Medical Bacteriology M4-M7

What is the bacterial ribosome called?

A bacterial ribosome is called a cytoplasmic nucleoprotein and is 70s in size. The are composed of the 50s and 30s subunits.

Describe the symbiotic relationships.

A symbiotic relationship is something between two species in which at least one species benefits.

Which physical characteristics and media/biochemical tests/results can be used to distinguish and identify the Staphylococcus species we discussed?

All the species discussed will be gram positive and catalase positive. The first test that can be used would be the coagulase test this would differentiate S. aureus out of the other two species, S. epidermis and S. saprophyticus. If positive that would mean that the species is S. aureus. If negative a double disk diffusion test can determine whether the species is S. epidermis or S. saprophyticus. S. saprophyticus is novobiocin resistant and therefore the zone of inhibition would be very small to none. S. aureus can also stand out due to the culture on blood agar because it is hemolytic and the other two species are not.

Undefined/complex media

An undefined media is one with complex ingredients relating to that of plants, animals, or yeast and will have a mix of many components of unknown proportions.

1. How are the B and T cells able to confer antigen specificity?

B and T cells also known as lymphocytes are used in either humoral or cell mediated immune response. B cells secrete antibodies like IgA or IgG. We refer to this as IgX. This is effective against extracellular pathogens. T cells work with cell mediated and help deal with infected host cells. They sound the alarm that something is wrong and are effective against intracellular pathogens. B cells and T cells both have recognition/binding of specific antigens due to a complementary receptor. Both B and T cells have variable ends on the antibody that allow for different antigens to bind.

1. Is there a way to prevent these diseases?

B. anthracis can be prevented with vaccinations. There is a vaccination for livestock and one for military personnel. Although, that vaccine can be used on individuals who are around animals and are a higher risk of contracting this bacteria. The livestock vaccine is an unencapsulated live bacillus. The human vaccine is a cell free lysate and recombinant protective antigen. There is protection against B. cereus other than proper food handling.

What are the Babes-Ernst granules and with which group are they associated?

Babes-Ernst granules are associated with C. diphtheriae. When this species is stained with methylene blue the granules will be stained red. They can help distinguish this species from other bacteria with similar characteristics and shape.

1. Indicate the disease associated with each species discussed in the lecture.

Bacillus anthracis has three types of disease associated with it. The first is a cutaneous infection that results in a black eschar. These are skin lesions that will slowly develop raised spots around the initial site of inoculation. Eventually the skin will become black. These can be treated with antibiotics and make a 99% recovery. The spores will germinate in the skin because it is more ideal conditions then the soil. The next disease is gastrointestinal which results from the ingestion of spores. These will germinate in the GI tract and can produce the toxin which can disseminate into the blood stream. This has a higher risk of complications with a 40% risk if left untreated. The last disease would be respiratory related and results from the inhalation of anthrax spores. Once inhaled they will germinate in the respiratory tract and phagocytes will take B. anthracis to the lymph nodes. From here there is a possibility to disseminate to other lymph systems and blood stream. This particular infection is risky because the original symptoms are similar to those of a mild cold. They have fever and fatigue. Although it is rapidly infecting and therefore individuals infected can go into rapid respiratory distress and then death/coma. This would need to be treated at the first phase of fatigue and fever to be effective. The other species associated with disease is Bacillus cereus is food poising and eye infections. The food poising can be found in two types an emetic, vomiting, or diarrheal. These are caused by distinct enterotoxin. The vomiting strain is heat resistant and tends to be prevalent in expressed starch like rice. This will create endospores in the rice which can survive hearting. The endospores will germinate into a vegetative state which will cause toxin production. This will be ingested and within 1-5 hours symptoms will begin to appear. The other strain which is a diarrheal is heat labile/sensitive and generally is the association of ingestion from contaminated meat. Endospores in the intestine to germinate which produce the toxin and will have symptoms within 8 hours. The other disease state that can come from B. cereus is an eye infection which if left underrated can result in blindness.

Know bacterial cell shapes and arrangements

Bacteria size can be from 0.4-4 micrometers. We see that the shapes of bacteria are, coccus, bacillus, spirilla, spirochete, spiral, and mycelia. Each are analyzed a little further by arrangement or rigidity. Coccus is best known for its spherical shape and can come in diplo, strepto, or staphylo. Strepto is a long string of coccus where as staphylo is like a bundle of grapes. Bacillus is a rod shape bacteria. Spirilla is a rigid shape whereas a spirochete is more flexible. Mycelia is filamentous and pleiomorphic, meaning it comes in many shapes and forms.

Differential

Differential media have specific ingredients to be able to distinguish certain species of bacteria based off of visual observations. This can be used to differentiate closely related organisms.

What type of media is bile esculin and which organisms is it used to distinguished between?

Bile esculin is both selective and differential. This type of test will show whether the bacteria is able to hydrolyze esculin in the presence of bile. It can help identify group D Streptococcus and Enterococcus.

