Infectious disease Flashcards
Define: Normal Flora
Organisms that live symbiotically on or within humans but rarely cause disease
Example of normal flora on skin
staphylococci, steptococci
Example of normal flora in the oropharynx
streptococci, neisseria
Example of normal flora in the large intestine
E. Coli, Enteroccoci, Candida
Obligate pathogen
Causes disease in normal healthy humans
Opportunistic pathogen
Causes disease in compromised humans
Nosocomial Flora
Acquired from a health care setting
The establishment of infectious disease (stages)
- encounter
- entry
- multiplication and spread
- host tissue injury
Outcome(s) of infection
- Resolution (eradification )
- Chronic infection (HIV)
- Latent infection (herpes zoster)
- Death
Modes of transmission
- Contact
- Vehicle Transmission
- Vector Transmission
Modes of contact transmission
Direct: handshakes
Indirect: drinking classes, tooth brushes
Modes of Vehicle transmission
Airborne
Waterborne
Foodborne
Modes of vector transmission
- Mechanical- on insect bodies
2. Biological- Lice, mosquitoes, ticks
Cause of aspiration pneumonia
Inhaled infiltrate from the oropharynx that is colonized with upper airway flora
-Bacteria
Cause of aspiration pneumonitis
- chemical pneumonia
- Acidity of gastric contents results in chemical burns to the tracheobronchial tree, followed by an inflammatory response fueled by the release of cytokines
How does HIV affect the cellular component of the acquired immune system?
HIV produces a cellular immune deficiency characterized by the depletion of Helper T cells (CD4). The loss of CD4 results in the development of opportunistic infections and neoplastic processes.
CD4 counts less than what level is diagnostic of AIDS?
200
Tests used to diagnose HIV
Western blot, PCR HIV RNA and p24 antigen tests
How does HIV gain entry into Th Cells?
HIV gains access to mucosal surfaces by binding first to tissue macrophages
-Macrophages interact with CD4 T cells and CD4 cells become activated and infected.
