Neisseria meningitidis

Probiotic Nose Drops May Protect Against Meningitis

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Probiotic nose drops reduced the likelihood of students being colonized with the bacteria that cause meningitis, according to a study published online March 25 in Clinical Infectious Diseases.

The nose drops contained Neisseria lactamica, a non-disease-causing relative of the bacterium that causes meningitis, Neisseria meningitidis. Epidemiological studies had previously shown that people who carry N lactamica in their nose and throat are both less likely to be colonized with N meningitidis and less likely to contract meningitis than people who do not, possibly because colonization with one species prevents colonization with the other.
“Neisseria lactamica may therefore be a potential ‘bacterial medicine’ to suppress meningococcal outbreaks,” write Alice M. Deasy, MBBS, from the Department of Infection and Tropical Medicine, Sheffield Teaching Hospitals Foundation Trust, and colleagues. They note that the effect on N meningitidis colonization was stronger and happened more quickly than the effect seen in previous studies from meningococcal vaccine.

The study involved 310 students from two universities in Sheffield, United Kingdom. Each received either an inoculation of 104 colony-forming units of N lactamica or a sham inoculation. The investigators took samples of the students’ oropharyngeal bacteria at 2, 4, 8, 16, and 26 weeks after inoculation.

At baseline, a similar fraction of each group already carried N meningitidis: 24.2% of the treatment group and 22.4% of control patients. (Only a handful of participants in each group [1.9%; 95% confidence interval, 0.4% – 3.5%] carried N lactamica at baseline.) After inoculation, some, but not all, participants in the treatment group became colonized with N lactamica: 33.6% (95% confidence interval, 25.9% – 41.9%) 2 weeks after inoculation, rising to 41.0% (95% confidence interval, 33.0% – 49.3%) by 26 weeks.

Conversely, the proportion of students colonized with N meningitidis dropped after inoculation, going from 24.2% to 6.7% after 4 weeks, and then partially rebounding to 14.5% at 26 weeks. Colonization in the control group was not reduced.

The loss of N meningitidis was greater in the students who were colonized with N lactamica (P = .013), suggesting N lactamica competes with and displaces N meningitidis. These participants were also less likely to acquire new colonization with N meningitidis (P = .011). Of those who were colonized, 13.3% acquired N meningitidis within the 26-week study period compared with 29.2% of control patients and 28% of those who received the inoculation but were not colonized by the probiotic strain.
At the end of the study, all participants received another dose of N lactamica and were tested 2 weeks later. Those who had been in the treatment group were still able to be colonized by N lactamica, and those who had been in the control group showed a similar reduction in N meningitidis carriage as the treatment group had shown at the beginning of the study.

On the basis of these and previous results, including the ability of the treatment group to be recolonized with N lactamica, the investigators write that the protective effect is probably not a result of cross-protective antibodies; rather, “[t]he mechanism is either microbial competition within the nasopharynx, or innate immune responses that operate only in individuals actively carrying the commensal.”

The Long-Term Effects of Childhood Bacterial Meningitis.

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Adult survivors of childhood bacterial meningitis have lower educational achievement and a lower likelihood of economic self-sufficiency than matched healthy controls.

 

The short-term sequelae of childhood bacterial meningitis can include hearing loss, motor deficits, seizures, and cognitive impairment. But what about functioning in adult life? In a recent cohort study, investigators used national patient registries in Denmark to compare the educational achievement and economic self-sufficiency of individuals with meningococcal, pneumococcal, or Haemophilus influenzae meningitis diagnosed between 1977 and 2007, before age 12 years, with those of age- and sex-matched controls who had not had meningitis. To assess for family-related cofactors, the researchers also evaluated the siblings and parents of these two cohorts.

Survivors of pneumococcal or H. influenzae meningitis were less likely than matched controls to complete high school or to obtain higher education by age 35. They also were less likely to attain these goals than their siblings, who performed similarly to the siblings of controls. In contrast, although meningococcal meningitis survivors were less likely than controls to complete high school or to obtain higher education by age 35, these survivors had educational achievement comparable to that of their siblings, who had lower achievement than the siblings of controls. Educational achievement was lower among parents of meningococcal meningitis survivors than among parents of controls; achievement among pneumococcal and H. influenzae meningitis survivor parents was comparable to that among controls. By 2010, fewer survivors than controls were economically self-sufficient (–3.8%, –10.6%, and –4.3%, respectively, for meningococcal, pneumococcal, and H. influenzae meningitis).

Comment: This large, well-designed study confirms sustained intellectual and economic sequelae of childhood bacterial meningitis but also suggests different routes to these long-term effects. Intellectual and economic impairments are likely direct consequences of the severity of pneumococcal and H. influenzae meningitis. However, family factors appear to predominate in the poorer intellectual and economic achievements of meningococcal meningitis survivors.

 

Source: Journal Watch Infectious Diseases