In order to determine whether a person is infected with Mycobacterium
tuberculosis, the Mantoux tuberculin skin test (TST) remains the
standard method worldwide. This test is a common precautionary measure to
screen the teachers, health care professionals and international travelers for
tuberculosis (TB). However, reliable
administration and reading of the TST requires standardization of procedures,
training, supervision, and practice. It is performed by intradermally injecting
0.1 ml of tuberculin purified protein derivative (PPD) into the inner surface
of the forearm. The injection should be made with a tuberculin syringe, with
the needle bevel facing upward and inserted as a precise angle and in to depth
in the arm to successfully test for TB.
A team of researchers from University of Washington has created a patch with tiny, biodegradable needles that can
penetrate the skin and precisely deliver a tuberculosis test. Since the depth
of delivery is determined by the length of microneedle, rather than the
needle-insertion angle, there is little room for individual user error. This
test method is painless and relatively easier to administer.
The researchers tested the patch on guinea pigs and found
that after the microneedles were inserted using the patch, the skin reaction
associated with having a TB infection was the same as when using conventional
hypodermic needle. A microneedle patch which is just like putting on a bandage,
has potential as a simpler, more reliable option than the traditional Mantoux
test, especially for children who are needle-shy, or in developing countries
where medical care is limited,
The image shows the comparison of a microneedle
tuberculosis test with a traditional test administered with a hypodermic
needle. The lower images show needle-depth problems that can occur with the
conventional test. Image courtesy: Marco Rolandi, UW
Source: http://onlinelibrary.wiley.com/doi/10.1002/adhm.201300185/abstract
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