Clinical Topics Conference: Chapter 9c, Infectious and Parasitic Diseases II

Click on a hyperlink.
  1. Candidiasis
  2. Histoplasmosis
  3. Zygomycosis
  4. Toxoplasmosis
  5. Malaria
Case 1: Candidiasis

Clinical vignette 1

A 69-year-old man was admitted 22 days before death with a complaint of intermittent obstruction of the colon of 15 years duration. For about one year before death he developed increasing constipation with diminution in the size of his stools; he also began to have perineal and rectal pain. There was melena and bright red blood in his stools. Rectal examination on admission revealed a rough, bleeding obstructive, annular neoplasm 2.5 cm above the anus. In preparation for surgery, he was given neomycin 1 gm, by mouth, before the operation. Eighteen days before death the lesion was resected. The patient did well postoperatively, and 15 days before death was given a three day course of chemotherapy with nitrogen mustard (an old chemotherapeutic agent) for a total dose of 30 mg. Postoperatively he also received penicillin, 600,000 units four times a day and streptomycin, 0.5 gm twice a day by injection. Several days before death, he developed mild diarrhea, abdominal discomfort and fever. Clinically, a urinary tract infection was suspected, since urine contained numerous red blood cells and white blood cells, which were absent at the time of admission. A white blood cell count on the following day revealed a leukopenia of 1,750 white blood cells and a hemoglobin of 8.2 gm. When rechecked the next day, the white blood count had fallen to 850/mm3 and subsequently it fell to about 400. He remained febrile in spite of his medications. His abdomen became distended and tender, and diarrhea persisted. He became disoriented. He had temperature elevations from 102 oF to 105 oF, and died on the twenty-second hospital day, three days after the leukopenia was discovered.

At autopsy, the gastrointestinal tract from epiglottis to colostomy site was lined by a 1mm tenacious, greenish-yellow membrane. The underlying bowel wall was hyperemic and in many areas frankly hemorrhagic. The ileum was dilated grossly hemorrhagic and necrotic in some areas. Metastatic carcinoma was noted involving the liver and the adrenals. Whitish plaques were also noted, involving most of the esophagus.

Discussion topics

  1. List the factors which contributed to the patient's eventual pseudomembranous colitis.

  2. What methods would be effective in preventing overgrowth of fungi and anaerobes in the GI tract?

  3. The lesions in the esophagus proved to be candidiasis histologically. What are the other manifestations of candidiasis; which areas do they involve?

  • Go to top
    Case 2: Histoplasmosis

    Clinical vignette 2

    The patient was a 6 year old boy from the Kansas City area who was well until 1 month before death. His past medical history was said to be non-contributory. He was not immunocompromised. His social history was remarkable for living on a farm, and for the fact that he cleaned out a dusty chicken coop 10 days before becoming ill.

    The patient developed daily fevers from 104 - 106 oF, frequently followed by a drop in fever to 95 oF. He failed to respond to numerous antibiotics prescribed by a local physician. Ten days before death he was hospitalized for a diagnostic workup. Severe leukopenia, hepatomegaly, and splenomegaly were noted on admission. Diagnosis was made four days after admission by bone marrow biopsy and culture. Despite anti-fungal therapy with amphotericin, the patient expired after 6 days of treatment. Autopsy disclosed widely disseminated histoplasmosis.

