Microbiology Exam 3

Benefits of Microflora #1

Normal flora outcompetes pathogenic bacteria Utilizes available real-estate Utilizes available nutrients Often secrete antimicrobials that kill competitors S epidermidis (good) vs. S pyogenes (bad) Commensal

Normal Microbiota of the Gastrointestinal Tract

Normal human intestine has 1011-1013 bacteria per gram of feces Populated by anaerobes and facultative anaerobes (1000 to 1 ratio) Strict anaerobic or facultative anaerobes 5-10% of caloric uptake is due to absorbing microbial fermentation byproducts Microbes are usually not found attached to the intestinal surface (exception: some pathogens) -Barrier of mucus Most microorganisms found in the lumen Most are in the center of that tube (lumen) Over 2 pounds of your weight are the microbiota in your gut

Opportunistic pathogens

Normal microbiota that cause disease under certain circumstances Conditions that provide opportunities for pathogens: -Introduction of normal microbiota into unusual site in body -Immune suppression -Changes in the normal microbiota Not in places are supposed too, changes in normal microbiota (antibiotics), etc

Basophils

innate immune cell (0.5-1% of leukocytes) Associated with allergic reactions Release histamine and heparin Mast cells similar to basophils but reside in tissue Rarest of leukocytes Dilate blood vessels and make them leaky (more fluid movement and more fluid leaving)

lymphatic system

vessels that collect lymph and return it to the blood

Hematopoiesis

(one stem cell thats the precursor for red bloods cells, platelets, and white blood cells)

2nd line of defense in the immune system

(true innate immune system) this is what you are born with and works as soon as your born (cellular defenses and interferons, complement, inflammation and fever) phagocytosis, complement, interferons, inflammation, fever

Which of the following body compartments is NOT sterile in healthy individuals? A) Oropharynx B) Heart C) Kidneys D) Blood E) Cerebrospinal fluid

A Others would indicate serious infection

Wounds

Access to deeper tissues allows skin microbiota to become opportunistic Trauma to any tissue of the body -Cuts, scrapes, surgery, burns, bites, etc. Allow microbes to infect the deeper tissues of the body -In most cases, other body defenses eliminate infection -Can result in severe or fatal diseases

Which of the following is a characteristic of the skin that influences microbial colonization? A) Low salt concentration B) Acidic pH C) Anaerobic environment D) Extremely moist environment

Acidic pH

Adaptive Immune System

Activated after exposure to a pathogen Highly specific recognition strategies for a specific organism Retains immunological memory for specific organism and response "adapts" with subsequent infections Long lasting protection against a specific disease Only activated when it comes into contact with the pathogen Takes awhile for it to get ramped up (3-5 days) T or B cell that recognizes a certain type of microbe (very specific) Basis of why we get vaccinated (first exposure) so acts faster and bigger response next time it sees that pathogen Rely on randomly generated antigen receptors that can recognize molecules on individual pathogens Multiple genes that contribute to receptors and they can change (millions of receptors) T and B cells have specific receptors (that's why its so slow)

Do Microbes Cause Obesity?

All groups had highly diverse species of microbes present; however, only the obese patient group had a significant population of methanogens Presence of methanogens leads to more efficient digestion

oropharynx microbiota

Staphylococcus (coagulase-neg.) Viridans streptococci neisseria spp.

The hygiene hypothesis postulates that the increase in asthma is caused by what? A) An increase in the presence of pathogenic bacteria B) A decrease in traditional hygiene practices C) An increase in synthetic foods D) A decrease in microbiota diversity

D

Normal Microbiota of the Oral and Nasal Cavities

Common members include -Gram-positive streptococci (e.g., Streptococcus mutans) Lives on your teeth -Anaerobic Fusobacterium spp. below the gumline -Anaerobic Porphyromonas gingivalis deep in plaque deposits Most species are commensals or mutualists but some have pathogenic potential -Dental cavities

Acne

Commonly caused by Propionibacterium acnes, a Gram-positive, rod-shaped diphtheroid commonly found on the skin Every hair follicle has adjacent sebaceous gland (oil gland) Tetracycline (common treatment for people will acne) pH balance

microbial antagonism

Competition of the microbiota with potential pathogens

Treating C. difficile

Current treatment is more antibiotics (most aren't resistant to vancomycin and metronidazole) Potential Treatment: replace natural intestinal flora and naturally outcompete C. difficile

Do probiotics works?

