Investigating the distribution of integrons among clinical isolates of acinetobacter baumannii and their association to carbapenem resistance

AbstractAcinetobacter baumannii (A. baumannii) represents a global threat owing to its ability to resist most of the currently available antimicrobial agents. Moreover, emergence of carbapenem resistant A. baumannii (CR-AB) isolates limits the available treatment options. Enzymatic degradation by variety of ß-lactamases, have been identified as the most common mechanism of carbapenem resistance in A. baumannii. The alarming increase in the prevalence of CR-AB necessitates continuous screening and molecular characterization to appreciate the problem. The present study was performed to assess the prevalence and characterize carbapenemases among 206 CR-AB isolated from various clinical specimens collected from different intensive care units at Kasr Al-Aini Hospital.All isolates were confirmed to be A. baumannii by detection of the blaOXA-51-like gene. Molecular screening of 13 common Ambler class bla carbapenemases genes in addition to insertion sequence (IS-1) upstream OXA-23 was performed by using four sets of multiplex PCR, followed by identification using gene sequencing technology. Among the investigated genes, the prevalence of blaOXA-23, and blaOXA-58 were 77.7%, and 1.9%, respectively. The ISAba1 was detected in 10% of the blaOXA-23 positive isolates. The prevalence of metallo-β-lactamases (MBLs) studied; blaNDM-1, blaSPM, blaVIM, blaSIM-1 were 11.7%, 6.3%, 0.5%, and 0.5% respectively. One of class A; bla KPC was detected in 10.7% of the investigated isolates. blaOXA-24/40, blaIMP, blaGES, blaVEB and blaGIM were not detected in any of the studied isolates. Moreover, 18.4% of the isolates have shown to harbor two or more of the screened bla genes. We concluded that the most prevalent type of ß-lactamases genes among CR-AB isolates collected from Egyptian patients were blaOXA-23 followed by blaNDM-1 and blaKPC.Author summaryCarbapenem-resistant A. baumannii has become a real global health threat. The aim of the present study was to characterize and to assess the prevalence of carbapenemases among 206 CR-AB clinical isolates from Egyptian patients. We concluded that the most prevalent type of ß-lactamases genes among CR-AB isolates collected from Egyptian patients were blaOXA-23 followed by blaNDM-1 and blaKPC. In this study, ISAba1 was detected upstream 10% of blaOXA-23 positive isolates only which indicates that the spread of resistance among Acinetobacter isolates could be either chromosomal or plamid-mediated.

Download Full-text

Variability in carbapenemase activity of intrinsic OxaAb (OXA-51-like) β-lactamase enzymes in Acinetobacter baumannii

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dkaa502 ◽

2020 ◽

Author(s):

Yuiko Takebayashi ◽

Jacqueline Findlay ◽

Kate J Heesom ◽

Philip J Warburton ◽

Matthew B Avison ◽

...

Keyword(s):

Molecular Evolution ◽

Acinetobacter Baumannii ◽

Active Site ◽

Carbapenem Resistance ◽

Clinical Isolates ◽

Resistance Factors ◽

Resistance Determinants ◽

Evolution Analysis ◽

Antimicrobial Susceptibility Tests ◽

Susceptibility Tests

Abstract Objectives To measure the variability in carbapenem susceptibility conferred by different OxaAb variants, characterize the molecular evolution of oxaAb and elucidate the contribution of OxaAb and other possible carbapenem resistance factors in the clinical isolates using WGS and LC–MS/MS. Methods Antimicrobial susceptibility tests were performed on 10 clinical Acinetobacter baumannii isolates. Carbapenem MICs were evaluated for all oxaAb variants cloned into A. baumannii CIP70.10 and BM4547, with and without their natural promoters. Molecular evolution analysis of the oxaAb variants was performed using FastTree and SplitsTree4. Resistance determinants were studied in the clinical isolates using WGS and LC–MS/MS. Results Only the OxaAb variants with I129L and L167V substitutions, OxaAb(82), OxaAb(83), OxaAb(107) and OxaAb(110) increased carbapenem MICs when expressed in susceptible A. baumannii backgrounds without an upstream IS element. Carbapenem resistance was conferred with the addition of their natural upstream ISAba1 promoter. LC–MS/MS analysis on the original clinical isolates confirmed overexpression of the four I129L and L167V variants. No other differences in expression levels of proteins commonly associated with carbapenem resistance were detected. Conclusions Elevated carbapenem MICs were observed by expression of OxaAb variants carrying clinically prevalent substitutions I129L and L167V. To drive carbapenem resistance, these variants required overexpression by their upstream ISAba1 promoter. This study clearly demonstrates that a combination of IS-driven overexpression of oxaAb and the presence of particular amino acid substitutions in the active site to improve carbapenem capture is key in conferring carbapenem resistance in A. baumannii and other mechanisms are not required.

