Bacterial Lab Diagnosis | Bacterial Culture Media, Microscopy, Serology and Molecular Diagnostics (YouTube Video Transcript)

(00:00:00) Your YouTube transcript will appear here (00:00:00) Asalamaikum friends, welcome back to the (00:00:02) channel. Today we're going to talk about (00:00:04) bacterial lab diagnosis. This is really (00:00:08) crucial in understanding which infection (00:00:10) is caused by which bacteria either our (00:00:12) normal fluoride is involved or there's (00:00:14) some foreign bacteria that got into our (00:00:16) body and is responsible for causing (00:00:18) infection. But before starting the (00:00:20) lecture, I'd like to tell you guys that (00:00:21) these videos are meant for educational (00:00:22) purposes. Things and treatments may (00:00:24) change with time. If I get wrong or miss (00:00:26) anything, your input is always welcomed (00:00:28) in the comments section. Grab a cup of (00:00:31) tea and let's get started. Bacterial lab (00:00:33) diagnosis. (00:00:35) Bacterial lab diagnosis is an important (00:00:37) tool in the diagnosis and treatment of (00:00:40) bacterial infections and is often used (00:00:42) in conjugation with other diagnostic (00:00:44) methods such as clinical examination and (00:00:47) imaging tests. The process of using (00:00:49) laboratory methods to identify bacterial (00:00:52) infections. Bacterial lab diagnosis (00:00:54) involves analysis of the sample such as (00:00:57) blood, urine, sputum and stool. And (00:00:59) there might be some other samples but (00:01:01) for your ease I've put just these (00:01:03) samples. It identifies bacteria that (00:01:05) responsible for causing the infection (00:01:07) and determines their susceptibility to (00:01:10) different antibiotics. It means that it (00:01:12) guides in the treatment. Some bacterial (00:01:16) strains are resistant to certain (00:01:17) antibiotics. So by doing a bacterial (00:01:19) layer diagnosis we will know that which (00:01:22) antibiotic is not useful against this (00:01:24) bacteria. So we'll switch to another (00:01:26) bacteria to treat that infection. (00:01:27) Lecture outline I've introduced you guys (00:01:29) to the bacterial lab diagnosis. Now we (00:01:31) are going to have a deep look at the (00:01:33) methods and at the end as usual we'll (00:01:35) review the lecture. Laboratory (00:01:37) diagnosis. The laboratory diagnosis of (00:01:39) infectious diseases include microscopic, (00:01:41) culture based, imunologic or cerologic (00:01:44) and molecular which include nucleic acid (00:01:46) and protein based tests. Bacterial lab (00:01:49) diagnosis involve following methods. But (00:01:51) prior to doing any of the methods, we (00:01:54) will collect the sample. This step is (00:01:56) called collection of specimen. It is (00:01:58) followed by microscopy. If microscopy is (00:02:02) uh enough to diagnose an infection or (00:02:06) tell us the cause of that infection then (00:02:08) we'll not go further and if it fails to (00:02:11) do so then we'll go for culture. Same (00:02:13) goes for culture. If culture fulfills (00:02:15) our requirement we'll stay with culture. (00:02:17) If culture doesn't fulfill our (00:02:19) requirement we'll go for cerology. If (00:02:21) cerology fails to fulfill our (00:02:22) requirement then we'll go for molecular (00:02:24) diagnostics. (00:02:25) Cerology collection of specimen. The (00:02:27) first step in the lab diagnosis of the (00:02:30) bacteria, we'll collect a sample from (00:02:33) the body site. There are two types of (00:02:35) body sites. One is sterile, one is (00:02:36) non-sterile. Sterile is something like (00:02:38) that is not contaminated with any of the (00:02:41) foreign uh body foreign organism. If we (00:02:44) are taking a sample from urinary (00:02:46) bladder. So um urinary bladder is (00:02:48) sterile from inside. There's no bacteria (00:02:50) that is going to um make this area (00:02:53) contaminated or our sample contaminated. (00:02:56) nonchal for example we are collecting a (00:02:59) sample from a wound on a skin cut so (00:03:01) there might be certain foreign particles (00:03:03) like soil dust and pathogens from the (00:03:07) environment atmosphere and also uh from (00:03:09) the skin around the wound so this is the (00:03:12) non-sterile body side and the urinary (00:03:14) bladder in that example I mentioned was (00:03:16) the sterile body side then we will (00:03:19) collect an adequate quantity of that (00:03:21) sample or the contamination from the (00:03:23) normal flora if it is contaminated with (00:03:26) to normal fl it will be difficult for us (00:03:27) to diagnose whether the normal flare (00:03:29) responsible for causing that infection (00:03:31) or the infection is caused by the (00:03:33) organism present in the sample integrity (00:03:36) of that sample is not compromised during (00:03:38) transport specimen is handled carefully (00:03:41) and ancillary information which means (00:03:43) supplementary information is also (00:03:45) provided there are different specimens (00:03:47) collection site um I've mentioned (00:03:49) following blood throat sputum CSF stool (00:03:55) urine genital tract, wound and abscess. (00:03:58) Microscopy. Prior to knowing what is (00:04:00) microscopy, we should know what is a (00:04:02) microscope. Microscope is a device that (00:04:04) magnifies means zooms in an image of an (00:04:08) object so that it can be examined in (00:04:10) more detail and by using microscopes to (00:04:14) view and investigate objects that are (00:04:16) invisible to human eye or naked eye. (00:04:18) This process is called microscopy. Types (00:04:20) of microscopes. There are different (00:04:21) types of microscopes each with their own (00:04:23) advantages and limitations. Number one (00:04:26) is optical microscope. Optical (00:04:29) microscopes use visible light to magnify (00:04:31) specimens image. Cells, tissues and (00:04:34) microorganisms as well as small (00:04:36) structures and particles can be (00:04:38) visualized using them. The second one is (00:04:41) electron microscope. (00:04:43) These microscope do not use light but (00:04:47) still they achieve a higher (00:04:48) magnification than optical microscope (00:04:50) and they are frequently used to examine (00:04:52) the ultrasound of cells and tissues. (00:04:55) Scanning probe microscopes in order to (00:04:58) image surfaces and material with (00:05:00) extremely high resolution scanning probe (00:05:03) microscopes use a physical probe to scan (00:05:05) the specimen's surface. What is the (00:05:07) method of microscopy? Prior to any (00:05:09) procedure as I mentioned we will collect (00:05:10) the samples. The specimen is collected. (00:05:13) After the collection of the specimen, (00:05:15) stain the specimen using the appropriate (00:05:16) procedure. For example, gram stain or (00:05:19) acid fast stain. If bacteria are seen in (00:05:22) gram stain, then their shape for example (00:05:24) cooxy rod size arrangement for example (00:05:28) chains or cluster and whether they are (00:05:30) gram positive or negative or acidfast (00:05:33) are observed. And it is also important (00:05:37) to to know the number either one or more (00:05:39) than one type of bacteria or more than (00:05:41) one bacteria involved. Microscopy has (00:05:44) advantages of texonomy classification (00:05:47) cuz uh when we go for staining in gram (00:05:49) stain we will get to know are there's (00:05:51) gram positive or is gram negative and in (00:05:54) acid first we'll get to know which (00:05:56) bacteria is it. I've got a detailed (00:05:59) video on bacterial texonomic (00:06:01) classification. It link is in the (00:06:02) description or maybe in the top right (00:06:04) corner. and also empiric therapy is (00:06:06) done. What is empiric therapy? It refers (00:06:09) to antibiotics that are administered (00:06:11) during the period prior to receipt of (00:06:13) blood culture and antibiotic (00:06:15) susceptibility test results. There is (00:06:18) only one disadvantage that microscopy (00:06:20) has and it is that it is not sufficient (00:06:23) to identify an organ culture. A process (00:06:26) for identifying and describing the (00:06:28) species of bacteria in laboratory grown (00:06:30) samples. There are some terms that I (00:06:32) would like to mention prior to telling (00:06:34) you about the method of how to do (00:06:36) culture. Number one is medium. Its (00:06:39) plural is media. It is any preparation (00:06:42) that contains nutrients essential for (00:06:44) bacterial growth. As in this picture, (00:06:46) you can see this is one medium. This is (00:06:49) another. This is another. And these (00:06:50) three together are called media. And (00:06:55) they've got essential nutrients that are (00:06:57) required for bacterial growth. Culture (00:06:59) medium. A medium that has been (00:07:01) successfully inoculated with bacteria. (00:07:03) Inoculation of media. It means (00:07:06) introduction of infected material to the (00:07:08) medium for cultivation of organism (00:07:10) present in that material. Major types of (00:07:13) culture media. One is selective and the (00:07:16) other one is differential. The selective (00:07:18) media containing compounds that only (00:07:21) allow certain bacteria to grow. For (00:07:23) example, antibiotics, salts or dyes. On (00:07:27) the other hand, differential media is (00:07:31) differential because they contain other (00:07:33) compounds that allow only one type of (00:07:35) bacteria to be distinguished from (00:07:37) another based on biochemical reaction. (00:07:40) For example, detecting hemolysis on (00:07:42) blood agar plates or pigment formation. (00:07:44) But in some places you'll also find the (00:07:47) classification of culture media based on (00:07:50) physical state and composition. (00:07:52) According to physical state, culture (00:07:54) media is classified into liquid and (00:07:57) solid. Liquid media is fluid in nature (00:08:00) and it is usually placed in test tubes. (00:08:02) It is also called broths. For example, (00:08:05) nutrient broth, tptic soy broth, phenol, (00:08:09) red carbohydrate broth. And solid media (00:08:12) is prepared by adding solidifying agents (00:08:14) like gelatin and agger to liquid medium. (00:08:17) For example, Newton agger, blood agar, (00:08:20) mcconiki agger and chocolate agger. And (00:08:22) according to composition, culture media (00:08:24) is classified into simple media which (00:08:27) contains only basic substances such as (00:08:29) nitrogen, carbon and minerals. For (00:08:32) example, nutrient broth, neutron agar, (00:08:35) pepone, water. And the second one is (00:08:37) enriched media. Enriched media is called (00:08:40) enriched because it has got some (00:08:42) enriched material like blood, serum or (00:08:46) aesthetic fluid. Aesthetic fluid is (00:08:48) actually the fluid present in abdomen um (00:08:51) during escites mainly related to liver (00:08:53) conditions and this fluid may be serum (00:08:56) aesthetic fluid or blood is added to the (00:08:59) medium required for proper growth of (00:09:01) some bacteria for example blood agar (00:09:04) chocolate agar. The third one is (00:09:06) differential media. We've discussed that (00:09:08) we've discussed selective media. Um the (00:09:11) example of differential media is McConi (00:09:13) medium and the selective media is (00:09:16) Loenstein Johnson's medium. The final (00:09:18) one is media for biochemical reactions. (00:09:20) It is used to detect different (00:09:22) biochemical reactions produced by (00:09:24) different organisms. For example, (00:09:25) thimman citrate media. Now we are going (00:09:27) to have a look at commonly used (00:09:29) bacterial logic ag. There are three (00:09:31) columns in this table. First one is (00:09:33) showing the name of the aga. Second one, (00:09:35) it will be telling which bacteria is (00:09:37) isolated on that agar. And the third one (00:09:40) is telling the function or properties of (00:09:42) the egg. I'll explain just two or three (00:09:44) and we'll leave the rest to you guys. (00:09:46) It's not difficult. Don't worry. First (00:09:48) egg is blood. Various bacteria are (00:09:51) isolated in that ager and it is used to (00:09:55) detect himis. The second one is it is an (00:09:58) Italian word. It is borded jango gango. (00:10:03) I don't know how it is pronounced (00:10:04) because I don't know Italian language (00:10:06) and I found that on internet that it is (00:10:09) pronounced jango at some places and (00:10:12) gango at some places and it is used for (00:10:16) the isolation of bordellopertus bacteria (00:10:19) and it is used to detect increased (00:10:22) concentration of blood which allows the (00:10:24) growth. The third one is charcoal yeast (00:10:27) extract. The bacteria isolated on that (00:10:30) tagger is legionella numopila and it has (00:10:33) got an amazing property that increased (00:10:35) concentration of iron and cysteine (00:10:36) allows growth. Let me have a look at (00:10:40) another one. Okay, let's look at (00:10:43) Laurenstein Jensen. The microacterium (00:10:46) tuberculosis (00:10:48) is isolated on that. It selects against (00:10:51) gram positive bacteria in respiratory (00:10:53) tract flora and contains lipids required (00:10:56) for growth. Let's start talking about (00:10:58) the cultures. The first one is blood (00:11:00) cultures. It is performed in the (00:11:03) following cases. Subpsis, endocarditis, (00:11:06) osteomiitis, menitis and pneumonia. The (00:11:09) bacteria most frequently isolated from (00:11:11) blood cultures are two gram positive (00:11:13) coxy. The first one is teflocus orius. (00:11:16) The second one is traptocus pneumonia (00:11:19) and three gram negative rods. The first (00:11:21) one is isia. The second one is cluba (00:11:24) pneumonia. And the third one is (00:11:26) sunamonus origigosa. Certain pathogenic (00:11:28) fungi including yeast, candida species (00:11:30) and cryptocus neoformance and molds can (00:11:34) also be isolated from blood cultures. (00:11:37) But we are not talking about fungus in (00:11:40) this video cuz this is dedicated to (00:11:42) bacterial lab diagnosis. The method of (00:11:44) blood cultures. For blood cultures, the (00:11:46) site for puncture must be cleansed by an (00:11:49) antiseptic to prevent contamination by (00:11:51) members of the flora of skin. usually (00:11:53) stafloccus epidermis and decrease the (00:11:56) risk of infection related complications. (00:11:58) The blood obtained is aided to a rich (00:12:00) growth medium in a bottle that contains (00:12:03) an indicator for carbon dioxide (00:12:05) production. Standard practice is to (00:12:07) inoculate 10 ml of blood in each of two (00:12:09) bottles per culture set with one bottle (00:12:12) incubated anorobically and one bottle (00:12:14) aerobically. Production of carbon (00:12:16) dioxide within the bottle indicates that (00:12:18) organism metabolism and growth have (00:12:21) occurred. Once growth occurs, gram (00:12:24) [clears throat] stain subculture and (00:12:26) antibiotic sensitivity tests are (00:12:28) performed. In some hospitals, molecular (00:12:30) methods are also used to identify the (00:12:32) organism. Next ones are the throat (00:12:34) culture. Throat cultures are performed (00:12:35) in dtheria, fngitis, konoal farangitis (00:12:39) and oral thrush caused due to candida (00:12:41) and they are used to detect the presence (00:12:43) of group A betaolytic strapto coxy these (00:12:46) straptococcus pyiogens. GR stain is (00:12:49) typically not done on throat swab (00:12:51) because it is impossible to distinguish (00:12:53) between the appearance of normal flora (00:12:55) strapto coxy and streptococcus pyiogens (00:12:58) method. When this specimen is obtained, (00:13:00) the swab should not touch only the (00:13:03) posterior fairings but also both tonsils (00:13:05) and tonsular fosi as well. Material on (00:13:08) the swab is inoculated onto a blood ager (00:13:11) plate and stre to obtain single (00:13:14) colonies. If colonies of beta himolytic (00:13:16) staptoxy are found after 24 hours of (00:13:19) incubation at 35° C, a bassy tracing (00:13:24) disc is used to determine you know (00:13:25) whether