Download Streptococcus pneumoniae and Staphylococci

Chapter 8
Coccus
Pathogenic cocci
• pyogenic coccus
• according their staining colour
– G(+) ：
Staphylococcus, Streptococcus, Pneumococcus
– G(-) coccus ：
– Meningcoccus, Gonococcus
The Staphylococci
Staphylococcus
Morphology
Morphology :
Shape :
Gram staining :
Special structure :
Distribution :
Kinds: S. aureus
Staphylococcus
Culture
1.Liquid medium：
Turbidity growth
2.solid medium：
turbidity growth
Oil colony（gold、white、lemon）
S.aureus : Blood agar plate
（βhemolysis）
Staphylococcus
Biochemical reaction
(－)
(＋)
(-)
(+)
catalase test
mannitol test
Staphylococcus
Antigenic structure
★staphylococcal protein A, SPA
Capsule
polysaccharide
SPA
Staphylococcus
resistance
– More resistance than other non-sporeforming
bacteria
– Variably sensitive to many antimicrobial drugs
– Drug-resistant strains increase, and become the
most common hospital pathogen
control
drugtreated
Main characteristics of three species of staphylococci
property
S aureus
S epidermids
S saprophyticus
Pigments of colony
Gooden yellow
White
White or gray
Coagulase
+
－
－
Α-hemeolysin
+
－
－
SPA
+
－
－
Carbohydrate
+
+
－
Phage typing
+
－
－
pathogenicity
+
+/－
－
fermention
Staphylococcus
Toxin and enzymes
1. coagulase
2. heat-stable nuclease
3. staphylolysin
4. leukocidin
5. enterotoxin
6. exfoliative toxin, exfoliatin
7. toxic shock syndrome toxin 1，TSST-1
8.Other enzymes
Staphylococcus
hyaluronidase
hyaluronic acid
Pathogenesis of staphylococcal infections
Staphylococcus
pyogenic inflammation
food poisoning
scalded skin syndrome
toxic shock syndrome, TSS
Pseudomembrane colitis,PMC
furuncle
impetigo
Folliculitis
carbuncle
Microbiologic diagnostic test
specimens pus, blood, tracheal aspirate, et.al
smears
G+ Staphylococci
isolated
culture
Growth
phenomenon
Biochemical
reaction
pigment，hemolysis
Catalase test
Coagulase test
Susceptibility test
The Streptococcus
I. Biological characteristics
Streptococcus
Morphology
Morphology ：
Shape：
Special structure：
Gram staining：
(1).Hemolytic activity:
(i) -hemolytic streptococcus
*Incomplete hemolysis, green coloration of the medium
surrounding the colony.
*Opportunistic pathogens – subacute bacterial
endocarditis (SBE).
(ii) -hemolytic streptococcus (or pyogenic streptococcus)
Complete hemolysis, major human pathogens
(iii) -streptococcus
No hemolysis, no pathogenicity.
Staphylococcus
Culture
1.Liquid medium：
2.Blood agar plate ：
Long chain
and
deposit
S. pyogenic
Antigenic structure
(group-specific antigen).
19 groups Group A
streptococci are main
human pathogens
Polysaccharide Ag
M protein
type-specific antigen
M protein:
*presents in cell wall (group A)
*Anti-phagocytosis
*adhere to epithelial cells
*clump platelet and leukocyte
*heat stable; acid stabl
S. pyogenic
resistance
*heat labile: 60℃,30 min
*antibiotics sensitivity: penicillin G ,etc.
II. pathogenicity
(1).Invasiveness
(i).surface structure
*LTA(lipoteichoic acid): adhere to sensitive cell
(epithelial cell; platelet; RBC; WBC; lymphocyte;
mucous membranes)
F protein
* M-protein : anti-phagocytotic
 M-Ag
Ab
hypersensitivity
(glomerulonephritis)
 Common antigen--- cross-reacts heart myosin
autoimmunity------- rheumatic fever
Toxins and enzymes
Hyaluronidase (spreading factor): – Pyrogenic Exotoxins
(ErythrogenicToxin)
Streptokinase (SK ):
Streptodornase (SD):
– streptolysin,SL
•
S. pyogenic
Pathogenesis & Clinical Findings
2. Diseases of streptococcal infection
(1). local purulent infections:
(2). systemic infection :
Erysipelas
Scaret fever
Tonsillitis
(3). Hpersensitivity response :
(i) acute glomerulonephritis ( group A)
(many types of group A streptococci)
mechanism:
*immune complex  (deposition) glomerular
basement
membrane

type
III
hypersensitivity
*common Ag  cross-reacts  glomerular
basement type II hypersensitivity
(ii) Rheumatic fever
(many types of group A streptococci)
mechanism:
*immune complex  (deposition) heart,
joints  type III hypersensitivity
*common Ag  cross-reacts  heart
type II hypersensitivity
S. pyogenic
Diagnostic Laboratory Tests
• Specimens
– A throat swab, pus, or blood
• Smears
– Smears from pus often show single cocci or
pairs rather than definite chains.
• Culture
• ASO test: ASO titer > 1: 400 units, help
to diagnose rheumatic fever.