Download Full-text

In vitro activity of colistin against multidrug-resistant Acinetobacter baumannii isolates harboring blaOXA-23-like and blaOXA-24-like genes: A multicenter based study

Acta Microbiologica et Immunologica Hungarica ◽

10.1556/030.2020.01031 ◽

2020 ◽

Vol 67 (3) ◽

pp. 182-186

Author(s):

Susan Khanjani ◽

Hadi Sedigh Ebrahim-Saraie ◽

Mohammad Shenagari ◽

Ali Ashraf ◽

Ali Mojtahedi ◽

...

Keyword(s):

Acinetobacter Baumannii ◽

Carbapenem Resistance ◽

Multidrug Resistant ◽

Resistance Rate ◽

Clinical Isolates ◽

Clinical Samples ◽

Cross Sectional ◽

The North ◽

North Of Iran

AbstractThis study was aimed to evaluate occurrence of antibiotic resistance and the presence of resistance determinants among clinical isolates of Acinetobacter baumannii. This cross-sectional study from January to September 2018 was performed on 59 A. baumannii strains isolated from clinical samples in the north of Iran. Isolates were identified by standard microbiologic tests and molecular method. Antimicrobial susceptibility testing was carried out by disk diffusion and broth microdilution methods. The presence of carbapenem resistance genes was detected by PCR method. All isolates were resistant to cefepime, meropenem, imipenem and ceftazidime. The lowest resistance rate was observed against doxycycline with 33.9%. Minimum inhibitory concentration (MIC) results showed that all carbapenem-resistant A. baumannii (CRAB) isolates were susceptible to colistin with MIC50 and MIC90 values of 1/2 µg/mL. Among 59 CRAB, blaOXA-23-like was the most prevalent gene (86.4%) followed by blaOXA-24-like (69.5%). Meanwhile, none of the clinical isolates harbored blaOXA-58-like gene. We found a high prevalence of CRAB strains harboring OXA-type carbapenemases in the north of Iran. Our results suggests that the presence of OXA-type genes was not directly correlated with the increase of imipenem MIC level, but can be clinically important as they contribute to the selection of CRAB strains.

Download Full-text

Novel Acquired Metallo-β-Lactamase Gene, blaSIM-1, in a Class 1 Integron from Acinetobacter baumannii Clinical Isolates from Korea

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.11.4485-4491.2005 ◽

2005 ◽

Vol 49 (11) ◽

pp. 4485-4491 ◽

Cited By ~ 218

Author(s):

Kyungwon Lee ◽

Jong Hwa Yum ◽

Dongeun Yong ◽

Hyuk Min Lee ◽

Heung Dong Kim ◽

...

Keyword(s):

Acinetobacter Baumannii ◽

Tertiary Care ◽

Carbapenem Resistance ◽

Gene Cassette ◽

Clinical Isolates ◽

Care Hospital ◽

Class 1 Integron ◽

Class 1 ◽

Broad Array ◽

Tract Infections

ABSTRACT Carbapenem resistance mediated by acquired carbapenemase genes has been increasingly reported, particularly for clinical isolates of Pseudomonas aeruginosa and Acinetobacter spp. Of 1,234 nonduplicate isolates of carbapenem-resistant Pseudomonas spp. and Acinetobacter spp. isolated at a tertiary-care hospital in Seoul, Korea, 211 (17%) were positive for metallo-β-lactamase (MBL). Of these, 204 (96%) had either the bla IMP-1 or bla VIM-2 allele. In addition, seven Acinetobacter baumannii isolates were found to have a novel MBL gene, which was designated bla SIM-1. The SIM-1 protein has a pI of 7.2, is a new member of subclass B1, and exhibits 64 to 69% identity with the IMP-type MBLs, which are its closest relatives. All SIM-1-producing isolates exhibited relatively low imipenem and meropenem MICs (8 to 16 μg/ml) and had a multidrug resistance phenotype. Expression of the cloned bla SIM-1 gene in Escherichia coli revealed that the encoded enzyme is capable of hydrolyzing a broad array of β-lactams, including penicillins, narrow- to expanded-spectrum cephalosporins, and carbapenems. The bla SIM-1 gene was carried on a gene cassette inserted into a class 1 integron, which included three additional cassettes (arr-3, catB3, and aadA1). The strains were isolated from sputum and urine specimens from patients with pneumonia and urinary tract infections, respectively. All patients had various underlying diseases. Pulsed-field gel electrophoresis of SmaI-digested genomic DNAs showed that the strains belonged to two different clonal lineages, indicating that horizontal transfer of this gene had occurred and suggesting the possibility of further spread of resistance in the future.

Download Full-text

Development of TaqMan real-time polymerase chain reaction for the detection of the newly emerging form of carbapenem resistance gene in clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii

Indian Journal of Medical Microbiology ◽

10.4103/0255-0857.83907 ◽

2011 ◽

Vol 29 (3) ◽

pp. 249 ◽

Cited By ~ 22

Author(s):

V Manchanda ◽

S Gupta ◽

R Chopra ◽

N Verma ◽

IR Kaur ◽

...

