Detection of bacteria and fungi in BacT/Alert standard blood-culture bottles
Department of Clinical Laboratory Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan. Journal of Infection and Chemotherapy
(Impact Factor: 1.49).
10/2003; 9(3):227-32. DOI: 10.1007/s10156-003-0245-7
Incubation periods of aerobic (AE) and anaerobic (AN) blood-culture bottles with the BacT/Alert system were assessed in our laboratory. We reviewed the results of 6229 blood-culture sets collected at Kyoto University Hospital from January 1999 to December 2000. Of these sets, 731 (11.7%) were positive for bacteria or yeast. Excluding 87 sets with growth evidence on arrival, of the 644 positive blood-culture sets from 341 patients, a total of 691 organisms were isolated. Of the 691 organisms, 413 (59.8%) were recovered from both bottles, 206 (29.8%) were recovered only from the AE bottle, and 72 (10.4%) were recovered only from the AN bottle. The AE bottle was significantly superior to the AN bottle in terms of both recovery rate and detection time for overall organisms, but there was no significant difference in detection time for facultative anaerobic bacteria between the two bottles. Of the 691 organisms, 530 (76.7%) were classified as usual pathogens. Of the 530 usual pathogens, 501 (94.5%) were recovered in at least one bottle of each set within the first 3 days, and 523 (98.7%) within the first 5 days of incubation. Twenty-nine organisms initially isolated on day 4 or later were recovered from 19 patients. Of these, chart reviews indicated that 21 organisms recovered from 11 patients were considered clinically significant bacteria, and the reviews also revealed that no patient had a treatment plan altered based on the results of positive blood culture. Seven organisms initially isolated on day 6 or later were recovered from 7 patients. Chart reviews revealed that 5 of these organisms from 5 patients were considered to be clinically significant. In conclusion, if the incubation period had been less than 3 days, 11 patients with clinically significant bacteremia or fungemia, (3.2% of all patients with bacteremia or fungemia) would have been undiagnosed. Similarly, with an incubation period of 5 days, 5 such patients (1.5%) would have been undiagnosed.
Available from: Sang-Min Lee
- "Several authors have reported that they cultured blood for more than 5 days to identify specific slowgrowing organisms. Therefore, it has been suggested that the appropriate duration for blood culture should be determined on an individual basis according to the clinical relevance of the culture (29, 30). A prospective study would have avoided this methodological weakness. "
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ABSTRACT: The aim of this study was to determine candidemia incidence among patients in a medical intensive-care unit (MICU) and the associated mortality rate and to identify risk factors associated with candidemia. We retrospectively performed a 1:3 matched case-control study of MICU patients with candidemia. Controls were matched for sex, age, and Acute Physiology and Chronic Health Evaluation (APACHE) II score. Candidemia incidence was 9.1 per 1,000 admissions. The most common pathogen was Candida albicans. Crude mortality was 96% among candidemia patients and 52% among controls (P<0.001). Mortality differed significantly between the groups according to Kaplan-Meier survival analysis (P=0.024). Multivariate analysis identified the following independent risk factors for candidemia: central venous catheterization (odds ratio [OR] = 3.2, 95% confidence interval [CI]=1.2-9.0), previous steroid therapy (OR=4.7, 95% CI=1.8-12.1), blood transfusion during the same admission period (OR=6.3, 95% CI=2.4-16.7), and hepatic failure upon MICU admission (OR=6.9, 95% CI=1.7-28.4). In conclusion, we identify an additional independent risk factor for candidemia, the presence of hepatic failure on MICU admission. Therefore, increased awareness of risk factors, including hepatic failure, is necessary for the management of candidemia.
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ABSTRACT: To elucidate the existence of microorganisms from blood culture bottles in hospitals without a microbiology laboratory, we changed the system of blood culture examinations. The Oxoid signal blood culture system and submission of all blood cultures to the clinical testing industry was used from July 2002 to December 2002 (first period). Use of the BacT/Alert system and performing of Gram stain for positive culture bottles in our institutions was conducted from January 2003 to June 2003 (latter period). A total of 210 and 193 blood cultures were processed during the first and latter periods, respectively. There were 40 (19.0%) positive cultures in the first period and 32 (16.6%) positive cultures in the latter period. The times from the specimen collection to the Gram stain result that were required were 3.8 and 1.0 days in the first period and the latter period, respectively. The times required for the final report of the blood cultures in the first period and in the latter period were 5.8 and 4.9 days, respectively. We conclude that using a continuous monitoring, automated blood culture system and performing Gram stain for positive culture bottles in institutions without microbiology laboratories may be useful for medical doctors to rapidly determine the existence of microorganisms and to begin adequate antiinfective therapy.
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