ID 1 Tuberculosis, Dr Mike Brown
Speaker key
MB Mike Brown
IV Interviewer
MB So my name’s Mike Brown. I’m a consultant physician at the Hospital for Tropical Diseases which is the core of the infection service at UCLH and my talk today was about tuberculosis – why it’s in the news at the moment and what it means for you in primary care to make the diagnosis earlier to refer the patients up to our service, what we can do for the patients there.
IV What is the prevalence of TB in London?
MB So, London has the reputation of being the TB capital of Europe. There’re more cases of TB in London than in any other capital city in Europe. It is a problem here and rates have been high for a long time. The good news is that in the last few years rates have started declining. This probably relates to changes in migration, but also the recent introduction of a pre-entry screening x-ray for anyone coming to live here who needs a visa from a high prevalence country for TB.
IV Which groups or populations have a high rate of TB infection?
MB So, as I’m sure you know, TB occurs in London predominantly in people who have been born or spent many years in countries where there’s a lot more TB, so the typical patient with TB will have been born in South Asia or Southern Africa; they move to the UK well, and often two, three, four, five years later they then progress to developing active TB.
These represent about 75% of the patients in London who are diagnosed with TB but other groups who are at risk are people with HIV, people living in poor, difficult settings like homeless shelters, hostels, prisons; those are other groups as well. There are cases seen in people who’ve not been exposed anywhere other than in the straight streets of London. Those are much less common but they do represent often the patients who end up in the media but certainly a proportion of the patients we see in our clinic.
IV Why is it important to recognise and diagnose TB?
MB So, TB is a chronic illness that can cause a lot of chronic problems. The main thing for the patient as an individual is that it can cause lung destruction, which if untreated, can cause problems later on but as you know that 50% of cases of TB in London are not pulmonary TB, they are extra-pulmonary TB and we do see patients presenting frequently to us who’ve got TB of the spine or TB of the brain and those can have really long-term neurological deficits.
We still do see patients in London dying of TB, a condition which, if identified early, is entirely treatable and those deaths are preventable so early recognition and awareness about TB in primary care does translate into more rapid diagnosis, and more rapid diagnosis also means less transmission of TB to other people which is obviously benefit to the London population.
IV When should GPs think about TB?
MB So, pulmonary TB is perhaps quite straightforward but extra-pulmonary TB, typically TB in the spine or the lymph nodes or the abdomen can be a little bit more difficult to spot among the non-specific symptoms that many patients will present to you with, and what I tend to say to try and encourage in junior doctors and also in GPs is to try and remember about the importance of learning a patient’s country of birth because if we know that someone has lived at some point in their life in a country of high prevalence TB then even five, ten, fifteen years later, the cause of their symptoms now may be TB, and if you think about and record and use that information, that’s one of the best ways to help think could this be TB that’s the cause of my patient’s chronic thoracic back pain and weight loss.
IV What tests would a GP do if they suspect TB?
MB So, pulmonary tuberculosis is best diagnosed by microscopy of a sputum sample, and certainly when we suspect pulmonary tuberculosis in the TB clinic, that’s the sample that we'll send to the lab and we will make sure it gets processed appropriately to diagnose TB. I don’t think that a sputum sample is the best test for you to use in primary care because there are many patients with pulmonary tuberculosis who may well have negative sputum microscopy or be unable to expectorate. My feeling is that if you suspect TB in a patient either because of a chronic cough with haemoptysis or a chronic cough and they originate from a high prevalence country, then ask for a chest x-ray because the radiologist will spot the features that are suggested of TB and will then put a report that will prompt you to refer the patient on to us.
If you wish to do the sputum test in primary care that’s fine but I think it’s important to have the proviso that of course extra-pulmonary TB won’t present in the sputum and that index of suspicion has to remain high for the patient who has a chronic cough. We’re very happy in our walk-in clinic at the North Central London South Hub Clinic, to see patients in the walk-in service, organise the appropriate test there, and if you suspect TB and you want to send the patient straight up to us for sputums, for chest x-rays we’re happy to see them and take things from there, and refer them back to you straight away if TB’s not the diagnosis.
