Acid fast bacilli stain afb the following tests are available. Most samples that are submitted for acidfast bacilli afb testing are collected because the healthcare practitioner suspects that a person has tuberculosis tb, a lung infection caused by mycobacterium tuberculosis. Diagnosis of mycobacterial infections based on acidfast. Mycobacteria are called acidfast bacilli because they are a group of rodshaped bacteria bacilli that can be seen under the microscope following a staining procedure where.
Smear results will be recorded as positive for acidfast bacilli. This method is used for those microorganisms which are not staining by simple or gram staining method, particularly the member of genus mycobacterium, are resistant and can only be visualized by acid fast staining. Richardallan scientific acid fast bacillus blue and green. Detection of acid fast bacilli afb in stained and acid washed smears examined microscopically may provide the initial bacteriologic evidence of the presence of mycobacteria in a clinical specimen. Mycobacteriology laboratory manual world health organization. In acid fast stains, the phenol allows the stain to penetrate, even after exposure to decolourisors.
If you find that you have been suffering from the following symptoms, then you need to consult your physician right away and he would, after a physical examination, order a afb stain urine test. Acid fast bacilli questions and study guide quizlet. The acid fast bacteria afb stain kit microorganism stain is intended for use in the histological visualization of acid fast bacteria and tubercle bacilli. Acidfastness is a physical property of certain bacteria and cellular structures. Then smear from sputum is fixed by heat or alcohol. Not decolorized by acid after staining, as bacteria that retain dye after an acid rinse. Because of this feature, this stain is extremely helpful in identification in diseases caused by acidfast bacteria, particularly tuberculosis and leprosy. Carbol fuchsin stain, ziehlneelsen, combines phenol and basic fuchsin that works to permeate the lipoid capsule of acidfast organisms and renders them resistant to acid alcohol decolorization. A cold staining method for acidfast bacilli article pdf available in bulletin of the world health organisation 645. It is believed that only leprosy bacilli which stain with carbolfuchsin as solid acid fast rods are viable and that bacilli which stain irregularly are probably dead and degenerating. Pdf mycobacterium tuberculosis mtb detection using zielh. Diseases caused by acid fast organisms, mycobacterium, et al. Artisan acidfast bacillus afb stain kit english code ar162.
Neelsen zn and fluorescence microscopy fm staining in. Once stained as part of a sample, these organisms can resist the acid andor. Acid fastness is an uncommon characteristic shared by the genera mycobacterium and nocardia weakly acid fast. Acid fast bacterium an overview sciencedirect topics.
A counterstain of a contrasting color, such as methylene blue or brilliant green, is used to detect nonacidfast organisms in the smear, which do not retain the carbolfuchsin. In the ziehlneelsen stain, a fixed smear covered with carbolfuchsin is heated, rinsed, decolorized. Methods assessed include specimen collection, smear preparation, acid fast stain procedure, reading, and reporting. Acid alcohol can also be used as decolorizing solution, resistant organisms are referred to as acid fast bacilli afb or acid alcohol fast bacilli aafb. Positive acid fast stained smears with low numbers of organisms are not diagnostic, because of the presence of mycobacterium smegmatis in genital secretions of normal patients.
Mycobacterium tuberculosis part 4 afb stain acid fast. The afb stain test is often ordered to determine if you are currently infected with tuberculosis or nocardia. Furthermore, an acidfast stain can quickly assess patient infectiousness, and is also used to confirm that a culture is acid fast. Intheziehlneelsenmethod,thebasicfuchsinphenol dye is used hot, thus melting the waxy sub. The evaluator needs to have a good understanding of acidfast bacilli afb smear microscopy and good laboratory practice glp. Acid fast stains for mycobacteria prolab diagnostics.
Acid fast bacilli are stained with a primary stain that does not require heating and then with a decolorizing counter stain that does not require a separate acid or alcohol decolorization step. Ziehlneelsen zn method of acid fast staining technique is used to stain mycobacterium species including m. Acidfast bacillus afb stain kit is intended for laboratory use to identify, by light microscopy, acidfast bacilli, such as mycobacterium, in tissue samples. Acid fast bacilli afb smear and culture are two separate tests always performed together at the msphl, tuberculosis tb unit. Some of the groups of bacilli can be seen to have a limiting membrane. The stain binds to the mycolic acid in the mycobacterial cell wall. The evaluator must understand appropriate methods and ensure they are being followed.
