Microbio Quiz 5

microbiome

All sites on a human that contain microorganisms a functional collection of different microbes in a particular environmental system There are approximately 1013 microbes in the human microbiome living in complex communities.

Urogenital Tracts and Their Microbes

Altered conditions can cause potential pathogens in the urethra (such as Escherichia coli and Proteus mirabilis) to multiply and cause disease. E. coli and P. mirabilis frequently cause urinary tract infections in women. Microbial growth in the urogenital tracts. Glycogen fermentation produces acid and encourages the growth of bacteria, like lactobacillus acidophilus. After menopause glycogen production stops and the microbiome of the vagina reverts to a near-prebucent state. Glycogen gets fermented, discourages growth of staph auereus TSS is very rare, caused by staph auereus. Acid produced by glycogen fermentation blocks___. Lactobacilis acidophilus The vagina of the adult female is weakly acidic and contains significant amounts of glycogen. Lactobacillus acidophilus, a resident organism in the vagina, ferments the glycogen, producing lactic acid. Lactic acid maintains a local acidic environment. Only between puberty and menopause After menopause, the uti rate increases Elderly are immunocompromised Uti's in elderly look like a stroke

examples of capsules

B. Anthrasis uses its capsule to adhere to host tissue. Pathogenic E. coli use their capsules to stick to intestinal pili.

Neurological Exotoxins:

Botulinum and Tetanus Toxins Clostridium tetani and Clostridium botulinum produce potent AB exotoxins that affect nervous tissue. both caused by clostridium bacteria both lead to paralysis Botulinum toxin consists of several related AB toxins that are the most potent biological toxins known. Tetanus toxin is also an AB protein neurotoxin.

chocolate agar

Chocolate Agar - Grows fastidious organisms that lack hemolytic toxins Haemophilus influenzae will only grow on blood agar as a symbiote of other organisms that are hemolytic (compromise membrane of RBC)

Inflammatory Bowel Disease (IBD)

Chronic inflammation of the gut and disruption of homeostasis (dysbiosis). Antibiotic use increases the risk of developing IBD. cluster of diseases Once developed, IBD may be transmissible between family members. Individuals with IBD have lower gut microbiome diversity. Reduced functional capacity of the gut microbiome of patients with inflammatory bowel disease compared to healthy subjects

Colonization, Succession, and Stability of the Gut Microbiota

Colonization begins at birth, with transfer from mother to infant. Early colonizing microbes are a source of vitamins and tend to be facultative rather than obligate anaerobes. Variables determine the nature of the gut microbiome. Vaginally born infants have a microbiome more similar to that of their mothers than those born via Cesarean section. Breastfed infants have more commensal bacteria, as breast milk has oligosaccharides that promote their colonization. Early experiences determine gut microbiome. Aging and frailty are associated with decreased microbial diversity.

AB-Type Exotoxins

Diphtheria Exotoxin: Blockage of Protein Synthesis AB toxin that is made up of an Active (A) domain and a binding (B) domain The A domain adds an ADP-ribosyl group to EF-TU, which prevents its function in translation. interferes with ribosome function exit cell to infect host

Endotoxins are very different from Exotoxins

Exo is more targeted Endo are more passive, less toxic, don't elicit a strong immune response, don't cause a systemic response only cause local response. Won't get tss from endo

Acne vulgaris Virulence Factors

Extracellular lipase Hyaluronase adhesins Sialidases hemolysins

Adherence Structures:

Fimbriae, Pili, and Flagella Fimbriae, Flagella, and pili are bacterial cell surface protein structures that function in attachment.

pathogenicity islands

G=-C content of 45% meaning DNA is exogenous i.e. a virus usually G=-C is content is 50%

Haemophilus influenzae

H. influenzae is an opportunistic pathogen. Does not cause flu (flu is caused by virus, not bacteria) Only causes infection until we are immunocompromised Or it cooccurs with s.aureaus bc symbiote of s. aureaus

humans are ___ and ___

Humans are monogastric and omnivorous.

Metagenomic

Humans have coevolved with bacteria Sanger sequencing - pure sample of dna that only has one genetic sequence and you synthesize from one single org at a time (too slow for many genes) Many other kinds of sequencing that are a gene on a bacteria on a single site studying microbiome, looks at all bacteria

Gastrointestinal Microbiota

Intestinal microorganisms carry out a variety of essential metabolic reactions that produce various compounds Firmicutes, Bacteroidetes, and Actinobacteria are common in the gastric fluid, while Firmicutes and Proteobacteria are common in the mucus layer of the stomach. Helicobacter pylori was discovered in the 1980s and has since been found in ~50 percent of the world's population. When present, it is found in the gastric mucosa. Individuals may have mostly Firmicutes, mostly Bacteriodetes, or a mix of the two. This may regulate metabolism and the host's propensity for obesity.

