Post on 04-Jan-2016
Pathogenic and Pathogenic and opportunistic cocci. opportunistic cocci.
Classification, biological Classification, biological properties. Staphylococci, properties. Staphylococci,
streptococci, gonococci and streptococci, gonococci and meningococci.meningococci.
StaphylococcusStaphylococcusClassification
• Family – Micrococcaceae• Genus – Staphylococcus• Species:1. S. aureus 2. S. epidermidis3. S. saprophyticus
Staphylococci in the pure Staphylococci in the pure culture and in the pus smearsculture and in the pus smears
CultureCulture• They grow readily on ordinary
culture media• The optimal temperature being
370C and pH 7,4-7,6• They are aerobes and facultative
anaerobes• Culture media: nutrient agar,
blood agar, salt media
Differentiation of the S.aureus Differentiation of the S.aureus from opportunistsfrom opportunists
Hemolysis appearance on the blood agar DNAase activity (on the top)
Differentiation of the staphylococciDifferentiation of the staphylococci
Coagulase activity (test is positive for S.aureus)
Novobiocin disk test to differentiate S.saprophyticus (left) and S.epidermidis (right)
PathogenesisPathogenesis• Staphylococcal diseases may be
classified as 1. Cutaneous infections 2. Deep infections3. Food poisoning4. Nosocomial infections (hospital
infections)5. Skin exfoliative disease
(staphylococcal scalded skin syndrome)
6. Toxic shock syndrome
Laboratory diagnosisLaboratory diagnosis• Direct microscopy• Culture.
The characteristics help to The characteristics help to distinguish the pathogenic strains distinguish the pathogenic strains
from non-pathogenic strainsfrom non-pathogenic strains
• Beta type of haemolysis on blood agar• Production of a golden yellow pigment• Coagulase production• Mannitol fermentation• Gelatin liquefaction• Phosphatase production• Production of enzyme deoxyribonuclease• Tellurite reduction
ProphylaxisProphylaxis• General prophylaxis.
Staphylococcus aureusStaphylococcus aureus
StreptococcusStreptococcusClassifications:
A. Due to type of hemolysisB. Lancefield´s classification (serological)C. Due to phylogenetic relationship
Different types of hemolysisDifferent types of hemolysis
Α -Hemolysis
Β-Hemolysis
Γ-Hemolysis
S.pyogenes (smears from S.pyogenes (smears from the agar culture(on the left) and the agar culture(on the left) and
sugar broth (on the right) sugar broth (on the right)
S.pneumoniae (smears from the S.pneumoniae (smears from the pure culture and from the sputum)pure culture and from the sputum)
CultureCulture• aerobes and facultative anaerobes• media containing blood, serum or sugars.
•
Laboratory diagnosisLaboratory diagnosis• Suppurative infections :
microscopy and pure culture isolation
• Non-suppurative sequelae: serology
Streptococcus pyogenesStreptococcus pyogenes
NeisseriaNeisseria• Classification
• Family - Neisseriaceae• Genus – Neisseria• Species:1.N. meningitidis 2.N. gonorrhoeae
N. meningitidis in the smears from N. meningitidis in the smears from the pure culture and clinical samplethe pure culture and clinical sample
CultureCulture• They are strict aerobes.• The optimum temperature and pH
for growth are 35-360C and 7,4-7,6 respectively.
• Growth occurs in media enriched with blood, serum or ascitic fluid.
Antigenic classificationAntigenic classification
•N. meningitidis has been divided into 13 serogroups
Laboratory diagnosisLaboratory diagnosis• Direct microscopy • Antigen detection • Culture. • Serology • Polymerase chain reaction.
ProphylaxisProphylaxis•Chemoprophylaxis• Immunoprophylaxis.
Neisseria meningitidisNeisseria meningitidis
N. gonorrhoeaeN. gonorrhoeae
Laboratory diagnosisLaboratory diagnosis
• Direct microscopy.• Culture.• Serology