Cocci. Staphylococcus “staphyle” in Greek Staphylococcus S.aureus: most virulent species....
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Transcript of Cocci. Staphylococcus “staphyle” in Greek Staphylococcus S.aureus: most virulent species....
Cocci
Staphylococcus
“staphyle”
in Greek
Staphylococcus
• S.aureus: most virulent species.
• S.epidermidis: opportunistic pathogen.
• S.saprophyticus: rarely cause human diseases.
Biological characteristics
• Shape and structure • Size: 0.5-1.0 m in diameter• Shape: spherical• Arrangement: grape-like• Structure: capsule
non-motile
non-sporulating• Staining: G+
Biological characteristics
• Cultivation• Requirements
media: all-purpose media
gas: facultative anaerobes
specially: tolerating 10-15% NaCl
Growth properties on solid medium: small colony
with various pigments
on blood agar: zone of complete hemolysis (-hemolysis)
Biological characteristics
S.aureus
• Biochemical reactions
Biological characteristics
Catalase test “+” Staphylococci: “+” Streptococci: “-”
Mannitol Fermentation “+”
S. aureus: “+”;
S.epidermidis & S.saprophyticus: “-”;
SPA
capsule
teichoic acid
peptidoglycan
Biological characteristics
Capsules teichoic acid , peptidoglycanProtein antigen: SPA
• Antigenic composition
SPA (Staphylococcal Protein A )
• Characteristics
nonspecific bind to the Fc fragment of IgGs
SPA(staphylococcal protein A)
SPASPAIgGIgG
Fc receptorFc receptor
PhagocytePhagocyte
BACTERIUMBACTERIUM
• Function: – virulence factor
• Anti-phagocytosis• damage platelet• induce hypersensi
tivity and inflammation
coagglutination test SPA-coated S.aureus is used as Ab carriers
SPA (staphylococcal protein A )
S.aureus Ab
Biological characteristics---Classification
• Based on the pigments and chemical reactions
Properties S. aureus S. epidermidis S. sarprophyticus
Pigment Golden yellow White Citrine
Coagulase + - -Mannitol + - -
Thermostable nuclease + - -α-hemolysin + - -
SPA + - -Pathogenicity strong Weak -
• Based on coagulase Coagulase” +”: e.g., S. aureus Coagulase” -”: e.g., S. epidermidis & S. saprophytic
us
• Phage typing S. aureus: 3 phage groups, 26 phage types.
group 1: TSST-1-producing strains group 2: exfoliative toxin-producing strains group 3: enterotoxin-producing strains
----is of epidemiological value
Biological characteristics---Classification
Biological characteristics
• Resistance: • Drying• Heat• high concentration of salt (10-15% NaCl)
• Sensitivity: • basic dyes (crystal violet)
• several antibiotics (penicillin, vancomycin) MRSA (methicillin resistance S.aureus)
Pathogenicity (S.aureus)
• Virulence factors Surface structure capsules, peptidoglycan, teichoic acid, SPA
Enzyme Toxin
• Virulence factorsEnzymes: coagulase 血浆凝固酶
heat-stable nuclease 耐热核酸酶hyaluronidase 透明质酸酶 lipase 脂酶β – lactamase β- 内酰胺酶
Exotoxins: Hemolysin溶血素Leukocidin 杀白细胞素Staphylococcal enterotoxin 葡萄球菌肠毒素TSST-1 毒性休克综合征毒素 -1Exfoliative toxin 表皮剥脱毒素
Pathogenicity (S.aureus)
Enzyme
• Coagulase: • An enzyme that converts fibrinogen into fibrin
