A case of an atypical femoral fracture associated with bacterial biofilm--pathogen or bystander?

We report a case of an 86-year-old woman with an atypical femoral fracture (AFF) who was treated with intramedullary nailing followed by lateral femoral plating. She developed a second femoral shaft fracture distal to the intramedullary nail which required a second operation. Biopsy of the periosteum overlying the site of the initial proximal AFF was sent for pathogen analysis. Using the Ibis T5000 platform and the BAC plate assay, a polymicrobial infection was diagnosed consisting of Bifidobacterium subtile and Pseudomonas mendocina. This raises the possibility that bacterial infections may play some role in atypical fractures of the femur.

Phenotypic differentiation and seeding dispersal in non-mucoid and mucoid Pseudomonas aeruginosa biofilms.

There is growing evidence that Pseudomonas aeruginosa biofilms exhibit a multicellular developmental life cycle analogous to that of the myxobacteria. In non-mucoid PAO1 biofilms cultured in glass flow cells the phenotypic differentiation of microcolonies into a motile phenotype in the interior of the microcolony and a non-motile surrounding 'wall phenotype' are described. After differentiation the interior cells coordinately evacuated the microcolony from local break out points and spread over the wall of the flow cell, suggesting that the specialized microcolonies were analogous to crude fruiting bodies. A microcolony diameter of approximately 80 microm was required for differentiation, suggesting that regulation was related to cell density and mass transfer conditions. This phenomenon was termed 'seeding dispersal' to differentiate it from 'erosion' which is the passive removal of single cells by fluid shear. Using the flow cell culturing method, in which reproducible seeding phenotype in PAO1 wild-type was demonstrated, the effects of quorum sensing (QS) and rhamnolipid production (factors previously identified as important in determining biofilm structure) on seeding dispersal using knockout mutants isogenic with PAO1 was investigated. Rhamnolipid (rhlA) was not required for seeding dispersal but las/rhl QS (PAO1-JP2) was, in our system. To assess the clinical relevance of these data, mucoid P. aeruginosa cystic fibrosis isolate FRD1 was also investigated and was seeding-dispersal-negative.

Ultrastructural analysis of indwelling vascular catheters: a quantitative relationship between luminal colonization and duration of placement.

To assess the degree of luminal and extraluminal colonization of long-term central venous catheters (CVC), 359 indwelling silicone CVC from 340 consecutive cancer patients were examined. All CVC were cultured by the roll-plate and sonication quantitative culture techniques. Semiquantitative electron microscopy was done on 39 CVC associated with catheter infections and on 26 culture-negative controls. An additional 10 culture-negative CVC obtained after death were also studied by electron microscopy. Ultrastructural colonization and biofilm formation was universal and quantitatively independent of clinical catheter-related infections. Ultrastructural colonization and biofilm formation was predominantly luminal in long-term CVC (> 30 days). Based on a composite definition, the sensitivity of the roll-plate catheter tip culture was 42%-45% compared with 65%-72% for the sonication of the tip. Colonization of indwelling catheters is universal regardless of culture results. For long-term CVC, colonization becomes predominantly luminal and extraluminal quantitative catheter cultures are of limited diagnostic sensitivity.

Nondysenteric intestinal amebiasis. Colonic morphology and search for Entamoeba histolytica adherence and invasion.

There is controversy regarding the presence of colonic mucosal abnormalities or mucosal invasion by Entamoeba histolytica in patients with "nondysenteric intestinal amebiasis." To determine the role of E. histolytica in causing symptoms and mucosal changes and to detect if mucosal invasion by E. histolytica is present in nondynsenteric intestinal amebiasis, we evaluated 24 E. histolytica-infected patients (stool microscopy positive for E. histolytica) and 12 noninfected controls who presented with chronic gastrointestinal symptoms, but without dysentery, to a clinic in Calcutta. The colonic mucosa was evaluated at colonoscopy, and mucosal biopsies obtained from the cecum, sigmoid colon, and rectum were evaluated by light microscopy, indirect immunofluorescence microscopy, and scanning electron microscopy. At colonoscopy mucosal ulcerations were absent in all the controls and all except one of the E. histolytica-infected patients. E. histolytica trophozoites or cysts were not seen in the lamina propria or on the luminal surface in any infected patient by light and immunofluorescence microscopy. On scanning electron microscopy, structures that resembled rounded E. histolytica trophozoites were seen on the luminal surface in two of 19 cecal specimens from the infected patients. Moderate or severe mucosal inflammation was frequent on light microscopy in both the E. histolytica-infected patients and the noninfected controls with the cecum involved in two thirds of both groups. Antibodies to E. histolytica were detected in serum of 25% of study patients and 58% of controls. Mucosal inflammation did not correlate with stool positivity for E. histolytica or seropositivity for ameba antibody.(ABSTRACT TRUNCATED AT 250 WORDS)