Under the Sea Flashcards
6 steps of infectious disease process
1) encounter
2) entry
3) spread
4) multiplication
5) damage
6) outcome
2 different processes of entry into a host
1) inhalation or ingestion (body cavities that are contiguous with outside)
2) penetration of microorganisms into deeper tissues after crossing the epithelial barrier (insect bites, cuts and wounds, organ transplants, blood transfusions)
Not considered inside the body
Nose, Mouth, Respiratory Tract, Alimentary Canal, Anus, Female Genital Tract, Urinary Tract
Penetration of bacteria into epithelial cells involves 2 steps:
1) attachment to specific receptors
2) internalization
Spread of infection has 2 meanings:
1) lateral propagation to contiguous tissues
2) dissemination to distant sites
Microbes must overcome ______ to multiply and spread
host defenses
______ is important in establishing an infection (varies with different organisms)
Inoculum size
4 possible outcomes of a host-parasite interaction
1) host wins out and clears infection
2) parasite overcomes host
3) host and parasite adapt to each other
4) Neither host or parasite win (chronic infection can continue indefinitely)
Damage to host can be caused by _______ or by _______ or both.
the infectious agent or by host response
Great majority of microorganisms are _________. They coexist without causing harm. It can be difficult to identify a bacterium as such.
commensal.
Gram positive bacteria have a thick cell wall made up of _____, which is a ________.
murein, peptidoglycan
Murein is made up of long chains of ____________ and ___________ linked together by short polypeptides.
N-acetylmuramic acid and N-acetylglucosamine
Gram negative bacteria have a ______ of ______ between two membranes (lipid bilayers).
thin layer, murein
Outside of the outer membrane of gram negative bacteria is made up of ______ that is different for different bacteria.
Lipopolysaccharaide (LPS).
LPS is a toxic ____, even in its purified form
Endotoxin.
LPS is made up of a ____ region that faces into the membrane and a ____________ region face out
lipid; polysaccharide
The outer _________ region of LPS is highly variable and antigenic.
O-antigen
Bactericidal agents ______ bacteria; bacteriostatic agent _______.
kill; inhibit growth
_______ and other ________ are antibiotics that affect the cell wall. They are bactericidal
Penicilins and beta-lactams
Antibiotics often work by targeting bacterial _________
ribosomes
There are 2 subunits to bacterial ribosomes ____ and _____ subunit
30S and 50S
30S subunit is primarily responsible for
translation of mRNA
50S subunit is primarily responsible for
joining amino acids together and moving the complex along the mRNA molecule
Antibiotics can target either ______ & _______ subunit
30S and 50S
_______ & _________ inhibit folic and metabolism
sulfonamides & trimethoprim
These inhibit protein synthesis (3)
Aminoglycosides, tetracyclines, and erythromycin
2 examples of Aminoglycosides..
streptomycin and kanamycin
Metronidazole inhibits _____________
DNA synthesis
______ are specialized structures on the surface of bacteria that that are involved in adhesion to cells or other surfaces.
Pili (fimbriae)
Specialized pili that link a donor cell to a recipient cell during DNA transfer
Sex pili
Surface structures used for locomotion
Flagella
Flagella cause movement when they rotate ________ and _______ when they rotate __________
counterclockwise; tumbling; clockwise
Flagellar movement is used by bacteria for ________
chemotaxis
The movement towards substances that attract and away from substances that repel
chemotaxis
________ must have oxygen to grow
Strict aerobes
________ cannot tolerate oxygen and _________ can grow with or without O2.
Strict aerobes; facultative anaerobes
_____ _______ parasites can only grow inside host cells.
Obligate intracellular
Ratio between effective and toxic dose of an antibiotic
therapeutic index
4 Methods for antibiotic resistance by bacteria
1) enzymes that inactivate the drug
2) inhibit uptake of the drug
3) increase secretion of the drug (pump it out of cell)
4) Modify target of drug
Drug resistant genes are often found on ________ that can be transferred from one bacteria to another
plasmids
Bacteria must (3 things) to survive as an infectious agent
1) avoid being washed away
2) find a nutritionally compatible niche
3) survive host defenses
4) transfer to a new host
Damage to a host as a result of infection can be caused by
1) cell death
2) pharmacological alterations of metabolism
3) survive host defenses
4) transfer to a new host
Many structures on the microbial surface consists of repeated molecules, known as..
pathogen associated molecular patterns
________ recognize pathogen associated molecular patterns
Pattern recognition receptors
Bacteria often classified via their surface antigens (serotype)
a) O refers to..
b) H refers to..
c) K refers to..
a) LPS
b) flagella
c) capsule
