Amplified-fragment length polymorphism analysis of Propionibacterium isolates implicated in contamination of blood products

Propionibacterium acnes is implicated in most cases of bacterial contamination of platelet concentrates (PCs). To determine the source of contamination, amplified-fragment length polymorphism (AFLP) analysis was applied. This DNA fingerprinting technique was used to study the molecular relationship of 44 isolates derived from 22 PCs and 22 corresponding red blood cells concentrates (RBCs) from the same whole blood donations. The AFLP results together with sequencing analysis of the 1200 bp of the 16S ribosomal RNA gene revealed the existence of three main groups: two groups (groups 2 and 3) (55%) consisted of isolates that did not originate from skin flora and another group (group 1) (45%) comprised bacteria belonging to the skin flora. This latter group showed complete homology with reference strains of P. acnes. Therefore these isolates can be considered as P. acnes strains. In contrast, contaminants from groups 2 and 3 were shown to be molecularly unrelated to the P. acnes found on the skin surface. The AFLP is reproducible and gave invaluable information about the nature of Propionibacteria contaminating PCs. To gain more insights into the source of contamination, this technique could be exploited in further studies to determine the molecular relationship of different bacteria commonly found in blood products.