bacterial serology (streptococcal) Flashcards
The Streptolysin O Antigen is fixed on the surface of the latex particles. These latex particles are mixed with the patient’s diluted serum on a slide and rotated.
anti-streptolysin O (ASO) latex agglutination test
conditions that are the consequence of a previous disease or injury
sequelae
a neutralization test that can demonstrate recent streptococcal infection.
anti-DNase B
ASO titer
- The ASO titer begins to increase approximately (?) days after infection and peaks after (?) to (?) weeks.
- Principle: (?), SLO is added to serial dilutions of patient serum, along with group O RBCs as indicator cells.
- ASO titer is reported as the (?) of highest dilution that shows no hemolysis & is expressed in (?) units.
- 7
- 4, 6
- neutralization
- reciprocal
- todd
Patient antibodies (if developed due to past infection with Streptococcus pyogenes) neutralize the hemolytic activity of the streptolysin O (SLO) reagent. As a result, when red cells are added, SLO will be incapable of lysing the said cells (no hemolysis).
ASO test
- SLIDE AGGLUTINATION SCREENING TEST FOR DETECTION OF ANTIBODIES TO SEVERAL STREPTOCOCAL ANTIGENS.
- SHEEP RBC’S COATED W/ STREPTOLYSIN, STREPTOKINASE, HYALURONIDASE, DNAse, so that ANTIBODIES to any streptoccal antigen can be detected
streptozyme testing
- Healthy adults have ASO titers of (?) Todd units, with the usual titer decreasing after (?) years of age.
- A (?) rise in titer above a previous level is of greater significance than a single titer
- <166
- 50
- 30%
Streptococcal pyoderma, characterized by vesicular lesions on the extremities that become pustular and crusted.
impetigo
- caused by a strain of S. pyogenes that produces an erythrogenic toxin, which results in a characteristic rash. Fever and sore throat are also present.
- Distinct rash initially appears on the neck and chest and then spreads all over the body.
- results from infection with a GAS that elaborates streptococcal pyrogenic exotoxins (erythrogenic toxins).
scarlet fever
streptolysin O enzymes
- DNase B
- hyaluronidase
- NAD
- streptokinase
Upper respiratory tract infections caused by (?):
a. Sore Throat
b. Pharyngeal Edema
S. pyogenes
Cross-reactions of antibodies produced against streptococcal antigens and human heart tissue
acute rheumatic fever
Symptoms include fever, chills, severe sore throat, headache, tonsillar exudates, petechial rash on the soft palate, and anterior cervical lymphadenopathy
pharyngitis
Deposition of antibody-streptococcal antigen complexes in kidney results in damage to glomeruli
glomerulonephritis
streptolysin O or S
- Is a non-antigenic, oxygen-stable enzyme.
- It causes hemolysis by disrupting the selective permeability of the RBC membrane.
streptolysin S
Pyrogenic exotoxins A, B, and C are responsible for the rash seen in (?) and also appear to contribute to pathogenicity
scarlet fever
ASO test
- Red cell control = (?)
- SLO reagent control = (?)
- no hemolysis
- complete hemolysis
Gram positive cocci, Beta-hemolytic, Divided to serogroup A through O
streptococcal sero
contain lipoteichoic acid, important in the adherence of the organism to human epithelium and the initiation of infection
fimbrae
streptolysin O or S
- bacterial toxin produced by virtually all strains of S.pyogenes;
- released during infection as indicated by antibody production to it;
- Molecular weight = 70 000;
- in its reduced state, brings about the lysis of red and white blood cells
- Is an oxygen-labile enzyme that causes hemolysis by binding to cholesterol in the RBC membrane.
- It is antigenic, and the presence of antibodies to SLO is an indicator of recent streptococcal infection.
streptolysin O
Manifestation of S.pyogenes Infection
- acute RF
- glomerulonephritis
MAJOR VIRULENCE FACTOR of S.pyogenes; cell protein found in association with hyaluronic capsule
M protein
mediates epithelial cell attachment,
protein F
Skin infections caused by (?) include:
a. Cellulitis
b. Impetigo
c. Erysipelas
S. pyogenes
