatory gene expression in lung and liver developed early within 1-2 h of the insult, reaching maximum levels at 6 h, followed by a decline, approaching basal conditions within 20 h. This decrease in inflammatory gene expression at 20 h after cecal ligation and puncture was not due to resolution of the insult but rather was an immune dysfunction stage that was demonstrated by the inability of the animal to respond to a secondary external inflammatory stimulus. Removal of the injury source, ligated cecum, within 6 h of the initial insult resulted in increased survival, but not after 20 h of cecal ligation and puncture. We concluded that the therapeutic window for resolving sepsis is early after the initial insult and coincides with a stage of hyperinflammation that is followed by a condition of innate immune dysfunction in which reversion of the outcome is no longer possible.

Myeloid-derived suppressor cells evolve during sepsis and can enhance or attenuate the systemic inflammatory response

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous Gr1(+) CD11b(+) population of immature cells containing granulocytic and monocytic progenitors, which expand under nearly all inflammatory conditions and are potent repressors of T-cell responses. Studies of MDSCs during inflammatory responses, including sepsis, suggest they can protect or injure. Here, we investigated MDSCs during early and late sepsis. To do this, we used our published murine model of cecal ligation and puncture (CLP)-induced polymicrobial sepsis, which transitions from an early proinflammatory phase to a late anti-inflammatory and immunosuppressive phase. We confirmed that Gr1(+) CD11b(+) MDSCs gradually increase after CLP, reaching ∼88% of the bone marrow myeloid series in late sepsis. Adoptive transfer of early (day 3) MDSCs from septic mice into naive mice after CLP increased proinflammatory cytokine production, decreased peritoneal bacterial growth, and increased early mortality. Conversely, transfer of late (day 12) MDSCs from septic mice had the opposite effects. Early and late MDSCs studied ex vivo also differed in their inflammatory phenotypes. Early MDSCs expressed nitric oxide and proinflammatory cytokines, whereas late MDSCs expressed arginase activity and anti-inflammatory interleukin 10 (IL-10) and transforming growth factor β (TGF-β). Late MDSCs had more immature CD31(+) myeloid progenitors and, when treated ex vivo with granulocyte-macrophage colony-stimulating factor (GM-CSF), generated fewer macrophages and dendritic cells than early MDSCs. We conclude that as the sepsis inflammatory process progresses, the heterogeneous MDSCs shift to a more immature state and from being proinflammatory to anti-inflammatory.

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.

Perioperative use of antibiotics in intra-abdominal surgical infections

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Infections of respiratory or abdominal origin in ICU patients: what are the differences?

INTRODUCTION

There are few data related to the effects of different sources of infection on outcome. We used the Sepsis Occurrence in Acutely ill Patients (SOAP) database to investigate differences in the impact of respiratory tract and abdominal sites of infection on organ failure and survival.

METHODS

The SOAP study was a cohort, multicenter, observational study which included data from all adult patients admitted to one of 198 participating intensive care units (ICUs) from 24 European countries during the study period. In this substudy, patients were divided into two groups depending on whether, on admission, they had abdominal infection but no respiratory infection or respiratory infection but no abdominal infection. The two groups were compared with respect to patient and infection-related characteristics, organ failure patterns, and outcomes.

RESULTS

Of the 3,147 patients in the SOAP database, 777 (25%) patients had sepsis on ICU admission; 162 (21%) had abdominal infection without concurrent respiratory infection and 380 (49%) had respiratory infection without concurrent abdominal infection. Age, sex, and severity scores were similar in the two groups. On admission, septic shock was more common in patients with abdominal infection (40.1% vs. 29.5%, P = 0.016) who were also more likely to have early coagulation failure (17.3% vs. 9.5%, P = 0.01) and acute renal failure (38.3% vs. 29.5%, P = 0.045). In contrast, patients with respiratory infection were more likely to have early neurological failure (30.5% vs. 9.9%, P < 0.001). The median length of ICU stay was the same in the two groups, but the median length of hospital stay was longer in patients with abdominal than in those with respiratory infection (27 vs. 20 days, P = 0.02). ICU (29%) and hospital (38%) mortality rates were identical in the two groups.

