Gram positive bacterias

For yadanar

Genus Staphylococcus (Morphology and identification)

Gram-positive spherical cells arranged in

grapelike irregular clusters

Test that differentiates the staphylococci from the

streptococci.

Catalase test

Test that differentiates Staphylococcus aureus from Staph.

epidermidis and Staph. saprophyticus.

Coagulate test

Staphylococci virulence factors (Enzymes)

i) Catalase converts hydrogen peroxide into water and oxygen.

ii) Coagulase triggers blood plasma clotting, allowing bacteria protection

from immune defenses.

iii) Streptokinase dissolves blood clots. Bacteria trapped within a clot can

free themselves and spread the infection

iv) Hyaluronidase dissolves the ”cement“ that holds together the

cells that line the intestinal tract, then invade deeper cells within

the intestinal tissues

Staphylococci virulence factors (Toxins)

v) Exotoxins

- α, β, δ and γ toxins lysing white blood cells, necrosis and

severe inflammation

vi) Panton-Valentine leukocidin:

• acts on the white blood cell membrane.

vii) Exfoliative Toxins

# Epidermolytic toxin A and B cause generalized

desquamation of the epidermis.

viii) Toxic Shock Syndrome Toxin

 It is associated with fever, desquamative skin rash, shock and

multisystem involvement.

ix) Enterotoxins

(A–E, G–J, K–R and U, V)

 an important cause of food poisoning

Infections caused by Staphylococcus aureus

Toxin associated diseases caused by Staphylococcus aureus

Scalded skin syndrome

Bullous exfoliation

Toxic shock syndrome

Food poisoning

Staph. epidermidis normal flora and related infections

the normal flora of the human skin respiratory and gastrointestinal tracts.

may infect orthopedic or cardiovascular prostheses or cause disease in immunosuppressed persons.

Staph. saprophyticus related infections

urinary tract infections in young women

Genus streptococcus classification

Genus streptococcus virulence factors

Infections caused by Streptococcus pyogenes (Cutaneous evasion)

Streptococcus pyogenes local infection

Streptococcal sore throat (pharyngitis)

Streptococcal pyoderma (impetigo)

Streptococcus pyogenes invasion

1) Streptococcal toxic shock syndrome

2) Scarlet fever

Streptococcus pyogenes (Post streptococcal diseases)

Viridans streptococci and their normal flora and related infections

normal flora of the upper respiratory tract

may reach the bloodstream as a result of trauma and are a principal cause of endocarditis on abnormal heart valves.

Strep. mutans contributes to the genesis of dental caries.

Streptococcus pneumoniae and its infections

Pneumococcal pneumonia

Bacteremia from pneumonia can cause meningitis endocarditis and septic arthritis

Streptococcus agalactiae and its infections and normal flora

part of the normal vaginal flora in 5-25% of women.

neonatal sepsis, meningitis or respiratory distress syndrome.

bacteremia, skin and soft tissue infections, respiratory infections and genitourinary infections in adults.

Enterococci and their infections and normal flora

Bacillus anthracis and anthrax mode of transmission

Bacillus anthracis and anthrax virulence factors

Depends on the portal of entry three types of anthrax

Cutaneous anthrax

GI anthrax

Pulmonary anthrax

Cutaneous anthrax

Entry of spores (exposed areas of arms and hands or injured skin)

Pruritic papule- vesicle-necrotic ulcer- edema-eschar

Lymphangitis and lymphadenopathy and systemic signs and symptoms of fever, malaise and headache may occur.

May lead to sepsis

Pulmonary anthrax (inhalation anthrax)

Substernal pain

Haemorrhagic pleura effusion

Sepsis

Potent toxin - can be use in biologic warfare

GI anthrax

Lab diagnosis of anthrax

Bacillus cereus related infection

Corynebacterium diphtheriae Morphology and identification

Gram positive club-shaped bacilli arranged in Chinese

letter appearance.

Corynebacterium diphtheriae culture characters

Corynebacterium diphtheriae virulence factors and clinical features

Virulence factors -bacteria establishment in the throat.

Production of exotoxin (diphtheria toxin)

(necrotizing and neurotoxic effects)

Corynebacterium diphtheriae toxin complication

Clostridium tetani morphology and source

Gram positive bacillus with terminal round spores (drum stick appearance)

Commonly found in soil, hospitals and intestines of man and animal

Clostridium tetani virulence factors

Clostridium tetani mode of transmission and clinical features

Clostridium tetani lab diagnosis treatment and prevention

Tetanus neonatorum

From infected umbilical cord