[a] measures how many pathogenic cells are required to kill 50% of the treatment group. A [b] mortality rate of infected individuals would be expected with a low LD50. A [c] mortality rate of infected individuals and a low LD50 would most likely be associated with a [e] organism. [f] is a measure of the death caused by disease. [e1] is a measure of the people with disease or illness and is often a better indicator of how contagious an organism is than its LD50 A highly [g] organism spreads quickly and therefore will have high [h], but might not necessarily lead to high [j]. For example, V. cholerae has a high LD50, and a low mortality rate (especially when treatment for symptoms is available), but spreads very quickly in areas with high population density and no water treatment systems.

LD50 high high, virulent mortality morbidity contagious, morbidity, mortality

Products of Intestinal Microbiota and "Educating" the Immune System

Many microbial metabolites or transformation products that can be generated in the gut have significant influence on host physiology. vitamin production. B12 for vegans modification of steroids amino acid biosynthesis

Respiratory infection

Microbes thrive in the upper respiratory tract. Bacteria continually enter the upper respiratory tract from the air during breathing. Most are trapped in the mucus of the nasal and oral passages and expelled with nasal secretions or swallowed and then killed in the stomach. The lower respiratory tract has no normal microbiota in healthy adults. Ciliated mucosal cells move particles up and out of the lungs. Cystic fibrosis can lead to severe infection in your lungs

The Stomach and Small Intestine

Microbial populations in different areas of the GI tract are influenced by diet and the physical conditions in the area. The acidity of the stomach and the duodenum of the small intestine (~pH 2) prevent many organisms from colonizing the GI tract; however, there is a rich microbiome in the healthy stomach.

Experimental Protocols and Body Target Sites

Most Bacteria cannot be cultured; however, advanced sequencing techniques allow for identification of different microbiota at different body sites. There have been multiple studies to determine the nature of the normal microbiota. There are currently integrated projects underway to answer basic questions about the human microbiome.

The Role of the Gut Microbiota in Obesity:

Normal mice have 40 percent more fat than germ-free mice with the same diet. When germ-free mice were given normal mouse microbiota, they started gaining weight. Mice that are genetically obese have different microbiota than normal mice. Obese mice have more Firmicutes Fermentation by firmicutes would increase caloric value of food consumption but can impact phenotypic presentation VFA - volatile fatty acids Starvation environment with no firmicutes would lead to emaciation Phenotype influenced by microbes inhabiting our intestine Like the mouse model, obese humans have more Firmicutes than non-obese humans. The nature and transferability of gut microbiota is dependent on diet as well genetics

Antibiotics and the Human Microbiome

Oral antibiotics decrease ALL microbes in the human gut (both target and non-target). Use of antibiotics during the first few months of life increases the risk of developing IBD and other disorders related to dysbiosis. Clostridium difficile infections are associated with antibiotic use.

Virulence

Pathogens use various strategies to establish virulence. the relative ability of a pathogen to cause diseases

Prebiotics

Prebiotics are typically carbohydrates that are indigestible by human hosts, but provide nutrition for fermentative gut bacteria. lactoferran

Probiotics

Probiotics are live organisms that confer a health benefit to the host. Species of Bifidobacterium and Lactobacillus (also in vagina) bacteria are commonly used probiotics found in yogurt and probiotic drinks. They may work by taking up space or nutrients, limiting the ability of pathogens to colonize the gut. Examples of some probiotic foods and supplements widely available worldwide. Bifidus regularis- activia- Kimchi, kombucha, miso soup, sauerkraut,

Glycogen fermentation

Selected Answers: lowers pH. produces acid. prohibits the growth of Staphylococcus aureus

The Large Intestine

The colon is essentially an in vivo fermentation vessel, with the microbiota using nutrients derived from the digestion of food. Most organisms are restricted to the lumen of the large intestine, while others are in the mucosal layers.

The human gastrointestinal tract and major members of its microbiota.

