Nwabor Lois Chinwe, Chukamnerd Arnon, Nwabor Ozioma Forstinus, Surachat Komwit, Pomwised Rattanaruji, Jeenkeawpiam Kongpop, Chusri Sarunyou
Department of Biomedical Sciences and Biomedical Engineering, Faculty of Medicine, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
Division of Infectious Diseases, Department of Internal Medicine, Faculty of Medicine, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
Heliyon. 2024 Mar 6;10(6):e27326. doi: 10.1016/j.heliyon.2024.e27326. eCollection 2024 Mar 30.
Carbapenem-resistant (CRAB) is an urgent concern to public health. This study focuses on exploring the resistance mechanisms and the in vitro results of using rifampicin in combination with conventional antibiotics for the management of CRAB.
The synergistic and bactericidal effects of rifampicin with conventional antibiotics were evaluated using chequerboard assay and time-kill assay, while the phenotypic and genotypic characteristics of resistant determinants were performed by efflux pump detection and whole genome sequencing on 29 isolates from ICU patients with underlying health diseases.
The isolates showed multidrug resistance, with over 60% showing addictive responses to rifampicin-based combinations at FICI ranging from 0.6 to 0.8. The time-kill assay revealed 99 % killing for rifampicin and minocycline combination in one isolate at 1/4 MIC rifampicin plus 1/4 MIC minocycline, while a bacteriostatic effect was observed at 1/2 MIC rifampici plus 1/2 MIC for a second isolate. Combination with tigecycline resulted in a 99% killing in two out of three isolates with a 2.5-3 log reduction in CFU at 1/4 MIC rifampicin plus 1/4 MIC tigecycline. Rifampicin plus colistin exhibited bactericidal activity against three out of four isolates. The combinations of rifampicin with ciprofloxacin, chloramphenicol, and trimethoprim-sulfamethoxazole were ineffective against the isolates. In addition, a 4-fold reduction in rifampicin MIC was observed in 2 out of 14 isolates in the presence of an efflux pump inhibitor. The pan-genome study demonstrated a progressive evolution with an accessory genome estimated to cover 58% of the matrix. Seven of the ten sequenced isolates belong to sequence type 2 (ST2), while one isolate each was assigned to ST164, ST16, and ST25. Furthermore, 11 plasmids, 34 antimicrobial resistance (AMR) genes, and 65 virulence-associated genes were predicted from the whole genome data. The , , , , , and were prevalent among the isolates. Sequence alignment of the bacteria genome to the reference strain revealed a deleterious mutation in the gene of 4 isolates.
The study suggests that rifampicin in combination with either minocycline, tigecycline, or colistin might be a treatment option for CRAB clinical isolates. In addition, genotypic analysis of the bacteria isolates may inform the clinician of the suitable drug regimen for the management of specific bacteria variants.
耐碳青霉烯类鲍曼不动杆菌（CRAB）是公共卫生领域的一个紧迫问题。本研究着重探讨CRAB的耐药机制以及利福平与传统抗生素联合用于治疗CRAB的体外试验结果。
采用棋盘法和时间杀菌试验评估利福平与传统抗生素的协同和杀菌作用，同时通过外排泵检测以及对29株来自患有基础疾病的重症监护病房（ICU）患者的分离菌株进行全基因组测序，来检测耐药决定因素的表型和基因型特征。
这些分离菌株呈现多重耐药，超过60%的菌株对基于利福平的联合用药在FICI为0.6至0.8时表现出相加反应。时间杀菌试验显示，在一株菌中，利福平与米诺环素联合使用，在利福平1/4 MIC加米诺环素1/4 MIC时杀菌率达99%，而在另一株菌中，在利福平1/2 MIC加米诺环素1/2 MIC时观察到抑菌作用。与替加环素联合使用时，在三株菌中有两株在利福平1/4 MIC加替加环素1/4 MIC时CFU减少2.5 - 3个对数级，杀菌率达99%。利福平加黏菌素对四株菌中的三株表现出杀菌活性。利福平与环丙沙星、氯霉素以及复方磺胺甲恶唑的联合用药对这些分离菌株无效。此外，在存在外排泵抑制剂的情况下，14株菌中有2株利福平MIC降低了4倍。泛基因组研究表明存在渐进性进化，辅助基因组估计覆盖矩阵的58%。测序的10株菌中有7株属于序列型2（ST2），而另外一株分别属于ST164、ST16和ST25。此外，从全基因组数据预测出11个质粒、34个抗菌耐药（AMR）基因和65个毒力相关基因。blaOXA - 23、blaOXA - 51、blaOXA - 58、blaNDM、blaIMP和blaVIM在这些分离菌株中普遍存在。将细菌基因组与参考菌株进行序列比对，发现4株菌的rpoB基因存在有害突变。
该研究表明，利福平与米诺环素、替加环素或黏菌素联合使用可能是CRAB临床分离菌株的一种治疗选择。此外，对细菌分离株进行基因型分析可为临床医生提供针对特定细菌变体管理的合适药物方案信息。
