08/2014 December 2014

Best Practices in Blood Culture Collection

Newsletter

Sterile Fluids in

Blood Culture Bottles

Whenever the subject of blood culture is discussed, the intend-

ed sample type used is always related to blood sample fully. However,

we need to also be aware that other than blood sample, sterile fluids

can also be inoculated as sample for blood culture testing. Among the

sterile fluids that are commonly known are peritoneal, pleural, syno-

vial, cerebrospinal, pericardial, amniotic etc. [1]

The presence of microorganism recovered from sterile fluids is

potentially life-threatening specifically for the case of meningitis, peri-

carditis, peritonitis, septic arthritis and empyema.[2] Therefore, it is

of paramount importance to be able to get recovery and identifica-

tion of such microorganisms so that early treatment can be initiated.

Customarily in the laboratory workflow, sterile fluid is routinely

cultured onto solid culture medium (chocolate agar and blood agar

for cerebrospinal fluid, aerobic and anaerobic media for peritoneal

fluid) or more preferably with an enrichment broth medium.[2] More

often than not, the solid culture might take up to 30 days to recover

the microorganism eg: Brucella melitensis. Not only that, there are

also additional challenges of microorganism recovery in sterile fluids

which [1]:

a. Low number of microorganism even though with large volume of

specimens;

b. Low volume of sample eg: CSF and synovial fluids;

c. Initiation of antibiotic therapy before collection of sample which lead to

the false negative results;

d. Fastidious organisms may be missed if proper media or supplements are

not incorporated into the culture method;

e. Contaminant microorganisms may overgrow potential pathogens;

f. Delay in transport of the specimen to the microbiology laboratory may

result in decreased recovery.

The use of blood culture system for culture of normal sterile fluid is

gaining increasing acceptance. Based on a study using BACTEC 9240 Blood

Culture System to detect Brucella melitensis in synovial fluid, it is able to re-

cover 3 of 14 positive cultures(21.4%) by day 3, 7 of 14 positive cultures

(50%) by day 4, 12 of 14 positive cultures(85.7%) by day 5 and all 14 positive

cultures(100%) by day 7[3]. Another study did by F.Z Akcam et. al., 2006 us-

ing BACTEC blood culture system, 139(15.3%) of 906 specimens were isolat-

ed by both the BACTEC blood culture system and conventional culture,

whereas 80(8.8%) specimens were isolated by BACTEC blood culture system

only. In another word, BACTEC blood culture system is able to increase isola-

tion of bacteria undetectable by conventional method by 8.8%[2].

In conclusion, blood culture is one way to detect bacterial infection in

sterile fluid sample by with higher sensitivity. By using BACTEC blood culture,

studies have proven that it is able to handle the challenges faced by conven-

tional method.

Towards-Better-Lives

REFERENCES

1. DeAnna D. Fuller, Thomas E.Davis. Comparison of BACTEC Plus Aerobic/F,

Anaerobic/F, Peds Plus/F, and Lytic/F Media with and without Fastidious

Organism Supplement to Conventional Methods for Culture of Sterile Body

Fluids. DIAG MICROBIOL INFECT DIS 1997:; 29:219-225.

2. F.Z. Akcam et al. Evaluation of Bactec microbial detection system for cul-

turing miscellaneous sterile body fluids. Research in Microbiology 157

(2006) 433-436.

3. P. Yagupsky et al. 2001. Use of BACTEC 9240 Blood Culture System for De-

tection of Brucella melitensis in Synovial Fluid. J. Clin. Microbiol. 39.2.738-

739.

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