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Background & objectives: Rapid detection of drug resistance in Mycobacterium tuberculosis (MTB) is essential for the efficient control of tuberculosis. Hence, in this study a nested-allele-specific (NAS) PCR, nested multiple allele-specific PCR (NMAS-PCR) and multiple allele-specific (MAS) PCR assays were evaluated that enabled detection of the most common mutations responsible for isoniazid (INH) and rifampicin (RIF) resistance in MTB isolates directly from clinical specimens. Methods: Six pairs of primers, mutated and wild type, were used for the six targets such as codon 516, 526 and 531 of rpoB, codon 315 of katG and C15-T substitution in the promoter region of mabA-inhA using allele-specific (AS) PCR assays (NAS-PCR, NMAS-PCR and MAS-PCR). The performance of AS PCR method was compared with phenotypic drug susceptibility testing (DST). Results: The usefulness of AS PCR assays was evaluated with 391 clinical specimens (251 Acid fast bacilli smear positive and MTB culture positive; 93 smear negative and MTB culture positive; 47 smear positive and MTB culture negative) and 344 MTB culture positive isolates. With culture-based phenotypic DST as a reference standard, the sensitivity and specificity of the NAS-PCR, NMAS-PCR and MAS-PCR assay for drug resistance-related genetic mutation detection were 98.6 and 97.8 per cent for INH, 97.5 and 97.9 per cent for RIF and 98.9 and 100 per cent for multidrug resistance (MDR). Interpretation & conclusions: The performance of AS PCR assays showed that those could be less expensive and technically executable methods for rapid detection of MDR-TB directly from clinical specimens.
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Objective To study the relationship between gene polymorphism of apolipoprotein E (apolipoproteinE,ApoE)of peripheral blood and Mycoplasma pneumoniae infection in children.Methods Collected 236 cases serum of inpatient and outpatient screening in children with Mycoplasma pneumoniae infection and healthy children between March 2011 and March 2014 in the First Affiliated Hospital of Xi’an Medical University and Xi’an Children’s Hospital,at the age of 3~8 years old,divided into two groups:110 cases of control group and 126 cases of Mycoplasma pneumoniae infection in chil-dren.Used multiple allele-specific PCR (multi-AS PCR)to detect gene polymorphism of ApoE in each group.Results ApoE gene was polymorphic and 6 genotypes:3 homozygous (ε2/2,ε3/3,ε4/4)and 3 heterozygote (ε3/2,ε3/4,ε4/2).Theε3/2 had four bands,ε3/3,ε3/4 and 4/2 had three bands,ε2/2 andε4/4 had two bands.ε3/3 of ApoE genotype distribution in two groups was the most common,control group was 66.7%,infection group was 46.4%.Allele frequencies ofε3 and genotype frequencies ofε3/3 inMycoplasmapneumoniae infection of children were lower than those in control group (P<0.05).But allele frequencies ofε4 and genotype frequency ofε4/4 in Mycoplasma pneumoniae infection of children were increased, which were compared with those in control group (P<0.05).Conclusion There were an association between ApoE gene polymorphism and the incidence of Mycoplasma pneumoniae infection in children.Allelesε3 seems to be a protective factor and allelesε4 may contribute to the development of Mycoplasma pneumoniae infection of children.