Enriched

Enriched usually has a type of growth factor like blood agar.

Who are the members of the CMN group and what do they have in common?

Corynebacterium are members of the CMN group. This group is classified as having coryne-mycolic acid and can assist with desiccation resistance.

Defined/synthetic media

Defined synthetic media is a type of media that is when the components are known. Therefore, there will be known quantities of the ingredients. The synthetic portion relates to the point that chemicals were used to develop this type of media not plants, animal, or yeast tissues.

How is the diphtheria toxin classified and what is its mode of action? Relate this to how it causes respiratory and cutaneous diphtheria.

Diphtheria toxin is classified as an exotoxin. This is encoded by the tox gene which is acquired from bacteriophage. The tox gene expression is controlled by iron. Individuals with high iron will have low tox gene expression where individuals with low iron will have high tox expression. The diphtheria toxin mode of action is to block translation and can cause tissue necrosis. The diphtheria toxin for respiratory infection will cause a pseudomembranous to form this membrane consists of bacteria, fibrin, and dead host cell. This is inherent since the tox gene will cause tissue necrosis or dead cells. In the cutaneous infection we see non-healing ulcer which is also a present sign of dead cells.

Indicate the disease state associated with each of the four organisms discussed.

Disease state for C. diphtheriae include a sore throat and cutaneous infections both generally require antibiotics. The cutaneous infection can cause a non-healing ulcer. A throat infection can lead to a pseudo-membrane forming along with a fever. This does have the potential to dislodge and cause the individual to suffocate. L. monocytogenes can cause pregnant women to spontaneously miscarry. This chance becomes much higher when they consume unpasteurized dairy and cold cuts. This can affect babies that are going to be born or babies in utero. Erysipelothrix rhusiopathaie will affect occupational populations due to exposure. They can develop skin infections that yield purple/red zone known as erysipeloids. Nocardia can cause pulmonary infections like pneumonia and cutaneous infections. For cutaneous infections they can be very destructive to tissue and bone.

1. What are the treatments for the disease states?

Each disease state for B. anthracis could be treated with antibiotics although the most effective would-be cutaneous infections. The least effective would-be respiratory infections unless caught early on. Specific treatment would be penicillin or other beta lactams. Although, certain B. anthracis are beta lactam resistant as they have beta lactamases. Therefore, either ciprofloxacin or doxycycline can target DNA gyrase and be just as effective. Post exposure prophylaxis treatment is used considering the disease states risk to the individuals life. Treatment for B. cereus is limited for food poising. This will generally resolve on its own time, but fluid support may be necessary if the individual becomes dehydrated. For the eye infection antibiotic treatment is necessary can generally is either vancomycin or clindamycin.

What are the key colony morphology characteristics discussed for each Staphylococcus species we discussed?

Each of the Staphylococcus species that we identified shared some colony morphology characteristic. Each had a convex elevation, creamy texture, and smooth surface. S. saprophyticus is smaller in size and generally is white. S. epidermidis is in-between small and medium with either white or gold color. S. aureus is medium in size and can also be white or gold in color. This species is usually gold in color but can be white.

1. Compare and contrast exotoxin and endotoxin.

Exotoxins and endotoxins are large classes. Exotoxin are produced by gram positive and negative bacteria. This usually creates a specific protein, they have specific activity, and secreted or held in cytoplasm. Endotoxins are produced by gram negative bacteria and it is all the same for gram negative bacteria. These make the specific protein lipopolysaccharides, They promote large nonspecific immune response like an inflammatory response, finally they can cause an individual to go into endotoxic shock which can be lethal.

What is the function of pili/fimbriae and what are they composed of?

Fimbriae/pili are hair like protein polymers. The pili works with adhesion, conjugation, and tend to be fewer and longer. Where we see the fimbriae is also used for adhesion and tend to be more but shorter. Both can be used for motility.

1. Indicate their phylum for bacillus

Firmicutes

1. What are the general characteristics associated with this genera bacillus

General characteristics for Bacillus include gram positive, spore forming bacteria that are also nonbranching and catalase positive. The colony morphology will be variable based off of species and media used. They are ubiquitous and are aerobic bacteria and therefore prefer an environment that has 21% oxygen.

Indicate the set of general characteristics for each of the four groups we discussed.

