This document discusses serology, which is the study of immune reactions in blood. The key concepts covered are:
- Serology examines the antibody-antigen reaction, where antigens provoke the production of antibodies that fight invading organisms.
- Samples are analyzed using techniques like agglutination, precipitation, and fluorescent antibodies to detect antigens or antibodies.
- Abnormal results can indicate current or past infections, or immunity.
Specific applications of serology discussed include tests for syphilis, typhoid, hepatitis, HIV, and pregnancy. Serology is used to diagnose infectious diseases by detecting pathogens, their products, or immune responses in serum.
CRP is an acute-phase protein of hepatic origin that increases following interleukin-6 secretion by macrophages and T cells.
Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation of the joints.
Antibodies directed against the Fc fragment of immunoglobulin G (IgG) are called rheumatoid factors (RFs). They are heterogenous and usually composed of immunoglobulin M (IgM)
The RPR test is a screening test for syphilis that detects nonspecific antilipid antibodies produced in response to infection with Treponema pallidum, the bacterium that causes syphilis. It is a qualitative slide agglutination test where carbon particles coated with lipids are agglutinated by reagin antibodies in the serum sample, making the charcoal clump visibly. A reactive result indicates the presence of reagin and potential syphilis infection, while a non-reactive result means no reagin was detected. Only serum or plasma samples should be used to avoid interference.
The document discusses evaluating the efficacy of the OraQuick rapid HIV test kit using oral fluid for HIV antibody detection in patients attending dental hospitals in India. The study found the OraQuick test to have a sensitivity and specificity of 100% compared to standard blood tests. It was found to be an effective and accurate screening tool for HIV detection using oral fluid. However, it could not distinguish between HIV-1 and HIV-2 antibodies. Further larger studies were recommended to introduce it as a routine screening procedure.
The document summarizes laboratory tests for diagnosing HIV infection. It describes the structure of the HIV virus and how it infects CD4+ T-cells. The main purposes of HIV testing are to prevent transmission through blood or from mother to child. HIV diagnosis involves screening assays like ELISA and rapid tests, followed by confirmatory tests like Western blot. Viral load and CD4 count are used to monitor disease progression. New techniques allow detection of HIV in alternative specimens like saliva, urine and oral fluids. Diagnosis in infants is challenging due to passive antibody transfer.
Serology is the study of blood serum and the detection of antibodies and antigens. Key events in the history of serology include Karl Landsteiner's 1901 discovery of the A, B, and O blood groups. Serological tests can be classified as primary, secondary, or tertiary based on their level of sensitivity and directness of measurement. Common serological techniques include ELISA, immunofluorescence, agglutination tests, precipitation reactions, and complement fixation tests. These methods are used to detect infections and other medical conditions.
A sincere effort
A compilation of all the diagnostic methods for diagnosis of ToRCH gp of infections in Pregnant women..
Presentation is done in two parts-
part-1 includes Toxoplasmosis and Rubella virus infection
Part-2- Cytomegalovirus, HSV-1, HSV-2 are covered
microbiological, lab diagnosis of Torch complex, Laboratory diagnosis of TORCH complex, Cytomegalovirus, Herpes simplex type1, HSV-1, Herpes simplex type2, HSV-2,
Shell vial technique,
The Coombs test, also known as the direct antiglobulin test (DAT) or indirect antiglobulin test (IAT), detects antibodies or complement coating red blood cells. It involves sensitizing RBCs with patient serum, washing unbound antibodies, then adding anti-human globulin reagent to form a "bridge" and cause agglutination if antibodies or complement are present on the RBCs. Controls like Coombs control check cells are used to validate negative results and detect technical problems. The DAT detects in vivo coating while the IAT detects in vitro coating during antibody screening and identification.
CRP is an acute-phase protein of hepatic origin that increases following interleukin-6 secretion by macrophages and T cells.
Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation of the joints.
Antibodies directed against the Fc fragment of immunoglobulin G (IgG) are called rheumatoid factors (RFs). They are heterogenous and usually composed of immunoglobulin M (IgM)
The RPR test is a screening test for syphilis that detects nonspecific antilipid antibodies produced in response to infection with Treponema pallidum, the bacterium that causes syphilis. It is a qualitative slide agglutination test where carbon particles coated with lipids are agglutinated by reagin antibodies in the serum sample, making the charcoal clump visibly. A reactive result indicates the presence of reagin and potential syphilis infection, while a non-reactive result means no reagin was detected. Only serum or plasma samples should be used to avoid interference.
The document discusses evaluating the efficacy of the OraQuick rapid HIV test kit using oral fluid for HIV antibody detection in patients attending dental hospitals in India. The study found the OraQuick test to have a sensitivity and specificity of 100% compared to standard blood tests. It was found to be an effective and accurate screening tool for HIV detection using oral fluid. However, it could not distinguish between HIV-1 and HIV-2 antibodies. Further larger studies were recommended to introduce it as a routine screening procedure.
The document summarizes laboratory tests for diagnosing HIV infection. It describes the structure of the HIV virus and how it infects CD4+ T-cells. The main purposes of HIV testing are to prevent transmission through blood or from mother to child. HIV diagnosis involves screening assays like ELISA and rapid tests, followed by confirmatory tests like Western blot. Viral load and CD4 count are used to monitor disease progression. New techniques allow detection of HIV in alternative specimens like saliva, urine and oral fluids. Diagnosis in infants is challenging due to passive antibody transfer.
Serology is the study of blood serum and the detection of antibodies and antigens. Key events in the history of serology include Karl Landsteiner's 1901 discovery of the A, B, and O blood groups. Serological tests can be classified as primary, secondary, or tertiary based on their level of sensitivity and directness of measurement. Common serological techniques include ELISA, immunofluorescence, agglutination tests, precipitation reactions, and complement fixation tests. These methods are used to detect infections and other medical conditions.
