Staphylococcus aureus bacteremia among patients with health care-associated fever

Bandemia as an Early Predictive Marker of Bacteremia: A Retrospective Cohort Study

This single-center retrospective observational study aimed to verify whether a diagnosis of bandemia could be a predictive marker for bacteremia. We assessed 970 consecutive patients (median age 73 years; male 64.8%) who underwent two or more sets of blood cultures between April 2015 and March 2016 in both inpatient and outpatient settings. We assessed the value of bandemia (band count > 10%) and the percentage band count for predicting bacteremia using logistic regression models. Bandemia was detected in 151 cases (15.6%) and bacteremia was detected in 188 cases (19.4%). The incidence of bacteremia was significantly higher in cases with bandemia (52.3% vs. 13.3%; odds ratio (OR) = 7.15; 95% confidence interval (CI) 4.91–10.5). The sensitivity and specificity of bandemia for predicting bacteremia were 0.42 and 0.91, respectively. The bandemia was retained as an independent predictive factor for the multivariable logistic regression model (OR, 6.13; 95% CI, 4.02–9.40). Bandemia is useful for establishing the risk of bacteremia, regardless of the care setting (inpatient or outpatient), with a demonstrable relationship between increased risk and bacteremia. A bandemia-based electronic alert for blood-culture collection may contribute to the improved diagnosis of bacteremia.

Spatially Targeted Proteomics of the Host-Pathogen Interface during Staphylococcal Abscess Formation

Staphylococcus aureus is a common cause of invasive and life-threatening infections that are often multidrug resistant. To develop novel treatment approaches, a detailed understanding of the complex host-pathogen interactions during infection is essential. This is particularly true for the molecular processes that govern the formation of tissue abscesses, as these heterogeneous structures are important contributors to staphylococcal pathogenicity. To fully characterize the developmental process leading to mature abscesses, temporal and spatial analytical approaches are required. Spatially targeted proteomic technologies such as micro-liquid extraction surface analysis offer insight into complex biological systems including detection of bacterial proteins and their abundance in the host environment. By analyzing the proteomic constituents of different abscess regions across the course of infection, we defined the immune response and bacterial contribution to abscess development through spatial and temporal proteomic assessment. The information gathered was mapped to biochemical pathways to characterize the metabolic processes and immune strategies employed by the host. These data provide insights into the physiological state of bacteria within abscesses and elucidate pathogenic processes at the host-pathogen interface.

Screening for dental focal infections in febrile patients with hematologic malignancies who received chemotherapy: a retrospective cohort study

Source of fever in chemotherapy patients is often unknown. Fever can also be fatal. No observational studies have determined the incidence of dental focal infection (DFI)-associated fever, despite oral cavity being a potential source of infection. We report the incidence of fever after chemotherapy in patients with hematological malignancies and their association with DFIs in 441 patients visiting our institution during a 6-year period. Dental treatments, including tooth extraction, were performed, and their oral and hematological profiles were monitored after chemotherapy. Fever was evident in 87 (38.5%) of 226 patients (≥ 38˚C) after the first cycle of chemotherapy. Sepsis due to DFIs (n = 4; 4.6%) was evaluated. Chemotherapy was delayed due to DFI in one case. Fever after chemotherapy should be differentiated from oral infections. Our study emphasizes the significance of DFI in patients with fever after chemotherapy and can help in improving the prognosis of patients.

Risk of bacteremia in patients presenting with shaking chills and vomiting - a prospective cohort study

Chills and vomiting have traditionally been associated with severe bacterial infections and bacteremia. However, few modern studies have in a prospective way evaluated the association of these signs with bacteremia, which is the aim of this prospective, multicenter study. Patients presenting to the emergency department with at least one affected vital sign (increased respiratory rate, increased heart rate, altered mental status, decreased blood pressure or decreased oxygen saturation) were included. A total of 479 patients were prospectively enrolled. Blood cultures were obtained from 197 patients. Of the 32 patients with a positive blood culture 11 patients (34%) had experienced shaking chills compared with 23 (14%) of the 165 patients with a negative blood culture, P = 0.009. A logistic regression was fitted to show the estimated odds ratio (OR) for a positive blood culture according to shaking chills. In a univariate model shaking chills had an OR of 3.23 (95% CI 1.35–7.52) and in a multivariate model the OR was 5.9 (95% CI 2.05–17.17) for those without prior antibiotics adjusted for age, sex, and prior antibiotics. The presence of vomiting was also addressed, but neither a univariate nor a multivariate logistic regression showed any association between vomiting and bacteremia. In conclusion, among patients at the emergency department with at least one affected vital sign, shaking chills but not vomiting were associated with bacteremia.