The afb culture is the inoculation of a clinical specimen onto culture media bectondickinson mycobacteria growth. The next step is to decolorize all tissue components except the acid fast bacilli. It is believed that only leprosy bacilli which stain with carbolfuchsin as solid acidfast rods are viable and that bacilli which stain irregularly are probably dead and degenerating. Acid fast bacillus afb culture and afb stain arup test code 0060152 collected. The primary stain includes basic fuchsin, ethyl alcohol, isopropyl alcohol, phenol and water. Afb test also helps monitor the efficiency of treatment of these diseases. Tuberculosis, tb historically, major impact disease 100 yrs ago tb was biggest human killer many famous deaths believed to be genetic linked to genius. Dissolve 3g basic fuchsin in the mixture and add distilled water to bring.
Acid fastness is a physical property of certain bacteria and cellular structures. After staining, an acid decolorizing solution is applied. Currently, the diagnostic methods used are bacilloscopy and microbiological culture 9, but the main method for bacilli detection is the ziehlneelsen specific staining technique. Auramin staining, part of tb culture ziehlneelsen staining indication. Acid fast stain of gastric aspirate has a sensitivity of 30% and provides a useful clinical diagnosis if positive. Role of sputum examination for acid fast bacilli in. The presence of mycolic acid makes the bacteria very difficult to stain, but when heat or other agents are used to force carbolfuchsin into the cytoplasm, the bacteria resist decolorization with a dilute acid. General algorithm mgit 960 cultures 43 flow chart 2. Acidfast stain principle, procedure, interpretation and. Jun 12, 2018 the main aim of this staining is to differentiate bacteria into acid fast group and non acid fast groups. Afb stain or ziehlneelsen acid fast staining procedure. This removes the red dye from the background cells, tissue fibres, and any organisms in the smear except mycobacteria which retain hold fast to the dye and are therefore referred to as acid fast bacilli afb.
Acidfast bacilli definition of acidfast bacilli by the. Higher concentrations may kill or injure the acid fast bacteria 24% sodium hydroxide allows specimen to be exposed to decontamination for longer periods without affecting the recovery of acid fat bacilli. Acidfast bacilli are stained with a primary stain that does not require heating and then with a decolorizing counterstain that does not require a separate acid or alcohol decolorization step. Nonacidfast bacteria stain green or blue, depending on the counterstain used. The main aim of this staining is to differentiate bacteria into acid fast group and non acid fast groups. The term acidfast bacilli is practically synonymous with mycobacteria, although nocardia and some other organisms are variably acid fast. Avoid overstaining as some weak staining bacterial staining can be replaced by methylene blue.
Used in the demonstration of acidfast bacteria belonging to the genus. The lipoid capsule of the acid fast organism takes up carbol fuchsin and resists decolorization. We compared the sensitivity and specificity of a modified ziehlneelsen modifiedzn staining method for acidfast bacilli afb with that of the standard ziehlneelsen standardzn staining method, using culture results with mycobacterium tuberculosis as the gold standard. Differentiate with reagent 2 until the red blood corpuscles retain the stain when examined under the microscope. Identify the presence of acid fast bacilli in tissue sections and to produce optimal staining while reducing precipitate with the thermo scientific richardallan scientific acid fast bacillus blue and green secondary stains. Positive acidfast stained smears with low numbers of organisms are not diagnostic, because of the presence of mycobacterium smegmatis in genital secretions of normal patients. Identify the presence of acidfast bacilli in tissue sections and to produce optimal staining while reducing precipitate with the thermo scientific richardallan scientific acid fast bacillus blue and green secondary stains. The term acid fast bacilli is practically synonymous with mycobacteria, although nocardia and some other organisms are variably acid fast.
Use millipore filtered water in the waterbath and staining procedure. The main aim of this staining is to differentiate bacteria into acid fast group and nonacid fast groups. Differentiation between mycobacteria species is typically made in positive cultures based on phenotypic and biochemical traits. The evaluator needs to have a good understanding of acid fast bacilli afb smear microscopy and good laboratory practice glp. Mycobacteria possess unique acid fast characteristics that make the acid fast staining techniques valuable for detecting tubercle bacilli.
The lipid content of the cell wall of acid fast bacilli makes staining of the organisms difficult. Flood the slide with reagent 11 ml heat by flaming until stain rises and reheat at intervals. Afb stain urine test test results, normal range, cost and. Mycobacteria are called acid fast bacilli because they are a group of rodshaped bacteria bacilli that can be seen under the microscope following a staining procedure where the bacteria retain the color of the stain after an acid wash acid fast. Acid fast bacilli red leprae bacilli are short rods nocardia red nocardia organisms are long, thin, and filamentous erythrocytes pale pink. Acidfast bacilli synonyms, acidfast bacilli pronunciation, acidfast bacilli translation, english dictionary definition of acidfast bacilli. Staining techniques for detection of acid fast bacilli herbert. In the ziehlneelsen stain, a fixed smear covered with carbolfuchsin is heated, rinsed, decolorized with acid alcohol, and counterstained with methylene blue.