The human gastrointestinal (GI) tract consists of: stomach, small intestine, and large intestine; comprises 400 m2 of surface area Responsible for digestion of food, absorption of nutrients, and production of nutrients by the indigenous microbial flora Contains 1013 to 1014 microbial cells

Section through a tooth.

The oral cavity is a complex, heterogeneous microbial habitat. Saliva contains antimicrobial enzymes. But high concentrations of nutrients near surfaces in the mouth promote localized microbial growth. The tooth consists of a mineral matrix (enamel) surrounding living tissue, the dentin, and pulp. Dental carries are somewhat unique in that the pathogens reside on the surface of the tooth and gum and the biproducts of their metabolism contribute to decay. Sucrose enables Streptococcus mutans to produce the thick capsule necessary for adhesion to teeth. After initial contact, Streptococcus sobrinius and Streptococcus mutans attach and reproduce and form a biofilm called plaque. Cells form a biofilm called dental plaque, which has Streptococcus and other fermenting bacteria. Plaque - streptococcus has exoenzymes that trap and digest sugars we consume and form plaque on tooth, our enzymes and saliva calcify plaque to form tartar on tooth These fermenters produce acid, which wears down the tooth enamel. Periodontal disease is thought to contribute to several systemic conditions, including cardiovascular disease and arthritis. apatite mineral makes up teeth - calcium carbonate biofilm has 4 sequential layers! takes about 8 hours, that's why we brush twice a day! extracellular, sits on surface

The Compromised Host

The pathogen-host interaction is dependent upon both the host and the pathogen. Certain medical procedures (e.g., surgery) or underlying conditions predispose individuals to develop diseases. Infections with viruses, such as HIV, weaken the immune system. old people, newborns, organ recipients, autoimmune diseases

The Skin and Its Microbes

There are approximately 1 million resident bacteria per square centimeter of skin for a total of about 1010 skin microorganisms covering the average adult. The skin surface varies greatly in chemical composition and moisture content Skin is its own ecosystem three microenvironments dry skin (most of body) moist skin (sweat) sebaceous skin (oily) Moist and sebaceous skin is most prone to infection

hemolysins

Toxins that lyse red blood cells are called Hemolytic - compromise membrane of RBC

Lethal Dose 50

Virulence can be estimated from experimental studies of the LD50 (lethal dose50). the amount of an agent that kills 50 percent of the animals in a test group Highly virulent pathogens show little difference in the number of cells required to kill 100 percent of the population as compared to 50 percent of the population = low ld50

Gut Enterotypes

While individuals vary in their gut microbiota, each individual has a relatively stable gut microbiota. There are three basic enterotypes currently being studied: #1 is enriched in Bacteroides, #2 is in Prevotella, #3 is enriched in Ruminococcus. Early studies indicate that each enterotype is functionally as well as phylogenetically distinct.

Human Study Groups and Animal Models

While there are significant differences between mice and humans, mice have been used to good effect to study human gut microbiome interactions. Mice have a larger cecum than humans. Most fermentation is completed in the mouse cecum, rather than the human large intestine. Mice have a short life cycle and well-defined genetic lines; they can be raised in a germ-free environment. can control: antibiotic therapy strict dietary control fecal transplants - usually come from someone you live with because you share a similar microbiota germ-free environment Microbiota can influence an organisms physical

Capsules

adherence factor The bacterial capsule forms a thick coating outside the plasma membrane and cell wall and serves two important functions in bacterial pathogenicity. The capsule is both sticky and contains specific receptors to facilitate attachment on host tissues. Capsules, such as those found in Streptococcus pneumoniae, protect the bacteria from ingestion by white blood cells aids in attachment, AND in avoiding host immune response

Virulence factors:

adhesions, capsule layers, can come from cilia, fimbriae, cell structures that confer pathogenicity, come from exogenous dna

Nosocomial infections

affect nearly 2 million people each year. infections you attain at hospital legionnaire's disease - legionella, moist environments, old people, hvac

microbiota

all the microbes in a microhabitat (e.g., skin microbiota). Different microhabitats support different microbes, so the skin will have very different microbes than the mouth. Microbes in gut affect early development, health, and predisposition to disease. Colonization of gut begins at birth.

