Turbid CSF with Gram-Negative Diplococci in a Rural Laboratory
A 5-year-old boy is brought to a rural hospital with fever of 39.5°C, neck stiffness and a petechial rash. A lumbar puncture is performed at 2 am. The laboratory receives a turbid CSF sample in a plain sterile container without transport medium. Cell count is 4,500 white cells/µL with 90% neutrophils; protein is 180 mg/dL; CSF glucose is 28 mg/dL while blood glucose is 96 mg/dL. Gram stain shows many gram-negative diplococci, some inside neutrophils. The laboratory has chocolate agar, blood agar and MacConkey agar, but the only CO2 incubator is occupied by a 48-hour mycobacterial culture. There is a candle jar and a jar with a gas-generating sachet that expired two months ago. No latex agglutination kit or molecular test is available. The clinician telephones for a preliminary report at 2:45 am and asks whether to start meningococcal prophylaxis for contacts.
1. Interpret the CSF findings and Gram stain. What preliminary report should be issued and how should it be communicated?
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The CSF shows a marked neutrophilic pleocytosis (4,500 white cells/µL, 90% neutrophils), high protein (180 mg/dL) and low glucose (28 mg/dL; CSF-to-blood ratio 28/96 = 0.29). This pattern is consistent with bacterial meningitis. The Gram stain showing many gram-negative diplococci, including intracellular forms, strongly suggests Neisseria meningitidis until proven otherwise.
The preliminary report should be telephoned immediately as a critical result. State exactly what is seen: 'Gram stain of CSF shows numerous gram-negative diplococci, some intracellular; culture pending.' Avoid over-calling the species before culture or molecular confirmation, but do not delay the report. Record the time, the person who received the report and a read-back. Advise the clinician that the findings are consistent with meningococcal meningitis and that infection-control advice should be sought immediately. A preliminary Gram stain is clinically actionable and should not wait for culture.
2. How should the culture be set up with the resources available? Include media, atmosphere and handling if the CO2 incubator is occupied.
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Process the CSF immediately; do not refrigerate it. Centrifuge if volume permits and use the deposit for culture and a repeat Gram stain. Inoculate chocolate agar and blood agar; MacConkey agar can be included to assess other gram-negative organisms. Use a sterile loop and spread the sample over the plate. Neisseria species require a humid, 5% CO2 atmosphere at 35-37°C. If the CO2 incubator is occupied by the mycobacterial culture, use a candle jar as a temporary alternative: place the plates in the jar, light a candle, seal and incubate. Do not use the expired gas-generating sachet as the sole method because its CO2 output cannot be trusted. Label the plates urgently and examine them after 18-24 hours, with a Gram stain and subculture of any growth. If the candle jar is also unavailable, incubate the chocolate agar in the ordinary incubator and subculture promptly, but recognise that growth may be poorer.
3. What follow-up, public health and quality actions are needed after the preliminary report?
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Inform the clinician and infection-control team immediately so that droplet precautions and appropriate therapy can be started. Meningococcal disease is notifiable; the local public health authority should be contacted to arrange chemoprophylaxis for close contacts, including household members and anyone exposed to the patient's oral secretions. The clinician asked about prophylaxis because this is a public-health decision, not a laboratory decision alone; the laboratory should provide the confirmed organism identification as soon as possible.
Quality actions: review why the CSF was sent without transport medium and why the CO2 incubator was unavailable; check the critical-result policy and read-back documentation; ensure an alternative CO2 system is available; and audit the turn-around time. Laboratory staff who handled the sample without appropriate precautions should be assessed under occupational-health advice. Culture identification, susceptibility testing and, if available, molecular confirmation should follow, and the final report should correct or confirm the preliminary Gram-stain interpretation.