Medical Microbiology (Biology of Small Organisms)

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Medical Microbiology (Biology of Small
Organisms)
Major Topics Included in MAC 221

• Bacteriology
• Virology
• Parasitology
• Mycology
• Immunology

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Introduction To Mac 221

1. Basic Immunology and Host Parasite Relationship
2. Bacteria and Human Diseases caused by bacteria.
3. Parasitology Parasite Human Diseases
4. Virology Virus Human Diseases
5. Mycology Fungi Human Diseases

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Microbiology And The Patient

• Medical Microbiology concerned with
• Aetiology (cause)
• Pathogenesis (Mechanism of production of disease)
• Laboratory Diagnosis
• Treatment of infection
• Epidemiology (spread, distribution, prevalence of
  infection in the community)
• Control and prevention in community

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MIC has Close Link with

1. Pathology
2. Medicine (clinical)
3. Surgery
4. Pharmacology and therapeutics
5. Preventive Medicine

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MIC has a Close Link with Curative Medicine in
regard to

• Precise diagnosis
• Rational treatment of microbial diseases
• Diagnosis of Bacterial infection done by
• Clinical
• Laboratory Methods

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Laboratory Methods Collection of specimens

• Microscopy Stained Specimens
• Unstained Specimens
• Culture
• Identification of the organism
• Tests for Antimicrobial agents serology
• Demonstration of Abs

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Medical Students Need to Know Microbiology
Especially Bacteriology

• To Diagnose
• Bacterial
  infections successfully
• 2) To Treat

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Course Objectives

• Basic understanding of immune system
• 2) Basic understanding of host-parasite
  relationship
• 3) Understandingof the pathogenesis
• 4) Understand the clinical features
• 5) Understand the Epidemiological features

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Course Objectives (Continued)

• 6) Understand the proper use of Clinical Lab.
• a) Specimen collection and handling
• b) Requesting appropriate tests
• c) Interpretation of results of Lab. tests
• Correct selection, use, monitoring of
  anti-microbial therapy
• Understand methods of prevention of infection
  e.g. Vaccine, chemoprophylaxis, hygiene,
  isolation etc.

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Diagram of Atypical Bacterial Cell
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Bacteria

• Unicellular, Microscopic, Prokaryotic Organisms,
  Multiply By Binary Fission.
• Comparison Between Bacteria And Fungi And
  Protozoa
• Bacteria Fungi Protozoa
• Type Prokaryotic Eukaryotic
• Chromosome One Multiple
• (Number)
• Nuclear Absent Present
• Membrane

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Comparison Between Bacteria and Fungi and
Protozoa (Continued)

• Bacteria Fungi Protozoa
• Mitochondria Absent Present
• Ribosomes 70s 80s
• Sterols Absent (Except Usually In
  Mycoplasma) Present
• Cell Wall Rigid Layer Of No Peptido-
• Peptidoglycan Glycan (Absent
  In (In some cases
• Mycoplasma) cellulose
  present)

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Bacteria can be divided into

• Filamentous Bacteria (Actinomycete) Most capable
  of branching
• True (Euobacteria) Divide by Binary Fission
• Spirocheates Divide by Transverse Binary Fission
• Mycoplasma Which Lack Rigid Cell Wall
• Ricketssiae, and Chlamydia which are strict
  Intracellular parasites

Vibrio (coma shape)
Cocci
Bacilli (rods)
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Taxonomic Ranks
Formal Rank Example

• __________________________________________________
  __________________________________________________
  ____________________
• Kingdom Prokaryotae
• Division Gracilicutes
• Class Scotobacteria
• Order Eubacteriales
• Family Enterobacteriae
• Genus Eschirichia, Streptococcus,
  Staphylococcus, Streptococcus, Klebsiella
• Species coli Pyogenes
  aureus pneumoniae pneumonia

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Simplified Classification of Medically
Important Gram-positive Bacteria

