Heterogeneity of Staphylococcus epidermidis in prosthetic joint infections : time to reevaluate microbiological criteria?

Prosthetic joint infection (PJI) is a feared and challenging to diagnose complication after arthroplasty, with Staphylococcus epidermidis as the major pathogen. One important criteria to define PJI is the detection of phenotypically indistinguishable microorganisms with identical antibiotic suscepti...

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Bibliographic Details
Published in:European Journal of Clinical Microbiology & Infectious Diseases
Main Authors: Widerström, Micael, Stegger, Marc, Johansson, Anders, Gurram, Bharat Kumar, Larsen, Anders Rhod, Wallinder, Lars, Edebro, Helen, Monsen, Tor
Format: Article in Journal/Newspaper
Language:English
Published: Umeå universitet, Institutionen för klinisk mikrobiologi 2022
Subjects:
Staphylococcus epidermidis
Genomics
Multidrug resistant
Prosthetic joint infection
Within-patient variation
Diagnosis
Polymicrobial
Infectious Medicine
Infektionsmedicin
Northern Sweden
Online Access:http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-188180
https://doi.org/10.1007/s10096-021-04352-w
Description
Summary:Prosthetic joint infection (PJI) is a feared and challenging to diagnose complication after arthroplasty, with Staphylococcus epidermidis as the major pathogen. One important criteria to define PJI is the detection of phenotypically indistinguishable microorganisms with identical antibiotic susceptibility pattern in at least two different samples. However, owing to phenotypical variation within genetic clones and clonal variation within a phenotype, the criteria may be ambiguous. We investigated the extent of diversity among coagulase-negative staphylococci (CoNS) in PJI and characterised S. epidermidis isolates from PJI samples, specifically multiple S. epidermidis isolates identified in individual PJI patients. We performed a retrospective cohort study on 62 consecutive patients with PJI caused by CoNS from two hospitals in Northern Sweden. In 16/62 (26%) PJIs, multiple S. epidermidis isolates were available for whole-genome analyses. Hospital-adapted multidrug-resistant genetic clones of S. epidermidis were identified in samples from 40/62 (65%) of the patients using a combination of pulsed-field gel electrophoresis and multilocus sequence typing. Whole-genome sequencing showed the presence of multiple sequence types (STs) in 7/16 (44%) PJIs where multiple S. epidermidis isolates were available. Within-patient phenotypical variation in the antibiotic susceptibility and/or whole-genome antibiotic resistance gene content was frequent (11/16, 69%) among isolates with the same ST. The results highlight the ambiguity of S. epidermidis phenotypic characterisation as a diagnostic method in PJI and call for larger systematic studies for determining the frequency of CoNS diversity in PJIs, the implications of such diversity for microbiological diagnostics, and the therapeutic outcomes in patients.

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