Diversity of polymyxin resistance mechanisms among Acinetobacter baumannii clinical isolates

2017 ◽  
Vol 87 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Raquel Girardello ◽  
Marina Visconde ◽  
Rodrigo Cayô ◽  
Regina Célia Bressan Queiroz de Figueiredo ◽  
Marcelo Alves da Silva Mori ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Resistance Mechanisms ◽  
Clinical Isolates

scholarly journals Colistin resistance in Acinetobacter baumannii is driven by multiple genomic traits: Evaluating the role of ISAba1-driven eptA overexpression among Indian isolates

2021 ◽  
Author(s):  
Saranya Vijayakumar ◽  
Jobin John Jacob ◽  
Karthick Vasudevan ◽  
Baby Abirami Shankar ◽  
Maria Lincy Francis ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Lipid A ◽  
Resistance Mechanisms ◽  
Clinical Isolates ◽  
Colistin Resistance ◽  
Two Component System ◽  
Synonymous Mutations ◽  
Insertional Inactivation ◽  
Indian Isolates

Colistin resistance in Acinetobacter baumannii is mediated by multiple mechanisms. Recently, mutations within pmrAB two component system and overexpression of eptA due to upstream insertion of ISAba1 play a major role. To characterize colistin resistance mechanisms among the clinical isolates of A. baumannii in India. A total of 224 clinical isolates of A. baumannii collected from 2016 to 2019 were included in this study. Mutations within lipid A biosynthesis and pmrAB genes were characterized by Whole Genome Shotgun sequencing. Twenty eight complete genomes were further characterized for insertional inactivation of lpx genes and the association of ISAba1-eptA using hybrid assembly approach. Non-synonymous mutations like M12I in pmrA, A138T and A444V in pmrB and E117K in lpxD were identified. Four of the five colistin resistant A. baumannii isolates had insertion of ISAba1 upstream eptA. No mcr genes were identified. Overall, the present study highlights the diversity of colistin resistance mechanisms in A. baumannii. ISAba1-driven eptA overexpression could be responsible for colistin resistance among Indian isolates of colistin resistant A. baumannii.

scholarly journals In vitro activity of rifabutin against 293 contemporary carbapenem-resistant Acinetobacter baumannii clinical isolates and characterization of rifabutin mode of action and resistance mechanisms

2020 ◽  
Vol 75 (12) ◽  
pp. 3552-3562
Author(s):  
Vincent Trebosc ◽  
Birgit Schellhorn ◽  
Julian Schill ◽  
Valentina Lucchini ◽  
Jacqueline Bühler ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Mode Of Action ◽  
Resistance Mechanisms ◽  
Vitro Activity ◽  
Clinical Isolates ◽  
Oral Drug ◽  
In Vitro Activity ◽  
Carbapenem Resistant ◽  
The Usa

Abstract Background Rifabutin, an oral drug approved to treat Mycobacterium avium infections, demonstrated potent activity against Acinetobacter baumannii in nutrient-limited medium enabled by rifabutin cellular uptake through the siderophore receptor FhuE. Objectives To determine rifabutin in vitro activity and resistance mechanisms in a large panel of A. baumannii isolates. Methods Two hundred and ninety-three carbapenem-resistant A. baumannii clinical isolates collected from Europe, the USA and Asia during 2017–19 were used for MIC determination. Sequencing/genotyping of fhuE, rpoB and arr-2 genes in isolates with elevated rifabutin MIC combined with genetic engineering and gene expression quantification was used to characterize rifabutin’s mode of action and resistance mechanisms. Results Rifabutin showed excellent activity on the strain panel, with an MIC50/90 of 0.008/1 mg/L, and was superior to all other antibiotics tested, including colistin, tigecycline and cefiderocol (MIC90 of 8 mg/L). Rifabutin remained active on resistant subpopulations, including strains resistant to the siderophore–drug conjugate cefiderocol (MIC90 of 2 mg/L, n = 23). At least two independent resistance mechanisms were required to abolish rifabutin activity, which is in line with the dose-dependent mutational resistance frequency reaching 10−9 at rifabutin concentrations at or above 2 mg/L. Conclusions This study demonstrated the potent activity of rifabutin against carbapenem-resistant A. baumannii. We propose that FhuE-mediated active uptake of rifabutin enables activity against rifampicin-resistant isolates. To achieve clinically meaningful strain coverage and to avoid rapid resistance development, rifabutin concentrations ≥2 mg/L are required, something rifabutin oral formulations cannot deliver.

Study of the carbapenem resistance mechanisms in clinical isolates of Acinetobacter baumannii: Comparison of burn and non-burn strains

Burns ◽  
2013 ◽  
Vol 39 (7) ◽  
pp. 1414-1419 ◽  
Author(s):  
Omid Pajand ◽  
Mohammad Ahangarzadeh Rezaee ◽  
Mohammad Reza Nahaei ◽  
Reza Mahdian ◽  
Mohammad Aghazadeh ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Carbapenem Resistance ◽  
Resistance Mechanisms ◽  
Clinical Isolates

scholarly journals Prevalence of OXA-Type β-Lactamase Genes among Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates in Thailand

Antibiotics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 864
Author(s):  
Krit Thirapanmethee ◽  
Thayapa Srisiri-a-nun ◽  
Jantana Houngsaitong ◽  
Preecha Montakantikul ◽  
Piyatip Khuntayaporn ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Tertiary Care ◽  
Carbapenem Resistance ◽  
Resistance Mechanisms ◽  
Clinical Isolates ◽  
Health Concern ◽  
Drug Of Choice ◽  
Carbapenem Resistant ◽  
Resistance Rates ◽  
Tertiary Care Hospitals