A sincere effort
A compilation of all the diagnostic methods for diagnosis of ToRCH gp of infections in Pregnant women..
Presentation is done in two parts-
part-1 includes Toxoplasmosis and Rubella virus infection
Part-2- Cytomegalovirus, HSV-1, HSV-2 are covered
microbiological, lab diagnosis of Torch complex, Laboratory diagnosis of TORCH complex, Cytomegalovirus, Herpes simplex type1, HSV-1, Herpes simplex type2, HSV-2,
Shell vial technique,
The Coombs test, also known as the direct antiglobulin test (DAT) or indirect antiglobulin test (IAT), detects antibodies or complement coating red blood cells. It involves sensitizing RBCs with patient serum, washing unbound antibodies, then adding anti-human globulin reagent to form a "bridge" and cause agglutination if antibodies or complement are present on the RBCs. Controls like Coombs control check cells are used to validate negative results and detect technical problems. The DAT detects in vivo coating while the IAT detects in vitro coating during antibody screening and identification.
C-reactive protein (CRP) is a marker for inflammation that is produced by the liver and measured via a blood test. CRP levels rise in response to inflammation and can help diagnose bacterial infections. A rapid latex agglutination test is commonly used to measure CRP levels qualitatively, involving mixing patient serum with antibody-coated latex particles. If CRP is present, the particles will agglutinate, indicating a positive result. Precise reaction timing and controls are needed to get an accurate reading.
The Widal test detects antibodies in patient serum that agglutinate Salmonella typhi and paratyphi antigens. It was developed in 1896 by Georges Widal and is useful for diagnosing typhoid fever in endemic areas without culture facilities. The test involves mixing patient serum with O and H antigens of S. typhi and S. paratyphi and observing for agglutination, which indicates the presence of antibodies. A rising titre in sequential samples supports a diagnosis of typhoid fever.
The document discusses the Coombs test, which involves using Coombs serum (anti-human globulin) to detect sensitization of red blood cells. It describes the principles and procedures for both the direct and indirect Coombs test. The direct Coombs test detects antibodies or complement attached to red blood cells in vivo, while the indirect Coombs test detects circulating antibodies in the blood capable of attaching to red blood cells. The document provides detailed steps for performing both tests, and discusses interpretations and potential sources of false positive results.
casoni test is an immediate hypersensitivity skin test previously used in the diagnosis of hydatid disease.
Intradermal injection of 0.2ml of hydatid fluid collected from animal/human cyst which is sterilized by seitz filtration OR membrane filtration.
equal volume of saline(control) injected on the other forearm and observation made for next 30 min and after 1 to 2 days.
As a precaution anaphylactic tray must be kept ready before carrying out the test.(Type 1 hypersensitivity reaction)
Interpretation: Sensitive patients develop large wheal measuring 5 cm or more with formation of pseudopodia like projection within 30 minutes occuring at injection site, considered positive result.(immediate hypersensitivity) .
No reaction in the control arm.
Disadvantage: It has low sensitivity (60-80%)
and gives false positive results in cross reactive cestode infections.
It is no longer used nowadays and replaced largely by the serological tests.
Less reliable than imaging technique.
This document discusses laboratory diagnosis of HIV infection. It describes the types of tests used, including screening tests like ELISA that detect antibodies or antigens, and confirmatory tests like Western blot that detect antibodies to specific HIV proteins. Screening tests are used initially while confirmatory tests are needed to definitively diagnose HIV infection. Factors that can lead to false positive, false negative, or indeterminate results on HIV tests are also reviewed.
The document describes a rapid test strip method for detecting hepatitis B surface antigen (HBsAg) in serum or plasma. Hepatitis B virus (HBV) is a major cause of liver disease and cancer worldwide. The test works by detecting HBsAg, which appears early in hepatitis B infection, on a strip using monoclonal antibodies and colloidal gold. To use the test, serum is placed on the strip and results are read after 15 minutes, with lines at the test and control regions indicating a positive result. The test is designed to quickly detect HBsAg qualitatively but has limitations if antigen levels are low or interfering substances are present.
Widal test is a blood test for detecting Enteric fever (Typhoid fever and Paratyphoid fever). Enteric fever is a systemic infection caused by bacteria, usually through ingestion of contaminated food or water.
Reference: https://www.1mglabs.com/test/widal-test-1970
https://www.1mglabs.com/test/widal-test-1979
The document discusses different types of blood samples and liver function tests. It explains that plasma contains clotting factors while serum does not. Several liver function tests are described including ALT, AST, ALP, GGT, total protein, albumin, and bilirubin. The roles and clinical significance of these enzymes and proteins are summarized. Kidney function tests and lipid and blood glucose tests are also briefly mentioned.
This document discusses Streptolysin O, an exotoxin produced by Streptococcus pyogenes bacteria, and the Antistreptolysin O (ASO) antibody produced in response. It describes how the ASO latex agglutination test is used to detect ASO antibodies as a way to diagnose post-streptococcal conditions like rheumatic fever when live bacteria cannot be cultured. The test works by detecting if patient serum causes agglutination of latex particles coated with Streptolysin O antigen, indicating the presence of ASO antibodies. The procedure, interpretation of positive and negative results, and limitations are provided.
The document provides details about stool examination. It discusses the advantages of stool examination in investigating GIT diseases such as detection of parasites, evaluation of diarrhea, dysentery, and identification of causative bacteria. It describes the collection and macroscopic examination of stool samples and preparation of slides. The concentration techniques help detect small numbers of parasites. Microscopic examination identifies features like leukocytes, red blood cells, parasites, and indicates conditions like malabsorption. Overall, stool examination is a useful diagnostic tool for gastrointestinal diseases.
