We report a novel buffer electric and dielectric relaxation time tuning technique, coupled with a glutaraldehyde (Glt.) cross-linking cell fixation reaction that allows for sensitive dielectrophoretic analysis and discrimination of bovine red blood cells of different starvation age. Guided by a single-shell oblate spheroid model, a zwitterion buffer composition is selected to ensure that two measurable crossover frequencies (cof's) near 500 kHz exist for dielectrophoresis (DEP) within a small range of each other. It is shown that the low cof is sensitive to changes in the cell membrane dielectric constant, in which cross-linking by Glt. reduces the dielectric constant of the cell membrane from 10.5 to 3.8, while the high cof is sensitive to cell cytoplasm conductivity changes. We speculate that this enhanced particle polarizability that results from the cross-linking reaction is because younger (reduced starvation time) cells possess more amino groups that the reaction can release to enhance the cell interior ionic strength. Such sensitive discrimination of cells with different age (surface protein density) by DEP is not possible without the zwitterion buffer and cleavage by Glt. treatment. It is then expected that rapid identification and sorting of healthy from diseased cells can be similarly sensitized.

The use of "engineering controls" included the integration of NFCs into the IV access system both for needle safety and for the prevention of central-line associated bloodstream infections (CLABSI) (3-5). NFCs allow for the administration of IV fluids, medications and blood to indwelling venous or arterial catheters without the use of needles. NFCs are also used for the withdrawal of blood samples and for aspiration of blood to check the catheter for patency. While the introduction of NFCs greatly reduced the risk of needle-stick injuries for healthcare workers, their use has been associated with other complications such as an increase in catheter occlusions and CLABSIs (6-11). In response to the increase in CLABSI related to the use of NFCs, medical device companies began designing and developing lower-risk devices (12). Over the past 20 years, 4 categories of NFC designs have emerged (2, 13). While there is no regulatory body that recognizes the categories of NFC as being indicative of function or performance (13), NFCs are typically marketed as being "positive", "negative", "neutral" (6, 12-16) or pressure-activated anti-reflux (9, 13, 17). The characteristics of each category of NFC indicate the mechanism and action of the NFC upon connection/disconnection.

Bacterial colonization and biofilm formation on an orthopedic implant surface is one of the worst possible outcomes of orthopedic intervention in terms of both patient prognosis and healthcare costs. Making the problem even more vexing is the fact that infections are often caused by events beyond the control of the operating surgeon and may manifest weeks to months after the initial surgery. Herein, we review the costs and consequences of implant infection as well as the methods of prevention and management. In particular, we focus on coatings and other forms of implant surface modification in a manner that imparts some antimicrobial benefit to the implant device. Such coatings can be classified generally based on their mode of action: surface adhesion prevention, bactericidal, antimicrobial-eluting, osseointegration promotion, and combinations of the above. Despite several advances in the efficacy of these antimicrobial methods, a remaining major challenge is ensuring retention of the antimicrobial activity over a period of months to years postoperation, an issue that has so far been inadequately addressed. Finally, we provide an overview of additional figures of merit that will determine whether a given antimicrobial surface modification warrants adoption for clinical use.

Tools and instruments available in the clinical microbiology labs for analysis of patient samples and diagnosis are constantly evolving. The main impetus behind this is to decrease the overall time taken to obtain the results from the instruments, enhance the ease of sample processing, increasing the sample turn-around time with the ultimate goal of earlier patient treatment and better recovery rates. This is especially true in the case of antibiotic susceptibility testing (AST), where every hour saved in obtaining the results leading to an earlier switch to targeted antibiotic therapy will have a direct influence on improving clinical outcomes. Reduction in the time to obtain AST results reduces the duration of use of broad-spectrum antibiotics, which in turn decreases the emergence of antibiotic resistance among bacteria. Many of the traditional methods available for AST are labor intensive and slow despite being precise in obtaining results. Thus, there is a trend towards development and use of automated diagnostic devices which are rapid and easy to use. This review article provides a detailed summary of traditional AST methods, currently used automated methods, and focuses on some of the promising emerging and future technologies in the field of rapid antibiotic susceptibility profiling.

The technique described enables the user to detect the presence and proliferation of bacteria through an increase in the bulk capacitance (C) of the suspension, which is proportional to the bacteria count, at practical frequencies less than 1 MHz. The geometry of the micro-capillary design employed increases the bulk resistance (R) of the medium, thus increasing its RC time. This makes the measured reactance sensitive to changes in the bulk capacitance, which is usually masked by the much larger surface capacitance. The sensitivity is further enhanced by the existence of a minimum in the value of the reactance at a frequency proportional to the inverse medium RC time. The value of this reactance minimum and the frequency at which the minimum is recorded are dependent on the bacteria count and permit the detection of an initial concentration of approximately 100 CFU ml(-1) of E. coli within 3 hours of incubation, in comparison with the previous reported values of about 8 hours, with an initial load of 1000 CFU ml(-1).