Antibiotics improve survival and alter the inflammatory profile in a murine model of sepsis from Pseudomonas aeruginosa pneumonia.
ABSTRACT Differing antibiotic regimens can influence both survival and the inflammatory state in sepsis. We investigated whether the addition and/or type of antimicrobial agent could effect mortality in a murine model of Pseudomonas aeruginosa pneumonia-induced sepsis and if antibiotics altered systemic levels of cytokines. FVB/N mice were subjected to intratracheal injection of pathogenic bacteria and were given gentamicin, imipenem, or 0.9% NaCl 2 h after surgery, which continued every 12 h for a total of six doses. Survival at 7 days (n = 24 in each group) was 100% for mice given gentamicin, 88% for mice given imipenem, and 8% for sham mice treated with 0.9% NaCl (P < 0.0001). Systemic interleukin (IL) 6 levels were assayed 6 h postoperatively on all mice to see if they were predictive of outcome. Plasma IL-6 levels above 3,600 pg/mL were associated with a 100% mortality, levels under 1,200 pg/mL were associated with a 100% survival, and levels between 1,200 and 3,600 pg/mL had no utility in predicting mortality. In a separate experiment, mice were sacrificed at 3, 6, 12 or 24 h after instillation of P. aeruginosa and were assayed for levels of TNF-alpha, IL-6, IL-10, and IL-12. Significant alterations in the proinflammatory cytokines TNF-alpha and IL-6 were present at all time points except 3 h between mice treated with antibiotics and sham controls. In contrast, statistically significant differences in the anti-inflammatory cytokine IL-10 were present between the groups only at 6 h, and levels of IL-12 were similar at all time points. These results indicate that both gentamicin and imipenem increase survival at least 10-fold in a model of pneumonia-induced monomicrobial sepsis, and this is predominantly associated with a down-regulation of proinflammatory cytokines.
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ABSTRACT: Sepsis is a lethal disease caused by a systemic microbial infection that spreads via the bloodstream to overwhelm the body's defenses. Current therapeutic approaches are often suboptimal, in part, because they do not fully eliminate the pathogen, and hence the source of deadly toxins. Here we describe an extracorporeal blood cleansing device to selectively remove pathogens from contaminated blood and thereby enhance the patient's response to antibiotic therapy. Immunomagnetic microbeads were modified to create magnetic opsonins that were used to cleanse flowing human whole blood of Candida albicans fungi, a leading cause of sepsis-related deaths. The micromagnetic-microfluidic blood cleansing device generates magnetic field gradients across vertically stacked channels to enable continuous and high throughput separation of fungi from flowing whole blood. A multiplexed version of the device containing four parallel channels achieved over 80% clearance of fungi from contaminated blood at a flow rate of 20 mL/h in a single pass, a rate 1000 times faster than a previously described prototype micromagnetic-microfluidic cell separation system. These results provide the first proof-of-principle that a multiplexed micromagnetic-microfluidic separation system can be used to cleanse pathogens from flowing human blood at a rate and separation efficiency that is relevant for clinical applications.Lab on a Chip 06/2009; 9(9):1171-7. · 5.70 Impact Factor
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ABSTRACT: Pathogens that cause pneumonia may be treated in a targeted fashion by antibiotics, but if this therapy fails, then treatment involves only nonspecific supportive measures, independent of the inciting infection. The purpose of this study was to determine whether host response is similar after disparate infections with similar mortalities. Prospective, randomized controlled study. Animal laboratory in a university medical center. Pneumonia was induced in FVB/N mice by either Streptococcus pneumoniae or two different concentrations of Pseudomonas aeruginosa. Plasma and bronchoalveolar lavage fluid from septic animals was assayed by a microarray immunoassay measuring 18 inflammatory mediators at multiple time points. The host response was dependent on the causative organism as well as kinetics of mortality, but the pro-inflammatory and anti-inflammatory responses were independent of inoculum concentration or degree of bacteremia. Pneumonia caused by different concentrations of the same bacteria, Pseudomonas aeruginosa, also yielded distinct inflammatory responses; however, inflammatory mediator expression did not directly track the severity of infection. For all infections, the host response was compartmentalized, with markedly different concentrations of inflammatory mediators in the systemic circulation and the lungs. Hierarchical clustering analysis resulted in the identification of five distinct clusters of the host response to bacterial infection. Principal components analysis correlated pulmonary macrophage inflammatory peptide-2 and interleukin-10 with progression of infection, whereas elevated plasma tumor necrosis factor sr2 and macrophage chemotactic peptide-1 were indicative of fulminant disease with >90% mortality within 48 hrs. Septic mice have distinct local and systemic responses to Streptococcus pneumoniae and Pseudomonas aeruginosa pneumonia. Targeting specific host inflammatory responses induced by distinct bacterial infections could represent a potential therapeutic approach in the treatment of sepsis.Critical care medicine 09/2009; 38(1):223-41. · 6.37 Impact Factor
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ABSTRACT: To determine the relationship between sublingual and intestinal mucosal microcirculatory perfusion. Observational, experimental study. University-affiliated large animal laboratory. Ten fasted, anesthetized, mechanically ventilated, male pigs randomized to a sham group (n = 3) or to a hyperdynamic septic shock group (n = 7) in which cholangitis was induced by direct infusion of Escherichia coli into the common bile duct. This model was developed because it is not accompanied by changes in intra-abdominal pressure. The sublingual and intestinal microcirculations were simultaneously assessed at 4-hr intervals for up to 12 hrs with a modified orthogonal polarization spectral device and functional microvessel density and erythrocyte velocity were measured quantitatively. In sham animals, both regions maintained a stable functional microvessel density and erythrocyte velocity throughout the study period. In contrast, in septic animals, already after 4 hrs of sepsis, functional microvessel density was markedly decreased (>50%) in the sublingual and gut regions; mean erythrocyte velocity decreased dramatically and similarly in both regions, from 1022 +/- 80 to 265 +/- 43 mum/sec in the sublingual region and from 1068 +/- 45 to 243 +/- 115 mum/sec in the gut (p < 0.001, at T12). There was a significant correlation between the sublingual and gut microcirculations in septic animals (r = 0.92, p < 0.0001). The severity and the time course of microcirculatory changes were similar in the sublingual and in the gut region in this clinically relevant model of severe sepsis. These findings support the sublingual region as an appropriate region to monitor the microcirculation in sepsis.Critical care medicine 09/2009; 37(11):2875-81. · 6.37 Impact Factor