MOLECULAR CHARACTERIZATION OF LEISHMANIA DNA FROM ARCHIVED GIEMSA-STAINED SLIDES OF PATIENTS FROM SALTA, ARGENTINA

ALMAZÁN, MARÍA CRISTINA; KROLEWIECKI, ALEJANDRO JAVIER; HOYOS, CARLOS LORENZO; CAJAL, SILVANA PAMELA; COPA, NOEMÍ GRISELDA; FLEITAS, PEDRO; BARROSO, PAOLA ANDREA; MARCO, JORGE DIEGO; NASSER, JULIO RUBÉN; GIL, JOSÉ FERNANDO

New Orleans

Simposio; Sixty-Seventh Annual Meeting. American Society of Tropical Medicine & Hygiene; 2018

Cutaneous leishmaniasis is endemic in the northwestern province ofSalta in Argentina. Leishmania DNA from Giemsa-stained slides of up to12 years in storage of patients from a University based reference centerin Oran, Salta was characterized through PCR-Restriction FragmentLength Polymorphism (RFLP). One hundred smears from individualswith suspicious lesions and epidemiologic exposure plus microbiologicconfirmation through positive microscopy were analyzed. The samples hadbeen originally taken 2, 3, 5, 6 and 12 years prior to performing PCR-RFLP(20 samples from each year) and were maintained at room temperature ina tropical environment. All the cases were classified in a semiquantitativescale for amastigote density, and Leishmanin skin test (LST) results wereincluded. DNA extraction was done applying lysis buffer with proteinaseK, and then DNA was amplified with ribosomal internal transcribed spacer1(ITS1) primers. PCR products were digested with HaeIII enzyme. All PCRpositive smears (74/100) belonged to Viannia subgenus. A statisticallysignificant directly proportional relationship between semiquantitativemicroscopy and PCR results was detected (p < 0.001). All patients hadLST positive results (induration ≥ 5 mm), and the smears of those withpositive but smaller induration (LST < 19 mm) had a higher proportionof positive PCR results. This study determined that smear age did notaffect PCR positivity, which allows retrospective analyzes and suggestssmears might be useful for molecular complementary diagnosis. SinceLeishmania (Viannia) braziliensis is the main circulating species in the studyarea, determining Viannia subgenus in all analyzed samples confirmsprevious findings. PCR positivity showed statistically significant differencesaccording to semiquantitative microscopy, highlighting the importance ofparasite burden in the diagnostic sensitivity of the method. Consideringthat smears of patients with smaller LST induration were more positive inPCR, a negative smear from patients with positive LST response, but < 19mm, could actually represent a false negative smear result.