Digestive System Infections Case Studies and Homework

Which of the following clinical signs and symptoms is characteristic of a mumps infection? Select all that apply. (a) Swelling of the parotid salivary glands (b) Jaundice (c) Dry mouth (d) Quick onset of profuse and watery diarrhea

A -- Swelling of the parotid salivary glands C -- Dry mouth

You are tending to your preschool-aged patient who presents with excessive anal itching. The child's mother notes that the child woke several times during the night due to anal irritation. Gastrointestinal symptoms are absent. You recommend performing a tape test on the child. Which of the following diseases is the pediatric patient most likely afflicted with? (a) Ascariasis (b) Pinworm (c) Hookworm (d) Trichinellosis

B -- pinworm

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 office 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. In the meantime, the family is staying at a church-owned house and relying heavily on church members for help negotiating this new country and for translation while their English is still sketchy. The woman on the phone identifies herself as Leslie, a church member. She seems distraught. 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 water diarrhea. You hear moaning in the background and 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 the excreta. It is very clear with lots of little white flecks in it. You put her on hold and run down the hall to the examining room where a physician is doing a well-baby check. 1. When the doctor opens the door you whisper that you think there's a case of _____ on the phone. 2. The doctor's eyes widen and she asks you how you came to that conclusion. What is your reply? 3. Why was the doctor initially dubious about your diagnosis and why does the patient's recent immigrant status convince her that your diagnosis was correct? 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? 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? 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?

1. Cholera 2. Peru is known to have a cholera epidemic. Also the white-flecks in the stools. 3. In the U.S. there is not a cholera epidemic and traveling from an area such as Peru where there is an epidemic makes it more likely. 4. Given IV fluids to help rehydrate the patient since they will be extremely dehydrated. 5. Another member of the family could have had the disease or through infected food. 6. Antibiotics will not cure the infection, but it can help lessen the severity of the symptoms and shorten the course of the infection.

Environmental Health Specialists/Technicians work with environmental scientists and others to identify, assess, monitor, and correct environmental problems. Environmental Health Specialists may work for government agencies, laboratories, or consulting agencies. These specialists usually have at least an associate's degree. Classes that help prepare students for a career in environmental health include biology, biochemistry, public health, qualitative methods, and environmental science. It is common for employees to receive on-the-job training for health and safety laws and inspection practices. Common duties of Environmental Health Specialists include collecting and transporting environmental samples, running laboratory experiments, investigating complaints, implementing monitoring programs, and preparing and maintaining records. Although John never liked math and science in high-school, in college, a really great environmental science professor changed his mind. Before he knew it, he was taking courses in math, biology, chemistry, microbiology, and limnology (freshwater science). The limnology course really made use of all the biology, chemistry, and environmental science. He joined the environmental science club and started taking an interest in environmental issues. One day the environmental science professor (who also sponsored the club) told him about an internship with a local environmental consulting company. John applied for and was awarded the internship. He was hired by the company immediately after the internship was complete. Now, three years later, John still likes his job. He is assigned to the water quality group. The consulting company has contracts associated with two small lakes, two creeks, and one large river. He gets to hike into these areas for sample collection and checking monitoring equipment. This company is unique in that it has a small lab and runs many of the basic chemistry and biological laboratory tests onsite. John likes performing the lab tests. Periodically, he also has to investigate environmental contamination complaints and he always has to maintain careful records, not his favorite part of the job, but necessary.Today the weather outside is perfect; John is looking forward to hitting the trail to collect samples at Lake Timba. Lake Timba is nestled serenely in the woods and the water is crystal clear; there are not too many visitors--mostly just day hikers and fisherman. John is heading there today because there have been complaints about people getting diarrhea after drinking the lake water. Which of the following organisms can cause water-borne diarrheal disease? (a) Entamoeba histolytica (b) Vibrio cholerae (c) Leptospira interrogans (d) Cryptosporidium enteritis (e) Clostridium difficile

A -- Entamoeba histolytica B -- Vibrio cholerae D -- Cryptosporidium enteritis

After ingesting contaminated spinach, your patient presents with fever, jaundice, severe abdominal pains, and hemorrhagic diarrhea. You believe that the patient has contracted Enterohemorrhagic Escherichia coli. Which of the following laboratory techniques would be the most useful for identification of the foodborne pathogen? (a) Upper GI endoscopy (b) Microscopic analysis of the patient's fecal sample (c) Cultural analysis of stool sample on sorbitol-MacConkey (SMAC) agar (d) Colonoscopy

