1 Microbes and diseases: what to study-1 • 1. Causative microbe: name, morphology (shape, size, Gram stain, etc.), physiology (aerobe, anaerobe, etc) and some info on classification (what's it related to?) • 2. Pathogenesis and clinical disease: what disease does it cause (signs and symptoms) and how does it do it (capsule, toxins..)? • 3. Transmission and epidemiology: how do you get the disease?
Microbes and diseases: what to study-1. 1. Causative microbe: name, morphology (shape, size, Gram stain, etc.), physiology (aerobe, anaerobe, etc) and some info on classification (what's it related to?) - PowerPoint PPT Presentation
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1Microbes and diseases: what to study-1
• 1. Causative microbe: name, morphology (shape, size, Gram stain, etc.), physiology (aerobe, anaerobe, etc) and some info on classification (what's it related to?)
• 2. Pathogenesis and clinical disease: what disease does it cause (signs and symptoms) and how does it do it (capsule, toxins..)?
• 3. Transmission and epidemiology: how do you get the disease?
2Microbes and diseases: what to study-2
• 4. Diagnosis: How does the lab usually identify the causative agent?
• 5. Treatment: antibiotics prescribed (or not- no cell wall, no penicillin) or other treatment (oral rehydration therapy for cholera).
• 6. Prevention and control (stop the spread; condoms, kill urban rats..)
3Pathogenic Bacteria
• Gram positive rods and cocci– Pyogenic cocci: Staph and Strep– Gram positive rods: Bacillus to Actinomycetes
• Gram negative cocci and bacilli– Gram negative cocci: Neisseria– The Enteric bacteria– Aerobic & Anaerobic Gram negative bacteria
• Miscellaneous pathogens– Mycoplasmas to Helicobacter; Gram -, but odd
4Staphylococcus: G+ coccus
• S. aureus and S. epidermidis (and 21 others).– S. aureus much worse, S. epi an opportunist.– Sturdy, salt tolerant, fac anaerobes; clusters– S. epidermidis common on skin, S. aureus less.
• Diseases of S. aureus– Invasive: skin diseases (rashes, abscesses)
• systemic diseases (bacteremia, organ and bone infections)
• S. pyogenes (“pus-producing”)– M protein and capsule: avoids phagocytosis– Streptokinase, streptolysins for escape & attack– Pyrogenic erythrotoxins (SPEs)
• at least 3 different types• Cause scarlet fever: fever, rash; toxic shock
14Bacillus: G+ rods-2• Bacillus anthracis: cause of anthrax
– Anti-phagocytic capsule of glutamic acid– 3 protein toxin that is lethal– Zoonotic: primarily disease of livestock– Ingestion, inhalation, and cutaneous forms
• Black eschar characteristic of cutaneous form– Not hemolytic; antibiotics, vaccine effective