MR. P, 86, was brought to the ED by his wife with an acute onset of confusion, fever, and chills. In the ED, he denied pain or shortness of breath. Mrs. P stated that her husband hadn't been recently exposed to anyone ill and had no recent medication changes; recent travel; or use of alcohol, tobacco, or illicit drugs. His health history included hypothyroidism and type 2 diabetes mellitus. He had no known medication allergies.

Mr. P's vital signs were: temporal temperature, 102.3[degrees] F (39[degrees] C); heart rate, 86, regular; respiratory rate, 20; SpO₂, 96% on room air; and BP, 159/83 mm Hg. No neurologic focal deficits, nuchal rigidity, or photophobia were noted. His evaluation included a quick Sequential (sepsis-related) Organ Failure Assessment (qSOFA) score, an assessment score for patients outside the ICU to help identify those with suspected infection who are at greater risk for a poor outcome. It uses three criteria, assigning one point for hypotension (systolic SBP of 100 mmHg or lower), tachypnea (22 breaths or more per minute), or altered mentation (Glasgow coma scale score less than 15).1 Mr. P's qSOFA score was 1.

The SOFA score, which is done in the ICU (see SOFA score), uses simple measurements of major organ function to calculate a severity score to predict mortality. The score is calculated 24 hours after admission to the ICU and every 48 hours thereafter in the ICU. The mean and the highest scores are most predictive of mortality. Scores that increase by about 30% are associated with a mortality of at least 50%. Mr. P's SOFA score was 2 (less than 10% mortality).2

Diagnostic studies

Mr. P's white blood cell count was elevated at 16.6 x 103 cells/mm3 (normal, 4.5 to 10.5 x 103 cells/mm3). His initial serum lactic acid level was 2.1 mmol/L (normal, less than 2 mmol/L), with a repeat of 1.3 mmol/L.

Additional lab findings, including serum electrolytes, were within normal limits. Blood cultures were positive for Haemophilus parainfluenzae.

Imaging studies were negative for an infection source. Computed tomography of the chest, abdomen, and pelvis were nondiagnostic. Magnetic resonance imaging of the brain revealed no mass or hemorrhage, and the ECG was normal. An echocardiogram for possible valve vegetation and endocarditis was negative.

A lumbar puncture was performed for cerebrospinal fluid (CSF) analysis, including Gram stain and culture. The CSF analysis results included: glucose, 86 mg/dL (normal, 40 to 70 mg/dL) and protein, 157 mg/dL (normal, 15 to 45 mg/dL). With bacterial meningitis, a CSF glucose concentration under 40 mg/dL is found in about 60% of patients; CSF protein concentrations are elevated in virtually all patients.3 A Gram stain should be obtained whenever there is suspicion of bacterial meningitis. It has the advantage of suggesting the bacterial etiology one day or more before culture results are available.

Mr. P's CSF Gram stain revealed no organisms and the culture had no bacterial growth. CSF culture is the gold standard for a bacterial meningitis diagnosis and is positive in 80% to 90% of patients with community-acquired bacterial meningitis if the CSF is obtained before the start of antimicrobial therapy.3

Management

Meningitis was suspected as the primary infection source, but Mr. P's CSF specimens were negative for bacterial growth. His blood cultures were positive for H. Parainfluenzae, so Mr. P was diagnosed with H. parainfluenzae and metabolic encephalopathy. Droplet precautions were initiated pending all final culture results, and an infectious diseases consultation was requested. Antibiotic therapy was targeted to Mr. P's blood culture and sensitivity results.

H. parainfluenzae is a Gram-negative coccobacillus that's part of the normal flora in the oral cavity and oropharynx.4,5 It's been responsible for respiratory tract infections, bacteremia, endocarditis, biliary tract infections, hepatic abscesses, and meningitis.6 This pathogen can also cause genital and urinary tract infections and arthritis.7 Depending on the geographical area, certain H. parainfluenzae infections such as meningitis may be reportable to the public health department. Some types of meningitis are not considered a "national notifiable condition;" in Pennsylvania, where Mr. P's case took place, all types of meningitis are reportable.8,9

This organism is an opportunistic pathogen with the ability to cause life-threatening infection in immunocompromised individuals.6 It has also been reported in individuals without risk factors.7 Standard precautions are used when caring for patients with this infection. Transmission-based (droplet) precautions may be indicated until a definitive diagnosis and organism can be identified.10

At discharge to a skilled nursing facility, Mr. P was alert and oriented. He was afebrile, with leukocytosis resolution and blood cultures without growth.

SOFA score2

The SOFA score is based upon the following measurements of organ function:

* Respiratory: ratio of arterial oxygen tension to fraction of inspired oxygen (PaO₂/FiO₂)

* Cardiovascular: amount of vasoactive medication necessary to prevent hypotension

* Hepatic: serum bilirubin level

* Coagulation: platelet concentration

* Neurologic: Glasgow Coma Scale score

* Renal: serum creatinine or urine output

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