A 44-year-old man is brought to the emergency department by his wife because of confusion that began a few hours ago. Earlier in the day, he complained of a severe headache and nausea. On physical examination, his temperature is 38.3 C (101 F) and nuchal rigidity is present. Lumbar puncture and cerebrospinal fluid (CSF) examination show: Gram stain of the CSF would most likely reveal which of the following?

Question

A 44-year-old man is brought to the emergency department by his wife because of confusion that began a few hours ago.  Earlier in the day, he complained of a severe headache and nausea.  On physical examination, his temperature is 38.3 C (101 F) and nuchal rigidity is present.  Lumbar puncture and cerebrospinal fluid (CSF) examination show:  Gram stain of the CSF would most likely reveal which of the following?

Quizplus · Accepted Answer

A patient presenting with confusion, headache, fever, and nuchal rigidity should immediately raise suspicion for meningitis. In bacterial meningitis, cerebrospinal fluid (CSF) analysis typically shows elevated opening pressure, increased neutrophils, decreased glucose, and elevated protein. The morphology of any observed bacteria on CSF Gram stain provides an excellent preliminary identification of the pathogen (whereas cultures take time to grow). Streptococcus pneumoniae is the most common cause of bacterial meningitis in adults of all ages (see reference). On CSF Gram stain, lancet-shaped Gram-positive cocci are found in pairs. S pneumoniae meningitis often follows a pulmonary infection or mild upper respiratory infection. Patients with alcohol use disorder, sickle cell anemia, asplenic individuals, and those in generally poor health are at greater risk for S pneumoniae meningitis. (Choice A) Bean-shaped Gram-negative cocci in pairs indicate Neisseria meningitidis. N meningitidis is the second most common cause of meningitis in patients < 60 years of age. N meningitidis tends to occur in outbreaks where many individuals live in close quarters (eg, army barracks and college dormitories). (Choice C) Gram-positive cocci in clusters indicate Staphylococcus species. Staphylococcus is an unusual cause of community-acquired meningitis but is common in neurosurgical patients. It is thought that bacteria gain access to the meninges by direct inoculation during the procedure or postoperatively through the wound. (Choice D) Haemophilus influenzae is a Gram-negative coccobacillus. H influenzae infection is becoming less common now that vaccination with the Hib capsule vaccine, a protein-capsule polysaccharide conjugate vaccine, has become widespread. (Choice E) Listeria monocytogenes is a facultatively intracellular, motile, Gram-positive rod. It is the third most common cause of meningitis in neonates, after group B Streptococci and Escherichia coli. Listeria also causes meningitis in immunosuppressed patients and the elderly. Educational objective: Bacterial meningitis causes an increase in cerebrospinal fluid (CSF) neutrophil count and protein concentration as well as a decrease in CSF glucose. Streptococcus pneumoniae is a leading cause of community-acquired pneumonia, otitis media, and meningitis in adults. S pneumoniae appears on Gram stain as lancet-shaped, Gram-positive cocci in pairs. __________ References: Bacterial meningitis in the United States, 1998-2007. (http://www.ncbi.nlm.nih.gov/pubmed/21612470)

A 44-Year-Old Man Is Brought to the Emergency Department by His