Case Study Exercise 4

EXAMPLE:  Sarah, a 19-year-old female has a history of a urinary tract infection (UTI) 4 months prior to admission for which she was treated with oral ampicillin without complications.  Five days prior to this admission, she began to note nausea without vomiting. One day later she developed left flank pain, fevers and chills, and increased urinary frequency.  Sarah noted foul-smelling urine on the day prior to admission.  She presents with a temperature of 101.8o F, and physical examination shows left costovertebral angle tenderness.  Urinalysis of a clean-catch urine sample is notable for >50 white blood cells per high-power field, 3 to 10 erythrocytes per high-power field, and 3+ bacteria.  Urine culture is subsequently positive for >100,000 CFU of a Gram negative, lactose-fermenting rod per ml; this bacterium was indole positive.

            E1.  What do the urinalysis findings indicate?  Explain your answer.  The bacterium responsible for the infection is the most common cause of UTI’s:  What is the pathogen?

            E2.  How do the biochemical reactions help in the diagnosis?

            E3.  Why are urinary tract infections more common in women than in men?  Did this woman have cystitis or pyelonephritis?  Why is it important to differentiate?

A.  48-year-old Timothy has a long history of alcoholism (including alcoholic hepatitis and hallucinosis) and was admitted to the intensive care unit with profound hypotension and gastrointestinal bleeding.  He was intubated and given IV fluids and transfused with packed erythrocytes.  He remained intubated and ventilator-dependent for several weeks.  He developed fevers and was treated with broad-spectrum antibiotics.  Culture of his tracheal aspirate initially showed Staphylococcus aureus.  After further antibiotic therapy, Gram stain of Tim's tracheal aspirate showed polymorphonuclear leukocytes and Gram negative rods.  His chest radiograph demonstrated an infiltrate and changes consistent with multiple small abscesses.  Culture of the tracheal aspirate yielded a heavy growth of an oxidase-positive, beta-hemolytic, lactose nonfermenting rod that produced a greenish hue on the culture plates.

            1.  What is the likely agent of infection?

            2.  This organism produces an exotoxin that is similar to the exotoxin of which other bacteria?  How do these toxins act on host cells?

            3.      This organism was isolated after Tim received a prolonged course of broad-spectrum antibiotic.  Where is the organism usually found in hospitals?  Does it usually cause pulmonary infections in healthy individuals?

  1. Harvey is admitted to the ER in a weakened state with persistent fever and weight loss.  He is HIV-positive and lived in Panama until recently.  Blood work demonstrates reduced WBC, RBC and platelet counts.  Bone marrow aspiration reveals decreased WBCs and an ascomycete yeast. The yeast produces numerous macroconidia when cultured on PDA.

4.      What is wrong with Harvey?  Explain your reasoning.

5.       What environmental source is associated with the organism and why?

6.      Name two states in the U.S. where it is endemic.

  1.  Cathy, a teen-ager develops generalized seizures.  A CAT scan reveals a single brain lesion consistent with a tumor.  Biopsy of the lesion shows a cysticercus.  Cathy lives in Texas and has never traveled outside of the state.

7.      What is the etiologic agent causing Cathy's disease?

8.      How is this transmitted?

9.      How might this be prevented?

  1. While on a trip to Galveston to visit the Strand, Sara consumes raw oysters at a small bay-side restaurant.  Two days later, she has abdominal pain, severe cramping, explosive watery diarrhea and a low-grade fever. Sara recovers in a few days without antibiotic treatment.

10.  What is the most likely culprit (genus and species)?  Support your answer!

11.  If the Sara had “rice water stools,” what species would you suspect?  Support your answer.

12.  How are these diseases prevented?  Be very specific.

  1. One-year-old Valerie is admitted to the hospital in December with fever and dehydration.  Her parents report she has a 1-day history of fever, diarrhea, vomiting and decreased urination. On examination Valerie has a fever, rapid pulse and breathing, and is drowsy. Physical examination is unremarkable except for hyperactive bowel sounds.  EIA confirmed rotavirus infection.

13.  How would you treat Valerie and why?

14.  Is there a current vaccine?  Explain the recent history of the vaccine.

15.   Compare and contrast incidence statistics of the U. S. and the developing world.

  1. On July 8, Edith is given an antibiotic for presumptive sinusitis.  However her condition worsens and she is unable to eat for four days because of severe pain and tightness of the jaw.  On July 12, she is admitted to the ER with severe facial spasms.  Edity reports that on July 5, she had gotten a puncture wound at the base of her big toe; she cleaned the wound but did not seek medical attention.

                   16.  What is the disease?  Explain your reasoning.

17.  What is Edith's prognosis?

18.  What causes the symptoms?

19.  Are other patients at risk of transmission from Edith? Explain your reasoning.

20.  How is this disease prevented?  Be very specific about the timing.