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Meningitis patients twice as likely to have taken antimicrobials, say researchers

Patients with meningitis are twice as likely as to have taken antimicrobials within the year before diagnosis that those without the disease, claim researchers.

A team from King's College, London also found that patients with meningitis were four times more likely than those without a diagnosis of meningitis to have taken antimicrobials in the week preceding diagnosis, while patients who had been prescribed more than four antimicrobial prescriptions in the previous year were almost three times more likely to contract meningitis than controls.

The researchers concluded that the study provided 'another reason for caution in antimicrobial prescribing in general practice'.

It comes at a time when GPs are under increasing pressure to reduce antimicrobial prescribing because pathogens are showing an increasing resistance to commonly prescribed drugs.

The study, published in the British Journal of General Practice, took data from 685 general practices and compared antimicrobial prescription in over 7,000 bacterial and viral meningitis cases with nearly 30,000 controls.

The team considered that antimicrobials may disrupt the body’s natural microbiome to facilitate meningitis, but this was not fully supported by the study and the researchers suggest that the results may reflect that patients requiring more antimicrobials are more susceptible to infection.

In spite of this, the team believe that their research is important and provides evidence that antimicrobial overprescribing may be associated with an increased risk of both bacterial and viral meningitis.

Concluding in the paper, the team write: ‘While the exact mechanism for the association between the antimicrobial prescription and subsequent meningitis cannot be determined by the case-control design used in this study, the size of that association merits further investigation.

‘It also adds another reason for caution in antimicrobial prescribing in general practice to the existing concerns about antimicrobial resistance.’


Readers' comments (2)

  • So which is the cause and which is the effect? I would have thought it far more likely that those ill enough to need previous antimicrobials are demonstrating a reduced immunological response to infection, rather than that it's anything to do with previous prescriptions for antimicrobials

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  • This does not surpise me.

    We know that oranisms such as the meningogoccus exhibit "competitive inhibition". In other words, if your nasopharynx is colonised with a (harmless) Neisseria organism, this will make it harder for a new, potentially pathogenic to establish itself in that ecological niche.

    We know that if you're going to get ill with a particular strain of meningococcus, you get ill within 5 days. (OK, people sometimes, though rarely, get ill within 7 days; and one case has been reported where the exposure seems to have been more than 7 days previously; but in practical terms it's within 5 days...) If you survive 5 days after exposure without getting ill, you're very unlikely to do so.

    The purpose of chemoprophylaxis (antimcrobials to eliminate meningococci) for meningococcal disease is to eliminate the hypothetically more virulent strain from the person the case acquired it from.

    I've always explained that if you give somebody chemoprophylaxis to people who are NOT in the fairly close group of people we identify as contacts, you could be increasing their risk by eliminating the harmless Neisseria organisms that are present in their nasopharynx, providing a degree of protection via competitive inhibition.

    This study supports the advice I have long given!

    It also makes me question (again) the advice about chemoprophylaxis. If antimicrobials increase the risk of meningococcal disease in the general population, what do they do in close contacts of cases?

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