1. Compare/contrast between a gram positive cell wall and gram negative cell wall. Choose either the gram positive cell type OR gram negative cell type and describe the step-by-step process (and results) of Gram Staining for that microbe.
2.Fungi are eukaryotic microbes that are highly ubiquitous in the environment and although most strains do not cause disease in humans, there are approximately 300 types of mycoses (fungal infections) that are of relevance to clinicians. For this discussion board, perform research to determine a mycosis of clinical interest and provide the information for your selected disease below (see 1-6).
Scientific Name of the Fungus (should be italicized)
Name of the mycotic infection
- How the disease is transmitted (or source of the infection)
Patient symptoms & site of infection
- Is this a opportunistic infection, a nosocomial infection or a community acquired infection? (explain your logic)
- References (excluding .com, .net, etc)
- 3.Compare/contrast endotoxins and exotoxins. Choose a microbe and one exotoxin produced by it to describe the affects it has on the human host.
Post 1
1. In order to differentiate between different bacteria, a gram staining process needs to be completed. The gram staining process begins with gathering some materials, primary stain crystal violet, secondary stain safranin, a mordant iodine, and decolorizer 75% ethyl alcohol. To begin the gram staining process, clean the microscope slide with the 75% ethyl alcohol. The microscope slide needs a drop of sterile water on it now. Sterilize the inoculation loop using a flame to heat it up. When the loop is red hot, it will be hot enough. Using the inoculation loop gather some of the bacteria and place on the slide. Once the sample is smeared on the microscope slide, allow the slide to air dry and then heat fix the sample to the slide by passing through the flame. Add the primary stain crystal violet, this stain will stain each gram negative and gram-positive bacteria. Leave the crystal violet stain on the slide for 30 seconds. The next step is to rinse the slide in the sterile water, the goal is to remove most of the stain from the slide. The mordant is next, apply the iodine to the slide and let it sit on the slide for one minute. Rinse the slide in sterile water again with the goal to remove the dye from the slide. The 75% ethyl alcohol is needed now, run it on the slide to remove the remaining primary stain from the slide. Do this until the run off from the slide runs clear. Rinse the slide with sterile water to cleanse the slide again from any remaining dye. Safranin is next, placing on the slide and remain on slide for one minute. The safranin is a counterstain and will assist with identifying gram-negative vs gram positive bacteria on the slide. After the safranin is on the slide for one minute, rinse in sterile water. The slide is ready to be viewed under the microscope now.Taking a deeper look at the gram-negative bacteria. Gram-negative will appear pink under the microscope, as the cell wall has a limited layer of peptidoglycan. The peptidoglycan layer is what retains the primary stain crystal violet. In gram-negative bacteria there is only a single layer of peptidoglycan layer which is sandwiched between diderms layers. The gram-negative cells are more resistant to antibodies because of the impenetrable cell wall and develop resistance more quickly.
Post 2
Gram staining is an invaluable technique for identifying characteristics of bacteria based upon how they react to reagents applied during the process, which is determined by the structure of the organism’s cell wall. It is a practical first line tool for diagnosis of infection type and can lead medical professionals in the right direction when choosing which type of drug or treatment to use (Talaro, 2017). Gram positive bacteria have smooth walls that range in thickness from 20-80 nanometers, lack an outer membrane, and are generally susceptible to antibiotics. Gram-negative bacteria on the other hand have a wavy, double layered thin cell wall that is typically only 8-10 nanometers and are often resistant to antibiotics (BYJU, 2021).The process for staining a gram negative cell type is relatively simple. The reagents used in the technique are a primary dye (crystal violet), a mordant (Gram’s iodine), alcohol, and a red dye (safranin). First, crystal violet is applied to the specimen to dye all of the cells a purple color. Secondly Gram’s iodine is applied and causes the crystal violet dye to form clumps that become trapped in the cell wall. Since gram-negative bacteria have a very thin cell wall there is little room for the crystals to form in and they do not have enough of a presence to stand up to the third step. That step involves using an alcohol rinse to dissolve the lipids and peptidoglycans in the outer membrane rendering the specimen colorless. In the fourth step the red dye is applied and gives the now colorless specimen a red or pinkish tint.The final step is to examine the specimen under a microscope to see the results. In gram-negative bacteria, one sees a pink or red tint to the cells. Now that the cells are dyed the shape is easier to determine and can lead to diagnosis based on the two shapes of gram-negative bacteria: rods or cocci. Based on the color and shape, medical professionals are able to make diagnoses quickly and efficiently.
