[Show abstract][Hide abstract] ABSTRACT: Helcococcus kunzii was isolated by sonication and conventional cultures obtained from a case of infection following total knee prosthesis in
an immunocompetent patient. The patient recovered uneventfully. This is the first known case of an H. kunzii prosthetic joint infection.
[Show abstract][Hide abstract] ABSTRACT: The aim of our study was the evaluation of an in vivo experimental model of implant-related septic arthritis. 5 × 10 mm strips out of a polyethylene sheet 500 microns thick were incubated with a 0.5 McFarland bacterial suspension of collection strains S. aureus and S. epidermidis. A surgical experimental model was prepared, implanting the samples in the subquadricipital articular space of the rabbit's knee. After 7 days of survival, the knee joint was opened wide through the previous surgical approach and the polyethylene sample was retrieved. The UHMWPE samples were processed following a sonication and quantification protocol. Ten rabbits for each species were studied, five with each material. Negative controls (UHMWPE strips without attached bacteria) were also implanted in contralateral knees. S. aureus colonies were detected only in three rabbits with non-treated UHMWPE and in two with vitamin E-doped UHMWPE. No differences in colony counts were observed for S. aureus. No growth was detected for S. epidermidis, although clinical signs of infection were detected in all animals with inoculated samples. The model was useful to evaluate the effect of modifications in biomaterials, although highly pathogenic bacteria are needed to obtain quantifiable data.
Journal of Physics Conference Series 12/2010; 252(1):012016. DOI:10.1088/1742-6596/252/1/012016
[Show abstract][Hide abstract] ABSTRACT: Biomaterials may improve its capacity to resist bacterial adherence, and subsequent infection through material changes. Our aim was to test the bacterial adherence to vitamin E (VE) doped UHMWPE with S. aureus and S. epidermidis (collection and clinical strains), compared to virgin material. Experimental UHMWPE with 3%, 0.4%, and commercial 0.1% VE concentration (1000 ppm) were tested. The biofilm-developing ability was used as a covariable. The collection strain of S. aureus showed significantly less adherence to the commercial VE UHMWPE (p=0.036) but the clinical strains did not significantly modified its adhesion to UHMWPE in presence of VE. The collection strain of S. epidermidis showed significantly less adherence to experimental UHMWPE with VE, independently of the concentration used (p=0.008). However, only 1 of the 4 clinical strains under study clearly confirmed these results in commercial VE polyethylene. Vitamin E doped UHMWPE affects the adherence of some S. aureus and S. epidermidis strains, independently of the concentration in use, but the results showed important intraspecies differences.
Journal of Physics Conference Series 11/2010; 252(1). DOI:10.1088/1742-6596/252/1/012014
[Show abstract][Hide abstract] ABSTRACT: To improve the microbiological diagnosis of device-related osteoarticular infections, we have developed a protocol based on
the sonication of device samples, followed by concentration and inoculation of the sonicate in a broad variety of media in
a quantitative manner. Sixty-six samples from 31 patients were included in the study (17 of them with clinical diagnosis of
infection). The sonication procedure had a sensitivity of 94.1%, which is better than that of conventional cultures (88.2%).
One case of contamination and six cases of unexpected positive cultures were detected (specificity of 42.8%): two of these
were considered to represent true infection, while the other four were considered to be nonsignificant (corrected specificity
of 50%), although the clinical importance of these isolates is questionable. When we analyzed the number of CFU, no breakpoint
between significant and nonsignificant isolates could be established. Based on our results, the procedure of sonication of
retrieved implants is better than conventional cultures for the diagnosis of device-related infections. The significance of
some isolates in patients without clinical infection remains uncertain. However, they may become pathogens and cannot be routinely
considered to be contamination.