Coagulase

allows bacteria to hide from host immune system avoids immediate detection by immune system causes clotting

systemic responses

anaphylactic shock, fever,

Infection:

any situation in which a microorganism (not a member of the local flora) is established and growing in a host nonnative microbe is in host not necessarily disease

Opportunistic infections

are those caused by organisms that do not cause disease in healthy hosts. prey on immunocompromised

A strain of a pathogenic bacterium that is missing virulence factors to reduce is virulence and rate of infection would be termed __.

attenuated

Septicemia:

bloodborne systemic infection, may lead to massive inflammation, septic shock, and death sepsis active infection, bacteria making toxins

fluoride in teeth

can replace calcium carbonate making a stronger mineral too much F = brown teeth

Superantigens

cause an overstimulation of the immune system can lead to shock and death (like TSS) generally due to a localized infection, but with systemic effects produced by s.aureaus Releases toxin into blood stream but different from bacteremia Antibody generator, have a systemic response even though it's a localized infection Scalded skin syndrome- infants, bacterial infection, skin behaves like it's scalded, painful Cytokine storm - cell signaling within immune system, superantigens trigger lots of cytokines

pustule acne

cystic acne that hasn't spread, inflamed because of extravasation, rbc are fighting off bacteria, pus making, second worst papule with pus on top

Future Benefits of Knowing the Human Microbiome

development of biomarkers for predicting predisposition to diseases designing targeted therapies personalized drug therapies and probiotics These are very early studies, and they reveal that there are complex interactions between host and its microbiota. Microbiota can be used as a fingerprint!

Hyaluronidase

digest hyaluronic acid (ha) to break down connective tissue between cells can penetrate deeper to an bacteremia and septisemia kybella - use hyaluronidase to break tissue and then freeze fat off

Extracellular lipase

digest skin cells to go deeper into cell and use as food source

streptokinase

dissolves clot so it can go deeper into blood stream

a] is a kind of toxin found in the LPS layer of gram negative bactera. The O-antigen in the LPS layer is the toxic component: it causes an inflammatory response. In contrast, an [b] exits the cell and usually causes damage to host cells or alters their gene expression to benefit the pathogen. For example, the [c] toxin produced by Corynebacterium diphtheriae is released by the bacterium. The [d] subunit of the toxin adheres to the cell and the [e] subunit enters the cell and interferes with protein synthesis. Bacteria can also produce enzymes to help them infect the host. An enzyme called [f] can break down components of skin tissue to enable the bacterium to invade deeper into the host. An enzyme called [g] can help the bacterium digest and break down efforts by the host's immune system to wall off the pathogen and prevent it from spreading. Other bacteria can use an enzyme called [h] to cause components of the host's own cells to adhere to the bacterium's surface in order to avoid detection by the host's immune system.

endotoxin exotoxins AB toxin B A hyaluronidase streptokinase coagulase

Enterotoxins

exotoxins whose activity affects the small intestine generally cause massive secretion of fluid into the intestinal lumen, resulting in vomiting and diarrhea example: cholera toxin

infection process

exposure (lesion) -> adherence -> invasion -> multiplication

Which group of microorganisms is associated with the production of volatile fatty acids (VFA) in the guts of obese mice in a study about the effect of microbiomes on weight gain?

firmucites

Adhesions

glycoproteins on the surface of the pathogen that help them stick to host cell receptors Adherence of pathogens to tissues via receptor molecules on the cell surface. There are many different receptors coating both the pathogen and tissues where the bacteria or virus binds.

Invasiveness

has to get through epithelium of skin and needs to multiply and produce toxins ability of a pathogen to grow in host tissue at densities that inhibit host function

The Human Microbiome Project (HMP)

have formed most of our understanding of the functions of the human microbiome. Surveyed many people, lots of data, can make better predictions surveyed hundreds of medical students over several years to determine a baseline for healthy human microbiomes. Later projects showed the weakness in this model, as they revealed more diversity in non-US born subjects and lacked data on diet or other lifestyle attributes.

Fimbrae

help salmonella attach to cell surfaces can do less than pili can Fimbriae and pili also play a role in adherence of bacteria to host cells Pili are longer and fewer in number than fimbriae help with adhesion i.e.

strep. pneumonia

highly virulent low LD50 -> deadly

Sialidases

host tissue destruction

disease process

infection -> toxicity -> tissue/systemic damage infection -> invasiveness -> tissue/systemic damage

Clostridium difficile

is a spore-former and generally antibiotic resistant. opportunistic pathogen A newer therapy for Clostridium difficile infection is a fecal transplant. c.Difficile is common org but don't present infection bc they're not immunocompromised or have a healthy microbiota and keep the population low. Acne can disrupt microbiota Take probiotic during antibiotic treatment Antibiotic treatment increases the risk of Clostridium difficile infection.

