Andrew M. Morris

Does This Adult Patient With Suspected Bacteremia Require Blood Cultures

CONTEXT Clinicians order blood cultures liberally among patients in whom bacteremia is suspected, though a small proportion of blood cultures yield true-positive results. Ordering blood cultures inappropriately may be both wasteful and harmful. OBJECTIVE To review the accuracy of easily obtained clinical and laboratory findings to inform the decision to obtain blood cultures in suspected bacteremia. DATA SOURCES AND STUDY SELECTION A MEDLINE and EMBASE search (inception to April 2012) yielded 35 studies that met inclusion criteria for evaluating the accuracy of clinical variables for bacteremia in adult immunocompetent patients, representing 4566 bacteremia and 25,946 negative blood culture episodes. DATA EXTRACTION Data were extracted to determine the prevalence and likelihood ratios (LRs) of findings for bacteremia. DATA SYNTHESIS The pretest probability of bacteremia varies depending on the clinical context, from low (eg, cellulitis: 2%) to high (eg, septic shock: 69%). Elevated temperatures alone do not accurately predict bacteremia (for ≥38°C [>100.3°F], LR, 1.9 [95% CI, 1.4-2.4]; for ≥38.5°C [>101.2°F], LR, 1.4 [95% CI, 1.1-2.0]), nor does isolated leukocytosis (LR, <1.7). The severity of chills graded on an ordinal scale (shaking chills, LR, 4.7; 95% CI, 3.0-7.2) may be more useful. Both the systemic inflammatory response syndrome (SIRS) and a multivariable decision rule with major and minor criteria are sensitive (but not specific) predictors of bacteremia (SIRS, negative LR, 0.09 [95% CI, 0.03-0.26]; decision rule, negative LR, 0.08 [95% CI, 0.04-0.17]). CONCLUSIONS Blood cultures should not be ordered for adult patients with isolated fever or leukocytosis without considering the pretest probability. SIRS and the decision rule may be helpful in identifying patients who do not need blood cultures. These conclusions do not apply to immunocompromised patients or when endocarditis is suspected.

Impact of Infectious Disease Consultation on Quality of Care, Mortality, and Length of Stay in Staphylococcus aureus Bacteremia: Results From a Large Multicenter Cohort Study

BACKGROUND We assessed the impact of infectious disease (ID) consultation on management and outcome in patients with Staphylococcus aureus bacteremia (SAB). METHODS A retrospective cohort study examined consecutive SAB patients from 6 academic and community hospitals between 2007 and 2010. Quality measures of management including echocardiography, repeat blood culture, removal of infectious foci, and antibiotic therapy were compared between ID consultation (IDC) and no ID consultation (NIDC) groups. A competing risk model with propensity score adjustment was used to compare in-hospital mortality and time to discharge. RESULTS Of 847 SAB patients, 506 (60%) patients received an ID consultation and 341 (40%) patients did not. Echocardiography was done for 371 (73%) IDC and 191 (56%) NIDC patients (P < .0001) in hospital. Blood cultures were repeated within 2-4 days of bacteremia in 207 (41%) IDC and 107 (31%) NIDC patients (P = .0058). The infectious foci removal rate was not statistically different between the 2 groups. For empiric therapy, 474 (94%) IDC and 297 (87%) NIDC patients received appropriate antibiotics (P = .0013). For patients who finished the planned course of antibiotics, 285 of 422 (68%) IDC and 141 of 262 (54%) NIDC patients received the appropriate duration of antibiotic therapy (P = .0004). In hospital, 204 (24%) patients died: 104 of 506 (21%) IDC and 100 of 341 (29%) NIDC patients. Matched by propensity score, ID consultation had a subdistribution hazard ratio of 0.72 (95% confidence interval [CI], .52-.99; P = .0451) for in-hospital mortality and 1.28 (95% CI, 1.06-1.56; P = .0109) for being discharged alive. CONCLUSIONS ID consultation is associated with better adherence to quality measures, reduced in-hospital mortality, and earlier discharge in patients with SAB.

Annualized incidence and spectrum of illness from an outbreak investigation of Bell's palsy.

