Multidrug-resistant Acinetobacter baumannii strains with NDM-1: Molecular characterization and in vitro efficacy of meropenem-based combinations.

Acinetobacter baumannii is an important cause of hospital-acquired, multidrug-resistant (MDR) infections occurring worldwide. Anti-microbial combination regimens may be the only feasible treatment option for affected patients. In the present study, the efficacy of the combined therapy of meropenem with colistin, ampicillin-sulbactam, tazobactam and vancomycin against clinical strains of MDR A. baumannii was determined. Anti-microbial susceptibility testing was performed and resistance genes were characterized by a multiplex polymerase chain reaction (PCR)-reverse line blot assay. The genetic background of New Delhi metallo-ß-lactamase 1 (NDM-1) was analysed by primer walking. The presence of NDM-1 was detected using the modified Hodge test and the EDTA-combined disk test. To screen for synergistic drug effects, the fractional inhibitory concentration index was calculated using a checkerboard assay. The results of the PCR as well as the sequence analyses suggested that NDM-1 was located downstream of the ISAba125 element. In addition, a synergistic effect was determined for meropenem + vancomycin, meropenem + tazobactam and meropenem + ampicillin + sulbactam in two strains each, and in four strains for meropenem + colistin. A total of five A. baumannii strains with resistance to numerous antibiotics and carrying numerous resistance genes were identified. In the strains of A. baumannii, the NDM-1 gene was integrated in a transposon structure with a copy of the ISAba125 insertion sequence. However, the genetic background was not identical among the different species and strains. The genetic variability of NDM-1 may facilitate the rapid dissemination of this gene. In conclusion, meropenem may enhance the efficacy of antibiotics in A. baumannii strains with NDM-1-associated MDR.

Knockdown of ephrin receptor A7 suppresses the proliferation and metastasis of A549 human lung cancer cells.

Previous studies have demonstrated that ephrin (Eph) family receptor tyrosine kinases and ligands promote cancer growth, invasion and metastasis. In addition, it has been reported that Eph receptor A7 (EphA7) is transcriptionally activated in lung cancer; however, the effects of silencing EphA7 expression on the growth of lung cancer cells, and the underlying molecular mechanisms, have yet to be determined. Therefore, the present study aimed to investigate whether silencing EphA7 with small interfering (si)RNA could induce apoptosis in non­small cell lung cancer (NSCLC) cells. Furthermore, the effects of siEphA7 on cell migration and invasion were evaluated using Transwell assays. The mechanisms underlying the effects of siEphA7 on the tumorigenic properties of A549 cells were also examined. The results of the present study demonstrated that transfection with siEphA7 inhibited the proliferation, migration and invasion of A549 cells. In addition, siEphA7 significantly increased the protein expression levels of B­cell lymphoma 2 (Bcl­2)­associated X protein and caspase­3, and decreased the protein expression levels of Bcl­2, thus suggesting that siEphA7 was able to induce apoptosis via the intrinsic apoptotic pathway. In addition, the expression levels of phosphatase and tensin homolog (PTEN) were significantly upregulated, and the expression levels of total AKT were not altered, whereas the levels of phosphorylated­AKT were reduced. These findings indicated that EphA7 may have an important role in the pathogenesis of NSCLC by regulating PTEN expression via the PTEN/AKT pathway. Silencing EphA7 may provide a novel approach for the treatment of NSCLC.