The surgical Infection Society Revised Guidelines on the management of intra-abdominal infection

BACKGROUND: Previous evidence-based guidelines on the management of intra-abdominal infection (IAI) were published by the Surgical Infection Society (SIS) in 1992, 2002, and 2010. At the time the most recent guideline was released, the plan was to update the guideline every five years to ensure the timeliness and appropriateness of the recommendations. METHODS: Based on the previous guidelines, the task force outlined a number of topics related to the treatment of patients with IAI and then developed key questions on these various topics. All questions were approached using general and specific literature searches, focusing on articles and other information published since 2008. These publications and additional materials published before 2008 were reviewed by the task force as a whole or by individual subgroups as to relevance to individual questions. Recommendations were developed by a process of iterative consensus, with all task force members voting to accept or reject each recommendation. Grading was based on the GRADE (Grades of Recommendation Assessment, Development, and Evaluation) system; the quality of the evidence was graded as high, moderate, or weak, and the strength of the recommendation was graded as strong or weak. Review of the document was performed by members of the SIS who were not on the task force. After responses were made to all critiques, the document was approved as an official guideline of the SIS by the Executive Council. RESULTS: This guideline summarizes the current recommendations developed by the task force on the treatment of patients who have IAI. Evidence-based recommendations have been made regarding risk assessment in individual patients; source control; the timing, selection, and duration of antimicrobial therapy; and suggested approaches to patients who fail initial therapy. Additional recommendations related to the treatment of pediatric patients with IAI have been included. SUMMARY: The current recommendations of the SIS regarding the treatment of patients with IAI are provided in this guideline.(AU)

Thrombospondin-1 triggers macrophage IL-10 production and promotes resolution of experimental lung injury.

Mononuclear phagocyte recognition of apoptotic cells triggering suppressive cytokine signaling is a key event in inflammation resolution from injury. Mice deficient in thrombospondin (TSP)-1 (thbs1⁻/⁻), an extracellular matrix glycoprotein that bridges cell-cell interactions, are prone to lipopolysaccharide-induced lung injury and show defective macrophage interleukin (IL)-10 production during the resolution phase of inflammation. Reconstitution of IL-10 rescues thbs1⁻/⁻ mice from persistent neutrophilic lung inflammation and injury and thbs1⁻/⁻ alveolar macrophages show defective IL-10 production following intratracheal instillation of apoptotic neutrophils despite intact efferocytosis. Following co-culture with apoptotic neutrophils, thbs1⁻/⁻ macrophages show a selective defect in IL-10 production, whereas prostaglandin E2 and transforming growth factor beta 1 responses remain intact. Full macrophage IL-10 responses require the engagement of TSP-1 structural repeat 2 domain and the macrophage scavenger receptor CD36 LIMP-II Emp sequence homology (CLESH) domain in vitro. Although TSP-1 is not essential for macrophage engulfment of apoptotic neutrophils in vivo, TSP-1 aids in the curtailment of inflammatory responses during the resolution phase of injury in the lungs by providing a means by which apoptotic cells are recognized and trigger optimal IL-10 production by macrophages.

Red cell microparticle enumeration: validation of a flow cytometric approach.

BACKGROUND AND OBJECTIVES: There is growing interest in the clinical application of red blood cell (RBC) microparticle (MP) enumeration as they have been postulated to be effectors of coagulation and inflammation following transfusion and in sickle cell disease. No uniform approach in MP enumeration exists and a key limitation is the lack of an internal validation process. We present and validate a flow cytometric approach where an internal standard is utilized. MATERIALS AND METHODS: Glycophorin A(+) Annexin V(+) events were enumerated using MPs isolated from RBC units or plasma samples obtained from volunteers. A mixture of absolute counting (7·6 µm) and calibration beads (0·5, 0·9 and 3 µm) at a fixed ratio was added to each sample. RESULTS: RBC MPs were initially selected based upon a fluorescence threshold, and the 0·5- and 0·9-µm beads defined the upper and lower light scatter distribution of MPs. The ratio of 7·6:3-µm bead events was used as an internal standard to validate the precision of MP enumeration across samples (coefficient of variation = 2·5-7·2%) and remained constant in both platelet-rich plasma (PRP) and platelet-free plasma (PFP). RBC MP counts increased in both PRP and PFP obtained from whole blood stimulated with ionophore and increasing calcium concentrations, with PRP showing higher MP counts than PFP at every concentration studied. CONCLUSION: This method is a useful strategy to detect RBC MP counts across bio-samples provided that the flow cytometer can reliably discriminate the size of the calibration beads.

Epithelial cyclooxygenase-2 expression: a model for pathogenesis of colon cancer.