the organism is likely to be a (00:13:27) group A strap caucus. If growth is (00:13:30) inhibited around the disc, it is group A (00:13:32) strap caucus. If not, it is a non-group (00:13:35) A betaolytic streptococcus. Futum (00:13:37) cultures these are performed in the (00:13:39) cases of pneumonia, pulmonary (00:13:40) tuberculosis and lung absess. They're (00:13:43) commonly used to detect septocus (00:13:45) pneumonia, stafylocus arius, clapsiala (00:13:47) pneumonia, pseudomonus origigosa, (00:13:50) mopopplasma and legionella pneumon (00:13:52) method. Prior to doing anything else, we (00:13:55) are going to collect what sample. So (00:13:57) sample of sputum is collected. It is the (00:13:59) sputum not the saliva or nazopharangial (00:14:02) secretions from the upper airway. Then (00:14:04) it is stre on blood agar plate and the (00:14:07) presence of colonies on the plate is (00:14:09) revealed. Culture of sputum on blood (00:14:11) agar can reveal the presence of colonies (00:14:13) with identification established using (00:14:16) various cerologic or biochemical tests (00:14:18) or by maldito. (00:14:21) It is abbreviated as matrix resisted (00:14:23) laser disorption or ionization time of (00:14:26) flight. Cultures of myoplasma are (00:14:28) infrequently done. Diagnosis is usually (00:14:31) confirmed by a rise in antibbody (00:14:33) tighter. If leional and pneumonia is (00:14:36) suspected, the organism can be cultured (00:14:38) on charcoal yeast ago which contains the (00:14:41) high concentrations of iron and sulfur (00:14:43) which are required for growth. If (00:14:45) tuberculosis is suspected and acidf (00:14:47) stain is done immediately and the sputum (00:14:50) cultured on special media which are (00:14:52) incubated for at least 6 weeks in (00:14:56) diagnosing the aspiration pneumonia and (00:14:57) lung absesses culturing for anorobic (00:15:00) bacteria is important. CSF cultures or (00:15:02) cerebral spinal fluid cultures. These (00:15:04) are performed in the following cases. If (00:15:06) it is bacteria responsible for causing (00:15:08) the disease and diseases are menitis, (00:15:12) meniophilitis, (00:15:13) transfer myelitis, CSF specimens from (00:15:16) tissuecentric cases including (00:15:17) encphilitis, brain absess and subdural (00:15:20) empa may negative cultures and for one (00:15:23) fungus and that is cryptocogus (00:15:25) neopformance. They're commonly used to (00:15:26) detect these encapsulated organisms. (00:15:29) Nisseria mangitus septtocus pneumonia (00:15:32) and hemophilus influenza method prior to (00:15:35) doing anything gal sample is collected. (00:15:37) Then it is centrifuge. Then what (00:15:39) happens? It is taken through a staining (00:15:41) procedure either gram strain or acid (00:15:43) fast stain. Then the gram stain smear of (00:15:46) the sediment of the centriuute sample (00:15:48) guides the immediate empirical therapy. (00:15:50) The flu should thus also be cultured on (00:15:52) special media and the cultures held for (00:15:54) a minimum of 6 weeks and molecular (00:15:56) methods are also used to identify these (00:15:58) organisms and we are going to discuss (00:16:00) what are these methods at the end of (00:16:01) this week. And for the fungus cryptocus (00:16:03) neopformance it is a cause of menitis (00:16:06) particularly in human immuno deficiency (00:16:08) virus infected patients. Um the India (00:16:11) ink test was performed in the past but (00:16:13) in present most labs use the latex a (00:16:17) glutination test that is for the (00:16:20) cryptocus neoiforins um it's cryptocal (00:16:22) antigen and that is done on CSF as a (00:16:25) more specific and sensitive test stool (00:16:28) cultures these are performed in severe (00:16:29) and persistent diarrhea nocomial (00:16:32) diarrhea and interocolitis and also the (00:16:35) bloody diarrhea it is commonly used to (00:16:37) detect chagela salmonila campilobacter (00:16:40) Eoli partially it's 0157 (00:16:43) strains and claustrdium deficile the (00:16:46) method is that feces are collected (00:16:48) specimen