Definitely maybe Effects of probiotics have varied significantly between studies -studies use varying conditions: age of subjects, microbial # and strains Probiotics do provide consistent benefits in people suffering from lactose intolerance or diarrhea due to antibiotic use None of this is proven by FDA

subacute bacterial endocarditis

Dental procedures may permit bacteria to enter blood vessels and be transported to the heart, where they grow vegetations that cause symptoms of this Vegetations - colonies of bacteria

Dermis

Dermis (anaerobic environment) More chance of infection, if your skin gets really dry

Lab analysis of leukocytes

Differential white blood cell count can signal disease: -Increased eosinophils indicate allergies or parasitic worm infection -Bacterial diseases often show increase in leukocytes and neutrophils -Viral infections show increase in lymphocytes

Macrophage

Distributed throughout the body (e.g. alveolar macrophages, Kupffer cells, microglia) Phagocytize pathogens Present antigen to T cells (adaptive immune cell) All over body and have different names depending on which part of the body they are in

Which of the following is NOT a health benefit of the microbiota? A) Compete for nutrients and real estate in the body B) Prevent pathogen colonization C) Synthesize vitamins D) Enhance immunity E) Synthesize food

E- they don't synthesize food

How effective is bacteriotherapy?

Effectiveness of donor feces versus conventional treatment (vancomycin) tested in large scale clinical trial All participants had at least 1 C. difficile relapse Donor feces so successful that study halted early and all participants given donor feces Differences in success with infusion and Vancomycin in C difficile treatment

Benefits of Microflora #3

Enhance function of immune system Germ-free animals have poorly developed immune systems and thin intestinal walls. More susceptible to infection if pathogens introduced. More likely to develop allergies or have immune-mediated diseases Microbiota cause the mucous lining your intestines to be made (protects intestine)

Functions of the gut microbiota

Ferment unused energy substrates (things that body can't digest, they can) Train the immune system Prevent growth of pathogenic bacteria Regulate the development of the gut (helping create mucous lining) Produce vitamins for the host (B, B12, and K) Produce hormones to direct the host to store fats

Physical barrier: stomach

Few microorganisms can survive the highly acidic environment (pH 2-3) Microbes that do survive must have specific defense mechanisms to combat the low pH -Proton pump -Glutamate decarboxylase system -Production of a protective cloud of ammonia -Biofilm formation Ingestion or swallow, most things can't handle going through the stomach Helicobacter pylori - survive stomach creates protective cloud of ammonia that neutralizes the stomach acid

Innate Immune System

First line of defense Immediate response Continuous protection from time of infection to resolution of infection General recognition strategies based on common microbial motifs No"immunological memory" Helps as soon as your infected to when it all gets out of your body Same response as 1st or 2nd or 3rd time even if its same microbe Rely on germ-line encoded, invariant receptors which recognize broad microbe-associated molecular patterns (MAMPs) receptors never change/no variation/recognize broad

Physical barrier: skin

Generally inhospitable to foreign microbes Cool, dry, acidic (pH 5.0) Dead layer of cells on top provides "armor" Desquamation A layer of antimicrobial oil (sebum) & sweat Skin microflora colonize the skin and deter pathogen colonization Difficult to breach; physical disruption (i.e. cut) usually required Epithelial cells (tight junctions) Most outer skin cells are dead so provide dry environment pH from sebum (oil produced from sebaceous glands) As skin cells fall off, so do microbes attached to them Cut or wound is what typically causes an infection on the skin

Group B strep

Group B streptococcus is a common member of the vaginal microflora Often harmless in adults but causes complications to baby exposed during vaginal delivery -Meningitis, pneumonia, bacteremia Any women that is pregnant will be tested in 1 & 3 trimester (some women have it as their normal microbiota) Give you antibiotics before you go into labor if have Group B Strep