Keyword(s):

Escherichia Coli ◽

Polymerase Chain Reaction ◽

Klebsiella Pneumoniae ◽

Acinetobacter Baumannii ◽

Real Time ◽

Resistance Gene ◽

Carbapenem Resistance ◽

Clinical Isolates ◽

Chain Reaction ◽

Polymerase Chain

Download Full-text

Carbapenem Resistance Mediated by Beta-Lactamases in Clinical Isolates of Acinetobacter baumannii in Spain

European Journal of Clinical Microbiology & Infectious Diseases ◽

10.1007/s100960050064 ◽

1998 ◽

Vol 17 (4) ◽

pp. 282-285 ◽

Cited By ~ 1

Author(s):

S. López-Hernández ◽

T. Alarcón ◽

M. López-Brea

Keyword(s):

Acinetobacter Baumannii ◽

Carbapenem Resistance ◽

Clinical Isolates ◽

Beta Lactamases

Download Full-text

Prevalence and Mechanisms of Carbapenem Resistance Among Acinetobacter baumannii Clinical Isolates in Egypt

Microbial Drug Resistance ◽

10.1089/mdr.2018.0141 ◽

2019 ◽

Vol 25 (4) ◽

pp. 480-488 ◽

Cited By ~ 16

Author(s):

Abdalbagi Basheer Benmahmod ◽

Heba Shehta Said ◽

Ramdan Hassan Ibrahim

Keyword(s):

Acinetobacter Baumannii ◽

Carbapenem Resistance ◽

Clinical Isolates

Download Full-text

Genomic Characterization of Extensively Drug-Resistant NDM-Producing Acinetobacter baumannii Clinical Isolates With the Emergence of Novel blaADC-257

Frontiers in Microbiology ◽

10.3389/fmicb.2021.736982 ◽

2021 ◽

Vol 12 ◽

Author(s):

Mai M. Zafer ◽

Amira F. A. Hussein ◽

Mohamed H. Al-Agamy ◽

Hesham H. Radwan ◽

Samira M. Hamed

Keyword(s):

Antimicrobial Resistance ◽

Acinetobacter Baumannii ◽

Resistance Genes ◽

Strong Association ◽

Carbapenem Resistance ◽

Clinical Isolates ◽

Drug Resistant ◽

Missense Mutations ◽

Extensively Drug Resistant ◽

Susceptibility Profiles

Acinetobacter baumannii has become a major challenge to clinicians worldwide due to its high epidemic potential and acquisition of antimicrobial resistance. This work aimed at investigating antimicrobial resistance determinants and their context in four extensively drug-resistant (XDR) NDM-producing A. baumannii clinical isolates collected between July and October 2020 from Kasr Al-Ainy Hospital, Cairo, Egypt. A total of 20 A. baumannii were collected and screened for acquired carbapenemases (blaNDM, blaVIM and blaIMP) using PCR. Four NDM producer A. baumannii isolates were identified and selected for whole-genome sequencing, in silico multilocus sequence typing, and resistome analysis. Antimicrobial susceptibility profiles were determined using disk diffusion and broth microdilution tests. All blaNDM-positive A. baumannii isolates were XDR. Three isolates belonged to high-risk international clones (IC), namely, IC2 corresponding to ST570Pas/1701Oxf (M20) and IC9 corresponding to ST85Pas/ST1089Oxf (M02 and M11). For the first time, we report blaNDM-1 gene on the chromosome of an A. baumannii strain that belongs to sequence type ST164Pas/ST1418Oxf. Together with AphA6, blaNDM-1 was bracketed by two copies of ISAba14 in ST85Pas isolates possibly facilitating co-transfer of amikacin and carbapenem resistance. A novel blaADC allele (blaADC-257) with an upstream ISAba1 element was identified in M19 (ST/CC164Pas and ST1418Oxf/CC234Oxf). blaADC genes harbored by M02 and M11 were uniquely interrupted by IS1008. Tn2006-associated blaOXA-23 was carried by M20. blaOXA-94 genes were preceded by ISAba1 element in M02 and M11. AbGRI3 was carried by M20 hosting the resistance genes aph(3`)-Ia, aac(6`)-Ib`, catB8, ant(3``)-Ia, sul1, armA, msr(E), and mph(E). Nonsynonymous mutations were identified in the quinolone resistance determining regions (gyrA and parC) of all isolates. Resistance to colistin in M19 was accompanied by missense mutations in lpxACD and pmrABC genes. The current study provided an insight into the genomic background of XDR phenotype in A. baumannii recovered from patients in Egypt. WGS revealed strong association between resistance genes and diverse mobile genetic elements with novel insertion sites and genetic organizations.

Download Full-text