causing the coagulation of blood. • Classification:
Free coagulase 游离凝固酶 Bound coagulase 结合凝固酶
Coagulase• Biological activity
Antiphagocytosis
Inhibit the damage of bactericidal substances
Formation of limited abscess
• Significance
criterion for identification of S. aureus (pathogenic)
Coagulase test
Tube test for free coagulase Slide test for bound coagulase
Hemolysins
• Roles: damage membrane permeability;
cytotoxic effects on phagocytes and tissue cells
• Four kinds: -Lysin
-Lysin
-Lysin
-Lysin
S.Aureus in blood agar
Leukocidin • Biological activity
Impairment of membrane of WBC
Staphylococcal enterotoxin
• Source: 50% S. aureus
• Types: A 、 B 、 C1-3 、 D 、 E 、 G 、 H
• Chemical and physical characteristics
Protein
Heat stable (100 , 30 min)℃Resistant to gut enzymes
• Mechanism: act on vomiting center, superantigen
• Disease: food poisoning
Superantigens and the non-specific stimulation Superantigens and the non-specific stimulation
of T cellsof T cells
Toxic Shock Syndrome Toxin-1(TSST-1)
• Source: phage group of Ⅰ S. aureus
• Biological activity
feverIncrease the sensitivity to endotoxinsuperantigen
• Disease: TSS
Exfoliative toxin
• Sourcephage group of Ⅱ S. aureus
• Biological activity
protease activity
• Disease: SSSS
Staphylococcal scalded skin syndrome
Pathogenicity• Disease Invasive infection/pyogenic infection • local infection: folliculitis; boil ; carbuncle ; impetigo • organ infection: pneumonia; meningitis
• Systemic infection: Septicemia; pyemia Toxin-associated diseases
hair folliculitis
boil
Pathogenicity
Toxin-associated diseases • Food poisoning (enterotoxin) • TSS (Toxic shock syndrome)
• SSSS (staphylococcal scalded skin syndrome) • Staphylococcal enterocolitis -dysbacteriosis
Staphylococcal scalded skin syndrome (SSSS)
Most often occurs in infants
and young children
CNS• Coagulase-Negative Staphylococci• Virulence factor: slime• Antibiotic-resistance• Opportunistic infection• S. epidermidis, S.saprophyticus
Diseases caused by coagulase-negative staphylococci
• Diseases: – urinary tract infection– Bacterial endocarditis– Septicemia– Infections associated with indwelling
devices
Laboratory diagnosis • Specimen • Direct smear and Gram stain• Isolation and identification Primary criterions: coagulase test, thermostable nuclease gold yellow pigmentation -hemolysis mannitol fermentation
• Enterotoxin test (animal test) • Antibiotic susceptibility tests
Control
Prevention
Aseptic measures
hygiene
Nosocomial infection
DrugresistanceTreatment
Antibiotic susceptibility tests
Autovaccino-therapy
Streptococcus
• Shape: G+ cocci in chains
capsule
cell membrane
cell wall
pilus-like structure
• structure: capsule
pilus-like (LTA-M protein)
carbohydrate antigen protein antigen: M, R, Tcarbohydrate antigen
and protein antigen
• Classification Hemolytic activity -hemolytic strep. Incomplete hemolysis Opportunistic pathogens e.g., S.pneumoniae, S.virida
ns -hemolytic strep. Complete hemolysis()
Major human pathogens e.g., S. pyogenes -streptococcus No hemolysis, No pathogenicity e.g., enterococci.