General characteristics for Corynebacterium include being gram positive. Mostly non motile and non-spore forming. They are also catalase positive. We classify them as a facultative anaerobe. They may or may not have a narrow zone of hemolysis. When cultured they have smooth, small, grey/white colonies. These are also included in the CMN group and are desiccation resistant. General characteristic for Listeria include being gram positive this can be variable. They are peritrichous with flagella at 30 degrees Celsius or less. They are also non spore forming. They form small, smooth, translucent colonies with a narrow band of beta hemolysis. They are also a facultative anaerobe. They can also grow at 4 degrees Celsius. General characteristics for Erysipelothrix include being variably gram positive. We see curved bacilli that after incubation periods can grow long filaments. They are non-motile and non-spore forming. The colonies morphology can be in two forms. The first form would be non-hemolytic, smooth, white, convex shaped colonies that are pinpoint size. The second morphology would be small to medium sized, rough, flat, matte, alpha hemolytic colonies. These two differences are dependent on temperature and ph. They are also facultative anaerobes and catalase negative. We see better growth with high carbon dioxide. General characteristics for Nocardia include being gram positive, branched bacilli. They are weak acid-fast bacteria that stain a pink/red in carbolfuchsin. They form colonies on chocolate agar that are chalky, matte, white, crumbly colonies. They have slow growth on culture plates and can take 3-6 days to form colonies. They are catalase positive and aerobic microbe.

Techniques to determine genotype

Genotype of bacteria is how something looks at a nucleotide level. We look at and sequence DNA or genome. We also can analyze the 16s ribosomal RNA which is who the bacteria is related to. Another way to determine genotype is through PCR, polymerase chain reaction, or FISH.

How are the groups of Gram-positive bacilli distinguished?

Gram positive bacilli are distinguished by a couple different factors. The first will be whether they are spore forming. If they are non-spore forming it is determined whether they are branching bacteria. If they are nonbranching we see that we test by catalase test. If positive, we move to a motility test and bile esculin hydrolysis. If negative through the catalase test, we use the H2S production. If the gram-positive bacteria are spore forming another test that can be performed to narrow down the species is the beta hemolytic and if motile.

Know components of Gram positive (monoderm) and Gram negative (diderm) cell envelope

Gram positive cell envelope consists of a thick cell wall. Going from cytoplasm to outside the cell it begins with the plasma membrane that contains hopanoids. Moving up to the periplasmic space which is very small for this type of bacteria. Then comes the cell wall which is thick and contains teichoic acid and lipoteichoic acid. The cell wall is approximately 40 layers. The lipid tail of the lipoteichoic acid is embedded into the plasma membrane which will help anchor it. The teichoic acid helps to keep all the layers together. Gram negative cell envelope from cytoplasm to outside the cell begin with the plasma membrane, next is the periplasmic space and peptidoglycan. The periplasmic space is much larger and includes the cell and runs from the first plasma membrane to the second membrane or outer membrane. The cell wall is very thin on the gram-negative bacteria. There is not teichoic acid in this type of cell envelope. Another characteristic for gram negative cell envelopes is LPS, lipopolysaccharide, there is a region of highly variable O side chain and the conserved core polysaccharide and lipid tail. Both the gram negative and positive cell envelope can have a capsule and S layer but may not have either.

1. Briefly describe what happens in the inflammatory response.

Inflammation occurs when tissues are injured. These damaged cells release histamine/cytokine that assists with vasodilation and can cause redness, swelling, pain, and heat to the area. This release of chemicals will also attract phagocytic cells known as dendrites that help eat away bacteria. Mast cells are assisting with secreting histamine. Eventually there will be a collection of dead tissue, bacteria, and phagocytes and form a pus.

1. Give the major differences between the innate and adaptive immune system.

Innate immunity is something that is already in the body. Adaptive immunity is created in response to exposure to a foreign substance. Innate is a non-specific branch for a given antigen and is immediate and maximal. There is no memory from this branch. The innate branch fights any foreign material in rapid response. The adaptive branch is antigen specific and would recognize antigen presenting cells. There is a lag between exposure and response. We do see memory of the B and T cells. The adaptive branch will only fight specific infections.

1. How might the disease be diagnosed?

Lab diagnostics for Bacillus antrhacis include a culture on a blood agar plate which would result in white/grey, medusa irregular colonies. These are non-hemolytic. They should have a flat, stiff egg white consistency. These are catalase positive and gram positive. We will see bamboo rod shaped on the gram stain which is distinguished by the square ends. They also should have a capsule and a centrally located endospore. This species is non motile. Diagnostics for B. cereus is a culture on a blood agar plate which would show frosted glass like colonies that are hemolytic. This particular species is motile, and the gram stain would be gram positive.

Liquid media

Liquid media is also known as a nutrient broth. Bacteria are able to grow uniformly while producing turbidity. Certain bacteria may grow on the surface of a liquid media.

Selective

Selective media are used for certain microbes. This type of media can have additional factors to prevent certain microbes from growing.

Supportive

Nutrient/supportive media usually has some type of chemical description and can be agar or a soy agar.

1. Which phagocytic cells present antigen to the adaptive branch and in what context?

Phagocytic cells present antigen to the adaptive branch with the use of B cells. We see that clonal expansion of lymphocytes a type of phagocytic cell can yield cells with antigen receptors, B and T cells. Antigen receptors bind to the antigen that is found on the MHC complex. Therefore these are used to assist with infection response.

