Faculty Bibliography

Abstract This study investigates the potential clinical utility in the emergency department (ED) of an index of brain electrical activity to identify intracranial hematomas. The relationship between this index and depth, size, and type of hematoma was explored. Ten minutes of brain electrical activity was recorded from a limited montage in 38 adult patients with traumatic hematomas (CT scan positive) and 38 mild head injured controls (CT scan negative) in the ED. The volume of blood and distance from recording electrodes were measured by blinded independent experts. Brain electrical activity data were submitted to a classification algorithm independently developed traumatic brain injury (TBI) index to identify the probability of a CT+traumatic event. There was no significant relationship between the TBI-Index and type of hematoma, or distance of the bleed from recording sites. A significant correlation was found between TBI-Index and blood volume. The sensitivity to hematomas was 100%, positive predictive value was 74.5%, and positive likelihood ratio was 2.92. The TBI-Index, derived from brain electrical activity, demonstrates high accuracy for identification of traumatic hematomas. Further, this was not influenced by distance of the bleed from the recording electrodes, blood volume, or type of hematoma. Distance and volume limitations noted with other methods, (such as that based on near-infrared spectroscopy) were not found, thus suggesting the TBI-Index to be a potentially important adjunct to acute assessment of head injury. Because of the life-threatening risk of undetected hematomas (false negatives), specificity was permitted to be lower, 66%, in exchange for extremely high sensitivity.

BACKGROUND:Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of skin infections. Recent case series describe severe community-acquired pneumonia (CAP) caused by MRSA, but the prevalence and risk factors are unknown. METHODS:We prospectively enrolled adults hospitalized with CAP from 12 university-affiliated emergency departments during the winter-spring of 2006 and 2007. Clinical information and culture results were collected, and factors associated with MRSA were assessed. RESULTS:Of 627 patients, 595 (95%) had respiratory (50%) and/or blood cultures (92%) performed. A pathogen was identified in 102 (17%); MRSA was identified in 14 (2.4%; range by site, 0%-5%) patients and in 5% of patients admitted to the intensive care unit. Two (14%) MRSA pneumonia patients died. All 9 MRSA isolates tested were pulsed-field type USA300. Features significantly associated with isolation of MRSA (as compared with any other or no pathogen) included patient history of MRSA; nursing home admission in the previous year; close contact in the previous month with someone with a skin infection; multiple infiltrates or cavities on chest radiograph; and comatose state, intubation, receipt of pressors, or death in the emergency department. CONCLUSIONS:Methicillin-resistant Staphylococcus aureus remains an uncommon cause of CAP. Detection of MRSA was associated with more severe clinical presentation.

BACKGROUND:In the past decade, new methicillin-resistant Staphylococcus aureus (MRSA) strains have emerged as a predominant cause of community-associated skin and soft-tissue infections (SSTIs). Little information exists regarding trends in MRSA prevalence and molecular characteristics or regarding antimicrobial susceptibility profiles of S. aureus isolates. METHODS:We enrolled adults with acute, purulent SSTIs presenting to a US network of 12 emergency departments during August 2008. Cultures and clinical information were collected. S. aureus isolates were characterized by antimicrobial susceptibility testing, pulsed-field gel electrophoresis, and toxin genes detection. The prevalence of S. aureus and MRSA and isolate genetic characteristics and susceptibilities were compared with those from a similar study conducted in August 2004. RESULTS:The prevalence of MRSA was 59% among all SSTIs during both study periods; however, the prevalence by site varied less in 2008 (38%-84%), compared with 2004 (15%-74%). Pulsed-field type USA300 continued to account for almost all MRSA isolates (98%). Susceptibility to trimethoprim-sulfamethoxazole, clindamycin, and tetracycline among MRSA isolates remained greater than 90% in 2008. A higher proportion of MRSA infections were treated with an agent to which the infecting isolate was susceptible in vitro in 2008 (97%), compared with 2004 (57%). CONCLUSIONS:Similar to 2004, MRSA remained the most common identifiable cause of purulent SSTIs among patients presenting to a network of US emergency departments in 2008. The infecting MRSA isolates continued to be predominantly pulsed-field type USA300 and susceptible to recommended non-β-lactam oral agents. Clinician prescribing practices have shifted from MRSA-inactive to MRSA-active empirical antimicrobial regimens.