Cerebrospinal fluid (CSF): Chemical, cytological and culture analysis

Summary

The study of cerebrospinal fluid (CSF) plays a crucial role in diagnosing meningitis and encephalitis, both infections of the central nervous system. CSF analysis involves physical, chemical, cytological, and microbiological tests to identify the underlying cause, whether bacterial, viral, or fungal. Common pathogens include *Neisseria meningitidis*, *Streptococcus pneumoniae*, and *Cryptococcus neoformans*. Modern diagnostic tools, like multiplex PCR, offer rapid results, aiding in timely diagnosis. The video outlines the procedures for CSF collection, the types of meningitis, and diagnostic methods used to differentiate between bacterial, viral, and fungal etiologies.

Takeaways

• 😀 Cerebrospinal fluid (CSF) analysis is crucial for diagnosing suspected meningitis and encephalitis, which are infections of the central nervous system.
• 😀 Common symptoms of meningitis and encephalitis include fever, vomiting, neck stiffness, altered consciousness, and coma, with signs like Kernig and Brudzinski indicating meningitis.
• 😀 CSF is collected through a lumbar puncture, typically between the L3-L4 or L4-L5 intervertebral spaces, in a sterile environment.
• 😀 When collecting CSF, it is recommended to gather at least three tubes for clinical chemistry, microbiology, and cell counts, though two or even one can be used in some cases.
• 😀 The bacterial agents most commonly responsible for meningitis and encephalitis include *Neisseria meningitidis*, *Streptococcus pneumoniae*, and *Haemophilus influenzae*.
• 😀 Other agents, such as *E. coli*, *Listeria monocytogenes*, and *Group B Streptococcus*, are more common in neonates, while viruses like enterovirus, herpes simplex, and HIV also contribute to infections.
• 😀 Tuberculous meningitis and fungal infections like *Cryptococcus neoformans* are also considered when diagnosing infections, especially in patients with compromised immune systems, such as those with HIV.
• 😀 CSF analysis involves physical examination (checking for turbidity or xanthochromia), chemical tests (glucose and protein levels), and cytological tests (cell counts and differential analysis).
• 😀 A low glucose level, high protein levels, and a predominance of polymorphonuclear cells typically indicate bacterial meningitis, while viral meningitis presents with normal glucose and only mildly elevated protein levels.
• 😀 Microbial cultures and PCR methods like FilmArray are used for pathogen identification, with FilmArray offering a quick, multiplex test for bacteria, viruses, and fungi in a single sample, providing results on the same day.

Q & A

What is the main focus of this video on cerebrospinal fluid?

The video primarily focuses on the study of cerebrospinal fluid in the context of suspected meningitis and encephalitis, which are infections affecting the central nervous system.

What are the common symptoms of meningitis and encephalitis?

Common symptoms include fever, vomiting, neck stiffness, altered consciousness, and even coma. The Kernig and Brudzinski signs may also appear, indicating irritation of the meninges.

How is cerebrospinal fluid collected for analysis?

Cerebrospinal fluid is collected through a lumbar puncture, typically at the L3-L4 or L4-L5 intervertebral space, under sterile conditions in an operating room.

What types of tests are performed on cerebrospinal fluid to determine the cause of meningitis or encephalitis?

The cerebrospinal fluid is subjected to cytological, cytochemical, microbiological tests, and sometimes cultures, to help identify the cause of the infection.

What are the most common bacterial agents responsible for meningitis and encephalitis?

The most common bacterial agents include Neisseria meningitidis (meningococcus), Streptococcus pneumoniae (pneumococcus), and Haemophilus influenzae, with E. coli, Listeria monocytogenes, and group B Streptococcus being significant in neonatal populations.

What viral agents are associated with meningitis and encephalitis?

Viral agents include enterovirus, herpes simplex virus, varicella zoster virus, and HIV. These are more commonly associated with viral meningitis and encephalitis.

How is tuberculosis-related meningitis different from other bacterial forms?

Tuberculous meningitis typically has a more subtle presentation, with less marked leukocytosis, a predominance of mononuclear cells, and moderately elevated proteins in the cerebrospinal fluid.

What is the normal appearance of cerebrospinal fluid, and what does turbidity indicate?

Normal cerebrospinal fluid is clear and transparent, resembling rock water. Any turbidity or discoloration, such as pink, yellow, or orange tones (xanthochromia), is considered pathological.

How is the chemical analysis of cerebrospinal fluid conducted?

The chemical analysis focuses on glucose and protein levels. Glucose should be about 60% of the blood glucose level, and protein levels should normally be less than 45 mg/dL in cerebrospinal fluid.

What role does the cytological analysis of cerebrospinal fluid play in diagnosis?

The cytological analysis involves counting cells in the cerebrospinal fluid. A normal count should not exceed five leukocytes per microliter, with a predominance of mononuclear cells. The analysis helps differentiate between bacterial, viral, and fungal infections.