12- Normal Microbiota And The Host Flashcards
Transient microbiota?
Microbiota that may be present for days, weeks, or months
Symbiosis?
- the relationship between normal microbiota and the host
- an association of two or more different species of organisms
Commensalism?
When one organism benefits and the other is unaffected
Mutualism?
When both organisms benefit
Parasitism?
When one organism benefits at the expense of the other
Microbial antagonism?
Competition between microbes
How do normal microbiota protect the host?
- occupying niches that pathogens might occupy
- producing acids
- producing bacterocins
Probiotics?
Live microbes applied to or ingested into the body, intended to exert a beneficial effect
Normal microbiota?
Microbiota that permanently colonize the host
What are opportunistic pathogens?
Members of normal microbiota that produce disease under certain circumstances
What is a compromised host?
A debilitated host with lowered resistance to infection
These oral bacteria are responsible for dental caries?
- S. mutans and Lactobacillus
What is the goal of the Human Microbiome project?
To attempt to define ‘normal’ populations of microbes in and on human beings
Name some reasons it would be beneficial to study normal microbiota (3).
- to gain insight into possible infections resulting from injury
- to understand causes and consequences of overgrowth of microbes normally absent from a body site
- to increase awareness of role played by indigenous microbe(s) in stimulating immune response
Sebum?
Fluid secreted by oil glands
Comedo?
- plug of sebum and keratin in duct of oil gland
- results from inflammatory response to sebum accumulation
Acne vulgaris is caused in part by the activity of what bacteria?
Propionibacterium acnes
These gram-positive, salt-tolerant bacteria are part of the normal microbiota of the skin?
- staphylococci (S. epidermis)
- Micrococci (M. luteus)
- Diptheroids – aerobes on surface (Corynebacterium xeroxis)– anaerobes in hair follicles (Propionibacterium acnes)
These are predominant bacteria found just inside the nostrils?
Staphylococcus aureus and S. epidermis
These gram-positive bacteria are found in the pharynx and trachea?
- Staphylococci (S. Epidermis)
- Micro cocci (M. luteus)
- Diptheroids
- Streptococci (both alpha- and beta-hemolytic)
These potentially pathogenic microbes may be present in the pharynx?
- streptococcus pneumoniae
- Neisseria meningitidis
- Haemophilus influenzae
- mycoplasmas
Why is there normal microbiota in the lower respiratory tract?
Microbes are moved by:
- continuous stream of mucous generated by ciliated epithelial cells (ciliary escalator)
- phagocytic activation of alveolar macrophages
- lysozyme in mucus
Are there many or few microbes present in the stomach?
Few. Most microbes are killed by acidic conditions
- some survive if they pass through the stomach very quickly
- some can survive if ingested in food particles
Where is the largest microbial population of the body found?
In the large intestine (Colon)
List some characteristics regarding the microbiota of the large intestine (Colon).
Largest microbial population now the body
- microbes are eliminated from the body by peristalsis, desquamation, and movement of mucus
- microbes are replaced rapidly because of their high reproductive rate
- most of the microbes present are anaerobes
List some of the normal microbiota found in the large intestine (colon).
- E. Coli
- Bacteroides
- Fusobacterium
- Lactobacillus
- Enterococcus
- Bifidobacterium
- Enterobacter
- Citrobacter
- Proteus
- Klebsiella
- Candida (fungus)
These bacteria are predominant in the vagina?
Lactobacilli
These areas of the genitourinary tract are normally free of microbes?
- Kidneys
- Ureters
- Bladder
You may find a few microbes normal present in this area of the genitourinary tract?
The distal portions of the urethra
The ______ the urethra, the more likely to develop infections?
Shorter