H. pylori

Half of population (H pylori) can cause ulcers or stomach cancer (doesn't cause this in everyone) pylori makes an alkaline cloud/buffer around it and attaches to mucous lining

Human Microbiome Project phase 1

Included 242 healthy volunteers, with 15-18 sites swabbed/volunteer for a total of >5,000 samples Conclusions (thus far...): -Microbes contribute more genes needed for human survival than humans' own genome -Microbial metabolic activities are not always performed by the same bacterial species (i.e. activity is more important than the presence of a specific bacterial species) -A human's microbiome changes over time and is affected by disease state and medication but eventually returns to a state of equilibrium -Can't exactly pin point which microbiota is doing good or bad -Drugs, sick, and in time it will go back to equilibrium

Probiotics

Ingestion of living microbes (Yogurt, supplements) Most common probiotic species -Bifidobacterium -Lactobacillus Any sort of fermentation is probiotic Theory: restore balance to microbial community and promote health

Immune system

Integrated system of organs, tissues, cells and cell products that differentiate self and non-self and neutralize potential pathogens No centralized location All over your body (surveillance system)

Physical barrier: mucous

Interior surfaces coated with wet mucus -Mucociliary escalator Mucus contains antimicrobial molecules -Defensin, lysozyme, lactoferrin More infections occur here Epithelial cells (tight junctions) plus a layer of mucous in mucous membranes (acts at trap becus sticky and ciliated cells and protects the cells underneath) Cystic fibrosis, smokers, COPD - break down of mucociliary escalator

Dendritic cell

Located in the lymph nodes and spleen Phagocytize pathogens and present antigen Do similar things as macro Considered an innate immune cell but activates B and T cells

cystic fibrosis or emphysema

Lungs damaged by disease (cystic fibrosis or emphysema) exhibit more diversity and higher numbers of microbes Most of the organisms are pathogenic (Streptococcus pneumoniae, Pseudomonas aeruginosa, Haemophilus influenzae, and Klebsiella pneumoniae)

antimicrobial chemicals in innate immunity

Lysozyme (breaks down cell wall), interferon, complement, defensin (AMPs), iron-binding proteins (lactoferrin & transferrin)

cellular defenses of innate immunity

Macrophages, neutrophils, eosinophils, basophils, mast cells, natural killer cells

Epidermis

Mainly dead cells - epidermis (dry, salty, acidic) not good environment to be there

C. difficile infection

Major risk factor: Antibiotic use Current treatments: Vancomycin and metronidazole (basically more antibiotics) Recurrence rate of infection approximately 20% No highly effective means to treat multiple recurrences Serious issue: incapacitating illness or even death

Vagina microbiota

Most women are colonized with 1-2 species of Lactobacillus, most commonly L. acidophilus, a type of lactic acid bacterium lactobacillus spp. gardnerella vaginalis Candida spp. (Candida (normal microbiota), but change in pH can cause yeast infection) Candida yeast species such as C. albicans are also present, usually at low levels. Overgrowth can cause yeast infections. Neutral pH favors grow of Candida and increases chance of yeast infections -Menopausal women at greater risk due to hormonal changes -Antibiotic use destroys bacterial populations Lacto - lactic acid fermenter (acidic environment in vagina) enables other microorganisms that can't tolerate acid

Physical barrier: mechanical removal

Mucociliary clearance -Cilia sweep mucus + microbes up throat and nasal passages Cough and sneeze reflexes -Removes mucus + trapped microbes Flushing of body fluids -Saliva, perspiration, tears Vomiting and diarrhea -Purges intestinal tract pathogens

Normal microbiota in hosts

Mucous membranes and skin (come into contact with the environment) all the areas that are colonized and act as a barrier to out compete pathogens Some parts of the body are completely sterile (blood, brain, kidneys, heart, etc) Yellow are normal microbiota, but can become opportunistic pathogens Hormones cause increase in oil (propionibacterium) Candida (normal microbiota), but change in pH can cause yeast infection

cystic fibrosis

Mucus becomes very thick and viscous in cystic fibrosis patients, disrupting normal mucociliary escalator clearance of microbes A mutation in chloride transporter (cause waters to stay inside the cell and not let be exported out) causes mucous to become almost like cement (acts like trap but won't be able to be swept away) microbes stay there to cause infection

How do we acquire our microbiota?

