ABSTRACT
Objective The purpose of this study was to investigate the correlation between single nucleotide polymorphisms (SNP) of Toll-like receptor 9 (TLR9) and tuberculosis in the Chinese Tibetan population . Methods A total of 613 active tubercu-losis patients and 603 healthy controls were enrolled in this case -control study.Two SNPs in TLR9 (rs187084 and rs5743836) were genotyped using the multiplex ligation detection reaction technique .The association of the SNPs with the susceptibility of TB was inves -tigated using logistic regression analysis . Results There was no statistically significant difference in the allele distribution of rs 187084 G/A between the TB patients and the healthy controls (P=0.668) or correlation between the genotype of rs 187084 and the genetic suscepti-bility of TB ( P >0.05).Dominant, recessive and additive models showed no association of this SNP with TB , either (P >0.05). Conclusion The rs187084 polymorphism of TLR9 is not correlated with the genetic susceptibility of tuberculosis in the Chinese Tibetan population.
ABSTRACT
Objective To investigate the importance of plasmid-mediated quinolone resistance in the development of quinolone resistance in clinical isolates of gram-negative bacteria.Methods A total of 541 consecutive clinical isolates of gram-negative ba- cilli resistant or intermediate to ciprofloxacin were screened for the qnrA gene by PCR.Conjugation experiments were carried out with azide-resistant E.coli J53 as a recipient.The aac(6')-Ib-cr gene was detected.The mutations in the quinolone-resist- ance-determining region (QRDR) of the gyrA and parC genes were identified in qnrA positive strains.Results qnrA was identi- fied in 7 of the 541 strains.Among the qnrA positive strains,5 were Enterobacter cloacae.No qnrA was detected in nonfer- menters.Quinolone resistance was transferred in 4 of 7 qnrA positive strains.Transconjugants had 12-to 125-fold increases in MIC of ciprofloxacin relative to that of the recipient.Seven strains contained qnrA with a nucleotide sequence identical to that originally reported.Two transconjugants with higher ciprofloxacin MICs contained aac(6')-Ib-cr gene.Mutations occurred in the QRDR of the gyrA and parC genes in 5 PCR-positive clinical strains.Conclusions Transferable plasmid-mediated quinolone resistance associated with qnrA is highly prevalent in clinical strains of Enterobacter spp.aac(6')-Ib-cr gene and mutations in the quinolone targets may co-exist with qnrA,which may contribute to the further increase of resistance to quinolones.