CONCLUSIONS

There are important differences in patient profiles related to the site of infection; however, mortality rates in these two groups of patients are identical.

Characterization and modulation of the immunosuppressive phase of sepsis

Sepsis continues to cause significant morbidity and mortality in critically ill patients. Studies of patients and animal models have revealed that changes in the immune response during sepsis play a decisive role in the outcome. Using a clinically relevant two-hit model of sepsis, i.e., cecal ligation and puncture (CLP) followed by the induction of Pseudomonas aeruginosa pneumonia, we characterized the host immune response. Second, AS101 [ammonium trichloro(dioxoethylene-o,o')tellurate], a compound that blocks interleukin 10 (IL-10), a key mediator of immunosuppression in sepsis, was tested for its ability to reverse immunoparalysis and improve survival. Mice subjected to pneumonia following CLP had different survival rates depending upon the timing of the secondary injury. Animals challenged with P. aeruginosa at 4 days post-CLP had approximately 40% survival, whereas animals challenged at 7 days had 85% survival. This improvement in survival was associated with decreased lymphocyte apoptosis, restoration of innate cell populations, increased proinflammatory cytokines, and restoration of gamma interferon (IFN-gamma) production by stimulated splenocytes. These animals also showed significantly less P. aeruginosa growth from blood and bronchoalveolar lavage fluid. Importantly, AS101 improved survival after secondary injury 4 days following CLP. This increased survival was associated with many of the same findings observed in the 7-day group, i.e., restoration of IFN-gamma production, increased proinflammatory cytokines, and decreased bacterial growth. Collectively, these studies demonstrate that immunosuppression following initial septic insult increases susceptibility to secondary infection. However, by 7 days post-CLP, the host's immune system has recovered sufficiently to mount an effective immune response. Modulation of the immunosuppressive phase of sepsis may aid in the development of new therapeutic strategies.

Mortality for intra-abdominal infection is associated with intrinsic risk factors rather than the source of infection

BACKGROUND

Intra-abdominal infections (IAIs) are an important cause of mortality and morbidity. Nosocomial IAIs (NIAIs) have been associated with higher mortality than community-acquired IAIs (CIAIs). We hypothesized that intrinsic risk factors were a better predictor of mortality than the type of infection.

METHODS

Patients with IAI treated at a single urban academic hospital over 8 years (June 1999-June 2007) were retrospectively reviewed. Data collected included demographics, comorbidities, source of infection, type of infection (community vs nosocomial), type of intervention (operation versus percutaneous drainage), and postoperative complications. Charlson Comorbidity Index and multiple organ dysfunction (MOD) scores were evaluated at admission and on postoperative day 7 (POD-7).

RESULTS

There were 452 patients; 234 (51.8%) had CIAI and 218 (48.2%) had NIAI. The mean age was 51.3 +/- 0.8. The most common source of CIAI was the appendix (n = 129, 28.5%); 137 patients with NIAI had postoperative infections (30.3%). When patients with appendicitis were excluded, there was no difference in mortality or complications between patients with CIAI and NIAI. Logistic regression analysis demonstrated catheter-related bloodstream infection (P < .001; OR 7.3, 95% CI, 2.5-22.2), cardiac event (P < .001; OR 6.0, 95% CI, 2.3-16.1), and age > or = 65 (P = .009; OR 3.8, 95% CI, 1.4-8.8) to be independent risk factors for mortality. Among patients who failed initial therapy, a non-appendiceal source of infection (P < .001; OR 4.7, 95% CI, 2.3-9.8) and a Charlson score > or =2 (P = .033; OR 1.6, 95% CI, 1.0-2.6) were determined to be independent risk factors. Non-appendiceal source of infection (P = .001, OR 3.3, 95% CI, 1.6-7.0) and POD-7 MOD score > or =4 (P < .001; OR 3.4, 95% CI, 1.9-6.0) were found to be independent predictors for re-intervention.

