Polymorphisms of agr locus correspond to distinct genetic patterns of virulence in Staphylococcus aureus clinical isolates from orthopedic implant infections
Research Unit on Implant Infections, Rizzoli Orthopaedic Institute, Bologna, Italy.Journal of Biomedical Materials Research Part A (Impact Factor: 3.37). 09/2010; 94(3):825-32. DOI: 10.1002/jbm.a.32764
Staphylococcus aureus is the leading etiologic agent of orthopedic implant infections. It is endowed with the accessory gene regulator (agr) locus that modulates expression of many virulence genes. Four allelic groups of agr have been recognized within this bacterial species. Here, 200 S. aureus isolates from orthopedic implant infections, typed at the start depending on their agr group, were screened for the presence of adhesin and leukotoxin genes. Interestingly, specific virulence gene patterns emerged in association with agr groups. The most frequently observed agr groups, agr I and agr II, were associated with the presence of sdrE, fib (agr II more than agr I), fnbB (agr I more than agr II), and lukE/lukD (agr II more than agr I). The third more frequent agr group, agr III, differed clearly from agr I and II, exhibiting high prevalence of bbp, generally not harbored by agr I and II, and copresence of bbp with cna, whereas high prevalence of the tandem sdrE/fib marked definitely agr II (91% of agr II isolates), and, though less strictly, agr I, in which prevailed the peculiar fib/fnbB pattern. The only four isolates belonging to agr IV showed full copresence of bbp with fib. Results point out distinct patterns of virulence genes, which underlie distinct evolutive strategies associated to agr groups in S. aureus causing orthopedic implant infections.
- European cells & materials 07/2011; 21. · 4.89 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Infection is still the major complication of orthopedic implants and projections based on the actual trend indicate that total hip and knee arthroplasties and their consequent infection burden are destined to greatly increase. Staphylococcus aureus and Staphylococcus epidermidis are the leading etiologic agents of orthopedic implant infection. Here we report on epidemiology of implant-related Staphylococcus infections in orthopedics, also referring to our experience, and focus on the crucial role of bacterial adhesins and on their ability to direct the pathogenesis process. Bacteria initiate implant infection by adhering to biomaterials. In the early steps of infection, adhesins mediate the specific interaction between microbial cells and the extracellular matrix proteins filming biomaterial surface. Then adhesin-mediated anchorage allows bacteria to cling to the biomaterial surface and to produce a biofilm that favors their ability to resist antibiotics. With the aim to prevent implant-related infections, anti-infective and infection-resistant biomaterials are being developed. The research for novel therapeutic strategies is incited by the emergence of antibiotic-resistant bacteria. Vaccines against the adhesins or antisense molecules against virulence genes can open a future in combating implant infections.Future Microbiology 11/2011; 6(11):1329-49. DOI:10.2217/fmb.11.117 · 4.28 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: This study aimed at preparation and in vitro and in vivo evaluation of novel bioactive, biodegradable, and antibacterial nanocomposite coating for the improvement of stem cells attachment and antibacterial activity as a candidate for dental implant applications. Poly (lactide-co-glycolide)/bioactive glass/hydroxyapatite (PBGHA) nanocomposite coating was prepared via solvent casting process. The nanoparticle amounts of 10, 15, and 20 weight percent (wt%) were chosen in order to determine the optimum amount of nanoparticles suitable for preparing an uniform coating. Bioactivity and degradation of the coating with an optimum amount of nanoparticles were evaluated by immersing the prepared samples in simulated body fluid and phosphate buffer saline (PBS), respectively. The effect of nanocomposite coating on the attachment and viability of human adipose-derived stem cells (hASCs) was investigated. Kirschner wires (K-wires) of stainless steel were coated with the PBGHA nanocomposite coating, and mechanical stability of the coating was studied during intramedullary implantation into rabbit tibiae. The results showed that using 10 wt% nanoparticles (5 wt% HA and 5 wt% BG) in the nanocomposite could provide the desired uniform coating. The study of in vitro bioactivity showed rapid formation of bone-like apatite on the PBGHA coating. It was degraded considerably after about 60 days of immersion in PBS. The hASCs showed excellent attachment and viability on the coating. PBGHA coating remained stable on the K-wires with a minimum of 96% of the original coating mass. It was concluded that PBGHA nanocomposite coating provides an ideal surface for the stem cells attachment and viability. In addition, it could induce antibacterial activity, simultaneously.Journal of Materials Science Materials in Medicine 11/2011; 23(2):485-95. DOI:10.1007/s10856-011-4507-0 · 2.59 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.