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27 Cards in this Set

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endogenous infection
from normal body flora
exogenous infection
from an externally acquired virulent organism
Name some factors that influence bacterial colonization of certain body sites.
1. Space
2. Nutrients, substrate, moisture
3. Intrinsic clearing mechanisms
4. Anatomic separation from environment
Name bacteria common in skin flora.
Coagulase negative Staphylococcus
Staphylococcus aureus
Propionobacterium acnes
_____ play a role in nosocomial infections.
Hands
30% of people are chronic carriers of S. aureus. Where is the bacteria anatomically located?
nose and skin
True or false.
The mouth supports the growth of >300 species of bacteria.
True.

The mouth is enriched by ingested food, salivary and mucus secretions.
Name bacteria that are normal flora in the mouth and pharynx.
alpha hemolytic Streptococci (includes S. viridans)
Neisseria spp.

And in Derek's case: Group A Strep
______ and _______ normally assure a microbe-free environment in the lower respiratory tract.
Mucociliary clearing mechanisms
and
Alveolar macrophages
_____________ leads to loss of respiratory clearing mechanism and bacterial colonization that require PMN defenses with purulent sputum.
Respiratory viral infection
Due to high acid content there is a (High/Low) bacterial count in the stomach.
LOW

*Counts will transiently rise slightly shortly after eating.
**High counts seen in pathology.
Why are there low bacterial counts in the small intestine?
Small intestine has efficient motility to move things through quickly providing a cleansing effect.
*Disease may slow motility and lead to chronic diarrhea.
Why are there high counts of bacteria in the colon?
Slow motility leads to high bacterial counts. (10^12/gm of feces!)
True or false.

E. coli (aerobes) outnumber Bacteroides (anaerobes) 1000 to 1 in the colon.
False.

Bacteroides (anaerobes) outnumber E. coli (aerobes) 1000 to 1.
Name other bacteria that colonize the intestine.
Clostridia, Lactobacilli, anaerobic streptococcus, Enterococcus faecalis
Why does S. aureus make boils on the skin?
S. aureus is coagulase + so will decrease blood supply to the infected area (coagulase clots blood).
*This means that antibiotics are ineffective and the boil must be surgically drained.
S. viridans can be found as normal flora of the mouth. This organism can be released in to the blood stream during dental work and may cause _______.
Endocarditis

*especially in patients with damaged heart valves
When you see an abscess you should think ________.
(specific group of bacteria)
ANAEROBES = ABSCESS
Fecal contamination of the abdominal cavity by facultative aerobes will also allow the growth of strict anaerobes which leads to abscess formation. Why is this?
Facultative aerobes will reduce the oxygen levels (change the redox potential) to allow anaerobes to grow.
In vaginal flora, glycogen serves as a substrate for acid tolerant bacteria during reproductive years. Name some common vaginal flora.
Lactobacillus
Candida
(Also anaerobic Strep, diphtheroids, clostridia)
True or false.

The acid tolerant vaginal flora during reproductive years has an inhibitory effect on coliforms from the rectum and reduces the potential for UTI.
True.

UTI and bladder colonization are common during post-menopausal years.
Name the sterile body sites.
Blood
CSF
Joint fluid
Pleural fluid
Peritoneal fluid
Pelvic (Extra-vaginal) fluid
How does normal body flora influence pathogens?
Normal body flora utilizes space and nutrients of the body and also produces antibacterial catabolites.
What are some other ways normal flora may benefit the host?
Production of vitamins
Improved intestinal absorption
May lead to protective immunization against pathogens that have cross-reactive antigens
May be important in development of intestinal lymphatic system and local antibody formation
What criteria should you use to determine if a culture is normal flora or pathogen?
1. Consider if normal flora usually occurs in that body fluid.
2. Consider the pathogenic potential of the organism cultured. (Does it cause the symptoms that are present?)
How can normally "non-virulent" flora become pathogenic?
If normal flora have unchecked growth (such as in antibiotic therapy) or if host defenses are reduced.
Name some situtations where pathogenic flora may occur in certain individuals.
Hospital (MRSA)
Crowded military populations (N. meningitidis)
Gall bladder stones (S. typhi)
Cancer, leukemia, or lymphoma (Pseudomonas)
diabetics, burn patients (gram neg. bacilli)
AIDS patients (Herpes viruses, P. carinii)