Carbapenem-resistant Acinetobacter baumannii (CRAB) is a critical health concern for the treatment of infectious diseases. The aim of this study was to investigate the molecular epidemiology of CRAB emphasizing the presence of oxacillinase (OXA)-type β-lactamase-encoding genes, one of the most important carbapenem resistance mechanisms. In this study, a total of 183 non-repetitive CRAB isolates collected from 11 tertiary care hospitals across Thailand were investigated. As a result, the blaoxa-51-like gene, an intrinsic enzyme marker, was detected in all clinical isolates. The blaoxa-23-like gene was presented in the majority of isolates (68.31%). In contrast, the prevalence rates of blaoxa-40/24-like and blaoxa-58-like gene occurrences in CRAB isolates were only 4.92% and 1.09%, respectively. All isolates were resistant to carbapenems, with 100% resistance to imipenem, followed by meropenem (98.91%) and doripenem (94.54%). Most isolates showed high resistance rates to ciprofloxacin (97.81%), ceftazidime (96.72%), gentamicin (91.26%), and amikacin (80.87%). Interestingly, colistin was found to be a potential drug of choice due to the high susceptibility of the tested isolates to this antimicrobial (87.98%). Most CRAB isolates in Thailand were of ST2 lineage, but some belonged to ST25, ST98, ST129, ST164, ST215, ST338, and ST745. Further studies to monitor the spread of carbapenem-resistant OXA-type β-lactamase genes from A. baumannii in hospital settings are warranted.

Comprehensive study to investigate the role of various aminoglycoside resistance mechanisms in clinical isolates of Acinetobacter baumannii

2017 ◽  
Vol 23 (2) ◽  
pp. 74-79 ◽  
Author(s):  
Vajihe Sheikhalizadeh ◽  
Alka Hasani ◽  
Mohammad Ahangarzadeh Rezaee ◽  
Mohammad Rahmati-yamchi ◽  
Akbar Hasani ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Resistance Mechanisms ◽  
Clinical Isolates ◽  
Aminoglycoside Resistance ◽  
Comprehensive Study

scholarly journals Phenotypic and molecular characterization of Acinetobacter baumannii clinical isolates in Saudi Arabia

2020 ◽  
Vol 13 (2) ◽  
pp. 327
Author(s):  
R Bawazeer ◽  
M Algoribi ◽  
T Abujamel ◽  
L Okdah ◽  
M Alzayer ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Acinetobacter Baumannii ◽  
Molecular Characterization ◽  
Clinical Isolates

scholarly journals 1280. In-Vitro Activity of Cefiderocol, Imipenem/Relebactam, & Ceftazidime/Avibactam in Ceftolozane/Tazobactam Resistant Strains of Multidrug Resistant Pseudomonas aeruginosa

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S655-S655
Author(s):  
Daniel Navas ◽  
Angela Charles ◽  
Amy Carr ◽  
Jose Alexander
Keyword(s):  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Vitro Activity ◽  
Clinical Isolates ◽  
Resistance Testing ◽  
Clinical Samples ◽  
In Vitro Activity ◽  
Carbapenemase Gene ◽  
Resistant Strains

Abstract Background The activity of imipenem/relebactam (I/R), ceftazidime/avibactam (CZA) and cefiderocol (FDC) were evaluated against clinical isolates of multidrug resistant (MDR) strains of P. aeruginosa which was resistant to ceftolozane/tazobactam (C/T). The recent increase of MDR P. aeruginosa strains isolated from clinical samples has prompted research and development of new antimicrobials that can withstand its multiple resistance mechanisms. C/T is an effective option for treatment of MDR P. aeruginosa in our facility with only 10% of resistance in MDR strains, but the emergence of resistance may occur due to the presence of a carbapenemase gene or an ampC mutation. Methods Antimicrobial susceptibility testing for C/T Etest® (bioMérieux, Inc.) were performed on all MDR strains initially screened by the VITEK2® (bioMérieux, Inc.). 10% (n=20) of all MDR isolates were resistant to C/T by the CLSI 2019 breakpoints. These resistant isolates were tested for presence of a carbapenemase gene using the GeneXpert CARBA-R (Cepheid®) PCR and against CZA Etest® (bioMérieux, Inc.) I/R gradient strips (Liofilchem®) and FDC broth microdilution (Thermo Scientific™ Sensititre™). Results A total of 20 clinical isolates of MDR P. aeruginosa resistant to C/T were tested following standardized CLSI protocols and techniques. All 20 isolates were screened for the presence of a carbapenemase gene (blaVIM, blaNDM, blaKPC, blaOXA-48, blaIMP). A blaVIM gene was detected in 6 (30%) out of 20 isolates. FDC demonstrated the greatest activity with 85% (n=17) of susceptible isolates (CLSI MIC <4µg/dL). CZA (CLSI MIC <8µg/dL) and I/R (FDA MIC <2µg/dL) showed 15% (n=3) and 10% (n=2) of susceptible isolates respectively. FDC was active against all 6 blaVIM isolates, where all 6 strains were resistant to CZA and I/R as expected. 3 isolates tested non-susceptible against FDC; additional characterization was not performed at this time. Conclusion Based on these results, FDC demonstrated the greatest in-vitro activity against C/T resistant strains of MDR P. aeruginosa. FDC also demonstrated activity against all 6 MDR P. aeruginosa carrying blaVIM gene. FDC is a strong option to consider on MDR P. aeruginosa strains based on a resistance testing algorithm and a cost/effective protocol. Disclosures All Authors: No reported disclosures

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