Do Bacteremic patients with end-stage renal disease have a fever when presenting to the emergency department? A paired, retrospective cohort study

Background

Fever is a common symptom when patients present to Emergency Departments. It is unclear if the febrile response of bacteremic hemodialysis-dependent patients differs from bacteremic patients not receiving hemodialysis. The objective of this study was to compare Emergency Departments triage temperatures of patients with and without hemodialysis-dependent end-stage rental disease who have Staphylococcus aureus bacteremia and determine the incidence of afebrile S. aureus bacteremia.

Methods

Paired, retrospective cohort study of 37 patients with and 37 patients without hemodialysis hospitalized with Methicillin-resistant or Methicillin-susceptible S. aureus bacteremia. Emergency Department triage temperatures were reviewed for all patients, as were potential confounding variables.

Results

54% (95% CI, 38–70%) and 82% (95% CI 65–91%) of hemodialysis and non-hemodialysis patients did not have a detectable fever (<100.4 °F) at triage. Triage temperatures were 100.5 °F (95% CI 99.9–101.2 °F) and 99.0 °F (95% CI 98.4–99.6 °F) in the hemodialysis and non-hemodialysis cohorts, respectively (p < 0.001). Triage temperature in patients with and without diabetes mellitus was 99.2 °F (95% CI 98.4–99.9 °F) and 100.4 °F (95% CI 99.7–101.0 °F), respectively (p = 0.03). We were unable to detect a significant effect of diabetes mellitus and other potential confounding variables on differences in temperature between the hemodialysis and non-hemodialysis cohorts (all interactions p > 0.19).

Conclusions

Hemodialysis-dependent patients with S. aureus bacteremia had significantly higher temperatures than non- hemodialysis-dependent end stage renal disease patients but more than half of patients were without detectable fever at triage, possibly reflecting use of insensitive methods for measuring temperature. Absence of fever at presentation to the Emergency Department should not delay blood culture acquisition in patients who are at increased risk of S. aureus bacteremia.

Emerging Technologies for Molecular Diagnosis of Sepsis

Rapid and accurate profiling of infection-causing pathogens remains a significant challenge in modern health care. Despite advances in molecular diagnostic techniques, blood culture analysis remains the gold standard for diagnosing sepsis. However, this method is too slow and cumbersome to significantly influence the initial management of patients. The swift initiation of precise and targeted antibiotic therapies depends on the ability of a sepsis diagnostic test to capture clinically relevant organisms along with antimicrobial resistance within 1 to 3 h. The administration of appropriate, narrow-spectrum antibiotics demands that such a test be extremely sensitive with a high negative predictive value. In addition, it should utilize small sample volumes and detect polymicrobial infections and contaminants. All of this must be accomplished with a platform that is easily integrated into the clinical workflow. In this review, we outline the limitations of routine blood culture testing and discuss how emerging sepsis technologies are converging on the characteristics of the ideal sepsis diagnostic test. We include seven molecular technologies that have been validated on clinical blood specimens or mock samples using human blood. In addition, we discuss advances in machine learning technologies that use electronic medical record data to provide contextual evaluation support for clinical decision-making.

Best Clinical Practice: Blood Culture Utility in the Emergency Department

BACKGROUND

Bacteremia affects 200,000 patients per year, with the potential for significant morbidity and mortality. Blood cultures are considered the most sensitive method for detecting bacteremia and are commonly obtained in patients with fever, chills, leukocytosis, focal infections, and sepsis.

OBJECTIVE

We sought to provide emergency physicians with a review of the literature concerning blood cultures in the emergency department.

DISCUSSION

The utility of blood cultures has been a focus of controversy, prompting research evaluating effects on patient management. Bacteremia is associated with increased mortality, and blood cultures are often obtained for suspected infection. False-positive blood cultures are associated with harm, including increased duration of stay and cost. This review suggests that blood cultures are not recommended for patients with cellulitis, simple pyelonephritis, and community-acquired pneumonia, because the chance of a false-positive culture is greater than the prevalence of true positive cultures. Blood cultures are recommended for patients with sepsis, meningitis, complicated pyelonephritis, endocarditis, and health care-associated pneumonia. Clinical prediction rules that predict true positive cultures may prove useful. The clinical picture should take precedence. If cultures are obtained, two bottles of ≥7 mL should be obtained from separate peripheral sites.

