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