Reassessment of the incubation time in a controlled clinical comparison of the BacT/Alert aerobic FAN bottle and standard anaerobic bottle used aerobically for the detection of bloodstream infections

This study assessed the minimum incubation time required to detect bloodstream infections during a controlled clinical comparison of the performance characteristics of the BacT/Alert aerobic FAN bottle and the standard anaerobic bottle used aerobically except on a selective basis. Blood was collected from adults with suspected bloodstream infections and inoculated into each bottle, which was monitored in the BacT/Alert Microbial Detection System. The anaerobic bottle was vented before incubation except when cultures were obtained from patients on the colorectal and gynecologic surgical and emergency services. Statistical analysis was limited to those culture sets in which each bottle was inoculated with ≥8 mL of blood and bacterial growth was considered to be clinically significant. A total of 682 positive cultures from 243 patients satisfied the inclusion criteria. Significantly more isolates of Staphylococcus aureus (p <0.001), S. epidermidis (p <0.001), other coagulase-negative staphylococci (p <0.001), Enterococcus spp. (p = 0.04), Escherichia coli (p = 0.03), all Enterobacteriaceae (p <0.001), Pseudomonas aeruginosa (p = 0.001), and Candida spp. (p <0.001) were detected by the aerobic FAN bottle. Significantly more septic episodes due to S. aureus, S. epidermidis, other coagulase-negative staphylococci, Enterobacteriaceae, P. aeruginosa, and Candida spp. were detected by the aerobic FAN bottle. Significantly more bacterial isolates were detected by the aerobic FAN whether or not antibiotics were being administered at the time of blood culture, whereas there were significantly fewer positive cultures in the vented standard anaerobic bottle when patients were receiving antimicrobial therapy than when they were not. All but 5% of positive cultures were detected within three days. Only six of the cultures requiring four or five days of incubation represented true misses, and only one of these six resulted in a change in therapy which, however, did not affect the patent’s outcome.     

Assessment of the FAN anaerobic bottle for culture of continuous ambulatory peritoneal dialysis fluid using the BacT/Alert system

The purpose of this study was to determine if the newly available FAN anaerobic bottle (FANAN) alone would be comparable to the combination of the FAN aerobic (FANAE) plus the standard BacT/Alert anaerobic (REGAN) bottles for culture of continuous ambulatory peritoneal dialysis (CAPD) fluid from patients with CAPD peritonitis. CAPD fluid (10 mL) was injected into each bottle, which was then monitored by the BacT/Alert instrument by using a 7-day protocol. Aerobic and anaerobic terminal subculture were performed on all bottles before they were classified as being culture negative.There were 181 effluents received that were suitable for analysis. Growth was detected in 76 (42%) effluents by at least one method. FANAE was the single best medium detecting 84/96 (88%) of all organisms whereas the FANAN and REGAN each detected 69/96 (72%). The combination of FANAE and REGAN bottles detected 92/96 (96%) isolates, which was significantly better than the FANAN or FANAE alone for isolate recovery (p < 0.001). The isolates that were missed by the FANAN but that were recovered by either FANAE or REGAN were all facultative anaerobes commonly detected in CAPD fluids. Terminal subculture revealed otherwise undetected pathogens in 3.9% of positive effluents, usually Pseudomonas aeruginosa.Based on our data, FANAE was the single best bottle for detection of CAPD peritonitis and, in combination with an anaerobic bottle, detected growth from the most effluents. FANAN alone could not substitute for the FANAE/REGAN combination. Although terminal subculture remains controversial, we recommend routine aerobic subculture to ensure that no P. aeruginosa isolates are missed.     

Comparative study of BacT/alert FAN bottles and standard BacT/alert bottles

A total of 5,230 paired blood cultures were studied. One sample was divided between aerobic and anaerobic BacT/Alert standard bottles, and the other divided between aerobic and anaerobic BacT/Alert FAN bottles. There were 44 occasions where Staphylococcus aureus was recovered only from the FAN bottles, compared to six where only the standard bottles were positive (p <0.001), and 21 occasions where Escherichia coli was isolated only from FAN bottles, compared to eight occasions where only the standard bottles were positive for this organism (p <0.05). In 21 of 28 cases reviewed where S. aureus was isolated from FAN bottles only the patient had been receiving anti-staphylococcal antibiotics. However, only 2 of 30 cases where Gram-negative bacilli were isolated from FAN bottles had documented recent appropriate antibiotic therapy. Patients in whom FAN bottles are more likely to recover organisms cannot be selected on the basis of documented antibiotic treatment.     

