4. What are the symptoms of E. coli O157:H7 infection?

Vomitting, bloody diarrhea, abdominal cramps, occasional fever
-shiga toxin -producing E coli.

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?

When the beef is ground the bacteria on the surface is mixed into the meat and contaminates it. I would recommend that my friend stick to whole cuts of beef that can be seared on the outside to eliminate the surface bacteria. This would present a safer option to enjoy raw beef with a reduced risk of infection.

Case 2

Last week you were on a clinical rotation at the local hospital as part of your second-year nursing program. On this rotation, your instructor took a hands-off approach and left you on your own for hours at a time. You spent most of your time hanging around at the nursing station, 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?

Chapter 24 Digestive System Infections.

2. Now that you've found the right category of infections, can you can identify what "see dif" is?

C.diff, also known as Clostridium difficile, is a bacterium that causes severe diarrhea and inflammation of the colon. C.difficile gains a foothold in a host when the gut microbiota is disturbed, usually as a result of antibiotic therapy.

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?

An opportunistic microbe is a microbe that takes advantage of a immunocompromised host, for example the nurse was on antibiotic this can lower you immune system and can wipe out good bacteria and can create and opportunity for c-diff to strike.

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?

Elderly or very young

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.

No, the antibiotic made him more susceptible and likely his exposure came from working in the hospital, or he is immunocompromised.

6. What is the major virulence factor for this microorganism?

Endospores are a major virulence factor because they withstand extremes like alcohol-based cleaning solutions and torrents of diarrhea attempting to flush them out of the lower GI. They also have the ability to stay in a dormant state until they are picked up by a new host.

Case 3

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 their son vaccinated against hepatitis B virus (HBV). Pam called you because the doctor had convinced her that it was necessary. 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.

Pam's husband is partially correct. It is true that Hepatitis B can be acquired through sexual contact. However, it can also be acquired through blood contact, from mother to child at birth, shared syringes, or contact with another's bodily fluids such as saliva. It is still quite possible for their child to get infected with Hepatitis B despite not having any type of sexual contact.

2. How severe is this infection for young children?

Not common in children but if exposed HBV can be chronic and cause liver failure and liver disease in babies and young children.

3. Pam says she'll also remind him that in the last year the newspapers have reported at least three hepatitis outbreaks traced to restaurants. Respond to her statement.

Hep A is the one that can be transmitted fecal-oral.

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?

This vaccine is genetically engineered and the antigen is artificially made in a lab. It is actually safer if it is genetically engineered because it cannot turn into a toxin producing antigen like others naturally made in the body

Case 4

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?

Protozoan: Ghiardia lamblia, Giardiasis

2. What organisms should be included in the differential diagnosis of this infection?

It would be standard practice to test for common pathogens associated with food or water contamination, such as E. coli, S. aureus, Shigella, Salmonella .

3. What feature of the symptoms suggests that the causative organism is not likely to be Staphylococcus aureus?

Commonly Staph is on the skin, but Staphylococcus aureus is the cause of most food poisoning. Typical symptoms of staphylococcal food poisoning include severe nausea and vomiting. In this case, the reason S. aureus is not the causative agent is because some of the tourists did not get sick until after returning home from vacation. In staphylococcal intoxication, symptoms start very quickly - about 2 to 8 hours after the contaminated food is eaten.

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 the 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 salad. 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 source?

Contaminated water. Water would likely have been used to wash the vegetables and salad, and water was used to mix orange juice.

5. Why would an epidemiologist even ask about a person's attendance at children's activities?

Children often don't wash their hands after using the bathroom and as we all know, kids "get their hands on everything!" They easily spread infection through fecal-oral transmission.

6. Are there any symptoms that would help to distinguish this kind of diarrheal illness from others?

Ghiardia found in stool. Also the symptoms were no blood, disease lasted longer, diarrhea not described as foul smell.

Case 5

On Christmas Eve of 1998, the Ohio 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 state epidemiologist was aware of a national outbreak of a disease with the symptoms seen in these cases. The symptoms included 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 50 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 included 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 and cold cuts, as the source of the outbreak. A recall of meat processed at a particular plant in Michigan was instituted.

1. What is the most likely causative microorganism in this outbreak?

Listeria monocytogenes

2. Why is this infection associated with processed meats (hot dogs and deli meats), but usually not with hamburger or cuts of meat including pork, beef, or chicken?

L. monocytogenes is able to reproduce and survive well under refrigeration. Therefor, if infected meats such as hot dogs and deli meats are not heated adequately or become occupied by L. monocytogenes after processing, the bacterium can survive and multiply. Typically, hamburger, pork, beef and chicken are heated adequately and the bacterium is killed off in the process. The meat will likely remain un-contaminated as long as the leftovers are refrigerated and eaten within 3-4 days.

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.

Low pathogenicity because it's limitation to high risk groups (pregnant people and neonates)

Case 6

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 watery 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.

Vibrio cholera

2. The doctor's eyes widen and she asks you how you came to that conclusion. What is your reply?

Came from Peru where Cholera is endemic. Also, rice-water stools.

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?

Cholera is not endemic to the U.S. Travel from Peru makes it much more likely. Modern sewage and water treatment have virtually eliminated cholera in industrialized countries.

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?

Rehydration therapy, the primary treatment for cholera patients, refers to the prompt restoration of lost fluids and salts. Antibiotic treatment reduces fluid requirements and duration of illness, and is indicated for severe cases of cholera.

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?

Cholera infection is most often asymptomatic or results in mild gastroenteritis. Approximately one in 20 people will have severe disease, with profuse painless, watery diarrhoea described as 'rice water stools' and vomiting leading to rapid volume depletion. Another family member may have had the disease mildly, infected food brought back. asymptomatic carrier or convalescent carrier.

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?

In most countries, doxycycline is recommended as first-line treatment for adults (including pregnant women) and children. If resistance to doxycycline is documented, azithromycin and ciprofloxacin are alternative options.

Case 7

You went to get a haircut yesterday and your stylist was having a conversation with another stylist in the shop. The second stylist said that her live-in boyfriend of three years just got a blood test and discovered he has hepatitis C. Your stylist shrugged her shoulders and said her boyfriend has never had any symptoms so she wasn't going to worry about it.

1. After the second stylist walks away, your stylist asks you about hepatitis C. Her first question is, "Is it serious?" Answer this question as thoroughly as you can.

Yes, it is chronic and can cause liver damage.

2. How is it transmitted?

Transmitted almost exclusively through blood. It is NOT transmitted through saliva, sneezing, and seldom by sex like with hepatitis B. Blood was not tested until 1992, so many acquired it through blood transfusions. Also, tattoos, body piercings, and injecting illicit drugs.

3. Can she be vaccinated against it?

No vaccine for hepatitis C

4. Your stylist has heard of hepatitis A and hepatitis B, but never hepatitis C. Is it new? Explain.

Hepatitis C was first established in 1988 when able to reliably detect it in the blood. Infection peaked in the 80s so it is relatively new.