Passing through birth canal, first exposure to microorganisms, people are touching the babies after birth so getting microorganisms from people Microbiota passed through breast milk and won't be in formula C-section not gonna have the same flora as baby that come through birth canal (they will eventually catch up)

Human Microbiome Project

Phase One (2007-2014) Phase Two (2014-2016) Funded by the NIH Goals: -Determine whether individuals share a core human microbiome -Understand whether changes in the human microbiome can be correlated with changes in human health (e.g. pregnancy and preterm birth, inflammatory bowel disease, type 2 diabetes) everything in the lab can be taken to treatments rather quickly 1. Catalog of whats the normal microbiota 2. How does that relate to different diseases (preterm birth mostly caused by infection in reproduction)

Blood brain barrier

Physical barriers help keep the microbiota from accessing privileged areas of the body The brain and central nervous system are privileged areas protected by extensive tight junctions between the endothelial cells of capillaries to the brain

Maternofetal (Placental) Barrier

Physical barriers help keep the microbiota from accessing privileged areas of the body The placenta keeps the fetus pathogen-free by separating the maternal and fetal circulations Extensive tight junctions between the capillary endothelial cells of the placenta act as a barrier to most microbes Privilege area Separation of fetal and maternal circulation (has tight junctions like blood brain barrier)

Epithelial layer

Physical barriers help keep the microbiota from accessing privileged areas of the body are held together by tight junctions that act as a molecular "glue" between cells Epithelial cells line the mucosa of our digestive, genitourinary, and respiratory tracts Layer on external surface (skin/epidermis) on skin, blood vessels Sewn tougher by tight junctions that holds cells together (holds like glue) blood-brain barrier has even tighter junctions

thymus

Primary lymphoid organ where T cells are "educated" and deleted if self-reactive. Thymus above the heart (really large when first born) gets smaller as get older

Benefits of Microflora #2

Provide nutrients/vitamins Provide vitamin B12 (only synthesized by bacteria) and vitamin K Provide 5-10% of caloric intake Gut flora or taking it in a capsule Helping making your digestion more efficient (cellulose in plants that we can't digest) getting more out of your food because of microflora Experiment: Look at food consumption/body fat in 3 groups of mice (Mice with microflora ate less but gained more weight even when microflora present in gut for only 2 weeks) GF=Germ free Conv-R=normally colonized mice Conv-D=colonized only for 2 weeks Conv-D - Germ free but given microbiota flora from Conv-R

lymph nodes

Secondary lymphoid organs positioned throughout the body; connected by lymphatic vessels. Site at which immune cells sample lymph and generate an immune response if foreign substance is detected. Similar immune function as lymph nodes; additional function of blood filtration

Bone marrow

Site of hematopoiesis (blood cell formation/differentiation); site where B cells mature in all bones

Ear microbiota

Staphylococcus (coagulase-neg.)

Nose microbiota

Staphylococcus (coagulase-neg.)

Skin microbiota

Staphylococcus (coagulase-neg.) S. aureus Propionibacterium acnes (Hormones cause increase in oil (propionibacterium)) Yeast (Malassezia) Bacteria (Staphylococcus, Micrococcus, and diphtheroids) Gram-positive phyla most common because they tend to be more resistant to salt and dryness Gram (-) outer membrane more susceptible to dry out than cell wall

