Case History:

A Delayed Diagnosis

Background

A 25-year-old New Mexico rancher was admitted to an El Paso Hospital on February 12 because of a two-day history of headache, chills, and fever (40C). The day before admission, he began vomiting. The day of admission, an orange-sized swelling in the left axilla was noted. A lymph-node aspirate and a smear of peripheral blood were reported to contain gram-positive cocci, often in pairs. Under the assumption that a gram-positive organism had caused the patient's illness, he was given cefoxitin. The man was acutely ill. Within a few hours of admission, he had a cardiopulmonary arrest. During resuscitation efforts, he vomited and aspirated his vomitus; a chest X-ray showed bilateral infiltrate.

Additionally, the patient bled from several body sites. The patient died within 6 hours of admission. In the 2 weeks prior to becoming ill, the patient had trapped, killed, and skinned 3 kit foxes, 4 coyotes, and 1 bobcat. The patient had cut his left hand shortly before skinning the bobcat on February 7.

After his death, biochemical testing of a gram-negative rod isolated from blood cultures identified the etiology as Enterobacter agglomerans.

Questions

1. Identify the following periods: incubation, prodromal, illness, decline.

2. Identify the etiologic agent of this disease. Briefly explain how you arrived at your conclusion.

3. What microbiologic tests would you perform to verify the etiology?

4. How might the patient have been treated between February 7 and 12?

5. What special precautions needed to be taken by the hospital and mortuary personnel?

The Solution

1. Incubation period: February 7-10.

Prodromal period: February 10.

Period of illness: February 11-12.

Period of decline: None; the patient died.

2. Yersinia pestis. The organisms may have been interpreted as being cocci or diplococci because of

(1) the tendency of Y. pestis to assume a bipolar appearance when stained and

(2) the rapid division of this coccobacillary organism, which might have given the impression that the dividing organisms were in pairs. Y. pestis and some strains of E. agglomerans are relatively inactive biochemically and may be difficult to differentiate. Other characteristics, such as colonial morphology, growth characteristics in broth, and motility, will aid in the differentiation of these organisms.

3. Culture and fluorescent-antibody stains.

4. With antibiotics.

5. The patient should have been placed in isolation, and special isolation procedures should have been used in handling his body fluids. Personnel should receive antibiotic prophylaxis.

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