ABSTRACT
To analyze national prevalence, genomovar distribution, and epidemiology of the Burkholderia cepacia complex in Italy, 225 putative B. cepacia complex isolates were obtained from 225 cystic fibrosis (CF) patients attending 18 CF centers. The genomovar status of these isolates was determined by a polyphasic approach, which included whole-cell protein electrophoresis and recA restriction fragment length polymorphism (RFLP) analysis. Two approaches were used to genotype B. cepacia complex isolates: BOX-PCR fingerprinting and pulsed-field gel electrophoresis (PFGE) of genomic macrorestriction fragments. A total of 208 (92%) of 225 isolates belonged to the B. cepacia complex, with Burkholderia cenocepacia as the most prevalent species (61.1%). Clones delineated by PFGE were predominantly linked to a single center; in contrast, BOX-PCR clones were composed of isolates collected either from the same center or from different CF centers and comprised multiple PFGE clusters. Three BOX-PCR clones appeared of special interest. One clone was composed of 17 B. cenocepacia isolates belonging to recA RFLP type H. These isolates were collected from six centers and represented three PFGE clusters. The presence of insertion sequence IS 1363 in all isolates and the comparison with PHDC reference isolates identified this clone as PHDC, an epidemic clone prominent in North American CF patients. The second clone included 22 isolates from eight centers and belonged to recA RFLP type AT. The genomovar status of strains with the latter RFLP type is not known. Most of these isolates belonged to four different PFGE clusters. Finally, a third clone comprised nine B. pyrrocinia isolates belonging to recA RFLP type Se 13. They represented three PFGE clusters and were collected in three CF centers.
Subject(s)
Burkholderia Infections/transmission , Burkholderia cepacia complex/isolation & purification , Cystic Fibrosis/epidemiology , Cystic Fibrosis/microbiology , Disease Outbreaks , Bacterial Typing Techniques , Burkholderia Infections/epidemiology , Burkholderia Infections/microbiology , Burkholderia cepacia complex/classification , Burkholderia cepacia complex/genetics , Clone Cells , Electrophoresis, Gel, Pulsed-Field , Genotype , Humans , Italy/epidemiology , Polymerase Chain Reaction/methods , Prevalence , Sputum/microbiologyABSTRACT
Fracture and mechanical characterization of bone composite composed of polymethylmethacrylate and hydroxyapatite (HA) at different contents was carried out. Hydroxyapatite is added in order to improve cement biocompatibility, but it is expected that it also affects mechanical properties. Specimens were either stored in air at 37 degrees C for 120 h or in physiological solution (PhS-37), in order to establish the influence of storage conditions upon mechanical behavior. One set of specimens was also postcured at 120 degrees C for 4 h to take into account the influence of free monomer. Fracture experiments revealed some non-linearity in load-displacement records and differences in trends between initiation and propagation values of the fracture surface energies. The trends in the data shows that HA acts as a rigid filler enhancing fracture resistance, flexural modules and yield stress, up to a certain content. Beyond the latter limit, properties suffer a deterioration because the addition of HA also affects the cement porosity. Absorbed water acts as plasticizer leading to a decrease in mechanical properties. The highest propagation strain energies were exhibited by materials aged in PhS-37.