C -- Cultural analysis of stool sample on sorbitol-MacConkey (SMAC) agar

Waste water treatment laboratory technicians collect water and wastewater samples from various locations including plants, industrial facilities, and environmental water supplies. Chemistry techniques and basic instrumental analysis are used for physical and chemical properties such as temperature, conductivity, pH, suspended solids, dissolved oxygen, and turbidity. Microbiological analysis is used primarily for detection and identification of coliform bacteria. This profession requires excellent laboratory skills, as well as rigorous record keeping abilities to accurately complete and maintain reports as required by local, state, and federal regulations. 1. Richard loves his job working for the Tri-County Water District. In his seven years with the district, he has had many different jobs; currently he is a Waste Water Treatment Laboratory Technician. Today, he is doing his routine visit to one of the three Waste Water Treatment Facilities, where he'll collect samples of the treated water to take back to the lab. At the lab, his coworker Joey will do a chemical analysis of the water, while he does the microbiological analysis. To collect the samples at the waste water facility, Richard first dons his gloves, and then he uses the grab sample technique to fill his various containers, filling the sterile glass flasks he will use for his micro analysis last. To preserve the chemical integrity of the water sample and accurate microbial population estimates, these samples have to be chilled, and the analysis must begin within the hour. Once all of his samples are collected, he disinfects the outside of the containers, removes his gloves, and disposes of them in the biohazard bin. After washing his hands, he gets out a waterproof pen to label the containers with his name, the sample site location, and the date and time of the sample collection. Back at the lab, Richard gives the chemistry samples to Joey, and then heads to his microbiology lab. He starts setting up his tests to look for Enterobacteriaceae in the water samples.Which of the following best describes the Enterobacteriaceae group (enteric bacteria)? (a) pathogenic species only (b) Gram-positive bacillus (c) found only in the intestine of mammals (d) Gram-negative bacillus found in many locations including animal intestines (e) all motile, encapsulated non-pathogens 2. In water quality sampling, it is typical for the technician to look for fecal coliforms to indicate sewage contamination. Rapid carbohydrate fermentation is a reliable test for detecting the presences of fecal coliforms. Richard runs this test routinely: He pours 100 mlml of the sample water through a filtration membrane, and then he places the membrane on an eosin methylene blue (EMB) agar. He makes two duplicate plates and places the samples in the incubator at 44.5 degrees Celsius so that the bacteria can grow into colonies. These colonies will appear blue if rapid carbohydrate fermentation is occurring. Each blue colony on the filter is assumed to be the result of one fecal coliform in the original water sample. Richard is also planning to test for the presence of Salmonella in his samples, as local people had been reporting concerns about a large, new chicken ranch in the area. Richard needs to design a method to differentiate Salmonella from other similar species, so he gets out reference material that includes a dichotomous key, a tool to identity organisms through the process of eliminating characteristics that do not apply to it. Compare Salmonella to Escherichia. (a) Rapid lactose fermentation (b) No rapid lactose fermentation (c) No H2S formation (d) H2S formation 3. Richard decides to use Hektoen Enteric Agar (HE) to detect the presence of Salmonella and differentiate it from Escherichia. He carefully notes the composition of HE agar and the expected results.HE contains the following:- bile salts to inhibit most Gram positive bacteria- lactose, sucrose, salicin sugars available for fermentation- bromothol blue as pH indicator to detect acid produced by fermentation- sodium thiosulfate available for bacterial sulfur reduction- an iron compound that will react with any H2S produced and turn blackPossible HE results in the following:- Pink/orange/yellow colonies indicate sugar fermentation.- Blue/green colonies indicate no fermentation and no sulfur reduction.- Black colonies indicate sulfur reduction and no fermentation.He pours 100 mlml of the sample water through a filtration membrane, and then he places the membrane on HE agar. He makes two duplicate plates and places these in the incubator at 37 degrees Celsius. Richard cleans up and disinfects his work area. Next, he takes a quick inventory of the media, places an order for a few reagents, and heads home for the day. Which of the following are coliforms? (a) Shigella (b) Enterobacter (c) Klebsiella (d) Serratia

1. D -- Gram-negative bacillus found in many locations including animal intestines 2. Escherichia -- A -- rapid lactose fermentation, C -- no H2S production Salmonella -- B -- no rapid lacrose fermentation, D -- H2S production 3. B -- Enterobacter C -- Klebsiella D -- Serratia

A 35-year old accountant presented to his physician with a steady burning pain just right of the mid-line of the of the abdominal region in an area from 1 to 4 inches above the "belly button." The pain usually followed meals by about 1-3 hours. He had several episodes of vomiting, which included frank blood. On physical examination, the patient had no fever. He appeared generally well. He had no evidence of weight loss. He showed slight rebound tenderness in the upper abdomen. An occult blood test revealed the presence of blood. 1. What would your diagnosis in this case be? 2. What organism is most likely to be responsible for these symptoms and findings? 3. What further testing and treatment are called for?

1. Stomach ulcer 2. Helicobacter pylori 3. There is no direct proven treatment. However, an antibiotic can be prescribed to help inhibit stomach acid production.

Which of the following explains the mechanism of dental cavity formation? (a) Biofilms secrete fluoride, which causes tooth mineralization, resulting in tooth decay. (b) Anaerobic biofilms on the gumline of the teeth displace oxygen gas with anaerobic gasses, leading to bone damage. (c) Biofilms growing on the surface of the teeth metabolize peptides found in the mouth, creating an alkaline environment that dissolves the supporting collagen structure. (d) Biofilms on the surface of the teeth ferment sugars (especially sucrose), and the resulting acid degrades the tooth enamel and damages dentin.

D -- Biofilms on the surface of the teeth ferment sugars (especially sucrose), and the resulting acid degrades the tooth enamel and damages dentin.

