PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 42744097

Investigation of pmrCAB and mcr associated resistance in colistin-resistant A. baumannii isolates.

Bahise Cagla Taskin Dalgic·Elif Seren Tanriverdi·Murat Akkan·İlayda Budak·Gulgun Yenisehirli·Baris Otlu
View original source ↗Export metadata ↓

Abstract

BACKGROUND & OBJECTIVES: Colistin is one of the last-resort antibiotics for multidrug-resistant Acinetobacter baumannii. Increasing resistance to colistin limits treatment options, particularly in intensive care units (ICUs). The aim of this study was to compare the expression levels of pmrC, pmrA, and pmrB, among colistin-resistant and colistin-susceptible clinical A. baumannii isolates, to investigate the presence of plasmid-mediated mcr-1-5 genes, and to determine clonal relationships among colistin-resistant isolates. METHODS: A total of 110 A. baumannii isolates recovered from ICU patients in 2020 were included. Colistin minimum inhibitory concentrations were determined using the broth microdilution method. Expression levels of pmrC, pmrA, and pmrB were analyzed by RT-qPCR and compared with the reference strain A. baumannii ATCC 19606. Colistin-resistant isolates (Group 1) were compared with 10 randomly selected colistin-susceptible isolates (Group 2). Detection of mcr-1-5 genes was performed by in-house multiplex PCR. Clonal relationships among resistant isolates were assessed by PFGE. RESULTS: Colistin resistance was detected in 15.45% (17/110) of isolates. The median relative expression levels of pmrC, pmrB, and pmrA in colistin-resistant isolates were 47.84-fold (IQR: 19.29-67.18), 14.72-fold (IQR: 10.13-16.68), and 8.57-fold (IQR: 5.17-12.82), respectively. In colistin-susceptible isolates, the corresponding median expression levels were 5.32-fold (IQR: 3.60-7.97), 3.29-fold (IQR: 0.85-5.95), and 3.31-fold (IQR: 2.58-6.55). Expression levels were significantly higher in colistin-resistant isolates for pmrC (p < 0.001), pmrB (p = 0.002), and pmrA (p = 0.024). None of the resistant isolates carried mcr-1-5 genes. PFGE analysis revealed 12 distinct genotypes among 17 resistant isolates. INTERPRETATION & CONCLUSIONS: Colistin-resistant A. baumannii isolates exhibited significantly higher expression levels of the pmrC, pmrA, and pmrB genes compared to colistin-susceptible isolates. Among the genes evaluated, pmrC showed the largest effect size and the strongest association with the colistin-resistant phenotype. No changes were found in the mcr-1-5 genes among the isolates studied. Further studies, including genomic and functional analyses, are needed to elucidate the underlying mechanisms of these expression changes and their contribution to colistin resistance.

Explore related subjects

Journal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Bahise Cagla Taskin Dalgic, Elif Seren Tanriverdi, Murat Akkan, &#x130;layda Budak, Gulgun Yenisehirli, Baris Otlu. 2026-09-15. Investigation of pmrCAB and mcr associated resistance in colistin-resistant A. baumannii isolates.. https://doi.org/10.1016/j.ijmmb.2026.101287

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2027

Effectiveness of high-dose versus standard-dose influenza vaccines against hospitalisation according to frailty risk: a prespecified analysis of the randomised trial DANFLU-2.

BACKGROUND: Frailty is a major risk factor for influenza-related complications and can influence vaccine effectiveness. We aimed to assess the relative vaccine effectiveness (rVE) of high-dose (HD-IIV) versus standard-dose inactivated influenza vaccine (SD-IIV) in older adults aged 65 years or older according to frailty risk. METHODS: This study was a prespecified analysis of DANFLU-2, an open-label, individually randomised trial, conducted in Denmark during three consecutive influenza seasons (2022-23, 2023-24, and 2024-25). Adults aged 65 years or older were randomised (1:1) to the HD-IIV or SD-IIV group. The primary endpoint was hospitalisation for influenza or pneumonia. Frailty was defined according to the validated Hospital Frailty Risk Score (HFRS) based on ICD-10 codes within 10 years before randomisation. Participants were stratified into three HFRS categories, namely low (<5 points), intermediate (5-15 points), and high (>15 points) frailty risk. The rVE of HD-IIV versus SD-IIV against the primary endpoint was assessed across prespecified HFRS categories and treating HFRS as a continuous variable. Pearson's chi-square test was used to compare safety events across frailty risk groups and randomisation groups. FINDINGS: Among 332&#x2009;438 randomised participants (mean age 73&#xb7;7 years [SD 5&#xb7;8]; 161&#x2009;538 [48&#xb7;6%] were female), 276&#x2009;173 (83&#xb7;1%) had low frailty risk, 52&#x2009;395 (15&#xb7;8%) had intermediate frailty risk, and 3861 (1&#xb7;2%) had high frailty risk. The primary endpoint of hospitalisation for influenza or pneumonia occurred in 1424 (0&#xb7;5%) of 276&#x2009;173 participants with low frailty risk, 761 (1&#xb7;5%) of 52&#x2009;395 with intermediate frailty risk, and 163 (4&#xb7;2%) of 3861 with high frailty risk (relative risk [RR] for intermediate vs low frailty risk 2&#xb7;8 [95% CI 2&#xb7;6-3&#xb7;1]; RR for high vs low frailty risk 8&#xb7;2 [7&#xb7;0-9&#xb7;6]). HFRS as a continuous variable significantly modified the effect of HD-IIV versus SD-IIV against the primary endpoint with higher rVE estimates with increasing HFRS (pinteraction=0&#xb7;020). The rVE was 0&#xb7;2% (95% CI -10&#xb7;8 to 10&#xb7;2) among those with low frailty risk, 13&#xb7;1% (-0&#xb7;4 to 24&#xb7;8) among those with intermediate frailty risk, and 19&#xb7;9% (-10&#xb7;3 to 42&#xb7;1) among those with high frailty risk. No significant interaction was observed when HFRS was assessed according to the prespecified categorical frailty groups (pinteraction=0&#xb7;17). The proportion of participants with at least one serious adverse event increased across frailty risk groups (13&#x2009;366 [4&#xb7;8%] of 275&#x2009;795 for low frailty risk, 5475 [10&#xb7;5%] of 52&#x2009;315 for intermediate frailty risk, and 777 [20&#xb7;2%] of 3850 for high frailty risk; p<0&#xb7;0001), with similar proportions of serious adverse events in the HD-IIV and SD-IIV groups for each frailty risk group. INTERPRETATION: Among adults aged 65 years or older in Denmark, frailty risk might modify the effects of HD-IIV versus SD-IIV against hospitalisation for influenza or pneumonia, with higher rVE estimates with increasing frailty risk. These findings might support considering high-dose influenza vaccines for frail older adults. However, effect modification was not evident when frailty was assessed using prespecified categorical subgroups, and subgroup-specific estimates were imprecise, with 95% CIs crossing the null. These results should be considered exploratory, warranting further investigation. FUNDING: The DANFLU-2 trial was funded by Sanofi.

Journal Article↗