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29 Cards in this Set

  • Front
  • Back
Infectious agents are all over. Why don't we get sick all the time?
(Hint... Rule #1)
1) The virulence depends on the host-microbe interplay.
2) Normal Flora competes with pathogens
3) The weak, immuno-comprimised are, to an extent, more susceptible
What are the four most common routes of infection?
1) Mucosal (Resp, GI, Genital, Ocular)
2) Skin (via abrasions)
3) Direct injection (Needles, vampires)
4) Endogenous (normal flora)
How do colonized, infectious agents, spread to distant sites though out the body?
(3 basic mechanisms)
1) Direct propogation
2) Blood/ lymph
3) Nervous Tissue
What are the two types of viruses that can spread though nervous tissue?
Herpes Simplex and Rabies
Both can lead to encephalitis
Infectious agents cause disease by a variety of mechanisms:
Name two
Release of exotoxins and tissue damaging substances (proteases)
Resisting phagocytosis
List three factors that contribute to the virulence (ability to cause disease) of the microbe.
1) Contagiousness
2) Evasion from immune system
3) Subversion of the immune system
What is the general pathology of chronic liver disease?
Immune response targets viral-infected cells.
It has been proven in animals that Neisseria Meningitis in the presence of CD__ in the meningeal tissue enables colonization.
What causes E. Coli O157:H7 to release its toxins?
Administration of antibiotics
What causes Corynebacterium Diptheriae to release it's toxin?
Low levels of iron
What causes Pseudomonas aeriginosa to release its toxin?
Interferon-gamma IFN-Υ
What bacteria would you suspect with a pt who cut their hand while cleaning an aquarium?
Aquatic bacteria such as Mycobacterium marinum
How does one become infected with anthrax?
Skin penetration of bacillus anthracis spores.
What type of bacteria would you suspect in a dog bite?
Francisella tularensis
What type of bacteria is commonly transmitted in a hut tub?
Pseudomonas Aerigonosa. The warm water opens the pores.
What organism would you suspect in the case of gastric or duodenal ulcers?
Helicobacter pylori
What bacteria can invade (translocate through an M cell), survive and grow in a phagocyte?
Superficial infections are caused by what type of bacteria? (aerobe, anaerobe, chemotroph, organotroph, thermophile?)
Aerobe or facultative aerobe.
Where, anatomically, are the main reserves for Staphylococcus aureus? (20-60%)
What else is prevelant there?
Anterior Nares
Staph epidermidis 90%
Propionobacterium acnes 80%
What organisms are found in the posterior nares?
Corynebacterium species
Streptococcus pneumoniae
haemophilus influenzae
moraxella catarrhalis (children)
How does normal flora protect you from pathogenic microorganisms?
5 methods
1) Occupy and displace pathogens from binding sites
2) Secrete mucins that prevent attachment
3) Secrete inhibitory metabolic products like fatty acids that lower the Eh (Activity of electrons) and pH
4) Compete with potetial pathogens for nutrients
5) Produce antibacterial substances: Bacteriocins, colicins.
What makes up the dental flora?
Anaerobic or facultative anaerobes such as:
Streptococcus mitis
S. Mutans
S. Sanguis
How does S. Mutans stick to the dental pellicle?
Converts sucrose to polysaccharides. Why sweets cause cavities?
What organism from the oral flora can lead to endocarditis?
Strepto. Sanguis
What two bacteria can survive in the stomach?
Myco Tuberculosis and Helicobacter pylori.
90% of intestinal flora fall into two phyla. What are they?
Bacterioidetes (Gram -) and Firmocutes (Gram +)

Bacteriodes (30% of fecal)
B. Fragilis and B. thetaiotaomicron

and Firmocutes (Gram +)
Peptostreptococci, enterococci, lactobacilli, Clostridia (C Perfingens)
What is bacterial translocation?
The passage of viable resident bacteria from the GI to normally sterile tissues such as the mesenteric lymph nodes and other internal organs.
What is bowel overgrowth syndrome?
Caused by reduced motility, immune suppression, proton pump inhibitors. Normal colonic bacteria move into small intestine and transform nutrients to toxic metabolites.
What are the symptoms of someone suffering from Bowel overgrowth syndrome?
Bloating cramping, nausea, steatorrhea
Bleeding (Vitamin K deficiency)
Malnutrition (Megaloblastic anemia B12 deficiency which leads to peripheral neuropathies)