Department of Clinical Laboratory, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China.
Department of Infectious Disease, Nanjing Drum Tower Hospital, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, China.
Infect Genet Evol. 2024 Nov;125:105669. doi: 10.1016/j.meegid.2024.105669. Epub 2024 Sep 18.
This study aims to analyze the genomic and clinical characteristics of Non-baumannii Acinetobacter strains misidentified as A. baumannii, causing bloodstream infections (BSIs) in our hospital.
Whole genome sequencing was performed and average nucleotide identity (ANI) was analyzed. Susceptibility testing was conducted using micro-broth methods. The distribution of antimicrobial resistance genes (ARGs) and mobile genetic elements (MGEs) was examined using online software tools. The prevalence of virulence factors (VFs) was investigated through nucleotide coding sequence comparisons. Genetic structures of blaOXA genes were analyzed by Gcluster software. Clinical information was collected from electronic medical records for patient characterization.
ANI analysis identified five strains as Acinetobacter pittii, with the remaining four identified as A. geminorum, A. nosocomialis, A. soli and A. bereziniae. The GC content of all isolates was less than 38.9 % except for A. soli 16,294. All Non-baumannii Acinetobacter strains were relatively susceptible to antibiotics, except for one A. pittii isolate. Nine blaOXA variants were identified in seven isolates, with two isolates co-carrying 2 different types of blaOXA. Twenty-four insertion sequences (ISs) were identified, with ISAba and IS17 being the primary ISs. Five A. pittii isolates shared the same genetic structures around blaOXA. Genes related to adherence, immune modulation, and nutritional/metabolic factors were the most frequent. Few VFs were detected in A. soli 16,294 and A.bereziniae 14,325.
The presence of carbapenem hydrolyzing oxacillinase encoding genes did not confer carbapenem resistance, possibly due to the lack of ISs in the blaOXA flanking sequences. Different blaOXA variants within distinct strains shared the same genetic structures, suggesting potential for multidrug resistance development, which warrants our attention.
本研究旨在分析我院血源感染（BSI）中被错误鉴定为鲍曼不动杆菌的非鲍曼不动杆菌不动杆菌菌株的基因组和临床特征。
进行全基因组测序和平均核苷酸同一性（ANI）分析。使用微量肉汤法进行药敏试验。使用在线软件工具检测抗菌药物耐药基因（ARGs）和可移动遗传元件（MGEs）的分布。通过核苷酸编码序列比较研究毒力因子（VF）的流行情况。使用 Gcluster 软件分析 blaOXA 基因的遗传结构。通过电子病历收集临床信息，以进行患者特征描述。
ANI 分析鉴定出 5 株为不动杆菌皮氏亚种，其余 4 株鉴定为 geminorum 不动杆菌、nosocomialis 不动杆菌、soli 不动杆菌和 bereziniae 不动杆菌。除了 A. soli 16,294 之外，所有分离株的 GC 含量均小于 38.9%。所有非鲍曼不动杆菌不动杆菌对大多数抗生素相对敏感，除了一株 A. pittii 分离株。在 7 株分离株中鉴定出 9 种 blaOXA 变体，其中 2 株分离株共同携带 2 种不同类型的 blaOXA。鉴定出 24 种插入序列（ISs），其中 ISAba 和 IS17 是主要的 ISs。5 株 A. pittii 分离株在 blaOXA 周围具有相同的遗传结构。与粘附、免疫调节和营养/代谢因子相关的基因最为常见。在 A. soli 16,294 和 A.bereziniae 14,325 中检测到很少的 VFs。
携带碳青霉烯水解的 oxacillinase 编码基因并不赋予碳青霉烯耐药性，可能是由于 blaOXA 侧翼序列中缺乏 ISs。不同菌株中的不同 blaOXA 变体具有相同的遗传结构，表明可能存在多药耐药性的发展，这值得我们关注。