is processed within 2 hours and (00:16:50) plates used for different media are (00:16:52) mecconic aaggerosin methylene blue agar (00:16:55) campy cva and cro medium mikonis sobbl (00:16:59) medium and also molecular methods are (00:17:02) used for these bacteria that are present (00:17:04) in feces responsible for causing (00:17:05) diseases urine cultures urine cultures (00:17:07) are performed in following cases like (00:17:09) pylo Nephritis and cyitis and these are (00:17:12) commonly used to detect escaricia coli (00:17:14) which is the common cause of UTI then (00:17:17) interobacttor proteas and interocous (00:17:19) vicalis method is to obtain a specimen (00:17:21) in a container or by using suprapubic (00:17:24) aspiration and catheterization. Let me (00:17:26) tell you something really cool here. (00:17:28) Urine in the bladder of a healthy person (00:17:30) is sterile but it acquires organism of (00:17:32) the normal flora as it passes through (00:17:34) the distal portion of the urethra. To (00:17:36) avoid these organisms, a mid-stream (00:17:38) specimen avoided after washing the (00:17:40) external orifice is used for urine (00:17:42) culture. In special situations, (00:17:45) subraubic aspiration and catheterization (00:17:47) may be required to obtain a specimen. (00:17:50) How we are going to form the urine (00:17:51) cultures? We'll go for a calibrated loop (00:17:54) that holds 0.001 (00:17:56) ml of urine and can be used to streak (00:17:58) the culture. The second one is serial (00:18:00) 10fold dilutions that can be made and (00:18:03) sampled from dilution streaked. And the (00:18:05) third one is a screening procedure. It (00:18:07) involves an aggreged paddle that is (00:18:09) dipped into the urine. After the paddle (00:18:11) incubated, the density of the colonies (00:18:14) is compared with standard charts to (00:18:16) obtain an estimates of concentrations of (00:18:19) the bacteria in the urine. Something (00:18:21) important about urine cultures. Culture (00:18:23) to be done within first hour of (00:18:25) collection. Urine to be stored in (00:18:27) refrigerator for not more than 18 hours (00:18:29) at 4° C. It is commonly accepted that a (00:18:32) bacterial count of at least 100,000 per (00:18:35) ml must be found to conclude that (00:18:38) significant bacteria is present in the (00:18:40) urine and in asymptomatic patient. There (00:18:43) is evidence that a bacterial count as (00:18:45) low as thousand per ml is significant in (00:18:48) symptomatic patients. Dental tract (00:18:50) cultures these are performed in the (00:18:52) cases of abnormal discharge aides (00:18:54) sexually transmitted diseases non (00:18:56) gonoccal urethritis and cervicitis and (00:18:59) they are commonly used to detect niseria (00:19:01) gonari and clamidia trachomeatus. The (00:19:04) method is to obtain a specimen and it is (00:19:06) obtained by swabbing um by swabbing the (00:19:09) urethral canal for men and cervix for (00:19:12) women and anal canal for both men and (00:19:14) women and then it is streaked on the (00:19:16) plate and is left for the growth and (00:19:19) when the bacteria grows. And here we go (00:19:21) for our diagnosis. Plates being used in (00:19:23) genital tract cultures for niceria (00:19:25) gonari the martin chocolate agar plate (00:19:28) is used and for clamdia trachomeatus the (00:19:30) cultures of human cells or the cultures (00:19:32) of yolk sex of embryionated eggs are (00:19:34) used because the trapony paladium the (00:19:36) agent of syphilis cannot be cultured (00:19:39) diagnosis is made primarily by cerology (00:19:41) and sometimes by microscopy wound and (00:19:44) absess cultures these are performed in (00:19:45) the following cases in the brain (00:19:47) obsesses lung obsesses and abdominant (00:19:49) obsesses and in case of wound wound (00:19:52) infections, traumatic open wound (00:19:53) infections, surgical wound infections (00:19:55) and human bites. And they're commonly (00:19:57) used to detect the following bacteria. (00:19:59) Bacteris fragelis, rampositive