Acidfast bacilli afb smear and culture state public. Currently in most laboratories, methods of staining using fluorescence microscopy fm and lightemitting diodes led microscopy for acid fast bacilli afb are. Used in the demonstration of acidfast bacteria belonging to the genus mycobacterium, which include the causative agent for tuberculosis. Pdf staining techniques for detection of acid fast bacilli. Preparation and examination of skin smears official web. The mycobacteria include species in the genus mycobacterium. The acidfast bacilli test or afb test thus tests the existence of bacterial infection in the body by collecting samples from blood, urine, stool, phlegm, etc. Acidfast stain of gastric aspirate has a sensitivity of 30% and provides a useful clinical diagnosis if positive. An acidfast bacilli afb culture test detects afb that retain the colour of a stain after an acid wash. The ziehlneelsen method is probably the best known and most frequently used procedure for staining tubercle bacilli. Diseases caused by acidfast organisms, mycobacterium, et al. Acidfast bacillus afb stain kit english code ar162 intended use for in vitro diagnostic use. Additional charge for concentration cpt 87015 and stain cpt 87206.
The presence of acid fast bacilli in multiple specimens was investigated comparatively with ziehl. Methods assessed include specimen collection, smear preparation, acidfast stain procedure, reading, and reporting. Afb test acid fast bacilli test about, preparation, test. The lipoid capsule of the acidfast organism takes up carbol fuchsin and resists decolorization. Acid fastness is a physical property of certain bacterial and eukaryotic cells, as well as some subcellular structures, specifically their resistance to decolorization by acids during laboratory staining procedures. The lipoid capsule of the acidfast organism takes up carbolfuchsin and resists decolorization with a dilute acid rinse. The detection limit of an acidfast stain has been estimated to be 500010 000 bacilliml of sputum.
A note to file ntf is a document used to describe an error i. Pages in category acid fast bacilli the following 115 pages are in this category, out of 115 total. Printerfriendly preparation and examination of skin smears pdf 225 kb. Afb stain or ziehlneelsen acidfast staining procedure. Explain the purpose and significance of acid fast bacilli afb. Acidfast bacillus afb culture and afb stain arup test code 0060152 collected. Your doctor can order this test to find out if you have tuberculosis tb or another type of bacterial. Mixed nodular and fibrotic lesions may contain slowly multiplying tubercle bacilli and have the potential for progression to tb disease. This method is used for those microorganisms which are not staining by simple or gram staining method, particularly the member of genus mycobacterium, are resistant and can only be visualized by acidfast staining.
Revised july 2019 carbol fuchsin stain, ziehlneelsen for afb. Carbol fuchsin stain, ziehlneelsen, combines phenol and basic fuchsin that works to permeate the lipoid capsule of acid fast organisms and renders them resistant to acid alcohol decolorization. Secondly it identifies acid fast bacilli using zielhneelson. However, in developing countries, such as india, where most laboratories rely. A comparative study on the different staining methods. Carbolfuchsin solution, microwave 80 power, 45 seconds, allow slides to stand in hot solution for 5 minutes. In acid fast stains, the phenol allows the stain to pen etrate, even after. Artisan acidfast bacillus afb stain kit english code. Acid fast staining in formalinfixed tissue specimen of. Because of this feature, this stain is extremely helpful in identification in diseases caused by acid fast bacteria, particularly tuberculosis and leprosy.
Sputum for acid fast bacilli afb is seldom looked for in the etiological diagnosis of tuberculous pleural effusion usually due to the absence of any parenchymal lesion radiologically, but presence of tubercle bacilli in sputum may have important epidemiological and therapeutic implication. Acidfast stain principle, procedure, interpretation and examples. Persons who have lesions consistent with findings of old. In addition, the stain is used to determine the presence of af bacteria from. The skin smear is a valuable, costeffective tool in the routine management of the patient with hansens disease. An acid fast stain is a laboratory test performed on a sample of. The method requires controlled heating for its success. Jan 11, 2020 acid alcohol can also be used as decolorizing solution, resistant organisms are referred to as acid fast bacilli afb or acid alcohol fast bacilli aafb.
157 258 164 1257 1225 814 417 202 79 851 779 1436 959 326 14 34 1096 375 1156 679 594 719 1442 99 733 1006 896 1283 345 431 282 1281 519 707 1184 464 970 323 887 1103 738 975 87 1043 54