Acyl homoserine lactone (acyl-HSL)-mediated gene regulation has been shown to influence biofilm formation in one Burkholderia cepacia cystic fibrosis isolate, but it is not known whether this relationship is a consistent feature of the several genomic species that make up the B. cepacia complex (BCC). We screened strains belonging to genomovars I to V of the BCC for biofilm formation on an abiotic surface and for acyl-HSL synthesis. We determined that organisms from each of these genomovars were capable of biofilm formation. Similarly, acyl-HSL was synthesized by organisms from each of genomovars I to V, with most isolates producing octanoyl-HSL in greatest abundance. When biofilms were grown in Luria broth, acyl-HSL synthesis and biofilm formation appeared to be associated, but these phenotypes were independent when the biofilms were grown in basal salts containing citrate. Genomovar V strains synthesized the greatest quantities of acyl-HSL, and genomovar II and III-A strains elaborated the most abundant biofilms. Quorum sensing may play a role in BCC pathogenesis, but it may not regulate biofilm formation under all growth conditions. Burkholderia cepacia has been recognized as a problematic opportunistic pathogen, particularly among cystic fibrosis (CF) and chronic granulomatous disease patients. Accurate identification of this organism can be problematic as its taxonomy continues to evolve. The B. cepacia complex (BCC) is a group of phenotypically related but genotypically distinct organisms. The BCC is divided into at least nine closely related genomic species or genomovars. Genomovars II, IV, V, VII, VIII, and IX have been named Burkholderia multivorans, Burkholderia stabilis, Burkholderia vietnamiensis, Burkholderia ambifaria, Burkholderia anthina, and Burkholderia pyrrocinia, respectively. Genomovars I, III, and VI have not been formally named, pending the availability of differential diagnostic tests, but genomovar I is understood to be B. cepacia.Interest in acyl homoserine lactone (acyl-HSL)-mediated quorum sensing and bacterial biofilm formation has increased in recent years. Quorum sensing regulates the expression of virulence factors in several organisms, including the CF pathogen, Pseudomonas aeruginosa (29,30,34). Biofilm formation by P. aeruginosa has been recognized as an important clinical problem due to the intrinsically high level of antibiotic resistance of bacteria growing in the biofilm (2, 3, 26). Maturation of a P. aeruginosa biofilm requires synthesis of the quorum sensing signal, 3-oxo-dodecanoyl HSL (3OC 12 -HSL), indicating that quorum sensing is necessary for biofilm formation (7). Quorum sensing and biofilm formation have also been observed with B. cepacia (10,13,17,24). BCC organisms are problematic since some can be highly virulent and highly transmissible in CF patients (11,14,18). In addition, treatment is often complicated by the high degree of antibiotic resistance exhibited by these organisms, and this resistance may be enhanced in biofilms. The purpose of these studies was ...

Ultrasound-guided intervention is becoming an increasingly popular and valuable tool in the critical care setting. In general, image-guided procedures can expedite wait times and increase the accuracy, safety, and efficacy of many procedures commonly performed within intensive care units. In the intensive care unit setting, ultrasound has particular advantages over other imaging modalities such as computed tomography and fluoroscopy, including real-time visualization, portability permitting bedside procedures, and reduced exposure to nephrotoxic contrast agents. We review the technical and procedural aspects of a number of ultrasound-guided interventions appropriate for critical care patients. These include central venous catheter deployment, thoracentesis, paracentesis, and drainage of a wide variety of abscesses, and percutaneous nephrostomy, percutaneous cholecystectomy, and inferior vena cava filter placement. Although we believe ultrasound is significantly underutilized in critical care today, we anticipate that with the improvement of ultrasound technology and the innovation of new ultrasound-guided procedures, the role of ultrasound in the intensive care unit will continue to expand, with bedside ultrasound-guided interventions increasingly becoming the norm.

The frequency and variety of spinal instrumentation has increased tremendously over the past 100 years, and imaging plays an important role in evaluating the postoperative spine. Although assessment of spinal hardware often involves a multimodality approach, plain radiographs are the most commonly used modality, given accessibility, cost, relatively low radiation dose compared with computed tomography, and provision of positional information. An approach to assessment of plain radiographs of the postoperative spine is discussed, and examples of common postoperative complications are provided, including infection, hardware failure, incomplete fusion, and junctional failure.