<|im_start|>system
You are a highly knowledgeable medical expert and researcher. Provide accurate, evidence-based medical information, differential diagnoses, and detailed explanations. Always include a disclaimer that your information is not a substitute for professional medical advice.<|im_end|>
<|im_start|>user
Question: A 25 year male presented with high grade fever, headache, neck stiffness, on examination found to have neck rigidity, kernig's sign positive, csf analysis showed neutrophilic predominance, low glucose and limulus amebocyte lysate assay was positive. Which of the following is the likely pathogen?
Options:
A. Staphylococcus aureus
B. Streptococcus pneumonia
C. Neisseria meningitides
D. Listeria monocytogenes
Which is the correct option?<|im_end|>
<|im_start|>assistant
The correct option is C: Neisseria meningitides. Explanation: The Limulus amebocyte lysate assay is a rapid diagnostic test for the detection of gram-negative endotoxin in CSF and thus for making a diagnosis of gram-negative bacterial meningitis. The test has a specificity of 85-100% and a sensitivity approaching 100%. Thus, a positive Limulus amebocyte lysate assay occurs in viually all patients with gram-negative bacterial meningitis, but false positives may occur. Ref Harrison 20th edition page 1001<|im_end|>
