Infectious Agents (Igboin) Flashcards
What is a biofilm?
Multicellular community of bacteria on a surface, encased in exopolymer
Does bacteria attach directly to a surface?
No. Attach to conditioning layer (salivary proteins, fibrin, etc.)
What causes the initial irreversible absorption of bacteria unto biofilms?
Adhesions
How do other molecules build on to the primary colonizers?
Co-aggregation: adhesion molecule and receptor
What are the three basic needs of a biofilm?
- Physical: adherence
- Nutritional
- Respiratory: anaerobes and facultative anaerobes
What is the difference between reversible and irreversible binding in biofilms?
Irreversible: adhesins and receptors
Reversible: smaller forces
What makes up the majority of a biofilm?
Spider web of extracellular polymers (75-95%)
What shape do the micro colonies make?
Mushroom
What are the two methods of releasing bacteria from the biofilm?
Active: enzyme
Passive: fluid flow and collision
What are the advantages for a microbe of living in a biofilm?
- Protection
- Rapid genetic sharing
- Lots of nutrients
What is quorum sensing? What is its purpose?
Cell-cell communication in bacteria where they monitor each other’s density
Purpose: synchronize behaviors such as biofilm formation
What is the difference between gram-and gram+ quorum sensing?
Gram-: 2 main components (autoinducer LuxI, receptor LuxR)
Gram+: 3 main components (oligopeptide, receptor, response regulator)
T/F: In quorum sensing, a higher cell population density will upregulate transcription.
TRUE
What is special about LuxS/AI-2 quorum sensing?
Proposed interspecies communication
What are the three classes of signaling molecules?
- AHL
- Oligopeptides
- AI-2
How can you block biofilm formation?
Block quorum sensing
What are some characteristics of bacteroides?
- Gram -
- Strict anaerobes
- Complex carbs
How do bacteroides withstand short exposure to O2?
Superoxide dismutase and catalase
What typically results from a intra-abdominal infection?
Biphasic diseases
B. Fragilis
Why is B. Frag the most predominant bacteria in PC abscesses?
- Phagocyte resistant
2. Oxygen tolerant
T/F: Abdominal abscesses allow for bacteria to enter the blood causing possible sepsis/shock.
TRUE
How are abscesses diagnosed?
CAT scan and cultures
How are abscesses treated?
Surgery and antibiotics
What is sepsis?
Systemic illness with multiple organ malfunction and hemodynamic derangement
How is sepsis treated?
- High O2
- IV fluids
- vasopressors
- Antibiotics
How is syphilis diagnosed?
Detect antibodies against the bacterium
How do you treat syphilis?
Penicillin
What are some general characteristics of treponemes?
- Helical shape
- Corkscrew movement
- Periplasmic flagella
Describe primary syphilis?
Syphilitic chancre formed and will heal spontaneously
What is part of secondary syphilis?
Patient develops rash due to systemic spread of bacteria
Can result in latent syphilis
What is associated with tertiary syphilis?
Development of lesions attacking various tissues in the body
GUMMAS
What causes lyme disease?
B. Burgdorferi
How does B. Burgdorferi (lyme disease) enter the human?
Via the salivary glands of deer tick
How does b. Burgdorferi spread?
Human plasmin
What are the three stages of lyme disease?
- Localized skin infection
- Disseminated infection in CNS (IL-1 and TNFalpha)
- Months to years later: arthritis
How is lyme disease detected and treated?
Detected: antibodies
Treatment: NO penicillin, doxycycline or amoxicillin