CONCLUSION

These results suggest mortality from IAI is strongly related to age and organ dysfunction; however, catheter-related bloodstream infection and postoperative cardiac events have a greater effect on outcome.

The use of carbapenems in the treatment of serious infections

Inadequate initial antimicrobial treatment in serious infections leads to increased mortality. Achieving adequate treatment is increasingly difficult because of the increasing prevalence of multidrug-resistant (MDR) pathogens. The carbapenems are potent, broad-spectrum antibiotics that have been shown to be safe and efficacious therapies in the treatment of serious infections. This review is intended to compare the 4 major members of the carbapenem class, which include imipenem, meropenem, ertapenem, and doripenem, with other widely used antimicrobial agents in the intensive care unit (ICU). The carbapenems are potent, broad-spectrum antibiotics that have been shown to be safe and efficacious therapies in the treatment of serious infections. They provide better gram-negative coverage than other beta-lactams and are stable against extended-spectrum beta-lactamases and AmpC beta-lactamases, making them effective in the treatment of many MDR bacteria. The newly approved carbapenem, doripenem, may help preserve the utility of the carbapenem class.

Inflammation and the host response to injury, a large-scale collaborative project: patient-oriented research core--standard operating procedures for clinical care VII--Guidelines for antibiotic administration in severely injured patients

When the clinical decision to treat a critically ill patient with antibiotics has been made, one must attempt to identify the site of infection based on clinical signs and symptoms, laboratory or diagnostic radiology studies. Identification of site requires, examination of patient, inspection of all wounds, chest radiograph, and calculation of clinical pulmonary infection score if ventilated, obtaining blood cultures, urinalysis, and line change if clinical suspicion of central venous catheter (CVC) source. If it is impossible to identify site, obtain cultures from all accessible suspected sites and initiate empiric, broad spectrum antibiotics. If likely site can be identified answer these questions: Is intra-abdominal site suspected? Is pulmonary source of infection suspected? Is skin, skin structure or soft tissue site suspected? If yes, does the patient have clinical signs suspicion for necrotizing soft tissue infection (NSTI)? Is a CVC infection suspected? Risk factors for more complicated infections are discussed and specific antibiotic recommendations are provided for each type and severity of clinical infection. Decision to continue, discontinue and/or alter antibiotic/antimicrobial treatment should be based on the clinical response to treatment, diagnostic or interventional findings, and culture and sensitivity data, bearing in mind that not all patients with infections will have positive cultures because of limitations of specimen handling, microbiology laboratory variations, time between specimen acquisition and culture, or presence of effective antibiotics at the time that specimens were obtained. It should also be noted that not all patients with increased temperature/WBC have an infection. Discontinuation of antibiotics is appropriate if cultures and other diagnostic studies are negative.

Building a continuous multicenter infection surveillance system in the intensive care unit: findings from the initial data set of 9,493 patients from 71 Italian intensive care units

OBJECTIVE

To describe the epidemiology of infections in intensive care units (ICUs), whether present at admission or acquired during the stay.

METHODS

Prospective data collection lasting 6 months in 71 Italian adult ICUs. Patients were screened for infections and risk factors at ICU admission and daily during their stay.

MAIN RESULTS

Out of 9,493 consecutive patients admitted to the 71 ICUs, 11.6% had a community-acquired infection, 7.4% a hospital-acquired infection, and 11.4% an ICU-acquired infection. The risk curve of acquiring infection in the ICU was higher in patients who entered without infection than in those already infected (log-rank test, p < .0001; at 15 days, 44.0% vs. 34.6%). Hospital mortality (27.8% overall) was higher in patients admitted with infection than in those who acquired infection in the ICU (45.0% vs. 32.4%, p < .0001). Although the presence of infection per se did not influence mortality, the conditions of severe sepsis and septic shock were strong prognostic factors (odds ratio, 2.3 and 4.8, respectively). Apart from ICU-acquired peritonitis, no other site of infection reached statistical significance as an independent prognostic factor for hospital mortality.

