Contaminants in blood cultures: importance, implications, interpretation and prevention

Background: Despite the development of new microbiologic technologies, blood cultures (BCs) remain the first-line tool for the diagnosis of bloodstream infections. Their diagnostic value may be affected when a microorganism of questionable evidence is isolated-for example, coagulase-negative staphylococci, Bacillus spp., viridans group streptococci, Corynebacterium spp., Propionibacterium spp. and Micrococcus spp. Finally, making a correct diagnosis of pathogenicity (vs. contamination) is challenging. Aims: To review the current ways of dealing with the problem of BC contaminants (BCCs) and to provide practical suggestions to decrease BCC rates. Sources: PubMed electronic databases and existing reviews were searched up to December 2017 to retrieve relevant publications related to the topic. Contents: This review describes the burden of BCC and analyses the main current issues and controversies in interpreting the occurrence of potential BC contaminants. It focuses on the best-described approaches to decide whether BCC is present and discusses the different strategies of prevention in adults. (C) 2018 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.