1. What are some of the key events in phagocytosis and which cells are involved?

Phagocytosis occurs when there is foreign material present in cells. A phagocyte which can be a macrophage, neutrophile or dendritic cell has a receptor known as the C3b receptor. This has the ability to bind to a C3b coated bacterium. On the phagocyte there are other receptors that can bind to bacterium. Phagocytosis does require adaptive or complement system input to occur. The main process of phagocytosis is that the plasma membrane entraps the particle, a vacuole forms within the cell to contain it, lysosomes fuse the vacuole, and the enzymes of the lysosome will digest the food particle.

Phenotypic characteristics of bacteria

Phenotypic characteristics of bacteria relate to how something looks and the physical characteristics. We can identify the phenotypic characteristics of bacteria by looking at the colony morphology, cell shape/arrangement, or cell envelope structure. Some specific colony morphology would include the size, color, pigment, form, elevation, surface, density, etc. We also identify that metabolic pathways and how bacteria behave to biochemical tests are phenotypically categorized. Finally, serology which is the reaction to an antibody would be underneath a phenotypic characteristic.

What is the approximate size of plasmids and what sort of genetic information do they contain?

Plasmids are 2-5mB and they store what is called luxury functions. The circular bacterial chromosome house the essential genes for survival. Where we see the plasmid, housing functions like antibiotic resistance.

What is a sequelae? What are the sequelae associated with Streptococcus pyogenes? What virulence factor contributes to these sequelae?

Sequelae is a condition which is the consequence from a previous disease. The sequelae with Streptococcus pyogenes is glomerulonephritis and rheumatic fever. The virulence factors that contribute to these are DNase which chew up DNA of neutrophils which yield an extracellular trap. Hyaluronic acid capsule which look like our tissue. Cytolysin oxygen stable, not immunogenic .

Give the major bacteria found at each body site.

Skin - slightly acidic conditions around a pH of 5 and a slightly lower temperature then 37 Celsius it also is dry conditions. The bacteria found here are gram positive and Staphylococcus epidermis, Micrococcus, Diphtheroid, Propino bacteria. Respiratory tract, upper - mouth is moist and has lots of nutrients this is where we see Streptococcus viridians and frequently obligate anaerobes. Whereas we see Streptococcus aureus in the nose. In the nasopharynx we see Streptococcus viridians and Dipalithroid. In the oropharynx we see Streptococcus viridians. Respiratory tract, lower - there will be no bacteria there it is a sterile environment. Gastrointestinal tract - In the oesophagus there is only transient bacteria here and no natural residence. In the stomach we see Heliobacter pylori and Lactobacillus. The small intestine houses the same as the large intestine but with fewer bacteria. The large intestine/colon has mainly anaerobes and enteric like E.coli. Genitourinary tract - In the anterior urethra there are the same bacteria s the skin. In the vagina that are Lactobacillus and Strep agalactia. In the upper urethra and the bladder, it should be sterile.

Solid media

Solid media contains agar or an inert solidifying agent. This is something that would allow bacteria to grown in a informative way.

How does being "tough" generally contribute to the mode of transmission for Staphylococcus?

Staphylococcus have to be tough because they are found in areas of the body that can be dry, warm, and having a lot of mobility around them. They are found on the skin which more hostile environment then other areas of the body. Therefore, they make it easier to transmit too. Staphylococcus is found on areas of the body that constantly in contact with other people or equipment meaning they are able to leave the body and live on surfaces to be transferred to someone else easier than a bacteria that is fastidious.

Which disease is each Staphylococcus species associated and how do their virulence factors contribute to disease?

Staphylococcus saprophyticus is associated with urinary tract infections. We see that it affects young healthy women between 17-24 and those who are sexually active. This particular species of Staphylococcus has low pathogenicity, and this is why we see this in a specific subset of people. Staphylococcus epidermis forms biofilms easily and this is why we see this species infecting hospital patients that have catheters. They develop UTI from catheter placement. This species is also of low pathogenicity and another reason why this only occurs in a low subset of people. Staphylococcus aureus and has the potential to have high virulence but does depend on the conditions. This particular type of Staphylococcus can cause folliculitis, furuncle/boil, and carbuncle. These all relating to the skin from least to most serious. They can also cause infections with exfoliative toxins. These include scaled skin syndrome and bullous impetigo. This can also cause more serious issues that can lead to shock like toxic shock syndrome or food poising (only if inhaled in larger quantities will it lead to shock). We see that S. aureus causes a variety of disease because it has the possibility to be more virulent.

Indicate the reservoir for each Staphylococcus species we discussed?

Staphylococcus saprophyticus is found in the GI tract. Staphylococcus epidermis is found through urinary catheter placement due to the biofilm that builds. Staphylococcus aureus is found on the skin and mucus membranes.

From which genus does the catalase reaction distinguish Staphylococcus?

Staphylococcus will be catalase positive compared to that of Streptococcus which will present as catalase negative.

Biovar

Variant prokaryotic strain that differs physiologically from other strains in a particular species. Bacteria with identical genetic makeup but different biochemical or physiological characters.

