Gram positive coccus (chains or pairs)

Question 1

Important characteristics

Answer 1

• Grows in pairs or chains
• Some species have capsules
• Facultative anaerobes

Classification
Lancefield or hemolytic pattern on blood agar

Hemolytical
*alpha hemolytical (Incomplete hemolysis on blood agar = commential bacteria

• beta hemolysis ( complete hemolysis = pathogens )
• gama hemolyisis ( no change around colony )

Lancefeild is a subdivision for hemolytical streptococcus

Question 2

Streptococcus pneumonia

URT

Answer 2

Metabolism

• Catalase negative
• anaerobic
• alpha hemolytic

Transmission

• A problem in daycare
• Pneumolysis centers
• occurs when bacteria are transported in eustachian tube or bronchi

Pathology

• meningitis
• pneumonia
• sepsis
• otitis media ( middle ear infection )
• Occurs in the upper respiratory tract

Treatment

• Penicillin G (IM)
• Erythromycin
• Ceftriaxone

Virulence

• Polysaccharides ( avoid immune system )
• Cell wall (induces inflammation )
• Autolysis ( lysis cell wall )
• Pneumolysin : (toxic to many host cells and induce inflammation

Question 3

Viridans

Found on teeth

Answer 3

Metabolism

• Catalase neg
• anaerobic
• alpha hemolysis

Location
*human commensals conolizing the oral mucosa, git, and genitourinary tract

Treatment
Penicillin

Pathogenesis

• Found on tooth surfaces , they can cause tooth cavities or they can enter blood during dental procedures and cause endocarditis, embolism, and abscess in various organs including the brain.
• Bacteraemia (rare)

Question 4

Enterococci

Human intestines
doesn’t cause meningitis

Answer 4

Metabolism

• catalase negative
• anaerobe
• alpha,beta ,gamma hemolytical

Pathogenesis

• Urinary infection
• Endocarditis
• Biliary infecyion
• suppurative abdominal lesions
• peritonits

treatment
*Penicillin V and G

Question 5

Pyrogens

Skin and respiratory system

Answer 5

Metabolism
*Lancegroup A
*

Pathogenes

• Associated with human infections
• Causes a wide range of suppurative infections in the respiratory tract and skin
• Causes toxin-mediated diseases
• Some infections are similar to those caused by Staphylococcus aureus

Epidemiology
*Most prevalent of human bacteria

Pathogenesis

• Pharyngitis
• Skin infection (erythematous rash on skin and membrane, cellulitis, necrotizing fascitis = destructive wound infection )
• Toxic shock syndrome
• Bacteremia
• Glomerulonephritis

Treatment
Penicillin V and G
Erythromycin

Question 6

Streptococcus agalactia

neonatal infections + found in throat ,gut

Answer 6

Metabolism 
*beta-hemolytic 
*Lancefield group B
*Catalase negative 
anaerobic 

Pathogenesis

• Neontal meningitis
• neonatal pneumonia
• noenatal absecess

Treatment
Penicillin G