Lecture 12: Normal Microbiota and the Host Flashcards
Normal Microbiota _____ colonize the host
permanently
Transient microbiota may present in host for
days, weeks, or months
The relationship between nomral microbiota and the host
symbiosis
An association of two or more different species of organisms
symbiosis
Physical contact between dissimilar organisms
Symbiont
What is commensalism
An association between two organisms in which one benefits and the other is unaffected
What is mutualism
both organisms benefit
What is parasitism
One organism benefits at the expense of the other
Microbial antagonism is a ____ between microbes
competition
Normal microbiota protect the host by:
- Occupying niches that pathogens might occupy
- Producing acids
- Producing bacteriocins
What is a Microbiome
- All the genes of the host and the microbiota
Superorganisms
- Emerge when the gene-encoded metabolic processes of the host become integrated with those of the microbe
- a blend of host and microbial traits where host and microbial cells cometabolize various substrates, resulting in unique products
Germfree animals can be used
- can be used to study effects of microbes on animal health by
- comparing gerfree animals to normal animals
- introducing a single microbe to the germfree animal and observing effects
- Can be coupled with genomic studies for maximum benefits
What are Germfree animals produced
- Cesarean section, raised in sterility
What is the Human Microbiome Project
- Attempt to define ‘normal’ populations of microbes in and on human beings
as of 2012 the human microbiome project had genome reference collection for ___ microorganisms (out of an anticipated 900) obtained
178
What are the reasons to study Normal Human Microbiota
- 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 in stimulating immune responses
Bifidobacteria is found in
- breast fed babies
What is Protrophic
- can synthesize all amino acids and growth factors from simple carbohydrates
Normal microbiota protect the host by
- competing with pathogens or altering the environment
- occupying niches that pathogens might occupy
- Producing acids
- Producing bacteriocins
Probiotics
- Live microbes applied to or ingested into the body, intended to exert a beneficial effect
Members of normal microbiota that produce disease under certain circumstances
Opportunistic pathogens
Debiliated host with lowered resistance to infection
Compromised host
Normal Microbiota of the skin
- Mechanically strong barrier
- Inhospitable environment
- slightly acidic pH
- high concentration of NaCl
- many areas low in moisture
- Inhibitory substances (e.g., lysozyme)
- mostly Gram-positive, salt tolerant bacteria
- Staphylococci (ex. S. epidermis)
- Micrococci (ex. M. luteus)
- Diphtheroids
- Aerobes on surface
- Corynebacterium xerosis
- Anaerobes in hair follicles
- Propionibacterium acnes
- Aerobes on surface
- a few gram-negative organisms (ex. Acinetobacter)
- grow on oils
- yeast
- ex. Malassezia furfur
- yeast
Anaerobes in hair follicles
Propionibacterium acnes
is the bacteria on the skin gram positive or gram negative
mostly gram positive with a few gram-negative organisms (ex. Acinetobacter)
Acne Vulgaris
- Caused in part by activities of Propionibacterium acnes
- Sebum
- fluid secreted by oil glands
- accumulates, providing hospitable environment for P. acnes
- Comedo
- plug of sebum and keratin in duct of oil gland
- results from inflammatory response to sebum accumulation
Normal Microbiota of the eye
- From birth throughout a human life, small numbers of bacterial commensals are found on the conjunctiva of the eye
- The predominant bacterium is Staphylococcus epidermis
Normal microbiota of the external ear
similar to skin flora as well as fungi
Normal Microbiota are responsible for dental caries examples:
- S. mutans
- Lactobacillus
Normal Microbiota of the Mouth
- Contains organisms that survive mechanical removal by adhering to gums and teeth
- Contribute to formation of dental plaque, dental caries, gingivitis, and periodontal disease
- Within hours of birth, the oral cavity is colonized by microorganisms from the surrounding environment
- Oral bacteria are responsible for dental caries (ex. S. mutans and Lactobacillus)
- Suppress pathogens by competitive inhibition in upper respiratory system
What two bacteria are found inside the nostrils
- Staphylococcus aureus
- S. epidermis
The Pharynx and trachea contina Gram____ bacteria:
- gram positive bacteria
- Staphylococci (ex. S. epidermis)
- Micrococci (ex. M. luteus)
- Diphtheroids
- Streptococci (both alpha and beta-hemolytic
Nasopharynx may contian low numbers of potentially pathogenic microbes such as
- Streptococcus pneumoniae
- Neisseria meningitidis
- haemophilus influenza
- Mycoplasmas
Does the lower respiratory tract have a normal microbiota
- No
- Microbes moved by:
- Continuous stream of mucous generated by ciliated epithelial cells
- cilliary escalator
- Phagocytic action of alveolar macrophages
- lysozyme in mucus
- Continuous stream of mucous generated by ciliated epithelial cells
Most microbes of the stomach are
- killed by acidic conditions
- some survive if pass through stomach very quickly
- Some can survive if ingested in food particles
Which part of the small intestine has the most microbes
- The ileum
- flora present becoming similar to that in colon
- pH becomes more alkaline
What has the largest microbial population in the body
The large intestine (colon)
The microbial population of the large intestine (Colon) is eliminated from body by _____ but replaced rapidly by
- peristalsis, desquamation, and movement of mucus
- High reproductive rate
most of the microbes in the large intestine (colon) are
anaerobes
Microbes in the large intestine (colon)
- E.coli
- Bacteroides
- Fusobacterium
- Lactobacillus
- Enterococcus
- Bifidobacterium
- Enterobacter
- Citrobacter
- Proteus
- Klebsiella
- Candida (fungus)
What parts of the genitourinary tract is normally free of microbes
Kidneys, ureter, and bladder
Why is the female genital tract’s microbiota in a complex state of flux due to ______ with ______ predominating
- menstrual cycle
- Acid-tolerant lactobacilli
_______ microbiota are predominant in the vagina
- Lactobacilli
- produce H2O2
- Grow on glycogen secretions
Urinary infection is indicated by
- > 10,000 bacteria/mL
- 100 coliforms/mL
- Positive urine leukocyte esterase (LE) test
The “extinction” of H. pylori is linked to several immune and metabolic disorders such as
Asthma, allergies, celiac disease, even acid reflux disease