Evaluation of BACTEC Plus aerobic and anaerobic blood culture bottles and BacT/Alert FAN aerobic and anaerobic blood culture bottles for the detection of bacteremia in ICU patients

Blood culture is the most valuable laboratory test for the diagnosis of bacteremia and sepsis. The BACTEC FX and BacT/Alert 3D automated blood culture systems are commonly used in Korean health care facilities. A controlled clinical evaluation of the resin-containing BACTEC Plus aerobic (BA) and anaerobic (BN), and the charcoal-containing FAN aerobic (FA) and anaerobic (FN) bottles using blood from intensive care unit (ICU) patients was designed. The performances of these 2 systems with media containing particle absorbing antimicrobial agents were evaluated using the culture positivity rate and time to detection (TTD). TTD was collected using data management systems, either the Epicenter (BD Diagnostic Systems) or the hospital laboratory information system. A total of 1539 four-bottle sets were collected from 270 patients in medical and surgical ICUs. Blood culture samples included 1539 bottles each of BA, BN, FA, and FN, and yielded 113 (7.3%), 90 (5.8%), 104 (6.8%), and 80 (5.2%) positive bacterial or fungal isolates, respectively. There were significant differences between the resin-containing BA and BN samples in culture positivity and also between the charcoal-containing FA and FN samples, especially for Escherichia coli (25/27 versus 17/27, P < 0.05) and Acinetobacter baumannii (14/15 versus 7/15, P < 0.05). Significantly shorter recovery time was observed in BACTEC Plus aerobic bottles than in FAN aerobic bottles (17.2 and 24.7 h, respectively) (P < 0.001).     

两种需氧血培养系统对模拟菌血症检测能力的比较

目的比较BACTEC PLUS树脂需氧瓶与BacT／Alert FA活性炭需氧瓶对模拟菌血症的检测能力。方法选择烧伤科常用的抗生素与细菌病原体，将菌液、抗生素、新鲜无菌血注入各培养瓶内，记录5d内阳性瓶的检出时间及二者对万古霉素的吸附能力，对2种具有不同吸附剂的血培养瓶的阳性检出率及平均检出时间进行比较。结果除替考拉宁组外，BACTEC PLUS树脂需氧瓶的细菌阳性检出率和平均检出时间均优于BacT／Alert FA活性炭需氧瓶，差异有统计学意义（P〈0．001）；替考拉宁组BacT／Alert FA活性炭需氧瓶的细菌阳性检出率和平均检出时间优于BACTEC PLUS树脂需氧瓶。结论在进行血培养时，应该尽可能在抗生素使用以前或F次使用抗生素以前采血。对已经应用抗生素的患者，应选择具有中和、吸附抗生素能力的培养系统。     

Bactec FX和Bact/Alert 3D两种血培养系统对菌血症的检出性能分析

目的对比分析Bactec FX血培养系统Bactec Plus树脂需氧瓶(简称BO-P瓶)和Bact/Alert 3D全自动血培养系统SA标准瓶(简称Bio-SA瓶)/SN厌氧瓶(简称Bio-SN瓶)对菌血症的检出能力及特点,探讨提高血培养阳性率、快速准确地作出病原学诊断的方法。方法从双侧部位抽取患者的静脉血,一侧注入BO-P瓶,另一侧注入Bio-SA瓶和Bio-SN瓶,置于相应培养系统培养,比较这3种血培养瓶的阳性率及检出时间。结果 6 188份标本中确认阳性765份(12.36%);确认污染134份(2.17%);假阳性11份(0.18%)。332株临床分离菌中BO-P瓶检出293例,占88.25%;Bio-SA瓶检出271例,占81.63%,前者阳性率高于后者(χ2=5.687,P<0.05);Bio-SN瓶检出201例,占60.54%,其中厌氧菌3例,占0.90%。与Bio-SA瓶相比,BO-P瓶检出阳性的时间优于Bio-SA瓶(P<0.05),尤其是对非发酵菌。污染菌以革兰阳性菌为主(89.55%),主要是凝固酶阴性的葡萄球菌(67.91%),少部分革兰阴性杆菌(9.7%)。结论双侧抽血并联合使用Bactec FX和Bact/Alert 3D血培养系统可利用各自优势,更有效地提高血培养阳性率。     

