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Heteroresistance to colistin in oxacillinase-producing carbapenem-resistant Acinetobacter baumannii clinical isolates from Gorgan, Northern Iran

Ezadi, F. and Jamali, A. and Heidari, A. and Javid, N. and Ardebili, A. (2020) Heteroresistance to colistin in oxacillinase-producing carbapenem-resistant Acinetobacter baumannii clinical isolates from Gorgan, Northern Iran. Journal of Global Antimicrobial Resistance, 21. pp. 380-385.

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Abstract

Objectives: Colistin resistance rates are rising globally among multidrug-resistant Gram-negative bacilli, including Acinetobacter baumannii (A. baumannii). A new type of resistance � heteroresistance � has also been reported to colistin in clinical A. baumannii isolates. This study investigated the presence of colistin heteroresistance in carbapenem-resistant A. baumannii clinical isolates. Methods: Different clinical specimens from hospitalised patients were investigated for A. baumannii. The MICs to imipenem, meropenem and colistin were determined by broth microdilution. PCR was performed to detect OXA-type carbapenemase genes (blaOXA-23-like, blaOXA-24/40-like, blaOXA-51-like, blaOXA-58-like, and blaOXA-143-like). Heteroresistance to colistin was examined using the population analysis profiles method. Genotypic relatedness of the isolates was analysed by enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR). Results: Overall, 71 A. baumannii isolates were recovered from clinical specimens. Of these, 27 (38.03) and 44 (61.97) isolates were carbapenem-susceptible and carbapenem-resistant, respectively. In addition, 67 (94.36) isolates were susceptible to colistin, with MICs between 0.25�2 μg/mL. Among the 44 selected carbapenem-resistant colistin-susceptible isolates, the frequency of blaOXA-51-like, blaOXA-23-like and blaOXA-24/40-like genes was 100, 77.27 and 43.18, respectively. Nine of 44 (20.45) isolates were characterised as colistin-heteroresistant with subpopulations growing at 6�8 μg/mL, whereas two of 44 (4.54) presented heterogeneous subpopulations growing at up to 1 μg/mL of colistin. ERIC�PCR typing clustered A. baumannii isolates to 10 common types (CT1-CT10) containing isolates from different hospitals and 12 single types (ST1-ST12). Conclusions: A. baumannii with a colistin heteroresistance phenotype was common. This could be of great concern since colistin is often used as a last-resort drug for treating A. baumannii infections, highlighting that care is necessary with colistin monotherapy. In addition, more effective strategies and surveillance are required to confine and prevent the inter-hospital and/or intra-hospital dissemination of A. baumannii between therapeutic centres. © 2019 International Society for Antimicrobial Chemotherapy

Item Type: Article
Additional Information: cited By 0
Uncontrolled Keywords: colistin; imipenem; meropenem, adolescent; adult; aged; antibiotic sensitivity; Article; bacterial gene; bacterium isolate; carbapenem resistant Acinetobacter baumannii; child; colistin resistance; female; human; infant; Iran; male; minimum inhibitory concentration; newborn; nonhuman; priority journal
Subjects: بیماریهای واگیرWC
فارماکولوژی QV
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میکروب شناسی وایمنی شناسی QW
مقالات نمایه شده محققین دانشگاه در سایت ,Web of Science ,Scopus
Divisions: معاونت تحقیقات و فناوری
Depositing User: GOUMS
Date Deposited: 10 Jun 2020 08:56
Last Modified: 10 Jun 2020 08:56
URI: http://eprints.goums.ac.ir/id/eprint/10657

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