Clinical and microbiological characteristics of bloodstream infections due to AmpC ß-lactamase producing Enterobacteriaceae: an active surveillance cohort in a large centralized Canadian region.

BACKGROUND: The objective of this study was to describe the clinical and microbiological characteristics of bloodstream infections (BSIs) due to AmpC producing Enterobacteriaceae (AE) in a large centralized Canadian region over a 9-year period. METHODS: An active surveillance cohort design in Calgary, Canada. RESULTS: A cohort of 458 episodes of BSIs caused by AE was assembled for analysis. The majority of infections were of nosocomial origin with unknown sources. Enterobacter spp. was the most common species while BSIs due to Serratia spp. had a significant higher mortality when compared to other AE. Delays in empiric or definitive antibiotic therapy were not associated with a difference in outcome. However, patients that did not receive any empiric antimicrobial therapy had increased mortality (3/5; 60% vs. 57/453; 13%; p = 0.018) as did those that did not receive definitive therapy (6/17; 35% vs. 54/441; 12%; p = 0.015). CONCLUSIONS: Delays in therapy were not associated with adverse outcomes although lack of active therapy was associated with increased mortality. A strategy for BSIs due to AE where ß-lactam antibiotics (including oxyimino-cephalosporins) are used initially followed by a switch to non-ß-lactam antibiotics once susceptibility results are available is effective.

Quality improvement practices used by teaching versus non-teaching trauma centres: analysis of a multinational survey of adult trauma centres in the United States, Canada, Australia, and New Zealand.

BACKGROUND: Although studies have suggested that a relationship exists between hospital teaching status and quality improvement activities, it is unknown whether this relationship exists for trauma centres. METHODS: We surveyed 249 adult trauma centres in the United States, Canada, Australia, and New Zealand (76% response rate) regarding their quality improvement programs. Trauma centres were stratified into two groups (teaching [academic-based or -affiliated] versus non-teaching) and their quality improvement programs were compared. RESULTS: All participating trauma centres reported using a trauma registry and measuring quality of care. Teaching centres were more likely than non-teaching centres to use indicators whose content evaluated treatment (18% vs. 14%, p < 0.001) as well as the Institute of Medicine aim of timeliness of care (23% vs. 20%, p < 0.001). Non-teaching centres were more likely to use indicators whose content evaluated triage and patient flow (15% vs. 18%, p < 0.001) as well as the Institute of Medicine aim of efficiency of care (25% vs. 30%, p < 0.001). While over 80% of teaching centres used time to laparotomy, pulmonary complications, in hospital mortality, and appropriate admission physician/service as quality indicators, only two of these (in hospital mortality and appropriate admission physician/service) were used by over half of non-teaching trauma centres. The majority of centres reported using morbidity and mortality conferences (96% vs. 97%, p = 0.61) and quality of care audits (94% vs. 88%, p = 0.08) while approximately half used report cards (51% vs. 43%, p = 0.22). CONCLUSIONS: Teaching and non-teaching centres reported being engaged in quality improvement and exhibited largely similar quality improvement activities. However, differences exist in the type and frequency of quality indicators utilized among teaching versus non-teaching trauma centres.

Diagnostic accuracy of computed tomographic angiography for blunt cerebrovascular injury detection in trauma patients: a systematic review and meta-analysis.