• Arranged in Micrococcus
• Aerobes or clusters
• facultative Staphylococcus
• Anaerobes
• Cocci Arranged in Streptococcus
• chains

Anaerobes
Peptostreptococcus
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Simplified Classification of Medically
Important Gram-positive bacteria

• Sporing Bacillus
• Aerobes or facultative
  anaerobes Corynebacterium
• Non- Listeria
• sporing Lactobacillus
• Nocardia
• Mycobacterium
• RODS
• Sporing Clostridium
• Anaerobes
• Non- Actinomycosces
• sporing

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Simplified Classification Of Medically
Important Gram-negative Bacteria

• Aerobes Neisseria
• Cocci
• Anaerobes Veillonella

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Simplified Classification Of Medically
Important Gram-negative Bacteria

• Aerobes Pseudomonas
• Salmonella
• Shigella
• Klebsiella
• Proteus
• Escherichia
• Facultative Yersinia
• Anaerobes
• BACILLI Bordetella
• Haemophilus
• Brucella
• Pasteurella
• Vibrio
• Anaerobes Bacteroids
• Fusobacterium
• Microaerophilic Camplylobacter

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Simplified Classification Of Medically
Important Gram-negative Bacteria

• Aerobes Leptospira
• Spirochaetes
• Anaerobes Borrelia
• Treponema
• Cell wall --- Mycoplasma
• deficient bacteria

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Diagram of Atypical Bacterial Cell
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External Structures

• I) Flagella Long Filaments
• a. Responsible for motility
• b. Protein (Flagellin) similar to myosin
  of muscles
• c. Can be polar, Bipolar or Peritrichous
• Short Filaments
• a. Common pili Adhesion
• b. Sex pili Conjugation

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• Capsule Present in Certain Bacteria.
• Water (2 ) solid Polysaccharide occasionally
  protein
• e.g. Bacillus anthracis
• a. Inhibit Phagocytosis
• b. Antigenic

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Example Of Capsulated Bacteria

• a. Pneumococci
• b. Klebsiella Polysaccharide Capsules
• c. Cl. perfringens
• d. Bacillus anthracis Polypeptide Capsules

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Flagella
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Bacterial Spores

• Hardest part of bacteria
• Contain calicum pectate
• One spore one negative bacteria
• Can live for years
• Example
• 1. Clostidia (Anaerobic)
• e.g. Cl. perfringens
• 2. Bacillus (Aerobic)
• e.g. B. anthracis

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• CELL WALL - porous, permeable to low molecular
  weight (LMW) substances.
• Found in Algae, fungi, plants and bacteria
• Not found in animals
• Functions Of Cell Wall
• a. Confer rigidity upon bacteria
• b. Protects against osmotic pressure which can
  be 5-20 atmospheric pressure in bacteria
• c. Gives bacteria its shape
• d. Participates in cell division
• e. Gram staining characteristic

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Structures of Cell Wall

• Basic mucopeptide (peptidoglycan)
• PEPTIDOGLYCAN consists of
• a. N-acetyl mumaric acid (M)
• b. N-acetyl glucosamine (G) strands.
• Theses strands are linked by peptide side chains
  
• Peptide
• chain

G
M
M
G
G
M
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• In Addition Gram ve bacterial cell wall
• a Thick peptidoglycan layer (many layers)
• b. Teichoic acids (20 of cell wall weight)
• Gram ve cell wall
• a. Thin peptidoglycan layer (1-2 layers)
• b. Out layer of lipopolysaccharide,
  phospholipids, lipoprotein
• c. Porins

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Diagrams Showing The Structure Of Bacterial Cell
Walls
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Annual System

• Bacteriology Immunology
• 50 50 marks
• Practical 10 marks
• Mid term 10 marks
• Final 30 marks
• Parasitology Virology Mycology
• 50 50 marks
• Practical 10 marks
• Mid Term 10 marks
• Final Exam 30 marks