Case 1 (3)
A 35-year old man had not been feeling well for a few days with nonspecific aches and pains in his joints and a slight headache. He attributed this to a barbecue he had attended a few days previously, where he also drunk a considerable amount of alcohol. The following day he felt considerably worse with severe colicky abdominal pain, and bloody diarrhea, going to the bathroom 10 times during the day. This persisted overnight and he went to the local E.R. On examination he was noted to be dehydrated and rather pale. He was admitted to the hospital for intravenous rehydration, and blood and fecal samples were sent for culture. He was started on antibiotics, and over the subsequent days he improved with lessening of the symptoms and was discharged home. Some weeks later he began to develop weakness in his feet, which gradually affected his legs. He contacted his primary care physician who admitted him to hospital. Over the subsequent few days, the paralysis affected his upper leg muscles, and gradually over the ensuing weeks slowly resolved with treatment. Fecal culture on selective medium incubated at 42 C in a microaerophilic environment revealed a small, oxidase positive colony that Gram stained revealed to be a small, curved/gullwing Gram negative rod.
1.What is the causative agent? (Genus and species, no abbreviation)
2. What is the disease pathogenesis?
3. How is the disease treated?
Case 2 (5)
An elderly lady, of no fixed abode, arrived at the hospital’s E.R. after having fallen. She was admitted for fixation of a hip fracture . Shortly after admission she developed signs of a chest infection and was started on a cephalosporin, which she remained on for a week. Subsequently she developed profuse watery diarrhea and abdominal pain. A feces sample was sent to the laboratory to test for the toxins of Clostridium difficile, which proved positive and she was commenced on oral vancomycin. Despite treatment, the diarrhea persisted and it also failed to respond to a course of metronidazole. The condition of the patient worsened and a sigmoidoscopy was performed, revealing that she had pseudomembranous colitis. Her clinical condition deteriorated and she developed toxic megacolon and an emergency colectomy was performed. The patient died shortly after the operation.
1.What are the two exotoxins of Clostridium difficile, AND how are they responsible for disease in question?
a.
b.
2. Summarize these characteristics of C. difficile: selective medium, atmosphere for in vitro growth, and Gram stain result.
3.How is the disease diagnosed (methodology) typically when searching for the organism’s toxins in stool?
Case 3 (12)
A 50-year old advertising executive consulted his primary health-care provider because of tiredness, lethargy, and an abdominal pain centered around the lower end of his sternum, which woke him in the early hours of the morning. The pain was relieved by food and antacids. His uncle died of stomach cancer and he was worried that he had the same illness. On examination his doctor noticed that he seemed a bit pale and that he had a tachycardia. His blood pressure was low. He was slightly tender in his upper abdomen but there was no guarding or rebound tenderness. The doctor took blood and feces samples and organized for an upper gastrointestinal endoscopy. The full blood count showed a hypochromic normocytic anemia with a hemoglobin of 8.9 consistent with iron-deficiency anemia. The gastroscopy showed a 3 cm ulcer in the prepyloric region of the stomach. The patient was started on routine treatment for a duodenal ulcer.
1.What is the causative agent? (Genus and species, no abbreviation)
2. What is the host immunological response to the infection?
3. How is the disease diagnosed IN the clinical laboratory?
Case 4 (22)
A 37-year old Hispanic woman, a native of Southern Mexico, went to see her primary care physician after complaining of a persistent rash throughout her body. The woman had three children, was a nonsmoker, and appeared to be well-nourished. Her symptoms had started 5 years BEFORE with spasms, with needle-like pain, in her arms. She also felt tired and stressed and had been initially diagnosed with depression. Her skin examination indicated atopic dermatitis and urticaria and she was prescribed ibuprofen, fluoxetine, and hydroxyzine. Physical examination revealed numerous hypopigmented skin lesions, especially those on her arms, nasal bridge area, cheeks, abdomen, and back and her legs. Her eyebrows had started thinning and she had numbness in her forearm. The patient had a biopsy of skin lesions on the abdomen. Acid-fast bacilli were detected .
1. What is the most likely causative agent? Genus and species, no abbreviation.
2. Describe the two (2) clinical forms of disease caused by this organism?
3. How is the disease managed/treated?
Case 5
A 10 year old Amish child is brought to the emergency room because of high fever and sore throat of six days duration. Examination reveals a temp of 101. There was a dirty gray membrane over the tonsils and posterior pharynx. History reveals, which is typical, that the child has had no infant/childhood immunizations. Culture of the throat on cysteine-tellurite blood agar (CTBA) revealed small gray to black colonies which Gram stained tiny pleomorphic Gram positive rods.
1. What is the identification of this organism? GENUS AND SPECIES.
2. What is the relationship between this organism and the Elek test?
3. Why are some strains of this organism pathogenic and some are not?
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