Evaluation of the BacT/Alert microbial detection system with FAN aerobic and FAN anaerobic bottles for culturing normally sterile body fluids other than blood

We evaluated the BacT/Alert Microbial Detection System (Organon Teknika Corporation, Durham, NC, USA) by using FAN bottles compared to conventional culture methods for the recovery of microorganisms from normally sterile body fluids other than blood and dialysates. Clinically significant pathogens were isolated from 116 (11%) of 1, 099 consecutive specimens (80 from both conventional media and FAN bottles; 23 from FAN bottles only; 13 from conventional media only). Gram-positive cocci were more likely to be recovered from FAN bottles than from conventional media (p = 0.04). Contaminants were also more likely to have grown in FAN bottles (3%) than on conventional media (1%) (p = 0.04). The mean time to detection of significant pathogens was 20.9 h using FAN bottles as compared to 30. 9 h using conventional media (p = 0.0001). These results indicate that the BacT/Alert Microbial Detection System using FAN blood culture bottles improves the yield of clinically significant Gram-positive isolates from normally sterile body fluids with a reduced time to detection.     

Predominance of Enterobacteriaceae Isolates in Early Positive Anaerobic Blood Culture Bottles in BacT/Alert System

We collected and analyzed the time to detection (TTD) of blood cultures in the BacT/Alert automated system from 2002 to 2007. Among the 10,893 monomicrobial isolates from a total of 133,735 blood culture sets, the recoveries of aerobic bottles were compared with those of anaerobic bottles in this study. Significantly more Gram‐positive cocci (except Staphylococcus aureus and enterococci), glucose nonfermentative Gram‐negative bacteria, and yeast were recovered from aerobic bottles than from anaerobic bottles. The average TTD was 19.0 hr and 20.1 hr for the aerobic and anaerobic bottles, respectively, and 96.8% of the microorganisms were detected within the first 72 hr. Of the 5,489 microorganisms recovered from both of the blood culture bottle pair, microbial growth was significantly more often detected first in the anaerobic bottles than the aerobic bottles for Enterobacteriaceae except Serratia marcescens, while S. aureus, coagulase‐negative staphylococci and Pseudomonas aeruginosa were more often detected first in the aerobic bottles. According to these data, we conclude that the earlier positivity of anaerobic bottles is a useful marker for rapid presumptive identification of Enterobacteriaceae infection. J. Clin. Lab. Anal. 27:113–120, 2013. © 2013 Wiley Periodicals, Inc.     

Clinical comparison of the Bactec Mycosis IC/F, BacT/Alert FA, and BacT/Alert FN blood culture vials for the detection of candidemia

The present study analyzed the performance of Bactec Mycosis IC/F, BacT/Alert FA, and BacT/Alert FN vials in detection and time to detection (TTD) of Candida spp. in 179 simultaneous blood cultures. The Mycosis IC/F, BacT/Alert FA, and BacT/Alert FN vials could detect Candida spp. in 144 (80.45%) of 179, 149 (83.24%) of 179, and 8 (4.47%) of 179 samples, respectively. With the presence of antifungal therapy, the numbers of positive vials were higher in BacT/Alert FA compared to Mycosis IC/F, 87/99 versus 73/99, respectively (P < 0.05). TTD (SD) for C. albicans was shorter in Mycosis IC/F than in BacT/Alert FA vials without antifungal therapy, 20.89 (9.33) versus 28.26 (9.77), respectively (P < 0.01). The detection of Candida spp., with concomitant bacteremia, was higher in Mycosis IC/F than in BacT/Alert FA vials, 28/30 and 19/30, respectively (P = 0.01). The present data show that the use of Bactec Mycosis IC/F together with BacT/Alert FA vials might improve the detection of Candida spp.     