CONCLUSIONS

Blood cultures are commonly obtained but demonstrate low yield in cellulitis, simple pyelonephritis, and community-acquired pneumonia. The Shapiro decision rule for predicting true bacteremia does show promise, but clinical gestalt should take precedence. To maximize utility, blood cultures should be obtained before antibiotic therapy begins. At least two blood cultures should be obtained from separate peripheral sites.

Peripheral Venous Catheter-Related Staphylococcus aureus Bacteremia

Objective.

Better understand the incidence, risk factors, and outcomes of peripheral venous catheter (PVC)-related Staphylococcus aureus bacteremia.

Design.

Retrospective study of PVC-related S. aureus bacteremias in adult patients from July 2005 through March 2008. A point-prevalence survey was performed January 9, 2008, on adult inpatients to determine PVC utilization; patients with a PVC served as a cohort to assess risk factors for PVC-related S. aureus bacteremia.

Setting.

Tertiary care teaching hospital.

Results.

Twenty-four (18 definite and 6 probable) PVC-related S. aureus bacteremias were identified (estimated incidence density, 0.07 per 1,000 catheter-days), with a median duration of catheterization of 3 days (interquartile range, 2-6). Patients with PVC-related S. aureus bacteremia were significantly more likely to have a PVC in the antecubital fossa (odds ratio [OR], 6.5), a PVC placed in the emergency department (OR, 6.0), or a PVC placed at an outside hospital (P = .005), with a longer duration of catheterization (P < .001). These PVCs were significantly less likely to have been inserted in the hand (OR, 0.23) or placed on an inpatient medical unit (OR, 0.17). Mean duration of antibiotic treatment was 19 days (95% confidence interval, 15-23 days); 42% (10/24) of cases encountered complications. We estimate that there may be as many as 10,028 PVC-related S. aureus bacteremias yearly in US adult hospitalized inpatients.

Conclusion.

PVC-related S. aureus bacteremia is an underrecognized complication. PVCs inserted in the emergency department or at outside institutions, PVCs placed in the antecubital fossa, and those with prolonged dwell times are associated with such infections.

Repeat endocarditis: analysis of risk factors based on the International Collaboration on Endocarditis - Prospective Cohort Study

Repeat episodes of infective endocarditis (IE) can occur in patients who survive an initial episode. We analysed risk factors and 1-year mortality of patients with repeat IE. We considered 1874 patients enrolled in the International Collaboration on Endocarditis - Prospective Cohort Study between January 2000 and December 2006 (ICE-PCS) who had definite native or prosthetic valve IE and 1-year follow-up. Multivariable analysis was used to determine risk factors for repeat IE and 1-year mortality. Of 1874 patients, 1783 (95.2%) had single-episode IE and 91 (4.8%) had repeat IE: 74/91 (81%) with new infection and 17/91 (19%) with presumed relapse. On bivariate analysis, repeat IE was associated with haemodialysis (p 0.002), HIV (p 0.009), injection drug use (IDU) (p < 0.001), Staphylococcus aureus IE (p 0.003), healthcare acquisition (p 0.006) and previous IE before ICE enrolment (p 0.001). On adjusted analysis, independent risk factors were haemodialysis (OR, 2.5; 95% CI, 1.2-5.3), IDU (OR, 2.9; 95% CI, 1.6-5.4), previous IE (OR, 2.8; 95% CI, 1.5-5.1) and living in the North American region (OR, 1.9; 95% CI, 1.1-3.4). Patients with repeat IE had higher 1-year mortality than those with single-episode IE (p 0.003). Repeat IE is associated with IDU, previous IE and haemodialysis. Clinicians should be aware of these risk factors in order to recognize patients who are at risk of repeat IE.

Shaking chills and high body temperature predict bacteremia especially among elderly patients

Purposes

The difference in predictors of bacteremia between elderly and non-elderly patients is unclear despite the aging of society. The objective was to determine predictors of bacteremia among elderly patients aged 80 years and older compared to non-elderly patients aged 18 to 79 years.