This document provides information about enteric fever (typhoid fever) in 43 sections. It discusses the history, causative agents, transmission, signs and symptoms, diagnosis, treatment and prevention. Regarding diagnosis, it describes tests such as blood, stool and urine cultures, the Widal test and slide agglutination. Salmonella typhi and paratyphi cause typhoid and paratyphoid fever respectively by ingesting contaminated food or water. Complications can include sepsis and meningitis. Antibiotics are used for treatment, but drug resistance has emerged. Vaccines provide protection against the disease.
The document discusses reference ranges and normal ranges. It defines reference ranges as the limits of results expected for a given condition based on measurements from a reference population. Reference ranges include 95% of values from healthy individuals and are used to interpret patient test results. Normal ranges refer specifically to the central 95% of values from a healthy population, forming a symmetric distribution. Reference ranges can be affected by factors like age, sex, pregnancy, and time of day. They are used for diagnosing diseases, monitoring physiological conditions, and guiding therapeutic treatment.
This document discusses the laboratory investigation of transfusion reactions. It begins by defining transfusion and transfusion reactions. It then outlines the initial measures taken before investigation, including maintaining IV saline and notifying physicians. The main laboratory investigations include clerical checks to identify errors, visual checks of plasma for hemolysis, and serology checks including ABO testing and direct antiglobulin testing on pre-and post-transfusion samples. If these preliminary tests have positive results, additional tests like grouping, antibody screening and crossmatching are repeated from before transfusion.
Dengue is a rapidly spreading mosquito-borne viral disease. During the acute phase of infection, up to 5 days after onset of symptoms, the dengue virus can be detected through NS1 antigen detection, virus isolation, or nucleic acid detection. From 3 days to 2 months after symptoms begin, dengue-specific IgM antibodies are detectable and used for diagnosis. IgG antibodies develop later, after 3 weeks, and can be detected for months or life, indicating a past infection. Differentiating primary from secondary dengue infection involves measuring the ratio of IgM to IgG antibodies. Monitoring of platelet counts and hematocrit values during the acute phase aids diagnosis and assessment of severity.
The Coombs test, also known as the antiglobulin test, detects antibodies or complement proteins attached to red blood cells. There are two types of Coombs tests - the direct Coombs test detects antibodies bound to red blood cells in vivo, while the indirect Coombs test detects antibodies in a patient's serum that can bind to red blood cells in vitro. The Coombs test is used to diagnose conditions like hemolytic disease of the newborn, autoimmune hemolytic anemia, and hemolytic transfusion reactions. A positive Coombs test indicates red blood cell sensitization, while a negative test suggests the absence of sensitization.
1. Urinary tract infections (UTIs) are caused by microbial invasion of the urinary tract from the kidneys to the urethra. E. coli is the most common causative organism, followed by other gram-negative bacilli and some gram-positive organisms.
2. Laboratory diagnosis of UTIs involves urine microscopy to identify white and red blood cells and bacteria, culture to isolate and quantify bacterial growth, and antibiotic susceptibility testing to determine the most effective antibiotic treatment.
3. A significant bacterial count of ≥105 CFU/ml indicates an active UTI, while lower counts may be considered contaminated. Identification of bacterial isolates is done through colony characteristics, gram stain, and biochemical tests
MRSA is a type of staph bacteria that is resistant to certain antibiotics such as methicillin and penicillin. It can cause infections of the skin or other parts of the body. MRSA was first identified in the 1960s and has since emerged in both healthcare and community settings. Risk factors for MRSA infection include prior MRSA infection or colonization, exposure to healthcare settings, and underlying medical conditions. Laboratories test for MRSA resistance using methods such as cefoxitin disk screening and PCR detection of the mecA gene. Proper hand hygiene and infection control practices can help reduce the spread of MRSA.
This document discusses methods for detecting Methicillin-Resistant Staphylococcus aureus (MRSA). MRSA is any strain of S. aureus that is resistant to beta-lactam antibiotics due to the mecA gene. Rapid detection of MRSA is important for optimal treatment and reducing costs. The document describes several screening methods, focusing on the oxacillin salt agar screening test which involves growing bacterial samples on agar containing oxacillin and 4% NaCl. Growth of more than one colony indicates oxacillin resistance and identifies the strain as MRSA.
The lecture was presented to the students of Saudi board of Community Medicine to help them know about the various serological methods applicable in the diagnosis of infectious diseases in general with attention upon the specificity and sensitivity of various diagnostic modalities. The lecture covers the basic principles of each test and the clinical applications with the advantages and disadvantages of each.
Antigen ,Antibody and Ag-Ab reactions ppt by DR.C.P.PRINCEDR.PRINCE C P
An immunogen refers to a molecule that is capable of eliciting an immune response, whereas an antigen refers to a molecule that is capable of binding to the product of that immune response (Ab).
So, an immunogen is necessarily an antigen, but an antigen may not necessarily be an immunogen
The terms immunogen and antigen are often used interchangeably but the later is more common.
Antibodies are Globulin Protein (Immunoglobulin) that are synthesized in the Serum and Tissue fluids.
It reacts specifically with the antigen that stimulated their production.
There are two types serum proteins: albumin and globulin
There are Three types of globulins .
