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