CRISPR-Cas9 and CRISPR-Assisted Cytidine Deaminase Enable Precise and Efficient Genome Editing inKlebsiella pneumoniae

ABSTRACTKlebsiella pneumoniaeis a promising industrial microorganism as well as a major human pathogen. The recent emergence of carbapenem-resistantK. pneumoniaehas posed a serious threat to public health worldwide, emphasizing a dire need for novel therapeutic means against drug-resistantK. pneumoniae. Despite the critical importance of genetics in bioengineering, physiology studies, and therapeutic-means development, genome editing, in particular, the highly desirable scarless genetic manipulation inK. pneumoniae, is often time-consuming and laborious. Here, we report a two-plasmid system, pCasKP-pSGKP, used for precise and iterative genome editing inK. pneumoniae. By harnessing the clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 genome cleavage system and the lambda Red recombination system, pCasKP-pSGKP enabled highly efficient genome editing inK. pneumoniaeusing a short repair template. Moreover, we developed a cytidine base-editing system, pBECKP, for precise C→T conversion in both the chromosomal and plasmid-borne genes by engineering the fusion of the cytidine deaminase APOBEC1 and a Cas9 nickase. By using both the pCasKP-pSGKP and the pBECKP tools, theblaKPC-2gene was confirmed to be the major factor that contributed to the carbapenem resistance of a hypermucoviscous carbapenem-resistantK. pneumoniaestrain. The development of the two editing tools will significantly facilitate the genetic engineering ofK. pneumoniae.IMPORTANCEGenetics is a key means to study bacterial physiology. However, the highly desirable scarless genetic manipulation is often time-consuming and laborious for the major human pathogenK. pneumoniae. We developed a CRISPR-Cas9-mediated genome-editing method and a cytidine base-editing system, enabling rapid, highly efficient, and iterative genome editing in both industrial and clinically isolatedK. pneumoniaestrains. We applied both tools in dissecting the drug resistance mechanism of a hypermucoviscous carbapenem-resistantK. pneumoniaestrain, elucidating that theblaKPC-2gene was the major factor that contributed to the carbapenem resistance of the hypermucoviscous carbapenem-resistantK. pneumoniaestrain. Utilization of the two tools will dramatically accelerate a wide variety of investigations in diverseK. pneumoniaestrains and relevantEnterobacteriaceaespecies, such as gene characterization, drug discovery, and metabolic engineering.

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Rapid Increase in Prevalence of Carbapenem-ResistantEnterobacteriaceae(CRE) and Emergence of Colistin Resistance Genemcr-1in CRE in a Hospital in Henan, China

Journal of Clinical Microbiology ◽

10.1128/jcm.01932-17 ◽

2018 ◽

Vol 56 (4) ◽

Cited By ~ 17

Author(s):

Yi Li ◽

Qiao-ling Sun ◽

Yingbo Shen ◽

Yangjunna Zhang ◽

Jun-wen Yang ◽

...

Keyword(s):

Klebsiella Pneumoniae ◽

Carbapenem Resistance ◽

Clinical Samples ◽

New Delhi ◽

Colistin Resistance ◽

Large Hospital ◽

Content Type ◽

Carbapenem Resistant ◽

Recent Emergence ◽

Almost All

ABSTRACTThe global spread of carbapenem-resistantEnterobacteriaceae(CRE) is one of the most severe threats to human health in a clinical setting. The recent emergence of plasmid-mediated colistin resistance genemcr-1among CRE strains greatly compromises the use of colistin as a last resort for the treatment of infections caused by CRE. This study aimed to understand the current epidemiological trends and characteristics of CRE from a large hospital in Henan, the most populous province in China. From 2014 to 2016, a total of 7,249Enterobacteriaceaeisolates were collected from clinical samples, among which 18.1% (1,311/7,249) were carbapenem resistant. Carbapenem-resistantKlebsiella pneumoniaeand carbapenem-resistantEscherichia coliwere the two most common CRE species, withKlebsiella pneumoniaecarbapenemases (KPC) and New Delhi metallo-β-lactamases (NDM), respectively, responsible for the carbapenem resistance of the two species. Notably, >57.0% (n= 589) of theK. pneumoniaeisolates from the intensive care unit were carbapenem resistant. Furthermore,blaNDM-5andmcr-1were found to coexist in oneE. coliisolate, which exhibited resistance to almost all tested antibiotics. Overall, we observed a significant increase in the prevalence of CRE isolates during the study period and suggest that carbapenems may no longer be considered to be an effective treatment for infections caused byK. pneumoniaein the studied hospital.