1. Alpha globulin
2. Beta globulin
3. Gamma globulin (Antibodies)
Gamma globulins are responsible for immunity. So they are called as Immunoglobulin (Ig)
The binding of an antibody with an antigen of the type that stimulated the formation of antibody that results in the following reaction
Agglutination
Precipitation
Complement fixation
Phagocytosis
Neutralization of an exotoxin
Opsonization
Tissue fixation
Chemotaxis
Activation of mast cells and basophils
PPT prepared by:
DR.PRINCE C P
Associate Professor , Department of Microbiology,
Mother Theresa Post Graduate & Research Institute of Health Sciences (Government of Puducherry Institution)
C-reactive protein (CRP) is a marker for inflammation that is produced by the liver and measured via a blood test. CRP levels rise in response to inflammation and can help diagnose bacterial infections. A rapid latex agglutination test is commonly used to measure CRP levels qualitatively, involving mixing patient serum with antibody-coated latex particles. If CRP is present, the particles will agglutinate, indicating a positive result. Precise reaction timing and controls are needed to get an accurate reading.
The Widal test detects antibodies in patient serum that agglutinate Salmonella typhi and paratyphi antigens. It was developed in 1896 by Georges Widal and is useful for diagnosing typhoid fever in endemic areas without culture facilities. The test involves mixing patient serum with O and H antigens of S. typhi and S. paratyphi and observing for agglutination, which indicates the presence of antibodies. A rising titre in sequential samples supports a diagnosis of typhoid fever.
The document discusses the Coombs test, which involves using Coombs serum (anti-human globulin) to detect sensitization of red blood cells. It describes the principles and procedures for both the direct and indirect Coombs test. The direct Coombs test detects antibodies or complement attached to red blood cells in vivo, while the indirect Coombs test detects circulating antibodies in the blood capable of attaching to red blood cells. The document provides detailed steps for performing both tests, and discusses interpretations and potential sources of false positive results.
casoni test is an immediate hypersensitivity skin test previously used in the diagnosis of hydatid disease.
Intradermal injection of 0.2ml of hydatid fluid collected from animal/human cyst which is sterilized by seitz filtration OR membrane filtration.
equal volume of saline(control) injected on the other forearm and observation made for next 30 min and after 1 to 2 days.
As a precaution anaphylactic tray must be kept ready before carrying out the test.(Type 1 hypersensitivity reaction)
Interpretation: Sensitive patients develop large wheal measuring 5 cm or more with formation of pseudopodia like projection within 30 minutes occuring at injection site, considered positive result.(immediate hypersensitivity) .
No reaction in the control arm.
Disadvantage: It has low sensitivity (60-80%)
and gives false positive results in cross reactive cestode infections.
It is no longer used nowadays and replaced largely by the serological tests.
Less reliable than imaging technique.
This document discusses laboratory diagnosis of HIV infection. It describes the types of tests used, including screening tests like ELISA that detect antibodies or antigens, and confirmatory tests like Western blot that detect antibodies to specific HIV proteins. Screening tests are used initially while confirmatory tests are needed to definitively diagnose HIV infection. Factors that can lead to false positive, false negative, or indeterminate results on HIV tests are also reviewed.
The document describes a rapid test strip method for detecting hepatitis B surface antigen (HBsAg) in serum or plasma. Hepatitis B virus (HBV) is a major cause of liver disease and cancer worldwide. The test works by detecting HBsAg, which appears early in hepatitis B infection, on a strip using monoclonal antibodies and colloidal gold. To use the test, serum is placed on the strip and results are read after 15 minutes, with lines at the test and control regions indicating a positive result. The test is designed to quickly detect HBsAg qualitatively but has limitations if antigen levels are low or interfering substances are present.
Widal test is a blood test for detecting Enteric fever (Typhoid fever and Paratyphoid fever). Enteric fever is a systemic infection caused by bacteria, usually through ingestion of contaminated food or water.
Reference: https://www.1mglabs.com/test/widal-test-1970
https://www.1mglabs.com/test/widal-test-1979
The document discusses different types of blood samples and liver function tests. It explains that plasma contains clotting factors while serum does not. Several liver function tests are described including ALT, AST, ALP, GGT, total protein, albumin, and bilirubin. The roles and clinical significance of these enzymes and proteins are summarized. Kidney function tests and lipid and blood glucose tests are also briefly mentioned.
This document discusses Streptolysin O, an exotoxin produced by Streptococcus pyogenes bacteria, and the Antistreptolysin O (ASO) antibody produced in response. It describes how the ASO latex agglutination test is used to detect ASO antibodies as a way to diagnose post-streptococcal conditions like rheumatic fever when live bacteria cannot be cultured. The test works by detecting if patient serum causes agglutination of latex particles coated with Streptolysin O antigen, indicating the presence of ASO antibodies. The procedure, interpretation of positive and negative results, and limitations are provided.
The document provides details about stool examination. It discusses the advantages of stool examination in investigating GIT diseases such as detection of parasites, evaluation of diarrhea, dysentery, and identification of causative bacteria. It describes the collection and macroscopic examination of stool samples and preparation of slides. The concentration techniques help detect small numbers of parasites. Microscopic examination identifies features like leukocytes, red blood cells, parasites, and indicates conditions like malabsorption. Overall, stool examination is a useful diagnostic tool for gastrointestinal diseases.
This document provides information about enteric fever (typhoid fever) in 43 sections. It discusses the history, causative agents, transmission, signs and symptoms, diagnosis, treatment and prevention. Regarding diagnosis, it describes tests such as blood, stool and urine cultures, the Widal test and slide agglutination. Salmonella typhi and paratyphi cause typhoid and paratyphoid fever respectively by ingesting contaminated food or water. Complications can include sepsis and meningitis. Antibiotics are used for treatment, but drug resistance has emerged. Vaccines provide protection against the disease.