What characteristics (e.g., cell shape) and other test results could be used to distinguish two pathogens we discussed that cause sore throats? Remember the case study!

Streptococcus pyogenes causes strep throat and Corynebacterium diphtheriae causes a sore throat with the addition of a pseudo membrane. S. pyogenes has the following characteristics they are gram positive and catalase negative cocci shaped bacteria. They have the ability to form chains. The colony morphology is small, smooth, translucent colonies. They do hard beta hemolysis. The following test results are indicative of S. pyogenes a throat culture taken from an individual with a sore throat would show the colony morphology stated above. The other test used would be a sulfamethoxazole trimethoprim disk that would differentiate this species from other Streptococcus species. If the BAP plate has a zone of inhibition it would be S. pyogenes. Corynebacterium are also gram positive but are catalase positive. This would be one test that could help differentiate between the two. The colony morphology is similar to S. pyogenes we see small, smooth, grey/white colonies. With or without a narrow zone of hemolysis. A tellurite blood agar plate can be used to identify C. diphtheriae. It is a selective differential plate where the tellurite prevents most other bacteria from growing. We would observe a tins dale halo if it were to be C. diphtheriae. Along with the presence of a pseudo membrane the two could be differentiate from one another.

What is the average size of the bacterial chromosome?

The average size of the bacterial chromosome is 2-5 mB but can range from 1-13mB.

Bacterial taxa discussed in class, most general to specific

The bacterial taxa discussed in class from most general to specific is as follows. Domain, kingdom, phylum, class, order, genus, and species. Species can be broken down into subspecies, strain, serovar, or biovar.

1. What is the basis for attachment during enhanced and unenhanced attachment?

The basis for attachment during enhanced is opsonization which uses IgG. They can also use complement C3b. The basis for attachment in unenhanced is PAMP which is done by teichoic acid or LPS.

What is the basis for the Lancefield reaction? What is the Lancefield reaction for S. pyogenes, S. agalactiae, S. pneumoniae?

The basis for the Lancefield reaction is to classify Streptococci into a group that is based on the presence of polysaccharide and teichoic acid in the cell wall. The classification will give a letter to each group. One can test for the Lancefield reaction is through the slide agglutination test which allows for reactions of specific species of Streptococcus to react with different antibodies. The Lancefield reaction for: S. pyogenes is group A. S. agalactiae is group B. S. pneumoniae does not have a group classification.

What is the cell, shape, arrangment, and size of typical Staphylococcus

The cell shape is coccus, which is a spherical shape, and is usually seen arranged in clusters. the typical size is 0.5-1 micrometer

1. Which cell types are involved in the humoral and cell mediated response of the adaptive branch of the immune system and what do they do?

The cell types involved in humoral response of the adaptive branch of the immune system are B cells. B cells will secrete antibodies and effective against extracellular pathogens. They can mark cells for destruction by other immune cells. Cell mediated response of the adaptive branch of the immune system uses T cells. T cells are broken into two different categories, T helper and T cytotoxic. T cells will sound the alarm that there is infected cell. These are effective against intracellular pathogens. T cells work with more foreign material than B cells and create an immune attack. Whereas we see B cells producing and binding bacteria in order to prevent cells from binding. We do see T helper cells activating B cells.

Where does the diphtheria toxin come from and how is its expression regulated? Should it be on or off in a host and why?

The diphtheria toxin comes from the tox gene expression. This is acquired from a bacteriophage and is controlled by the amount of iron present. A low iron content will have an increase of tox gene expression in the host. When there is a high iron content, we see a low tox gene expression.

Which of the four species we discussed has the pinpoint colonies?

The four species we discussed that have pinpoint colonies are Erysipelothrix rhusiopathiae, Listeria monocytogenes, and Corynebacterium diphtheriae.

Functional types of media

The functional types of media are nutrient/supportive, enriched, selective, differential, and transport. Transport media is used to support vitality and not growth. This is used when an organisms needs to be transport possibly in the hospital setting.

Indicate general key features of the Streptococcus—that distinguish them from Staphylococcus.

The key features of Streptococcus are gram positive and are coccus in shape. They are chains of coccus shaped bacteria. They are nonmotile and non-spore forming. Streptococcus does not grow as well as Staphylococcus does on supportive media. Streptococcus bacteria are aerotolerant anaerobes and mainly will perform fermentation. They are also catalase negative. We see the similarities between Streptococcus and Staphylococcus because they are both gram positive coccus shaped bacteria. Although, Staphylococcus are catalase positive and are more facultative anaerobe and therefore can be more tolerant of oxygen.

