Mutational and Phylogenetic Analysis of <i>nfxB</i>Gene in Multidrug-Resistant Clinical Isolates of <i>Pseudomonas aeruginosa</i>Hyperexpressing MexCD-OprJ Efflux Pump

The present study focused on MexCD-OprJ efflux pump and its regulatory gene nfxB in multidrug resistant (MDR) clinical isolates of Pseudomonas aeruginosa collected from Kerala, South India. Semi-quantitative reverse transcription-PCR technique was employed to detect hyperexpression of the efflux pump gene, mexD. Amplicons from nfxB gene of isolates hyperexpressing the efflux pump were sequenced for mutational and phylogenetic analysis. Among 29 isolates of MDR P. aeruginosa, increased mexD transcription was detected in 10.3% of the isolates when compared with P. aeruginosa reference strain, PAO (MTCC-3541). Various synonymous and non-synonymous mutations in nfxB regulatory gene sequences were detected. Notably, mutations detected in the strains designate Pa6 and Pa7 have been found to be novel and are hitherto unreported in GenBank data base. The genetic divergence and homogeneity of the nfxB regulatory gene sequences of mexCD-oprJ operon were clearly apparent in the phylogram generated employing similar sequences retrieved from the public database.

Effect of Qiguiyin Decoction(芪归银方) on Multidrug-Resistant Pseudomonas aeruginosa Infection in Rats

Objective： To investigate the effect of Qiguiyin Decoction （芪归银方, QGYD） on multidrug-resistant Pseudomonas aeruginosa infection in Sprague-Dawley （SD） rats. Methods： A pseudomonal infection model in SD rats was established by injecting multidrug-resistant P. aeruginosa intraperitoneally. Infected rats were randomized into four groups treated with Pure water, QGYD, ceftazidime, or combined QGYD and ceftazidime. Blood samples were obtained from the abdominal aorta. Serum was then collected and analyzed by peptide array for immune responsiveness to multidrug-resistant beta-lactamase proteins, including Verona integronencoded metailo-beta-lactamase 1 （VIM-l）, Sao Paulo metallo-beta-lactamase 1 （SPM-1）, and Temoniera （TEMs）. Blood levels of interleukin-113 （IL-113）, interleukin-4 （IL-4）, and interferon-γ （IFN-γ） were assessed by enzyme-linked immunosorbent assay. Results： QGYD enhanced antibody reactivity against VIM-1 [epitopes 7-11 and 36-40] and TEM-1 [epitopes 26-27, 52-55, and 66-70]. QGYD treatment restored the compromised antibody reactivity against VIM-1 [epitopes 53-54 and 56-58] and SPM-1 [epitopes 16-19 and 82-85] following pseudomonal infection. Serum levels of IL-113 and Thl/＇l-h2 in the rats were significantly elevated following pseudomonal infection （P〈0.05 or P〈0.01）. In contrast, QGYD and combination QGYD and ceftazidime treatment restored the elevated serum IL-1β and Thl/-rh2 levels to normal （P〉0.05）. Conclusions： QGYD improves the immune response to pseudomonal infection in rats by stimulating the production of protective antibodies against drug-resistant proteins VIM-1, SPM-1, and TEM-1. In addition, it protects the immune system and maintains immune responsiveness by restoring IL-1β and Thl/Th2 levels.

扶正解毒化瘀方对脂多糖诱导大鼠肺巨噬细胞的调控作用

目的:观察扶正解毒化瘀方对脂多糖诱导的大鼠肺巨噬细胞中NLRP3炎性体通路及相关炎性反应递质的作用。方法:将大鼠NR8383细胞分为空白组、模型组、扶正解毒化瘀方组、哌拉西林他唑巴坦(TZP)组以及中药+TZP组。用制备扶正解毒化瘀方中药原液作用于脂多糖诱导的大鼠NR8383细胞,采用qPCR和Western blotting分别检测NLRP3炎性体通路的mRNA表达和蛋白水平,酶联免疫吸附试验(ELISA)检测干预前后炎性反应递质的水平。结果:扶正解毒化瘀方组和TZP组均能明显降低NLRP3、Caspase-1和ASC的mRNA表达,2组NLRP3和ASC的蛋白水平明显下降,Caspase-1和IL-1β蛋白水平也有下降趋势。扶正解毒化瘀方组和TZP组均能明显降低IL-18和IL-1β炎性反应递质水平,联合用药有增效作用。结论:扶正解毒化瘀方对NLRP3炎性体作用明确,可能通过NLRP3炎性体通路延缓机体免疫炎性损伤。

多重耐药铜绿假单胞菌Ⅰ类整合子-基因盒的检测与分析

目的检测多重耐药铜绿假单胞菌(multi-drug resistant pseudomonas aeruginosa,MDRPA)携带Ⅰ类整合子-基因盒,分析其与耐药表型的相关性。方法使用K-B纸片扩散法(简称K-B法)进行药敏试验,确定菌株耐药表型;用PCR扩增Ⅰ类整合酶基因及可变区的基因盒,并进行测序及序列分析。结果 23株MDRPA中19株检出Ⅰ类整合酶基因,其中15株携带基因盒,基因盒结构共有6种。其中6株携带aad A4a、3株携带aac A4-cat B8-aad A1、1株携带aac(6’)lai-orfv-aad A1-qac EΔ1-sul、3株携带blaIMP-6-qnr-aac A4-blaOXA-1-aad A1-qac E△1-sul、1株携带permease of ABC transporter gene、1株携带bacteriophage protein gene。在15株携带Ⅰ类整合酶基因盒的可变区中,检出8种耐药基因和2种新型基因盒。结论 MDRPA携带的Ⅰ类整合子-基因盒结构具有多样性,与菌株的多重耐药表型密切相关;检出两种新型基因盒,分别是ABC转运系统蛋白和噬菌体蛋白的编码基因。这两种新型基因盒的功能尚不清楚,特别是它们与菌株耐药性的关系,有待进一步研究。

糖尿病足溃疡感染多重耐药铜绿假单胞菌的危险因素及预后分析

目的探讨糖尿病足溃疡(DFU)感染多重耐药铜绿假单胞菌(MDRPA)的危险因素及其对预后的影响。方法将117例DFU感染铜绿假单胞菌(PA)患者根据是否感染MDRPA分为非MDRPA(N-MDRPA)组和MDRPA组,分析DFU感染MDRPA的危险因素及其对预后的影响。结果入院前抗生素应用史、入院前因同一溃疡住院史和骨髓炎是DFU患者感染MDRPA的独立危险因素。MDRPA组较N-MDRPA组截肢/趾率高(32.6%vs 16.2%,P<0.05),治愈率低(20.9%vs 41.9%,P<0.05)。结论入院前抗生素应用史、入院前因同一溃疡住院史和骨髓炎是DFU患者感染MDRPA的独立危险因素。MDRPA可导致创面预后差,增加截肢/趾风险。