a
b
c
• Classification Antigenic structure ( Lancefield 血清学分群 )
• C carbohydrate antigen – group-specific antigen – 20 groups (A~H, K~V)– Group A- main human pathogens
• Protein antigen – type-specific antigen – M, R, T protein – Group A >100 types
capsule
Cell wall
protein
Polysaccharide
Peptidoglycan
Streptococcus
• Classification Biochemical reaction
生化反应 血清学分类 溶血反应化脓性链球菌咽峡炎链球菌无乳链球菌停乳链球菌牛链球菌草绿色链球菌肺炎链球菌
A
A C F G 无相关性B
C G
D
无相关性
溶血 溶血,偶见溶血或不溶血 溶血,偶见不溶血 溶血 溶血或不溶血,偶见 溶血 溶血或不溶血 溶血
S. pyogenesS. pyogenes
Biological characteristics
• shape and size: spherical, 0.6 ~ 1.0 μm in diameter
structures: capsule (hyaluronic acid)
nonmotile
nonsporeforming
highly nutritive -hemolysis
catalase negative
Pathogenicity
• Virulence factorsSurface structures
Enzymes
Exotoxins
fibronectinfibronectin
lipoteichoic acidlipoteichoic acidF-proteinF-proteinM proteinM protein
epithelial cellsepithelial cells
Pathogenicity• Virulence factors
Surface structures adhesin: LTA
F protein M protein: anti-phagocytosis
cross-reactive antigen
Pathogenicity
• Virulence factors
Enzymes
Hyaluronidase
Streptokinase (SK)
Streptodornase (SD)
(DNase, DNaseB-Ab)
Pathogenicity
• Virulence factors
Exotoxins
Streptolysin (hemolysin)
Erythrogenic toxin
Streptolysins
• streptococci group A, C, and G;• Classification:
Properties Streptolysin O (SLO) Streptolysin S (SLS)
O2 oxygen-labile oxygen-stable
Antigenicity Strong (ASO test) Weak
Chemical Protein Polypeptide
Activity toxic to a variety of cell types
Erythrogenic toxin
• Pyrogenic toxin /scarlet fever toxin
• Protein
• Antigenicity
• Superantigen
• Scarlet fever
Pathogenicity
• Pyogenic infection:– Local purulent infections
pharyngitis, tonsillitis,
puerperal fever 产褥热 erysipelas 丹毒 ,
cellulitis 蜂窝织炎 impetigo
Systemic infection: septicemia
Abscess with surrounding
cellulitis
Erysipelas
Erysipelas on
the cheek
• Toxin-associated diseases scarlet fever
• Hypersensitive disease Acute glomerulonephritis
Rheumatic fever
Hypersensitivity type II & III
specimen
Direct smear
-hemolytic strep.
Isolation and cultivation
S.aureus
S.pneumoniae
Laboratory diagnosis
PYR testS. Pyogenes 阳性
Laboratory diagnosis • Serologic diagnosis
ASOT (anti-SLO test)
a neutralization test between the toxin (SLO) and its specific anti-toxin (ASO) helping to diagnose rheumatic fever and acute glomerulonephritis
positive standard : ASO titer >1:400
Control
• Treat the pharyngitis and tonsillitis in time
• Antibiotics: penicillin G for the first choice
S. pneumoniae (Pneumococcus )
General properties • G+, arranged in pairs, l
ancet-shape• Capsule
– Polysaccharide– Type-specific antigen
• Fastidious blood agar -hemolysis
(Bile solubility test)
(-) (+)
General properties
• Autolysis
• Bile solubility test: “+”
Pathogenesis
• Virulence factor• Capsule• Neuraminidase• Pneumolysin• LTA, peptidoglycan
• Main disease• Pneumonia• Others: middle ear infections (otitis media), si
nusitis, meningitis, septicemia
Non-typical pneumonia
Laboratory diagnosis
• Identification of pneumococci from S.viridans
bile solubility test
optochin sensitivity test
quellung reaction (capsular swelling test)
positive negative
Control
• Treatment: penicillin G
• Prevention: polysaccharide vaccine (for children and elderly)
Viridans streptococciViridans streptococci
• S.mutans• S.anginosus• S.salivarius• S.mitis• S.sanguis
bile solubility test (-)optochin sensitivity test(-)
dental caries
subacute bacterial endocarditis
S.agalactiaeS.agalactiae
• Group B streptococcus, GBS
• Transmission – vaginal flora
• Disease– neonatal meningitis– neonatal pneumonia– septicemia
S. suisS. suis
Neisseria
Neisseria
N. gonorrhoeae
N. meningitidis
N. sicca
N. subflava
N. mucosa
N. lactamica
General properties
• Shape and structure– G- diplococci
Coffee bean-shaped
kidney-shaped– Lipooligosaccharide
(LOS)– Pili
• Closely related
DNA homology 70%