    Discussion topics

    1. Discuss the transmission of histoplasmosis, and how this boy might have acquired the infection.

    2. Discuss the geographic pathology of histoplasmosis.

    3. Is this a typical case of histoplasmosis?

    4. What other disease is histoplasmosis often mistaken for?

    5. What is the best way to make a diagnosis of disseminated histoplasmosis?
  • Go to top
    Case 3: Zygomycosis

    Clinical vignette 3

    The patient was a 58 year old diabetic female who had been hospitalized at a rural hospital for pneumonia. She had been receiving total parenteral nutrition (TPN) because of chronic weight loss and diarrhea, and was, therefore, chronically acidotic. Her diabetes was said to be in good control. She had been treated with various antibiotics for over a week, but did not improve. She developed a paraesthesia on the left half of her face, noticed decreased visual acuity on the left, and ultimately developed a proptotic and fixed left eye. The doctors were perplexed until an infectious disease consultant told them the obvious (to him) diagnosis, approximately 2 weeks after she first began exhibiting symptoms. To add to the tragedy, the doctors had intubated the patient through her nose when she developed respiratory distress earlier that day. The tube was pulled by the infectious disease consultant (much of her sinuses coming with it), and she was re-intubated. Examination of the nose by the infectious disease consultant showed white fungus growing on the turbinates. She was then Life-Flighted to the Medical Center emergently. She was taken to surgery where an orbital exenteration was performed, but she died shortly after surgery and an autopsy was obtained. At autopsy, her lungs were found to be infarcted due to infiltration of pulmonary vessels byRhizopus spp.

    Discussion topics

    1. What group of patients are at risk for rhinocerebral zygomycosis? Why?

    2. What is the proper specimen for diagnosing rhinocerebral zygomycosis (or any tissue fungal infection) in the clinical microbiology laboratory?
  • Go to top
    Case 4: Toxoplasmosis

    Clinical vignette 4

    The patient was a female neonate born by C-section to a 24 year-old Caucasian mother who was G5 P2 Ab3. The baby was born at 25 weeks, 3 days of gestation. Her Apgar scores were 1/5. Her weight was 733 grams and her head circumference was 23 cm. The infant had multiple fetal anomalies noted shortly after admission to the neonatal ICU, including: hydrocephalus with dilation of the lateral and the 3rd ventricles, pericardial effusion, thrombocytopenia (plts 8000), neutropenia (8%), lymphocytosis (78%), neonatal hepatitis (AST 217, ALT 32), periventricular leukomalacia, hematuria, hypoglycemia (38) hyperbilirubinemia (total bili 3.3), respiratory distress, and fetal ascites.

    The maternal history was significant for a "viral" infection at 12-13 weeks of gestation. The mother experienced 2-3 days of fever, tender lymphadenopathy of posterior and anterior cervical nodes x 2 weeks, myalgia, and a 2-3 day rash on the trunk, face, and extremities. This was thought to be consistent with CMV infection.

    Viral and bacterial cultures were obtained. The baby was started on ampicillin and gentamicin. Gancyclovir was recommended, if viral cultures were positive. She also received surfactant for her pulmonary distress. The total bilirubin rose to 11.1 (10.5 unconjugated) by the next day. Acute renal failure also ensued. She received dopamine, FFP, cryoprecipitate, iv immunoglobulin, and packed RBCs. A TORCH titer (on the baby's serum) revealed a positive CMV titer. The serum was referred for a CMV IgM. Five days after birth, given the severe brain injury, all support was withdrawn at the parents' request, and the patient expired. The clinical diagnosis prior to autopsy was congenital CMV infection.

    Discussion topics

    1. Discuss the transmission of Toxoplasma gondii.

    2. Can toxoplasmosis be transmitted to a fetus from a chronically infected mother (IgG positive, IgM negative)?

    3. Discuss some preventive measures for congenital toxoplasmosis, based upon the life cycle, that could be given to pregnant women.

    4. What percentage of fetuses become infected during acute infection of the mother?

  • Go to top
    Case 5: Malaria

    Clinical vignette 5

    The patient was a 20 year old Caucasian coed from Duke University. She had just returned for the fall semester from a summer elective in sub-Saharan Africa, which she took to try to decide if she wanted to be a missionary.

    Shortly after returning home, she complained of severe headache and fever. She remained at home, in bed, with fevers to 104 oF, for 2 days until her mother forced her to seek assistance at the Duke University student health clinic. A primary care physician suspected malaria, and referred her to an infectious disease specialist.

    The ID specialist immediately ordered a Giemsa-stained thick smear, which was positive. The organism is shown in this photo.

    Discussion topics

    1. What subtype of malaria should be diagnosed?

    2. The girl's HMO wants to know if you could treat her as an outpatient. What do you say to that?

    3. The patient was taking chloroquine chemoprophylaxis on her trip. Why did she then acquire malaria? Is drug resistance a problem with this organism?

    References

    1. CDC guidelines on malaria
  • Go to top