Mi ZuHuang

Antibiotic resistance determinants of a group of multidrug-resistant Acinetobacter baumannii in China.

A group of Acinetobacter baumannii confers multidrug resistance, but the molecular epidemiology and multidrug resistance mechanisms are poorly understood. Nineteen isolates were identified, and the antimicrobial susceptibility profile was determined using the disc diffusion method. Then, PCR of 78 kinds of resistance-associated genes were performed. A novel variant of blaADC gene: blaADC-67 gene (Genbank accession No. JX169789) was prevalent in all 19 isolates. Moreover, ISAba1 could also provide strong promoter to upregulate the expression of blaADC67 to confer resistance to beta-lactam. This is the first report of emergence of blaADC-67 in A. baumannii worldwide, which might confer resistance to beta-lactam.

Emergence of a novel GyrA variant from a strain of multidrug-resistant Klebsiella pneumoniae isolated from in China

A strain of Klebsiella pneumoniae (NB029) was positive for blaTEM (beta-lactamase gene), aph(3’)Ⅰ(aminoglycoside modifying enzyme gene), gyrA (quinolone resistance gene), trbC (genetic marker of plasmids), tnp513, IS26, IS903 (genetic markers of transposons and insertion sequences), intⅠ1 (genetic marker of integrons), qacE△1 (drug efflux gene) by PCR assays. So these positive genes confer multidrug-resistant phenotype. And the presence of gyrA, confirmed as a novel variant (Genbank accession number: JN232083), was determined by sequencing and Blastsguin algorithm. The double mutations at codon 83 and codon 87 in the quinolone resistance-determining region of the gyrA gene lead to high level quinolone resistance.