Is the gram stain useful in the microbiologic diagnosis of VAP? A meta-analysis

In a meta-analysis examining respiratory specimen Gram stain for diagnosis of ventilator-associated pneumonia, absence of bacteria on Gram stain had a high negative predictive value, but a positive Gram stain correlated poorly with organisms recovered in culture. Rapid and accurate diagnosis of ventilator-associated pneumonia (VAP) is a major challenge and no generally accepted gold standard exists for VAP diagnosis. We conducted a meta-analysis to examine the role of respiratory specimen Gram stain to diagnose VAP, and the correlation with final culture results. In 21 studies, pooled sensitivity of Gram stain for VAP was 0.79 (95% confidence interval [CI], .77-0.81; P < .0001) and specificity was 0.75 (95% CI, .73-.78; P < .0001). Negative predictive value of Gram stain for a VAP prevalence of 20%-30% was 91%, suggesting that VAP is unlikely with a negative Gram stain but the positive predictive value of Gram stain was only 40%. Pooled kappa was 0.42 for gram-positive organisms and 0.34 for gram-negative organisms, suggesting fair concordance between organisms on Gram stain and recovery by culture. Therefore, a positive Gram stain should not be used to narrow anti-infective therapy until culture results become available.     

From Ulcer to Infection: An Update on Clinical Practice and Adjunctive Treatments of Diabetic Foot Ulcers

Foot ulcers are a common complication of diabetes. A fifth of all individuals with diabetes develop a diabetic foot infection and are hospitalized at least once in their lifetime. Standard of care for treatment of diabetic foot ulcers and subsequent infection involves a multimodal, interdisciplinary team approach that includes wound care, systemic antimicrobials, and surgery. However, with the relatively poor outcome for chronic, longstanding ulcers and severe infections, recent research has focused on adjunctive therapies to promote wound healing and repair. This review summarizes the underlying pathology and classification of diabetic ulcers and focuses on recent advances that have important implications for the use of adjunctive therapy for diabetic foot infections.     

Supplemental perioperative oxygen for reducing surgical site infection: a meta-analysis

Objective  To assess the efficacy of supplemental perioperative oxygenation for prevention of surgical site infection (SSI).
Data sources  Computerized PUBMED and MEDLINE search supplemented by manual searches for relevant articles.
Study selection  Randomized, controlled trials evaluating efficacy of supplemental perioperative oxygenation versus standard care for prevention of SSI in patients' undergoing colorectal surgery.
Data synthesis  Data on incidence of SSI were abstracted as dichotomous variables. Pooled estimates of the relative risk (RR) and 95% confidence interval (CI) were obtained using the DerSimonian and Laird random effects model and the Mantel-Haenzel fixed effects model. Heterogeneity was assessed using the Cochran Q statistic and I².
Results  Four randomized controlled trials met the inclusion criteria. Supplemental perioperative oxygenation resulted in a reduced incidence of SSI [RR 0.70 (95% CI 0.52–0.94), P  = 0.01], using a fixed effects model. Using the more conservative random effects model, the point estimate was similar [RR 0.74 (95% CI 0.39–1.43), P  = 0.37], but the results failed to achieve statistical significance. The I² test showed moderate heterogeneity.
Conclusions  Our analysis showed that supplemental perioperative oxygenation is beneficial in preventing SSI in patients undergoing colorectal surgery. Because of heterogeneity in study design and patient population, additional randomized trials are needed to determine whether this confers benefit in all patient populations undergoing other types of surgery. Supplemental perioperative oxygenation is a low-cost intervention that we recommend be implemented in patients undergoing colorectal surgery pending the results of further studies. Further research is needed to determine whether or not supplemental hyperoxia may cause unanticipated adverse effects.