Streptococcus
*Treat the pharyngitis and tonsillitis in time,
avoid streptococcal hypersensitive disease.
*Antibiotics and chemical agents:
penicillin G for the first choice
S. pneumoniae
S.pneumoniae
Morphology
Morphology ：
Shape：
Special structure：
Gram staining：
S.pneumoniae
Culture
1.Blood agar plate ：
2.Liquid medium：
S.pneumoniae
Biochemical reaction
Not optochin sensitive
• α-hemolytic streptococcus
and
• S.pneumoniae
Bile bacteriolysis test
Optochin sensitive test
optochin sensitive
S.pneumoniae
Capsule prominent virulent strains
S.pneumoniae
R型
S型
?
Pathology
• pneumococcal pneumonia ---pneumonia
Diagnostic Laboratory Tests
• specimen
– Blood cultures, sputum, pleural fluid, and spinal fluid
• Stained Smears:
– A Gram-stained film of rusty-red sputum shows typical
organisms, many polymorphonuclear neutrophils, and
many red cells.
• Capsule Swelling Tests
– identification of pneumococci and possible typing
• Culture--- Sputum cultured on blood agar
Therapy
– most strains susceptible to penicillin
a large daily dose of penicillin
– resistance is common
Drug sensitivity testing is therefore essential
– Polyvalent vaccines that contain capsular
antigens to preventing recurrences
Neisseria
• Gram negative
• diplococci
• oxidase positive
• Culture:
chocolate agar
* heated blood
Gram stain of pure culture
exudate
Using the Gram stain in patient specimens, the organisms are most often
observed in polymorphonuclear leukocytes
N. meningitidis
Main Pathogenic factor:
LPS
Capsule
have
Plasmid
rarely have
Caused disease
meningitis
N. gonorrhoeae
PILI
not have
have
genital infection
prostatitis
Urethritis
cervicitis
Endometritis
Purulent conjunctivitis Infection in
newborns during vaginal delivery
blindness
Prevention and treatment
*penicillin----*silver nitrate----conjunctivitis
1. Lancefield Grouping of Streptococci (Group A,
B, etc.) is based on:
√A．Cell wall carbohydrate
B．M protein
C．LPS
D．Peptidoglycan
E．DNase production
2. Vaccination against the Streptococcus pneumoniae capsule
is protective against pneumonia because:
A．There is only a single serotype of pneumococcal capsular
antigen.
√B．Anti-capsular antibody opsonizes the organisms in the
lung so they can be phagocytosed.
C．It stimulates cell-mediated immunity so that the
organisms are killed in the lung.
D．It prevents the pneumococci from colonizing the throat
and then getting into the lung.
E．It inhibits the production of alpha hemolysis.
3. Acute Rheumatic Fever:
A．Usually appears 3 weeks after primary skin infection
with Group A streptococci.
the result of a cross-reactive immune response to
√B．Is
streptococcal antigens.
C．Is manifested only as inflammation of the heart
muscle.
D．Will not occur if symptoms of primary streptococcal
disease disappear within 3 days.
E．NONE OF THE ABOVE.
4. You treat a patient with pharyngitis caused by Group A
streptococci with amoxicillin. The pharyngitis resolves, but
now the patient experiences a vaginal yeast infection.
Which is the most likely explanation for this phenomenon?
A. The pharyngitis was really oral thrush and the yeast spread
through the alimentary and genital tracts.
B. The Streptococcus pyogenes bacteria were keeping the
yeast in check.
C. The antibiotic induced a hypersensitivity reaction.
√D. The normal flora that controlled the yeast was inhibited by
the antibiotic.
E. None of the above are likely.
5.To differentiate the viridans Streptococci from
Streptococcus pneumoniae, which of the following
tests is done?
A. A co-agglutination test with Staphylococcus aureus
and antibody to the pneumococcal capsule
B. A test that examines resistance to bacitracin
C. A coagulase test
D.
√ A test that examines sensitivity to optochin.
E. A test that examines resistance to novobiocin.
6 .To determine if a patient with a newly diagnosed heart
murmur had a recent Group A Streptococcal infection
that could have caused rheumatic fever, which is the most
effective test to be done?
A. Throat swab and culture, looking for beta hemolytic
colonies.
√B. An M protein antibody test.
C. An anti-DNAase B test.
D. Examine the patient for a red, sandpaper-textured rash.
E. Blood culture.
7.Which of the following can produce
autoenzyme:
A.Bacillus proteus
B.Bacillus typhi murium
C.Vibrio cholerae
D.Meningococcus
√
E.Clostridum tetani
8.The bacteria which can produce SPA is
√A.Staphylococcus aureus
B.Meningococcus
C.Gonococcus
D.aeruginosus Bacillus
E.none of above
9.The test which can differentiate S.aureus
from other species is
√A. coagulase-test
B.Catalase test
C.Lactose ferment test
D. mannitol test
E.none of above
10.Which of the following substances are
produced by S.aureus except
A. coagulase
B.staphylolysin
C. leukocidin
D. exfoliative toxin
√E.streptokinase