An interventional study of Neisseria lactamica in Meningitis, Meningococcal, sponsored by University Hospital Southampton NHS Foundation Trust. Terminated at 1 site in United Kingdom. Open to participants aged 18 Years to 45 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-02-12.
Sponsored by University Hospital Southampton NHS Foundation Trust · Not applicable, Interventional, and Prevention
This study is part of a project that aims to develop a vaccine with N. lactamica that prevents meningitis. The investigators have previously given nose drops containing N. lactamica to over 340 volunteers, and shown that many of the volunteers (35-60%) become colonised without causing any illness or disease. In the future the investigators would like to modify N. lactamica so that it can carry vaccine molecules into the nose of children. To do this the investigators need to know more about the immune response generated against N. lactamica. Previously the investigators have shown that inoculation resulted in an immune (antibody) response in volunteers who were colonised. Taking an antibiotic called ciprofloxacin will treat N.lactamica in the nose and throat of the volunteers. The investigators need to know if the immune response to N. lactamica is the same when colonised volunteers are treated with the antibiotic after 4 days, is the same if the investigators treat volunteers after 14 days of carriage. This information will inform future studies.
N. lactamica (Nlac) has been shown to be safe to use in human challenge experiments. Even at a very low dose of 10,000 colony forming units (cfu) long lasting colonisation with Nlac is easily induced in 35-65% of volunteers. The investigators have previously showed that increasing the inoculum to 100,000 cfu increased the subsequent carriage of Nlac to 50%. In 80-90% of those volunteers successfully colonised, this is detectable by 1-2 weeks.
Data regarding earlier detection of colonisation is currently lacking.
Colonisation has a clear effect on the volunteers nasal mucosal microbiome, in that meningococcal acquisition is effectively inhibited in volunteers who carry the organism. Colonisation is immunogenic, with an increase in specific serum IgG by 2 weeks and specific salivary IgA by 4 weeks.
No antibiotic eradication therapy has previously been given following experimental inoculation but Ciprofloxacin has been shown to be effective in the eradication of N. meningitidis.
To design future planned studies using Nlac nasal inoculation and colonisation in order to prevent invasive N. meningitidis disease, it is necessary to further evaluate the colonisation kinetics and efficacy of the eradication following antibiotic treatment. In previous challenges the investigators inoculated volunteers with Nlac and followed those volunteers for prolonged periods of time (over 6 months).
This study will compare the effect of short (4 days) versus longer (14 days) periods of nasal carriage of Nlac in volunteers on immunogenicity, and confirm the efficacy of antibiotic eradication therapy with ciprofloxacin.
Healthy adult volunteers will receive a nasal inoculation of Nlac with an antibiotic given on day 4 or 14. This information will be used to inform the design of future research into the colonisation and immunogenicity of related organisms.
Before designing future protocols the study investigators need to know whether a short containment of the volunteers will be sufficient for immunogenicity, and how quickly the volunteers can be discharged after antibiotic treatment.
A wild-type strain of Nlac (Y92-100) will be used for this study, selected because the investigators have previously used it safely in experimental challenge of over 340 human volunteers.
The same strain will be the parent strain for any future GMO work.
113 studies on the registry are indexed under Meningitis, Meningococcal; 9 are open to participants now.
This study's enrollment of 21 is below the median of 552 across 103 interventional studies indexed under Meningitis, Meningococcal.
Browse Meningitis, Meningococcal studies →University Hospital Southampton NHS Foundation Trust is the lead sponsor of 147 studies on the registry; 36 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Nasal drops containing Neisseria lactamica are administered at Day 0 by the study doctor. Eradication therapy with the antibiotic Ciprofloxacin given on Day 4, unless required sooner. Follow up visits occur on Days 5, 14 and 32.
Biological: Neisseria lactamica
Nasal drops containing Neisseria lactamica are administered at Day 0 by the study doctor. Follow up visits on Day 4 and 7 to check for N. lactamica carriage. Eradication therapy with the antibiotic Ciprofloxacin given on Day 14, unless required sooner. Follow up visits occur on Days 15, 24 and 42.
Biological: Neisseria lactamica
Colonisation by bacteria is an immunising event; we proved this in humans by inoculating university students intranasally with the harmless commensal N. lactamica and we observed both specific systemic and mucosal antibody responses by 4 weeks. Experimental challenge with defined bacteria could tease out the Th17-mediated response mechanisms, which include waning of immunity over time, the induction of an incorrectly polarised T cell response, lack of cross-reactivity between strains or active immune evasion mechanisms employed by bacteria to subvert host immune effector mechanisms.