1. Indicate the major routes of transmission.

The major routes of transmission are airborne which involves respiratory secretions, and we see Mycobacterium tuberculosis being spread through this. Another route of transmission is food and water which is done through ingestion and tends to affect the gastrointestinal tract. E. coli and V. cholera are two examples that can be seen from this route of transmission. Close contact is a transmission that generally will give individuals STD and will usually have fastidious bacteria that have trouble living elsewhere on the body and this is why close contact is important. Cuts are another route of transmission these generally come from animals. We see cat bit and scratches to cause cat scratch fever. Arthropods are another route of transmission in which the bacteria survive and grow in the arthropod and are transferred to us when they bite. The last route of transmission is zoonoses which is bacterial disease transmitted from animals to humans.

What is the microbiota and where do we get it?

The microbiota is microbes that live in and on us. There are roughly 10^14 microbes on us which outnumber the amount of eukaryotic cells that we have. We can have normal, indigenous, usual, resident microflora that is common to a specific body site. There is also transient flora is a temporary infection eliminated by hose defense or resident flora out competes them.

What are the reservoirs for the four groups of bacteria discussed in this first part of chapter 16 (i.e., not the Bacillus)?

The non-spore forming, nonbranching, catalase positive bacilli Corynebacterium reservoirs is the skin in humans. The reservoir for Listeria is the soil/water. The non-branching, non-spore forming, catalase negative bacilli, Erysipelothrix has the reservoirs as swine but can also be other vertebrates or invertebrates. The non-spore forming, branching, aerobic Nocardia reservoirs can be plants or in the air.

What is the oxygen usage description and catalase reaction for members of the Staphylococcus genus?

The oxygen usage description is that they are facultative anaerobes. This means that they like to be in 21% oxygen but can deal with lower amounts or no oxygen. They are catalase positive. This means that they contain an enzyme that allows the breakdown of hydrogen peroxide to water and oxygen.

Indicate the phylum for each.

The phylum for Corynebacterium is Actinobacteria. The phylum for Listeria is firmicutes. The phylum for Erysipelothrix is firmicutes. The phylum for Nocardia is actinobacteria.

To which phylum do Staphylococcus belong and what are the major characteristics of this phylum?

The phylum that Staphylococcus belong to are firmicutes. The major characteristic of this phylum are that they can be gram positive and with a low G-C content.

What are the physiological classifications of the Gram positive, catalase negative coccus?

The physiological classifications of pyogenic Streptococcus is that they are pus producing, normal flora of the mouth throat and skin. They are also mostly beta hemolytic and non-viridians. The viridians Streptococcus for normal flora of the upper respiratory tract. Mostly alpha hemolytic and many lack the c-carbohydrate. The enterococci are normal flora of the GI tract. They are gamma and non-hemolytic mainly but there are versions that are alpha and very small amounts that are beta. Sometimes they are group D of Lancefield and are hardy and tough. Lactococcus are homo-fermenter of lactic acid and non-hemolytic along with being group N.

What is a unique component of the acid-fast cell envelope?

The unique component of acid-fast cell envelope is the mycolic acid. Acid fast cell envelopes are very similar to that of the gram-positive cell but with the addition of mycolic acid. This contribution makes a waxy component which helps bacteria from drying out, desiccation. This type of bacteria is hard for stain to get into the cell and hard for it to come out. Therefore, if you were to put a cell that is acid fast into the right stain it will become red whereas gram positive and negative cells will not have any color.

What vaccine provides protection against diphtheria?

The vaccine that provides protection against diphtheria is DTaP. It uses formaldehyde to denature the diphtheria protein and therefore the individual receiving the vaccine does not received a live bacteria.

1. What are the virulence factors associated with each species and how do they function to promote the disease state?

The virulence factors for B. anthracis have two major ones the first will be the capsule. This can block phagocytosis and are not recognized by host proteases. The capsule is made of a polypeptide D-glutamic acid. It is encoded by the plasmid gene POX2. This capsule is necessary to infect individuals. The next virulence factor is the anthrax toxin which has three proteins involved. The first is the protective antigen which will bind anthrax toxin receptor in most cells. The next would be the lethal factor which is a metalloprotease which will target map kinase and help the edema factor. These will trigger cell death and the breakdown of the epithelial layers. The last factor is the edema factor which causes ATP to cAMP. This is inappropriately done and disrupts cell signaling, ion flow, and water flow. This will cause fluid accumulation in the tissue. The virulence factors for B. cereus is that the food poising disease is heat resistant.

Listeria is a facultative intracellular pathogen. What are the virulence factors associated with Listeria monocytogenes and how do they promote the intracellular lifestyle?

The virulence factors that are associated with Listeria monocytogenes include factors that help intracellular movement. The first will be internalin which has proteins InlA and InlB which are surface proteins that promote phagocytosis by the host cell. Next would be listeriolysin O which lyse phagosome/endosome escape to cytoplasm of host cell. Finally act A is a surface protein that can polymerize hose actin, allowing intracellular movement and between host cells. All of these will work in conjunction to assist with intracellular movement. The intracellular movement is good for the bacteria because it becomes difficult for pregnant women immune system to help protect babies in the uterus.

