micro case study questions 1-3
Why is a lumbar puncture needed to accurately identify the causative pathogen?
A lumbar puncture is needed to accurately identify the causative pathogen because the cerebrospinal fluid that is drawn from the puncture site circulates around the spine and brain. Since meningitis is an inflammation of the protective membranes covering the brain and spinal cord, it picks up the pathogen that is causing the inflammation, then, with tests or certain agars, the pathogen is able to be seen and identified.
If the acidic pH of the stomach can damage the mucosa, why doesn't it kill the pathogen?
H. pylori can survive in the acidic environment of the stomach by secreting an enzyme called urease, which converts urea into ammonia. Ammonia neutralizes the acidity of the stomach, which makes it more hospitalized for the organism.
How do amphotericin B and fluconazole kill fungal cells?
Amphotericin B acts by binding to the ergosterol of the fungal cell membrane causing changes in permeability and loss of intracellular content, while fluconazole inhibits the ergosterol synthesis.
Explain how the media color change indicates the presence of this pathogen?
By hydrolyzing urea, the urease enzyme releases CO2 and NH3. This increases the the pH of the test medium, which changes the pH indicators colour from yellow to pinkish or red. This indicates that the biopsy specimens are positive to H. pylori
What is the significance of temperature elevation and declining BP?
Doctors usually suspect sepsis when a person who has an infection suddenly develops a very high or low temperature, a rapid heart rate or breathing rate, or low blood pressure. To confirm the diagnosis, doctors look for bacteria in the bloodstream. Hot temperatures cause increased blood flow to the skin and dehydration, which can lower blood pressure significantly and lead to dizziness, fainting and falls, all of which are more dangerous in older adults.
What specific component of the E. coli was responsible for blackening digits, rapid BP decline, and worsening respiration? Explain how this occurs.
E. Coli is a gram-negative bacterium that releases Lipid A. Lipid A damages the endothelium by promoting the expression of tissue factor and proinflammatory cytokines, leading to apoptosis of these cells. In a blood stream infection, the presence of Lipid A can lead endotoxin shock and can cause the lungs to fill with fluid.
Explain how ECMO can improve oxygenation under these circumstances?
ECMO can improve oxygenation under these conditions because it pumps and oxygenates the patient's blood outside of the body, allowing the heart and lungs to rest and lessening the risk of infection. When a patient it connected to an ECMO, blood flows through tubing to an artificial lung in the machine that adds oxygen and takes out carbon dioxide. The blood is then warmed up to body temperature and pumped back into the patient's body.
What is the significance of elevated temperature in a postoperative patient?
Fever is usually attenuated by general anesthesia. Typically, patients develop a fever of greater magnitude in the postoperative phase. Postoperative fever is fairly common. The incidence of fever varies with type and duration of surgery, patient's age, surgical site and preoperative inflammation. Most early postoperative fever is caused by the inflammatory stimulus of tissue damage and exposure to foreign materials (ie, physiologic fever) that occurs during surgery and resolves spontaneously over a few days. The fact that this patient still has a fever while taking acetaminophen every 4 hours is surprising. Tylenol, also known as acetaminophen, is in the drug classes of antipyretic and analgesic meaning it is a fever and pain reducer. If the patient was not taking this every 4 hours then their fever could have been even worse and caused serious damage.
How does infection with this microbe result in mucosal erosion?
H. pylori protease and lipase degrade gastric mucus and disrupt the phospholipid-rich layer at the apical epithelial cell surface, allowing for cell injury from back diffusion of gastric acid. This cell injury may lead to cell death, believed to result from induction of apoptosis. H pylori enters the mucus layer of the stomach and attaches to the stomach lining.Generally, H. pylori adheres to gastric mucosa epithelial cells via the outer membrane protein and injects CagA into host cells via a type IV secretory system, resulting in changes in cytokine signaling and cell cycle control. H pylori causes the stomach to produce more stomach acid. This damages the stomach lining, leading to ulcers in some people. Chemically H. pylori infection increases gastrin release and diminishes mucosal somatostatin, but the net effect on acid secretion depends on whether the patient has corpus gastritis, because this inhibits ECl and parietal cell function.
Characterize this microbe?
Helicobacter pylori is a helical, gram-negative, motile, microaerophilic bacterium. H. pylori does not possess RNA chaperones like Hfq and ProQ, which are important factors in post-transcriptional regulation in many bacteria, including the model organism Escherichia coli. This characteristic has been an impediment for rapid regulatory RNAs identification in H. pylori but it also hints to original mechanisms for post-transcriptional regulation. This microbe lives in oxygen levels between 5%-12%. H. pylori measures 2 to 4 μm in length and 0.5 to 1 μm in width. Although usually spiral-shaped, the bacterium can appear as a rod, while coccoid shapes appear after prolonged in vitro culture or antibiotic treatment. The reason this bacterium has a spiral shape is because it's crucial for proper colonization of the stomach and cork-screwing penetration of dense mucin covering the stomach.
