EX 1 - Biology of Infectious Agents 2- Igboin Flashcards
Bacterioides
- Gram -ve rods
- Strict anaerobes but tolerate short exposure to O2
- Vertebrate intestinal flora (B. fragilis)
- metabolize complex carbs
How can bacteriodes tolerate short exposure to oxygen?
Secrete superoxide dismutase (SOD) and catalase (enzymes) that detoxify and breakdown reactive oxygen species (ROS)
Fluid filled space btw the organs contained in the abdomen. Susceptible to contamination more than any other place in body
Peritoneal Cavity
How can the peritoneal cavity become infected?
Spillage of intestinal material (ruptured bowel, appendix, abdominal surgery) into cavity can be catastrophic
- few mls of intestinal fluid: billions of bacterial cells, 100s of differentspecies
What are the characteristics of infections of peritoneal cavity?
- Results in bisphasic disease- acute inflammation leads to localized abscess
- Few species predominate in these abscesses, although 100s introduced into PC
Intra-abdominal infections typically result in ____ disease
bisphasic
What is the most common bacterial species isolated from abcesses?
B. fagilis
Why is B. fragilis the predominant species in intra-abdominal abscesses?
- Evades phagocytosis (caspule)
- Tolerates initail oxygenated environment (tolerant anaerobe)
- Thrives once environment becomes anaerobic
How are abscesses harmful to the host?
- Reservoir for bacteria to enter blood causing secondary infections (sepsis/septic shock)
- can extend to nearby sites and cause tissue necrosis
How can abscesses be diagnosed?
- CAT scan
- Culture abscess fluid drained under anaerobic conditions
How are abscesses treated?
- Combined surgical -medical therapy
- Drain abscesses, surgically repair, antibiotics
Severe systemic illness characterized by hemodynamic derangement and multiple organ malfunction, brough about by interaction of microbial products w/ host reticuloendothelial cells (macrophages)
Sepsis
What is it called when the circulatory system goes ape:
- high cardiac output
- low bp
- inadequate perfusion of organs (kidney, liver, gut)
Hemodynamic derangement- causes organ failure
___________ is the presence of bacteria in the blood, with or without the presence of blood
Bacteremia
T/F Sepsis does not = bacteremia
True
What microbial components trigger sepsis?
- LPS- gram -ve
- Peptidoglycan- gram +ve
What are the primary cytokine mediators of sepsis?
Proinflammatory cytokines
- IL-1
- TNF-a
- -released by macrophages
What are the effects of IL-1 and TNF-a on the vasuclature?
- Vasodilation- dec bp
- Vascular lekeage: edema
- Intravascular coagulation (blood clots): impedes blood flow, consumes clotting molecules, inc bleeding
- Inc expression of neutrophil adhesion molecules: degranulation in tissue (ROS + degradative enzymes) + tissue damage
What is the damage caused by sepsis?
- Hemodynamic derangement
- Multi-organ dysfunction syndrome (MODS)
- Shock phase
What is the treatment for sepsis?
- Ventilator (high O2)
- IV fluids ( inc bp volume/bp)
- Adrenergic drugs ( inc tissue perfusion)
- Antibiotics
Without ___ a patient will die from sepsis
antibiotics
- even w/ treatment sepsis at shock phase has > 50 % mortality
What are the general characteristics of Treponemes?
- Helical shape
- Corkscrew-like movement mediated by periplasmic flagella
T. pallidum causes _____
syphilis
What are the 2 modes of T.pallidum transmission?
- Sexual (mucous membranes- skin abrasions)
2. Transplacental
