Joshua Greg Garcia
PMLS01BM
Assignment
What is/are the common skin normal flora that causes a contamination in blood cultures?
Hall & Lyman (2006) cited from several studies that coagulase-negative staphylococci are the most
common blood culture contaminants responsible for around 70% − 80% contaminated blood cultures,
as supported by a molecular analysis of Viagappan & Kelsey (1995) implying that coagulase-negative
staphylococcal contaminants came from the patient’s own skin flora. Another common skin flora
responsible for contamination of blood samples is corynebacterium species (Weinstein, 2003).
Various common normal skin flora can also be located on the blood itself, in which contaminated
blood culture samples should be differentiated from blood samples indicating bacteremia (Bates & Lee,
1992) whereas identifying the source of microbe/bacteria would determine if the results either indicate
contamination or presence of bacteremia (Schifman et al., 1998) which may include staphylococcus
aureus, streptococcus pneumoniae, escherichia coli (E. coli), pseudomonas aeruginosa, and candida
albicans (Weinstein et al. 1997). In addition, skin antisepsis minimizes normal skin flora but it cannot be
based to differentiate contamination from bacteremia as Hall & Lyman (2006) cited from studies that even
with skin antisepsis, normal skin flora may survive disinfection as determined through culturing skin
samples collected using a sterile surgical technique but because antiseptics cannot penetrate deep layers
of the skin where some of the mentioned normal skin flora can be located, various studies concluded that
inadequate skin preparation is thought to be the most common cause of blood culture contamination.
References
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