BACKGROUND: Recent studies indicate a close relationship between cyclooxygense-2 (COX-2) expression and the pathogenesis of colorectal cancer, yet little information exists regarding the stimuli and pathways involved in COX-2 expression by the colonic epithelium. We studied the induction of COX-2 in response to such environmental stress as hyperosmolarity and lipopolysaccharide (LPS) in a human colon cell line. We further investigated the transduction cascades mediating COX-2 expression, focusing upon the mitogen-activated protein kinase pathways p38 and extracellular signal-regulated kinase (ERK). MATERIALS AND METHODS: Human colon cancer cells (Caco-2) were stimulated with increasing concentrations of sodium chloride (NaCl) or LPS. Total protein was extracted at different time points and subjected to Western blot analysis with antibodies to human COX-2, COX-1, or phospho-specific antibodies to ERK and p38. RESULTS: LPS failed to induce COX-2 or COX-1 expression. Hyperosmolarity induced COX-2 expression by 2 h, with peak levels occurring at 6-8 h. NaCl at 40 and 100 mM induced a 2-fold and more than 50-fold increase in COX-2 expression, respectively; COX-1 expression was not affected. Hyperosmolarity induced both p38 and ERK activation within 30 min; however, only p38 inhibition attenuated osmotic-induced COX-2 expression; inhibition of ERK activation had no effect. CONCLUSIONS: Increase in osmolarity activates p38 and induces COX-2 expression in the colonic epithelium. The lack of response to LPS is teleologically expected of the colonic epithelium that is in constant contact with the fecal bacteria. This model also predicts that an increase in luminal osmolarity in the colon may induce COX-2 and thereby promote a neoplastic phenotype.

Adherence regulates macrophage signal transduction and primes tumor necrosis factor production.

While monocyte/macrophage (Mphi) adherence to a matrix is necessary for differentiation and prolonged survival, the effect of adherence on the signaling mechanisms responsible for Mphi activation is unknown. Lipopolysaccharide (LPS) activates Mphi by signaling through members of the mitogen activated protein kinase (MAPK) family thereby inducing transcription of proinflammatory cytokines, such as TNF-alpha. Since adherence has been shown to affect different activities of various myeloid phagocytes, we investigated whether adherence affects intracellular signaling and modulates activation of the Mphi proinflammatory phenotype. We assessed the effect of adherence on activation of rabbit alveolar Mphi by measuring LPS-induced TNF-alpha mRNA and TNF-alpha secreted product in adherent versus nonadherent cells, in vitro. The effect of adherence on LPS-induced activation of MAPK was assessed by western analysis using a dual phosphospecific antibody against p38MAPK, p42,44ERK, and p54SAPK. LPS is known to induce activation of NF-kappaB and AP-1. Modulation of these two transcription factors by LPS under adherent versus nonadherent conditions was evaluated by gel-shift analyses. The results were that adherent cells treated with LPS, 10 ng/mL or 1 microg/ml, elicited a 26- and 132-fold increase, respectively, in TNF-alpha production. Nonadherent cells did not elicit significant TNF-alpha in response to LPS. Adherence alone induced significant ERK and AP-1 activation, but did not stimulate a significant TNF-alpha response and no further activation of ERK and AP-1 was observed with LPS stimulation. Adherence alone did not activate p38MAPK or NF-kappaB, but primed Mphi for an augmented response to LPS in activation of p38, NF-kappaB and in production of TNF-alpha. We conclude that adherence primes Mphi for activation and regulates MAPK signal transduction pathways.

Hypertonic saline solution induces prostacyclin production by increasing cyclooxygenase-2 expression.

BACKGROUND: Previously, we demonstrated that hypertonic saline solution (HTS) and endotoxin (lipopolysaccharide [LPS]) induce prostacyclin (PGI(2)) production in human endothelial cells. Here, we hypothesized that HTS and LPS may induce PGI(2) production by increasing cyclooxygenase (COX) expression. We further examined the activation of p38 and extracellular signal-regulated kinases (ERK) and questioned whether these transduction cascades might mediate COX expression. METHODS: Human umbilical vein endothelial cells were stimulated with varying concentrations of NaCl or LPS. RESULTS: HTS and LPS induced prompt activation of both p38 and ERKs that peaked at 30 minutes. HTS and LPS also induced a dose-related increase in COX-2 with maximal expression within 4 to 6 hours; there was no change in COX-1. This correlated with an increase in supernatant PGI(2) levels, which became statistically significant for NaCl of more than 40 mmol/L and for all LPS doses. The inhibition of p38 with SB202190 abrogated the osmotic and LPS-induced COX-2 expression and PGI(2) production. Inhibition of ERK activation had no effect on COX-2 expression. CONCLUSIONS: Hyperosmolarity and LPS induce, in chronologic order, p38 and ERK activation, COX-2 expression, and PGI(2) production. Because COX is the rate-limiting enzyme in prostaglandin synthesis, it is likely that the increase in PGI(2) production is due to, at least in part, the increased COX-2 expression. The data also suggest that p38 mitogen-activated protein kinase is involved in the signaling cascade for COX-2 expression.

Interactions of calcium/calmodulin-dependent protein kinases (CaMK) and extracellular-regulated kinase (ERK) in monocyte adherence and TNFalpha production.

