In 9 cases (5 PJIs and 4 AFs), MALDI-TOF MS detected 2 different organisms belonging
to the same genus; 8 of these involved 2 different CoNS. Single specimens yielding
Staphylococcus hominis were found in 2 PJI subjects with S. epidermidis as the pathogen.
One PJI subject had S. aureus isolated from multiple specimens with a single specimen
also yielding S. epidermidis. There were no cases of PJI in which 2 pathogens belonging
to the same genus were found. Two subjects with indeterminate culture results had 2
Staphylococcus species isolated, 1 with S. epidermidis and Staphylococcus lugdunensis and
another with S. aureus and Staphylococcus caprae. Two subjects with AF had Staphylococcus
capitis isolated in addition to S. hominis, and 1 subject had S. capitis and S. epidermidis isolated.
The final AF subject had S. hominis and Staphylococcus pasteuri isolated. In all subjects
with AF, the different CoNS were isolated from the same tissue specimens. In
addition, 16S rRNA gene PCR/sequencing was used to identify 2 different species of
Prevotella (Prevotella buccalis and Prevotella timonensis) in a subject with PJI.