Difference in time to positivity of hub-blood versus nonhub-blood cultures is not useful for the diagnosis of catheter-related bloodstream infection in critically ill patients.

OBJECTIVE: The differential time to positivity (DTTP), defined as the difference in time necessary for the blood cultures taken by a peripheral puncture and through the catheter to become positive has been suggested to be useful in differentiating between catheter-related bloodstream infection (CR-BSI) and other sources of bacteremia. A DTTP of >120 mins was found predominantly in CR-BSI. The objective of our study was to investigate whether DTTP is useful for the diagnosis of CR-BSI in a medical-surgical intensive care unit. DESIGN: Prospective clinical study. SETTING: A 60-bed medical-surgical intensive care unit of a university hospital. PATIENTS: One hundred consecutive adult patients from whom catheter(s) were to be removed for suspected CR-BSI were studied. INTERVENTION: A blood culture (using aerobic and anaerobic culture bottles) was first taken from a new puncture site. Next, a blood culture was taken through every intravascular catheter in place. MEASUREMENTS AND RESULTS: DTTP was calculated using the automated BacT/Alert blood culture system. Three patients had CR-BSI and nine patients had noncatheter-related bacteremia. Five patients had catheter-related sepsis without proven bacteremia. There was no significant difference in median DTTP between patients with CR-BSI and noncatheter-related bacteremia (2.1 hrs and 3.3 hrs, respectively; p =.6). Moreover, catheter-related sepsis in patients without bacteremia could not be detected using DTTP. CONCLUSION: DTTP seems not to be useful for the diagnosis of CR-BSI in a medical-surgical intensive care unit.     

Clinical comparison of the BACTEC 9000 Standard Anaerobic/F and Lytic/F blood culture media

An 8-month prospective, volume controlled, comparison of Standard Anaerobic/F media with a new anaerobic high blood volume lytic medium (Lytic/F) was performed. A total of 2,092 compliant sets, consisting of an aerobic resin bottle or standard aerobic bottle, Standard Anaerobic/F, and Lytic/F bottle were evaluated. A total of 220 (10.6%) positive specimens were detected from the paired anaerobic bottles. These consisted of 194 true positive and 26 false positive bottles. Of 207 total organisms isolated, 122 were considered clinically significant. A comparison of significant organism recovery revealed 79 isolates in both anaerobic bottles, 7 isolates in the standard Anaerobic/F bottle only, and 36 isolates in the Lytic/F bottle only (p < 0.001). The Lytic/F bottle detected significantly more Enterobacteriaceae (p < 0.005) and Streptococci (p < 0.05). There were 24 false positive Standard Anaerobic/F bottles and 2 false positive Lytic/F bottles (p < 0.001). When both bottles were positive the Standard Anaerobic/F bottle was positive 12 hours earlier in 1 instance whereas the Lytic/F bottle was positive 12 hours earlier in 8 instances. The mean time for detection in the Standard Anaerobic/F bottle was 18.2 hours versus 13.2 hours for the Lytic/F bottle.The new Lytic/F anaerobic blood culture media was found to be superior to Standard Anaerobic/F media for both total organism recovery and time to organism detection.     

Bacterial detection in apheresis platelets: blood systems experience with a two-bottle and one-bottle culture system