CONCLUSIONS

Adding specific data on infections and risk factors to a well-established electronic data collection system is a reliable basis for a continuous multicenter infection surveillance program in the ICU. Given the well-established importance of infection prevention programs, our data suggest that the improvement of the treatment of severe sepsis and septic shock is the key to lower infection-related mortality in the ICU. This calls for closer attention to severe infections in surveillance programs.

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.

International integrated database for the evaluation of severe sepsis and drotrecogin alfa (activated) therapy: analysis of efficacy and safety data in a large surgical cohort

BACKGROUND

The International Integrated Database for the Evaluation of Severe Sepsis and Drotrecogin alfa (activated) Therapy includes an extensive cohort of surgical patients (1659/4459; 37%). This database broadens the experience reported on a comparatively small set of surgical patients from the pivotal Protein C Worldwide Evaluation in Severe Sepsis trial to examine issues of safety and efficacy in a much larger cohort.

METHODS

We conducted a retrospective analysis of prospectively defined outcomes from 5 integrated clinical studies of severe sepsis. Multivariable analyses incorporated propensity scores, treatment, and significant baseline risk factors as independent variables in logistic regression models for 2 outcomes: serious adverse events that were observed during infusion and 28-day, all-cause mortality rates. Adjusted odds ratios were calculated for clinically important strata. Multiple subcategories of serious bleeding-event rates are presented.

RESULTS

Although surgical patients who were treated with drotrecogin alfa [activated] (DrotAA) experienced a greater proportion of serious bleeding events during the infusion period, most of the patients were treated without fatal consequence. A 10.7% absolute all cause mortality risk reduction (adjusted odds ratio, 0.66; 95% CI, 0.45-0.97) was observed for DrotAA-treated, high-risk (Acute Physiology and Chronic Health Evaluation II, >/= 25) surgical patients. We could not demonstrate a survival benefit in DrotAA-treated, low-risk (Acute Physiology and Chronic Health Evaluation II, <25) surgical patients. When surgical patients were stratified by number of organ dysfunctions, absolute risk reductions were observed in both categories: multiorgan (4.3%) and single (4.5%).

CONCLUSION

International Integrated Database for the Evaluation of Severe Sepsis and Drotrecogin alfa (activated) Therapy analyses affirmed the favorable benefit/risk profile of DrotAA for surgical patients. The serious adverse event rate that was experienced by surgical patients during the study drug infusion period was 7.5% in the DrotAA-treated group versus 6.3% in the placebo-treated group (odds ratio, 1.41; 95% CI, 0.89-2.25). The clinical benefit of DrotAA therapy paralleled baseline risk of death and substantiated findings from the Protein C Worldwide Evaluation in Severe Sepsis study. Future analyses are needed to evaluate the special relationships among sepsis severity, bleeding management, and the postoperative timing of DrotAA administration.

International integrated database for the evaluation of severe sepsis and drotrecogin alfa (activated) therapy: analysis of efficacy and safety data in a large surgical cohort

BACKGROUND

The International Integrated Database for the Evaluation of Severe Sepsis and Drotrecogin alfa (activated) Therapy includes an extensive cohort of surgical patients (1659/4459; 37%). This database broadens the experience reported on a comparatively small set of surgical patients from the pivotal Protein C Worldwide Evaluation in Severe Sepsis trial to examine issues of safety and efficacy in a much larger cohort.

METHODS

We conducted a retrospective analysis of prospectively defined outcomes from 5 integrated clinical studies of severe sepsis. Multivariable analyses incorporated propensity scores, treatment, and significant baseline risk factors as independent variables in logistic regression models for 2 outcomes: serious adverse events that were observed during infusion and 28-day, all-cause mortality rates. Adjusted odds ratios were calculated for clinically important strata. Multiple subcategories of serious bleeding-event rates are presented.

