Microbiology Final Case Studies Questions and Answers

Microbiology Final Case Studies Questions and Answers A 22-year old woman with slight fever (38.5C), a complaint of frequent urination, burning on urination, vaginal discharge and a small lesion on the labia. The woman had three sexual partners in the past six months. Her last sexual contacts were about 7 days earlier. Developed mild symptoms about 5 days earlier, beginning with a discharge from the vagina. Pain on urination about 3 days earlier. Urine analysis revealed a pH of 8.2, some white cells and a few red blood cells. A smear of the vaginal secretion showed a number of Gram-negative cocci. 1) What is your diagnosis here? Gonorrhea or vaginitis. 2) What clinical features are critical to your diagnosis? Gram-negative cocci, time in which the symptoms appeared, high pH of urine, and vaginal secretions or discharge 3) What medication would you precribe, if any? Tequin or sethtrokin 4) What further actions must be taken? Practice safe sex Prescribe Doxycylin if Chlamydia is also contracted Sexual partners should be tested and treated Do not participate in sexual activity until infection has subsided A 62-year old diabetic black man presents in the emergency room with a swollen left leg with areas of blanching and blue mottling. A "foul odor" is coming from a dressed wound. The physicians remove the dressing and a brownish fluid is seeping from a wounded area. The fluid contains what appear to be small bits of the tissue. No pus appears to be present. The wound has a strong "rotten" odor. Five days earlier, while at his work as a farmer, he caught the leg in his manure spreader, sustaining a deep, crushing, grossly dirty injury. His wife cleaned the wound as well as she could with soap and water, dressed it with clean gauze, and wrapped it tightly with an elastic bandage to stop the bleeding. The second day they redressed the wound and applied triple antibiotic ointment. The patient treated his pain with ibuprofen (Advil). He reported the pain was not very bad for the first 72 hours. In the past 24 hours, the leg 1) What is your diagnosis in this case? Gas gangrene (Clostridium) 2) How should this wound be treated? Remove dead and infected tissue, amputation is necessary; antibiotics for treatment- IV antibiotics 3) Is this a life-threatening condition? Yes very. It moves fast, and only gets worse 4) What is the significance of his diabetes, if any? Blood supply inadequate to wound/throughout the body; components needed to heal cannot be properly be delivered due to the diabetes A 58-year old lawyer presents in the emergency room with headache, irritability, generalized muscle pain and uncontrollable back spasms. He has back spasms that became extremely painful. He is on medication for high blood pressure (beta blocker) and has mild asthma. He injured himself about 10 days earlier, puncturing his left arm with a nail from an old barn he is tearing. The wound has produced moderate quantities of pus, but he has been keeping it clean. The wound was sampled for microscopic examination and culture, and the results indicate gram-positive anaerobic, bacilli. The back appears to have very tight contractions and spasms. 1) What is your diagnosis here? Teatnus 2) What is the scientific name of the organism? Clostridium tetani 3) What is the proper treatment of this problem? Tetanus immune globin (TIG), debridement, and Td vaccine Muscle relaxer for muscle spasms along with antibiotics 4) How could this have been prevented? Tetanus toxoid with booster every 10 years A 4-year old girl presents at the emergency room with bloody diarrhea, fever and vomiting. The child's mother reports that the child has had these symptoms for about 24 hours and she has not passed any urine for about 12 hours. The child is enrolled in a day care center and the group had recently made a field trip to a fast food place to learn about different jobs. The children had a lunch of ground beef, fries and cola after meeting with different workers. The child had a temperature of 39°C and showed physical signs of dehydration. Blood samples drawn showed evidence of greatly reduced kidney function and lysed red blood cells. 1) What is your diagnosis here? Hemolytic Uremic Syndrome also called Hamburger disease 2) What is organism is responsible? E. coli 0157:H7 3) What pathogenic feature of this organism caused the severity of this problem? Shiga toxin produced 4) What were the critical features to your diagnosis? Kidney Failure, high fever, lysed blood cells, and bloody diarrhea You have a possible infectious condition that you are embarrassed to discuss with the physician with whom you work. You have worn artificial nails for several months now and noticed that the one on your left ring finger falls off regularly. The real nail underneath has become white and chalky, and the skin around the nail is beginning to have little white lines in it and look a bit chalky, as well. 1) What disease do you suspect? Explain why. Fungal infection due to the white chalky lines 2) What would you suggest be done for a more definitive diagnosis? Potassium hydroxide smear; this will define that it is a fungus 3) Can you treat this yourself with an over-the-counter drug, or do you need to see a physician? See a physician to get an oral antifungal: can only be treated topical 4) What other conditions are caused by dermatophytes (Microsporum, Trichophyton, and Epidermophyton)? Ringworm and athlete's foot 5) What is special about them that make them capable of thriving in their anatomical niche on their hosts? The fungi use enzyme kertinase to get keratin; dark and moist environment In the late 1980s there was an epidemic among livestock in Great Britain. Approximately 180,000 cattle were found to have "mad cow disease," so named because the condition attacks the central nervous system, which leads to bizarre behavioral symptoms and often death. The disease seems to be caused by an "unconventional transmissible agent," meaning it is unlike most microorganisms. No genetic material from this organism has ever been detected in infected tissues, although foreign protein fibers accumulate in large concentrations in the brain. Infected cows were still turning up in the late 1990s. There was great alarm in the late 1990s when dozens of humans starting turning up with symptoms similar to those seen in the cows in the late 1980s. More than 50 people have been diagnosed with the human variant of mad cow disease. This is consistent with the approximately 10-year incubation period of this unconventional tra 1) What is the name for a transmissible agent that contains only protein and has no genetic material? Prion 2) What is the formal name for mad cow disease? Explain the name. Bovine means cow, Spongiform means protein accumulation on brain (sponge) Encephalopathy means brain disease 3) The human form of the disease is called something else. What is it? varient Creutzfeldt-Jakob disease (CJD) 4) Scientists suspect that the humans infected during this outbreak acquired the disease from eating meat from diseased animals. Even when meat is well cooked, it transmits the infection. What does this say about the infectious agent? Prions resistance to survive high heat 5) Livestock control measures have been in place in Britain for several years now. Can we expect more human cases with links to the British cattle epidemic, or is it behind us? Defend your answer. Yes, because the incubation period for these prions is long, as well as they are hard to kill You are at a baseball game when a man experiences dizziness and nearly faints in the stands next to you. He reports that he has had a headache off and on since he had a tooth extracted four days ago. This evening he is feeling very weak. His blood pressure is normal. When you listen to his heart you note that he has a pronounced murmur. He reports having had rheumatic fever 15 years ago. You examine his fingernails and find one that has tiny petechial hemorrhages under it. 1) Which cardiovascular infectious condition is this? Subacute endocarditis 2) What is the most likely causative organism and the route of transmission? Streptococcus viridans; gastrointestinal route 3) What's the connection, if any, with rheumatic fever? Damage to heart valves which can lead to bacteria attaching 4) Why did you look at his fingernails? Capillary hemorrhaging; oxygen in bloodstream Eyes are another place to look other than the fingernails 5) What type of culture would a physician most likely order, and why? BAP to look for hemolysis; alpha= hemolytic Julie's boyfriend Doug has not been feeling well for the past 10 days. He has congestion in his lungs and has been very tired. She talked him into going to the doctor a week ago when his temperature was 38.5°C. The doctor gave him some oral amoxicillin. But she still thinks he looks sick. Julie, Doug, and their 3-year-old daughter have just moved to Ohio from Arizona. Doug is a park ranger and he loves his job, but for the past three days he has felt too sick to go to work. His respiratory symptoms have not improved. 1) As the physician's assistant in the office, you are the first to examine Doug. 2) What's your tentative diagnosis, based on the history? Histoplasmosis (Ohio Valley Fever) 3) Which components of the history support your tentative diagnosis? Amoxicillin isn't working, plus he is outside a lot so he is around animal droppings (bird and bat droppings- he must go in caves) 4) Doug's condition has not responded to the antibiotic. List two possible reasons for this finding. It is a fungus and has resistance to the drug 5) Should Julie worry that Doug can transmit the infection to her or to their daughter? No; because it is breathed in by the fungal spores 6) What precautions can be taken by other workers who may be regularly or heavily exposed to bat or bird droppings? Minimize exposure, wear a mask and protective clothing and do not touch bird droppings A 63-year-old complains of a high fever. The fever is not constant, but intermittent. When you press him for details he estimates that every three days or so he suffers these debilitating "sweats." He usually has headaches and muscle aches during the episodes. They keep him home from work. After half a day or so he feels better. He reports that he has experienced these episodes for about two months. 1) What is the name of the condition you suspect? Malaria 2) What should be your first question about the patient's history? Where have you traveled? 