摘要
      从胸膜液中分离并鉴定了一株对替加环素具有耐药性的皮特不动杆菌临床菌株，该菌株携带blaNDM–1基因和新的blaOXA基因blaOXA–1045。AP2044菌株从其他病原体中获得了两个拷贝的blaNDM–1基因和六个抗生素抗性基因（ARGs）。根据全基因组调查，ARGs的GC比率（50-60%）大于染色体主干的GC比率，表明ARGs是水平转移的。OXA-1045属于OXA-213亚家族，其氨基酸序列与OXA-2113的氨基酸序列具有89%的相似性。然后，克隆blaOXA–1045和blaOXA-213，并使用肉汤微量稀释法测定转化体中β-内酰胺的最小抑制浓度（MIC）。与OXA-213相比，OXA-1045能够降低对哌拉西林和哌拉西林-他唑巴坦的易感性。AP2044菌株在意大利黑加仑菌感染模型中表现出低致病性。结晶紫染色法和扫描电子显微镜（SEM）对浓缩生物膜的观察表明，AP2044菌株是一种弱生物膜产生菌。采用定量逆转录聚合酶链式反应（qRT-PCR）检测耐药结节细胞分裂（RND）外排泵相关基因的表达。adeB和adeJ基因的转录水平显著升高，并与替加环素耐药性相关。因此，我们的基因组和表型研究表明，AP2044菌株具有显著的基因组可塑性和自然转化潜力，这些不寻常细菌中抗生素耐药性的出现应该是未来研究的一个问题。
Abstract
A tigecycline-resistant Acinetobacter pittii clinical strain from pleural fluid carrying a blaNDM–1 gene and a novel blaOXA gene, blaOXA–1045, was isolated and characterized. The AP2044 strain acquired two copies of the blaNDM–1 gene and six antibiotic resistance genes (ARGs) from other pathogens. According to the whole-genome investigation, the GC ratios of ARGs (50–60%) were greater than those of the chromosomal backbone (39.46%), indicating that ARGs were horizontally transferred. OXA-1045 belonged to the OXA-213 subfamily and the amino acid sequence of OXA-1045 showed 89% similarity to the amino acid sequences of OXA-213. Then, blaOXA–1045 and blaOXA–213 were cloned and the minimum inhibitory concentrations (MICs) of β-lactams in the transformants were determined using the broth microdilution method. OXA-1045 was able to confer a reduced susceptibility to piperacillin and piperacillin-tazobactam compared to OXA-213. AP2044 strain exhibited low pathogenicity in Galleria mellonella infection models. The observation of condensed biofilm using the crystal violet staining method and scanning electron microscopy (SEM) suggested that the AP2044 strain was a weak biofilm producer. Quantitative reverse transcription-PCR (qRT-PCR) was used to detect the expression of resistance-nodulation-cell division (RND) efflux pump-related genes. The transcription level of adeB and adeJ genes increased significantly and was correlated with tigecycline resistance. Therefore, our genomic and phenotypic investigations revealed that the AP2044 strain had significant genome plasticity and natural transformation potential, and the emergence of antibiotic resistance in these unusual bacteria should be a concern for future investigations.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9116503/