1. What are the barriers to infection and how do they function?

There are four barriers to infection, skin, mucous membranes, cleansing actions, and stomach acid. Skin is a mechanical barriers that is desquamation and has keratin which is a bad food source. The mucous membranes contain epithelial cells covered in mucoid which would trap bacteria preventing them from infecting. The cleaning action of tears and urine can act as microbials with the help of sIgA. They also have lysozymes and the presence of lactoferrin all preventing bacterial infection. The stomach acid is at a low pH. A low pH helps control the amount of microbial activity in the body. For example, Vibrio cholera is a disease that is controlled with a low pH, if your body were to raise the pH risk of increasing this bacteria would be high.

Provide definitions for relationship associated terms.

There are four types of symbiotic relationships, mutualism, commensalism, parasitism, and carrier. Mutualism is when both organisms will benefit from relationship. We see this type of relationship with lactobacillus in the vagina. Due to the pH no other pathogens can grow that would harm lactobacillus. Commensalism is when bacteria will benefit, and the host is unhurt. Parasitism is when the bacteria benefit, and the host is hurt. An example of this is vibrio cholera where it changes the host ion flow in the intestines causing watery diarrhea. Finally, carrier is the type of relationship where a host is infected with a disease-causing bacteria without the disease effects. This host will then spread infection. An example of this was Typhoid Mary who had salmonella typhi and infected the people she cooked for.

Colony morphology characteristics and what they indicate (e.g., density refers to light passage through a colony, transparent, translucent or opaque)

There are multiple aspects analyzed when looking at colony morphology; size, color, form, elevation, surface, density, consistency, and odor. Colony size is analyzed by three general sizes, pinpoint, small/medium, or large. Color is general for the genus and usually indicates a specific genus. Whereas pigment can be more specific for species. Form indicates each colony looks like there are four types; filamentous, smooth, irregular, and rough. Elevation is looked at by tilting the agar plate at an angle to view the height of the colony. For this we can describe them as flat, convex, umbilicate, raise, or umbonate. Surface is analyzing what the surface texture looks like. Density is how well light is transmitted through the colony. Consistency is done by taking an inoculation loop and touching the colony. Finally, odor is a analyzed and seen how it smells.

Define all of the gaseous air descriptions (e.g., aerobic)

There are multiple types of gaseous air descriptions all below; Obligate aerobe which prefers 21% oxygen environment which is like the atmosphere. Facultative anaerobe which prefers like 21% oxygen, but it is not required. Aerobe tolerant which prefers to not use oxygen but can tolerate it. Microaerophile which like less then 21% but prefers 5-10% concentration Obligate anaerobe will not use oxygen and cannot tolerate it Capnophile requires increased carbon dioxide concentration between 5-10%

Indicate the nutritional growth descriptions and what they mean.

There are three general nutritional descriptions, carbon source, energy source, and electron source. Carbon source has autotrophs and heterotrophs. Autotrophs gain energy from carbon dioxide and heterotrophs use organic molecules. Energy sources can by phototrophs and chemotrophs. This is where bacteria fall. Phototrophs gain energy from the sun and chemotrophs gain energy from oxidation chemicals. The final nutritional growth is the electron source. This comes in organotroph or lithotroph. Organotroph gains electron from organic molecules and the lithotroph gains electrons from inorganic molecules.

1. What are the hemolysis types and which to you associate with S. pyogenes, S. agalactiae, S. pneumoniae and Enterococcus?

There are three hemolysis types alpha, beta, and gamma hemolytic. Alpha hemolytic results with a green/brown oxidation of hemoglobin to methemoglobin and results in the color change and very little halo effect. The beta hemolytic is the complete hemolysis and we see this bacteria secreting hemolysins therefore it is no longer red around the cultured bacteria. Non hemolytic is referred to as gamma hemolytic which is no hemolysis and there will be redness present all the way up to the bacteria. There is also something known as alpha prime hemolytic which is a thin zone of red blood cells and then hemolysin. S. pyogenes are beta hemolytic S. agalactiae are beta hemolytic S. pneumoniae are alpha hemolytic Enterococcus are mainly non hemolytic (gamma) but can be alpha>beta

What are the surface polymers and what are they composed of?

There are two surface polymers, the capsule and the S-layer or slime layer. The capsule and slime layer are similar to one another. The capsule is made with polysaccharides or polypeptides. Whereas the slime layer is a polymer of polysaccharides or peptides. The difference between the two include the difficulty to remove. The capsule is much harder to remove. The slime layer is easier to remove and less organized. We also see that the slime layer has a monotypic glycoprotein.

