groEL PCR had a higher discovery rate (17 PCR positives / 20 total positives = 85%) than 16S rRNA gene libraries (14 OTU matches / 20 total positives = 70%); however, 16S rRNA gene sequencing additionally identified one specimen co-infected with both Anaplasma and Ehrlichia. This co-infection was not revealed by amplification and sequencing of groEL. The relative abundance of each OTU in that co-infected specimen was 0.36% for Ehrlichia and 0.01% for Anaplasma, highlighting the ability of this approach to identify bacteria at very low abundances. This evidence concerns the gene HSPD1 and coinfection.