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Multicenter Clinical and Molecular Epidemiological Analysis of Bacteremia Due to Carbapenem-Resistant Enterobacteriaceae (CRE) in the CRE Epicenter of the United States

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02349-16 ◽

2017 ◽

Vol 61 (4) ◽

Cited By ~ 98

Author(s):

Michael J. Satlin ◽

Liang Chen ◽

Gopi Patel ◽

Angela Gomez-Simmonds ◽

Gregory Weston ◽

...

Keyword(s):

New York ◽

Empirical Therapy ◽

Carbapenem Resistance ◽

The United States ◽

Resistance Mechanisms ◽

Rapid Diagnostics ◽

Multicenter Studies ◽

Content Type ◽

Medical Centers ◽

Carbapenem Resistant

ABSTRACT Although the New York/New Jersey (NY/NJ) area is an epicenter for carbapenem-resistant Enterobacteriaceae (CRE), there are few multicenter studies of CRE from this region. We characterized patients with CRE bacteremia in 2013 at eight NY/NJ medical centers and determined the prevalence of carbapenem resistance among Enterobacteriaceae bloodstream isolates and CRE resistance mechanisms, genetic backgrounds, capsular types (cps), and antimicrobial susceptibilities. Of 121 patients with CRE bacteremia, 50% had cancer or had undergone transplantation. The prevalences of carbapenem resistance among Klebsiella pneumoniae, Enterobacter spp., and Escherichia coli bacteremias were 9.7%, 2.2%, and 0.1%, respectively. Ninety percent of CRE were K. pneumoniae and 92% produced K. pneumoniae carbapenemase (KPC-3, 48%; KPC-2, 44%). Two CRE produced NDM-1 and OXA-48 carbapenemases. Sequence type 258 (ST258) predominated among KPC-producing K. pneumoniae (KPC-Kp). The wzi154 allele, corresponding to cps-2, was present in 93% of KPC-3-Kp, whereas KPC-2-Kp had greater cps diversity. Ninety-nine percent of CRE were ceftazidime-avibactam (CAZ-AVI)-susceptible, although 42% of KPC-3-Kp had an CAZ-AVI MIC of ≥4/4 μg/ml. There was a median of 47 h from bacteremia onset until active antimicrobial therapy, 38% of patients had septic shock, and 49% died within 30 days. KPC-3-Kp bacteremia (adjusted odds ratio [aOR], 2.58; P = 0.045), cancer (aOR, 3.61, P = 0.01), and bacteremia onset in the intensive care unit (aOR, 3.79; P = 0.03) were independently associated with mortality. Active empirical therapy and combination therapy were not associated with survival. Despite a decade of experience with CRE, patients with CRE bacteremia have protracted delays in appropriate therapies and high mortality rates, highlighting the need for rapid diagnostics and evaluation of new therapeutics.

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Complete Sequence of pOZ176, a 500-Kilobase IncP-2 Plasmid Encoding IMP-9-Mediated Carbapenem Resistance, from Outbreak Isolate Pseudomonas aeruginosa 96

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00423-13 ◽

2013 ◽

Vol 57 (8) ◽

pp. 3775-3782 ◽

Cited By ~ 48

Author(s):

Jianhui Xiong ◽

David C. Alexander ◽

Jennifer H. Ma ◽

Maxime Déraspe ◽

Donald E. Low ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Carbapenem Resistance ◽