3) What is the most likely causative organism (genus and species)? Genus: Anopheles Species: Plasmodium vivax 4) Is this pathogen eukaryotic or prokaryotic? Eukaryote because it belongs to the protozoans 5) What are the two main places in the human body that are exploited by the causative organism in this disease? Liver and Red Blood Cells You're at the beach in Florida with your friends over spring break. Everything is fine until Janet complains of an insect bite on her ankle. It looks like a big mosquito bite. You rummage around under the sink in the bathroom and find a very old bottle of aloe lotion. She rubs it on the bite and you both return to the patio. The next day Janet's ankle is very red in the area around the bite. It is hot and tender to the touch. Being pre-med students, you decide not to take a chance and you drive her to the local hospital's emergency department to have it looked at. You leave the hospital without seeing a doctor. You go back to the house and Janet puts more aloe lotion on the bite. That night Janet's roommate wakes you at 2 A.M. saying that Janet is crying and sweating. When you get to her room you see that Janet looks very ill. She is covered in sweat but is shivering. She is very pale, almost blue in places, and ther 1) What do you suppose is happening with Janet? Is it dangerous? Septicemia and yes it is dangerous 2) Explain Janet's symptoms described in the last paragraph of the case. Vasodilation and chills 3) What organism causes this condition? Streptococcus pyogenes; Staphylococcus aureus 4) When you relate the history of Janet's condition to one of the paramedics, you notice that she writes "secondary to cellulitis" on her pad of paper. What is cellulitis, and what does it mean that Janet's condition is "secondary" to it? Cellulitis is inflammation of the skin and Secondary cellulitis is septicemia 5) How should Janet's condition be treated at this point? Cultured in blood media and IV antibiotics Kate, your sister-in-law, is about to undergo fertility treatments. Her doctor insist that she receive the rubella vaccination, and then wait several weeks before beginning the actual fertility regimen. Kate calls you and wants to know why she has to do this. You ask her if she is able to produce evidence of vaccination for rubella (also known as German measles). She says no; her family had a house fire a few years ago and all those records were lost. "But I had German measles when I was in second grade!" she says. "I remember that I was really sick and missed almost a month of school." You suggest that she follow her doctor's advice and get the immunization. 1) Why would a fertility specialist recommend the rubella vaccine? Why does he suggest a waiting period after vaccination and before conceiving? Rubella can cause serious birth defects. Because it is a live vaccine. Spontaneous abortion 2) When do most children in the United States receive their rubella immunization? 12-15 months and 4-6 years. MMR vaccine 3) Kate suggests that she had rubella in second grade, but the disease she described doesn't sound like rubella to you. Why not? Disease is often mild it also passes after a few days. She was describing regular measles 4) Kate says the doctor gave her the option of having her blood checked for antibodies to the virus, to test her immune status. Would this test be checking for immunoglobulin M or G (IgM or IgG)? Explain your answer IgG because IgM would be for a new infection. IgG is for an old infection. Do two spearate tests for IgM and IgG. If it increases then it is IgM 5) If a physician was checking for a current rubella infection and only had available test for IgG, how could he or she be certain the infection was a new one? Timeline test, wait for 2 or 3 weeks In the winter of 1993, five students from one middle school in Seattle were diagnosed with meningococcal disease. The incidence of the disease had been climbing for two years in that area of Washington State, as well as in the rest of the country, and has continued to climb since then. In the Seattle outbreak, health officials identified one strain of the causative organism that was responsible for the increased incidence. 1) What type of organism would you look for in a Gram stain of blood or cerebrospinal fluid in these cases? Gram-negative streptococcus- niceria menigiditis 2) What is the organism's portal of entry to the host? Respiratory and Geniourinal tract 3) Could you swab the portal of entry (see question 2) to detect the presence of the organism? Why or why not? No 4) What types of symptoms are associated with meningococcal disease? Fever headache, stiff neck, back pain, and confusion 5) A total of 900 students attend the affected middle school. What measures should have been taken to protect the remaining 895 students from acquiring meningococcal disease? Send the infected students home and give antibiotics (penicillin) to the students who have been exposed. Has to be done in 24 hours On Christmas Eve, 2010, you were working as a clerk in an Atlanta emergency room. At 3 A.M., a man and two women arrived with screaming 6-year-old girl. The man tried to explain what was wrong, but he spoke only Spanish and you had a difficult time understanding him. The girl's mother was sobbing and you couldn't hear what she was saying. The other women spoke a bit of English and explained to you and the nurse on duty that this was her sister's family, who had just arrived from El Salvador. The aunt did not know what was wrong with her niece but told you that the father was repeating the words for "break bone." The nurse examined the girl and found that she had a rash and a fever of 40°C. Although the girl seemed to be in severe pain, the