coxy, (00:20:02) asorius, espiogens, claustrdium (00:20:05) preferring, staff, straptooxy, propion (00:20:08) bacterium, acnes, wired staptoxy, (00:20:11) straptocaucus angossis, probatella and (00:20:14) fuso bacteria. The method is to collect (00:20:16) a specimen in the collection tubes and (00:20:18) then transport it to the culture and (00:20:19) then streak that over the culture plate. (00:20:22) When culture is negative, immunologic or (00:20:24) molecular methods are used. Imunologic (00:20:26) methods are which one? The cerologic (00:20:28) method. How to diagnose a bacterial (00:20:30) infection when the culture is negative. (00:20:33) Detect the antibbody in the patient's (00:20:34) serum. Detection of immunoglobulin IGM (00:20:38) antibbody indicates a current infection. (00:20:40) A single IGG antibbody titer is (00:20:43) difficult to interpret because it is (00:20:46) unclear whether it represents a current (00:20:48) infection or the previous infection. In (00:20:50) certain diseases, a single titer of (00:20:53) sufficient magnitude can be used as (00:20:55) presumptive evidence of a current (00:20:57) infection. Another thing that we can do (00:20:59) when the culture is negative is to (00:21:01) detect antigen in patient specimen. Use (00:21:03) non antibbody to detect presence of (00:21:05) antigens of the organisms. For example, (00:21:07) fluorescent antibbody to detect antigens (00:21:10) in tissue, latex egg glutination to (00:21:12) detect capsular polysaccharide antigens (00:21:14) in spinal fluid. The third thing that we (00:21:17) can do when culture is negative is to (00:21:18) detect nucleic acids definitely in the (00:21:21) patient serum and then use polymerase (00:21:24) chain reaction the PCR and DNA probes to (00:21:26) detect the DNA or RNA of the organism. (00:21:29) And now we are done with the cultures. (00:21:31) Let's talk about cerologic methods or (00:21:33) cerology. It is a process to detect (00:21:35) antibodies in a patient's blood that are (00:21:37) specific to bacteria causing the (00:21:39) infection. There are two basic (00:21:42) approaches for that. Number one is using (00:21:44) non antibbody to identify the (00:21:46) microorganism and the number two is (00:21:48) using non antigen to detect antibodies (00:21:51) in the patient's serum. Methods there (00:21:53) are two methods to do that. Number one (00:21:55) is identification of an organism with a (00:21:57) known anti- serum. The following four (00:22:00) tests are involved in this one. The (00:22:02) first one is side aglutination test. It (00:22:04) is the anti-era that can be used to (00:22:07) identify salmonila and chagala by using (00:22:09) aglutination mean clumping of unknown (00:22:12) organism. The second one is latex (00:22:14) aglutination test. The latex beads (00:22:17) coated with specific antibbody are (00:22:18) aglutinated in the presence of (00:22:20) homologous bacteria or antigen. This (00:22:23) test is used to determine the presence (00:22:24) of capsular antigen of the yeast (00:22:26) cryptocus neoiforance. The third one is (00:22:29) Eliza E L I Z A and it stands for enzyme (00:22:33) linked to immunosorbent essay. If this (00:22:35) test a specific antibbody to which an (00:22:37) easily asset enzyme has been linked is (00:22:40) used to detect the presence of (00:22:42) homologous antigen. This test is useful (00:22:44) in detecting a wide variety of bacterial (00:22:47) viral and fungal infections. The fourth (00:22:49) one is floroscent antibbody test. A (00:22:51) variety of bacteria can be identified by (00:22:54) exposure to non- antibbody labeled with (00:22:56) fluorescent dye which is detected (00:22:58) visually in ultraviolet microscope. The (00:23:01) second method in cerologic methods is (00:23:04) identification of serum antibodies with (00:23:06) known antigens. It includes side or tube (00:23:09) a glutination test. In this test serial (00:23:12) tofold dilutions of a sample of patient (00:23:15) serum are mixed with standard bacterial (00:23:17) antigen suspension. The highest dilution (00:23:19) of the serum capable of aglutination is (00:23:21) the tighter of the antibbody. As with (00:23:24) most tests of the patient's antibbody, (00:23:26) at least a four-fold rise in the titer. (00:23:29) Tighter is actually the concentration of (00:23:30) antibodies in the blood. At least a (00:23:32) four-fold rise in the titer between the (00:23:34) early and the late samples must be (00:23:36) demonstrated for diagnosis to be made. (00:23:39) This test is used primarily to aid in (00:23:41) the diagnosis of typhoid fever, (00:23:42) brucyosis, plake, laptoposis and recial (00:23:46) diseases. The second method is cerologic (00:23:48) test for syphilis. As I mentioned (00:23:50) earlier, it is a detection of antibbody (00:23:53) in patient serum and is frequently used (00:23:55) to diagnose syphilis because trapony (00:23:57) paladium does not grow on laboratory (00:23:59) media. There are two kinds of tests. (00:24:02) Number one is the non-traonymal tests (00:24:04) and the second one is the traponymal (00:24:06) test. I'm not going to go in detail cuz (00:24:08) this will make this video too complex (00:24:10) guys. Okay. Now have a look at the cold (00:24:13) a glutination test. Patients with (00:24:15) myopplasma pneumonia infections develop (00:24:17) autoimmune antibodies that elglutinate (00:24:20) human red blood cells in the cold at 4° (00:24:23) C but not at 37° C. These antibodies (00:24:27) occur in certain diseases other than (00:24:29) micropplasma infection. This false (00:24:31) positive results can occur. Finally, we (00:24:34) are going to talk about molecular (00:24:35) methods. Molecular tests can detect the (00:24:38) presence of bacterial DNA, RNA or (00:24:40) protein in patient specimens. These (00:24:43) tests are both sensitive and specific (00:24:45) and they've become the diagnostic gold (00:24:48) standard for many infections. There are (00:24:50) two types of molecular methods. First (00:24:52) one is genomic test that includes (00:24:54) nucleic acid amplification test and the (00:24:56) second one is proteomic test that (00:24:59) includes the matrix resisted laser (00:25:01) disorption or ionization time of flight. (00:25:05) The specificity of these tests resides (00:25:07) in the ability of the DNA or RNA probe (00:25:10) to bind to DNA or RNA present only in (00:25:13) the bacteria to be identified. I know it (00:25:15) was too much knowledge in today's video. (00:25:17) So I'm going to review that by (00:25:19) summarizing it here. How to diagnose a (00:25:22) bacterial infection or the diagnosis of (00:25:24) bacterial infection. Prior to doing (00:25:26) anything else, we are going to do what? (00:25:27) We will obtain a specimen from the (00:25:29) infected side. Then we'll go for (00:25:31) microscopy. We'll stain this specimen (00:25:33) either with GR stain or acid V stain. (00:25:35) And if bacteria are seen then we'll (00:25:37) identify the type either scram positive, (00:25:40) negative or acid paths. Then its number, (00:25:42) shape, size and arrange and then we'll (00:25:44) go for the culture. Bacterial samples (00:25:46) are grown in laboratory to identify and (00:25:48) characterize the bacterial species. (00:25:50) There are two types of the culture that (00:25:52) is the selective and differential. For (00:25:53) example, urine culture, true culture and (00:25:55) blood culture. Cerology. It detects (00:25:58) antibodies in a patient's blood that are (00:26:00) specific to bacteria causing the (00:26:02) infection. Molecular methods. These (00:26:04) detect the presence of bacterial DNA, (00:26:06) RNA or protein in patients specimen. And (00:26:09) that's it for today's video. I hope you (00:26:11) guys enjoyed it. You've learned (00:26:12) something. If you've got any (00:26:13) suggestions, feel free to leave them (00:26:15) below in the comment section. And also, (00:26:17) if you want to connect with me on my (00:26:18) social media, I've got my Instagram, (00:26:20) I've got my Twitter, and I do upload (00:26:21) vlogs. I'll catch you soon. Till then, (00:26:24) asalamu alaykum.