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.

We present a novel electrical method for detecting viable bacteria in blood cultures that is 4 to 10 times faster than continuous monitoring blood culture systems (CMBCS) like the Bactec system. Proliferating bacteria are detected via an increase in the bulk capacitance of suspensions, and the threshold concentration for detection is ϳ10 4 CFU/ml (compared to ϳ10 8 CFU/ml for the Bactec system).Continuous monitoring blood culture systems (CMBCS), like the Bactec, BacT/Alert, and VersaTREK systems, currently serve as the "gold standard" for the detection of bacteremia and sepsis in the clinical setting. Blood cultures typically take between 12 and 72 h to yield positive results (3-5) and are usually continued for 120 h (5 days) before being deemed negative. For positive cultures, bacteria present are then identified (using various methods, ranging from traditional biochemical tests to PCR-based DNA analysis, that take an additional 3 to 24 h) before targeted antibiotics are administered. For every hour of delay in starting targeted antibiotic therapy, the risk of death for a given patient with sepsis increases by 6 to 10% (6). Since the blood culture step is by far the longer of the two diagnostic steps needed, cutting down the times to positivity (TTPs) of blood cultures is likely to reduce mortality and improve patient outcomes.At the time the patient begins to show clinical symptoms of sepsis, the concentration of bacteria present in blood is very low (1 to 100 CFU/ml in adults [13] and Ͻ10 CFU/ml in neonates [9]). Currently available CMBCS (like the Bactec, BacT/Alert, and VersaTREK systems) require the user to introduce the drawn blood (ϳ10 ml for adults and ϳ1 ml for neonates) into a bottle containing 20 to 40 ml of sterile bacterial growth medium and place it in a special incubation chamber. Here, the CMBCS monitor the levels of CO 2 in the suspension. A significant increase in CO 2 is taken to indicate the presence of viable bacteria in the suspension and hence in blood. Due to inherent limitations imposed by the metabolic rate of individual bacterial cells (e.g., one Escherichia coli bacterium consumes only ϳ2 ϫ 10

We present a novel method for detecting viable bacteria in suspensions such as milk and apple juice. Underlying the technique is the fact that bacteria in aqueous suspensions can store a large amount of charge, and thus act like (non-ideal) capacitors. Thus increased numbers of bacteria due to proliferation increases the capacitance of the bulk of the suspension. However, this increase cannot be directly measured since the capacitance of the solid-liquid interface (''double layer'') in effect ''screens'' the latter. We present a method (derived from an earlier one) that is able to discern such changes with high sensitivity and robustness. We also demonstrate its ability to monitor food quality/safety by detecting bacterial proliferation in ''real world'' liquid food samples like milk and apple juice. We are able to detect * 1, 10, 100, and 1000 CFU/mL of E. coli in milk in about 4.5, 3, 2, and 0.5 h, respectively. For the same initial loads, the corresponding times to detection (TTDs) for Lactobacillus in apple juice are approximately 8, 6, 4, and 1 h. These represent a greater than 4-fold reduction in TTD when compared to automated systems on the market such as RABIT, Bactometer etc. We can achieve such low TTDs for low initial loads since, due to the much greater effective charge holding capacity of bacterial cells (compared to surrounding media), we are able to detect a change in the overall bulk capacitance of the suspension as the bacterial numbers cross a threshold of around 500 CFU/mL.

BackgroundBiofilms occur on a wide variety of surfaces including metals, ceramics, glass etc. and often leads to accumulation of large number of various microorganisms on the surfaces. This biofilm growth is highly undesirable in most cases as biofilms can cause degradation of the instruments and its performance along with contamination of the samples being processed in those systems. The current “offline” biofilm removal methods are effective but labor intensive and generates waste streams that are toxic to be directly disposed. We present here a novel process that uses nano-energetic materials to eliminate biofilms in < 1 second. The process involves spray-coating a thin layer of nano-energetic material on top of the biofilm, allowing it to dry, and igniting the dried coating to incinerate the biofilm.ResultsThe nanoenergetic material is a mixture of aluminum (Al) nanoparticles dispersed in a THV-220A (fluoropolymer oxidizer) matrix. Upon ignition, the Al nanoparticles react with THV-220A exothermically, producing high temperatures (>2500 K) for an extremely brief period (~100 ms) that destroys the biofilm underneath. However, since the total amount of heat produced is low (~0.1 kJ/cm2), the underlying surface remains undamaged. Surfaces with biofilms of Pseudomonas aeruginosa initially harboring ~ 107 CFU of bacteria /cm2 displayed final counts of less than 5 CFU/cm2 after being subjected to our process. The byproducts of the process consist only of washable carbonaceous residue and gases, making this process potentially inexpensive due to low toxic-waste disposal costs.ConclusionsThis novel method of biofilm removal is currently in the early stage of development. However, it has potential to be used in offline biofilm elimination as a rapid, easy and environmentally friendly method.

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