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Classification of medically important bacteria. 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

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Bacteria
Bacteria

Unicellular, Microscopic, Prokaryotic Organisms, Multiply By Binary Fission.

Comparison Between Bacteria And Fungi And Protozoa

BacteriaFungi & Protozoa

Type Prokaryotic Eukaryotic

Chromosome One Multiple

(Number)

Nuclear Absent Present

Membrane


Comparison Between Bacteria and Fungi and Protozoa (Continued)

BacteriaFungi & 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
Bacteria can be divided into: (Continued)

  • 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)


Taxonomic ranks

Formal Rank Example (Continued)

Taxonomic Ranks

________________________________________________________________________________________________________________________

Kingdom Prokaryotae

Division Gracilicutes

Class Scotobacteria

Order Eubacteriales

Family Enterobacteriae

GenusEschirichia, Streptococcus, Staphylococcus, Streptococcus, Klebsiella

Species coli Pyogenes aureus pneumoniae pneumonia


  • The (Continued)Gram stain, t bacteria into two main groups, is the first step in bacterial classfication & identification. 

  • Bacteria stained purple are Gram + - their cell walls have thick petidoglycan and teichoic acid.

  • Bacteria stained pink are Gram – their cell walls have have thin peptidoglycan and lipopolysaccharides with noteichoic acid.


The Gram stain has four steps: (Continued)

  • 1. crystal violet, the primary stain: followed by

  • 2.gramsiodine, which acts as a mordant by forming a crystal violet-iodine complex, then

  • 3. alcohol, which decolorizes, followed by

  • 4. safranin, the counterstain.


Is this gram stain positive or negative identify the bacteria
Is this gram stain positive or negative? (Continued)Identify the bacteria.


Is this gram stain positive or negative? (Continued)Identify the bacteria.


  • Gram staining tests the bacterial cell wall's ability to retain crystal violet dye during solvent treatment.

    Iodine is added as a mordant to form the crystal violet/iodine complex in order to render the dye impossible to remove.

  • Ethyl-alcohol solvent acts as a decolorizer and dissolves the lipid layer from gram-negative cells. This enhances leaching of the primary stain from the cells into the surrounding solvent.

  • Ethyl-alcohol will dehydrate the thicker gram-positive cell walls, closing the pores as the cell wall shrinks. 

  • For this reason, the diffusion of the crystal violet-iodine staining is inhibited, so the bacteria remain stained. 


Classification based on
Classification based on retain

  • Shape

  • Gram reaction

  • Oxygen

  • Free living & non free living


Simplified classification of medically important gram positive bacteria free living
Simplified Classification of Medically – Important Gram-positive BacteriaFree living

Arranged in Micrococcus

Aerobes or clusters

facultative Staphylococcus

Anaerobes

Cocci Arranged in Streptococcus

chains

Anaerobes

Peptostreptococcus


Simplified classification of medically important gram positive bacteria
Simplified Classification of Medically – Important Gram-positive bacteria

Sporing Bacillus

Aerobes or facultative anaerobes Corynebacterium

Non- Listeria

sporingLactobacillus

Nocardia

Mycobacterium

RODS

Sporing Clostridium

Anaerobes

Non- Actinomycosces

sporing


Simplified classification of medically important gram negative bacteria
Simplified Classification Of Medically – Important Gram-negative Bacteria

Aerobes Neisseria

Cocci

Anaerobes Veillonella


Important gram negative bacteria
Important Gram-negative Bacteria Gram-negative Bacteria

Aerobes Pseudomonas

Salmonella

Shigella

enter Klebsiella

obacProteus

teriae Escherichia

Facultative caeYersinia

Anaerobes

BACILLIrespirleigonellaBordetella

Haemophilus

zoonotBrucella

Pasteurella

francisella

yersinia

Vibrio(curved)

Anaerobes Bacteroids

Fusobacterium

MicroaerophilicCamplylobacter


Simplified classification of medically important gram negative bacteria1
Simplified Classification Of Medically – Important Gram-negative Bacteria

Aerobes Leptospira

Spirochetes Treponema

Anaerobes Borrelia

Cell wall deficient bacteria------- Mycoplasma

2.Non- free living intra cellular— Rickettsia &chlamydia


Capsule Gram-negative Bacteria Present in Certain Bacteria.

  • Polysaccharide;

  • occasionally protein

    e.g.Bacillus anthracis

    importance

    a. Inhibit Phagocytosis

    b. Antigenic


Study template for bacteria
Study template for bacteria Gram-negative Bacteria



Microbiology and the patient
Microbiology And The Patient Gram-negative Bacteria

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


Laboratory methods collection of specimens
Laboratory Methods: Collection of specimens Gram-negative Bacteria

  • Microscopy Stained Specimens

    Unstained Specimens

  • Culture

  • Identification of the organism

  • Tests for Antimicrobial agents serology

  • Demonstration of Abs


6) Understand the proper use of Clinical Lab. Gram-negative Bacteria

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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