(LML) Staining of M. leprae vs. M. tuberculosis and decolorizing with hydrochloric acid

Leprosy Mailing List – July 25,  2014 

Ref.:   (LML)    Staining of M. leprae vs. M. tuberculosis and decolorizing with hydrochloric acid 

From:  Jaison Barreto, Bauru, São Paulo, Brazil

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Dear Pieter

 

There are many problems in the field, concerning to the laboratory confirmation of leprosy diagnosis. All of them comes from the lack of knowledge about the disease. How many professionals know what is Ridley & Jopling Classification today? Or even Madrid Classification? Or Indian Classification? Leprosy becomes a question of "number of lesions". According to this "scientific classification", diffuse infiltration with no visible lepromas (lepra bonita) is not leprosy. And if the patient has only 1 to 5 visible lepromas, shall we classify this person as having PB leprosy? Pure neural leprosy does not exist in this classification. A patient with reaction before MDT is MB, and if the reaction occurs after the start of MDT, this patients will be misclassified as being "PB with reaction"!!! This is an absurd.

 

Many physicians think that leprosy is a skin disease, and just do not know that it is primary from Schwann cells. Indeterminate (or initial) leprosy, with only non myelinated nerve fibres involvement, is very rare, almost always restricted to young children. Also, true Tuberculoid (TT) patients usually does not seek for medical assistance, once the disease is asymptomatic and evolves to self healing. 

 

So, what is the class of patients who we will find, in most instances? Borderline or Lepromatous ones. This group of patients are, indeed, multibacillary, once the disease was not self limited, due to the lack of resistance, partial or total. It is not uncommon to find initial Borderline patients, when the slit skin smears are negative in index points, and sometimes even in the lesions, but many bacilli are hidden inside the cutaneous nerve trunks (sanctuary). As nobody takes a biopsy specimen from cutaneous nerve branches, by ethical reasons, these patients are often misclassified as having PB leprosy, i.e., BT leprosy. Unfortunately, when treated with this regimen, often they suffer for several years from type 1 reaction, and finally a "relapse" occurs, usually after 7 to 10 years. Why should we treat a patient BT with 5 lesions with MDT PB, and with MB another one with 6 lesions? Both have partial resistance to the bacilli, i.e., have the same prognosis!!!

 

Some people, whose defend this classification could say: "Oh, but this classification was based on several papers, when it was observed that most patients with 6 or more lesions had slit skin smears positive, different from those with 5 or less". The question is only one: what is the quality of bacilloscopy in the world? How many laboratories know that staining of leprosy biopsies must be done with Faraco-Fite, and not with Ziehl-Neelsen? 

In the last 7 years, I have been in the field, at least once a month, training health professionals. At the Brazilian state of Mato Grosso do Sul, where bacilloscopy was thought to be almost perfect, i.e., 99% of concordance between the evaluation of the slide in the field and in the state reference, we saw that, indeed, 84% had problems during the process: collection, staining, quality of dyes or interpretation. Bacilloscopy of ear lobes, knees and elbows, only, does not mean that in the lesion (or inside the nerve) there are no bacilli. And, as collection of slit skin smears from the lesions is often difficult to do, usually it is not collected from these sites.

 

Last year, I observed the same problem in 2 different countries, Brazil and Russia: in the state of Mato Grosso, the highest endemic state on leprosy in Brazil, and also in the reference center in Russia. The staining for M. leprosy just did not work, because the biopsy sections were deparaffinized with pure xylol (Ziehl), instead to use oil added to xylol (Faraco-Fite). The result is a catastrophe: negative for AFB, in all Borderline cases, and sometimes even in Lepromatous leprosy.

 

It could be better to forget this pseudoclassification of PB and MB. Once true TT and Indeterminate leprosy is not common, the question is: "Why not to treat all patients with MDT MB, giving a second cycle to those that did not show a complete remission?". I am sure we would avoid many "relapses", sequelae and suffering.

 

 

Regards,

 

 

Jaison Barreto

ILSL, Bauru, Brazil

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LML - S Deepak, B Naafs, S Noto and P Schreuder

LML blog link: http://leprosymailinglist.blogspot.it/

Contact: Dr Pieter Schreuder << editorlml@gmail.com

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