Methods

A referral hospital-based retrospective descriptive study from April 2012 to March 2013 in Okinawa, Japan. All enrolled patients were adults suspected of having bacterial infection who had been newly admitted into the Division of Infectious Diseases. HIV- infected patients were excluded. Exposures were a history of shaking chills, prior antibiotics use within 48 hours, vital signs, and laboratory inflammation markers on admission. Outcome was blood culture positivity.

Results

Three hundred and sixty-six patients were enrolled. Median age was 78.5 (interquartile range [IQR]: 62–88). Among patients aged 18 to 79 years, shaking chills (adjusted odds ratio [AOR] 2.22, 95% confidence interval [CI]: 1.09–4.51) and previous antibiotics use (AOR 0.08, 95% CI: 0.01–0.68) were significant. However, among patients aged 80 years and older, shaking chills (AOR 3.06, 95% CI: 1.30–7.19) and body temperature above 38.5°C (AOR 2.98, 95% CI: 1.30–6.83) were significant.

Conclusions

A history of shaking chills and vital signs indicating high body temperature were two findings that were useful in predicting bacteremia, especially in elderly patients aged 80 years and older. Further study is needed to assess whether the result is applicable in other regions and populations.

A risk stratification model of acute pyelonephritis to indicate hospital admission from the ED

OBJECTIVES

There are no guidelines regarding the hospitalization of female patients with acute pyelonephritis (APN); therefore, we performed a retrospective analysis to construct a clinical prediction model for hospital admission.

METHODS

We conducted a retrospective analysis of a prospective database of women diagnosed as having APN in the emergency department between January 2006 and June 2012. Independent risk factors for admission were determined by multivariable logistic regression analysis in half of the patients in this database. The risk of admission was categorized into 5 groups. The internal and external validations were conducted using the remaining half of the patients and 192 independent patients, respectively.

RESULTS

Independent risk factors for admission were age of 65 years or greater (odds ratio [OR], 2.62; 1 point), chill (OR, 2.40; 1 point), and the levels of segmented neutrophils greater than 90% (OR, 2.00; 1 point), serum creatinine greater than 1.5 mg/dL (OR, 2.41; 1 point), C-reactive protein greater than 10 mg/dL (OR, 2.37; 1 point), and serum albumin less than 3.3 g/dL (OR, 7.36; 2 points). The admission risk scores consisted of 5 categories, which were very low (0 points; 5.9%), low (1 point; 10.7%), intermediate (2 points; 20.7%), high (3-4 points; 51.9%), and very high (5-7 points; 82.8%) risk, showing an area under the curve of 0.770. The areas under the curve of the internal and external validation cohorts were 0.743 and 0.725, respectively.

CONCLUSION

This model can provide a guideline to determine the admission of women with APN in the emergency department.

The impact of healthcare-associated infection on mortality: failure in clinical recognition is related with inadequate antibiotic therapy

PURPOSE

To understand if clinicians can tell apart patients with healthcare-associated infections (HCAI) from those with community-acquired infections (CAI) and to determine the impact of HCAI in the adequacy of initial antibiotic therapy and hospital mortality.

METHODS

One-year prospective cohort study including all consecutive infected patients admitted to a large university tertiary care hospital.

RESULTS

A total of 1035 patients were included in this study. There were 718 patients admitted from the community: 225 (31%) with HCAI and 493 (69%) with CAI. Total microbiologic documentation rate of infection was 68% (n = 703): 56% in CAI, 73% in HCAI and 83% in hospital-acquired infections (HAI). Antibiotic therapy was inadequate in 27% of patients with HCAI vs. 14% of patients with CAI (p<0.001). Among patients with HCAI, 47% received antibiotic therapy in accordance with international recommendations for treatment of CAI. Antibiotic therapy was inadequate in 36% of patients with HCAI whose treatment followed international recommendations for CAI vs. 19% in the group of HCAI patients whose treatment did not follow these guidelines (p = 0.014). Variables independently associated with inadequate antibiotic therapy were: decreased functional capacity (adjusted OR = 2.24), HCAI (adjusted OR = 2.09) and HAI (adjusted OR = 2.24). Variables independently associated with higher hospital mortality were: age (adjusted OR = 1.05, per year), severe sepsis (adjusted OR = 1.92), septic shock (adjusted OR = 8.13) and inadequate antibiotic therapy (adjusted OR = 1.99).

