Reference: Velazquez EJ, Lee KL, Deja MA, et al. Coronary-artery bypass surgery in patients with left ventricular dysfunction. N Engl J Med. 2011;364(17):1607-1616.
Linezolid Not Superior to Glycopeptide Antibiotics in Treatment of Nosocomial Pneumonia
Clinical question: Is linezolid superior to glycopeptide antibiotics in the treatment of nosocomial pneumonia?
Background: Current ATS/IDSA guidelines suggest that linezolid might be preferred over glycopeptide antibiotics (i.e. vancomycin and teicoplanin) for methicillin-resistant Staphylococcus aureus (MRSA) pneumonia, although this recommendation is based on a retrospective subgroup analysis of one randomized trial. No systematic reviews have looked at the comparative efficacy and safety of linezolid and glycopeptide antibiotics for nosocomial pneumonia.
Study design: Meta-analysis using a highly sensitive search method.
Setting: Eight multicenter, randomized controlled trials (RCTs).
Synopsis: The study authors retrieved 762 articles with a highly sensitive search strategy, from which eight RCTs were identified that met study criteria for a total of 1,641 patients. Primary outcome of clinical success at test-of-cure was not different between the two classes of antibiotics (pooled RR 1.04, 95% CI 0.97-1.11, P=0.28). Other endpoints, including mortality and microbiologic eradication, were similar between the two groups.
Clinical success in the subgroup of patients with culture-confirmed MRSA pneumonia was not different than those without culture-proven MRSA, although the study was not powered for subgroup analysis. Risk of thrombocytopenia and renal impairment were not statistically different in the limited subgroup of trials reporting this data.
The results should not be generalized to community-acquired MRSA or MRSA pneumonia with characteristics of PVL toxin-producing strain.
Bottom line: For the treatment of nosocomial pneumonia, there was no significant difference in clinical success or mortality between linezolid and glycopeptide antibiotics.
Citation: Walkey AJ, O’Donnell MR, Weiner RS. Linezolid vs. glycopeptide antibiotics for the treatment of suspected methicillin-resistant Staphylococcus aureus nosocomial pneumonia. Chest. 2011;139: 1148-1155.
CRP and Procalcitonin Independently Differentiated Pneumonia from Asthma or COPD Exacerbation
Clinical question: Are biomarkers such as CRP or procalcitonin useful in differentiating pneumonia from asthma or COPD exacerbation in hospitalized patients?
Background: Antibiotic overuse is associated with the emergence of drug resistance. One potential strategy to decrease antibiotic overuse is biomarker-guided therapy. Several randomized controlled trials (RCT) with procalcitonin-guided therapy have resulted in reduced antibiotic use for symptoms of acute respiratory tract infections (RTI). The use of CRP as a biomarker in acute RTI is not as well-described.
Study design: Prospective, observational, diagnostic accuracy study.
Setting: Winter months, 2006 to 2008, in two hospitals in England.
Synopsis: The study examined 319 patients: 62 with pneumonia, 96 with asthma exacerbation, and 161 with COPD exacerbation. Patients with pneumonia had significantly higher procalcitonin and CRP levels than those with COPD (P<0.0001) or asthma (P<0.0001). The area under receiver operator characteristic curve for distinguishing between pneumonia (requiring antibiotics) and asthma exacerbation (not requiring antibiotics) was 0.93 (0.88-0.98) for procalcitonin and 0.96 (0.93-1.00) for CRP. A CRP value >48 mg/L had a sensitivity of 91% (95% CI 80%-97%) and specificity of 93% (95% CI 86-98).
Using this CRP threshold, antibiotic use would have been reduced by 88% in asthma exacerbation, 76% in COPD exacerbation, and 9% in pneumonia cases.
This strategy was developed in a single-center study and requires further validation in a multicenter RCT.
Bottom line: Procalcitonin and CRP were elevated in patients with pneumonia compared to patients with asthma or COPD exacerbation and might be useful in guiding antibiotic usage.
Citation: Bafadhel, M, Clark TW, Reid, C, et al. Procalcitonin and C-reactive protein in hospitalized adult patients with community-acquired pneumonia or exacerbation of asthma or COPD. Chest. 2011;139:1410-1418.