|Year : 2016 | Volume
| Issue : 3 | Page : 401-403
Analysis of samples processed in automated blood culture system with blood culture samples processed by conventional manual method
V Gautam1, K Saigal2, V Awasthy3, P Ray1
1 Department of Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India
3 BD Diagnostic Systems, Gurgaon, Haryana, India
|Date of Submission||20-Apr-2015|
|Date of Acceptance||29-Jan-2016|
|Date of Web Publication||12-Aug-2016|
Department of Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Gautam V, Saigal K, Awasthy V, Ray P. Analysis of samples processed in automated blood culture system with blood culture samples processed by conventional manual method. Indian J Med Microbiol 2016;34:401-3
|How to cite this URL:|
Gautam V, Saigal K, Awasthy V, Ray P. Analysis of samples processed in automated blood culture system with blood culture samples processed by conventional manual method. Indian J Med Microbiol [serial online] 2016 [cited 2020 Jan 28];34:401-3. Available from: http://www.ijmm.org/text.asp?2016/34/3/401/188379
Automated blood cultures are currently performed with continuous-monitoring blood culture systems.  Postgraduate Institute of Medical Education and Research is a public sector hospital with the largest turnover of automated blood culture system (ABCS) services available. The public sector has grown slowly with many complexities limiting the paradigm shift toward automation. Thus, the aim of this study was to evaluate the results of ABCS and compare same with the manual method, in a public sector tertiary care hospital.
A retrospective study of all specimens sent for blood culture from patients with suspected septicemia were evaluated. By conventional blood culture system (CBCS) (tryptone soy broth and bile broth [Hi-Media Labs, India]) data were collected from August 2008 to July 2009. By ABCS (BACTEC Standard/10 Aerobic/F vial or a BACTEC Peds Plus/F medium bottle, BACTEC 9240 [Becton Dickinson]) data were collected from February 2010 to January 2011. The different parameters studied were organism distribution, the rate of positivity, average time to detection/turnaround time, and contamination rate.
Total of 23,197 samples were subjected to CBCS. Among 16.3% samples which were positive, 1.9% (437/23,153) of samples showed contamination and thus the true positivity rate detected by conventional system was 14.3% (3340/23,197). By ABCS total of 28,784 samples were processed. Of 19.6% samples which were positive, 3.9% (1131/28,766) samples showed growth of contaminants and thus true positivity rate by the automated system was 15.7% (4523/28,766) [Table 1]. Recovery of Gram-positive organisms was more as compared to Gram-negatives using ABCS. With the help of ABCS yeast could be reported at least 48 h earlier than CBCS. A SDA plate with chloramphenicol was used to subculture positive flagged automated blood culture bottles and it increased the yield of detection of Candida spp. in our study. Fastidious organisms such as Streptococcus pneumoniae, Haemophilus influenzae, Sterotrophomonas maltophiliai were identified using ABCS. This was in concordance with earlier studies reporting ABCS have an added advantage for detection of certain fastidious organisms. , Organisms such as Brucella spp. Borrelia spp. and Shigella flexeneri which are known to cause bacteremia and were never reported in the last 40 years of our experience with conventional blood culture method was also isolated.
|Table 1: Distribution of various organisms in conventional method and automated blood culture systems |
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Around 75.6% of our samples were positive within 24 h with the use of ABCS while 65.4% samples detected by CBCS were positive after the second subculture and around 12.6% samples were positive after the third subculture. The first report was dispatched in 93 h and 36 min using CBCS and by ABCS within 52 h and 48 min. A provisional report was provided on the basis of Gram-staining of positive flagged bottles detected by ABCS. On an average initial provisional report was available by 28 h and 48 min, reducing the time of reporting by 64 h and 48 min. With the use of ABCS final reporting time was reduced by 40 h and 48 min (i.e., by ~ 2 days).
The most common contaminants identified were diptheroids and coagulase-negative staphylococci. Contamination rate by ABCS (3.9%) was much higher. The sensitivity of ABCS is more so even miniscule amount of contamination could be picked up. Thus, strict criteria's should be followed for blood collection when using ABCS in our settings.
The main advantages of ABCS over CBCS as noted were shorter turnaround time to detect pathogens, considerable labor savings, and improved laboratory workflow. In hospital settings where resistance profiles of circulating micro-organisms are known, the use of rapid identifying method helps to guide empiric antimicrobial usage to improve patient outcomes.
We would like to acknowledge the support provided by BD Diagnostic Systems, India for this study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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