The document discusses reference ranges and normal ranges. It defines reference ranges as the limits of results expected for a given condition based on measurements from a reference population. Reference ranges include 95% of values from healthy individuals and are used to interpret patient test results. Normal ranges refer specifically to the central 95% of values from a healthy population, forming a symmetric distribution. Reference ranges can be affected by factors like age, sex, pregnancy, and time of day. They are used for diagnosing diseases, monitoring physiological conditions, and guiding therapeutic treatment.
This document discusses the laboratory investigation of transfusion reactions. It begins by defining transfusion and transfusion reactions. It then outlines the initial measures taken before investigation, including maintaining IV saline and notifying physicians. The main laboratory investigations include clerical checks to identify errors, visual checks of plasma for hemolysis, and serology checks including ABO testing and direct antiglobulin testing on pre-and post-transfusion samples. If these preliminary tests have positive results, additional tests like grouping, antibody screening and crossmatching are repeated from before transfusion.
Dengue is a rapidly spreading mosquito-borne viral disease. During the acute phase of infection, up to 5 days after onset of symptoms, the dengue virus can be detected through NS1 antigen detection, virus isolation, or nucleic acid detection. From 3 days to 2 months after symptoms begin, dengue-specific IgM antibodies are detectable and used for diagnosis. IgG antibodies develop later, after 3 weeks, and can be detected for months or life, indicating a past infection. Differentiating primary from secondary dengue infection involves measuring the ratio of IgM to IgG antibodies. Monitoring of platelet counts and hematocrit values during the acute phase aids diagnosis and assessment of severity.
The Coombs test, also known as the antiglobulin test, detects antibodies or complement proteins attached to red blood cells. There are two types of Coombs tests - the direct Coombs test detects antibodies bound to red blood cells in vivo, while the indirect Coombs test detects antibodies in a patient's serum that can bind to red blood cells in vitro. The Coombs test is used to diagnose conditions like hemolytic disease of the newborn, autoimmune hemolytic anemia, and hemolytic transfusion reactions. A positive Coombs test indicates red blood cell sensitization, while a negative test suggests the absence of sensitization.
1. Urinary tract infections (UTIs) are caused by microbial invasion of the urinary tract from the kidneys to the urethra. E. coli is the most common causative organism, followed by other gram-negative bacilli and some gram-positive organisms.
2. Laboratory diagnosis of UTIs involves urine microscopy to identify white and red blood cells and bacteria, culture to isolate and quantify bacterial growth, and antibiotic susceptibility testing to determine the most effective antibiotic treatment.
3. A significant bacterial count of ≥105 CFU/ml indicates an active UTI, while lower counts may be considered contaminated. Identification of bacterial isolates is done through colony characteristics, gram stain, and biochemical tests
MRSA is a type of staph bacteria that is resistant to certain antibiotics such as methicillin and penicillin. It can cause infections of the skin or other parts of the body. MRSA was first identified in the 1960s and has since emerged in both healthcare and community settings. Risk factors for MRSA infection include prior MRSA infection or colonization, exposure to healthcare settings, and underlying medical conditions. Laboratories test for MRSA resistance using methods such as cefoxitin disk screening and PCR detection of the mecA gene. Proper hand hygiene and infection control practices can help reduce the spread of MRSA.
This document discusses methods for detecting Methicillin-Resistant Staphylococcus aureus (MRSA). MRSA is any strain of S. aureus that is resistant to beta-lactam antibiotics due to the mecA gene. Rapid detection of MRSA is important for optimal treatment and reducing costs. The document describes several screening methods, focusing on the oxacillin salt agar screening test which involves growing bacterial samples on agar containing oxacillin and 4% NaCl. Growth of more than one colony indicates oxacillin resistance and identifies the strain as MRSA.
The lecture was presented to the students of Saudi board of Community Medicine to help them know about the various serological methods applicable in the diagnosis of infectious diseases in general with attention upon the specificity and sensitivity of various diagnostic modalities. The lecture covers the basic principles of each test and the clinical applications with the advantages and disadvantages of each.
Antigen ,Antibody and Ag-Ab reactions ppt by DR.C.P.PRINCEDR.PRINCE C P
An immunogen refers to a molecule that is capable of eliciting an immune response, whereas an antigen refers to a molecule that is capable of binding to the product of that immune response (Ab).
So, an immunogen is necessarily an antigen, but an antigen may not necessarily be an immunogen
The terms immunogen and antigen are often used interchangeably but the later is more common.
Antibodies are Globulin Protein (Immunoglobulin) that are synthesized in the Serum and Tissue fluids.
It reacts specifically with the antigen that stimulated their production.
There are two types serum proteins: albumin and globulin
There are Three types of globulins .
1. Alpha globulin
2. Beta globulin
3. Gamma globulin (Antibodies)
Gamma globulins are responsible for immunity. So they are called as Immunoglobulin (Ig)
The binding of an antibody with an antigen of the type that stimulated the formation of antibody that results in the following reaction
Agglutination
Precipitation
Complement fixation
Phagocytosis
Neutralization of an exotoxin
Opsonization
Tissue fixation
Chemotaxis
Activation of mast cells and basophils
PPT prepared by:
DR.PRINCE C P
Associate Professor , Department of Microbiology,
Mother Theresa Post Graduate & Research Institute of Health Sciences (Government of Puducherry Institution)
Serological techniques and immune assayseman youssif
This document discusses various serological and immune assay techniques. It begins by defining serological assays and immune assays. It then describes different types of serological reactions including agglutination (direct, indirect, conglutination, latex agglutination) and precipitation (ring precipitation test, slide precipitation, gel diffusion precipitation, immunoelectrophoresis, countercurrent immunoelectrophoresis). The document also discusses immune assays including principles, qualitative vs quantitative assays, and different methods like immunoprecipitation, particle immunoassays, immunonephelometry, radioimmunoassay, enzyme immunoassay, fluorescent immunoassay, and chemiluminescent immunoassay. It provides examples of using these techniques to detect antigens and antibodies.