IV Where should a GP refer to?
MB So, around a third of the patients, perhaps more, that we manage in our TB clinic start their journey as a hospital patient and our inpatient unit at University College Hospital on our infectious diseases ward where we have negative pressure rooms to look after those most infectious patients. There will always be patients who are sick enough when they first present that the best place for them to go first for is to A&E and to phone us on the infectious diseases team to tell us the patient’s arriving so we can get them into the appropriate ward and the appropriate treatment.
The patient who’s less unwell we would recommend that you refer them directly to our TB clinic, and our North Central London South Hub TB Clinic, which is part of a network of North Central London clinics for TB is based at the Whittington Hospital. We have a dedicated new clinic there. We’re very proud of it. It has a walk-in clinic, open access on Mondays and Fridays and we have consultant run clinics on all the other days of the week.
IV How common is drug-resistant TB?
MB So, nowadays drug-resistant TB in London is a problem. Rates of isoniazid- resistant TB are round about 6-7% and there’s been an on-going outbreak of isoniazid-resistant TB that’s been responsible for more than 200 cases been going on for the last 15 or 20 years. It’s not that difficult to manage and patients, it doesn’t generally result in more complicated disease. We’re very careful to support those patients through to a completion of what may turn out to be a longer than six month course of treatment.
Multi-drug-resistant TB is another kettle of fish. Only responsible for 1, maybe 2% of cases of TB in London but it’s a real issue because it’s so much more difficult to treat and the risks of transmission are a real problem. It’s associated with more toxicity of the drugs, patients end up needing to stay in hospital for a very long time.
But we have new tools now that help us make a diagnosis of drug-resistant TB, and make it quickly. The GeneXpert PCR test is a test that we can do on a sputum sample, and within two hours of making a diagnosis of TB in a sputum sample, we’ve also established whether the patient has multi-drug-resistant TB, and that means we can get the patient into the right room and onto the right therapy early rather than months later when the results come back from the laboratory to tell us the sensitivities, or even later when they fail conventional treatment so we do quite a lot of work now when the patient’s first diagnosed with TB, to answer the question is this drug- sensitive TB which can usually be managed straight away at home, or is this drug-resistant TB, which may well need a long period of time in hospital on more complex newer drugs.
IV Have there been any new developments in the last five years for diagnosis or treatment?
MB So far, no. At the moment we only have the conventional six-month regimen for treating TB. I think that in another five years’ time there’ll be a lot of new regimens coming through the clinic, which will allow us to either identify some people who can have much shorter treatment or give everybody perhaps three, four months of treatment for their tuberculosis.
At the moment perhaps one of the biggest focuses for London is about trying to recognise and treat latent TB infection rather than waiting until the patient has developed active TB. We know that diagnosing active TB is often, as I’ve explained, related with delays in diagnosis and we want to identify cases before they become infectious.
One relatively new test which we’re using increasingly in secondary care and will be coming your way in primary care is the Interferon-Gamma Release Assay, for example, the quantiferon test which allows us to make an accurate diagnosis of latent TB infection without the phaff of having to have a tuberculin skin test, come back two days later for it to be read, etc, etc, and by identifying with a straightforward blood test, patients with latent TB infection, it will identify people who would potentially benefit from chemoprophylaxis from treatment of latent TB infection using a short three-month regimen of rifampicin and isoniazid.
What’s going to happen across London – it’s already in place in Northeast London and it will be coming through in the next year or so in North Central London – is screening for latent TB infection in primary care, using quantiferon test as part of the new entrant registration screening in patients newly registering in primary care.
IV Where can GPs find out more?
MB So, there’s information about our local TB services on the Camden CCG website. You can also go straight to our clinic website which is tbnorthcentrallondon.nhs.uk. If you want to email the TB service directly, , you can email me on . If you have an urgent referral, either through the TB clinic or if you think the patient needs admission to hospital, contact our infectious diseases registrar on 07908 250924 and we'll advise and see accordingly.
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