Background: There are limited clinical and epidemiological data on patients diagnosed with Bell’s palsy. While investigating an apparent clustering of Bell’s palsy, we sought to characterize the spectrum of illness in patients with this diagnosis. Methods: A telephone survey of persons with idiopathic facial (Bell’s) palsy in the Greater Toronto Area (GTA, population = 4.99 million) and Nova Scotia (population = 0.93 million) from August 1 to November 15, 1997 collected information on subject demographics, neurological symptoms, constitutional symptoms, medical investigation and management. Information regarding potential risks for exposure to infectious agents, past medical history, and family history of Bell’s palsy was also collected. Subjects with other secondary causes of facial palsy were excluded. Results: In the GTA and Nova Scotia, 222 and 36 patients were diagnosed with idiopathic facial (Bell’s) palsy, respectively. The crude annualized incidence of Bell’s palsy was 15.2 and 13.1 per 100,000 population in the GTA and Nova Scotia, respectively. There was no temporal or geographical clustering, and symptomatology did not differ significantly between the two samples. The mean age was 45 years, with 55% of subjects being female. The most common symptoms accompanying Bell’s palsy were increased tearing (63%), pain in or around the ear (63%), and taste abnormalities (52%). A significant number of patients reported neurological symptoms not attributable to the facial nerve. Conclusion: No clustering of cases of Bell’s palsy was observed to support an infectious etiology for the condition. Misdiagnosis of the etiology of facial weakness is common. Patients diagnosed with Bell’s palsy have a variety of neurological symptoms, many of which cannot be attributed to a facial nerve disorder.

NOSOCOMIAL BACTERIAL MENINGITIS, INCLUDING CENTRAL NERVOUS SYSTEM SHUNT INFECTIONS

Nosocomial bacterial meningitis and CSF shunt infections result in considerable morbidity and mortality, necessitating an organized and thoughtful approach to prevention, diagnosis, and management. Prophylactic antibiotics appear to reduce the rate of postcraniotomy meningitis often caused by S. aureus. On the other hand, prophylactic antibiotics do not appear to reduce the risk of developing a CSF shunt infection. CSF shunt infections usually require shunt removal and antimicrobial chemotherapy to effect a successful outcome.

The superbugs: evolution, dissemination and fitness

Since the introduction of antibiotics, bacteria have not only evolved elegant resistance mechanisms to thwart their effect, but have also evolved ways in which to disseminate themselves or their resistance genes to other susceptible bacteria. During the past few years, research has revealed not only how such resistance mechanisms have been able to evolve and to rapidly disseminate, but also how bacteria have, in some cases, been able to adapt to this new burden of resistance with little or no cost to their fitness. Such adaptations make the control of these superbugs all the more difficult.

An antimicrobial stewardship program improves antimicrobial treatment by culture site and the quality of antimicrobial prescribing in critically ill patients

IntroductionIncreasing antimicrobial costs, reduced development of novel antimicrobials, and growing antimicrobial resistance necessitate judicious use of available agents. Antimicrobial stewardship programs (ASPs) may improve antimicrobial use in intensive care units (ICUs). Our objective was to determine whether the introduction of an ASP in an ICU altered the decision to treat cultures from sterile sites compared with nonsterile sites (which may represent colonization or contamination). We also sought to determine whether ASP education improved documentation of antimicrobial use, including an explicit statement of antimicrobial regimen, indication, duration, and de-escalation.MethodsWe retrospectively analyzed consecutive patients with positive bacterial cultures admitted to a 16-bed medical-surgical ICU over 2-month periods before and after ASP introduction (April through May 2008 and 2009, respectively). We evaluated the antimicrobial treatment of positive sterile- versus nonsterile-site cultures, specified a priori. We reviewed patient charts for clinician documentation of three specific details regarding antimicrobials: an explicit statement of antimicrobial regimen/indication, duration, and de-escalation. We also analyzed cost and defined daily doses (DDDs) (a World Health Organization (WHO) standardized metric of use) before and after ASP.ResultsPatient demographic data between the pre-ASP (n = 139) and post-ASP (n = 130) periods were similar. No difference was found in the percentage of positive cultures from sterile sites between the pre-ASP period and post-ASP period (44.9% versus 40.2%; P = 0.401). A significant increase was noted in the treatment of sterile-site cultures after ASP (64% versus 83%; P = 0.01) and a reduction in the treatment of nonsterile-site cultures (71% versus 46%; P = 0.0002). These differences were statistically significant when treatment decisions were analyzed both at an individual patient level and at an individual culture level. Increased explicit antimicrobial regimen documentation was observed after ASP (26% versus 71%; P < 0.0001). Also observed were increases in formally documented stop dates (53% versus 71%; P < 0.0001), regimen de-escalation (15% versus 23%; P = 0.026), and an overall reduction in cost and mean DDDs after ASP implementation.ConclusionsIntroduction of an ASP in the ICU was associated with improved microbiologically targeted therapy based on sterile or nonsterile cultures and improved documentation of antimicrobial use in the medical record.