RESULTS

Although surgical patients who were treated with drotrecogin alfa [activated] (DrotAA) experienced a greater proportion of serious bleeding events during the infusion period, most of the patients were treated without fatal consequence. A 10.7% absolute all cause mortality risk reduction (adjusted odds ratio, 0.66; 95% CI, 0.45-0.97) was observed for DrotAA-treated, high-risk (Acute Physiology and Chronic Health Evaluation II, >or=25) surgical patients. We could not demonstrate a survival benefit in DrotAA-treated, low-risk (Acute Physiology and Chronic Health Evaluation II, <25) surgical patients. When surgical patients were stratified by number of organ dysfunctions, absolute risk reductions were observed in both categories: multiorgan (4.3%) and single (4.5%).

CONCLUSION

International Integrated Database for the Evaluation of Severe Sepsis and Drotrecogin alfa (activated) Therapy analyses affirmed the favorable benefit/risk profile of DrotAA for surgical patients. The serious adverse event rate that was experienced by surgical patients during the study drug infusion period was 7.5% in the DrotAA-treated group versus 6.3% in the placebo-treated group (odds ratio, 1.41; 95% CI, 0.89-2.25). The clinical benefit of DrotAA therapy paralleled baseline risk of death and substantiated findings from the Protein C Worldwide Evaluation in Severe Sepsis study. Future analyses are needed to evaluate the special relationships among sepsis severity, bleeding management, and the postoperative timing of DrotAA administration.

Efficacy and Safety of Drotrecogin Alfa (Activated) for the Therapy of Surgical Patients with Severe Sepsis

BACKGROUND

The efficacy of therapy with drotrecogin alfa (activated) (DrotAA) (recombinant human activated protein C) for surgical patients with severe sepsis has been questioned, and there is concern that patients who have undergone surgery recently may be at increased risk of bleeding complications from the drug. This review was performed to analyze recent data and clinical trends in the management of surgical patients with severe sepsis with respect to the efficacy and safety of therapy with DrotAA.

METHODS

Review and synthesis of the pertinent English-language literature.

RESULTS

Source control is the mainstay of therapy for surgical infections, including intraabdominal infections, whereas antibiotics, fluid resuscitation, and support of visceral organ function are necessary adjuncts. Therapy with DrotAA can be given to surgical patients, albeit with some delay (most protocols specify a 12-h wait after major surgery to mitigate the perceived increased risk of bleeding), but efficacy as well as safety have been questioned. In the pivotal PROWESS clinical trial, DrotAA therapy did not appear to be efficacious for surgical sepsis, but rigorous scrutiny of surgical indications and adequacy of source control by blinded reappraisal of the PROWESS database suggested that DrotAA therapy may be effective for surgical patients at high risk of death (Acute Physiology and Chronic Health Evaluation [APACHE] II score>or=25 points). Several comparable studies have now been aggregated in the INDEPTH database, which shows a significant reduction in mortality (OR 0.66; 95% CI 0.45-0.97) for therapy with DrotAA of surgical patients with severe sepsis and a high risk of death. The risk of bleeding is higher in surgical patients compared with DrotAA-treated non-surgical patients, but there is a substantial improvement in survival with DrotAA treatment. In contrast, surgical patients at a lower risk of death do not benefit from therapy with DrotAA but are placed at risk for bleeding.

CONCLUSION

Accumulating experience indicates that surgical patients with severe sepsis and a high risk of death (APACHE II>or=25 points) have a significantly lower mortality rate if treated with DrotAA. The increased risk of bleeding associated with therapy is acceptable given the clear improvement in survival. Surgical patients with sepsis who are at lower risk of death do not appear to benefit from therapy with DrotAA, which should be withheld in most circumstances because of the increased risk of bleeding.