OBJECTIVE: To compare the diagnostic accuracy of computed tomographic angiography (CTA) with digital subtraction angiography (DSA) for blunt cerebrovascular injury (BCVI) detection in trauma patients. BACKGROUND: Controversy exists as to whether the diagnostic performance of CTA compares favorably with the reference-standard, DSA. METHODS: We searched electronic databases (1950 to May 22, 2012), article bibliographies, conference proceedings (2008-2011), and clinical trial registries for studies comparing the accuracy of CTA with DSA for BCVI detection in trauma patients. Pooled estimates of sensitivity, specificity, and positive and negative likelihood ratios were calculated using bivariate random effects models. RESULTS: Eight studies that examined 5704 carotid or vertebral arteries in 1426 trauma patients met inclusion criteria. The pooled sensitivity and specificity for BCVI detection with CTA versus DSA was 66% (95% CI, 49%-79%; I = 80.4%) and 97% (95% CI, 91%-99%; I = 94.6%), respectively. Corresponding pooled positive and negative likelihood ratios were 20.0 (95% CI, 6.9-58.4; I = 87.7%) and 0.35 (95% CI, 0.22-0.56; I = 74.9%), respectively. Although pooled sensitivity varied with the number of available CT slices, the training of interpreting radiologists, and in a pattern suggestive of differences in diagnostic threshold for judging CTA positivity, it remained 80% or less among studies that used scanners with 16 or more slices per rotation and where the CTA was read by neuroradiologists. CONCLUSIONS: Existing evidence suggests that the diagnostic performance of CTA varies considerably across studies, likely due to an implicit variation in diagnostic threshold across trauma centers. Moreover, although CTA appears to lack sensitivity to adequately rule out BCVI, it may be useful to rule in BCVI among trauma patients with a high pretest probability of injury.

Attenuation of leptin action and regulation of obesity by protein tyrosine phosphatase 1B.

Common obesity is primarily characterized by resistance to the actions of the hormone leptin. Mice deficient in protein tyrosine phosphatase 1B (PTP1B) are resistant to diabetes and diet-induced obesity, prompting us to further define the relationship between PTP1B and leptin in modulating obesity. Leptin-deficient (Lep(ob/ob)) mice lacking PTP1B exhibit an attenuated weight gain, a decrease in adipose tissue, and an increase in resting metabolic rate. Furthermore, PTP1B-deficient mice show an enhanced response toward leptin-mediated weight loss and suppression of feeding. Hypothalami from these mice also display markedly increased leptin-induced Stat3 phosphorylation. Finally, substrate-trapping experiments demonstrate that leptin-activated Jak2, but not Stat3 or the leptin receptor, is a substrate of PTP1B. These results suggest that PTP1B negatively regulates leptin signaling, and provide one mechanism by which it may regulate obesity.

Clinical outcome of empiric antimicrobial therapy of bacteremia due to extended-spectrum beta-lactamase producing Escherichia coli and Klebsiella pneumoniae.

BACKGROUND: Prompt administration of adequate empiric antimicrobial therapy is a major determinant influencing the outcome of serious infections. The objective of this study was to describe empiric antimicrobial therapy employed and assess its effect on the outcome of patients bacteremic with extended-spectrum beta-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae. FINDINGS: A retrospective surveillance study of all patients with bacteremias caused by ESBL-producing E. coli and K. pneumoniae (EK-ESBL) from 2000-2007 in the Calgary Health Region was conducted. Data were available for 79 episodes of bacteremia among 76 patients. Forty-four (56%) were male, the median age was 70.0 yrs [interquartile range (IQR) 60.6-70.1 yrs], and 72 (91%) episodes were E. coli. Seventy-four episodes (94%) were treated with empiric therapy within the first 48 hours. A non-statistically significant increased mortality occurred in those treated empirically with a beta-lactam/beta-lactamase inhibitor combination (6/16; 38% vs. 10/53; 18%; p = 0.063) while empiric carbapenem therapy was associated with lower mortality (0/10 died vs. 16/53 (30%), p = 0.089). Only 42 (53%) episodes received adequate therapy within the first 48 hours. The median time to first adequate antibiotic therapy was 41.0 hours [IQR 5.8-59.5] (n = 75). The case-fatality rate was not different among those that received adequate compared to inadequate therapy by 48 hours as compared to inadequate empiric therapy (9/42; 21% vs. 7/37; 19%; p = 1.0). CONCLUSION: Inadequate empiric therapy is common among patients with EK-ESBL bacteremia in our region but was not associated with adverse mortality outcome.