Versiunea nouă a metodei molecular genetice pentru detecţia tuberculozei, precum şi a rezistenţei la rifampicină şi izoniazidă (Line probe assay genotype mtbdrplus VER2.0)

Testul molecular genetic (Line Probe Assay) disponibil comercial MTBDRplus ver2.0 (Hain Lifescience, Nehren, Germany) a fost evaluat pentru abilitatea de depistare a M.tuberculosis şi mutaţiilor care conferă rezistenţă la Izoniazidă şi Rifampicină direct din specimene clinice microscopic pozitive şi negative. Au fost examinate în total 348 probe: 73.9% dintre care microscopic negative şi 23.3% probe au fost microscopic pozitive. 104 din 257 probe microscopic negative, au fost pozitive prin cultură şi 20 au fost negative şi prin cultură, diagnosticul de tuberculoză la aceşti pacienţi fiind confi rmat prin metode clinice şi radiologice. MTBDRplus ver.2 a demonstrat o sensibilitate de 94.3% şi specificitate de 96.0%. În concluzie, MTBDRplus ver2.0 este un test rapid cu o sensibilitate majoră pentru depistarea M.tuberculosis în specimene clinice microscopic pozitive şi negative, care permite determinarea sensibilităţii către Rifampicină şi Izoniazidă, şi poate uşor fi implementată în practica de rutină a laboratoarelor de profi l

Evaluation of a New Test, GenoType HelicoDR, for Molecular Detection of Antibiotic Resistance in Helicobacter pylori▿

The eradication rate of Helicobacter pylori by standard therapy is decreasing due to antibiotic resistance, mainly to clarithromycin. Our aim was to provide a new molecular test to guide the treatment of new and relapsed cases. We first studied 126 H. pylori strains for phenotypic (MIC) and genotypic resistance to clarithromycin (rrl mutation) and levofloxacin (gyrA mutation) and then developed a DNA strip genotyping test on the basis of the correlation results and literature data. Clinical strains (n = 92) and gastric biopsy specimens containing H. pylori (n = 105) were tested blindly with the new molecular test GenoType HelicoDR. The presence of mutations or the absence of hybridization with wild-type sequences was predictive, in rrl for clarithromycin resistance in 91 cases (mostly the A2147G mutation) and in gyrA for levofloxacin resistance in 58 cases (mutations at codon 87 or 91). Genotyping revealed a mix of genotypes in 33% of the cases, reflecting a coinfection or selection for resistant mutants. The sensitivity and specificity of detecting resistance were 94% and 99% for clarithromycin and 87% and 98.5% for levofloxacin, respectively. The concordance scores were 0.96 for clarithromycin and 0.94 for levofloxacin. With global resistance rates of 46% for clarithromycin and 25% for levofloxacin, which were observed for consecutive positive biopsy specimens from 2007 and 2008, the positive and negative predictive values for detecting resistance were 99% and 94% for clarithromycin and 96% and 96% for fluoroquinolone. GenoType HelicoDR is efficient at detecting mutations predictive of antibiotic resistance in H. pylori when applied to strains or directly to gastric biopsy specimens