Skin Microbes Composition

is influenced by: environmental factors (e.g., weather) host factors (e.g., age (puberty), personal hygiene) Each microenvironment shows a unique microbiota.

Toxicity

is the ability of an organism to cause disease by means of a toxin that inhibits host cell function or kills host cells.

Microbial Adherence

is the enhanced ability of microbes to attach to host tissues. It is necessary, but not sufficient, to start disease.

Colonization

is the growth of microorganisms after they've gained access to host tissues. The process begins at birth. Typically starts with mucous membranes (intestines, respiratory, genital tract, need to be hydrated and wet), or tightly packed epithelial cells coated in mucus, a thick liquid secretion of glycoproteins

Extravasation

loosens junctions between cells in a blood vessel so wbc squeeze through the gaps

cholera

low virulence highly communicable high LD50 can treat symptoms better than curing

Pathogens

microbial parasites that cause disease, or tissue damage in a host Infection with pathogenic organism is disease Typically starts with mucous membranes (intestines, respiratory, genital tract, need to be hydrated and wet bc microbes can get trapped in them

salmonella

moderately virulent

Which kinds of infections most frequently occur in people with compromised immune systems?

nosocomial

Large intestine

nutrient absorption is slower and has more microbes growing here Vitamin uptake Cellulose makes up fiber (microbes digest through fermentation)

Pathophysiology

physiology of being sick

Cystic acne

pore has infection and buildup, has Hyaluronate lyase, worst kind of acne, leaves deep scars and pits, extravasation damage beneath the skin surface causing multiple papules and pustules to join forming a larger region of infection

botulinum toxin

prevents acetyl coA release muscle never gets to contract flaccid paralysis botox, sweating, migraines

tetanus toxin

prevents release of gabba/glycine muscle never gets to relax

infectious vibrio cholera

prophage

Exotoxins

proteins released from the pathogen cell as it grows. Three categories: AB toxins cytolytic toxins Superantigen toxins

pyogenic

pus causing

Papule acne

pustule that hasn't come to a white head yet.extravasation and vasodilation so it's inflamed, but it hasn't generated pus yet. Still a bacterial infection red and inflamed lump

Infection

situation in which a microorganism is established and growing in a host, whether or not the host is harmed Infection doesn't mean disease

Biofilms on teeth commonly contain the organism [a]. These biofilms can produce acids that accelerate the dissolution of [b], the mineral name for the chemical that makes up teeth. Substitution of hydroxyl groups in this mineral with [c] produce teeth that better resist acid attack.

streptococcus mutans apatite fluoride

Small intestine

takes up nutrient faster because of surface area (pili) and is difficult for microbes to grow here

The release of the neurotransmitter GABA (or glycine) is prevented by the [a] toxin. Without the release of GABA, the nerve continues to release neurotransmitters telling the muscle cell to contract. Therefore, muscle fibers cannot relax resulting in [b]. In contrast, [c] toxin prevents the release of [d], which prevents muscle contraction, resulting in [e].

tetanus spastic paralysis botulinum acetyl coA flaccid paralysis

Pathogenicity

the ability of a parasite to inflict damage on the host

attenuation

the decrease or loss of virulence Attenuated strains of various pathogens are valuable to clinical medicine because they are often used for the production of viral vaccines.

Endotoxin

the lipopolysaccharide portion of the cell envelope of certain gram-negative Bacteria, which is a toxin when solubilized generally less toxic than exotoxins Limulus amoebocyte lysate (LAL) Presence of endotoxin can be detected by the Limulus amoebocyte lysate (LAL) assay. Overharvesting of horseshoe crabs is a concern, as their blood is used in this assay O-antigen triggers immune response

Bacteremia:

the presence of bacteria in the bloodstream

Personal care products touting themselves as organic or natural that contain plant extracts are often more likely to cause an allergic reaction that conventional personal care products.

true

Comedone

white head black head if white head is removed smallest kind of acne no inflammatory response, immunoresponse is not triggered Comedone >> papule >> pustule >> cystic acne Salicylic acid prevents production of comedones

Vasodilation

will increase blood supply by maximizing the diameter

Cytolytic Exotoxins

work by degrading cytoplasmic membrane integrity, causing cell lysis and death hemolysins. Staphylococcal a-toxin kills nucleated cells and lyses erythrocytes Cytolytic Exotoxins (destroy/interfere with host cell mmb integrity)