Morphology Flashcards
Acid-fast stain
fixation in salin > carbol fuchsin and phenol > 3% HCL and 70% alchohol (Decolorization) > Methylene (counter stain)
if Red (+) if Blue (-)
only for Mycobacterium sp. And Nocardia sp. they have waxes in their cell wall and Resist acid decolorization.
Gram stain
Fixation > crystal violet > iodine treatment > decolonization > counterstain if purple (+) and if pink (-)
Fluorescent stain
primery Antibody binds antigen > secondary anti-antibody with tag binds primary antibody
Most common agars-routine agars
1) blood agar
2) Macconkeys
3) Chocolate
1) 3 posible results
Alpha hemolytic- partial destruction of RBC and release hemoglobin giving the green color.
Beta hemolytic- breaks all blood cells all the way
ex; strep throat
GAMMMA- no hemolysis
2) Inhibits gram (+) only shows gram negative
selects for enterics . Also tells if lactose fermenter pink (e-coli) or notcolorless (Pseudomonas aeruginosa).
3) Fastidious organisms
–Haemophilus influenzae
–Neisseria gonorrhoeae
these the only 2 that grow on chocolate
Special Agar very specific
1)Buffered charcoal yeast
2) Sabouraud Dextrose
3) Lowenstein Jensen
1) Legionella
2) Candida albicans (fungus)
3) Mycobacterium tuberculosis
Bio typing-Hierarchy Classification
Is using biochemical testing to identify certain organisms
Ex: catalase, coagulase, and Indole tests
Catalase test –
Detects presence of catalase enzyme – breaks down peroxide
Used to differentiate btw Streptococci (-) and Staphylococci (+)
Coagulase test
Conversion of fibrinogen to fibrin (gives a solid gel in the test tube) Staphylococcus aureus (+) and Staphylococci (-)
Indole test
Enterics differentiate ecoli (+) from other enteric bacterias
Oxidase test
Tests for presence of enzyme cytochrome oxidase c Pseudomonas aeruginosa (+)
Bacterial Ribosomes
30S + 50S subunits = 70S ribosome
Transcription and translation are coupled
Antibiotics that Inhibition Protein synthesis
ClEST
Tetracycline
Erthyromycin
Chloramphenicol
Streptomycin
Plasmids
Bacterial circular DNA, not needed it to live. Responsible for antimicrobial resistance
More common in gram (-)
Quinolones
Antibiotics inhibiting Bacterial DNA
In gram negative bacteria it inhibits DNA gyrase, unable to pack DNA into cell
-Specific for bacterial DNA gyrase
In gram positive bacteria
-Inhibition of topoisomerase IV
Cytoplasmic Membrane
Made out of a Lipid bilayer
No sterols ( cholesterols with alcohol) Exception - Mycoplasma
Regulates transport
Has Mesosome
-Invagination where DNA binds to replicate
-Segregation of chromosomal DNA into daughter cells
Bacteria lacking cell wall
These bacterias are not visible on gram stain
Mycoplasma-Sterols in membrane
Chlamydia/Chlamydophila-Tissue culture
peptidoglycan
Found in bacterial cell wall Made out of NAG_NAM_NAG_NAM NAG=N-acety glucosomine NAM=N acetyl Muramic Acid Thick in Gram (+) bacteria Its highly polar and hydrophilic, can be digested by lysozyme (bactericidal) in gram (-) bacteria
Penicillin Binding Proteins
Enzymes that cross-link amino acids-(needed for the bacterial cell wall)
Ex: Transpeptidases and Carboxypeptidases
They both are targets for action of penicillins and other beta-lactams
Vancomycin
Blocks D-alanine so it can’t cross link. Vancomycin restart bacteria change the D alanine to D-Lactate
Teichoic acid and Lipoteichoic acid are found in what type of bacteria?
Gram positive
They are used by our immune system to target these bacterias
Lipopolysaccharide (LPS)
Endotoxins found in gram (-) bacteria
Made out of an O antigen, a core, and Lipid A
O antigen
Is exposed to the external environment
Is a liner polysaccharide 50- 100 repeating units each unit has 4-7 sugars
Can be antigenic
LPS Core
The space btw O antigen and Lipid A
Contains unusual sugars
Lipid A
Is the toxic portion of the LPS
It causes septic shock (sepsis)
Outer membrane of bacteria
Only in gram (-)
Has Channels for passive diffusion called porins
Attachment site for -bacteriophage
Inner membrane is similar to membrane of gram-positive organisms
Porins
Are channels for passive diffusion found in the outer membrane of bacteria.