Gnotobiology

Studies done on germ-free (sterile) animals or those who have been selectively colonized with specific microbes. Germ-free animals have poorly developed immune systems, are more susceptible to infection, and have thin intestinal walls Developed in 1960s

oropharynx

The area between the soft palate and the upper edge of the epiglottis Oral - mouth, teeth, tongue, gums Pharynx divides into larynx (respiratory system) or esophagus (digestive system)

nasopharynx

The area from the nose to oral cavity

Normal Microbiota of the Skin

The average human adult has over 2 square meters of skin (epidermis) populated by 1012 microorganisms. Areas may be dry, moist, salty, or acidic Oil glands and hair follicles provide anaerobic environment Dry areas of skin show most diversity in microbes. Dominance of a particular genera can vary depending on the site sampled Skin microbiota consists of normally harmless microbes that compete with potential pathogens for nutrients and space Cannot be completely removed through cleansing Waste products cause body odor Bacteria in moist environments will break down metabolites (body odor)

Normal Microbiota of the Respiratory Tract

The upper respiratory tract contains numerous microbes (Staphylococcus spp., Haemophilus spp., Streptococcus spp.) Once believed to be sterile, the trachea and bronchi are now known to contain low numbers of normal microbiota Microorganisms that make it into the trachea are trapped by mucus produced by the ciliated lining of the airway The ciliated mucous lining of the trachea, bronchi, and bronchioles makes up the mucociliary escalator, which sweeps foreign particles up and out of the lungs Mucous protects epithelium cells

overgrowth of candida albicans (fungus)

Vaginal yeast infection Thrush Heavy duty antibiotics can cause yeast infections or thrush (candida is fungus so not affected)

3rd line of defense in the immune system

adaptive immune system (macrophage recognizes the LPS on Gram neg (specific bacterial species) B and T cells (cell to cell contact (T) or antibodies (B) cells lymphocytes and antibodies Interplay between innate and adaptive immune system

large intestine microbiota

bacteroides spp. fusobacterium spp. escherichia coli proteus spp. klebsiella spp. peptostreptococcus spp. enterococcus spp.

Mutualism

both species benefit E Coli produces vitamin K (mutualism)

Clostridium difficile

causes pseudomembranous colitis of colon -Anaerobic bacteria found in intestine -Part of normal flora -Overgrowth damages epithelial surfaces -Diarrhea, cramping Extremely painful (diarrhea and cramping) CDIF (heavy antibiotics which is resistant to most antibiotics) releases antibiotics

Disbiosis

change in microbiota that is linked to diabetes, cardiac disease, etc (can lead to stress, autism, etc)

Desquamation

dead skin constantly sloughing off

Hygiene Hypothesis

exposure to microbes (pathogens and commensal species) decreases susceptibility to allergic diseases little exposed to microbes, so we become more susceptible (western cultures)

interstitial fluid

fluid from blood that leaves blood vessels and collects in tissue Plasma that leaves the blood is known as interstitial fluid (fluid in blood is plasma) Picks up debris thats in the tissue (reenters the capillaries on venus side)

Where to get a vibrant, natural, population of intestinal flora?

for C difficile Take healthy donor and take flora and take (other things) to get it into the intestines Problems: -We do not know exact consistency of natural intestinal flora -We cannot culture most of it anyway Fecal bacteriotherapy Fecal enema treatment Nasogastral tube

colon

gastrointestinal tract slightly acidic Most hospitable is colon

Jejunum

gastrointestinal tract (small intestine) Slightly alkaline from secretions of the pancreas and gall bladder (bile)

symbiont

has developed a long-standing relationship with another organism (symbiosis)

Intestinal lumen

has one of highest densities of microorganisms of any known habitat. ~1011 - 1013 bacterial cells/gram feces Accounts for approximately 1 kg of human weight!

