BACKGROUND: Continuous monitoring systems have allowed determination of the time-to-positivity (TTP). We evaluated the clinical relevance of TTP in the BACTEC9240 system (Becton-Dickinson, USA). METHODS: A total of 2,354 vials of positive blood cultures were evaluated over 2 months. TTP was monitored from each of BACTEC Plus Aerobic/F (BD) or Pediatric Plus/F and Lytic Anaerobic/F bottles, and the differential time-to-positivity (DTP) for blood samples drawn simultaneously via catheter and a peripheral site was determined. RESULTS: The average TTP of the positive vials was 17.4 hr, and 79.9% and 95.2% of the vials showed positivity within 24 and 48 hr, respectively. While the average TTP values for Aeromonas hydrophila, Bacillus cereus, Acinetobacter baumannii, and Streptococcus pneumoniae were less than 10 hr, those for Candida spp., anaerobes, Propionibacterium acnes, Corynebacterium spp, Bacillus spp. other than cereus, and coagulase-negative staphylococci were 35.3, 27.0, 56.8, 45.8, 23.0, and 26.3 hr, respectively. The negative predictive values of TTP over 24 hr to predict Staphylococcus aureus among staphylococci and S. pneumoniae among alpha-hemolytic streptococci were 76.7% and 100%, respectively. Enterobacteriaceae and Enterococcus faecalis showed shorter TTP in anaerobic vials than in aerobic vials. DTP of more than 2 hr was observed for 27.8%, 72.2%, and 45.5% of S. aureus, S. epidermidis, and Candida spp. CONCLUSIONS: TTP can be used to discriminate pathogens and contaminants. The shorter TTP in anaerobic vials of certain Enterobacteriaceae and Enterococcus spp. would facilitate further identification. DTP is useful for diagnosing catheter-related bloodstream infection by S. aureus, S. epidermidis, and Candida spp.
Bacteremia/*diagnosis ; Bacteria, Aerobic/isolation &purification ; Bacteria, Anaerobic/isolation &purification ; Bacteriological Techniques/instrumentation/methods ; Humans ; Reagent Kits, Diagnostic ; Time Factors

BACKGROUND: We developed a new disposable anaerobic culture system, namely, the Quick anaero-system, for easy culturing of obligate anaerobes. METHODS: Our system consists of 3 components: 1) new disposable anaerobic gas pack, 2) disposable culture-envelope and sealer, and 3) reusable stainless plate rack with mesh containing 10 g of palladium catalyst pellets. To evaluate the efficiency of our system, we used 12 anaerobic bacteria. We prepared 2 sets of ten-fold serial dilutions of the 12 anaerobes, and inoculated these samples on Luria-Bertani (LB) broth and LB blood agar plate (LB-BAP) (BD Diagnostic Systems, USA). Each set was incubated in the Quick anaero-system (DAS Tech, Korea) and BBL GasPak jar with BD GasPak EZ Anaerobe Container System (BD Diagnostic Systems) at 35-37degrees C for 48 hr. The minimal inoculum size showing visible growth of 12 anaerobes when incubated in both the systems was compared. RESULTS: The minimal inoculum size showing visible growth for 2 out of the 12 anaerobes in the LB broth and 9 out of the 12 anaerobes on LB-BAP was lower for the Quick anaero-system than in the BD GasPak EZ Anaerobe Container System. The mean time (+/-SD) required to achieve absolute anaerobic conditions of the Quick anaero-system was 17 min and 56 sec (+/-3 min and 25 sec). CONCLUSIONS: The Quick anaero-system is a simple and effective method of culturing obligate anaerobes, and its performance is superior to that of the BD GasPak EZ Anaerobe Container System.
Bacteria, Anaerobic/*growth &development ; Bacteriological Techniques/instrumentation/methods ; Culture Media/chemistry ; Gases/chemistry ; Palladium/chemistry ; Reagent Kits, Diagnostic

This study was purposed to investigate the effectiveness of bacterial screening with 24 hours holding in preventing and controlling bacterial contamination of platelets. Bacterial screening of apheresis platelets preserved for 24 hours was performed by using BacT/ALERT automatic bacterial culture system. The samples from 5 bags of platelet were taken in aseptic condition and were merged into 1 bag. The final sample was inoculated into aerobic and anaerobic bottle respectively for testing, meanwhile the screened platelet samples were held for 24 hours. If the platelets were cultured for 24 hours and identification of bacterial strains showed negative, the platelets could be released, and the original platelet samples should be rescreened if initiate positive was found. The results showed that in screening 8017 samples of apheresis platelets the initiate positive results were 16 (0.2%) and confirmed positive were 4 (0.05%). Out of 4 confirmed positive strains, three were Staphylococcus aureus and another was Staphylococcus auricularis. It is concluded that it is necessary for blood center to apply the method of bacterial screening of platelet with 24 hours holding as conventional screening method, which is an effective and feasible way to prevent and control bacterial contamination of platelets.
Bacteria ; isolation & purification ; Bacterial Infections ; prevention & control ; Bacteriological Techniques ; instrumentation ; Blood Platelets ; microbiology ; Blood Preservation ; methods ; standards ; Humans ; Platelet Transfusion ; adverse effects ; Plateletpheresis ; instrumentation

BACKGROUND: Delayed entry of blood culture bottles is inevitable when microbiological laboratories do not operate for 24 hr. There are few studies reported for prestorage of these bottles. The growth dynamics of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were investigated with respect to various preincubation conditions. METHODS: Fifteen or 150 colony-forming units (CFU) of bacteria were inoculated into standard aerobic or anaerobic blood culture bottles. Bottles were preincubated at 25degrees C or 37degrees C for 0, 2, 4, 8, 12, 24, or 48 hr. The time to detection (TTD) then was monitored using the BacT/Alert 3D system (bioMerieux Inc., USA). RESULTS: Significant difference in TTD was observed following preincubation for 8 hr at 25degrees C vs. 4 hr at 37degrees C for S. aureus, 4 hr at 25degrees C vs. 4 hr at 37degrees C for E. coli, 12 hr at 25degrees C vs. 4 hr at 37degrees C for P. aeruginosa, compared to no preincubation (P<0.005). TTD values did not vary significantly with bacterial CFU or with aerobic or anaerobic bottle type. The BacT/Alert 3D system returned false negatives following preincubation of P. aeruginosa for 48 hr at 25degrees C or 24 hr at 37degrees C. CONCLUSIONS: TTD was mainly affected by preincubation temperature and duration rather than by input CFU quantity or bottle type for the 3 experimental bacteria.
Bacteriological Techniques/instrumentation/*methods ; Culture Media ; Escherichia coli/growth & development/*isolation & purification ; Pseudomonas aeruginosa/growth & development/*isolation & purification ; Staphylococcus aureus/growth & development/*isolation & purification ; Temperature ; Time Factors

In this study, our self-made micro-electrical impedance sensors and experimental apparatus were used to measure the impedance of bacteria-inoculated medium. Then the bacteria in the culture of all values obtained during the period were recorded into the trace impedance curve. Seeing the obvious difference in morphological change, we utilized the differed impedance curves in an attempt to estimate the morphological difference between the drug sensitivity of bacteria. The studies of clinical medicine for achieving rapid drug sensitivity test, automation and intelligentization of drug sensitivity are of practical significance.
Anti-Bacterial Agents ; pharmacology ; Bacteria ; drug effects ; growth & development ; Bacteriological Techniques ; instrumentation ; methods ; Electric Impedance ; Escherichia coli ; drug effects ; growth & development ; Microbial Sensitivity Tests ; methods ; Salmonella ; drug effects ; growth & development