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
Biological characteristics
Growth properties
on solid medium: small colony
with various pigments
on blood agar: zone of
complete hemolysis
(hemolysis)
S.aureus
Biological characteristics
• Biochemical reactions
Catalase test “+”
Staphylococci: “+”
Streptococci: “-”
Mannitol Fermentation “+”
S. aureus: “+”;
S.epidermidis & S.saprophyticus: “-”;
Biological characteristics
• Antigenic composition
Capsules
teichoic acid , peptidoglycan
Protein antigen: SPA
capsule
peptidoglycan
teichoic acid
SPA
SPA (Staphylococcal Protein A )
• Characteristics
nonspecific bind to the Fc fragment of IgGs
SPA(staphylococcal protein A)
• Function:
– virulence factor
Phagocyte
• Anti-phagocytosis
Fc receptor
• damage platelet
• induce
IgG
hypersensitivity
and inflammation

coagglutination test
SPA-coated S.aureus is
used as Ab carriers
BACTERIUM
SPA
SPA (staphylococcal protein A )
S.aureus
Ab
Biological characteristics---Classification
• Based on the pigments and chemical
reactions
S. sarprophyticus
S. epidermidis
S. aureus
Properties
Pigment
Coagulase
Mannitol
Thermostable nuclease
α-hemolysin
SPA
Pathogenicity
Golden yellow
+
+
+
+
+
strong
White
－
－
－
－
－
Weak
Citrine
－
－
－
－
－
-
Biological characteristics---Classification
• Based on coagulase
 Coagulase” +”: e.g., S. aureus
 Coagulase” -”: e.g., S. epidermidis & S.
saprophyticus
• 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
• 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
Pathogenicity (S.aureus)
• Virulence factors
Enzymes: 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-1
Exfoliative toxin 表皮剥脱毒素
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
of T cells
Toxic Shock Syndrome Toxin-1(TSST-1)
• Source: phage group Ⅰ of S. aureus
• Biological activity
fever
Increase the sensitivity to endotoxin
superantigen
• Disease: TSS
Exfoliative toxin
• Source
phage group Ⅱ of S. aureus
• Biological activity
protease activity
• Disease: SSSS
Staphylococcal
syndrome
scalded
skin
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
Aseptic
measures
Nosocomial
infection
Prevention
Treatment
Antibiotic
susceptibility
tests
Autovaccinotherapy
Drug
resistance
hygiene
Streptococcus
• Shape: G+ cocci
in chains
capsule
•
structure:
capsule
cell membrane
cell wall
carbohydrate antigen
and protein antigen
pilus-like structure
pilus-like (LTA-M protein
carbohydrate antigen
protein antigen: M, R, T
• Classification
 Hemolytic activity
• -hemolytic strep.
Incomplete hemolysis
Opportunistic pathogens
e.g., S.pneumoniae,
S.viridans
• -hemolytic strep.
Complete hemolysis()
Major human pathogens
e.g., S. pyogenes
• -streptococcus
No hemolysis,
No pathogenicity
e.g., enterococci.
a
b
c
• Classification
Cell wall
 Antigenic structure
( Lancefield 血清学分群 )
• C carbohydrate antigen
– group-specific antigen
– 20 groups (A~H, K~V)
Streptococcus
– Group A- main human pathogens
• Protein antigen
– type-specific antigen
– M, R, T protein
– Group A >100 types
capsule
protein
Polysaccharide
Peptidoglycan
• Classification