BACKGROUND: United Blood Services (UBS) began bacterial testing of platelets (PLTs) using one‐bottle cultures in September 2003. Collection of 7‐day PLTs using two‐bottle cultures began in April 2006. This study compares our experience using both systems. STUDY DESIGN AND METHODS: PLTs from 13 UBS regional centers cultured from September 1, 2003, to September 1, 2007, were included in the analysis. Positive‐signal bottles from a commercially available microbial detection system (BacT/ALERT, bioMérieux) were sent, with corresponding PLTs if available, for confirmatory testing using plate culture media. AABB definitions were used with modifications. RESULTS: A total of 51,265 7‐day PLT collections and 191,521 5‐day PLT collections were tested with bacterial cultures. The overall true‐positive (TP) rate for the two‐bottle system (1:8544) was comparable to the TP rate with the previous one‐bottle system (1:6344). In three of six yield cases, only the anaerobic bottle was positive (two cases of Group D Streptococci, one case of Corynebacterium spp.). The false‐positive (FP) and indeterminate (IND) rates in the anaerobic bottle (1:1767 and 1:1830, respectively) were significantly higher than those in the aerobic bottle (1:6408 and 1:17,088, respectively; p < 0.001). One confirmed transfusion‐related septic reaction, classified as a late TP after investigation, was reported out of 242,786 tested PLT donations. CONCLUSION: The rate of TP cases by the two‐bottle system was not increased over the one‐bottle system, although anaerobic‐bottle‐only positive cases were detected. FP and IND rates were increased in the two‐bottle system, attributable to the anaerobic bottle. Observation of only one documented transfusion‐related septic reaction in 4 years of bacterial screening at UBS is reassuring, although limitations in passive surveillance and higher rates of reactions reported by others indicate the need for continued vigilance.     

The use of the arterial line as a source for blood cultures

OBJECTIVE: To determine the reliability of blood cultures obtained through indwelling arterial lines as compared to that of blood cultures obtained by venipuncture. DESIGN: A prospective observational study. SETTING: Six-bed mixed medical surgical intensive care unit (ICU) of a 550-bed university-affiliated medical center. MEASUREMENTS: During a 3-month period blood culture sets, when clinically indicated, were drawn in parallel from indwelling arterial catheters and one-time venipuncture and the results compared. Each blood sample consisted of 15 ml and was distributed equally between three blood culture bottles: aerobic, anaerobic and one aerobic resin-containing bottle. Blood culture results from the two sources were compared according to preset definitions. MAIN RESULTS: During the study period 90 parallel blood culture sets (540 bottles) were obtained from 36 patients. Forty-three (16%) venipuncture bottles were positive versus 88 (32%) arterial line culture bottles (p < 0.001). Of the parallel sets, 83% yielded equivalent results - either both sterile or both growing the same organism. Amongst the discordant sets, the arterial line cultures grew 37 gram-positive and 18 gram-negative isolates not found in venipuncture sets (i.e. 50% of 109 arterial line isolates), while only two gram-positive isolates were solely grown in venipuncture cultures (4% of all 55 venipuncture isolates, p < 0.001). On clinical correlation, all the gram-positive organisms in the discordant cultures were found not to reflect bacteremia, while five of the 18 gram-negative isolates (28%) grown only in arterial line cultures probably did reflect ongoing bacteremia. CONCLUSION: The results of blood cultures taken from the arterial line are frequently equivalent to those taken from venipuncture. When discordant, the growth of gram-positive bacteria almost certainly reflects contamination or arterial line colonization, whereas the growth of gram-negative bacteria may have to be considered as reflecting bacteremia.     

The performance of 4 different supplements and 5 blood culture bottles types in detection of bacteria and Candida spp. in simulated sterile body fluid cultures

