Pyogenic cocci

Marut LaohavirojMD, PhD

Department of Microbiology,

Faculty of Medicine, KKU

Outline

-Bacterial identification -Clinical signs and symptoms-General characteristic -Treatment-Pathogenesis

Streptococci Pathogenic NeisseriaStaphylococci

4

Pyogenic cocci

• Gram positive cocci

Staphylococcus spp.

S. aureus, S. epidermidis, S. saprophyticus

Streptococcus spp.

S. pyogenes, S. agalactiae, S. pneumoniae, Viridans streptococci Enterococcus spp.

• Gram negative cocci

Neisseria spp.

N. gonorrhoeae, N. meningitidis

Catalase test

Gram-positive cocci

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(-)

Staphylococci

Coagulase test Fibrinogen Fibrin(plasma) (clot)

Co

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Staphylococci test

Coagulase

leukocyte destruction and tissue necrosis

Virulence factors S.aureus

Virulence factors S.aureus

1. Cell Surface Factors

Teichoic acid promoting adherence, antigenic determinant.

Protein A binds Fc portion of IgG

Fibronectin-binding Proteins

2. Secreted Factors:

Superantigens: Enterotoxins, TSST-1,

alpha-toxin (dermonecrotic)

3. Cytolysins : hemolysin, leukocidin family (PVL)

(Panton-Valentine leucocidin)

4. Enzyme: Lipase, DNAse, Penicillinase, hyaluronidase,

Proteases (Exfoliative toxin, epidermolytic toxin, (ETA &ETB))

Folliculitis Furuncle/Boilspainful nodule

Carbuncle (ฝฝกบว)

Staphylococcal scalded skin syndrome (SSSS): Exfoliative toxin causes blisters

CLINICAL MANIFESTATIONS

Skin and soft tissue infection

• Impetigo (infection of the epidermis)

• Folliculitis (infection of the superficial dermis)

• Furuncles, carbuncles, and abscess (infection of the deep dermis)

• Hidradenitis suppurativa (follicular infection of intertriginous areas)

• Cellulitis, erysipelas, and fasciitis (infection of the subcutaneous tissues)

• Pyomyositis (infection of skeletal muscle)

• Mastitis

• Surgical site infections

CLINICAL MANIFESTATIONS

Bacteremia

Infective endocarditis — S. aureus is the most common cause of infective endocarditis (IE)

• Risk factors for IE in the setting of S. aureus bacteremia:

• Prosthetic heart valve (incidence up to 50 percent)

• Predisposing cardiac abnormalities

• Injection drug use (IVDU)

• Intravascular catheter infection

Bacteremic spread and endocarditis are most common in drug abusers

Staphylococcus aureus

เกาะตด

Staphylococcus epidermidis

• Coagulase negative, normal skin flora

• The ability to form biofilms on devices is a major virulence factor

• Risk: Catheters• Prosthetics• Shunts• IV needles

• Prosthetic valve endocarditis; Prosthetic joint.

• Strains of S. epidermidis that produce a glycocalyx are more likely to adhere to prosthetic implant materials

Important Features of Pathogenesis by Staphylococci

Organism Type of Pathogenesis Typical Disease Predisposing Factor Mode of Prevention

S. aureus 1. Toxigenic (superantigen)

Toxic shock syndrome Vaginal or nasal tampons Reduce time of tampon use

Food poisoning Improper food storage Refrigerate food

2. Pyogenic (abscess)

a. Local Skin infection (e.g., impetigo, surgical-wound infections)

Poor skin hygiene; failure to follow aseptic procedures

Cleanliness; handwashing; reduce nasal carriage

b. Disseminated Sepsis, endocarditis IV drug use Reduce IV drug use

S. epidermidis Pyogenic Infections of intravenous catheter sites and prosthetic devices

Failure to follow aseptic procedures or remove IV catheters promptly

Handwashing; remove IV catheters promptly

S. saprophyticus Pyogenic Urinary tract infection Sexual activity

(Review of Medical Microbiology & Immunology: A Guide to Clinical Infectious Diseases, 15e)

Streptococci

Streptococci spp.Gram positive cocci, Chain /diploccocci - Normal flora in throat, intestine

•Brown’s classification (Hemolytic activity)

• Lancefield grouping(Serology)

Complete hemolysis Partial hemolysis Non-hemolysisS. pyogenes

/Beta-streptococcus gr. A (GABS) (GAS)S. agalactiae

/Beta-streptococcus gr. B (GBS)

S. pneumoniae

Viridans streptococci

Enterococcus faecalis

Enterococcus faecium

S.bovis

20 serologic classification A-V

Ex.