Comparative effectiveness of cefazolin versus cloxacillin as definitive antibiotic therapy for MSSA bacteraemia: results from a large multicentre cohort study

OBJECTIVES We compared the effectiveness of cefazolin versus cloxacillin in the treatment of MSSA bacteraemia in terms of mortality and relapse. METHODS A retrospective cohort study examined consecutive patients with Staphylococcus aureus bacteraemia from six academic and community hospitals between 2007 and 2010. Patients with MSSA bacteraemia who received cefazolin or cloxacillin as the predominant definitive antibiotic therapy were included in the study. Ninety-day mortality was compared between the two groups matched by propensity scores. RESULTS Of 354 patients included in the study, 105 (30%) received cefazolin and 249 (70%) received cloxacillin as the definitive antibiotic therapy. In 90 days, 96 (27%) patients died: 21/105 (20%) in the cefazolin group and 75/249 (30%) in the cloxacillin group. Within 90 days, 10 patients (3%) had a relapse of S. aureus infection: 6/105 (6%) in the cefazolin group and 4/249 (2%) in the cloxacillin group. All relapses in the cefazolin group were related to a deep-seated infection. Based on the estimated propensity score, 90 patients in the cefazolin group were matched with 90 patients in the cloxacillin group. In the propensity score-matched groups, cefazolin had an HR of 0.58 (95% CI 0.31-1.08, P = 0.0846) for 90 day mortality. CONCLUSIONS There was no significant clinical difference between cefazolin and cloxacillin in the treatment of MSSA bacteraemia with respect to mortality. Cefazolin was associated with non-significantly more relapses compared with cloxacillin, especially in deep-seated S. aureus infections.

Linking antimicrobial prescribing to antimicrobial resistance in the ICU: before and after an antimicrobial stewardship program.

Antimicrobials are an effective treatment for many types of infections, but their overuse promotes the spread of resistant microorganisms that defy conventional treatments and complicate patient care. In 2009, an antimicrobial stewardship program was implemented at Mount Sinai Hospital (MSH, Toronto, Canada). Components of this program were to alter the fraction of patients prescribed antimicrobials, to shorten the average duration of treatment, and to alter the types of antimicrobials prescribed. These components were incorporated into a mathematical model that was compared to data reporting the number of patients colonized with Pseudomonas aeruginosa and the number of patients colonized with antimicrobial-resistant P. aeruginosa first isolates before and after the antimicrobial stewardship program. Our analysis shows that the reported decrease in the number of patients colonized was due to treating fewer patients, while the reported decrease in the number of patients colonized with resistant P. aeruginosa was due to the combined effect of treating fewer patients and altering the types of antimicrobials prescribed. We also find that shortening the average duration of treatment was unlikely to have produced any noticeable effects and that further reducing the fraction of patients prescribed antimicrobials would most substantially reduce P. aeruginosa antimicrobial resistance in the future. The analytical framework that we derive considers the effect of colonization pressure on infection spread and can be used to interpret clinical antimicrobial resistance data to assess different aspects of antimicrobial stewardship within the ecological context of the intensive care unit.

Diagnostic Accuracy of Transthoracic Echocardiography for Infective Endocarditis Findings Using Transesophageal Echocardiography as the Reference Standard: A Meta-Analysis

Background: Echocardiography is important for the diagnosis of infective endocarditis (IE), for which transesophageal echocardiography (TEE) is superior to transthoracic echocardiography (TTE). Methods: A systematic review and meta‐analysis of observational studies was performed with the objective of evaluating diagnostic properties of TTE, with transesophageal findings of IE as the reference standard in patients with suspected IE. Results: The literature search yielded 377 unique articles, of which 16 met the inclusion criteria. The 16 studies included 2,807 patients, of whom 793 (28%) had vegetations on TEE. For detecting vegetations, harmonic TTE had sensitivity of 61% (95% CI, 45%–75%) and specificity of 94% (95% CI, 85%–98%) with a negative likelihood ratio (NLR) of 0.42 (95% CI, 0.26–0.61). NLR for harmonic TTE can be improved by including only patients without prosthetic valves (NLR = 0.36; 95% CI, 0.22–0.55) or by having strict criteria for conclusively negative results on TTE (NLR = 0.17; 95% CI, 0.10–0.28). In the setting of patients without prosthetic valves, harmonic TTE had likelihood ratios of 0.14 (95% CI, 0.09–0.23) for a conclusively negative result, 0.66 (95% CI, 0.53–0.81) for an indeterminate result, and 14.60 (95% CI, 3.37–70.40) for a positive result. Conclusions: Modern harmonic TTE still has the potential to miss many vegetations detected on TEE. When limited to patients without prosthetic valves, a conclusively negative TTE under optimal view greatly decreases likelihood of IE. All other transthoracic results are not useful for ruling out IE, and subsequent TEE is almost always required. HighlightsModern harmonic TTE still has the potential to miss many vegetations detected on TEE.Completely normal results on TTE in patients without prosthetic valves can aid in ruling out endocarditis.Any results on TTE other than completely normal require subsequent TEE to rule out endocarditis.

Frailty and Potentially Inappropriate Medication Use at Nursing Home Transition

To estimate the prevalence of potentially inappropriate medication (PIM) use among older adults with cognitive impairment or dementia prior to and following admission to nursing homes and in relation to frailty.