The purpose of this investigation was to evaluate the performance of 4 supplements: horse blood, fastidious organisms supplement (FOS), haemin isovitalex albumine (HIA), and brain heart infusion–haemin isovitalex albumine (BHI-HIA) and 5 blood culture bottles: Bactec Mycosis IC/F, Plus Aerobic/F, Peds Plus/F from the Bactec 9240 system, and BacT/Alert FA and BacT/Alert PF from the BacT/Alert 3D system, in detection of bacteria and Candida spp. in simulated sterile body fluids other than blood models. In total, 8 reference strains (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, Listeria monocytogenes, Candida albicans, and Candida parapsilosis) and 11 clinical bacteria and yeast isolates (6 isolates from cerebrospinal fluid and 5 isolates from blood) were included in this study. Horse blood, FOS, and HIA were significantly better than no supplements (P < 0.0001, P < 0.0002, and P = 0.05, respectively) in detection of bacteria. Interestingly, there was no significant difference between BHI-HIA and bottles without any supplements. Sixty bottles analyzed of which 59 (98.33%) bottles with horse blood, 53 (88.33%) with FOS, 45 (75.00%) with HIA, and 43 (71.67%) with BHI-HIA signaled positive. The positivity rates with horse blood were significantly higher than with HIA and BHI-HIA (P < 0.0005 and P < 0.0001, respectively). Similarly, the blood culture bottles with horse blood had shorter time to detection (TTD) compared to bottles with FOS and HIA (P < 0.05 and P < 0.0001, respectively). When yeasts were analyzed, almost all (124/125) blood culture bottles with Candida spp. signaled positive even in the absence of supplements. Bactec Mycosis IC/F had significantly shorter TTD compared to Bactec Peds Plus/F, Bactec Plus Aerobic/F, BacT/Alert FA, and BacT/Alert PF bottles in detection of Candida spp. (P < 0.005, P < 0.05, P < 0.001, and P < 0.001, respectively). The present study showed that horse blood was the most effective supplement in growth of bacteria in the blood culture bottles that were analyzed in the study.     

Can BacT/Alert FA and FN blood culture bottles increase the recovery of microorganisms in the clinical laboratory?

To evaluate whether the use of BacT/Alert FA and FN blood culture bottles increases the yield of microorganisms, we performed a before–after study. BacT/Alert standard aerobic (AE) and anaerobic (AN) bottles were used from January 1999 to May 2001 (before period). FA and FN bottles were used from May 2001 to March 2003 (after period). A total of 7796 AE, 7807 AN, 4798 FA, and 4787 FN bottles were processed. There were 742 (9.5%) AE-, 598 (7.7%) AN-, 521 (10.7%) FA-, and 396 (8.3%) FN-positive bottles. From these positive bottles 776, 631, 585, and 487 microorganisms were isolated, respectively. Among the isolated microorganisms, 58 (7.5%) and 59 (10.1%) Candida species were isolated from AE and FA bottles, respectively, and 17 (2.7%) and 21 (4.3%) obligate anaerobes were isolated from AN and FN bottles, respectively. We conclude that BacT/Alert FA and FN bottles showed a higher percentage of positivity for microorganisms, in particular for Candida species and obligate anaerobes.     

Initial detection of bacteremia by subculture of unvented tryptic soy broth blood culture bottles

Routine subculture of macroscopically negative blood cultures is a traditional blood culture procedure. The need to perform routine early (6-17 hr) and late (48 hr) subculture of unvented blood culture bottles when a simultaneous subculture of the vented bottle is performed has been questioned. Blood cultures in paired vented and unvented tryptic soy broth (TSB) bottles from 4574 patients were examined retrospectively. Subculture of unvented TSB bottles provided initial detection of 412 (5.0%) isolates from 277 (6.1%) patients and was comparable to that of vented TSB bottles for Pseudomonas and all other microorganisms, except for the Enterobacteriaceae (p less than 0.001; vented TSB), Candida (p less than 0.001; vented TSB), and Haemophilus influenzae (p less than 0.01; unvented TSB). Of the H. influenzae isolates, 46% were detected initially by subculture of the unvented TSB bottles; early subculture recovered 67% of these isolates. The value of subculture of unvented TSB bottles is minimized when subculture of the vented TSB bottle is routinely performed; however, routine subculture of the unvented bottle is recommended whenever TSB is used for detection of bacteremia in patients in whom H. influenzae infection is possible.     