Beta-hemolysis• Group A streptococci (S. pyogenes) ( GAS),

( Streptococcal pharyngitis; Strep sore throat.)

Bacitracin sensitivity test-ใชแยก gr.A

กอโรคไดทกระบบ โดยเฉพาะ URI

• Group B streptococci (S. agalactiae)(GBS):

อยในชองคลอด กอโรคในเดกแรกเกด

Streptococcus pyogenes (GABS)Gram-positive cocci in chain

(SPE, erythrogenic toxin) >> Scarlet fever, toxic shock syndrome

Streptodornase (DNAase): degrade DNA

Virulence factors

1.Cell surface• Protein M: Adhesion, สลาย C3b, antiphagocytosis,

• Capsule antiphagocytosis,• Pili

2. Enzymes• Hyaluronidase

• Fibrinolysin ( Streptokinase)

• DNAse : anti-DNAse B• Amylase

Virulence factors

3. Toxins

• Streptococcal pyrogenic exotoxins (SPE)/ Erythrogenic toxin:

Scarlet fever

• Septicemia -Toxic shock like syndrome

• Streptolysin (hemolysin)

• Streptolysin O : Anti-streptolysin O (ASO- titer)

Streptolysin S

doughnut sign in acute streptococcal pharyngitis

Streptococcal sore thorat Epstein–Barr virus (EBV)

Peritonsillar Abscess

Scarlet fever

Sand paper like rash Circumoral pallor

Desquamation

Pastia's line

Strawberry tongue

Erythrogenic toxin

Erysipelas (ไฟลามทง)ตดเชอใน epidermis และ lymphatic tract/ GABS

Complication from Streptococcal infection

1. Acute rheumatic fever

2. Acute Post Streptococcal Glomerulonephritis( APSGN)

Hypertension

3. Necrotizing fasciitis

Streptococcus pyogenes

Group B Streptococci : GBS:(S. agalactiae)

• Polysaccharide capsule• Sialic acid in capsule inhibit

alternative compliment and neutrophil activity)

GBS: ascending infection in pregnant women

Early onset infection in neonate (7 days)

Gram positive diplococci lancet shape

Streptococcus pneumoniae

Optochin disc

Virulence factor: Capsule

Tx: Penicillin

Quellung reaction; Antisera directed against the capsular polysaccharide.

CbpA: Choline-binding proteins; adhesin/ invasion/ evasionPneumococcal surface proteins A and C (PspA and PspC),: adhesin

invasion/ evasion

Cytotoxic

Opsonization

• S. mutans, S.mitis, S.sanguis

• Resident oral microbiota of humans

• Subacute bacterial endocarditis (SBE)

• Tx: Penicillin

Viridans group streptococci

g- hemolysis : non-hemolysis

Gr. D streptococci/ enterococci• Enterococcus faecalis

• Enterococcus faecium

• อยในล ำไส

• Nosocomial infection, UTI, endocarditis, sepsis

• Drug resistant: Pen, Ceph, Aminoglycoside

• Drug of choice : Ampicilin / vancomycin/ BL-BI

Enterococcus spp.

Gram positive cocci short chain Non hemolysis

Capsule: OpsonizationDRSP: Drug resistant S. pneumoniae

ATB spectrum

Neisseria spp.

Neisseria spp.

Gram negative diplococci kidney shape

1. Pathogenic Neisseria

-N.gonorrhoeae

-N.meningitidis

2.Non- Pathogenic Neisseria

- Normal flora

Oxidase test

Detects the presence of a cytochrome oxidase system that will catalysethe transport of electrons between electron donors in the bacteria and a redox dye- tetramethyl-p-phenylene-diamine.

Neisseria gonorrhoreae

• Grow on chocolate agar, and incubated in a moist environment at 37ºC under an atmosphere of 3 –10% CO2

Virulence factors

• Pili >adherence: N.g, N.m

• Capsule> antiphagocytosis : N.m

• Endotoxin : N.m

• IgA1 protease N.g

• Outer membrane protein (OMP)>

• Adhesion &invasion

• Iron - binding protein

Neisseria meningitidis

• Meningococcemia

• Hemorrhagic rash ( purpura fulminans ) with DIC ( disseminated intravascular coagulation)

• Waterhouse-Friderichsen syndrome (Adrenal gland failure due to hemorrhage)

• Meningitis

• Nasopharynx ของพาหะ ปกต 2-8%

• พบในบรเวณทคนแออด

• ผปวย 50% ต ากวา 5 ขวบ

• Virulent factors• Capsule, pili, endotoxin, OMP

community-acquired bacterial meningitis in both children and adults

Purpura fulminans

Neisseria spp.

Moraxella catarrhalis ?

Contacted case?