Measure the Antibodies, by Serological Antibody Titration, of Short Term Colonisation and Longer Colonisation
Measure any rise in serological specific antibodies from samples taken at the start of the study (Day 0) and samples taken on Day 14 post inoculation and Day 28 post antibiotic eradication (Group 1 = Day 32 or Group 2 = Day 42)
Time frame: Up to 42 Days
Measure the Colonisation of Neisseria Lactamica
Measure if Neisseria lactamica is able to colonise at or before Day 4 (for group 1) or Day 14 (for group 2) from cultured throat swabs.
Time frame: Up to 14 Days
Measure the Eradication of Neisseria Lactamica
Record how successful eradication is up to Day 42, using throat swab samples.
Time frame: Up to 42 Days
Healthy adult volunteers were recruited according to a REC approved recruitment strategy between 3/3/17 and 14/4/20. Participants attended a face to face screening visit at NIHR Southampton CRF to obtain informed consent and determine eligiblity
| Milestone | Group 1 | Group 2 |
|---|---|---|
| Started | 13 | 8 |
| Completed | 12 | 7 |
| Not completed | 1 | 1 |
| Withdrew: Withdrawal by subject | 1 | 1 |
Measure any rise in serological specific antibodies from samples taken at the start of the study (Day 0) and samples taken on Day 14 post inoculation and Day 28 post antibiotic eradication (Group 1 = Day 32 or Group 2 = Day 42)
| Titres of antigen specific IgG | Day 0 | Day 14 | Eradication + 28 |
|---|---|---|---|
| Nlac-IgG Group 1 | 5.3 (3.3 to 6.4) | 5.5 (3.9 to 6.6) | 5.6 (4.6 to 7.1) |
| Nlac-IgG Group 2 | 4.6 (3.2 to 9.5) | 13.4 (9.3 to 14.7) | 10.3 (7.7 to 13.1) |
| Nmen-IgG Group 1 | 22.6 (20.4 to 26.1) | 23.7 (18.5 to 27.8) | 23.2 (19.4 to 26.6) |
| Nmen-IgG Group 2 | 10.4 (8.0 to 13.9) | 17.3 (9.5 to 33.6) | 14.5 (9.5 to 22.3) |
Measure if Neisseria lactamica is able to colonise at or before Day 4 (for group 1) or Day 14 (for group 2) from cultured throat swabs.
| Participants | Group 1 | Group 2 |
|---|---|---|
| Measure the Colonisation of Neisseria Lactamica | 7 | 6 |
Record how successful eradication is up to Day 42, using throat swab samples.
| Participants | Group 1 | Group 2 |
|---|---|---|
| Measure the Eradication of Neisseria Lactamica | 6 | 4 |
Collected over From enrolment until the end of follow up - 32 days post inoculation for Group 1 and 42 days post inoculation for Group 2. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Group 1 | 0/13 (0%) | 0/13 (0%) | 3/13 (23.1%) |
| Group 2 | 0/8 (0%) | 0/8 (0%) | 6/8 (75%) |
| Event | Group 1 | Group 2 |
|---|---|---|
| Respiratory tract symptomsRespiratory, thoracic and mediastinal disorders | 3/13 | 2/8 |
| Malaise / lethargy / headacheGeneral disorders | 0/13 | 2/8 |
| Diarrhoea / vomitingGastrointestinal disorders | 0/13 | 1/8 |
| Dysuria / cystitisRenal and urinary disorders | 0/13 | 1/8 |
| Age, Continuous(Years) | Group 1 | Group 2 | Total |
|---|---|---|---|
| Median | 33 (25 to 45) | 29 (25 to 39) | 31 (25 to 45) |
| Sex: Female, Male(Participants) | Group 1 | Group 2 | Total |
|---|---|---|---|
| Female | 8 | 8 | 16 |
| Male | 5 | 0 | 5 |
| Race and Ethnicity Not Collected(Participants) | Group 1 | Group 2 | Total |
|---|---|---|---|
| Count of participants | — | — | 0 |
| Specific IgG titres(Antibody titre) | Group 1 | Group 2 | Total |
|---|---|---|---|
| Nlac-specific IgG titre | 5.3 (3.3 to 6.4) | 4.6 (3.2 to 9.5) | 5.0 (3.0 to 7.5) |
| Nmen-specific IgG titre | 22.6 (20.4 to 26.1) | 10.4 (8.0 to 13.9) | 17.1 (10.8 to 23.8) |
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University Hospital Southampton NHS Foundation Trust