This document describes various methods for detecting antigen-antibody reactions, including primary reactions like precipitation and agglutination that are visible to the naked eye, as well as secondary reactions that require labels like enzymes, radioisotopes, or fluorescent substances and can be seen using techniques like immunofluorescence (IF), enzyme-linked immunosorbent assay (ELISA), radioimmunoassay (RIA), Western blotting, and flow cytometry. It provides details on the principles, procedures, applications, and examples of each method.
This document describes various serological tests used to detect antigens and antibodies. It discusses primary tests like ELISA, IFAT, and RIA. Secondary tests include agglutination, complement fixation, precipitation, and neutralization tests. Tertiary tests determine antibody protective value. Agglutination tests can qualitatively and quantitatively detect particulate antigens. Coombs tests detect non-agglutinating antibodies. ELISA is then explained in detail, including indirect, sandwich, and competitive formats. ELISA is widely used to detect antigens and antibodies in applications like HIV and food allergen testing.
The complement system helps antibodies and phagocytes clear pathogens. It consists of liver-produced proteins in blood. The complement fixation test detects antibodies or antigens using this system. It was used for infections like rickettsiosis. There are two steps - complement is fixed to antigen-antibody complexes in the first step, then remaining complement is detected using sheep blood cells in the second step. Anti-streptolysin O antibodies are detected using a similar process to detect streptococcal infections.
The document describes the complement fixation test (CFT), a serological test used to detect antibodies. It involves two steps - in the first step, complement is fixed to an antigen-antibody complex. In the second step, free complement is detected using a hemolytic system containing sheep red blood cells, which will cause lysis in the absence of fixed complement, indicating a negative test result. The CFT requires five reagents - antigen, antibody, complement, red blood cells, and amboceptor antibody against red blood cells. A positive test shows no lysis, while a negative test shows lysis.
This document discusses immunity and antigen-antibody reactions. It begins with definitions of immunity, antigens, and antibodies. It describes the components of the immune system including antigen specificity and types of antigens. It then explains antigen-antibody reactions and how they are used for diagnostic tests. Different diagnostic tests are also summarized, including precipitation reactions, agglutination, immunofluorescence, radioimmunoassay, and ELISA. Potential sources of markers for periodontal disease activity are also listed.
The document discusses typhoid fever and methods for diagnosing the disease. It begins by describing the causative bacteria, Salmonella Typhi, and how it is transmitted. It then discusses several diagnostic tests including the Widal test, which detects antibodies in serum and was the first test developed for typhoid. The document provides details on performing and interpreting the Widal test as well as its limitations. Finally, it summarizes several other diagnostic tests for typhoid fever such as the Tubex test, dipstick assay, and Typhidot assay, which aim to improve on the Widal test by providing faster, easier results.
Pretransfusion testing final- ab screening - NAGLAA MAKRAM Naglaa Makram
1. Antibody screening tests patient serum against reagent red blood cells to detect unexpected antibodies that could destroy transfused donor cells.
2. Screening cells must contain many common antigens and include some cells with homozygous antigen expression to detect weakly reacting antibodies.
3. A positive antibody screen requires antibody identification testing to determine the antibody specificity so that antigen-negative blood can be transfused.
This document discusses various laboratory diagnosis methods for infectious diseases, including both conventional and modern techniques. [1] Microscopic examination, culture isolation, and serological/immunological identification were described as conventional methods. [2] Limitations of conventional methods led to development of molecular biology techniques like PCR, DNA probes, and microarray technology which provide early and sensitive diagnosis. [3] Specific techniques like ELISA, RIA, immunoblotting, and nucleic acid-based methods like PCR, RFLP, and microarray analysis are now commonly used for laboratory diagnosis of infectious diseases.
This document provides information about enteric fever caused by Salmonella Typhi and Paratyphi. It discusses the classification, antigenic structure, pathogenesis and clinical manifestations of typhoidal Salmonella. It also covers the laboratory diagnosis of enteric fever including culture-based and serological tests. Important points include that S. Typhi causes typhoid fever while S. Paratyphi causes paratyphoid fever. Diagnosis involves blood and stool culture as well as the Widal test to detect antibodies. Treatment and prevention through vaccination are also summarized.
Viral infections can be diagnosed through serology, virus isolation, or direct demonstration of the virus. Serology detects virus antibodies through tests like ELISA, RIA, complement fixation, immunofluorescence, and neutralization. Virus isolation involves culturing patient samples in tissue culture or laboratory animals to detect viral growth. Direct demonstration identifies the virus or its antigens in patient samples using techniques like immunofluorescence, electron microscopy, probes, or by finding inclusion bodies in infected cells.
This document summarizes various serological tests used to detect antigens and antibodies, including:
- Primary tests like ELISA, IFAT, RIA that detect markers
- Secondary tests like agglutination, complement fixation, precipitation that detect interactions
- Tertiary tests that assess protective value of antiserum in animals
It then provides details on specific tests like agglutination, Coombs test, hemagglutination inhibition, precipitation, complement fixation, ELISA and their applications in medicine, food/plant pathology, and quality control.
