Human Microbes Interaction Flashcards
(42 cards)
Colonization
-The PROCESS of growth of a microorganism after it has entered the host tissue
Host
-an organism that harbors a parasite
Parasite
-An organism that grows in or on a host AND causes damage (a negative outcome, some worse than others)
Infection
-the OUTCOME of growth of organisms in a host (not necessarily detrimental) colonization is the PROCESS, and Infection is the OUTCOME
Disease
-An injury or impaired function to the host
Pathogen
-A microbial parasite that causes disease
Obligate pathogen
-Always causes a disease and generally do not survive long outside the host
opportunistic pathogen
-Do not normally cause disease and do not cause disease in a host with normal resistance properties, but can in an impaired host
Pathogenicity
-The ability of an organism to cause disease (Some E. Coli strains never cause disease, some do)
Virulence
-The DEGREE of pathogenicity of an organism (Some E. Coli strains cause only mild disease, some cause life-threatening disease)
How is the normal human microflora beneficial?
-Competes with pathogens for space and nutrients (pathogen exclusion)
-produces products that inhibit pathogens (kills them)
-Synthesize vitamins for host
-Stimulate development of Immune system (germ free mice -> poorly developed immune systems)
What sites on the human body are colonized by normal microflora?
-Skin
-Oral Cavity
-Lower Respiratory Tract
-Urethra
What type of organisms are found on the skin?
-Gram + Cocci (staphylococcus) on skin, and Propionibacterium in follicles
-resistant to salts and oils
What type of organisms are found in the oral cavity?
-Gram positive cocci in mouth and throat
-Staph and Strep
-Streptococcus mutans (caries), anaerobes in gingival and plaque
What type of organisms are found in the lower respiratory tract?
-Bronchi and lungs are relatively sterile
What type of organisms are found in the urethra?
-Gram-facultative organisms such as E. Coli
-Upper urethra and bladder are relatively sterile.
-Vagina is staph and strep, except during fertile years, pH is lower and then lactobacilli predominate
What are some of the more important Genera of bacteria in the human gastrointestinal tract and why are they important?
-Helicobacter = ulcers
-Bacteroides = most abundant
-Escherichia = fecal contamination indicator
-Methanobrevibactor is rare archaea associated with humans
-clostridium difficile
What does C. difficile become a problem?
-Following antibiotics treatment that disrupts the normal flora and allows C. diff to become a predominant organism
-Some strains have a high antibiotic resistance and high levels of toxin production
Why do patients often get recurrences of C. difficile infections?
-Spores are resistant to antibiotics
-Spores are hard to remove from hospitals
-It takes time to regenerate flora that can exclude the C. diff from re-growing to dominant population.
Regions of the body in direct contact with exterior
-Nose
-mouth
-respiratory tract
-alimentary canal
-female genital tract
-urinary tract (male and female)
Where is normal flora found?
-almost all skin surfaces and mucus membrane surface are colonized by microflora
How many human and bacterial cells are in the body?
-Approximately 10^13 human cells in your body
-Approximately 10^14 bacteria cells in/on your body
-human: bacteria = 1:100
Microflora of the skin
-The first line of defense: dry, acidic, and salty
-Flors is dependent upon weather, age and, hygiene
-Anaerobes (Propionibacterium acnes) grow in hair follicles and sebaceous fluids
-Skin flora is dominated by gram-positive cocci
Layers of the skin with a hair follicle
-dead layer or epidermis = dead and sloughs off
-dermis with duct and sebaceous gland (makes oil)
-Subcutaneous = has apocrine sweat gland, live cell, if get here it will cause infection
