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Comissioning of a new TB unit - Canada.

By Adrian Sebastian | 18 Oct, 2018

Hello colleagues,

I was recently asked about "certification" for a new TB unit/ward in Canada. We do have ventilation standards through our Canadian Standards Association (CSA).
I know that this type of work is quite niche... Is there anyone that can point me to any guidelines/checklists that is used for commissioning TB units in a developed countries?

Thanks in advance...

Replies

 

Edward Nardell, MD Moderator Replied at 12:00 PM, 18 Oct 2018

Two comments.
1) If there are guidelines, such as 12 ACH, then any commissioning service
can test the systems to see if they meet those requirements. There is
nothing TB specific about building ventilation, negative pressure, etc, for
a TB ward. In terms of layout, procedures, etc - another matter, but
unaware of a specific checklist re. a TB ward.
2) I cannot but point out the irony. TB wards are the last place to expect
TB transmission regardless of ventilation, negative pressure, etc - except
for cases expected NOT to respond to treatment, that is, where effective
treatment is not possible. Even there, exposure is likely to be limited.
OK, early on, maybe the first 48 hrs, reasonable precautions are a good
idea, but if drug susceptibility is known and the patient is on a regimen
reasonably expected to be effective, transmission should stop almost
immediately based on Riley's and our studies in the human to guinea pig
transmission model.

Dick Menzies and colleagues in Canada showed years ago that HCW TST
conversions were more likely to occur on general medical wards rather than
associated with isolation rooms, etc. The biggest factor is unsuspected TB
or drug resistance, and secondarily, ventilation outside of isolation rooms
is more likely to be inadequate to prevent airborne transmission.

I am not suggesting that TB units not follow standards and be
commissioned. I just point out that we put all our TBIC efforts in exactly
the wrong place - TB wards - rather than promptly identifying unsuspected
infectious patients and unsuspected drug resistance outside of TB units and
get them on effective therapy. This approach we call FAST - Find cases
Actively, Separate and Treat effectively.

Ed

Joven Jebio Ongole Replied at 1:01 PM, 18 Oct 2018

Thanks Edward for this opinion on TBIC. You are completely right if high
disease burden settings, found in most developing countries, like in
Africa. This will not be the case in low Tb disease setting like in Canada
and an extra measures will have to be taken to protect non-immune staff
from past exposure and primary disease

Jacqueline Gautier Replied at 6:18 AM, 19 Oct 2018

Thank you very much Dr Nardell.
I will use your words to reiterate these messages to the staff of my hospital.
They are always trying to have our direction to do more where we already know the risks and do take precautions while belittling the risks brought by TB cases not known yet and therefore going around and spreading the Mtb. ( les cracheurs de BK as we say in French)

Tamirirashe Mahwire Replied at 6:49 AM, 19 Oct 2018

Dr Ongole are you suggesting that prior exposure to TB confers immunity to
Active TB. If so please share the literature. I think Edward is
emphasising the need for early diagnosis and appropriate treatment in non
TB wards. A patient maybe coughing in a medical or maternity ward for a
week. The maternity ward will not have TB infection control mechanismsin
place. Staff will not use N95. After eventual diagnosis if delayed then pt
will be transferred to a TB unit . This pt if on appropriate treatment
will have sterilisation of their sputum after 48hrs as alluded by Edward.
Therefore while it is important to have first world TB infection control
standards in a TB ward. We need infection control protocol and standards in
all wards and departments. Early identification and appropriate treatment
of infectious cases is a fundamental principle of infection control.

Dr T.C Mahwire. HIV Clinician. Clinical Epidemiologist . Researcher

Edward Nardell, MD Moderator Replied at 9:20 AM, 19 Oct 2018

Thank you Dr. Mahwire, you re-stated the case well!

The original contributor indicated that active case finding is important
primarily in high-burden settings, which is true to the degree that most
chronic cough in low burden settings is NOT likely to be TB, even though
it should be considered. The problem in low burden settings is that TB is
not considered. I can relate case after case of TB in (usually)
foreign-born persons that is missed for months or years despite symptoms
because TB is not considered. I say foreign-born because that risk group
now accounts for more than 80% of TB cases in most US regions - although
anyone can acquire TB. At my hospital in Boston we treat many
immunosuppressed cancer patients and also patients receiving TNF alpha
inhibitors. Respiratory infections are common and TB should be suspected
despite low prevalence in the US. I have tried without success, for
example, to have upper room UV air disinfection installed in our
bronchoscopy suite - for the rare patient with unsuspected TB. It is these
cases that are likely to transmit, not the known TB patients started on
therapy in hospital. By the way, the effect of effective treatment on
transmission acts well before (hours, days) clearance of Mtb organisms
(months). This is true of first line treatment, probably due to INH and
Rif, and also MDR treatment, probably due to FQ, but we have recently shown
that BDQ and LZD do not promptly stop transmission - probably due to their
PKs. However, the NIX regimen for MDR and XDR we recently showed does stop
transmission quickly, like effective first line and standard MDR treatment.

Re. the protection of prior TB exposure - by which you mean prior infection
without disease - of course that is true. Like BCG, prior TB infection
conveys some protection against reinfection through the innate immune
system, so called, learned immunity. But that protection is incomplete and
often overcome by massive exposure. There are many papers showing that in
low-burden outbreak situations, secondary cases result from the previously
uninfected (and unvaccinated), not the previously infected contacts
(usually unvaccinated also). But in high-burden settings that distinction
is hard to see because previously uninfected (and unvaccinated) persons are
uncommon and exposures are frequent, potentially overwhelming the limited
protection of prior TB infection.

We have heard some healthcare workers argue, in fact, that treating latent
infection, while it reduces the risk of reactivation of old infection,
might reduce immunity to new infection. This whole discussion is limited by
the absence of tests for reinfection, but I will continue. There is no
evidence that treating infection increases the risk of reinfection, and
disease - the only indicator of reinfection. If that were true - if living
Mtb were needed for protection - BCG would not convey even the limited
protection that it does since it is usually cleared completely in most
healthy persons. There is now clear evidence that BCG conveys protection
against infection as measured by IGRA conversions. In the recent Cape Town
adolescent study also, a new vaccine was shown to prevent sustained
infection. Likewise, if still viable bacteria were required, killed
vaccines would not be useful against TB, but they have been shown to convey
protection in HIV infected persons in the Dar-Dar study. In summary,
previous infection, like BCG and probably other vaccines, does provide
limited protection against infection and reinfection and, as far as I know,
there is no evidence that that protection is not lost by treating latent
infection.

Ed Nardell

Abdur Razaq Abubakar B. Dikko Replied at 10:01 AM, 23 Oct 2018

I think the question is what do we want to accomplish from confining a
TB patient to a ward? I Concur with the suggestion of Edward Nardell.
Emphasis on TB ward is no longer a priority even here in Developing
countries except for those TB Patients who need hospitalization like
DR TB patients. If well implemented FAST strategy will have more
impact on TB case finding and management than confining the patients
to a ward. I don't really understand the significance of confining
patient to a TB ward from early 48 hrs (after diagnosis) as stated
above.

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