Model to evaluate the impact of hospital-based interventions targeting false-positive blood cultures on economic and clinical outcomes

BACKGROUND

Blood culture contamination (BCC) increases length of stay (LOS) and leads to unnecessary antimicrobial therapy and/or hospital-acquired conditions (HACs).

AIM

To quantify the magnitude of additional LOS, costs to hospitals and society, and harm to patients attributable to BCC.

METHODS

A retrospective matched survival analysis was performed involving hospitalized patients with septicaemia-compatible symptoms. BCC costs, HACs and potential savings were calculated based on the primary LOS data, a modified Delphi process and published sources. The cost analysis compared standard care with interventions for reducing BCC, and estimated annual economic and clinical consequences for a typical hospital and for the USA as a whole.

FINDINGS

Patients with BCC experienced a mean increase in LOS of 2.35 days (P=0.0076). Avoiding BCC would decrease costs by $6463 [$4818 from inpatient care (53% of which was from reduced LOS) and 26% from reduced antibiotic use]. Annually, in a typical 250- to 400-bed hospital, employing phlebotomists would save $1.3 million and prevent 24 HACs (including two cases of Clostridium difficile infection); based on clinical efficacy evidence, use of the studied initial specimen diversion device (ISDD) would save $1.9 million and prevent 34 HACs (including three cases of C. difficile infection). In the USA, the respective strategies would prevent 69,300 and 102,900 HACs (including 6000 and 8900 cases of C. difficile infection) and save $5 and $7.5 billion.

CONCLUSION

Costs and clinical burdens associated with false-positive cultures are substantial and can be reduced by available interventions, including phlebotomists and use of ISDD.

Evaluation of blood culture epidemiology and efficiency in a large European teaching hospital

Background

Blood cultures remain the gold standard for detecting bacteremia despite their limitations. The current practice of blood culture collection is still inefficient with low yields. Limited focus has been given to the association between timing of specimen collection at different time points during admission and their yield.

Methods

We carried out a retrospective observational study by analyzing all 3,890 sets of cultures collected from the 1,962 admitted patients over the seven-month period of this study. We compared the blood culture yield between the early group (≤24 hours after admission) and the late group (> 24 hours of admission). We also investigated the effect of prehospital oral antibiotics and pre-analytical time on the first cultures in the emergency department. Epidemiology and efficiency of blood cultures were studied for each medical specialty.

Results

In total, 3,349(86.1%) blood cultures were negative and 541(13.9%) were positive for one or more microorganisms. After correcting for contamination, the overall yield was 290 (7.5%). The early group (n = 1,490) yielded significantly more true-positive cultures (10.1% versus 5.8%, P<0.001) than the late group (n = 2,400). The emergency department had a significantly higher yield than general wards, 11.2% versus 5.7% (p<0.001). Prehospital oral antibiotic use and pre-analytical time did not affect the yield of first cultures at the emergency department (p = 0.735 and 0.816 respectively). The number of tests needed to obtain one true-positive culture varied between departments, ranging from 7 to 45.

Conclusion

This study showed that blood cultures are inefficient in detecting bacteremia. Cultures collected during 24 hours after admission yielded more positive results than those collected later. Significant variations in blood culture epidemiology and efficiency per specialty suggest that guidelines should be reevaluated. Future studies should aim at improving blood culture yield, implementing educational programs to reduce contamination and cost-effective application of modern molecular diagnostic technologies.

Sepsis and septic shock: Pathogenesis and treatment perspectives

The majority of bacteremias do not develop to sepsis: bacteria are cleared from the bloodstream. Oxygen released from erythrocytes and humoral immunity kill bacteria in the bloodstream. Sepsis develops if bacteria are resistant to oxidation and proliferate in erythrocytes. Bacteria provoke oxygen release from erythrocytes to arterial blood. Abundant release of oxygen to the plasma triggers a cascade of events that cause: 1. oxygen delivery failure to cells; 2. oxidation of plasma components that impairs humoral regulation and inactivates immune complexes; 3. disseminated intravascular coagulation and multiple organs' failure. Bacterial reservoir inside erythrocytes provides the long-term survival of bacteria and is the cause of ineffectiveness of antibiotics and host immune reactions. Treatment perspectives that include different aspects of sepsis development are discussed.

Etiology of septicemia in children with acute leukemia: 9-year experience from a children's hospital in China

Bloodstream infection is an important cause of death among leukemia patients, and the etiologic agent surveillance is important for the prophylaxis and treatment. This study aims to identify the common bloodstream isolates in hospitalized leukemia patients with septicemia in our hospital, to choose the ideal combination of antimicrobial agents for infection prophylaxis and to clarify the appropriate time for antibiotic prophylaxis. To know this information, a retrospective analysis was conducted over a 9-year period from July 2001 to July 2010 by reviewing medical records of leukemia children admitted to our hospital. The overall frequencies of isolation were 45% in Gram-positive bacteria, 53.8% in Gram-negative bacteria, and 1.2% in fungi, respectively. Coagulase-negative Staphylococci were the most common organisms isolated, accounting for 32.7% of the total blood culture isolates, followed by Escherichia coli (15.7%) and Klebsiella pneumoniae (7.1%). The incidence of septicemia caused by extended-spectrum β-lactamase-producing E. coli and K. pneumoniae was high (69.2% and 58.8% of total isolates, respectively). The coverage rate of antimicrobial combinations of "vancomycin+cefoperazone-sulbactam" and "vancomycin+piperacillin-tazobactam" to blood culture isolates of leukemia patients in our hospital were 91.88% and 90.27%, respectively. More than 90% of septicemia occurred when the absolute neutrophil count was lower than 1.6×10⁹/L and 83.05% when absolute neutrophil count was lower than 1.0×10⁹/L. These results suggest that ongoing surveillance for antimicrobial susceptibility in leukemia children remains essential. Vancomycin+cefoperazone-sulbactam and vancomycin+piperacillin-tazobactam are the good choice for leukemia children to prevent bacterial infections in our hospital. In an effort to reduce total consumption of antibiotics and to elevate the therapeutic efficacy, antibiotics prophylaxis should be started with the appearance of neutropenia in leukemia children.