Michael was excited when his boss sent him to work on a 6-month project with the Vice President of International Affairs at their corporation in Beijing, China. Before leaving the United States, he visited his family doctor for a complete physical and to receive his immunizations. The physician reviewed Michael's medical history and current lab results and declared that he was a healthy 32-year-old. Michael adjusted well to the move and made many new friends. They would often get together on the weekends to go swimming at a nearby lake, to play volleyball at the local park, or to watch movies and cook dinner. He quickly found that his favorite meal was a stir-fry containing a mixture of pork, fresh raw vegetables, and noodles. He would eat this combination of foods three to four times a week. To his surprise, within 3 months of moving to China, Michael started losing weight. He was not trying to lose weight and when asked about his diet, Michael would say that he ate all the time. At first, he thought the weight loss was just a result of his metabolism adjusting to his new Asian diet and was not a cause for concern. However, after 2 months of continuous weight loss, the non-stop eating was replaced by nausea and slight abdominal pain. At this time, Michael began to think something might be wrong. Michael scheduled an appointment with Dr. Clark at the local medical center. During his appointment, the two of them discussed where Michael had traveled since he had been in China, the types of foods he had eaten, the specifics of his exercise regimen, and his extracurricular activities. They also discussed the lack of symptoms other than the weight loss and recent bouts of nausea. After talking with Michael, Dr. Clark requested that multiple stool specimen be sent to the laboratory for examination. He also ordered serological testing of Michael's blood to determine his antibody titer levels. He was concerned that Michael may have an intestinal parasite infection, even though many are asymptomatic. 1. Why does Dr. Clark request stool samples for examination? Select all that apply. (a) He will have the laboratory prepare the samples for an ova and parasite (O&P) exam. Fresh or preserved stool samples can be observed microscopically for the presence of parasites or their eggs/cysts. (b) Dr. Clark is hoping to find whole adult parasitic worms in Michael's fecal matter. (c) Tapeworms are pathogens of the gastrointestinal tract; as a natural progression of digestion some of the tapeworm pieces will be expelled along with fecal matter. (d) The stool sample will tell Dr. Clark more information about the vegetables in Michael's diet. 2. Which of the following represents the MOST LIKELY route of transmission for Michael's infection? (a) Airborne - Inhalation of parasitic eggs in the air (b) Foodborne - Eating undercooked, unwashed, or otherwise contaminated food that contained parasitic propagules (c) Waterborne - Swimming in a freshwater lake with his friends while he was in China (d) Vectorborne - Bitten by a mosquito carrying parasitic larvae 3. Which of the following organisms is most likely the causative agent of Michael's tapeworm infection? (a) Ascaris lumbricoides (b) Taenia saginata (c) Taenia solium (d) Enterobius vermicularis 4. SKIPPED 5. SKIPPED 6. Michael's blood work reveals an increase in eosinophils, which are granular white blood cells, and his IgE antibodies. Along with the microscopic analysis of the stool specimen, these lab results confirm the diagnosis of a tapeworm infection. Why do we see an increase in the levels of IgE antibody in Michael's serum? (a) IgE is the class of antibodies involved in hypersensitivities such as allergies and parasitic infections. (b) IgE is the class of antibodies found in secretions. (c) IgE is the most abundant class of antibodies in serum (d) IgE is the first class of antibodies to appear after exposure to an antigen. 7. What is the treatment that Dr. Clark will most likely recommend? (a) Oral rehydration to replace fluids because tapeworms cause excessive diarrhea which results in dehydration in the host. (b) Praziquantel or albendazole, drugs that target eukaryotic parasites with minimal side effects in the host. (c) Surgical removal of the tapeworms in Michael's intestinal tract. (d) Dr. Clark will recommend doing nothing because the tapeworm infection is self-limiting and will eventually go away on its own. 8. After treatment, Dr. Clark wanted to monitor Michael's progress to make sure the tapeworm infection was completely cleared. He also ordered Michael to get a computed tomography (CT) scan and a magnetic resonance imaging (MRI) scan. These scans confirmed that Michael's infection was localized to the digestive tract and the tapeworms had not spread beyond that point. Why was Dr. Clark worried about tapeworm infection in other body sites? Select all that apply. (a) When tapeworm larvae escape the stomach, they can travel to other parts of the body such as muscles, the liver, the eye, and even the brain to form cysticerci. (b) Once ingested, the eggs of T. solium migrate to multiple body sites where they develop into structures called hydatid cysts. (c) When the eggs are ingested, the larvae hatch and enter the intestinal glands. As the worm grows, it makes its way to the intestinal lumen where it survives for years by feeding on blood from the host. (d) The presence of T. solium in the brain can result in neurocysticercosis, a serious condition which has symptoms resembling those of brain tumors or epilepsy.

1. A -- He will have the laboratory prepare the samples for an ova and parasite (O&P) exam. Fresh or preserved stool samples can be observed microscopically for the presence of parasites or their eggs/cysts. C -- Tapeworms are pathogens of the gastrointestinal tract; as a natural progression of digestion some of the tapeworm pieces will be expelled along with fecal matter. 2. B -- Foodborne - Eating undercooked, unwashed, or otherwise contaminated food that contained parasitic propagules 3. C -- Taenia solium 6. A -- IgE is the class of antibodies involved in hypersensitivities such as allergies and parasitic infections. 7. B -- Praziquantel or albendazole, drugs that target eukaryotic parasites with minimal side effects in the host. 8. A -- When tapeworm larvae escape the stomach, they can travel to other parts of the body such as muscles, the liver, the eye, and even the brain to form cysticerci. D -- The presence of T. solium in the brain can result in neurocysticercosis, a serious condition which has symptoms resembling those of brain tumors or epilepsy.