Complete Sequence ◽

Open Reading Frames ◽

Content Type ◽

Conserved Sequence ◽

Carbapenem Resistant ◽

Class 1 ◽

Usage Analysis ◽

Type 3

ABSTRACTPseudomonas aeruginosa96 (PA96) was isolated during a multicenter surveillance study in Guangzhou, China, in 2000. Whole-genome sequencing of this outbreak strain facilitated analysis of its IncP-2 carbapenem-resistant plasmid, pOZ176. The plasmid had a length of 500,839 bp and an average percent G+C content of 57%. Of the 618 predicted open reading frames, 65% encode hypothetical proteins. The pOZ176 backbone is not closely related to any plasmids thus far sequenced, but some similarity to pQBR103 ofPseudomonas fluorescensSBW25 was observed. Two multiresistant class 1 integrons and several insertion sequences were identified. TheblaIMP-9-carrying integron containedaacA4→blaIMP-9→aacA4, flanked upstream by Tn21 tnpMRAand downstream by a completetnioperon of Tn402and amermodule, named Tn6016. The second integron carriedaacA4→catB8a→blaOXA-10and was flanked by Tn1403-liketnpRAand asul1-type 3′ conserved sequence (3′-CS), named Tn6217. Other features include three resistance genes similar to those of Tn5, a tellurite resistance operon, and twopiloperons. The replication and maintenance systems exhibit similarity to a genomic island ofRalstonia solanacearumGM1000. Codon usage analysis suggests the recent acquisition ofblaIMP-9. The origins of the integrons on pOZ176 indicated separate horizontal gene transfer events driven by antibiotic selection. The novel mosaic structure of pOZ176 suggests that it is derived from environmental bacteria.

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An Efficient, Rapid, and Recyclable System for CRISPR-Mediated Genome Editing in Candida albicans

mSphere ◽

10.1128/mspheredirect.00149-17 ◽

2017 ◽

Vol 2 (2) ◽

Cited By ~ 33

Author(s):

Namkha Nguyen ◽

Morgan M. F. Quail ◽

Aaron D. Hernday

Keyword(s):

Candida Albicans ◽

Genome Editing ◽

Fungal Pathogen ◽

Gene Knockout ◽

Strain Engineering ◽

Molecular Genetic Analysis ◽

Content Type ◽

Highly Efficient ◽

Discovery Research ◽

Gene Knockouts

ABSTRACT Candida albicans is the most common fungal pathogen of humans. Historically, molecular genetic analysis of this important pathogen has been hampered by the lack of stable plasmids or meiotic cell division, limited selectable markers, and inefficient methods for generating gene knockouts. The recent development of clustered regularly interspaced short palindromic repeat(s) (CRISPR)-based tools for use with C. albicans has opened the door to more efficient genome editing; however, previously reported systems have specific limitations. We report the development of an optimized CRISPR-based genome editing system for use with C. albicans. Our system is highly efficient, does not require molecular cloning, does not leave permanent markers in the genome, and supports rapid, precise genome editing in C. albicans. We also demonstrate the utility of our system for generating two independent homozygous gene knockouts in a single transformation and present a method for generating homozygous wild-type gene addbacks at the native locus. Furthermore, each step of our protocol is compatible with high-throughput strain engineering approaches, thus opening the door to the generation of a complete C. albicans gene knockout library. IMPORTANCE Candida albicans is the major fungal pathogen of humans and is the subject of intense biomedical and discovery research. Until recently, the pace of research in this field has been hampered by the lack of efficient methods for genome editing. We report the development of a highly efficient and flexible genome editing system for use with C. albicans. This system improves upon previously published C. albicans CRISPR systems and enables rapid, precise genome editing without the use of permanent markers. This new tool kit promises to expedite the pace of research on this important fungal pathogen.

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High-Level Carbapenem Resistance in OXA-232-Producing Raoultella ornithinolytica Triggered by Ertapenem Therapy

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01335-19 ◽

2019 ◽

Vol 64 (1) ◽

Cited By ~ 2

Author(s):

Alina Iovleva ◽

Roberta T. Mettus ◽

Christi L. McElheny ◽

Marissa P. Griffith ◽

Mustapha M. Mustapha ◽

...

