Flashcards in Infectious Agents Biology Deck (46):
60-80% of microbial infections are caused by _____
Oral biofilm bacteria are not randomly distributed, rather they ______ into clumps
Formation of Biofilms (steps):
1. Reversible adsorption of bacteria
2. Irreversible attachment "Sessile"
3. Multiply, microcolonies
4. Exopolymer production -> biofilm established
5. Incorporation of other bacteria/materials into biofilm
Bacteria attach to ______, NOT directly to surfaces
Irreversible adsorption is caused by _____
Bacterial needs that drive cooperative consortia formation:
Physical- bind to other species on surface
Nutritional- by products of metabolism, enzymes, proteins
Respiratory- anaerobes co-aggregate with facultative anaerobes
Mature biofilm is made up of:
75-95% extra cellular polymer (web)
Release of bacteria from mature biofilm
Advantages (to microbes) of biofilm:
2. Rapid acquisition
3. Nutritional (pool resources)
Advantages (to host) of biofilm:
1. Prevent colonization of harmful organisms (competition)
Process of cell-cell communication by which bacteria monitor the density of members of their species, and other species, in an environment to synchronize behaviors
Gram negative QS general mechanism components:
1. Signal molecule: autoinducer (AHL) made by LuxI
2. Receptor/Response regulator: LuxR
Gram+ general mechanism components:
1. Signal molecule: Oligopeptide
3. Response regulator
3rd general mechanism of QS components:
1. Signaling molecule: AI-2
2. Made by G positive and negative species
3. Interspecies communication
Quorum Sensing can trigger:
2. Expression of virulence gens
3. Biofilm formation
You can either target the _____ or the _____ in QS to inhibit biofilm formation
Gram- rods, strict anaerobes, normal residents of vertebrate intestinal and oral microbiomes, dominant genera, metabolize complex carbs
Bacteriodes have these two enzymes to detoxify and breakdown ROS
1. Superoxide Dismutase
Why is B. Fragilis the predominant species in the intra-abdominal abscesses if it is not the most common Bacteriodes in the intestine normally?
1. It evades phagocytosis (anti-phagocytic capsule)
2. It tolerates the initial oxygenated environment of the peritoneal cavity
3. Thrives once the environment becomes anaerobic
How can abscesses harm the host?
1. Extends by tissue necrosis to nearby sites
2. Serve as reservoirs for bacteria to enter blood
How are abscesses diagnosed?
1. CAT scan
2. Culture abscess fluid (ID species)
How are abscesses treated?
Combined surgical/pharmacological approach
Characteristics of peritoneal cavity infections:
Biphasic (acute inflammation -> localized abscesses), few species predominate in abscesses
How can the peritoneal cavity become infected?
Spillage of intestinal material into cavity
Severe systemic illness characterized by hemodynamic derangement and multiple organ malfunction, brought about by interaction of microbial components with host macrophages. Begins with bacteremia (bacteria in blood).
High cardiac output yet low bp and inadequate perfusion of organs
In Sepsis, the host's own molecules cause the damage when ____ are recognized by ____.
PAMPs (Pathogen associated molecular patterns)
PRRs (Pattern recognition receptors)
Primary cytokine mediators of Sepsis?
Effect of IL-1 and TNF-alpha on blood vessels:
1. Vasodilation: lowers bp
2. Vascular leakage: edema, lowers bp
3. Intravascular coagulation
4. Increased expression of neutrophil adhesion molecules: degranulation, tissue damage
Treatment for Sepsis:
2. IV fluids
General characteristics of _____: Helical shape, corkscrew-like movement, periplasmic flagella.
Modes of T. pallidum transmission:
When T. Pallidum infects, it first enters ____ tissues for ______ replication. It is then carried through ____ channels to systemic circulation.
In primary syphilis, WBCs battle replicating spirochete and inoculation site, forming a lesion or a _____. This lesion increases risk of HIV infection.
In secondary syphilis, bacteria replicate in _____. The body develops rashes on one or more places, even on ____. Because there are many variable symptoms during this stage, it is known as the _____. When symptoms resolve but bacterium persist, this is known as ____.
Lymph nodes, liver, joints, muscles, skin, mucous membranes
Palms and soles
____ syphilis is caused by the host's response to T. Pallidum antigens. Leads to the destruction of host tissues.
Tertiary syphilis lesions that destroy soft tissue, bone, organs.
Tertiary syphilis -> neurosyphilis -> staggering (i.e. ___), dementia, and loss of motor function (i.e. ____)
How is syphilis diagnosed?
Detecting of antibodies (treponeme)
How is syphillis treated?
Possible reason for treatment failure?
Inability of penicillin to penetrate CNS
What causes Lyme disease?
B. Burgdorferi (Borrelia Burgdorferi)
What triggers the normally dormant B. Burgdorferi?
When tick feeds on mammalian blood-> injected into mammal from tick salivary glands
B. Burgodorferi spread within is human is facilitated by it's ability to bind human _____.
Stages of Lyme disease:
1. Localized skin infection- forms a lesion known as _____.
2. Disseminated infection- damage mediated by host's response to antigens, involves _____
3. Symptoms include:
1. Erythema migrants
2. IL-1 and TNF-alpha
3. Arthritis, Lyme Encephalopathy (memory, Sleep, speech affected), Acrodermatitis Chronica Atrophicans (atrophy of skin)
Lyme Disease is diagnosed by:
Detecting antibodies (ELISAs, Western blots)