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This document discusses immunity and antigen-antibody reactions and their applications in diagnostic tests for periodontal disease activity. It defines key terms like immunity, antigen, antibody, and discusses the structure and properties of antigens and antibodies. It also summarizes various antigen-antibody reactions like precipitation, agglutination, complement fixation, neutralization, and their applications in diagnosing infections. A number of diagnostic techniques for detecting antigens or antibodies are also highlighted like immunofluorescence, radioimmunoassay, ELISA, and their uses. Finally, some potential biomarkers for periodontal disease activity are mentioned.
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1) The document reviews various laboratory tests commonly used in public health surveillance such as microscopy, culture, antigen tests, PCR, and serology.
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2. Serology
Serology is the study of immune reaction in human blood.
These immune system is body defense mechanisms against
disease-causing organisms.
The principle involved with serology is the antibody-antigen
reaction.
Antigen is the substance which "provokes" the body to produce
antibodies.
Antibody is the substance which fights the invading organism.
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3. Serology…
The samples are analyzed in a laboratory to detect
either antigen or antibody.
There are several serology techniques that can be
used depending on the suspected antibodies.
Serology techniques include agglutination,
precipitation, complement-fixation, fluorescent
antibodies, and others.
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4. What Abnormal Results Mean?
As the disease gets worse, more antibodies will be
present.
If antibodies are found, you may:
Have a current infection
Have been infected in the past
Have immunity to a certain organism and are unlikely to
become sick
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5. Serologic diagnostic methods
Infectious diseases can be definitively diagnosed in only
three ways:
1. By visualizing the agent directly in clinical material
obtained from the patient.
2. By detecting a specific product of the infectious agent
in clinical material obtained from the patient.
3. By detecting an immunological response specific to the
infecting agent in the patient´s serum(antibody).
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6. Antigen - antibody reactions
Antigen - antibody reactions are the methods by which
antigens and antibodies are measured.
Ag - Ab reaction can be visualized in different ways according
to the type of the antigen, conditions of the reaction and the
medium the reaction takes place in.
When an antibody combines with a corpuscular antigen
(forming part of a cell - e.g. bacteria, virus, blood cell or inert
part with bound antigen) the cells agglutinate (form
clumps).
When an antibody combines with a non corpuscular
antigen (toxin, enzyme, microbial extract) a precipitate is
formed.
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7. When an antibody combines with an antigen
which forms part of the surface of certain cells
(e.g. red blood cells) the cells are lyzed.
Other types of serological reactions used for
antigen or antibody detection are used in
microbiology - e.g. immunofluorescent test,
EIA, ELISA (enzyme immunosorbent assays),
RIA (radioimmunoassay), which use specific
detection systems.
Antigen - antibody reactions…
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8. Serological tests can be used in two ways:
1. A known antibody can be used to detect and measure
an unknown antigen
2. A known antigen can be used to detect and measure an
unknown antibody.
Serologic tests are performed as:
a) Qualitative tests - find out presence of antibodies or
antigens in the serum.
b) Quantitative tests – conducted by serial dilutions.
Quantitative results are normally expressed in terms
of the titer of the serum.
Antigen - antibody reactions…
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9. Types of serologic reactions.
A. Agglutination
A corpuscular antigen (agglutinogen) is
agglutinated with specific antibody (agglutinin).
Agglutination can be read either visually or by
microscope.
Presence or absence of clumping is noted.
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10. I) Direct agglutination
Tests the presence of unknown microbial antigen structure in the
sample.
Slide agglutination is most often used method.
Specific antisera are prepared by immunization of animals with
bacterial strain is used as reagent.
II) Indirect agglutination
Tests the presence of antibodies in the serum.
Known antigen is used as a reagent.
E.g., Widal reaction for diagnosing typhoid and paratyphi.
Types of serologic reactions...
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11. B. Precipitation
When a specific antibody - precipitin combines with a
colloidal antigen - precipitinogen in solution or in gel it
forms precipitation.
Antigen and antibody are fully combined at the
equivalence zone.
State of optimum relation between antigen and antibody to
carry out the reaction called flocculation.
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12. Some of the serologic tests include:
Widal weilflex
Human immunodeficiency virus (HIV)
Measles
Rubella
Syphilis
Viral hepatitis (A,B,C etc )
Pregnancy tests (HCG)
Malaria RDT
Blood grouping
Anti-stereptolysin O(ASO)
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13. Syphilis
Syphilis is venereal disease caused by infectious organism called
Treponema pallidum.
When syphilis is present, the body produces Reagin antibody.
There are other disorders which can also produce Reagin.
Therefore, when the person has a positive test for Reagin, further
testing is needed to determine if the person has syphilis or some
other disorder such as leprosy, tuberculosis, malaria, etc.
False positive result is common.
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14. Non specific Tests for syphilis:
a) VDRL (Venereal Disease Research Lab)
These test is rapid and screening tests.
If positive (reactive): needs further analysis
If negative (non-reactive): syphilis absent.
Utilizes an antigen which consists of cardiolipin, cholesterol
and lecithin.
Serum must be heated to 56 C for 30 minutes to remove anti-
complementary activity which may cause false positive, if serum
is not tested within 4 hours must be reheated for 10 minutes.
VDRL used primarily to screen cerebral spinal fluid.
Results reported as reactive/non-reactive.
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15. b) RPR(rapid plasma reagin)
General screening test.
Cannot be performed on CSF.
The VDRL cardiolipin antigen is modified with choline
chloride to make it more stable and is attached to charcoal
particles to allow visual reading, the antigen comes prepared
and is very stable.
Serum or plasma may be used for testing, serum is not heated.
Non specific Tests for syphilis…
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16. Specific Treponemal Tests
1. Treponema pallidum Hemagglutination (TPHA)
Adapted to micro techniques.
Tanned sheep RBCs are coated with T. pallidum antigen.
Agglutination of the RBCs is a positive result.
