Lipid peroxidation in Gram-negative bacteremia modulates the risk for septic shock and infections by resistant Klebsiella pneumoniae.

Controversies in outcomes with the parenteral administration of antioxidants as adjuvant therapies led to the measurement of malondialdehyde (MDA), a product of lipid peroxidation, in serum collected from 120 patients with primary Gram-negative bacteremia during the first 24 h from sepsis onset. MDA was measured by the thiobarbiturate assay, followed by high-performance liquid chromatography (HPLC) analysis. After receiver operator characteristic (ROC) curve analysis, patients were divided into those with high levels of MDA and low levels of MDA. The primary endpoint was the association of the level of MDA with septic shock. The level of MDA as an index of neutrophil function and associations with outcome and with infections by carbapenem-resistant Klebsiella pneumoniae were the secondary endpoints. In total, 63 patients had high and 57 had low MDA levels; 27% and 49.1%, respectively, had septic shock (p = 0.015). The rate of the concentration of MDA to the total neutrophil count was used as an expression of neutrophil function; this was lower among patients with septic shock. The odds ratio (OR) for death among patients without septic shock and low level of MDA was 4.00; this was 0.48 for patients with septic shock (p = 0.020 between the two ORs). The OR for resistance to carbapenems among patients with bacteremia by K. pneumoniae and low level of MDA was 7.50 (p = 0.011 compared to patients with bacteremia by other pathogens). Low level of circulating MDA is associated with susceptibility to septic shock and infections by carbapenem-resistant K. pneumoniae.

Community acquired methicillin resistant Staphylococcus aureus pneumonia: an update for the emergency and intensive care physician.

Pneumonia caused by community-acquired (CA) methicillin-resistant Staphylococcus aureus (MRSA) among individuals without healthcare-associated (HA) risk factors was first recognized a decade ago. CA-MRSA has now been established as a pathogen responsible for rapidly progressive, frequently fatal disease manifesting as necrotizing pneumonia, severe sepsis and necrotizing fasciitis. The frequency of occurrence, risk factors, and optimal treatment of CA-MRSA pneumonia remain unclear and vary significantly across countries. CA-MRSA is resistant to ß-lactam antimicrobials due to the acquisition of novel methicillin resistance genetic cassettes. Additionally many CA-MRSA strains produce Panton-Valentine leukocidin (PVL), due to which they probably exceed the virulence of hospital-acquired MRSA isolates (HA-MRSA). CA-MRSA pneumonia requires early suspicion -especially in young otherwise healthy individuals with rapidly evolving clinical picture presenting with cavitary consolidation, bilateral infiltrates, pleural effusion and hemoptysis. Prompt hospitalization and aggressive treatment with intravenous antibiotics is warranted to improve outcomes. Therapeutic approach for severe CA-MRSA infections and particularly pneumonia is generally the same as that for invasive HA-MRSA infections. New anti-MRSA agents and possible combinations are of great importance to be evaluated in the future.