Man With High Fever, Headache, and Cough

What's The "Take Home"?
Pearls From Clinical Cases 

A 45-year-old African American man is admitted to the hospital with unremitting fever, severe headache, rigors, and a cough. Three days earlier he had sought medical attention at a health clinic because of malaise, fever, and flu-like symptoms. He was advised to rest, drink fluids, and use acetaminophen. However, his illness worsened despite these measures.

HISTORY

The patient has essential hypertension, which is controlled with an angiotensin-converting enzyme inhibitor. He has no history of heart or lung disease or diabetes. He is a landscaper at a university; his work involves the entire grounds, and he occasionally goes inside classroom and dormitory buildings. He drinks 2 cans of beer per day and has smoked less than 1 pack of cigarettes per day for many years.

PHYSICAL EXAMINATION

The patient appears ill. Temperature is 39.4°C (103°F); heart rate, 120 beats per minute; and blood pressure, 110/60 mm Hg. Respiration rate is 20 breaths per minute without use of accessory muscles. Skin is warm and dry. Chest examination reveals no consolidation. Although tachycardia makes it difficult to perform the heart examination, no grossly pathologic murmurs are heard. Neurologic examination reveals photophobia and probable neck stiffness.

LABORATORY AND IMAGING RESULTS

White blood cell (WBC) count is 19,900/µL with a significant left shift. Hemoglobin level is normal, and platelet count is 106,000/µL. Serum sodium level is 128 mEq/L and chloride level is 92 mEq/L without an anion gap. Serum glucose level is normal. Cerebrospinal fluid (CSF) examination reveals a glucose level of 40 mg/dL, protein level of 110 mg/dL, and WBC count of 3010/µL with 98% polymorphonuclear neutrophils. Gram staining discloses no organisms. A chest radiograph shows a probable right lower lobe infiltrate.

Which statement related to the epidemiology of this patient’s illness is true?

A. The case-rate incidence is increasing.

B. The most likely causative organism is Streptococcus pneumoniae.

C. The case-fatality rate is decreasing.

D. Vaccines have almost eliminated Neisseria meningitidis as a cause in young adults.

What's The "Take Home"?
Pearls From Clinical Cases 

Correct Answer:

B. The most likely causative organism is Streptococcus pneumoniae.

This case illustrates issues involved in the diagnosis and management of community-acquired meningitis. The patient presents with clinical findings consistent with meningitis (ie, hectic fever, photophobia, and neck stiffness); bacterial meningitis is further strongly suggested by the striking CSF findings of a low glucose level, elevated protein level, and polymorphonuclear pleocytosis.

Because Gram staining demonstrated no organisms, one question here is, what is the most appropriate empiric antibiotic regimen to administer before culture results are available (results that may well be negative)? The patient’s history includes several important epidemiologic features that can help with this decision:

•His age (45).

•His ethnic background (African American).

•The paucity of related risk factors (such as immunosuppression or corticosteroid use) in this otherwise healthy 45-year-old man.

Causes of bacterial meningitis. Recent studies confirm that 5 organisms are responsible for more than 80% of meningitis cases: group B streptococci, Haemophilus influenzae, N meningitidis, S pneumoniae, and Listeria monocytogenes.^1,2 The expanded use of effective vaccines—specifically for H influenzae and N meningitidis—has significantly reduced the incidence of infection with these organisms in children, and of meningitis in general in the United States.² However, the correlation between patient age and causative organisms remains strong.

Group B streptococcal infection still chiefly affects infants younger than 2 months.

The incidence of listerial infection peaks in 2 age groups: infants younger than 1 month and persons older than 60 years. The infection also occurs frequently in
immunocompromised persons (eg, those taking corticosteroids or those with lymphoma), but would be unlikely in this patient.

N meningitidis infection might be suggested by this patient’s employment at a university. Small outbreaks of meningococcal infection are regularly reported among students at colleges and universities; in fact, N meningitidis remains responsible for most cases of meningitis among children and young adults.² As mentioned, the use of vaccines for N meningitidis has markedly reduced the incidence rate by about 58%,² but it has not eradicated this organism, which remains the most common cause of meningitis in the pediatric–young adult population. Thus, choice D is an overstatement and is not correct. The patient’s age makes meningococcal infection unlikely in any event. Furthermore, although he works at a university, his exposure to N meningitidis would be sporadic at most because he works primarily outdoors (unlike students, who live together in dormitories).

This patient’s age group and presentation strongly suggest pneumococcal disease. S pneumoniae is by far the most common cause of meningitis in adults older than 18 years (responsible for more than 70% of cases).² The clinical and subtle radiographic findings further suggest that his meningitis followed a bacteremic pneumonia—which is typical of pneumococcal meningitis.

Penicillin resistance among pneumococci is yet another issue to consider.^2,3 The incidence of resistance is increasing and varies widely by region.

In addition, a far higher case-fatality rate is seen in pneumococcal meningitis (about 20%) than in meningitis caused by other organisms. Pneumococcal meningitis thus remains a very dangerous and life-threatening disease in adults.

The most current epidemiologic review² reveals several interesting trends in bacterial meningitis, which include:

•A decreasing case rate for bacterial meningitis (by 31%); thus, choice A is not a true statement.

•An essentially unchanged rank order of causative organisms—S pneumoniae the most common overall and affecting persons older than 18 years; group B streptococci in neonates; Neisseria in pediatric age groups; Listeria in the elderly and immunocompromised patients; and sporadic Haemophilus across all age groups. Thus, choice B is correct here.

•An unchanged case-fatality rate, disturbing but true despite advances in adjuvant care and the presence of powerful antibiotics (thus, choice C is incorrect). Perhaps the more routine use of dexamethasone to prevent neurologic complications and the use of rifampin-containing regimens³ will result in improvements in the future.

Outcome of this case. Blood and CSF cultures both grew S pneumoniae. Empiric therapy with ceftriaxone and vancomycin was started, and the sensitivity testing confirmed that the causative organism was indeed sensitive to these agents. Dexamethasone was also added. The patient’s condition slowly improved, and he was discharged on day 11.