What is the suggested prophylaxis and recommended mask use for individuals exposed to Neisseria Meningitidis (NM) in a college laboratory setting, where the bacteria were handled in petri dishes and may have aerosolized, with exposures occurring 6 days ago and today?

Prophylaxis and Mask Use for Laboratory Exposure to Neisseria Meningitidis

All individuals exposed to potentially aerosolized Neisseria meningitidis in the laboratory setting should receive antibiotic prophylaxis with either ciprofloxacin (single 500 mg oral dose), rifampin (600 mg twice daily for 2 days), or ceftriaxone (250 mg IM single dose) as soon as possible, regardless of whether the exposure occurred today or 6 days ago. 1

Antibiotic Prophylaxis

Recommended Prophylactic Regimens

• Ciprofloxacin: 500 mg orally as a single dose (for adults >16 years) 1
• Rifampin: 600 mg orally twice daily for 2 days (for adults) 1, 2
• Ceftriaxone: 250 mg intramuscularly as a single dose (for adults) 1

Timing of Prophylaxis

• Prophylaxis should be administered as soon as possible after exposure 3
• Prophylaxis is still recommended for those exposed 6 days ago, as it can be effective when administered within 14 days of exposure 1, 3
• Prophylaxis administered more than 14 days after exposure has limited or no value 1, 3

Selection of Antibiotic

• In areas without known ciprofloxacin resistance, any of the three recommended antibiotics can be used 1
• In areas with documented ciprofloxacin resistance, rifampin or ceftriaxone should be preferred 4
• Ceftriaxone is the preferred option during pregnancy 1

Mask Use Recommendations

• Droplet precautions should be implemented for all exposed individuals until they have received 24 hours of effective antibiotic prophylaxis 1
• Surgical masks should be worn by exposed individuals when in close contact (<3 feet) with others 1
• Laboratory workers should continue to wear masks when handling any potentially infectious materials 1

Risk Assessment

• Laboratory exposures to N. meningitidis, particularly when aerosolization may have occurred, represent a significant risk 1, 3
• Clinical microbiologists and research microbiologists routinely exposed to N. meningitidis isolates are at increased risk and should receive prophylaxis after exposure 1
• The risk of meningococcal disease is estimated to be 25 times greater for exposed healthcare workers than for the general population 1, 3

Monitoring After Prophylaxis

• All exposed individuals should be monitored for symptoms of meningococcal disease (fever, headache, stiff neck, nausea, vomiting, photophobia, altered mental status, petechial or purpuric rash) for at least 10 days after exposure 3
• If symptoms develop despite prophylaxis, immediate medical attention should be sought 1

Special Considerations

• Rifampin may lead to development of resistant isolates if used extensively during an outbreak 5
• Rifampin can turn body fluids (including urine, tears, and saliva) orange-red and can permanently discolor soft contact lenses 2
• Ciprofloxacin is contraindicated in pregnancy 1
• For individuals with known asplenia, complement deficiencies, or HIV infection, consideration should be given to meningococcal vaccination in addition to antibiotic prophylaxis 1

Laboratory exposures to N. meningitidis require prompt intervention with appropriate antibiotic prophylaxis to prevent potentially fatal meningococcal disease. The effectiveness of prophylaxis decreases with time, so immediate action is essential even for exposures that occurred several days ago.