Biochemical reaction
生化反应
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
血清学分类
A
A C F G 无相关
性
B
C G
D
无相关性
溶血反应
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. 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 factors
Surface structures
Enzymes
Exotoxins
Pathogenicity
• Virulence factors
Surface structures
adhesin: LTA
F protein
M protein: anti-phagocytosis
cross-reactive antigen
lipoteichoic acid
F-protein
M protein
fibronectin
epithelial cells
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
O2
Antigenicity
Chemical
Activity
Streptolysin O (SLO)
Streptolysin S (SLS)
oxygen-labile
oxygen-stable
Strong (ASO test)
Weak
Protein
Polypeptide
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
Laboratory diagnosis
specimen
S.aureus
Direct smear
Isolation and cultivation
S.pneumoniae
-hemolytic strep.
PYR test
S. 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,
lancet-shape
• Capsule
– Polysaccharide
– Type-specific antigen
• Fastidious
blood agar
-hemolysis
General properties
• Autolysis
• Bile solubility test: “+”
(-)
(+)
(Bile solubility test)
Pathogenesis
• Virulence factor
• Capsule
• Neuraminidase
• Pneumolysin
• LTA, peptidoglycan
• Main disease
• Pneumonia
• Others: middle ear infections (otitis media),
sinusitis, 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 streptococci
•
•
•
•
•
S.mutans
S.anginosus
S.salivarius
S.mitis
S.sanguis
dental caries
subacute bacterial endocarditis
bile solubility test （－）
optochin sensitivity test（－）
S.agalactiae
• Group B streptococcus, GBS
• Transmission
– vaginal flora
• Disease
– neonatal meningitis
– neonatal pneumonia
– septicemia
S. 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
Pathogenesis
N. gonorrhoeae
N. meningitidis
Virulence Factors
Similar, but –
Differences
in utilization
LOS
IgA1 protease
iron-binding proteins
PILI
Outer Membrane Proteins
(Por,Opa, Rmp proteins)
LOS
Capsule
IgA1 protease
iron-binding proteins
PILI
Outer Membrane Proteins
N. gonorrhoeae /gonococcus
PILI
– Nonpiliated
gonococci not
virulent
– Phase variation
turns pilus
production on/off
– Antigenic variation
N. gonorrhoeae /gonococcus
Outer Membrane Proteins
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]
N. meningitidis/menigococcus
Capsule

13 serotype

A, B, C, Y, W-135
LOS (lipooligosaccharide)
–
–
–
–
–
vascular damage
skin rash
renal failure
shock
disseminated intravascular coagulation (DIC)
Pathogenesis
N. gonorrhoeae
Virulence Factors
N. meningitidis
Similar, but –
Differences
in utilization
LOS
IgA1 protease
LOS
iron-binding proteins
Capsule
PILI
Outer Membrane Proteins
(Por,Opa, Rmp proteins)
X NO capsule
IgA1 protease
iron-binding proteins
PILI
Outer Membrane Proteins
Disease
• Gonorrhea
– Adults
 Transmission: STD (sexually transmitted
disease)
 Clinical disease: Genitourinary tract infection
Male-Urethritis
Female-Urethritis, cervix inflammation
PID (Pelvic Inflammatory Disease)
Sterility
Gonorrhea
Symptomatic infections are notably PURULENT
Urethritis
Disease
• Gonorrhea
– Newborns
Ophthalmia neonatorum
Gonorrhea
Purulent conjunctivitis
Ophthalmia neonatorum
Infection in newborns
during vaginal delivery
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
Treatment ＆Prevention
N. gonorrhoeae
• Antibiotic
• 1%Silver nitrate-- ophthalmia
neonatorum
• No effective vaccine
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
Treatment ＆Prevention
N. gonorrhoeae
• Antibiotic
• 1%Silver nitrate-- ophthalmia
neonatorum
• No effective vaccine
Treatment ＆Prevention
N. meningitidis
• Treatment
penicillin: the first of choice
sulfasulfonamide
• Prevention
immunization: capsule polysaccharide
group B meningitis
Pathogenic cocci/Pyogenic cocci
Staphylococcus aureu
G+ cocci Streptococcus pyogenes
Streptococcus pneumoniae
G-
Neisseria meningitidis
cocci
Neisseria gonorrhoeae
Neisseriae of medical importance
Properties
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