Prosthetic joint infection (PJI) is an increasingly important health concern in the Western world due to the rising number of
joint arthroplasties. Although most infections are considered to be monomicrobial, the introduction of sonication procedures
has led to an increase in the detection of polymicrobial infections. To date, no published studies have investigated the presence
of different clones of the same species in the infected patient. The objective of this study was to analyze whether the phenomenon
of polyclonality, or the appearance of different clones in the same sample, occurs in PJI. Bacteria isolated by sonication of the
retrieved implant from patients with theoretically monomicrobial PJI were included in the study. Two techniques (random amplified
polymorphic DNA [RAPD] and matrix-assisted laser desorption ionization–time of flight [MALDI-TOF] mass spectrometry)
were used to determine the presence of several clones in the same sample. Results were analyzed to determine bacterial species
and infection type (acute versus chronic). RAPD showed a predominance of polyclonal cases (16 of 19). However, when
performing the analysis with MALDI-TOF, all cases were shown to be polyclonal. We were unable to establish any relationship
between the two methodologies. Polyclonality is a common phenomenon in acute and chronic PJI. Further studies are needed to
establish the potential implications of this phenomenon on patient outcomesThis work was supported by a grant from the Spanish MINECO (no.
MAT2013-48224-C2-2-R). J.E. received travel grants from Pfizer, Leti, and bioMérieux and research
grants from Pfizer and Wyet