What is the most likely cause for this condition?
High procalcitonin levels are likely to indicate sepsis. The most likely cause of the sepsis is from a bacterial infection within the abdominal cavity. The perforation of the bowel in addition to intestinal adhesions causing a bowel obstruction are from the infiltration of a bacteria within the gastrointestinal tract.
Three appropriate antibiotics are being administered to treat the patient's infection. In this case, what can happen if the pathogens are killed too rapidly?
If an antibiotic such as vancomycin, rocephin, or metronidazole is administered too rapidly it can cause something called "red man syndrome." During or soon after rapid infusion of antibiotics patients may develop anaphylactoid reactions, including hypotension, wheezing, dyspnea, urticaria, or pruritus. Rapid infusion may also cause flushing of the upper body ("red neck") or pain and muscle spasm of the chest and back.
What is the connection between dark stools and bright red blood in the patient's Vomitus?
If the stomach and intestines are inflamed it can cause both of these symptoms. Inflammation of the stomach can cause acid reflux and thus can cause blood in the vomit. Inflammation in the intestines can cause bleeding in the stool.
Why is intubation proving insufficient to adequately oxygenate the patient's blood?
Intubation may be proving insufficient to adequately oxygenate the patient's blood because the patient was found to have E. Coli in their blood stream, which allows infection. When intubating the patient, the endotracheal tube enhances bacterial entry to the lung by serving as a reservoir for bacteria to remain isolated. Also, patients who are ill enough to require intubation already have disease-associated impairments in systemic host defense, which can add to the impairments caused by the use of an artificial airway.
What are the symptoms associated with meningitis?
Meningitis is an inflammation of the protective membranes covering the brain and spinal cord. There are multiple types of meningitis caused by different pathogens, like bacterial meningitis, viral meningitis, fungal meningitis (which is featured in the case), parasitic meningitis, amebic meningitis and non-infectious meningitis. Injuries, cancer, certain drugs and other types of infections can cause meningitis. The specific cause or type of meningitis present is important to know because the treatment differs based on the cause or type. Possible symptoms in anyone older than the age of 2 years include: Sudden high fever, stiff neck, severe headache, nausea or vomiting, confusion or trouble concentrating, seizures, sleepiness or trouble waking, sensitivity to light, no appetite or thirst, skin rash in some cases, such as in meningococcal meningitis. Newborns and infants may show these different signs: High fever, constant crying, being very sleepy or irritable, trouble waking from sleep, being inactive or sluggish, not waking to eat, poor feeding, vomiting, a bulge in the soft spot on top of the baby's head, and stiffness in the body and neck.
Why is the patient experiencing breathing difficulty?
Most cases of shortness of breath are due to heart or lung conditions. Your heart and lungs are involved in transporting oxygen to your tissues and removing carbon dioxide, and problems with either of these processes affect your breathing. If your blood pressure gets severely low, there's a significant danger that your body will not receive enough oxygen to carry out its normal functions. Decreased oxygen can result in impaired functioning of the heart and brain and cause difficulty with breathing
What is meant by a negative stain?
Negative staining is one of the many staining techniques that can be employed for viewing bacterial cell morphology and size. The advantages of the negative stain include the use of only one stain and the absence of heat fixation of the sample. A negative stain is the method of staining the background of a slide or culture with a liquid medium like Nigrosin and India ink that stains the background, leaving the microorganisms unstained. Due to repulsion between the negative charges of the stain and the bacterial surface, the dye will not penetrate the cell. In negative staining, the results yield a clear cell with a dark background. This method allows for better and clearer views of the microorganisms under electron and light microscopes.
If the infecting pathogen can raise stomach pH, why was the patient treated with 20 mg omeprazole?
Omeprazole is a protein pump inhibitor. Protein pump inhibitors have a strong inhibitory effect on gastric acid secretion, resulting in the concentration of antibiodics in the stomach. The inhibitory effects help to elevate the anti- H. pylori activity in the stomach.
How does the prescribed treatment of the peptic ulcers align with the results of the CLO test?
