Lesion caused and Laboratory diagnosis of streptococcus

Lesion caused and Laboratory diagnosis of streptococcus

Lesion or disease caused by streptococcus:

1. Suppurative:

Respiratory tract	ð  Sore throat ð  Tonsillitis ð  Pharyngitis ð  Peritonsillar abscess.
Skin &soft tissue	ð  Impetigo ð  Erysipelas ð  Cellulitis.
Genital tract	ðPuerperal sepsis
Ear infection	ð  Otitis media ð  Mastoiditis
Deep infection	ð  Acute endocarditic ð  Lymphadenopathy ð  Septicaemia

1. Not –Superlative:

1. Rheumatic fever (following throat infection)
2. Acute glomerulonephritis(following skin infection)

Laboratory diagnosis of streptococcus:

Diagnosis is based on demonstration of causative agent by microscopic examination and isolation and identification by standard bacteriological techniques from cutrue,Biochemical tests are also helpful.

1. Speeimen: Depends according to site of infection, such as-

2. Microscopic examination:

By Gram staining-

Findings : Gram –positive cocci arranged in chain (Long chain or short chain)

3. Isolation and identification from culture:Culture is done in blood agar media.Findings : Pin –point colony surrounded by a clear zone of hemolysis.Culture is also done in chocolate agar media.

4. Biochemical test:
   
   (a)    Cataloes test-negative(b)   Coagulates test-negative

5. Serological test:
   
   (a)    ASO (anti –streptomycin-O)titer.(b)   Anti-diphosphopyridine nucleotidase(anti DPN ase)(c)    Anti-DNase –B(d)   Anti –streptokinase antibody.