Abstract
Aim
The frequency of arthroplasty among older people is increasing. Taking care of Prosthetic Joint infection (PJI) in this specific population is a challenge. The purpose of this multicentric retrospective study was to evaluate the bacterial epidemiology of hip and knee PJI in octogenarians and nonagenarians over ten years.
Method
Data were collected using two softwares* in each of the 4 Centers participating.
Inclusion criteria:
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age ≥ 80 years PJI (knee or hip)
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between January 2007 and December 2016
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microbiological data available (strains isolated from osteo-articular samples)
Bacterial identification: biochemical methods, followed by Malditof since 2009. For Staphylococcus aureus, Pseudomonas aeruginosa and Enterobacteriaceae, resistance profiles to antibiotics frequently used in PJI were collected. Antimicrobial susceptibility testing: disk diffusion (recommendations: French Society of Microbiology yearly updated).
Results
413 patients were included: median age was 85 years and sex ratio was 0.6. 137 were knee PJI and 276 hip. 34% of the infections occurred < 1 month after implantation, and 49% > 6 months after implantation. Among all bacterial isolates (N=817), there was 55% of Gram positive cocci and 36% of Gram negative rods. 112 (27%) were polymicrobial infections. There was a majority of gram negative rods (41%) among isolates from polymicrobial infections. Concerning drug resistance, there was a stable proportion of ESBL among Enterobacteria (16%), whereas Methicillin resistance among S. aureus decreased from 43% in 2007 to 12% in 2016.
Conclusions
An important proportion of PJI in older patients are polymicrobials, and a lot of them involve gram negative rods, almost as frequently as S. aureus. These infections are difficult to treat, and resistance of gram negative strains is one of the obstacles to overcome among these patients where surgery is not always possible.
* Sirweb (I2A) and Glims (MIPS)
