[Leish-l] Status of PCR for CL diagnosis

[Ciro Gomes]

Dear All,

Very interesting topic.


I believe that PCR is probably the most sensitive technique for the
diagnosis of leishmaniasis. Especially if you target multicopy kDNA.
However huge limitations must be considered:

1. PCR has a huge variety of methods. Any change in extraction methods,
amplification (PCR x qPCR), DNA target will really change your accuracy.

2. The definition of case is a problem. As there is no gold standard for
the diagnosis of leishmaniasis, different articles will have different
definitions of leishmaniasis and that will change sensitivity and
specificity of PCR.

3. Few diagnostic studies follow the STARD or QUADAS II recommendations.
This makes the utility of PCR techniques published very limited in the
field.  Most studies use a higly controled enviroment.

Our gourp is working on this more pragmatic approach for PCR in tegumentary
leishmanias. However the lack of consensus for this type of study make
recommendations very difficult to make.

Local laboratories will probably need to make their own validation and
compare cost x effectiveness of the exam.


This is what we are working on:

Field Validation of SYBR Green- and TaqMan-Based Real-Time PCR Using Biopsy
and Swab Samples To Diagnose American Tegumentary Leishmaniasis in an Area
Where Leishmania (Viannia) braziliensis Is Endemic.
<https://www.ncbi.nlm.nih.gov/pubmed/27927916>

Gomes CM, Cesetti MV, de Paula NA, Vernal S, Gupta G, Sampaio RN, Roselino
AM.

J Clin Microbiol. 2017 Feb;55(2):526-534. doi: 10.1128/JCM.01954-16. Epub
2016 Dec 7.

Accuracy of mucocutaneous leishmaniasis diagnosis using polymerase chain
reaction: systematic literature review and meta-analysis.
<https://www.ncbi.nlm.nih.gov/pubmed/25946238>

Gomes CM, Mazin SC, Santos ER, Cesetti MV, Bächtold GA, Cordeiro JH,
Theodoro FC, Damasco Fdos S, Carranza SA, Santos Ade O, Roselino AM,
Sampaio RN.

Mem Inst Oswaldo Cruz. 2015 Apr;110(2):157-65. doi:
10.1590/0074-02760140280. Epub 2015 Mar 31. Review.
PMID:25946238Free PMC Article <https://www.ncbi.nlm.nih.gov/pubmed/25946238>



Ciro Martins Gomes, MD - PhD
Professor Adjunto - Dermatologia - Universidade de Brasília-UnB
Pós-doutorado - Faculdade de Medicina de Ribeirão Preto - Universidade de
São Paulo-FMRP-USP
Doutor em Ciências Médicas - Faculdade de Medicina-UnB
Curr lattes: http://lattes.cnpq.br/6837199478107491

2017-03-29 10:09 GMT-03:00 Isra Cruz <isra.cruz at finddx.org>:

> Dear Hugo,
> I do think there is consensus with regard to the advantages of molecular
> tests in CL diagnosis, especially in cases were parasites are scarce, like
> in long duration lesions.
> Molecular diagnosis is much more sensitive than microscopy, and
> specificity will depend on the performance of each laboratory and the
> target selected. However, it is true that there are many different
> protocols for molecular diagnosis, using different targets and platforms,
> and most of them are in house protocols that present variability when
> transferred from one lab to another. And here there is a lack of consensus.
> With regard to experiences with molecular diagnostics for CL in Peru, I
> think both Alejando Llanos Cuentas and Jorge Arevalo can provide you with
> good information.
> I hope this helps.
> All the best,
> Isra
>
>
> Isra Cruz, PhD
> Senior Scientific Officer, Neglected Tropical Diseases Programme
> FIND
> Isra.Cruz at finddx.org
> T +41 (0) 22 710 09 54, M +41 (0) 79 419 98 77
>
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>
> -----Original Message-----
> From: leish-l-bounces at lineu.icb.usp.br [mailto:leish-l-bounces at lineu.
> icb.usp.br] On Behalf Of Hugo Valdivia
> Sent: lundi 27 mars 2017 06:31
> To: Leish-L
> Subject: [Leish-l] Status of PCR for CL diagnosis
>
> Dear colleagues,
>
> We have been recently questioned about the use of PCR for CL  diagnosis
> given that the Peruvian Ministry of health considers microscopy as the
> standard practice for CL diagnosis. In this sense, I would like to hear
> your thoughts about the use of PCR for CL diagnosis, specially from those
> colleagues working in reference diagnostic centers. What I reviewed made me
> think that there is no a consensus yet on the topic.
>
> Thank you for the information that you can provide and hope to see you in
> WL6.
>
> Best regards,
> Hugo O. Valdivia,  BSc, PhD
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