General properties
• Cultivation– Fastidious: chocolate agar plate
– Obligate aerobes, 5 ~ 10%CO2
– Autolysis (N.meningitidis)– Oxidase positive– Fermentation certain sugars
• N. gonorrhoeae : Glucose• N. meningitidis : Maltose & Glucose
General properties
• Very weak: cool, heat, drying, disinfectants
Fragile - don’t survive long outside the host
N. meningitidis
Capsule
LOS
IgA1 protease
PILIOuter Membrane Proteins
N. gonorrhoeaeVirulence Factors
Similar, but –Differencesin utilization
LOS
PILIOuter Membrane Proteins(Por,Opa, Rmp proteins)
IgA1 protease
Pathogenesis
iron-binding proteins
iron-binding proteins
N. gonorrhoeae /gonococcus
– Nonpiliated gonococci not virulent
– Phase variation turns pilus production on/off
– Antigenic variation
PILI
Porin proteins (Por) = prevent phagolysosome fusion & allow intracellular survival [protein I]
Opacity proteins (Opa) = binding of organisms to epithelium [protein II]
Reduction-modifiable proteins (Rmp) = protection against bactericidal antibodies [protein III]
Outer Membrane Proteins
N. gonorrhoeae /gonococcus
N. meningitidis/menigococcus
– vascular damage– skin rash– renal failure– shock– disseminated intravascular coagulation (DIC)
LOS (lipooligosaccharide)
Capsule 13 serotype A, B, C, Y, W-135
N. meningitidis
Capsule
LOS
IgA1 protease
PILIOuter Membrane Proteins
N. gonorrhoeaeVirulence Factors
Similar, but –Differencesin utilization
LOS
PILIOuter Membrane Proteins(Por,Opa, Rmp proteins)
IgA1 protease
Pathogenesis
iron-binding proteins
iron-binding proteins
NO capsuleX
• Gonorrhea – AdultsTransmission: STD (sexually transmitted diseas
e)Clinical disease: Genitourinary tract infection Male-Urethritis Female-Urethritis, cervix inflammation PID (Pelvic Inflammatory Disease)
Sterility
Disease
Gonorrhea
Symptomatic infections are notably PURULENT
Urethritis
Disease
• Gonorrhea – NewbornsOphthalmia neonatorum
Purulent conjunctivitis
Ophthalmia neonatorum Infection in newborns during vaginal delivery
Gonorrhea
Disease• Source: patients and carriers
Transmission: respiratory tract
nasopharynx→local infection→septicemia→meningitis
Disease: epidemic cerebrospinal meningitis
Laboratory diagnosis
• Specimens• Smears• Culture
– Thayer-Martin VCN– Oxidase test– Maltose fermentation
• Antigen Detection and Enzyme Immunoassays– Radioimmunoassay– ELISA – SPA coagglutination test
• Others– DNA Probe Hybridization
• Antibiotic
• 1%Silver nitrate-- ophthalmia neonatorum
• No effective vaccine
Treatment & Prevention
N. gonorrhoeae
Antibiotic Resistance
• Increase in penicillin resistance since 1976– PPNG (penicillinase-producing N. gonorrhoeae )– plasmid mediated– due to beta lactamase production
• Tetracycline resistance recognized in 1985– TRNG (Tetracycline resistance N. gonorrhoeae )– due to chromosomal mutation
• Sensitive to quinolones, cephalosporins
• Antibiotic
• 1%Silver nitrate-- ophthalmia neonatorum
• No effective vaccine
Treatment & Prevention
N. gonorrhoeae
• Treatment penicillin: the first of choice
sulfasulfonamide
• Prevention immunization: capsule polysaccharide
group B meningitis
N. meningitidis
Treatment & Prevention
Pathogenic cocci/Pyogenic cocci
Neisseria meningitidis
Neisseria gonorrhoeae
G+ cocci
G- cocci
Staphylococcus aureuStreptococcus pyogenes Streptococcus pneumoniae
Neisseriae of medical importanceProperties N. meningitidis N. gonorrhoeae
Gram stain Gram-negative Gram-negative
Capsule Yes No
Potal of entry Respiratory tract Genital tract
Virulence factors
Pili
Outer membrane protein
IgA1-protease
Iron-binding protein
LOS, Capsule
Pili
Outer membrane protein
IgA1-protease
Iron-binding protein
LOS
Disease Epidemic cerebrospinal meningitis
Gonorrhea (adults)
Ophthalmia neonatorum (newborns)
Prevention Polysaccharide vaccine
Tetracycline, erythromycin ointment or AgNO3 for ophthalmia
No vaccine for gonorrhea