On the evening of July 4, 150 people attend the Independence Day celebration and fireworks display hosted by Collintown council co-chairs Cindy and Luke Clark. The celebration is largest that the members of the community can remember. A local restaurant, Bubba-Qs, has catered the event. Attendees have their choice of Texas-style barbecue (pork: dry rub or with Bubba-Qs sauce), coleslaw, baked beans, green salad, beef tacos (with onions, tomatoes, lettuce, cheese, salsa, sour cream, and tortillas), chili, chicken tortilla soup, potato salad, jalapeno cornbread, peaches, homemade vanilla ice cream, and apple pie. Around midnight, both Cindy and Luke begin to experience abdominal cramps and diarrhea. Their symptoms are so severe that they both seek immediate medical attention. Dr. Parker, who is the attending doctor in the emergency room that night, hospitalizes Cindy for severe dehydration. Luke is treated for mild dehydration and released to go home. From midnight to 8:00 in the morning, an additional 38 patients are admitted to the emergency room for symptoms similar to those that Cindy and Luke experience. All of the patients seen by Dr. Parker had attended the Fourth of July celebration. Dr. Parker immediately notifies the director of the Collin County Health Department, Dr. Thompson, to initiate an investigation and collect food samples for microbiological analysis. In addition, Dr. Parker ordered stool cultures on Cindy Clark as well as a reverse passive agglutination (RPLA) test for detecting Clostridium perfringens enterotoxin A. Dr. Thompson's investigation reveals that a total of 40 individuals were given emergency treatment at Collintown Community Hospital. Interviews with these individuals lead to the identification of an additional 65 people who were ill with compatible signs and symptoms but did not seek medical attention. His investigation revealed that all of the ill persons and 45 who did not become ill attended the Independence Day celebration. 1. As an epidemiologist, Dr. Thompson is interested in determining the frequency with which a specified event occurs within a particular population at a certain instant or during a particular period. This measure is known as a rate. In epidemiologic practice, an attack rate is the most commonly used method of determining the extent or frequency with which a disease is experienced by a population of individuals. In this instance, Dr. Thompson is interested in knowing what percentage of the individuals who attended the July 4 celebration became ill. The attack rate is the number of individuals treated and/or had symptoms divided by the number of attending individuals. What is the attack rate of food poisoning among the group who attended the July 4 celebration? (a) 40/150(100)= 26.6% (b) 105/150(100)= 70.0% (c) 65/105(100)= 61.9% (d) 40/65(100)= 61.5% 2. SKIPPED 3. Dr. Thompson is able to obtain leftover food from the celebration for microbiological culture. The food is examined aerobically and anaerobically for the presence of enteric pathogens, staphylococci, and Clostridium perfringens. Clostridium perfringens is identified both in the barbecued pork and in the Bubba-Qs sauce. Cindy's and Luke's stool cultures are negative for enteric pathogens but are positive for C. perfringens enterotoxin A. Based on the microbiological studies, Dr. Thompson is able to confirm that Clostridium perfringens is the cause of the food poisoning outbreak on the July 4 celebration. Clostridium perfringens is a gram-positive, anaerobic, spore-forming organism commonly found in the soil and the gastrointestinal tracts of animals and humans. It is the agent of gas gangrene as well as a self-limited food poisoning and necrotizing enteritis (pigbel disease). Strains can be classified into five toxigenic types (A through E) based on the exotoxin produced. Type A is responsible for nearly all foodborne illnesses and is among the top five most common causes of bacterial foodborne illness in the United States. Clostridium perfringens is very demanding for certain nutritional requirements (amino acids and growth factors) and, therefore, prefers protein-rich substrates. It is commonly detected in meat and poultry that has been boiled, stewed, or roasted and in meat with sauces and gravies. The vegetative cells of the organism can multiply rapidly in food. The resistance of its spores to heat allows the organism to survive incomplete cooking of food. Promotion of spore formation begins in meat that is not evenly cooked, such as large pieces cooked on the bone and subsequently allowed to sit at ambient temperatures. Cases of food poisoning usually develop when contaminated food containing vegetative cells and spores is consumed. Food poisoning is characterized by the sudden onset of diarrhea, accompanied by moderate to severe cramping and midgastric pain. Vomiting and fever are not common occurrences in Clostridium perfringens food poisoning. The absence of fever in most affected individuals helps to clinically differentiate C. perfringens foodborne illness from shigellosis and salmonellosis. The infrequency of vomiting and shorter incubation period contrast with the clinical features of foodborne illness associated with Staphylococcus aureus enterotoxins and fish and shellfish toxins. Illness caused by Bacillus cereus enterotoxin may be indistinguishable from that caused by C. perfringens. Symptoms usually resolve within 12 to 24 hours, and no treatment is required. Oral rehydration or intravenous fluid and electrolyte replacement is provided for patients with severe dehydration, and antibiotic therapy is not indicated. Diagnosis of C. perfringens toxigenic infection is accomplished by the direct detection of enterotoxin in stools. For C. perfringens to be confirmed as the causative agent, a concentration of 100,000 organisms per gram must be detected in the implicated food. Which of the following symptoms is LEAST characteristic of Clostridium perfringens food poisoning? (a) short incubation period (b) moderate vomiting and fever (c) severe abdominal cramping (d) sudden onset of diarrhea 4. The symptoms of C. perfringens type A food poisoning usually begin within 6 to 18 hours after the ingestion of contaminated food. The time depends upon the number of bacteria in the food and the amount ingested; thus, the time of onset is dose dependent. Very large doses of bacteria are required to initiate food poisoning because gastric acid kills most bacteria. Organisms surviving the stomach continue to the small intestine, where the presence of bile salts is thought to stimulate sporulation. It is during the in vivo sporulation that the enterotoxin is produced. Rather than being secreted, as are many microbial exotoxins, Clostridium perfringens enterotoxin (CPE) is released into the intestinal lumen by lysis of the vegetative cells during the end stages of sporulation. Most strains of C. perfringens type A food poisoning carry the enterotoxin gene on the bacterial chromosome. Expression of the cpe gene is regulated by sporulation. Large amounts of toxin can be produced during sporulation. Once released into the intestinal lumen, CPE binds to integral membrane proteins called claudins associated with the tight junctions (TJ) of the epithelial cells making up the intestinal villi. The TJ serve as barriers defining the apical and base membrane compartments and function as a gate in regulating permeability across the epithelial layer. Binding of CPE inhibits the absorption of fluid and ions across the epithelium. The CPE forms a complex with claudin on the cell membrane surface, called a small complex. Six of the small complexes on the cell membrane then aggregate to form a larger complex known as a pre-pore that inserts into the cell membrane to make an active pore. Active pore formation results in calcium influx, which leads to cell death due to activation of a proteolytic enzyme known as calpain. The death of intestinal epithelial cells leads to progressive loss of epithelial lining of the villi, causing fluid to be secreted into the lumen of the intestine. An additional effect of CPE is increased myoelectrical activity of the intestine, which leads to the abdominal cramping associated with C. perfringens food poisoning. Which of the findings listed below support the hypothesis? Select all that apply. (a) Oxidative metabolism of glucose by ileum cells occurs at a constant rate as toxin levels are increased. (b) Histological observation indicates that morphological alteration and sloughing of epithelial cells occurs up to a maximum of 1000 units. (c) Protein levels within the ileum loop fluid are increased up to 1000 units of toxin. (d) Increasing levels of sodium, potassium, bicarbonate, and chloride ions, as well as water, are secreted as toxin concentrations are increased from 25, 50, 100, and 150 units. 5. SKIPPED 6. Dr. Thompson's inspection of Bubba-Qs reveals a problem in the storage of the roasted meat. The pork served at the restaurant was stored in a large walk-in cooler. Even though the temperature of the coookler is 35 degrees F, the cooler could not have maintained large quantities of meat at or below 45 degrees F because of the insulating effects of large volumes of food and inadequate movement of air. The meat found in the cooler at the time of the inspection has an internal temperature of 85 degrees F although it was placed in the cooler 4 hours previously. Dr. Thompson notes other problems, as well: The sauce (which was made from meat drippings, plus brown sugar and spices) was prepared on an overcrowded steam table, and its temperature at the time of inspection is 112 degrees F. The meat was transported to the July 4 celebration in foil-covered pans stacked in the back of the catering van. The sauce was transported in plastic-lined Styrofoam buckets. No provision was made for reheating food items delivered to the event. Food was maintained at ambient temperatures. The restaurant is cited for food safety violations, and the following recommendation is made. Foods associated with C. perfringens food intoxications, such as meats, poultry, and sauces or gravies, should be cooked to an internal temperature of at least 145 to 165 degrees F and maintained at a temperature above 140 degrees F or cooler than 41 degrees F after cooking. Meat dishes should be served hot right after cooking, and any leftovers should be reheated to at least 165 degrees F before they are served. Any leftover foods should be refrigerated after they are removed from heating units and serving tables. So that appropriate cooling temperatures are reached, the food items should be divided into small quantities for refrigeration. Which of the following findings are key to the cause of the outbreak? Select all that apply. (a) The cooler was not maintained at an appropriate temperature. (b) The sauce was prepared on an overcrowded steam table and, as a result, did not reach an appropriate temperature to kill any organisms. (c) Large quantities of meat were prepared and kept warm for a long time before they were served. (d) The meat was not cooked properly.

