Karpas.doc

DIAGNOSIS OF VAGINAL INFECTIONS
BY ION MOBILITY SPECTROMETRY
acquisition and processing automatically and provides the gynecologist with a recommended Gdalevsky1, Boris Tilman1and Avi Lorber1 diagnosis. Q-Scent has developed a rapid, accurate and inexpensive method for diagnosing Center, Rotem Industrial Park, Arava 86800. common vaginal infections from the mobility spectrum. To date the method has been applied to diagnose several hundred samples in Israel Amino-acids are the building blocks of all living Key words: IMS, biogenic amines, diagnostics, matter and are thus present in any material of biological origin. In organisms and plants biogenic amines are formed by degradation of amino-acids through microbial and enzymatic The inherent selectivity of atmospheric pressure processes. Among those compounds are amines, ionization processes plays an important role in determining the applications of ion mobility trimethylamine (TMA), putrescine, cadaverine, spectrometry (IMS), as the final ionic products histamine, spermidine, etc. The volatile and do not usually reflect the true composition of the semi-volatile biogenic amines that emanate from samples of vaginal discharge were measured by gainfully deployed mainly in applications where ion mobility spectrometry (IMS). The samples particularly in the detection of illicit drugs, gynecologist during a standard examination or explosives or toxic chemicals, mainly monitoring after the patient had specific complaints of vaginal pruritus. A correlation was found relatively simple applications require an ability between vaginal infections, like bacterial to control the ionization processes so that the vaginosis (BV), candidiasis (yeast infection) and target analytes will be preferably ionized and trichomoniasis, and the types and quantities of reduce interference that may be caused by other biogenic amines in these samples. A dedicated compounds in the sample. In many cases a reagent is added in order to modify the gas-phase The formation of their degradation products ion chemistry. The use of this reagent may be to continuously takes place during the life of the enhance the formation of ions from the target organism and after its death. Biogenic amines compounds, alter the product ions that are often have highly descriptive names, indicative formed from the analyte, keep the background of their origin: putrescine – found in putrid spectrum simple and serve as a marker for the matter, cadaverine - from cadaver, spermidine mobility scale and correct performance of the Vaginitis is the term used to describe different types of vaginal infections [6]. The three most affinity and are therefore amenable to detection common types are bacterial vaginosis (BV), by IMS, but despite that they have not found a candidiasis (yeast infection) and trichomoniasis. broad application window [1]. This is somewhat These should not to be confused with more surprising, considering the toxicity of most infamous sexually transmitted diseases (STDs) amines and their widespread importance in such as chlamydiasis, syphilis and gonorrhea. A industry, commerce and health related issues. vaginal infection may occur when the balance Several IMS publications focused on aspects of between lactobacilli (“friendly” or “good” pure research [2], but only a few, with the microorganisms) and pathogens is disturbed due exception of drug detection, were concerned with to medication (antibiotics are notorious practical potential applications [3-5]. Working promoters of yeast infections), personal hygiene with amines has its own problems: due to their (lack of cleanliness or too frequent douching), polarity they tend to get absorbed on surfaces personal stress or several other reasons. creating difficulties with sample introduction Treatments for these infections are quite systems and "memory effects" as well as having effective, if administered correctly, and the a large variety in their volatility. Biogenic natural balance may be restored within a few amines are produced when DNA, peptides and days. The main problem is that the symptoms (pain, itching, irritation, unpleasant discharge) chemical, microbial and enzymatic processes. are quite similar for these three infections, as Amino-acids are present in all types of biological well as for several problems arising from materials: living organisms and microorganisms allergies or physical factors, so that diagnosing as well as tissues of dead organisms and plants. the correct cause is a requisite for assigning the A cotton swab with a sample of vaginal fluid was collected by the gynecologist during a routine In the present work we wish to report on a novel, examination and stored in a sealed test tube until rapid and inexpensive method for diagnosing the analysis time. It was then placed in a vaginal infections through the measurement of disposable vial and connected to the IMS biogenic amines by IMS. This may be regarded introduction system. The vapors of the biogenic as the harbinger for a whole new area of amines were introduced into the drift tube from applications for IMS technology in the medical the sample container with a stream of clean air. and diagnostic fields, as well as other areas that The amines that were formed in the biological involve determination of amines and biogenic matrix could emanate spontaneously from the sample, but the process was considerably enhanced with the addition of a few drops of an alkaline solution. Heating the sample may be also used to enhance the release of vapors, prototype ion mobility spectrometer with a particularly of semi-volatile compounds. 63Ni ionization source was used in the present A dedicated software package was developed in work. The instrument was described in detail order to assist the physician in arriving at the previously [7]. In order to control the ion correct diagnosis (even without any knowledge of IMS technology). The mobility spectrum was nonylamine was selected as a reagent gas, computer. After the analysis was completed, reactant ion. This reagent is particularly typically within a 1.5 minutes, there were about suitable as its proton affinity is high enough 90 such spectra that could be displayed. For to limit the formation of ions from interfering each of the major ions (trimethylamine TMA, compounds present in the complex biological putrescine, cadaverine, spermidine/spermine and matrix while it is below that of the main nonylamine) a single ion monitoring curve, target analytes and the reduced mobility of depicting the change in intensity with time, was protonated nonylamine is significantly lower also displayed. Based on “expert rules” the data than that of the analyte ions, so that spectral was used to derive the correct diagnosis, which was then displayed for the benefit of the and infected cases: no false negatives (out of 23 BV, 3 Trich, 3 mixed) and only two false Typical spectra for a healthy patient with “normal” vaginal discharge and for a patient with The “traditional” applications of ion mobility bacterial vaginosis (BV) are displayed in Figure spectrometry (IMS) technology include, as noted 1. Note the large decrease in the intensity of in the brochure for the ISIMS 2002 meeting, nonylamine and large TMA in the patient with detection of controlled substances (explosives BV, compared to the healthy patient. Also note and drugs, mainly), toxic chemicals in general that while heating has only a small effect on the and particularly chemical warfare agents as well sample of the healthy patient, it leads to a as a few applications that can still be regarded as decrease in the TMA intensity and appearance of “exotic” like on board the space shuttle or the semi-volatile amines (putrescine and electrospray and laser desorption. In the present cadaverine) in the sample with BV infection. work, a new area for IMS applications is Figure 2 shows the principal component analysis proposed: investigation of biological and (PCA) plot of the results from 97 samples physiological systems for medial and diagnostic collected and analyzed in a US field test. The purposes. One of the first such applications - the circles represent the patients diagnosed as BV- use of IMS for diagnosing common vaginal negative (healthy) according to the standard infections - has been successfully demonstrated method (Amsel Test [6]), the diamonds are in several hundred samples of vaginal fluid in samples diagnosed as BV-positive, squares diagnosed as trichomoniasis positive and triangles as mixed (BV and trich) infections. The IMS clearly differentiates between healthy INTENSITY (Volts)
DRIFT TIME (ms)
Principle Component Analysis of Detroit Field Test
Second Principle Component -0.3
First Principle Component
1. a) G. A. Eiceman, and Z. Karpas, “Ion mobility time-of-flight mass spectrometry 2. a) Z. Karpas, Ion mobility spectrometry 6. J. D. Sobel, Vaginitis – Review article, 7. Z. Karpas, A. Lorber, B. Tilman and R. 204; c) Z. Karpas, S. E. Bell, Y-F. Wang, 3. A. P. Snyder, C. S. Harden, D. M. Davis, portable GC-IMS for the determination of 4. L. M. Matz and H. H. Hill, Jr., Evaluating

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