From the Research
Gram-positive cocci in chains are common contaminants in clinical specimens, occurring in approximately 2-5% of blood cultures, and their presence should be interpreted with caution, considering the clinical context and collection technique 1.
Contamination Rates
The contamination rates of gram-positive cocci in chains vary by collection technique, with higher rates seen in samples collected through existing intravenous lines (up to 10-15%) compared to direct venipuncture (1-3%) 1.
- Collection technique is a significant factor in contamination rates
- Proper skin antisepsis and sterile technique can minimize contamination
- Clinical context and patient symptoms should be considered when interpreting laboratory results
Clinical Context
Laboratory interpretation should consider the clinical context, as the same organism can represent either contamination or true infection depending on patient symptoms, risk factors, and the number of positive cultures 2.
- Patient symptoms and risk factors should be evaluated
- Multiple blood cultures from different sites can help distinguish true infection from contamination
- Consistent growth across samples suggests true infection rather than contamination
Minimizing Contamination
To minimize contamination, proper skin antisepsis with chlorhexidine or alcohol-based solutions should be performed, allowing adequate contact time (30-60 seconds), and using sterile technique during collection 3.
- Proper skin antisepsis is essential
- Sterile technique should be used during collection
- Adequate contact time for antisepsis is crucial
Treatment Algorithm
A targeted treatment algorithm can be developed based on the identification of gram-positive cocci in chains in positive blood cultures, using assays such as the Verigene Gram-positive blood culture assay 1.
- A treatment algorithm can be developed based on laboratory results
- The Verigene Gram-positive blood culture assay can aid in identification
- Targeted treatment can be initiated based on the algorithm