Stomach microbiota

helicobacter spp. (H. pylori) Stomach contents are acidic, which is lethal to bacteria The mucous lining of the stomach is less acidic and supports the growth of Helicobacter pylori H. pylori may incite inflammation of the stomach epithelium, causing gastritis or gastric ulcers 1 or 2 pH in stomach Malnourished people have less acidic stomach environment

Langerhans cells

in skin (specialized dendritic cells) can phagocytize microbes Leave the skin (engulf microbe through phagocytosis) and go to the lymph nodes to create an immune response

Eosinophils

innate immune cell (2-4% of leukocytes) Release chemicals that paralyze and digest extracellular pathogens, primarily helminths Release vasoactive agents that dilate vessels and increase permeability of vessels Relatively rare Taking care of really large extracellular pathogens (like worms) release enzymes that paralyze worm and then digest it Asthma and allergies (in western)

Monocytes

innate immune cell (3-8% of leukocytes) Circulate in the blood Differentiate into macrophages and dendritic cells Only found in blood

Neutrophils

innate immune cell (60-70% of leukocytes) Engulf microbes by phagocytosis Release reactive oxygen species Phagocytosis First responder in innate immune system

1st line of defense in the immune system

innate immunity skin, mucous membranes, chemicals Physical and chemical defenses

Lymph

interstitial fluid that enters lymphatic vessels; any pathogens, cellular debris, and foreign materials found in the tissues become incorporated into lymph Stuff that doesn't end up in the capillaries end up in the lymphatic vessel (fluid becomes lymph when it enters the lymphatic vessel) Moves through green and stops at lymph nodes (throughout body, but concentrated at different places) Phagocytic cells, B and T cells in lymph nodes (adaptive cells) T and B cells in spleen Can also filter blood

Supraorganism

is a collection of organisms that function as a single unit with enhanced function Human + microbiota

Normal microbiota

is also termed normal flora and indigenous microbiota Organisms that colonize the body's surfaces without normally causing disease Microbiota aids in digestion, general mental health

Mucosa-associated lymphoid tissue (MALT)

is present at all mucosal surfaces

Gut-associated lymphoid tissue (GALT)

is specific to the GI tract and includes tonsils, adenoids, and Peyer's patches -Peyer's patches are present in the distal small intestine and sample the microbes present there Small intestine (peyers patches) tonsils and adenoids (purple has B, T, phagocytize cells)

small intestine microbiota

lactobacillus spp. bacteroides spp. enterococcus spp.

symbiosis

means "to live together"

Mucociliary escalator

moves mucus and entrapped particles out of passages (ex: respiratory tract, vagina) Increased risk of infection when not functioning (ex: cystic fibrosis patients, smokers)

Resident microbiota

normal microbiota fairly stable (constant flux but fairly stable) Part of the normal microbiota throughout life Most reside in a commensal relationship with the host; some provide benefits (mutualism) or at times can cause harm (parasitism)

Transcient microbiota

normal microbiota passing through (inhale and ingest, but pass through body) Remain in the body for a short period of time Found in the same regions as resident microbiota Cannot persist in the body -Competition from other microorganisms -Elimination by the body's defense cells -Chemical or physical changes in the body Inhabit the same regions of the body as resident, but not able to persist (can't out compete, more susceptible to immune, etc)

Parasitism

one species benefits and the other is harmed E Coli is somewhere its not supposed too (parasitism)

Commensalism

one species benefits and the other is unaffected microbe is benefiting & nothing happens to human We get vitamin K through food so won't need the E Coli to make (commensalism)

gingivitis

plaque build up -Plaque buildup can also lead to gingivitis (inflammation of the gums). -Roots of teeth become exposed. -Bone recedes Teeth is vascular (lots of blood vessels) so that means organisms can get into blood and go everywhere in your body

cavity formation

plaque buildup Microbial communities can form and secrete extracellular matrix forming plaque protecting the microbial community beneath Streptococcal species such as S. mutans ferment sugars and produce lactic acid Acid demineralizes tooth creating a hole (cavity) in the surface Able to attach to teeth, takes sugars from food we eat, and ferments sugars that turns into acid (acid causes demineralization of enamel and get into interior of tooth) Plaque- tartar

Skin-associated lymphoid tissue (SALT)

recognizes microbes that may slip past the physical barrier

Yeast (Malassezia)

skin microbiota produce lipases that break down the oils on the skin into free fatty acids for consumption. Different species have been associated with dandruff, psoriasis and other skin conditions.

Ileum and cecum

small intestine Slightly acidic, less bile