Normal and Transient Flora;Normal and Transient Flora;Host/Parasite RelationshipsHost/Parasite Relationships

Microbial EcologyMicrobial Ecology

The study of microorganisms and their environment.

www-esd.lbl.gov

SymbiosisSymbiosis

“living together”Describes the interactions that occur

between two dissimilar organisms (usually 2 different species) that live together or are in close association with one another.

Symbionts the organisms that live together in such a

relationship.

NeutralismNeutralism

Symbiotic relationship in which neither symbiont is affected by the relationship.

Both species are unaffected.

CommensalismCommensalism

Symbiotic relationship in which one symbiont benefits and the other species is not affected (neither harmed nor helped).

Ex. Propionibacterium many species in this genera live on the skin and are thought to

neither hurt nor help humans.

Host An organism that harbors another organism.

MutualismMutualism Symbiotic relationship

that is beneficial to both symbionts.

Ex. Termites and protozoa

Ex. Lichens

Ex. Some species of our microflora (i.e. Escherichia coli.)

Termite

Lichen. botit.botany.wisc.edu

E. coli. www3.niaid.nih.gov

Parasitism Parasitism

Symbiotic relationship in which one symbiont is benefited and the other is harmed.

Ex. Sheep liver fluke

Ex. Opportunistic pathogens of our normal flora.

Sheep Liver Fluke. locksparkfarm.wordpress.com

Synergistic Relationship Synergistic Relationship When two (or more)

microorganisms “team up” to cause a disease that neither could cause by itself.

Called synergistic infections.

Ex. Acute necrotizing ulcerative gingivitis (i.e. “Trench Mouth).

Acute necrotizing ulcerative gingivitis.

www.ohiohealth.com

Normal Flora of HumansNormal Flora of Humans All microbes that reside on and

within a person.

Most commonly inhabited parts of the body.

Eyes Skin Mouth Ears Upper respiratory tract Gastrointestinal tract Genitourinary tract

www.scq.ubc.ca

When do microorganisms take up When do microorganisms take up residence in humans?residence in humans?

Establishing Normal Flora Establishing Normal Flora

www.ehponline.org www.solarnavigator.ne

Transient FloraTransient Flora

Live temporarily on the body.

Often “picked up” from our daily routines.

Why are they temporary?

Importance of Normal FloraImportance of Normal Flora

Often helps prevent infection.

Prolonged use of antibiotics can cause an imbalance.

Ex. Candida albicans

Candida albicans. www.humanillnesses.com

Candida albicans infection. www.lib.uiowa.edu

Microflora of the SkinMicroflora of the SkinConsists of mostly bacteria and fungi.

Most are anaerobes, although some are aerobic.

Anaerobes live in the: deeper layers of the skin hair follicles sweat and sebaceous glands

health.howstuffworks.com

Microflora of the SkinMicroflora of the Skin

The number and variety of microorganisms depends on the:

Amount of moisture present pH Temperature Salinity Presence of chemical wastes such as urea and fatty

acids Presence of other microbes (which may produce

toxic substances)

Groups of Normal Skin FloraGroups of Normal Skin Flora

1. Diphtheroids (Coryneforms) Gram-positive, non-spore forming

rods. Ex. Propionibacterium acnes.

2. Staphylococcus spp. Gram-positive cocci usually arranged

in clusters. Helps maintain normal flora balance.

3. Yeasts – Candida spp. Single-celled fungi. Ex. Causes tinea versicolor.

Propionibacterium acnes. bacteriality.com

Tinea versicolor. georgiahealthinfo.gov

Microflora of the Eyes and EarsMicroflora of the Eyes and Ears Ears

Middle ear and inner ear sterile.

Outer ear and auditory canal contain same types of microorganisms as are found on the skin.

Eyes Does contain some

microorganisms. Tears, mucus, and sebum

that are produced in and around the eye greatly reduce many microorganisms.

www.bluedothealth.com

www.infovisual.info

Respiratory TractRespiratory Tract

Upper Respiratory Tract Nasal passages Throat (pharynx)

Lower Respiratory Tract Larynx (voice box) Trachea Bronchi Bronchioles Lungs www.uic.edu

Microflora of the Respiratory TractMicroflora of the Respiratory Tract

Upper Respiratory Tract Nasal Passages and Throat

– Have many species of microorganisms.– Provide moist, warm environment.– Many are harmless.– Some are opportunistic pathogens.– Some people are carriers of virulent pathogens.

Lower Respiratory Tract Usually microbe free.

Microflora of the Upper Respiratory TractMicroflora of the Upper Respiratory Tract Staphylococcus spp.

Gram-positive cocci in clusters. Often includes S. aureus.

Corynebacterium spp. Gram-positive rods; nonmotile; nonspore-forming. Nonpathogenic species. Collectively called diphtheroids.

Moraxella spp. Gram-negative diplococci. Resemble Neisseria species.

S. aureus

Corynebacterium spp.

Moraxella spp.

Microflora of the Upper Respiratory Microflora of the Upper Respiratory Tract cont.Tract cont.

Haemophilus spp. Small, gram-negative rods. Often includes H. influenzae.

Bacteroides spp. Small, gram-negative rods. Strict anaerobes.

Streptococcus spp. Gram-positive streptococci in chains. Often includes S. pneumoniae.

H. influenzae

Bacteroides fragilis

Streptococcus spp.

Microflora of the Oral CavityMicroflora of the Oral Cavity Provides great shelter and nutrients

for many species of microbes. Flourish in gum margins, crevices

between teeth, and deep fold of the tonsils.

Bacteria feed on food particles and dead epithelial cells.

Poor hygiene can lead to periodontal diseases.

Most common microbes are species of alpha-hemolytic streptococci.

anatomy.med.umich.edu

Gastrointestinal TractGastrointestinal Tract

Digestion of food, absorption of nutrients, and elimination of undigested material.

Includes: Oral cavity and throat (already

discussed) Esophagus Stomach Small intestines Large intestines Anus

www.giconsults.com

Microflora of the Gastrointestinal TractMicroflora of the Gastrointestinal Tract Stomach

Acidic environment prevents much growth. Exception – Helicobacter pylori – found in some people causes ulcers.

Small Intestine Upper part of small intestine (duodenum) – little growth due to bile. Lower portion of small intestine (jejunum and ileum) – more

microbial growth present. Large intestine (colon)

Contains the largest number and variety of microbes. 500-600 species. Anaerobic environment. Contains obligate anaerobes, aerotolerants, and facultatives. Many are opportunistic pathogens if enter other areas of the body.

Genitourinary TractGenitourinary TractUrinary Tract

Kidneys Ureters Urinary bladder Urethra

Male and Female Reproductive Systems

www.pvurology.org

Microflora of the Genitourinary TractMicroflora of the Genitourinary Tract Healthy kidneys, ureters, and urinary bladder are

sterile. Urethra harbors many microbes (i.e. yeasts, bacteria, and

viruses). Usually don’t invade bladder due to acidic nature of urine. UTI (urinary tract infections) occur when microbes travel up

the urethra and multiply.

Male and female reproductive systems are sterile with the exception of the vagina.

Type of growth depends on stage of sexual development. pH of vagina changes throughout sexual development

providing different environments for different organisms.

The EndThe End