Case Study Exercise 2


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.  An 18-year old sexually active female comes to her GYN for a routine physical and PAP smear. Her physician notices Mariana has 4 tiny, flat, painless genital warts in the labial area and asks Mariana if she has noticed them.  Mariana did not know they were there nor when they might have appeared. Her PAP smear shows no abnormalities.  This condition is caused by a naked, double-stranded DNA virus.

1.  In this age group, how common is this disease?

2.  Why are genital warts a cause for concern?

3.  Describe the status of the current vaccine and its use.

B. Douglas is admitted to the hospital to receive IV antibiotics for treatment of folliculitis.  He began a second round of antibiotics a few days ago, this time ampicillin. Doug has had diarrhea, abdominal cramps and fever.  Blood tests reveal high WBC counts.  Stool samples show patches of colonic epithelium.  The infectious agent is found to be a Gram positive, endospore-forming bacillus, producing toxins A and B.

4.  What is causing Doug's infection?  Explain your conclusion.

5.  What is this disease called, as evidenced by the epithelial tissues found?

6.  What treatment would you prescribe to cure his current problem and why?

C.  Nineteen-year-old Samantha presents to a clinic with low grade fever and abdominal pain that has been present for 2 days.  Samantha has had a vaginal discharge for the past 4 days and was sexually active with multiple partners in the last several months but used no protection.  Urine is collected for a Genprobe assay testing for both chlamydia and gonorrhea.  Samantha is given a ceftriaxone injection and a doxycycline prescription for 2 weeks.

7.  DNA probe assays are routinely used from urine specimens for teenagers because they are easily obtained.  Why does the physician also do a culture on Samantha?

8. This woman likely has PID.  If left untreated, many cases result in infertility.  How is this caused?

9.  In this case, the culture is positive for a Gram negative diplococci.  What is the likely etiologic agent?

D.  A 42-year-old airline pilot Dave presents to the clinic with shortness of breath, fever and chills.  Dave is diagnosed with pneumonia and treated with ceftriaxone after collecting blood and sputum cultures.  Because he has recently traveled to a region endemic for malaria, thick and think blood films are sent to rule out Plasmodium and they test negative.  When Dave's condition continues to decline, he is send to a tertiary care center.  Blood cultures are negative.  Sputum cultures reveal only normal flora.  Bronchial lavage (BAL) is finally ordered and the direct microscopic examination using a calcoflour white/potassium hydroxide prep reveals moderate-sized yeast with broad-based buds.  He is given amphotericin B and recovers.

10.  What is the suspected organism...give evidence why you believe this.

11.  What tests does the laboratory use to confirm this pathogen? Be specific.

12.  Where did Dave likely acquire this infection and why?

E. Sal returned from Africa 12 days prior to his hospital admission.  He has been there for 6 months working as a civil engineer building roads in Rwanda, Zaire and Uganda.  A week before, Sal began suffering with chills, cough and myalgia.  Three days ago, he had episodes of fevers and chills, three times a day.  On admission, Sal is stuporous and shows mental changes.  Blood work shows lowered WBC and platelet counts.  His hematocrit value is about half the normal level and his bleeding times are very prolonged.  A sporozoan parasite is recovered from the blood, showing a characteristic “ring form.”  Despite treatment, Sal eventually became comatose and died.

13.    What was wrong with Sal?  Give your thinking about how you got to your answer, including the genus and species.

14.  Of what significance are the mental changes?

15.  How could Sal’s condition have been prevented?

16.  Describe two ways to prevent the transmission of this disease.

F.  Forty-year-old Beatrice notices an ulcer on the distal aspect of her right third finger approximately 12 days prior to admission.  She develops chills and fever and is treated with oral penicillin without success.  Bea is then referred for admission to this hospital. On physical examination, Bea is an obese female in moderate distress.  Her temperature is 40o C, and her respiration 18/min.  Remarkable physical findings include an excoriated, ulcerated lesion of the right third finger and associated epitrochlear and axillary lymphadenopathy.  Cultures (including blood and wound surface) are negative.  Retrospective questioning reveals that Bea had butchered a rabbit 1 week prior to the onset of her illness.

17.  What pathogen is the most likely etiologic agent?

18.  Give two reasons why the laboratory must be notified in advance when attempting to isolate this organism from tissues.

19.  Serologic diagnosis is attempted in this patient.  Her initial titer against this bacterium was 320, and a follow-up titer 2 weeks later is 2,560.  How much of a rise in titer does this represent, and does such a rise indicate disease? 

20.   Describe two other means of transmission that might occur with this pathogen.