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N. lactamica may suppress meningococcal outbreaks
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Nasal inoculation with live Neisseria lactamica inhibited meningococcal carriage in young adults, according to results of a block-randomized human challenge study.
“Neisseria lactamica may therefore be a potential ‘bacterial medicine’ to suppress meningococcal outbreaks,” Alice M. Deasy, MBBS, of the Department of Infection and Tropical Medicine, Sheffield Teaching Hospitals Foundation Trust, and colleagues wrote in Clinical Infectious Diseases.
The researchers enrolled 310 healthy students from two universities in Sheffield, United Kingdom, between October and December 2011. They inoculated a challenge group of 149 students with intranasal 104 colony-forming units of N. lactamica. A control group of 161 students received a sham inoculation.
Deasy and colleagues took oropharyngeal swabs before inoculation and at 2, 4, 8, 16 and 26 weeks. At baseline, carriage rates for Neisseria meningitidis were similar for both groups: 22.4% in the control group and 24.2% in the challenge group. Within 2 weeks of inoculation, 33.6% of the challenge group was colonized with N. lactamica. By week 26, 41% of the challenge group had been colonized with N. lactamica at some point during the study.
Two weeks after inoculation, colonization with N. meningitidis increased to 23.6% in the control group. In the challenge group, however, meningococcal carriage dropped to 14.7% (P = .006). This meningococcal inhibition, sustained over 16 months, was limited to those participants who were carriers of N. lactamica. The researchers attributed the reduction in carriage rates to the displacement of existing N. meningitidis and to the inhibition of its new acquisition.
“Herd protection by carriage reduction is a major effector of current meningococcal vaccines,” Deasy and colleagues wrote. “The current study reveals a potent effect of inoculated live N. lactamica on carriage and acquisition of the pathogen N. meningitidis.” – by Colleen Owens
Disclosure: The researchers report no relevant financial disclosures.
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