2. Fluorescent Treponemal antibody absorption test (FTA-ABS)
One of the most used confirmatory test.
Highly sensitive and specific, but time consuming to perform.
3. ELISA
Tubes coated with T. pallidum antigen.
Antibody in serum attaches to antigen.
Detectable color change occurs.
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17. Typhoid and Paratyphoid Fever
Typhoid and Paratyphoid Fever is caused by Salmonella
species.
Some times it is termed as enteric fever since they
colonize the intestine.
Medically important Salmonella species are S.typhi (typhoid
fever), S.paratyphi A and B (paratyphoid fever).
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18. Salmonella have three different antigenic structures.
a) O- antigen (somatic antigen)
It is lipopolysaccharide of the outer membrane.
b) H-antigen (flagellar antigen)
H-antigen is protein, which makes the peritrichous flagella.
c) Vi- Antigen:
This is the antigen that determines the virulence, the ability to
cause disease of the organism.
Typhoid and Paratyphoid Fever
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19. Widal test
Widal test is an agglutination test for the detection of
agglutinins (antibodies) for H and O antigen for salmonella in
patients with typhoid fever and paratyphoid fever.
Is an agglutination reaction that can performed on slide or in
test tubes.
Principle: The patient serum is tested for those anti-O and
anti-H antibodies against commercially prepared O and H
antigen suspensions. Visible agglutination is seen if the anti
salmonella antibody present.
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21. Rickettsial Disease
Rickettsia is obligate intercellular parasite.
Based on their antigenic structure, the genus Rickettsia has
been divided into three main groups:
Typhus group (R. prowazeki, R. typhi),
Scrub typhus group (R. tsutsugamushi),
Spotted fever group (R. conori, R. siberica, R. rickettsi).
Rickettsia causes typhus
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22. Weilfelix test
A Weil Felix test is a type of agglutination test most
commonly used to diagnose typhus.
The reaction is based on similarity of particular antigenic
determinant, which occur in most species of pathogenic
rickettsia and in the OX-19, OX -2 strains of Proteus
vulgaris and OX-K strains of Proteus mirabilis.
In other word, Proteus antigen is used to detect
rickettsial antibody.
This could be an example of hetrophile antigen
antibody reaction.
Weil Felix test has similar principle and procedure with
Widal test.
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23. Serology of Hepatitis virus
Hepatitis virus causes inflammation of the liver.
There are 5 distinct hepatitis viruses, A, B, C, D and E
which cause chronic and acute hepatitis.
Chronic carrier state may develop and may result in liver
failure due to cirrhosis, hepatocellular carcinoma, or
fulminant hepatitis.
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24. Hepatitis A virus (HAV)
Transmitted by fecal-oral route.
First and most clinically useful is IgM antibody to HAV.
IgM indicates acute infection and disappears in 3-6
months, replaced by IgG anti-HAV.
IgG peaks during convalescence and may remain
detectable for life.
Immuno-chromatographic test are available for serologic
diagnosis of HAV.
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25. Hepatitis B (HBV)
Route of infection is usual parenteral, direct inoculation,
blood transfusions, maternal to fetus or newborn.
Laboratory diagnosis involve the detection of three marker
systems.
1. Hepatitis B surface antigen (HBsAg) is the first to appear,
appears 2 to 4 weeks during late incubation, marker of choice
for recent infection.
2. Anti-hepatatis B surface antigen (anti-HBs) is the last
antibody to appear, may persist for life.
3. IgM antibody to hepatitis B core antigen (anti-HBc) may be
the only detectable marker during the core window, differentiates recent
infection from chronic carrier state.
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26. Hepatitis C Virus
Clinically and epidemiologically similar to HBV.
Sixty to 70% of HCV patients will develop chronic
hepatitis, 10-20 % cirrhosis and 15% hepatocellular
carcinoma.
HCV and HBV may be present as co-infections.
Present of HCV antibodies only indicates present or
past infection.
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27. Human Immunodeficiency Virus (HIV)
Causes Acquired Immunodeficiency Syndrome (AIDS).
Characteristics of the virus
Icosahedral, enveloped virus of the lentivirus
subfamily of retroviruses.
Retroviruses transcribe RNA to DNA.
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28. HIV test algorism
1) KHB
If the test for KHB is non reactive then the test is reported
negative because the test is very sensitive.
If the test for KHB is reactive we proceed to the next step or test
to which is very specific.
2) Stat pack
The test is more specific than the former one.
If the test result is reactive and agree with KHB test result; then
the test is reported positive but if the test result is negative and not
agree with KHB test result we proceed to third test.
3) Unigold (tie-breaker)
The test is more specific and sensitive.
Any results of the test is reportable. i.e. if reactive the test is
reported positive and if non reactive reported as negative.
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30. Pregnancy tests
Human chorionic gonadotropin (HCG) is a hormone
secreted by placenta during pregnancy.
Its production stimulates secretion of progesterone by the
ovary.
Human chorionic gonadotrophin appears in urine, blood and
amniotic fluid.
The serum and urine level rise rapidly during gestation,
reaching a peak at six to eight weeks, after which there is a
steady decline.
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31. Immunologic test of pregnancy
Immunologic test could be qualitative and quantitative.
Qualitative estimation of HCG in urine is used for early
detection and confirmation of pregnancy.
The test is less expensive and quicker test.
Sample could be urine and blood.
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32. Factors Affecting Pregnancy Tests
False Negative may occur in conditions like:
test is performed too early.
Urine too diluted -falsely low levels of HCG.
Ectopic pregnancy.
False positive may occur in conditions like:
Proteinuria and hematuria
Test after abortion
Bleeding
Turbidity of urine
Bacterial contamination
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