1. B -- 105/150(100)= 70.0% 3. B -- moderate vomiting and fever 4. B -- Histological observation indicates that morphological alteration and sloughing of epithelial cells occurs up to a maximum of 1000 units. C -- Protein levels within the ileum loop fluid are increased up to 1000 units of toxin. D -- Increasing levels of sodium, potassium, bicarbonate, and chloride ions, as well as water, are secreted as toxin concentrations are increased from 25, 50, 100, and 150 units. 6. B -- The sauce was prepared on an overcrowded steam table and, as a result, did not reach an appropriate temperature to kill any organisms. C -- Large quantities of meat were prepared and kept warm for a long time before they were served.

One summer in the late 1990s, a group of tourists from the United Kingdom became ill after they all stayed at the same hotel in Greece. Epidemiologists conducted surveys among all the people who had stayed at the hotel during the two-and-a-half-week period in which people were reporting their illnesses. They did this in an attempt to determine the cause of the symptoms, which were primarily diarrhea and nausea. They surveyed 239 people; 224 of them reported having been ill while they were still on vacation or shortly after their return. Their diarrheal symptoms lasted 10-15 days. Seventy of the 224 people who reported illness were classified as having definite cases of gastrointestinal disease. A case was called "definite" when a pathogen could actually be recovered from their stool. Of these, the vast majority tested positive for one particular microorganism. 1. Microscopic analysis of the stool samples revealed the presence of small oval-shaped structures, with defined outer walls and two to four nuclei inside that looked like seeds. What is your diagnosis? 2. What organisms should be included in the differential diagnosis of this infection? 3. What feature of the symptoms suggests that the causative organism is not likely to be Staphylococcus aureus? 4. Epidemiologists interviewed the patients about their vacation activities and food intake to try to identify the environmental source of the infection. There was no relationship between illness and a person's attending one of the scheduled children's activities at the hotel. Only two types of food available in the dining room seemed to be associated with the illness: raw vegetables and salads. There was also a statistically significant relationship between illness and having consumed orange juice made from a mix (with hotel water). So what was the likely source? 5. Why would an epidemiologist even ask about a person's attendance at children's activities? 6. Are there any symptoms that would help to distinguish this kind of diarrheal illness from others?

1. Giardiasis 2. E. coli, Staph infection, Salmonella, Shigella 3. The diarrhea lasting for 10-15 days. 4. The hotel's water supply is the likely source. 5. Children may have contaminated their hands and passed it along to others through fecal matter. 6. Fowl-smelling flatulence and needing an anti-protozoan medication.

