83

CASE 83


A 63-year-old man awoke early with nausea, vomiting, and confusion and was taken to a local emergency department for evaluation. His illness, which began 5 days prior to arrival at the ED, during a trip to North Carolina, was characterized by fever, chills, sweats, malaise, anorexia, and headache. He had a dry cough for the past 2 days.


No history of chest pain, myalgias, dyspnea, abdominal pain, diarrhea, or skin lesions was reported. Past medical history included hypertension and cardiovascular disease. He did not smoke.



PHYSICAL EXAMINATION



VS: T 39.2°C, P 109/min, R 24/min, BP 110/64 mmHg

PE: On admission, the patient was alert and interactive but spoke nonsensically. Initial pulmonary, cardiac, and abdominal examinations were reported as normal. No nuchal rigidity was observed. He was not oriented to person, place, or time.


LABORATORY STUDIES



Blood



WBC: 8200/μL

Differential: 40% PMNs, 32% bands, 22% lymphs

Platelets: 80,000/μL

Blood gases: pH 7.36, pCO2 34, pO2 68

Serum chemistries: Sodium 133 mmol/L


Imaging


A chest X-ray showed a widened mediastinum (Fig. 83-1).


image

FIGURE 83-1 An admission chest x-ray revealed a widened mediastinum.


(Courtesy of Dr. Paul Southern, Departments of Pathology and Medicine, University of Texas Southwestern Medical Center, Dallas, TX.)



Diagnostic Work-Up


Table 83-1 lists the likely causes of illness (differential diagnosis). Investigational approach may include


• Gram stain and cultures of sputum, pleural fluid, and cerebrospinal fluid (CSF)

• Blood cultures. Gram stain of an unspun peripheral blood smear

• Direct antigen detection in problem scenarios

• In failed investigation of pneumonia, serology for atypical pneumonic pathogens and endemic fungal pathogens

TABLE 83-1 Differential Diagnosis and Rationale for Inclusion (consideration)






Histoplasmosis

Inhalation anthrax

Meningitis (bacterial or viral)

Plague

Pneumonia
Atypical (e.g., Mycoplasma, Chlamydophila)

Typical (e.g., Streptococcus pneumoniae)

Viral (e.g., influenza, adenovirus [ARD], coronavirus [SARS], hantavirus pulmonary syndrome)

Tularemia

Viral encephalitis (HSV-1)

Rationale: The presentation is nonspecific and may be due to a variety of organisms. The most common are usually viral, such as influenza, although influenza is associated with a cough. Widened mediastinum in this type of clinical setting is often seen with histoplasmosis and inhalational anthrax. Mental status changes are distinctly uncommon for most respiratory infections and should prompt evaluation for CNS infection, including meningitis or encephalitis.



COURSE


The patient was admitted to the hospital with a diagnosis of meningitis. CSF analysis showed WBC count 4750/μL (81% neutrophils), red blood cell count 1375/μL, glucose 57 mg/dL (serum glucose 174 mg/ dL), and protein 666 mg/dL. Microscopic examination of the CSF showed many Gram-positive bacilli. The same Gram-positive bacillus was isolated from CSF after 7 hours of incubation and from blood cultures within 24 hours of incubation. After a single dose of cefotaxime, the patient was started on multiple antibiotics to cover potential pathogens. Shortly after admission, he had generalized seizures and was intubated for airway protection.



ETIOLOGY


Bacillus anthracis (anthrax)

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Aug 25, 2016 | Posted by in MICROBIOLOGY | Comments Off on 83

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