Common bacterial infections Flashcards
This level of immunity is non-specific ie. has no memory
innate immunity
Types of innate immunity
Physical barrier
Phagocytic cells
Physical barrier criteria
a. Intact skin
b. Mucous membranes eg. Respiratory tract
c. Blood-brain barrier- tight junctions inhibit entry of organisms
via uninflamed tissues
Phagocytic cells criteria
a. Macrophages, Neutrophils, Natural killer cells
b. These cells produce proinflammatory cytokines. Eg. TNF,
IL-1, IL-6
c. Acute phase reactants are produced- eg. CRP
Types of adaptive immunity
Active and passive
Active vs. passive immunity
Passive immunity- preformed antibodies eg. Breast milk, serum globulin
Active immunity- exposure to an organism via direct exposure or a vaccine
B-cells and T-cell funtions
i. B cells produce antibodies- neutralize toxins, lyse bacteria, opsonization of bacteria
ii. T cells- cytotoxic destruction, activates macrophages, help B cells produce antibodies
Pathogenic vs. Opportunistic organisms
Pathogenic organism: Those in which cause disease
Opportunistic pathogen: Might cause disease if the conditions are right
Eg. Immunocompromised
What is a carrier state?
a person may have an asymptomatic infection, but serve as a reservoir for an infectious organism given to other individuals
Mycoplasma have ____, so cannot be classified with a gram stain
no cell wall
If bacteria do not have these enzymes, they cannot live in oxygen
superoxide dismutase, peroxidase, and catalase
_____ is used in the absence of oxygen to produce ATP.
Fermentation
T/F Bacterial species vary in the amounts of oxygen they are able to tolerate
T
_____- require oxygen to
grow, and uses the Krebs cycle
Obligate aerobes
______- aerobic bacteria that use oxygen if present, but use fermentation if oxygen is not present
Facultative anaerobes
_____- thrives in an environment with low oxygen
Microaerophilic
______- unable to grow in
the presence of oxygen
Obligate anaerobe
_____ - Chlamydia and Rickettsia lack ability to produce ATP
Obligate intracellular
Characteristic symptoms of an anaerobic bacteria infection
Foul smelling discharge
Gas in the tissue
Necrotic Tissue
Bacteria structure
● unicellular prokaryotic cells measuring about 0.2 to 5 µm.
● Lack a nucleus- single circular DNA strand called a nucleoid
● 70S ribosomes
● Bacterial ribosomes contain a 50S and 30S subunit
● Human cells have 80S ribosomes made up of 60S and 40S subunits
● Lack organelles (eg. Absent mitochondria)
● Cell wall (eg. Human cells have no cell wall)
● May contain plasmids
● Some are motile by means of their flagella
● Some bacteria are spore forming
The lipopolysaccharide (LPS) layer of gram negative bacteria is an
_____
endotoxin
Mycobacterium (eg. M. tuberculosis) are unique in that they contain layers of _____. These bacteria cannot be gram stained, so an ____ stain is used.
mycolic acid; acid-fast
_____ are secreted by both gram positive and gram negative bacteria. These toxins are responsible for the symptoms and unique features of the illness which occur via the multitude of illnesses.
Exotoxins
Gram positive bacteria cell wall
2 layers-
● Inner cytoplasmic membrane
● Thick outer peptidoglycan layer
● Teichoic acid
Gram negative bacteria cell wall
3 layers
● Inner cytoplasmic membrane
● Periplasmic space
● Very thin middle peptidoglycan layer
● Outer membrane with LPS
● Contains no Teichoic acid
Bacteria have multiple _____ which help them colonize, spread, and/or evade the immune system
virulence factors
_____- loops of DNA which can replicate separately to the bacterial chromosome
Plasmids
____- short strands or filaments that act as adhesins, allowing them to adhere to certain tissue
Pili
______- gelatinous covering of the cell, allows resistance to phagocytosis. Responsible for the different serotypes within a bacteria
species. This is used for identification of the bacteria and as a target of vaccines. eg. Pneumonia vaccine (PCV), N. meningitidis vaccine
Capsules
_____- allows for bacteria to be motile, allowing movement towards a nutrient source
Flagella
_____- “glycocalyx” layer allows adherence to surfaces. eg. Skin, teeth (plaque), heart valves (endocarditis), prosthetic joints, catheters. P.
aeruginosa is a common problematic species in nosocomial infections. Difficult for antibiotics to penetrate.
Biofilms
_____- form in response to adverse conditions ie. reduced nutrients. A keratin like coating is formed which protects the DNA, and the cell from heat, dehydration and chemicals and antibiotics
Spores
______- Bacteria produce several types of enzymes that contribute to their pathogenicity. Including increased ability to invade tissues, form clots, deactivate IgA and IgG, and antibiotic resistance. eg. collagenase, hyaluronidase, coagulase, immunoglobulin protease
Enzymes secretion
______ - Function as part of the cell wall of gram negative bacteria. Genes lie in the bacterial chromosome itself and are less toxic than exotoxins, but can produce fever and hypotensive shock, leading to septic
shock. These toxins bind to receptor surfaces on macrophages
Endotoxins
Example categories of exotoxins
● Pyrogenic toxin- cytokine release leading to fever, rash, toxic shock syndrome eg. S. aureus, Strep pyogenes
● Enterotoxin- act on the GI tract leading to infectious diarrhea and/or food poisoning
● Neurotoxin- directed at nerves and their motor end plates leading to paralysis or in certain toxins, causes tetanus
_____ are secreted by both fram positive and negative bacteria. Genes can be found on plasmids or bacteriophages. Often have an A (toxicity) and B (binding site) fragments. Extremely toxic
Exotoxins
