Optical waveguides – Optical waveguide sensor
Reexamination Certificate
2000-07-31
2004-04-06
Sanghavi, Hemang (Department: 2874)
Optical waveguides
Optical waveguide sensor
C435S034000
Reexamination Certificate
active
06718077
ABSTRACT:
The present invention refers to a method and device for the detection of microorganisms using a combination of microbiological procedures with devices constructed with fiber optics and related components.
The microbiological procedures enable the microorganisms to be selectively cultivated and these, when in physical contact with a conveniently constructed fiber optic circuit, permit the detection and monitoring of the microorganisms in a fast and accurate way.
BACKGROUND OF INVENTION
Microorganisms are life forms that despite their micrometrical size scale significantly affect human life. They may constitute viruses, bacteria, fungi, protozoa and algae. They are present in solids, liquids and air; and in all cases it may be of vital interest or importance to detect the specific presence and/or to monitor, qualitatively or quantitatively, the growth over time of one or more of these microorganisms. Many of them are of use to various types of industries, such as food industries, brewery, viticulture, pharmaceutical, etc., for the catalysis of many biochemical reactions of commercial interest, amongst others. Other microorganisms do not seem to serve any other practical purpose, but are, in principle, harmless to human health. However, some of these microorganisms may become dangerous, for a series of reasons, after undergoing certain types of biological transmutations and whereupon they are termed pathogenic. These pathogens may exist and develop in various environments. Other types of microorganisms may be intrinsically dangerous, meaning that they are naturally constituted as noxious to human health. Overall, the presence and the concentration of some of the referred microorganisms directly affect: (i) the quality (potability and suitability for bathing)of the water for consumption in major urban centers and seaside resorts, possibly causing a series of diseases, such as diarrhea; (ii) the quality of food, which may generically cause food poisoning, and, particularly, “hamburger disease” and (iii) the quality of air in clinics, outpatients and hospitals where the presence of aerobiological microorganisms constitutes, for example, an important vector for hospital infections. In any of these cases, it may be of great interest or vital importance to detect the presence of certain microorganisms in real time or almost immediately, and consequently to monitor their evolution over time aiming to infer some useful information. At present, the conventional techniques for surveying microorganisms are closely linked to laboratory and outpatient procedures and based in selective biological culture and in the use of microscopy for direct visual observation. These techniques are reasonably complex, as they demand from the operator significant intervention and skill in order to obtain dependable results, and typically require 1 to 10 days for completion. This means that the conventional techniques require an average of 72 h between the capture of the microorganism, its isolation, identification and consecutive monitoring of its evolution over time. The standard procedures concerning bacteriological tests are furnished by the American Public health Association (APHA). All these procedures require incubation in a culture medium to produce an adequate supply of microorganisms for various analyses at the end of the test. Apart from which, the conventional techniques use equipment that is not particularly low cost, making its employment difficult or unviable for widespread surveying, in other words, for detection/monitoring of microorganisms in more than one place simultaneously.
There are other more modern procedures concerning biological detection, such as: radiometry, electrochemicals, chromatography, chemiluminescence, pulse field electrophoresis and fluorescence. Concerning the techniques mentioned, there are some practical restrictions such as, for example, their success is highly dependent on the quantity of bacteria that can be concentrated in the test sample. This procedure, generally, requires a minimum of 10
4
bacteria. In molecular reactions, the test procedures are particularly liable to cross contamination by other molecules or molecular fractions.
In addition, optical preventive techniques can be employed, aiming the elimination of pathogenic microorganisms, highlighting, for example, the use of ultraviolet light as a germicide, avoiding the infection of a determined environment or a material medium. On the other hand, the medical knowledge for fighting pathogenic microorganisms that had already infected the human body, especially those originating from hospital infection, food poisoning and water contamination, is vast but incomplete. Such microorganisms may also become resistant to any known drug due to their possible biological mutations. Recently, some success has been achieved with patients infected with these microorganisms using photochemical drugs activated by electroluminescent semiconductor diodes of high optical power with the correct wave length, permitting the total elimination of these microorganisms, without, in principle, harming the patient. This is the case, for instance, of the procedures recently developed and described by Pearce et al (H Pearce, M. Messager and J. Y. Maillard. “Effect of biocides commonly used in the hospital environment on the transfer of antibiotic-resistance genes in
Staphylococcus aureus
”. J.Hosp.
Infect. 43.2, pp. 101-107, 1999).
The optical surveying of microorganisms, which is the object of the invention herein, finds its place between the preventive techniques for the reduction/elimination of microorganisms and the techniques that aim to eliminate pathogens that have already infected the patients.
The essential characteristics of any biological sensor are its selectivity, sensitivity, resolution and response time, characterized by reactive recognition based on the type of test and the choice of detection technique. At a second level, there must be a biological surveying technology available that is robust, practical and of low cost, so that it may be employed in the field. Presently, various techniques and correlated devices are available, many of these are still at laboratory level whilst others are commercial, all aiming the detection and monitoring of microorganisms.
Microscopy, as already mentioned, constitutes a fundamental analysis tool in microbiology, not only for the detection/monitoring of microorganisms, but also for the basic study of these. In the same way, there is a method of surveying bacteria involved in processes of hospital infections presently in use, known as pulsed field electrophoresis in, which is capable of tracking with precision the microorganisms involved, mapping and evaluating the level of environmental impact. However, it presents the disadvantage of the analysis taking approximately 7 to 14 days, as described by Birron and Lai (B. Birron and E. Lai. “Pulsed field electrophoresis: a practical guide”. Academic Press, San Diego, 1993).
With the aim of undertaking microbiological detecting and monitoring in an automatic and selective manner, the concept of the biosensor arises. A biosensor may be understood as a discreet electrical and/or optical component built based on the integration of biological materials with inorganic materials. A biosensor, in practice, is therefore capable of producing an analog electrical or optical signal when placed in contact with some specific subject, whether by its presence or any chemical-biological alterations occurring from it. A biosensor may be considered as a biologically active element, however, it requires connection, in some form, to a larger configuration, so that the electrical or optical analog can be adequately demodulated. The set-up thus formed is called a biological sensor. Fiber optics, in a general manner, may be used in the construction of biosensors, which means that through some appropriate technique, biological materials should be integrated to the sheath or core of the fiber (generally of glass or plastic) composing, therefore, an optical biosensor
Ferreira Aldo P.
Ribeiro Ricardo M.
Werneck Marcelo M.
Fundacao Oswaldo Cruz (Fiocruz)
Nixon & Vanderhye PC
Sanghavi Hemang
LandOfFree
Method and device for the detection of microorganisms by... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for the detection of microorganisms by..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for the detection of microorganisms by... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3242903