An Istar intensified CCD camera from Andor has been used by scientists to validate the potential for a new generation of rapid, automated biosensor detection systems for hospital-acquired infections.
At a time of rising levels of MRSA and other hospital-acquired infections, laser-induced breakdown spectroscopy (LIBS) has been demonstrated to be a rapid and reliable technique for detection of life-threatening bacterial pathogen species that can be found in such medical environments.
Scientists have used chemometrics analysis of LIBS data in a blind test to successfully identify five pathogenic bacterial samples and differentiate between strains of a multiple-antibiotic-resistant species.
Dr Rosalie Multari and her colleagues at Applied Research Associates believe that the ability to distinguish both species and strains using only raw spectra raises the prospect of rapid diagnostic instrumentation for use both within laboratories and in the field.
Multari's team used the Andor Istar intensified CCD camera to analyse 10 accumulated spectra from the laser-induced plasma plumes, with each spectrum accurately delayed by one microsecond from the laser pulse and integrated on a 20-microsecond temporal scale.
The overall one-second detection period allowed the identification of the five bacterial samples with 100 per cent accuracy, including Escherichia coli, three methicillin-resistant Staphylococus aureas (MRSA) strains and an unrelated MRSA strain.
Andrew Dennis, director of product management at Andor, said the Istar is suitable for challenging LIBS measurements.
The cameras feature a fully integrated, software-controlled digital delay and ultrafast electronics for sub-2ns optical shuttering capabilities, a large range of photocathodes, including UV-enhanced and broadband options, with high on/off ratio in excess of 100,000,000 even in the UV region.
Dennis added that coupled with Echelle-based spectrographs, the Istar allows access to high bandwidth coverage while simultaneously achieving high spectral resolution and high time-resolution.
Multari's work follows a 2006 investigation of bacterial entities discrimination using LIBS spectra.
Matthieu Baudelet and colleagues used the Andor Istar and Mechelle, an Echelle-based spectrograph, to investigate the relative concentration of six trace elements in pure samples of five bacterial species, and showed the equipment's suitability for accurate identification and discrimination.
Unlike other atomic spectroscopy techniques, LIBS does not require intensive sample preparation and lends itself to automated or unattended situations outside of the controlled laboratory environment.
The LIBS technique directs a focused laser pulse onto a target, which may be a solid, liquid, or a gas.
The energy from the pulse vaporises, atomises and ionises the target material to form a micro-plasma, which emits light as a result of relaxation of electrons from excited to lower-energy states.
Typically, this light is routed to an Echelle spectrograph and the spectral signature of the plasma is uniquely characteristic of the elements within the target.