1. What happens when these B and T cells are activated?

There are two types of T cells, the T helper and T cytotoxic. T helper cells, Th, become activated through the MCH II complex due to the binding of CD4. This binding causes the cells to release cytokines and this will yield the T cell to clone itself or do what is called clonal expansion. There are two different things than occur from this. The first being the production of Th memory cells and the other is an effector cell which can activate B cells or macrophages. In T cytotoxic cells, Tc, interacts with the MCH-I complex it will activate the cells. This type of cell will be binding to an infected cell. They will release perforins and help to break down the infected cell. The Tc cell will perform clonal expansion and produce Tc memory cells. In B cells they can be activated by a T helper cell, from the above process, and will bind to an antigen. Clonal expansion of B cells will occur yielding memory cells and plasma cells. They can be differentiated after the process of clonal expansion.

Is there currently an approved vaccine against Staphylococcus aureus?

There is not an approved vaccine against S. aureus.

Semi-solid media

This type of media is used to show bacteria motility and is able to differentiate motile and non-motile strains. These are a soft media.

Serovar

Variant prokaryotic strain that differs physiologically from other strains in a particular species. Bacteria with identical genetic makeup but different biochemical or physiological characters.

For each of S. pyogenes, S. agalactiae, S. pneumoniae and Enterococcus indicate:

a. Common reservoir (where you find them) S. pyogenes: They are found on the skin and in the throat. S. agalactiae: Found in the genital tract, skin and throat. S. pneumoniae: They are found in the nasopharynx with 40-70% carriage. Enterococcus: Found in the GI tract. b. Distinguishing characteristics and tests with results that may be used for diagnosis S. pyogenes: They are gram positive coccus chains and are 0.5-1 micrometer. They are smooth, small, and translucent when plated on BAP. They are beta hemolytic. Testing that is used to identify this is cultures. Along with a bacitracin disk susceptibility test which will help differentiate between other beta hemolytic species. S. pyogenes will have a zone of inhibition. S. agalactiae: They are gram positive and the colonies are flat, translucent, grey, white. They are soft beta hemolytic with a narrow zone of hemolysin. They are Lancefield classification B. A gram stain, and catalase test can be used. Another test is the CAMP test which will streak Staphylococcus aureus and Streptococcus pyogenes horizontal to it. Finally, a streak of Streptococcus agalactiae is done and if an arrow is formed it is CAMP positive. Any swab taken from vaginal/rectal areas is put into the Todd-Hewitt broth which allows only gram-positive bacteria to grow and then can be cultured. S. pneumoniae: Gram positive diplococcus lancet formation. They have a distinct capsule. They are alpha hemolytic. The colonies are dome shaped with young cultures that become caved in when older. A gram stain will help to differentiate between Strep viridians and S. pneumoniae. Another test that is performed is the susceptibility to optochin, S. pneumoniae is suspectable to this antibiotic. Enterococcus: Non motile, non-spore forming. 0.5-1.5 micrometer in size. They form small to medium white/grey colonies and variable hemolysis. Generally, we see that most of them are gamma hemolytic. A gram stain will show they are positive. A bile esculin test can be performed which will prevent the growth of other Streptococcus but Enterococcus will hydrolyze esculin and cause a black precipitate to form. We can also put this type of bacteria in a high salt test tube like 6.5% NaCl. They are able to form in this where other group D Streptococcus are not. c. Disease states (we discussed) S. pyogenes: Pharyngitis, strep throat, can cause fever, chills, swollen tonsil, and glands. This is treated with antibiotics. Cutaneous infections like impetigo can occur. Scarlet fever is another disease that can occur. S. agalactiae: This can cause invasive disease in newborns like pneumonia and meningitis. It can be carried in women and therefore women who are pregnant will be tested for this approximately at 35 weeks of gestation. If positive an antibiotic is given. S. pneumoniae: Pneumonia and otitis media are two infections that are caused by this. This is the number one bacteria that can cause pneumonia. Otis media can also progress to meningitis and bacteriemia. Enterococcus: These cause nosocomial infection on indwelling devices like urinary catheters and prosthetic heat valves. d. Key virulence factors associated with those disease states. S. pyogenes: Virulence factors for strep throat are lipoteichoic acid, fibronectin protein, and M protein. These all allow for adhesion to the pharyngeal cells. For cutaneous diseases we see SPE B are involved and cystine proteases which will help promote invasion. Scarlet fevers virulence factors are SPE A which causes a large nonspecific immune response by inappropriately activating T cells. This type of infections can disseminate. S. agalactiae: A capsule is a key virulence factor and is composed of sialic acid. S. pneumoniae: The virulence factors for pneumonia are the capsule because without it this is not virulent. Unconfirmed virulence factors include hemolysin, IgA protease and hyaluronidase. Enterococcus: The virulence factors for this species includes adhesion factors, serene protease, and gelatinase. They allow for a biofilm to form on catheters. e. If there is a vaccine and what it is S. pyogenes: None S. agalactiae: None S. pneumoniae: There is a vaccine also referred to as pneumococcal. There is one for adults and kids. The adult vaccine is PS23 and has 23 serotypes while the child vaccine is PV7 with 7 serotypes. Enterococcus: There is not a vaccine so to control it aseptic technique is important.