Microbiology I Flashcards
Name 5 ways to identify the presence of a pathogen.
Direct Microbial Analysis Cultivation Antigenic analysis Genetic analysis Detection of Immune response
What are the 4 Direct Detection methods of a pathogen?
Direct (needle in haystack)
Culture (isolated colonies from streaks)
Antigenic (antibodies exquisitely accurate)
Genetic (highly specific, very expensive)
What happens when the highly accurate detection of microbial antigens by antibodies works?
Agglutination
What is an Indirect Detection method for identifying a pathogen?
Measure an immune response
appearance of antibodies against a microbe
What are the 3 broad groups of infectious microbial agents?
Normal flora
Opportunists
Pathogens
What is another term for a pathogen?
Overt or Frank
What are 2 categories of opportunists?
Normal flora
Outsiders
T/F
Viruses can be considered part of the normal flora
False
Diagnostically, pathogens are usually identified through _____ or _____.
Tissue direct assay
Isolation and culture
(both followed by identification)
What antibody is present in an acute infection?
IgM
What is diagnostically relevant for pathogens if Convalescent?
Antibody types an [conc]
Name an acid fast bacteria and two diseases it causes.
Mycobacterium
TB and Leprosy
What does India Ink tell you about a bacteria?
Capsule presence
How is KOH useful in pathogenic determination?
Can confirm if its a Fungus
What type of Direct Visualization involves pre-labeled antibodies that fluoresce?
FITC Serology
An In Vitro culture of bacteria can be grown on what?
Enriched media (augar) Selective media
*Aerobic or Anaerobic
How are viruses cultured?
Eggs or cell culture
What are 2 enzyme tests used in pathogen identification.
Catalase
Oxidase
What are the 3 major life forms found on earth?
Archaea
Bacteria
Eukaryotes
What are the 3 Eucarya genera visible to the naked eye?
Zea, Homo, Coprinus
What are the 5 classes of infectious agents?
Archaea Bacteria Eukaryotes Infectious particles (viruses) Infectious proteins (prions)
What are 3 main classes of Eukaryotic infectious agents?
Helminths (ascaris, enterobius)
Protozoa
Fungi
Name 3 protozoan pathogens.
Plasmodium (malaria)
Giardia (giardiasis)
Toxoplasma
T/F
Archaea are generally not found as human infectious agents.
False
What are 3 places Archaea are found in humans?
Colon
Pulp Chamber
one more? ask around
Name 2 infectious Prions
Mad cow
Kuru
What virus can withstand more environmental stress, enveloped or naked?
Naked
envelopes dry out
T/F
All bacteria have Fimbrae.
True
T/F
Bacteria divide at the same rate as Eukaryotes
False
bacteria fastest - 15 min.
Eukarytoic - around 12 hrs
What bacterial structure makes phagocytosis much more difficult?
Capsules
What is the capsule made out of?
CHO
carbohydrate
T/F
Prokaryotes have no ribosomes
False
but they are much smaller than eukaryotic
What type of Fimbrae binds bacteria to host or other bacteria?
Lectins
What is an important structural component of ECM?
CHO
Describe dsDNA.
Single circular plasmid
T/F
Bacteria can contain several plasmids
True
Size bacterial ribosome:
Size Eukaryotic ribosome:
70S
80S
What is the complex ecological biosystem of bacteria called?
Biofilm
What is a bacterial cell wall made of?
Polysaccharide chains cross-linked by peptides
What are the 2 glucose dimers that make up bacterial cell walls?
N-acetylglucosamine (NAG)
N-acetylmuramic acid (NAM)
What fixes the NAG/NAM/peptide complex to a cell wall in synthesis?
Transpeptidase
these “spot weld”
What is constantly synthesizing and degrading peptidoglycan?
Autolysins
What additional features does Gram Negative bacteria have?
Periplasmic space
Outer membrane
Endotoxin (LPS)
A gram negative can’t hold its alcohol.
explain.
Gram Negative bacteria lose Cresyl Blue when EtOH applied
How many Toll-like receptors are there?
What is the Toll-like receptor that binds LPS?
10
TLS-4
T/F
Toll like receptors are highly specific
False
They are “pattern recognition” so are broadly acting
What cytokine affects Endothelial cells in the LPS > TLS-4 cascade?
TNF
What are the characteristics of systemic LPS pathology?
Intravascular coagulation (blockage) Hypovolemic shock (from decreased BP)
Hypovolemic = Septic
What do macrophages secrete in response to LPS?
Proteases (breakdown ECM and collagen)
PGE-2
TNF
What relaxes pre-capillary sphincters?
substance/cell/cytokine
NO
by Endothelial Cells
signalled by TNF-alpha
*can be activated by LPS > TLR-4
What is PGE-2 effects on bone?
Signals resorption
*Osteoclast activity
What is PAMP and DAMP?
functions?
Pathogen recognition
(aid WBC’s)
Damage recognition
(allow for recognition of damaged cells so PMN’s can remove)
What division of immunity are PAMP and DAMP in?
Native Immunity
What is the most important pro-inflammatory mediator stimulated by Toll-like Receptors?
TNF-alpha
What type of enzyme breaks linkages in starch/glycogen?
Amylase
What type of polysaccharide is structural?
Cellulose
What type of enzyme breaks peptidoglycan?
Lysozyme
*at NAM-NAG linkage
How is Chitin related to Peptidoglycan?
chitin: Beta 1-4 NAG
peptidoglygan: Beta 1-4 NAG-NAM
T/F
ECM is made up of glucose molecules stuck in polymer.
True
Why does penicillin not harm human cells?
It targets peptidoglycan and humans don’t have cell walls
What are the 3 steps of effective penicillin action?
- Bacteria must be growing, using autolysin enzymes called hydrolases
- Blockage of “spot welding” by binding Transpeptidase
- Lysis by osmotic pressure
What would happen if penicillin were added to cells growing in an isotonic solution?
???
Probably wouldn’t burst but would continue to degrade
What type of antibiotics kill bacteria?
What type inhibit their proliferation?
Bacteriocidal
Bacteriostatic
Why does bacteria use right handed D-AA’s in their cell walls?
We digest only L-AA’s
What type of structure is penicilin?
Beta-Lactam Ring
What are 4 methods bacteria have developed to resist Penicillin?
Destroy, Divert, Morph, Stop growing
Penicillin-ase
Pump Penicillin out (outer) membrane
Change shape of Transpeptidase
Decrease Hydrolase Activity
What is a side effect of Penicillin’s unstable Beta-lactam ring?
Can induce immune response by binding self-proteins
(like platelets, RBC’s, macrophage)
*a hypersensitivity
What is a facultative bacteria?
Can Respire (O2, Heme) or Ferment
What is an aerotolerant anaerobe?
What is a microaerophilic anaerobe?
Can tolerate O2 but only ferments
Thrives in low level O2
What is the function of Super Oxide Dismutase?
What is the function of Catalase?
O2- > H2O2
H2O2 > H2O and O2
What 2 enzymes do Obligate aerobes and facultative aerobes have in order to deal with the side effects of Oxygen?
Super Oxide Dismutase
Catalase
Why do strict anaerobes die in the presence of Oxygen?
Don’t have Super Oxide Dismutase or Catalase `