Validation of BacT/ALERT plastic culture bottles for use in testing of whole-blood-derived leukoreduced platelet-rich-plasma-derived platelets

BACKGROUND: Bacterial detection of platelet (PLT)-rich-plasma (PRP)-derived PLTs presents unique challenges for countries that do not allow pooling before storage. This study validated the BacT/ALERT for use in testing pooled PRP-derived PLTs with nine contaminating organisms. STUDY DESIGN AND METHODS: Isolates of Bacillus cereus, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis, Serratia marcescens, Streptococcus viridans, and Propionibacterium acnes were inoculated into two PRP-derived PLT pools (target, 10 and 100 colony-forming units [CFUs]/mL; actual recovered concentrations, 5 and 90 CFUs/mL). Four milliliters of each postbacterial inoculation sample was inoculated into both plastic aerobic and anaerobic bottles and 0.5 mL was plated onto blood agar. RESULTS: All organisms (excluding P. acnes) were detected in 8.2 to 22.0 and 7.6 to 20.3 hours (10 and 100 CFUs/mL, respectively) and the mean time to detection was 15.0 and 13.1 hours (10 and 100 CFUs/mL, respective). P. acnes was detected with the anaerobic bottles in a mean of 74.9 and 64.3 hours (10 and 100 CFUs/mL, respectively). With E. cloacae, E. coli, K. pneumoniae, S. marcescens, and S. viridans detection with the anaerobic bottles was faster or equivalent to the detection with the aerobic bottles. This was most notable with S. viridans where the anaerobic bottle was reactive on average 21.6 and 10.8 hours (10 and 100 CFUs/mL, respectively) faster than the aerobic bottle. CONCLUSIONS: This study validates the use of the BacT/ALERT system for the detection of bacteria in PRP-derived PLTs in a pooled format. Overall, the use of the BacT/ALERT system allowed the detection of pooled PRP-derived PLTs inoculated with nine bacteria at 10 and 100 CFUs per mL in 7.6 to 22.0 hours (excluding P. acnes).     

Factors affecting microbial contamination rate of cord blood collected for transplantation

BACKGROUND: Collection and processing of cord blood (CB) is associated with significant risk of microbial contamination and hence relevant standards mandate microbial screening of the final product. This study aimed to determine the contamination rate and associated risk factors during 14 years of banking at the Sydney Cord Blood Bank. STUDY DESIGN AND METHODS: CB was collected and processed using a closed system and tested for contamination using blood culture bottles (BacT/ALERT, bioMérieux) incubated for a minimum of 5 days. Four microbial screening methods were used with different combinations of inoculated bottles (adult or pediatric) and associated sample volumes (10 or 1 mL). RESULTS: Of 13,344 CB units screened, 537 (4.0%) tested positive for contamination, with Bacteroides spp. (20.9%), Staphylococcus spp. (18.6%), and Propionibacterium spp. (13.7%) being the most common isolates. The contamination rate reduced from 10% in 1997 to 1.1% in 2009. Multivariate analysis demonstrated the following variables were independently associated with higher contamination rates: vaginal delivery, collection by obstetric staff, and use of an anaerobic bottle in addition to an aerobic bottle (which facilitated a larger sample inoculation volume than pediatric bottles). CONCLUSIONS: This study demonstrates that contamination rates of CB collected for transplantation can be substantially reduced by collection after cesarean delivery and utilizing trained CB collection staff. These data also indicate that the common practice of testing using a pediatric (aerobic) bottle with its attendant small volume of the final CB product may be suboptimal for sensitive detection of contaminating anaerobic microbes.     

The utility of anaerobic blood culture in detecting facultative anaerobic bacteremia in children

Routine anaerobic blood culture is not recommended in children because obligate anaerobic bacteremia is rare in the pediatric population. However, a number of facultative anaerobic bacteria can cause community and hospital acquired infections in children and the utility of anaerobic blood culture for detection of these organisms is still unclear. We conducted a retrospective analysis of all blood culture samples (n = 24,356) at a children’s hospital in Japan from October 2009 to June 2012. Among the samples that had paired aerobic and anaerobic blood cultures, 717 samples were considered clinically significant with 418 (58%) organisms detected from both aerobic and anaerobic cultures, 167 (23%) detected only from aerobic culture and 132 (18%) detected only from anaerobic culture. While most facultative anaerobes were detectable by aerobic culture, over 25% of Enterobacteriaceae and 15% of Staphylococcus sp. were detected from anaerobic cultures bottles only, suggesting its potential role in selected settings.     

Detection of bacteria and fungi in BacT/Alert standard blood-culture bottles

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.