CONCLUSIONS

HCAI was associated with an increased rate of inadequate antibiotic therapy but not with a significant increase in hospital mortality. Clinicians need to be aware of healthcare-associated infections among the group of infected patients arriving from the community since the existing guidelines regarding antibiotic therapy do not apply to this group and they will otherwise receive inadequate antibiotic therapy which will have a negative impact on hospital outcome.

Additional risk factors for infection by multidrug-resistant pathogens in healthcare-associated infection: a large cohort study

BACKGROUND

There is a lack of consensus regarding the definition of risk factors for healthcare-associated infection (HCAI). The purpose of this study was to identify additional risk factors for HCAI, which are not included in the current definition of HCAI, associated with infection by multidrug-resistant (MDR) pathogens, in all hospitalized infected patients from the community.

METHODS

This 1-year prospective cohort study included all patients with infection admitted to a large, tertiary care, university hospital. Risk factors not included in the HCAI definition, and independently associated with MDR pathogen infection, namely MDR Gram-negative (MDR-GN) and ESKAPE microorganisms (vancomycin-resistant Enterococcus faecium, methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella species, carbapenem-hydrolyzing Klebsiella pneumonia and MDR Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species), were identified by logistic regression among patients admitted from the community (either with community-acquired or HCAI).

RESULTS

There were 1035 patients with infection, 718 from the community. Of these, 439 (61%) had microbiologic documentation; 123 were MDR (28%). Among MDR: 104 (85%) had MDR-GN and 41 (33%) had an ESKAPE infection. Independent risk factors associated with MDR and MDR-GN infection were: age (adjusted odds ratio (OR) = 1.7 and 1.5, p = 0.001 and p = 0.009, respectively), and hospitalization in the previous year (between 4 and 12 months previously) (adjusted OR = 2.0 and 1,7, p = 0.008 and p = 0.048, respectively). Infection by pathogens from the ESKAPE group was independently associated with previous antibiotic therapy (adjusted OR = 7.2, p < 0.001) and a Karnofsky index <70 (adjusted OR = 3.7, p = 0.003). Patients with infection by MDR, MDR-GN and pathogens from the ESKAPE group had significantly higher rates of inadequate antibiotic therapy than those without (46% vs 7%, 44% vs 10%, 61% vs 15%, respectively, p < 0.001).

CONCLUSIONS

This study suggests that the inclusion of additional risk factors in the current definition of HCAI for MDR pathogen infection, namely age >60 years, Karnofsky index <70, hospitalization in the previous year, and previous antibiotic therapy, may be clinically beneficial for early diagnosis, which may decrease the rate of inadequate antibiotic therapy among these patients.

Development of a vaccine against Staphylococcus aureus

A vaccine to prevent infections caused by Staphylococcus aureus would have a tremendously beneficial impact on public health. In contrast to typical encapsulated bacterial pathogens, such as Streptococcus pneumoniae, H. influenzae, and Neisseria meningitides, the capsule of S. aureus is not clearly linked to strain virulence in vivo. Furthermore, it is not clear that natural infection caused by S. aureus induces a protective humoral immune response, as does infection caused by typical encapsulated bacteria. Finally, pure B cell or antibody deficiency, in either animal models or in patients, does not predispose to more frequent or more severe S. aureus infections, as it does for infections caused by typical encapsulated bacteria. Rather, primary immune mechanisms necessary for protection against S. aureus infections include professional phagocytes and T lymphocytes (Th17 cells, in particular) which upregulate phagocytic activity. Thus, it is not clear whether an antibody-mediated neutralization of S. aureus virulence factors should be the goal of vaccination. Rather, the selection of antigenic targets which induce potent T cell immune responses that react to the broadest possible array of S. aureus strains should be the focus of antigen selection. Of particular promise is the potential to select antigens which induce both humoral and T cell-mediated immunity in order to generate immune synergy against S. aureus infections. A single-antigen vaccine may achieve this immune synergy. However, multivalent antigens may be more likely to induce both humoral and T cell immunity and to induce protection against a broader array of S. aureus isolates. A number of candidate vaccines are in development, raising the promise that effective vaccines against S. aureus will become available in the not-so-distant future. Possible development programs for such vaccines are discussed.