nurse found no bone fractures. The father, shaking his head violently, said something urgently to his sister-in-law. She interpreted his frantic statement for you, "He said it's in 1) What is your diagnosis? Dengue (Dengi) Hemorrhagic fever caused by a virus 2) What connection does this disease have to broken bones? Contortions due to intense joint and muscle pain Commonly called break bone fever 3) This is a vector-borne disease. What is the name of the most common vector? Aedes Aegypti (mosquito) 4) What other infection is transmitted by the same vector? Yellow Fever 5) The next night when you arrived at work the little girl seemed to be doing better. The rash had subsided and her fever had lowered. But on the third night you arrived to find that she had been transferred to intensive care after hemorrhaging internally. Is this still consistent with your original diagnosis? Explain. Dengue hemorrhagic fever is a more severe form of illness- may lead to shock 6) This all sounds very bad, but you're somewhat comforted by the fact that this disease is not found in the United States. Right? No, there has been an outbreak in Hawaii due to a secondary vector (A. albopictus) that has spread in the Southeastern U.S. You have just been accepted into the nursing school at a local medical center. The program requires that you have a physical, which includes tuberculosis (TB) test as well as the hepatitis B recombinant vaccine series. The nurse administering the TB skin test explains that if significant swelling occurs around the injection site, you will probably have to have a chest X-ray to determine if you are infected with Mycobacterium tuberculosis. One and a half days later you wake up and look at your arm, which appears swollen in an area about the size of a quarter around the skin test. It is red and tender to the touch. You're alarmed; could you have TB? 1) Why does the reaction take 36-48 hours to show up? Latent vs. active infection in previously infected; sensitized T cells react with proteins (Mantoux test) 2) If you have a tuberculosis infection, why doesn't the whole body, or at least the respiratory tract, react when the antigen is injected during this diagnostic test? Only penetrates first layer of skin (superficial injection) 3) You are referred for a chest X-ray, but the results are inconclusive. The clinic doctor prescribes a six-month course of isoniazid (abbreviated INH). You take the medicine according to the pharmacist's instructions. Six months later you are taking a medical microbiology course as part of your nursing curriculum. On the day you study tuberculosis you suddenly realize why you had a positive skin test. It has nothing to do with a true infection, but with the fact that you were born in the Netherlands. Your family moved to the United States when you were 4 years old. What do you suppose is going on here? Discuss as fully as you can. The patient got the TB vaccine in the Netherlands so the TB is positive You were vaccinated (insert vaccine) which is done in the Netherlands, you have sensitized T cells 4) You have a friend in your hometown that is HIV-positive. When you told her about your TB scare, she said that her specialist can't use the TB skin test, even though HIV-positive people are at higher risk than the healthy population for TB. Why is the skin test not recommended for HIV-positive people? HIV patients are more susceptible to TB. HIV can produce a false negative on TB test because of immune system. They already have a low T cell count. You are at dinner with four of your friends. A local outbreak of Escherichia coli O157:H7 has been in the news. The news stories suggest that the source of the infection was unpasteurized apple cider, but the group wants to know if hamburgers are safe. They remember that there was a big outbreak of E. coli associated with burgers from a fast-food restaurant in the Northwest. They turn to you, since you are a nurse. You tell them to order steaks. They ask if you're buying! 1) Why steaks instead of hamburgers? Beef is contaminated after processing. Steak comes from one part of the cow, where as beef can come from different parts of the cow which can include part of the intestine. 2) One of your friends acts disgusted and says she'll order a salad instead. Will this guarantee her safety? Why or why not? No, often times the package is infected. If the vegetables may have not been washed properly. 3) One of your friends says that her sister gives her baby apple juice every day. Should she stop? Explain your answer. No apple juice is not connected to unpasteurized apple cider 4) What are the symptoms of E. coli O157:H7? Kidney failure, diarrhea, fever 5) Another friend says that his family has always eaten rare hamburgers and no one has ever gotten sick. He thinks it's all a bunch of overblown media coverage and says he will continue to eat his favorite delicacy, raw hamburger meat on crackers. What should you tell him? Tell him to change his eating style to cooked meat because E. coli is most likely in undercooked/raw meat. Family may not have been exposed to that strain because it is a new strain. Your sister Pam called you last night; upset about her recent visit to the pediatrician (she has a 3-year-old son). Actually, she was upset about the discussion she had afterward with her husband, who was adamantly opposed to having her son vaccinated against hepatitis B virus (HBV). Pam called you because the doctor had convinced her that it was necessary, and indeed routine, to vaccinate young children. Her husband believes that hepatitis B is mostly acquired through sexual contact and drug use and that it's ridiculous to vaccinate a 3-year-old. Pam wants your advice before continuing this discussion with her husband. 