Omeprazole works to treat indigestion, heartburn, and acid reflux which would work well against the ulcer which is a sore within the esophagus, stomach, or small intestine. This can cause damage to the stomach lining and the omeprazole would reduce the amount of acid made in the stomach which would limit further damage to the lining of the stomach. Amoxicillin works to treat bacterial infections, so it would work against the growth of H.pylori and help the ulcer heal in a faster manner. Last, clarithromycin works to block acid production in the stomach. By decreasing the excess stomach acid, it would allow ulcers to heal.
Review this case carefully and recommend a course of action that might have improved the outcome.
One course of action that may have improved the outcome would have been for the physician to take action when the patient was reported to be flushed and diaphoretic at 13:30. Diaphoresis refers to excessive sweating that can be associated with medical conditions. Diaphoresis after surgery can often indicate the body is trying to fight off an infection.
Suggest a possible explanation for the patient's slightly elevated BP.
One reason the patient's blood pressure would be slightly elevated would be because of the infection. Infections can cause BP to raise due to the inflammation and the immune system that is trying to fight off the infection. Another reason the BP could be slightly elevated would be because some antacids and other stomach acids are high in sodium, which means they can retain a lot of water, which can raise BP.
What is significant about a 3.8 ng/ml procalcitonin value? How does this relate to the previous 2 questions?
Procalcitonin (PCT) is a prohormone of calcitonin that is produced by C cells of the thyroid gland and certain endocrine cells of the lung. In healthy persons, the blood level of PCT is undetectable or less than 0.5 ng/mL. High levels indicate a high probability of sepsis and also suggest a higher risk of progression to severe sepsis and septic shock. High levels may also be seen in people with serious bacterial infections, such as meningitis. To exclude sepsis and systemic inflammation, a concentration of ≤0.2 ng/mL is a useful reference range. As a cut-off for the diagnosis of sepsis, plasma levels of ≥0.5 ng/mL are interpreted as abnormal and suggest sepsis. This relates to the past two questions in the fact that all of these signs and explanations are pointing towards sepsis. These high levels also occur with inflammation which we know to be a current issue in the patient.
What media is used for the CLO test?
The CLO testing is performed during an endoscopy. The scope used for the endoscopy will search your stomach for any type of visible damage, and if any is found, the CLO test biopsy test will be conducted. A sample is taken and then put in a medium that contains urea. H. pylori can grow on different solid media containing blood or blood products (blood or lysed blood agar plates). Most studies have used Brucella agar or Columbia agar as the agar base. An amount of 7 to 10% blood improves the growth of H. pylori as compared with 5% blood. Horse blood may also improve the growth of H. pylori as compared to sheep blood. Supplement of agar with cyclodextrin B can be used for blood-free culture media for H. pylori, but with large differences between different batches of cyclodextrin. Egg yolk emulsion agar has also been described as a blood-free medium for growth of H. pylori. In a small study, egg yolk emulsion as a liquid medium was compared with four other liquid media described in the literature and it was found superior with regard to growth rate of H. pylori, but it contained too many non-H. pylori proteins to be useful for antigen production.
The physician is administering 3 antibiotics before knowing the identification of the suspected pathogen. What are the benefits of this strategy? What are the drawbacks?
The benefits of starting with antibiotics before knowing the identification of the suspected pathogen is that there will be an increased chance of success since the administration of numerous antibiotics has a greater chance of killing off the pathogen. In addition to the possibility of the antibiotics covering more pathogens another benefit would be that it would reduce the risk of resistance. The cons would be that it would be expensive to pay for antibiotics to be administered when you do not know for sure if they are going to work. They also can damage the normal microbiota and have possible side effects.
Identify the mechanism of action of each of the IV antibiotics used?
The mechanism of action for Vancomycin inhibiting the polymerization of peptidoglycans in the bacterial cell wall. Vancomycin binds to D-ala which prevents the synthesis and polymerization of NAG and NAM. This then weakens the cell wall which can cause leaks which will ultimately then lead to bacterial cell death. However, this antibiotic is only active against gram-positive bacteria. Rocephin mechanism of action works by inhibiting the mucopeptide synthesis within the bacterial cell wall. The beta-lactam portion of the Rocephin binds to peptidases in the membrane. The enzymes mentioned previously contribute to cell-wall synthesis and cell division. The binding of Rocephin to the peptidases causes the enzyme to lose its purpose and therefore the bacterial cell cannot produce effective cell walls which will cause cell death.
What is the reason why this pathogen appears so large? Hint: How does a negative stain work?
The pathogen appears so large because the negative staining procedure allows for a more accurate size and shape of the pathogen. In a negative stain procedure, the glass background is stained rather than the pathogen itself, highlighting the pathogen bright against a dark background.
Identify the pathogen responsible for these peptic ulcers?
