Streptococcal Serology
Terry Kotrla
Introduction
• Gram-positive
• Beta hemolytic
• Spherical, ovoid or
lancet shaped
• Pairs or chains
Divided into Serotypes or groups
• Two major outer proteins M and T
• Eighteen interior proteins knows as
Lancefield grouping
• Streptococcus pyogenes belong to
Lancefield group A
• M protein chief virulent factor
Numerous Exoantigens
• Exoantigens are produced and excreted and
include:
–
–
–
–
–
Streptolysin O
Dnase
Hyaluronidase
Nicotinamide Adenine Dinucleotidase
Streptokinase
• Patients react to exoantigens by producing
antibodies
Characteristics
• Two major sites of infection
– Upper respiratory tract
– Skin
• If infections left untreated can lead to
post-streptococcal sequelae
– Acute glomerulonephritis
– Rheumatic fever
Upper Respiratory
•
•
•
•
•
Sore Throat
Tonsillar exudate
Fever
Chills
20% school children
carriers
Skin
• Impetigo
– Lesions on
extremities
– Commonly on face
– Pustular and crusty
Suppurative Complications
• Suppurate -To generate pus; as, a boil
or abscess suppurates.
• Erysipelas
• Necrotizing fasciitis
• Scarlet fever
Erysipelas
– Infection involves the dermis and lymphatics and
is a more superficial subcutaneous infection of the
skin than cellulitis.
– characterized by intense erythema, induration and
a sharply demarcated border.
Necrotizing Fasciitis
Scarlet Fever
• Strep bacteria
produces a toxin
that causes a
rash
• Sandpapery
• Peels
Non-Suppurative
• Inflammatory response elsewhere in the
body.
• Damaging sequelae to strep infection
– Rheumatic Fever
– Post-Streptococcal glomerulonephritis
Rheumatic Fever
• Delayed consequence of an untreated upper
respiratory infection with group A
streptococci
• Causes serious, debilitating damage to the
heart.
• Associated with large amount of M protein
and a capsule
• Due to immune response against Strep
antigens similar to heart antigens.
Rheumatic Fever
This is the heart of a 44 year old woman who
had rheumatic fever and had been treated for
congestive heart failure for about one year.
Poststreptococcal glomerulonephritis
• Follows strep infection of skin or
pharynx
• Characterized by damage to glomeruli
of kidneys
• Deposition of Ag-Ab complexes,
activation of complement.
• Inflammatory response causes damage.
Poststreptococcal glomerulonephritis
• Most common in children 2-12
• Symptoms:
– Hematuria
– Proteinuria
– Edema
– hypertension
Poststreptococcal glomerulonephritis
• The scattered capillary wall granular deposits
in acute poststreptococcal glomerulonephritis
also stain for complement
(immunofluorescence with antibody to C3)
Laboratory Testing
•
•
•
•
Culture and identification
Rapid Strep Tests from throat swab
Detection of Streptococcal antibodies
Anti-Streptolysin O (ASO) titer