1) First of all, is Pam's husband correct about transmission of the virus? Elaborate. He is partially correct about transmission, however transmission can be through blood contact or breastfeeding, even through infected saliva. 2) How severe is this infection for young children? Severe if the child is not vaccinated and the mother is infected 3) Pam says she'll also remind him that in the last year the news-papers have reported at least three hepatitis outbreaks traced back to restaurants. Respond to her statement. Pam is most likely talking about Hep. A 4) While you're on the phone with Pam, her husband comes home from work. He hears your conversation and says in a loud voice, "That vaccine is not safe! It's one of those genetically engineered things!" What can you tell Pam about how the vaccine is made and whether it is safe or not? The vaccine is genetically modified and produced in yeast, so there is no live vaccine therefore it is safe On Christmas Eve a few years ago, the Georgia State Health Department announced that two elderly people had died during the previous six weeks, apparently after ingesting tainted meat. Ten additional nonfatal cases were reported in the state during this period. The symptoms include fever and muscle aches and often diarrhea and nausea. Occasionally, the central nervous system was affected, resulting in confusion, stiff neck, headache, and convulsion. The nationwide outbreak affected approximately 40 people, with a particularly high infection rate in pregnant women and a significant number of deaths among fetuses. The Centers for Disease Control and Prevention (CDC) issued a list of people who were at particular risk for the disease. These include pregnant women, newborns, people with weakened immune systems, and the elderly . The CDC and the U.S. Department of Agriculture suspected prepackaged meats, such as hot dogs 1) What is the most likely causative microorganism in this outbreak? Listeria monocytogenes 2) Why is this infection associated with processed meats, but usually not with hamburger or cuts of meat including pork, beef, or chicken? Meat is contaminated after processing. High temperature will kill them, but refrigerator temperatures won't 3) Epidemiologists describe a microorganism's pathogenicity as the proportion of people who become ill after being exposed to the microorganism. (An infection that is subclinical in most people who acquire it is considered to have low pathogenicity.) After considering the types of people at high risk for the disease, would you suppose that this organism has high or low pathogenicity? Explain your answer. Listeria is relatively low pathogenicity because it has an effect on those with a weak immune system You are working as a receptionist at the only family practice in a small town in Idaho while you are studying to become a physician's assistant. On a Saturday morning you are the only officer worker there when a call comes in from a local church. The congregation is hosting a family that moved to the United States from Peru six weeks ago and is helping them find housing and work. The woman on the phone identifies herself as Leslie, a church member. She says that the mother of the young family became ill yesterday and seems extremely ill now. Her symptoms started out as stomach cramps and quickly progressed to a very watery diarrhea. Leslie tells you that the patient is pointing to her calves and crying. You ask Leslie how many stools the sick woman has had in the last 12 hours. She replies that it is almost constant and that the woman can no longer leave her bed at all. When asked, Leslie says there is no blood in th 1) When the doctor opens the door you whisper that you think there's a case of ________ on the phone? Vibrio cholera 2)The doctor's eyes widen and she asks you how you came to the conclusion. What is your reply? Profuse and watery diarrhea and leg cramps and white flecks (dead cells from the mucus) 3) Why was the doctor initially dubious about your diagnosis and why does the patient's recent immigrant status convince her that your diagnosis were correct? Because it isn't common in the U.S. it usually inhibits contaminated water (feces) 4) The doctor asks you to tell Leslie to call 911. The sick woman should be transported to an emergency room right away and the doctor will call ahead and meet her there. What is the first intervention likely to be performed when the patient arrives? Hydration Stool sample or rectum swab for lab test 5)The incubation period for this disease is one to four days. Can you think of any way that the young mother could have been infected so recently even though she has been in this country for six weeks? Consumption of water or food contaminated with cholera 6) The next day you ask the doctor about the patient's status. She says that currently the patient is receiving a course of the antibiotic ciprofloxacin, though it won't help her. Why won't it help her and why was it prescribed if it won't? Antibiotics shorten the coarse of the disease and diminish its severity