The pathogen primarily responsible for causing peptic ulcers is Helicobacter Pylori also seen as H. Pylori. This most commonly occurs within children and is a very common occurrence in most individuals. Another contribution to ulcers is the ingestion of NSAIDs (non-sterile anti inflammatory drugs). H. pylori infection occurs when H. pylori bacteria infect your stomach. H. pylori bacteria are usually passed from person to person through direct contact with saliva, vomit or stool. H. pylori can also be spread through contaminated food or water. The exact way H. pylori bacteria causes gastritis or peptic ulcers in some people is still unknown.
Why was the patient susceptible to this opportunistic fungal infection?
The patient was susceptible to this opportunistic fungal infection because they had a weakened immune system due to their older age. People come into contact with fungus on a regular basis without getting sick, but people with weakened immune systems are more likely to get an infection from the fungal bodies.
What are the brown smears on the patient's back (in the previous slide)? Why was this product used before her invasive procedure? Does this photo explain why her back felt cold prior to the stinging sensation?
The reddish-brown swirls on her back are tincture (a concentrated extract) of Iodine which is an antiseptic (a substance that prevents the growth of disease-causing microorganisms). The iodine is used to disinfect the area by killing any bacteria or pathogens on the skin before inserting a needle that contains a local anesthetic. The anesthetic is used to numb the area before they collect the cerebral spinal fluid from the patient. The drying of the iodine causes the cooling sensation the patient feels. The sting is the puncture going in.
What symptoms are an immediate concern? Which are most important?
The symptoms that are cause for immediate concern would be the consistent headache for 9 days. This is very important because the patient describes it as "intolerable" and rating the pain 10/10. The other portion that could be the most important would be the difficulty answering questions. Anything revolving neurological problems are cause for concern. The fact that her neck is still probably is the most important complaint as that is a chief symptom of meningitis.
What condition is suggested by these symptoms?
These are both signs of Gastroenteritis. Gastroenteritis is an infection in the stomach or intestines caused by a virus or bacteria, such as norovirus or food poisoning. It can lead to bloody diarrhea. Nausea and vomiting may also be present thus correlating the blood stool and vomit
The figure follows this patient's procalcitonin levels over a 24 hour period. What do these data confirm?
This data confirms that with time the patients' procalcitonin levels keep rising. High procalcitonin levels may indicate sepsis or sepsis shock. Sepsis is a potentially deadly condition that can cause the body to overreact to a bacterial infection by releasing chemicals that cause damaging inflammation.
Endoscopy confirmed peptic ulcers. How did this procedure also identify the cause of the ulcers?
This procedure can help identify the cause of ulcers by seeing the lining of the stomach. The lining of the stomach will be irritated and inflamed as well as the presence of white splotches that can be identified as the H.pylori bacteria which is the cause behind having ulcers.
Identify three possible modes of transmission for this pathogen. As a nurse, what practices would you advise to break these chains of transmission?
Three possible ways that Heliobacteri pylori bacteria can be transmitted is through direct contact, food-borne transmission, and water-borne transmission. As a nurse I would recommend to avoid kissing, sexual intercourse, or contact with body lesions or body fluids of another individual. I would also recommend that the patient avoids sharing food or drink with others to break the chains of transmission.
Approximately 9 hours after blood cultures were drawn, growth of E. coli is identified. Are these results expected in this time frame? Explain.
Time to positivity is in part related to the number of organisms initially inoculated into the bottle. For example, assuming a doubling time of 20 minutes for Escherichia coli and a threshold of ~5 x 108 colony forming units/mL for a positive blood culture, one organism would be detected in about 10 hours and 100 cells in about 7.5 hours. Although the difference in time to positivity cannot quantitatively indicate the number of cells initially in the blood, a longer time to positivity suggests lower initial organism burden. So yes, these results are expected in this time frame.
What is suggested by turbidity in the CSF sample?
Turbidity means the quality of being cloudy, opaque, or thick with suspended matter. Normal CSF should be clear but if CSF is cloudy The first reason is the presence of large numbers of WBC's. In CSF infection, the CSF can appear turbid as the number of WBC's increases. They accumulate to the point of making the CSF appear cloudy or it can even appear as pus. The second reason for CSF discoloration is due to red cells and their breakdown products.
Why have high doses of epinephrine, norepinephrine and vasopressors been administered?
Vasopressors have been administered because the patient's blood pressure was 48/28, which is dangerously low. Vasopressors help you raise your blood pressure when it's so low that you can't get enough blood to your organs. This is the case with shock victims and people with other conditions that make their blood pressure very low. Providers often give vasopressor drugs to you through an IV