Last week you were on a clinical rotation at the local hospital as part of your second-year nursing program. You spent most of your time following nurses as they went about their duties from bed to bed, and listening to conversations between doctors and nurses about patients. Then, one day one of the nurses who had just emerged from his fourth trip to the bathroom collapsed behind his desk. He had been losing weight and today looked especially pale. You ran to get the attending physician who was just across the hall. He took one look at the prostrate nurse and said something like "see dif" to the nursing instructor who had arrived on the scene. She replied that he had been on multiple antibiotics for the past few months in attempt to treat a particularly nasty sinus infection. After the sick nurse is transferred to a bed, your instructor asks you for a written report on the condition. You didn't want to admit that you weren't really sure what condition was involved here, so you figured you could look it up in your books or on the Internet at home. 1. Your Internet search of all kinds of different spellings of "see dif" yields nothing. What section of your microbiology text would likely contain the help you need? What clues lead you in that direction? 2. Now that you've found the right category of infections, can you identify what "see dif" is? 3. Your book has only a small paragraph on this infection. But now you know what to search for on the Internet to find more information. Your instructor wants you to report on the epidemiology of the infection. You find that it is referred to as an opportunist and this accounts for its epidemiological patterns. First of all, what is an opportunist? 4. Part of an epidemiological description of an infection involves knowing who is most often affected by it. Let's consider opportunistic infections as a group. People in which age groups are most likely to suffer symptoms from an opportunistic infection? 5. In this case the affected nurse is in his mid-30s. Is it his age or something else that predisposes him to the infection? Discuss. 6. What is the major virulence factor for this microorganism?

1. The GI bacteria section. 2. Clostridium difficile 3. An opportunist organism takes advantage of a suppressed immune system or other weakened defenses. 4. Infants/young children and the elderly 5. Something else. The nurse is not classified in either the very young or elderly. It is most likely he has an underlying condition that makes his immune system weaker. 6. This virus is an endospore former which produces an actotoxin to disrupt the actin's ability in the intestinal epithelium.

Your teenage patient presents with muscle weakness and is unable to move her legs. She notes that yesterday she felt a tingling sensation in her feet. Three weeks prior, the patient had a severe diarrheal illness. Which of the following is the most likely mechanism through which the patient contracted this illness? (a) Eating undercooked chicken (b) Consumption of unpasteurized juice (c) Heavy antibiotic usage (d) Consumption of water contaminated with human feces

A -- Eating undercooked chicken

Which of the following virulence factors are used by Shigella to facilitate development of disease? (a) Induction of endocytosis (b) Endospore production (c) Actin propulsion system (d) Toxin production

A -- Induction of endocytosis C -- Actin propulsion system D -- Toxin production

Which of the following are virulence factors used by Helicobacter pylori to facilitate the development of stomach ulcers? Select all that apply. (a) Polar flagella (b) Production of Shiga toxin (c) Production of endospores (d) Production of VacA toxin

A -- Polar flagella D -- Production of VacA toxin

Which of the following provides the best definition for the term dysentery? (a) Inflammation of the stomach (b) Diarrhea accompanied by pain, blood, and/or mucus (c) Low blood volume due to loss of blood or severe dehydration that can lead to organ failure (d) Inflammation of the intestines

B -- Diarrhea accompanied by pain, blood, and/or mucus

Two days after disembarking on a Caribbean cruise, twenty percent of the passengers aboard an American cruise ship became violently ill with profuse vomiting and diarrhea. Gastrointestinal symptoms lasted up to 3 days. Patients ranged in age from toddler to senior, and the majority of those infected were up-to-date on all vaccinations. Which of the following infections was the most likely cause of illness aboard the ship? (a) Hepatitis B Virus (b) Rotaviral gastroenteritis (c) Norovirus gastroenteritis (d) Hepatitis A Virus

C -- Norovirus gastroenteritis

Which of the following best describes the role of mucosa-associated lymphoid tissue (MALT)? (a) Protein digestion (b) Fat digestion (c) Phagocytic protection from pathogens and mediation of immune responses (d) Metabolism of drugs and toxins and removal of bilirubin

C -- Phagocytic protection from pathogens and mediation of immune responses

In a single day, two 19-year-old women and one 20-year-old man sought treatment at a university health clinic, complaining of acute diarrhea, nausea, and vomiting. No blood was found in their stools. One of the women was found to have a urinary tract infection. All three had eaten lunch at a nearby health food store the previous day. The man had a sandwich with tomato, avocado, sprouts, pickles, and sunflower seeds. One woman had a pocket sandwich with turkey, sprouts, and mandarin oranges; the other woman had the lunch special, described in the menu as a "delightful garden salad of fresh organic lettuces, sprouts, tomatoes, and cucumbers with zesty raspberry vinaigrette dressing." All had bottled water to drink. 1. Which food is the most likely source of the infection? (a) sprouts (b) tomato (c) turkey (d) avocado 2. Which of the following media is used to isolate Gram-negative organisms? (a) blood agar plate (b) tryptic soy agar plate (c) MacConkey agar plate (d) mannitol salt agar plate 3. The organism isolated from the sprouts is oxidase negative, motile, ferments glucose and lactose, and cannot utilize citrate. What organism is it? (a) Salmonella enterica (b) Escherichia coli (c) Enterobacter aerogenes (d) Shigella sonnei 4. What is the best way to prevent the spread of this infection? (a) All food handlers are required to wash their hands thoroughly after sneezing. (b) All food handlers are required to clean restrooms at the beginning of their shift. (c) All food handlers are required to wear gloves to protect themselves from any potential bacteria in the lunch meat. (d) All food handlers are required to wash their hands thoroughly after using the restroom. 5. What is the recommended course of therapy? (a) oral fluids (b) soft food diet (c) intravenous fluid replacement (d) antibiotics

1. A -- sprouts 2. C -- MacConkey agar plate 3. B -- Escherichia coli 4. D -- All food handlers are required to wash their hands thoroughly after using the restroom. 5. A -- oral fluids