Influence of orthostatic hypotension on mortality among patients discharged from an acute geriatric ward

BACKGROUND

Orthostatic hypotension (OH) is a common finding among older patients. The impact of OH on mortality is unknown.

OBJECTIVE

To study the long-term effect of OH on total and cardiovascular mortality.

PATIENTS AND METHODS

A total of 471 inpatients (227 males and 244 females), with a mean age of 81.5 years who were hospitalized in an acute geriatric ward between the years 1999 and 2000 were included in the study. Orthostatic tests were performed 3 times during the day on all patients near the time of discharge. Orthostatic hypotension was defined as a fall of at least 20 mmHg in systolic blood pressure (BP) and/or 10 mmHg in diastolic BP upon assuming an upright posture at least twice during the day. Patients were followed until August 31, 2004. Mortality data were taken from death certificates.

RESULTS

One hundred and sixty-one patients (34.2%) experienced OH at least twice. Orthostatic hypotension had no effect on all cause and cause specific mortality. Over a follow-up of 3.47+/-1.87 years 249 patients (52.8%) had died 83 of whom (33.3%) had OH. Age-adjusted mortality rates in those with and without OH were 13.4 and 15.7 per 100 person-years, respectively. Cox proportional hazards model analysis demonstrated that male gender, age, diabetes mellitus, and congestive heart failure increased and high body mass index decreased total mortality.

CONCLUSIONS

Orthostatic hypotension is relatively common in elderly patients discharged from acute geriatric wards, but has no impact on vascular and nonvascular mortality.

The Impact of Diabetes in Patients with Necrotizing Soft Tissue Infections

BACKGROUND

Given the association of diabetes with necrotizing soft tissue infections (NSTIs) and hyperglycemia with mortality in critically ill patients, this study investigates the impact of diabetes and hyperglycemia in NSTI patients.

METHODS

This is a retrospective review of NSTI patients at LBJ General Hospital between January 1995 and December 2002, assessing infectious morbidity, mortality, and length of hospital stay.

RESULTS

There was a trend towards increased infectious complications, defined as a hospital-acquired (not present within 48 h of presentation) infection at a secondary site, amongst diabetic patients (RR 2.1, 95% CI 0.7-6.8) and patients with admission hyperglycemia greater than 200 mg/dL (OR 1.9, 95% CI 0.7-5.7) but not with admission hyperglycemia greater than 120 mg/dL (OR 1.6, 95% CI 0.3-8.7). Patients with an infectious complication had a longer hospital stay (median, interquartile range [IQR]; 36, 30-44 days vs. 10, 7-20 days, p < 0.001), increased mortality (29% vs. 7%, p = 0.05), and poorer outcome defined as death, amputation, or hospital stay exceeding the 75th percentile for length of stay (79% vs. 20%, p < 0.001).

CONCLUSIONS

Diabetes mellitus and admission hyperglycemia may increase infectious complications in NSTI patients, predicting a longer and more complicated hospital course. Further study is required to define the optimal metabolic target in this patient population.

Outcome of severe acute pancreatitis

BACKGROUND

The treatment of severe acute pancreatitis has been evolving from routine operative management to nonoperative care for patients without evidence of pancreatic infection.

METHODS

Retrospective chart review of patients with severe acute pancreatitis at a single institution during a 9-year period.

RESULTS

Sixty consecutive patients had severe pancreatitis. Forty-two had pancreatic necrosis on computed axial tomography (13 infected and 29 sterile). Patients with infected necrosis and 8 with sterile necrosis had operative debridement; the remaining patients were managed without operation (n = 39). The overall mortality was 15%. Mortality was directly related to the Acute Physiology and Chronic Health Examination II and Marshall organ failure scores (P <0.001). Patients who died had a greater incidence of nosocomial infection.

CONCLUSIONS

Patients with infected pancreatic necrosis require early operative debridement, whereas those with sterile necrosis or severe pancreatitis without necrosis can usually be managed safely without surgery.