The Clinical Significance of Positive Blood Cultures in the 1990s: A Prospective Comprehensive Evaluation of the Microbiology, Epidemiology, and Outcome of Bacteremia and Fungemia in Adults

Abstract

To assess changes since the mid-1970s, we reviewed 843 episodes of positive blood cultures in 707 patients with septicemia. The five most common pathogens were Staphylococcus aureus, Escherichia coli, coagulase-negative staphylococci (CNS), Klebsiella pneumoniae, and Enterococcus species. Although CNS were isolated most often, only 12.4% were clinically significant. Half of all episodes were nosocomial, and a quarter had no recognized source. Leading identifiable sources included intravenous catheters, the respiratory and genitourinary tracts, and intraabdominal foci. Septicemia-associated mortality was 17.5%. Patients who received appropriate antimicrobial therapy throughout the course of infection had the lowest mortality (13.3%). Multivariate analysis showed that age (relative risk [RR], 1.80), microorganism (RR, 2.27), source of infection (RR, 2.86), predisposing factors (RR, 1.98), blood pressure (RR, 2.29), body temperature (RR, 2.04), and therapy (RR, 2.72) independently influenced outcome. Bloodstream infections in the 1990s are notable for the increased importance of CNS as both contaminants and pathogens, the proportionate increase in fungi and decrease in anaerobes as pathogens, the emergence of Mycobacterium avium complex as an important cause of bacteremia in patients with advanced human immunodeficiency virus infection, and the reduction in mortality associated with infection.

Antimicrobial stewardship without infectious disease physician

“…Thus, information on the prognosis of these five patients who received no antifungal treatment in the preintervention group is important. Moreover, assessing the clinical significance of candidemia, as in a previous study,2 would help to interpret the results of this study. Finally, the initial sentence in the Primary Outcome section of the Results is incorrect.…”

“…If these five patients survived at discharge without antifungal treatment, five (16.7%) of 30 patients with candidemia were considered not to have true candidemia that required treatment. This means that the clinical judgment not to treat for candidemia in these patients was appropriate, although most candida isolated from positive blood cultures reflects true candidemia 2. However, given that no gold standard exists for differentiating pathogens from contaminants,3 it is interesting that 16.7% of patients with candidemia were managed without any antifungal treatment.…”

Predicting bacteremia based on nurse‐assessed food consumption at the time of blood culture

“…If only 1 set of blood cultures was acquired and was positive for a pathogenic organism (such as enteric Gram-negative bacilli or Streptococcus pneumonia) that could account for the clinical presentation, then the culture was considered positive. 7,14,15 Definition of Contamination We considered as contaminants organisms common to skin flora, including Bacillus species, coagulase-negative staphylococci, Corynebacterium species, and Micrococcus species, without isolation of an identical organism with the same antibiotic susceptibilities from another potentially infected site in a patient with incompatible clinical features and no attributable risks. 16 Single blood cultures positive for organisms thought unlikely to explain the patient's symptoms were also considered contaminants.…”

“…6 Positive blood cultures can demonstrate not only an infectious cause of disease but also the microbiological response to antibiotic therapy. 7 However, studies have reported that 35% to 50% of positive blood cultures are falsely positive owing to contamination. [7][8][9][10][11] False-positive cultures may lead to the use of inappropriate or unnecessary antibiotics, additional testing and consultation, and prolonged hospitalizations that increase patient care costs.…”

“…7 However, studies have reported that 35% to 50% of positive blood cultures are falsely positive owing to contamination. [7][8][9][10][11] False-positive cultures may lead to the use of inappropriate or unnecessary antibiotics, additional testing and consultation, and prolonged hospitalizations that increase patient care costs. 9,12 Nursing staff caring for patients are generally able to assess oral intake, general clinical state, and care requirements.…”