A 43-year-old immigrant from Thailand reports to a clinic with his 9-year-old son, who has had bloody diarrhea with mucus, stomach pain, and a fever for the past 24 hours. He reports that his son was healthy when they arrived in the United States a week prior to the start of his symptoms. Round protozoan cysts are subsequently microscopically identified in the boy's stool. 1. Which protozoan disease would be responsible for the symptoms seen in this patient? (a) enterohemorrhagic E. coli (b) amebic dysentery (c) giardiasis (d) cryptosporidiosis 2. If not handled promptly with the correct treatment regime, which of the following infections may develop and be considered as life threatening? (a) oral/genital thrush (b) conjunctivitis (c) luminal amebiasis (d) extraintestinal amebiasis 3. Along with intravenous rehydration, many of the medication groups listed below may be used for secondary infections. But which group must be used if the infection is to be controlled? (a) antiprotozoan medications (b) antidiarrheal medications (c) antibacterial medications (d) antifungal medications 4. What would have been the possible source for this patient's infection? (a) The child was in contact with someone who is currently suffering from amebiasis. (b) Contaminated water in Thailand was used for drinking or cooking. (c) It is impossible to tell without more travel or diet information. (d) Contaminated water here in the United States was used for drinking or cooking. 5. Which species of amoeba would be considered the causes this patient's disease? (a) Entamoeba histolytica (b) Entamoeba coli (c) Acanthamoeba castellanii (d) Naegleria fowleri

1. B -- amebic dysentery 2. D -- extraintestinal amebiasis 3. A -- antiprotozoan medications 4. B -- Contaminated water in Thailand was used for drinking or cooking. 5. A -- Entamoeba histolytica

Two patients--a woman and her husband, ages 23 and 22, respectively--arrive at the health clinic one morning. They report having had severe abdominal cramps, grossly bloody diarrhea, nausea, and fever for 48 hours. Cultures of stool samples grown under microaerophilic, capneic conditions contain comma-shaped, Gram-negative bacilli. Both the patients are lactovegetarians and report being part of a "cow leasing" program at a local dairy in which patrons lease part of a cow's milk production so that they can drink natural, whole, raw milk. The couple devised the program so that they and several neighbors could circumvent state regulations prohibiting the sale of unpasteurized milk. Investigators obtained and cultured a milk sample from the dairy's bulk milk tank. 1. What is the most likely cause of this couple's disease? (a) Mycobacterium tuberculosis (b) Escherichia coli (c) Campylobacter jejuni (d) Salmonella typhi 2. How did this couple become infected with C. jejuni? (a) ingestion of contaminated, raw milk (b) ingestion of contaminated strawberries (c) drinking bottled water (d) ingestion of turkey leftovers 3. What is the word used to refer to diseases transmissible from animals to humans? (a) endemic disease (b) epidemic disease (c) notifiable disease (d) zoonoses

1. C -- Campylobacter jejuni 2. A -- ingestion of contaminated, raw milk 3. D -- zoonoses

Jane is a pediatric nurse at the local hospital. She has twin daughters, 10 months old, who keep her extremely busy. One day, Jane noticed one of the twins acting unusually tired. She took the child's temperature and noted it was 101 degrees Fahrenheit. As Jane was changing the girls' diapers later that afternoon, she noted the same twin showing loose and bloody stool. Alarmed, she immediately scheduled an appointment with her pediatrician for the next morning. The pediatrician requested a stool sample from the next diaper change. He began talking to Jane about how to handle raw eggs and poultry. But she interrupted him, explaining her professional background, and that she knew how intestinal pathogens could be transmitted through food. She was sure her food handling was not suspect. She mentioned that the previous owners of her house raised free-roaming chickens. The pediatrician did not prescribe any antibiotics for Jane's daughter, and sent them home waiting for culture results. When Jane arrived home, she began to retrace all the places she and her twins had visited, as well as, all the foods they had eaten for the past week. For the most part, they had stayed home and played either in the house or the yard. A babysitter comes to the home during the week to watch the twins while Jane goes to work. She usually feeds the twins from the same jars of baby food or cuts up soft fruit for them to feed themselves. Jane liked having the twins outside, but it was getting tricky to keep them on the blanket. They wanted to crawl everywhere. She remembered how she had caught the one twin a couple of days ago stuffing clover leaves into her mouth. She had tried to remove all the leaves; however, later that day she found another leftover leaf in the child's mouth. 1. Why did the pediatrician assume Jane was mishandling raw eggs and poultry? (a) There are no other clear sources of infection based on the patient's case history. (b) Chickens are the reservoir of the most common pathogen of foodborne illness. (c) The girl's exhibited symptoms align with campylobacteriosis and salmonellosis, diseases caused by gastrointestinal pathogens that are known to be associated with poultry. (d) Gastrointestinal pathogens are only transmitted through the fecal-oral route, often from ingestion of contaminated chicken products. 2. Is the pediatrician suspecting a bacterial or viral pathogen? What tests will help identify the causative pathogen? (a) A viral pathogen is suspected. Blood tests that detect patient anti-viral antibodies are commonly used for diagnosis. (b) A bacterial pathogen is suspected. A microscopic examination of cysts or trophozoites from patient stools will help to identify the pathogen. (c) A bacterial pathogen is suspected. Stool samples from infected individuals should be sent for growth culture analysis. (d) A viral pathogen is suspected. Reverse transcription polymerase chain reaction should be performed in order to detect RNA in stool or vomit samples from infected patients. 3. Based on information provided, what is another piece of evidence that may support Jane's claim of safe food handling? Select all that apply. (a) The sick twin had stuffed clover leaves into her mouth, making the clover leaves a suspected source of infection, as opposed to a contaminated food item or preparation area. (b) Due to rigorous food safety testing, raw poultry and eggs are not common sources of foodborne infections in the United States. (c) Only one of the twin daughters is ill, yet both children most likely ate the same food items (the fruit and baby jar food item). (d) Foodborne infections are not typically acquired from mishandling of food. 4. Was the pediatrician negligent in not prescribing antibiotics? Why or why not? (a) Yes. Antibiotic therapy should have been prescribed immediately to limit the progression of disease. (b) No. Antibiotic therapy is not recommended for cases of food poisoning. (c) No. Supportive therapy is the suggested treatment for mild cases of several bacterial diseases, including the one presented in the case study. (d) No. Given that the pathogen is viral, antibiotics would not be an appropriate treatment for the infection. 5. If you were an epidemiologist looking for the source of the pathogen, what samples would you collect at Jane's house?Select all that apply. (a) Food preparation areas (such as kitchen countertops), food preparation tools (such as knives used to cut food), and consumed food items (including the baby jar food) (b) Stool sample of caretakers (c) Disinfectant used to clean kitchen surfaces (d) Soil sample (including clover sample) 6. How does the child chewing on clover leaves impact the list of suspected potential pathogens? Select all that apply. (a) The list of potential pathogens should now be limited to only viral agents. (b) Fecal matter from the free-roaming chickens may have contaminated the clover leaves. Thus pathogens found naturally in chicken intestines should be of increasing concern. (c) Only pathogens, whose reservoir is the soil, should be considered. (d) Since only the ill child chewed on the clover leaves, it is now more likely that the clover leaves are the source of infection (as opposed to the raw eggs and poultry). (e) Fecal-oral transmission may now be excluded as a mode of transmission. 7. What other potential symptoms should Jane be looking for in her daughter over the next few days? Select all that apply. (a) Signs of sepsis and septic shock (such as hypotension and tachycardia) (b) Symptoms of dehydration (including fewer wet diapers, little to no tear production, and decreased skin turgor) (c) Anal itching and sleep disturbances (d) Yellowing of the sclera

