CH 19 Microbiology

Eating peanut butter, cantaloupe, chicken products, seafood, spinach, or handling a pet turtle are all sources of infection for which of the following bacteria?

Salmonella enterica serotype Enteritidis

If not handled promptly with the correct treatment regime, which of the following infections may develop and be considered as life threatening?

extraintestinal amebiasis

Amoebae are a group of protozoa that move and feed using __________.

lobe-shaped pseudopods

Which species of amoeba would be considered the causes this patient's disease?

Entamoeba histolytica

What is the best way to prevent the spread of this infection?

All food handlers are required to wash their hands thoroughly after using the restroom.

The organism appears to be

An amoeba

Which of the following statements accurately describes a chronic Hepatitis B viral infection?

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

The organism isolated from the sprouts is oxidase negative, motile, ferments glucose and lactose, and cannot utilize citrate. What organism is it?

Escherichia coli

Which of the following represents the MOST LIKELY route of transmission for Michael's infection?

Foodborne - Eating undercooked, unwashed, or otherwise contaminated food that contained parasitic propagules

Why does Dr. Clark request stool samples for examination?

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. 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.

Which of the following is a plausible mechanism for contracting pseudomembranous colitis?

Heavy antibiotic usage

Why do we see an increase in the levels of IgE antibody in Michael's serum?

IgE is the class of antibodies involved in hypersensitivities such as allergies and parasitic infections.

Which of the following is false of Campylobacter jejuni infections?

Infections are primarily associated with eating undercooked beef or cross-contaminating foods with raw beef juices.

Which of the following media is used to isolate Gram-negative organisms?

MacConkey agar plate

What is the recommended course of therapy?

Oral fluids

How does Helicobacter pylori cause stomach ulcers?

Polar flagella help bacteria burrow into mucosal lining to escape stomach acid, where enzymes decrease the acidity around them, and they release a toxin to kill host cells.

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.

PARTS A-H FOLLOW

Which of the following organisms is most likely the causative agent of Michael's tapeworm infection?

Taenia solium

Why was Dr. Clark worried about tapeworm infection in other body sites?

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. 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.

What do chronic hepatitis infections result in?

cirrhosis, liver failure, or hepatocellular carcinoma

What would have been the possible source for this patient's infection?

Contaminated water in Thailand was used for drinking or cooking.

Which of the following organisms can cause water-borne diarrheal disease?

Cryptosporidium enteritis, Vibrio cholerae, Entamoeba histolytica

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?

Eating undercooked chicken

Drag the symptoms and mode of transmission to the correct organism.

Entamoeba histolytica: fecal-oral, dysentery; Acanthamoeba: keratitis; Naegleria: meningoencephalitis, inhalation

Which of the following are virulence factors used by Helicobacter pylori to facilitate the development of stomach ulcers? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer.

Polar flagella; Production of VacA toxin

Patty returns later and says she found amoeba trophozoites and cysts. Since amoebae are not uncommon in fresh water and they are not generally pathogenic, she has done a serological test using antibodies and, unfortunately, has discovered that the organism is Entamoeba histolytica. Which of the following should be employed to avoid further problems with the Entamoeba histolytica? Select all that apply.

Post warning that the water should be filtered before drinking. Advise people that have been drinking the lake water, but do not have symptoms, to visit their doctor and ask about a prescription for paromomycin. Advise doctors to prescribe iodoquinol to people who have been drinking the lake water and now have diarrhea.

What is the treatment that Dr. Clark will most likely recommend?

Praziquantel or albendazole, drugs that target eukaryotic parasites with minimal side effects in the host.

Compare the anatomy of the tapeworm (Image C) to the anatomy of the roundworm (Image D). Given that both are parasitic worms, which of the following reasons best explains why the tapeworm is flat?

Tapeworms utilize diffusion to absorb nutrients from the host's digestive system.

Which of the following is not a reason why Clostridium difficile is an increasing concern in healthcare settings?

additional modes of transmission have occurred in several isolated cases

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. Which protozoan disease would be responsible for the symptoms seen in this patient?

amebic dysentery

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?

antiprotozoan medications

Which of the following would not result from a C. difficile infection?

hemolytic uremic syndrome

Which hepatitis virus only results in acute infections?

hepatitis A

When "Health Food" Isn't 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. Which food is the most likely source of the infection?

sprouts