They Restricts entry by size (Important in antimicrobial choice for ex: Vancomycin is too large to enter)
May restrict antiseptics or disinfectants that act on cell memB
However they Permit entry of hydrophilic molecules
Periplasmic space
The space btw the outer cell memB and the peptoglycan wall
It contains degradative enzymes
Enzymes that inactivate antibiotics ex: Beta-lactamase
And “binding proteins”
Beta-lactamase
Numerous (more than 200) enzymes that cleaves beta lactam ring
Ex: -Penicillinases. -Cephalosporinases and
-ESBLs (extended spectrum beta-lactamases)
Mechanisms of beta lactam resistance
Gram (+)
- failure of drug to bind the PBS
- beta-lactamases hydrolyze the drug
Gram (-)
- drug fails to cross outer memB
- failure of drug to bind the PBS
- beta-lactamases hydrolyzes the drug
Lysozme
Bactericidal breaks NAG_NAM bond
Gram + are sensitive
Gram – are resistant (because the outer membrane protects the gram (-))
Capsules
A protective layer (from phagocytosis, environmental changes, dehydration) over the bacteria. Also helps in adherence
Composition varies among species
In most species its made out of polysaccharides
In Anthrax its made out of amino acid
its antigenic, and it’s used in vaccines
Small Capsule-Slime layer/Glycocalyx- causes cavities loosely adherent and non uniform in dinsity or thickness
Encapsulated Organisms
All these cause meningitis in babies Streptococcus pneumoniae Klebsiella pneumoniae Haemophilius influenzae type b Neisseria meningitidis Escherichia coli K1
Biofilm
Bacteria that stick together
In teeth and implants and stuff you put in like catheters.
Major issue for hip implants.
Flagella
- Composed of flagellin (long, hollow helical filaments)
- used for motility, chemotaxis
- Are antigenic
- -Classification – Enterics H antigen
- –E. coli O157:H7
Types of flagella
1- monotrichous (one)
2- amphitrichous (one on each side)
3- iophotrichous (many on one side)
4- peritrichous (many everywhere)
Pili (Fimbriae)
-Pilin proteins
–Common pili – adhesion
–Sex pili – bacterial conjugation
-Virulence factor
-Mostly gram-negatives
-Antigenic variation (thats why we can’t use them in vaccines)
Example
Escherichia coli
Neisseria gonorrhoeae
Females have a lot of UTI and cranberry juice helps
Sporulation
When the bacteria goes through harsh conditions they form spores
The location of the spore maybe used in ID
Only two can form Spores
-Bacillus sp.-Aerobic-Gram-positive rod
-Clostridium sp.-Anaerobic-Gram-positive rod
Anton van Leeuwenhoek
Started the Spontaneous generation debate
found little animalcules
Dr. Jenner
Vaccination
Semmelweis
Childbed fever
Antiseptic use
Oliver Wendell Holmes
Contagious disease
Lister
Antiseptic surgery
Pasteur
Pasteurization Wine Parasitic disease Silkworms Spontaneous generation debunked Attenuation - Rabies vaccine Dogs People - 1885 Pasteur Institute in Paris
Koch
1 organism = 1 disease
ex: Bacillus anthracis causes anthrax
Took pictures of anthrax, tuberculosis organisms
Discovered causes of tuberculosis, cholera, typhoid, diphtheria, tetanus, glanders, lobar pneumonia
won Nobel Prize in Medicine or Physiology 1905
Developed postulates
Koch’s Postulates
a bacterium is Present in every case of disease, absent in healthy organisms
Isolate and grow organism
Inoculate new host and get same disease
Re-isolate same organism from new host
Molecular postulates
Gene or product in virulent strains but not avirulent ones
Disruption of gene disrupts virulence
Introduction of gene into avirulent strain induces virulence
Gene is expressed while in host
Antibodies to gene product are protective
Attenuation
Vaccination – chicken cholera
Pasteur used Koch’s Postulates
Becomes less deadly
Paul Ehrlich
Chemotherapy of Syphilis Treatment – 1910
Researcher in Koch’s lab
Tried 606 compounds
Arsenic derivative
Took to London, Fleming used
Alexander Fleming
discovered Penicillin
Legionella pneumophilia
Legionnaire’s Disease
shows pneumonia
tested by Buffered charcoal yeast
Borrelia burgdorferi
Lyme Disease
Streptococcus pyogenes
Necrotizing fasciitis
Bartonella henselae
cat-scratch disease
and bacillary angiomatosus (in Immuno compromised people)
Klebsiella pneumoniae
mucoidal growth – encapsulated
Pseudomonas aeruginosa
Gram (-)
Oxidase test (+)
Green color
Fruity Grape oder
Mycoplasma
Lack a cell wall
Can not gram stain
Sterols are found in cytoplasmic membrane
Mycobacterium
Doesn't gram stain Need acid fast staining Cell wall has waxes Pigmented growth Mycobacterium tuberculosis can grow on a special ager Lowenstein Jensen
Proteus
Swarming
Bacillus sp.
Aerobic
Gram-positive rod
Forms spores
Clostridium sp.
Anaerobic
Gram-positive rod
Can form spores
