Medical Microbiology (Biology of Small Organisms) Major Topics Included in MAC 221 Bacteriology Virology Parasitology Mycology Immunology

Introduction To Mac 221: Basic Immunology and Host Parasite Relationship Bacteria and Human Diseases caused by bacteria. Parasitology Parasite & Human Diseases Virology – Virus & Human Diseases Mycology – Fungi & Human Diseases

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

MIC has Close Link with: Pathology Medicine (clinical) Surgery Pharmacology and therapeutics Preventive Medicine

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

Laboratory Methods: Collection of specimens Microscopy Stained Specimens Unstained Specimens Culture Identification of the organism Tests for Antimicrobial agents serology Demonstration of Abs

Medical Students Need to Know Microbiology Especially Bacteriology To Diagnose Bacterial infections successfully 2) To Treat

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

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.

Diagram of Atypical Bacterial Cell

Comparison Between Bacteria And Fungi And Protozoa 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

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)

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 Cocci Bacilli (rods) Vibrio (coma shape)

Taxonomic Ranks Formal Rank Example Kingdom Prokaryotae ________________________________________________________________________________________________________________________ Kingdom Prokaryotae Division Gracilicutes Class Scotobacteria Order Eubacteriales Family Enterobacteriae Genus Eschirichia, Streptococcus, Staphylococcus, Streptococcus, Klebsiella Species coli Pyogenes aureus pneumoniae pneumonia

Arranged in Micrococcus Simplified Classification of Medically – Important Gram-positive Bacteria Arranged in Micrococcus Aerobes or clusters facultative Staphylococcus Anaerobes Cocci Arranged in Streptococcus chains Anaerobes Peptostreptococcus

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

Simplified Classification Of Medically – Important Gram-negative Bacteria Aerobes Neisseria Cocci Anaerobes Veillonella

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

Simplified Classification Of Medically – Important Gram-negative Bacteria Aerobes Leptospira Spirochaetes Anaerobes Borrelia Treponema Cell wall --- Mycoplasma deficient bacteria

Diagram of Atypical Bacterial Cell

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

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

Example Of Capsulated Bacteria a. Pneumococci b. Klebsiella Polysaccharide Capsules c. Cl. perfringens d. Bacillus anthracis Polypeptide Capsules

Flagella

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

a. Confer rigidity upon bacteria 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

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

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

Diagrams Showing The Structure Of Bacterial Cell Walls

Annual System Bacteriology + Immunology = 50% = 50 marks Practical = 10 marks Mid term = 10 marks Final = 30 marks Parasitology & Virology + Mycology = 50% = 50 marks Mid Term = 10 marks Final Exam= 30 marks