1. C -- The girl's exhibited symptoms align with campylobacteriosis and salmonellosis, diseases caused by gastrointestinal pathogens that are known to be associated with poultry. 2. C -- A bacterial pathogen is suspected. Stool samples from infected individuals should be sent for growth culture analysis. 3. A -- The sick twin had stuffed clover leaves into her mouth, making the clover leaves a suspected source of infection, as opposed to a contaminated food item or preparation area. C -- Only one of the twin daughters is ill, yet both children most likely ate the same food items (the fruit and baby jar food item). 4. C -- No. Supportive therapy is the suggested treatment for mild cases of several bacterial diseases, including the one presented in the case study. 5. A -- Food preparation areas (such as kitchen countertops), food preparation tools (such as knives used to cut food), and consumed food items (including the baby jar food) B -- Stool sample of caretakers D -- Soil sample (including clover sample) 6. B -- Fecal matter from the free-roaming chickens may have contaminated the clover leaves. Thus pathogens found naturally in chicken intestines should be of increasing concern. D -- Since only the ill child chewed on the clover leaves, it is now more likely that the clover leaves are the source of infection (as opposed to the raw eggs and poultry). 7. A -- Signs of sepsis and septic shock (such as hypotension and tachycardia) B -- Symptoms of dehydration (including fewer wet diapers, little to no tear production, and decreased skin turgor)

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 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? 2. One of your friends acts disgusted and says she'll order a salad instead. Will this guarantee her safety? Why or why not? 3. One of your friends says that her sister gives her baby apple juice every day. Should she stop? Explain your answer. 4. What are the symptoms of E. coli O157:H7 infection? 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?

1. Steaks should be ordered instead of hamburgers because steaks are not processed like hamburger meat. Since steaks are the muscle of the cow, the bacteria on them can be cooked off. 2. No. Salad may also carry the bacteria unless they are treated with boiling water. 3. No, apple juice is not the same as unpasteurized apple cider and apple juice is pasteurized so that the bacteria is killed. 4. Nausea, vomiting, bloody diarrhea, and kidney failure. 5. He should alter his eating habits to cooked meat because E. coli is likely in the meat, but his family may not have been exposed to this strain of E. coli.

Which of the following statements accurately describes a chronic Hepatitis B viral infection? (a) Chronic Hepatitis B viral infections are typically undetectable. (b) Chronic Hepatitis B viral infections can promote cirrhosis and hepatocellular carcinomas. (c) Chronic Hepatitis B viral infections are usually asymptomatic. (d) Chronic Hepatitis B viral infections are typically untreatable.

B -- Chronic Hepatitis B viral infections can promote cirrhosis and hepatocellular carcinomas.

Which of the following statements is true concerning the life cycle of Giardia lamblia? (a) Giardia lamblia infections are typically acquired when a human host ingests water containing trophozoites. (b) The Giardia lamblia cyst stage is the asexual reproductive stage. (c) After ingestion, a Giardia lamblia cyst hatches into two trophozoites in the small intestine. (d) The cyst is the active feeding stage of the Giardia lamblia parasite.

C -- After ingestion, a Giardia lamblia cyst hatches into two trophozoites in the small intestine.

Your patient complains of upper abdominal pain, heartburn, and indigestion. Based on the patient's case history and clinical presentation, you believe that your patient has a stomach ulcer caused by a resident microorganism. You ask the microbiology laboratory to culture the stomach pathogen from a gastric tissue biopsy. Which of the following bacterial genera would you expect the microbiology laboratory to observe in the patient's culture? (a) Streptococcus (b) Neisseria (c) Helicobacter (d) Prevotella

C -- Helicobacter