Medically important cocci
Pyogenic bacteria
• Staphylococcus (family Micrococcaceae)
• Streptococcus (family Streptococcaceae)
• Neisseria (family Neisseriaceae)
Staphylococci
• Skin and mucous membrane
• Pathogen for human and animals
• Gram positive cocci
• Facultative aero-anaerobi
• Appearing in clusters, short chains anddiplococci
• Lack flagella and spore
• Some contains capsule
StaphylococciI. Generals: 30 species
– S.saprophyticus
– S.epidermidis( S.slbus)
= Staphylococcus aureus
Staphylococcus aureus
• Spherical 1µ
• In clusters after cultivation on solid media
cultivation
• 37 0C ( 10-46 0C )
• Aero-anaerobic ( O2 and CO2)
• NaCl (7.5-10%)
• Heat (600C to 1h)
• Antibiotics and antiseptics
Enzymes of S.aureus
• Coagulase (97%)
• Hyaluronidase (spreading factor)
• Fibrinolysine (35%)
• DNAase
• Lipase
• Catalase
• Penicillinase (more than 75%)
Toxins of S.aureus
• Hemolysins (α- Hemolysine , β hemolysine, δ hemolysine , γ hemolysine )
• Leukucidin
• Enterotoxin (A-F) 50%S.aureus (resist to boiling for 30min)
• Exfoliative toxin (SSSS)
• TSST
Pathogenicity
A. Staphylococcus aureus
A.1 Localized infections
– Cutaneous (folliculitis, furuncle, impetigo,carbuncle,blepharitis, panaris)
– ORL (sinusite, otitis, Pneumonia)
– Septicemia ,osteomyelitis,endocarditis,polyarthritis,meningitis, toxemia
A.2 Toxic infections
– Toxic shock syndrom– SSSS(staphylococcal scalded skin syndrom)– Food intoxication (1-8h) vomiting ,diarrhea, nausea, self limited
Site of pathogenicity
abcès
folliculitis
furuncle
Abcess
folliculitis
Osteomyelitis
Chronic osteomyelitis
STAPHYLOCOCCICTOXINFECTIONS
I. STAPHYLOCOCCAL SCALDED SKIN SYNDROME
– (SSSS)– : S. aureus produce exfoliative toxin– Fever– Generalised eruptions (cutaneous + mucous)
Scarlatine staphylococcique
Toxic shock
Impétigo bulleux
SSSS
Impétigo
Non supurative infetions of toxic origin
SSSS
Impétigo bulleux
EXFOLIATINE
Staphylococcus aureusPathogenicity
SSSS
STAPHYLOCOCCIC TOXEMIA
• III - Staphylococcal toxic shock syndrom
– 5-10 % mortality
– TSST-1
– 20-30 % portal of entry vaginal
– Character hyper-absorbant to certain tampons.
staphylococcal toxic shock
– Staphylococcal toxic shock syndrome
• High fever
• hypotension
• Profound cutaneous nodules
• Myalgia
• Cardiac and tubular complications
• S.aureus TSST1
B. Other staphylococci( coagulase negative
Staphylococcus epidermidis, S.saprophyticus S. capitis …..Opportunistic and nosocomial ( immunocompromised patients)
S.epidermidis: skin, hair follicules and mucous membrane (UTI,Endocardits, Bacteremia)
S.saprophyticus: skin, intestine and vagina( esp UTI)
Mode of transmission:-surgery-catheter-Instruments_truama
Direct biologic diagnosis
– Gram staining
– Gram positive cocci
Catalase + (differentiate from strept)
Direct biologic diagnosis
Identification Aspect of colonies Coagulase
S. aureus golden Positive
S. albus white Négative
S.Saprophyticus Variable
– ANTIBIOGRAMME
Color of colonies Golden white Vulnerable
Anaerobic + - -
Aerobic + w w
Manitol fermentation + - w*
sensitive to lysostaphin + - -
sensitive to novobiocin + + -
β- hemolysis(α-toxin) + - -
Coagulase+ - -
Test S.aures S. epdermidis S.saprophyticus
تجرید انواع استافیلوکوک ھای عمده ازنگاه کلینیکی
* Weak
Treatment
• Multidrug resistant
• Penicilline, Gentamicine, Tetracycline, Methicilin,Quinolones, Erythromycine, Sulfamides, Cephalosporines, Rifampicin
Epidemiology
• Main reservoir are human and abcess
• Careful hygiene and adequate cleansing of surgical incisions and burns
• Isolation of people with open lesions
• Handwashing, proper disposal of infectious dressings and discharges.