Lecture 1 Flashcards
What are some examples of selective environments in the body where growth of some organisms is favored over others?
Examples of selective environments in the body where growth of some organisms is favored over others are skin, lungs, and intestine. Organisms resistant to dehydration, like S. aureus, are favored in skin environments. In lungs, highly oxygenated, obligately aerobic organisms, such as Mycobacterium tuberculosis, are favored. In the intestine, organisms that require an anaerobic environment, like the Clostridium genus, are favored.
How can antibiotics affect the microbiome?
Antibiotics can deplete the microbiome and cause an overgrowth of bacteria.
What are the major bacteria found in the stomach, small intestine, and large intestine?
The major bacteria found in the stomach are lactobacilli. The major bacteria found in the small intestine are enterococci and lactobacilli. The major bacteria found in the large intestine are many, including enterobacteria, clostridia, Enterococcus faecalis, and lactobacilli.
Pathogens
Pathogens are agents that cause disease.
Virulence
Virulence refers to the degree of potency of a pathogen.
LD50
LD50 is the dose of an agent that kills 50% of a test population
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What are the five important features of diagnosis?
The five important features of diagnosis are treatment, prevention of infection, control measures, epidemiology and spread of infection, and sources of infection.
What are the types of specimens used in bacterial diagnosis?
The types of specimens used in bacterial diagnosis are direct specimens collected from normally sterile tissue or fluid, indirect samples that are samples of inflammatory exudates that have passed through sites of infection, and samples from normal flora sites. These bacteria can have issues with bacterial diagnosis as they dominate the makeup of the flora at the site. These bacteria require selective media.
What are some factors that influence bacterial growth?
Some factors that influence bacterial growth are temperature, pH, carbon, oxygen, and nitrogen.
What type of temperature do human pathogens like?
Mesophiles
Facultative aerobe
Facultative aerobes can grow in either condition but prefer aerobic conditions.
Microaerophilic bacteria
Microaerophilic bacteria need oxygen but at lower concentrations
Aerotolerant anaerobes
Aerotolerant anaerobes do not need oxygen to grow but can tolerate its presence.
What is agar and how is it used in bacterial culture?
Agar is a sulfated polymer extracted from red algae. Liquid media can solidify with the addition of 1-2%. A culture medium is a solid or liquid preparation used to grow, transport, and store microorganisms.
What are the different types of media used for bacterial culture?
The different types of media used for bacterial culture are synthetic/defined, complex, selective, differential, and enriched media.