The circulating monocyte possesses a markedly different functional phenotype relative to the macrophage (Mphi). The adhesive interactions encountered by the monocyte, en route to the inflammatory focus, generate signals that culminate in the expression of a pro-inflammatory Mphi phenotype, marked by enhanced cytokine production. Previously, we demonstrated that calcium and calmodulin are essential for maximal Mphi activation and, in particular, TNFalpha production. These effects are likely to be mediated through signal transduction kinases that require the calcium/calmodulin complex. Here, we investigated the effect of adherence on calcium/calmodulin-dependent protein kinase (CaMK) II and IV activation of the extracellular-signal regulated kinase (ERK) 1/2 cascade and on lipopolysaccharide (LPS)-induced TNFalpha production by human monocytes. Adherence activated ERK 1/2 and led to an 8-fold potentiation in LPS-induced TNFalpha production over similarly stimulated non-adherent cells. Inhibition of CaMK II prior to adherence prevented ERK 1/2 activation and attenuated by up to 40%, the TNFalpha response to subsequent LPS stimulation. CaMK II inhibition after adherence, however, failed to modify cytokine release. Inhibition of CaMK IV, both after adherence and in non-adherent monocytes, significantly inhibited LPS-induced ERK 1/2 activation and abrogated TNFalpha production by up to 75%. These data suggest that the function of CaMK II in TNFalpha production by adherent monocytes occurs during adhesion, is mediated in part by activation of ERK 1/2, and appears to "prime" the monocyte for enhanced cytokine production. CaMK IV, through activation of ERK 1/2, appears to have a direct role in the LPS signal transduction for TNFalpha production.

Priming interleukin 8 production: role of platelet-activating factor and p38.

HYPOTHESIS: Platelet-activating factor (PAF) activates p38, an important intracellular signal transduction kinase, and primes human mononuclear cells for the production of interleukin 8 (IL-8), a potent chemoattractant and activator of neutrophils. METHODS: Human mononuclear cells were isolated from healthy adults by Ficoll-paque density-gradient centrifugation. Interleukin-8 in the supernatant was measured by enzyme-linked immunosorbent assay. Dual phospho-specific p38 antibody was used to detect activated p38 by Western blotting. RESULTS: Lipopolysaccharide (LPS) and PAF activated p38. There was a shorter latency to peak p38 activation with PAF vs LPS stimulation, 5 vs 30 minutes. Platelet-activating factor-induced p38 activation was calcium dependent because it was inhibited by ethyleneglycoltetracetic acid. Lipopolysaccharide, 0.01 to 1.00 ng/mL, induced significant IL-8 production. Although PAF did not induce significant IL-8 production, it potentiated LPS-induced IL-8 production. Production of IL-8, in response to LPS alone or in combination with PAF, was inhibited by SB202190, a specific p38 inhibitor. CONCLUSIONS: Although LPS and PAF activated p38, only LPS induced IL-8 production; PAF acted as a priming agent. It seems that p38 activation is necessary but not sufficient for IL-8 production by human mononuclear cells. Identifying and evaluating the activation state of inflammatory signal transduction pathways might lead to methods for controlling and preventing neutrophil-induced tissue injury without interfering with the normal host immune response.

Prognostic factors in patients with inferior vena cava injuries.

Inferior vena cava (IVC) injuries are potentially devastating insults that continue to be associated with high mortality despite advances in prehospital and in-hospital critical care. Between 1987 and 1996, 37 patients (32 males and 5 females; average age, 30 years) were identified from the trauma registry as having sustained IVC trauma. Overall mortality was 51 per cent (n = 19), with 13 intraoperative deaths and five patients dying within the first 48 hours. Blunt IVC injuries (n = 8) had a higher associated mortality than penetrating wounds (63% versus 48%). Of the 29 patients with penetrating IVC trauma, the wounding agent influenced mortality (shotgun-100% versus gunshot-43% versus stab-0%). Anatomical location of injury was also predictive of death [suprahepatic (n = 3)-100% versus retrohepatic (n = 9)-78% versus suprarenal (n = 6)-33% versus juxtarenal (n = 2)-50% versus infrarenal (n = 15)-33%]. A direct relationship existed between outcome and the number of associated injuries: nonsurvivors averaged four and survivors averaged three. Eighty per cent of patients sustaining four or more associated injuries died, by contrast to a 33 per cent mortality in those suffering less than four injuries. Physiological factors were also predictive of outcome. Patients in shock (systolic blood pressure < 80) on arrival had a higher mortality than those who were hemodynamically stable (76% versus 30%). Preoperative lactate levels were of prognostic value for death (> or = 4.0-59% versus < 4.0-0%), as was base deficit (< 4-22%, > or = 4, and < 10-36%, > or = 10-73%). Interestingly, neither time from injury to hospital arrival (47.4 minutes versus 33.0 minutes) nor time in the emergency department before surgery (45.6 minutes versus 42.6 minutes) differed between survivors and fatalities. Mortality remained high in the 34 patients who had operative control of their IVC injuries [lateral repair (n = 27)-44% versus ligation (n = 6)-66% versus Gortex graft (n = 1)-0%]. As wounding agent, anatomical location, associated injuries, and physiological status seem to most directly impact mortality, future efforts must focus both on establishing prevention programs directed at reducing the incidence of this injury, as well as on advancing the management of those who do survive to hospitalization, if we are to improve on the outcome of these devastating injuries.