Elias Rita, Modesto Ana, Machado Diana, Pereira Bruna, Phelan Jody, Melo-Cristino José, Lito Luís, Gonçalves Luísa, Portugal Isabel, Viveiros Miguel, Campino Susana, Clark Taane G, Duarte Aida, Perdigão João
Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal.
Global Health and Tropical Medicine, Associate Laboratory in Translation and Innovation Towards Global Health, Instituto de Higiene e Medicina Tropical, Universidade NOVA de Lisboa, Lisboa, Portugal.
Med Microbiol Immunol. 2025 Jan 8;214(1):6. doi: 10.1007/s00430-024-00814-y.
\nKlebsiella pneumoniae is a common pathogen of healthcare-associated infections expressing a plethora of antimicrobial resistance loci, including ADP-ribosyltransferase coding genes (arr), able to mediate rifampicin resistance. The latter has activity against a broad range of microorganisms by inhibiting DNA-dependent RNA polymerases. This study aims to characterise the arr distribution and genetic context in 138 clinical isolates of K. pneumoniae and correlate these with rifampicin resistance. All isolates were subjected to whole-genome sequencing for species identification, typing and AMR genes identification, along with the determination of the minimum inhibitory concentration (MIC) of rifampicin. Molecular detection of arr genes and class 1 integrons was performed for rifampicin-resistant isolates. Efflux activity was investigated as a possible determinant of rifampicin resistance in isolates devoid of known genetic determinants. Twelve isolates exhibited high rifampicin MICs (≥ 64 mg/L), 124 showed intermediate MICs (16-32 mg/L) and two displayed low (8 mg/L) MICs. Two arr allelic variants, arr-2 and arr-3, were found across one and nine K. pneumoniae isolates, respectively, all within class 1 integrons, including a newly described integron, and all associated with high rifampicin MICs (≥ 64 mg/L). Elevated resistance levels were additionally linked to increased arr-2/3 expression and closer proximity to the promoter. No arr gene or rpoB mutations were found across the remaining two isolates and no correlation between efflux activity and high-level rifampicin resistance was found for both isolates. In conclusion, this study demonstrates that arr genes confer high levels of rifampicin resistance in K. pneumoniae highlighting its widespread dissemination within class 1 integrons.
肺炎克雷伯菌是医疗保健相关感染的常见病原体，它表达大量抗菌耐药基因座，包括能够介导利福平耐药性的ADP-核糖基转移酶编码基因（arr）。后者通过抑制DNA依赖性RNA聚合酶对多种微生物具有活性。本研究旨在表征138株肺炎克雷伯菌临床分离株中arr的分布和基因背景，并将这些与利福平耐药性相关联。所有分离株均进行全基因组测序以进行菌种鉴定、分型和抗菌药物耐药（AMR）基因鉴定，同时测定利福平的最低抑菌浓度（MIC）。对利福平耐药分离株进行arr基因和1类整合子的分子检测。对于缺乏已知遗传决定因素的分离株，研究了外排活性作为利福平耐药性的可能决定因素。12株分离株表现出高利福平MIC（≥64mg/L），124株表现出中等MIC（16 - 32mg/L），2株表现出低（8mg/L）MIC。在一株和九株肺炎克雷伯菌分离株中分别发现了两种arr等位基因变体arr-2和arr-3，它们均在1类整合子内，包括一个新描述的整合子，并且都与高利福平MIC（≥64mg/L）相关。耐药水平升高还与arr-2/3表达增加以及与启动子距离更近有关。在其余两株分离株中未发现arr基因或rpoB突变，并且两株分离株的外排活性与高水平利福平耐药性之间均未发现相关性。总之，本研究表明arr基因在肺炎克雷伯菌中赋予高水平的利福平耐药性，突出了其在1类整合子中的广泛传播。