Post 3
3..Endotoxins are bacterial intracellular toxins composed of a phospholipid polysaccharide complex that serves as an essential aspect of the gram-negative bacterial cell wall. The proteins demonstrate high specificity for a target cell as they can initiate extremely powerful effects, such as severe shock and fever. Endotoxins also affect cells by damaging their membrane, beginning lyses, or by disrupting intracellular function. It also has a variety of systemic effects on tissues and organs. Depending on the amounts, endotoxins can cause fever, inflammation, hemorrhage, and diarrhea. Blood infection can cause fatal endotoxic shock caused by large amounts of endotoxins released into the bloodstream. Unlike the many different forms of exotoxins, there is just a single type of endotoxin. Exotoxins are different in that the molecule is secreted by a living bacterial cell into the infected tissue. It is a polypeptide, which is an integral aspect of the outer membrane of cell envelopes. When performing a direct comparison, exotoxins can become toxic in small amounts, they are unstable, they stimulate antitoxins, do not usually stimulate a fever, and are secreted from a live cell. On the contrary, endotoxins are toxic at higher quantities, stable, do not stimulate antitoxins, contribute to fever stimulation, and are released from a cell wall during lysis. While different, both components are produced by bacteria facilitate the process of infection in a host cell (Talaro, 2017). One microbe and exotoxin of interest includes Corynebacterium diphtheriae that produces diphtheria exotoxin. The production of this toxin results in the inhibition of protein synthesis and cell death. While the molecular mechanism of the exotoxin is unclear, adhesion of the molecule is mediated mainly by pili that are attached to the bacterial cell wall, and they contribute to colonization in the host. Diphtheria is usually an acute respiratory infection that can be classified into respiratory, cutaneous, and ocular disorders of the body. The presence of a thick, grey layer on the throat is indicative of an acute infection of diphtheria. Neuropathy and myocarditis are systemic effects that could result from this condition as well. Clinical diagnosis of this condition is confirmed with a bacterial culture along with enzyme and toxin detection tests. Fortunately, this can be treated with the administration of diphtheria antitoxin and antimicrobial therapy. Due to enhanced vaccine coverage, this condition isn’t as prevalent today even though it demonstrates a high fatality rate of 5-17% for those who are unvaccinated. Diphtheria mainly affects children younger than 15 years old and was a major cause of childhood morbidity and mortality before the vaccine era (Sharma 2019).
Post 4
Endotoxins produce weak immunogenic lipopolysaccharide complex molecules which are moderately toxic to other organisms. Some examples are known as Cholerae toxin which is produced by Vibrio cholerae. Endotoxins cause what they call Meningococcal septicemia disease. This is an infection in the bloodstream caused by bacterium. Exotoxins are heat labile polypeptide molecules excreted by bacterial cells with high antigenic properties which are highly toxic to other organisms. Some examples include both alpha toxins and delta toxins that are produced by staphylococcus aureus. Exotoxins cause botulism, also known as food poisoning that has been caused by a buildup of bacteria within the human body. Microbe: Alpha toxins. Alpha toxins are different protein toxins that are produced by bacteria. Exotoxin produced by alpha toxins can be known as Staphylococcus aureus. Staphylococcus aureus is a dangerous disease caused by a gram positive bacteria.There are many forms of staphylococcus that can be harmful to the human host. However this form of staphylococcus can typically be found in the upper respiratory tract and on the skin. It is often a bacteria that is clumped together which causes staph infections. Staphylococcus aureus is very contagious and can easily spread from person to person if it is unprotected. It can be seen to be very dangerous if it is left untreated due to how fast it can spread. It can cause symptoms such as stomach aches, vomiting, and even nausea. However the most serious cause of this disease can cause more serious symptoms like fever, and joint and muscle pain. The treatment process of this specific disease consists of drainage of the infection through antibiotics. Luckily most of the staph infections can be treated with antibiotics. However, one strand of staphylococcus that can not be treated by antibiotics is MRSA.
Post 5
The type of mycoses I have decided to research is that of Candida. The infection itself is called candidiasis, with this discussion specifically examining the fungus when in the vagina (CDC, 2021). According to Mayo Clinic (2021), candida albicans is the main fungus that causes infection, with there existing other types that should be treated differently. What is commonly known as a “vaginal yeast infection” can also be understood as any of the following: “vaginal candidiasis,” “vulvovaginal candidiasis,” or “candida vaginitis” (CDC, 2021). First, one should understand that a vagina is already comprised of candida. However, there is a balance of healthy bacteria, yeast, and candida. It is when this balance of components is thrown off and yeast is overgrown that an infection occurs. Certain conditions contribute to the disturbance of yeast growth, which will be examined next. People taking antibiotics could develop a yeast infection as these can kill healthy bacteria in the vagina. Further, if one does not have properly controlled diabetes or if they have a diminished immune system, their risk is greater. Increased estrogen levels—due to pregnancy, birth control pills, or hormone therapy—are also risk factors in women. The candida fungus might also be spread through sexual intercourse, although it is not a sexually transmitted disease, there is a risk of introducing fungus during sexual activity (Mayo Clinic, 2021). In mild cases, common symptoms include the following: vaginal itching or soreness, burning sensation during intercourse or during urination, abnormal vaginal discharge—including watery, or thick, white, odor-free discharge similar in appearance with cottage cheese (Mayo Clinic, 2021). In more serious infections there may be swelling, redness, or cracks within the vaginal wall (CDC, 2021). A yeast infection, or vaginal candidiasis would be an opportunistic infection, as this infection is caused by a common inhabitant of the body—candida that exists in balance in the vagina—that ceases to function optimally (Talaro, 2017). This can be contributed to a weakening of the host’s defenses by an outside source, an example being antibiotics attacking one’s own healthy bacteria.
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