A Multicentre Study about Pattern and Organisms Isolated in Follow-up Blood Cultures / 대한임상미생물학회지

BACKGROUND: This study analysed patterns of requests for repeated blood cultures and the microorganisms isolated in follow-up cultures. METHODS: The frequencies and intervals of repeated blood cultures performed during January and February of 2010 at seven university-affiliated hospitals in Korea were evaluated. Results of microbiological cultures at follow-up were analysed with respect to pathogen replication, immune clearance, appearance of new pathogens, and skin contaminants. RESULTS: Among 3,072 patients who received repeated blood cultures, the average number of requests was 3.2. Of the 5,241 follow-up blood culture events recorded, durations of 1, 2, and 3 days between cultures were identified for 23.1%, 21.4%, and 15.0% of events, respectively. Relative to each initial culture, persistent pathogen growth in subsequent culture(s) accounted for 2.3% of events, whereas immune clearance was confirmed in 8.5% of events. Previously undetected pathogens were isolated in 5.2% of the follow-up cultures, the majority of which grew after an interval of six days. Skin contaminants were detected in 7.6% of the repeated cultures, and 76.1% of the follow-ups displayed no growth of microorganisms. CONCLUSION: The most common numbers of repeat culture requests were two and three, and these were typically performed within three days of the initial culture. Among the follow-up cultures, new pathogens were identified in 5.2%, and the majority of this group likely presented for follow-up during a new disease episode.

Comprehensive Analysis of Blood Culture Performed at Nine University Hospitals in Korea / 대한진단검사의학회지

BACKGROUND: Optimal blood culture performance is critical for successful diagnosis and treatment of sepsis. To understand the status of blood culture, we investigated several aspects of the procedure at 9 university hospitals. METHODS: The process of ordering blood culture sets and sampling volume for adults and children was investigated from January 2010 to April 2010, while the positive rate of detection and growth of skin contaminants were compared in 2009. Microbial growth in aerobic and anaerobic bottles was investigated prospectively. RESULTS: A majority of the hospitals used 2 sets of bottles for adults and 1 bottle for children. The average blood volume in each set was 7.7 mL for adults and 2.1 mL for children. The positive rate of microorganisms was 8.0%, and the isolation rate of the normal flora of the skin was 2.1%. Bacterial growth rates in aerobic and anaerobic bottles only were 31.8% and 24.5% respectively. CONCLUSIONS: Ordering blood culture sets and sampling volumes did not comply with CLSI guidelines. However, the rate of positive cultures and skin contamination rates were acceptable. Anaerobic bottles are useful in enhancing the yield of microorganisms.

Characteristics of Microorganisms Isolated from Blood Cultures at Nine University Hospitals in Korea during 2009 / 대한임상미생물학회지

BACKGROUND: Blood culture is important for determining the etiologic agents of bacteremia and fungemia. Analyses of blood culture results and antimicrobial susceptibility can provide clinicians with relevant information for the empirical treatment of patients. The present study was conducted to assess the frequencies and antimicrobial resistance patterns of clinically important microorganisms from nine hospitals. METHODS: Data including microbiological isolates and corresponding antimicrobial susceptibility test results were collected during 2009 from nine and five university hospitals, respectively. Microorganism identification was based on conventional methods. Antimicrobial susceptibility was tested using the VITEK II system or the Clinical and Laboratory Standards Institute disk diffusion method. RESULTS: Of 397,602 blood specimens cultured from nine hospitals, 34,708 (8.7%) were positive for microorganisms. Excluding coagulase-negative Staphylococci (CoNS), Escherichia coli was the most common isolate (13.5%), followed by Staphylococcus aureus (11.5%), Klebsiella pneumoniae (6.5%) and Enterococcus faecium (3.4%). The isolation rate of CoNS was 23.6%, while that of ceftazidime-resistant E. coli showed geographic differences ranging from 11% to 28%. Among the Gram-negative isolates, A. baumannii displayed the highest levels of resistance. The total isolation rate of the Candida species increased compared to the previous reported rate in Korea. CONCLUSION: Among the isolates, CoNS was the most common, followed by E. coli and S. aureus. The gradual increase in the prevalence of extended-spectrum beta-lactamase (ESBL) producers has contributed to the increase in multi-drug resistance among bacterial isolates from bloodstream infections.