Keyword(s):

Rapid Development ◽

Carbapenem Resistance ◽

Resistant Isolate ◽

Clinical Microbiology Laboratory ◽

Loss Of Function ◽

Content Type ◽

Carbapenem Resistant ◽

Class D ◽

Fold Reduction ◽

High Level

ABSTRACT OXA-232 is an OXA-48-group class D β-lactamase that hydrolyzes expanded-spectrum cephalosporins and carbapenems at low levels. Clinical strains producing OXA-232 are sometimes susceptible to carbapenems, making it difficult to identify them in the clinical microbiology laboratory. We describe the development of carbapenem resistance in sequential clinical isolates of Raoultella ornithinolytica carrying blaOXA-232 in a hospitalized patient, where the ertapenem MIC increased from 0.5 μg/ml to 512 μg/ml and the meropenem MIC increased from 0.125 μg/ml to 32 μg/ml during the course of ertapenem therapy. Whole-genome sequencing (WGS) analysis identified loss-of-function mutations in ompC and ompF in carbapenem-resistant isolates that were not present in the initial carbapenem-susceptible isolate. Complementation of a carbapenem-resistant isolate with an intact ompF gene resulted in 16- to 32-fold reductions in carbapenem MICs, whereas complementation with intact ompC resulted in a 2-fold reduction in carbapenem MICs. Additionally, blaOXA-232 expression increased 2.9-fold in a carbapenem-resistant isolate. Rapid development of high-level carbapenem resistance in initially carbapenem-susceptible OXA-232-producing R. ornithinolytica under selective pressure from carbapenem therapy highlights the diagnostic challenges in detecting Enterobacteriaceae strains producing this inefficient carbapenemase.

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Target-AID-Mediated Multiplex Base Editing in Porcine Fibroblasts

10.20944/preprints202109.0362.v1 ◽

2021 ◽

Author(s):

Soo-Young Yum ◽

Goo Jang ◽

Okjae Koo

Keyword(s):

Genome Editing ◽

Cytidine Deaminase ◽

Chromosomal Rearrangements ◽

Dna Breaks ◽

Base Editing ◽

Multiple Loci ◽

Double Strand Dna Breaks ◽

Protospacer Adjacent Motif ◽

Motif Site ◽

Programmable Nucleases

Multiplex genome editing may induce genotoxicity and chromosomal rearrangements due to double-strand DNA breaks at multiple loci simultaneously induced by programmable nucleases, including CRISPR/Cas9. However, recently developed base-editing systems can directly substitute target sequences without double-strand breaks. Thus, the base-editing system is expected to be a safer method for multiplex genome-editing platforms for livestock. Target-AID is a base editing system composed of PmCDA1, a cytidine deaminase from sea lampreys, fused to Cas9 nickase. It can be used to substitute cytosine for thymine in 3-5 base editing windows, 18 bases upstream of the protospacer-adjacent motif site. In the current study, we demonstrated Target-AID-mediated base editing in porcine cells for the first time. We targeted multiple loci in the porcine genome using the Target-AID system and successfully induced target-specific base substitutions with up to 63.15% efficiency. This system can be used for the further production of various genome-engineered pigs.

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Dynamics of blaKPC-2 Dissemination from Non-CG258 Klebsiella pneumoniae to Other Enterobacterales via IncN Plasmids in an Area of High Endemicity

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01743-20 ◽

2020 ◽

Vol 64 (12) ◽

Cited By ~ 1

Author(s):

Ana M. Rada ◽

Elsa De La Cadena ◽

Carlos Agudelo ◽

Cesar Capataz ◽

Nataly Orozco ◽

...

Keyword(s):

Public Health ◽

Klebsiella Pneumoniae ◽

Neonatal Intensive Care ◽

Carbapenem Resistance ◽

Health Interventions ◽

Global Public Health ◽

Public Health Interventions ◽

Content Type ◽

Carbapenem Resistant ◽

Long Read

ABSTRACT Carbapenem-resistant Enterobacterales (CRE) pose a significant threat to global public health. The most important mechanism for carbapenem resistance is the production of carbapenemases. Klebsiella pneumoniae carbapenemase (KPC) represents one of the main carbapenemases worldwide. Complex mechanisms of blaKPC dissemination have been reported in Colombia, a country with a high endemicity of carbapenem resistance. Here, we characterized the dynamics of dissemination of blaKPC gene among CRE infecting and colonizing patients in three hospitals localized in a highly endemic area of Colombia (2013 and 2015). We identified the genomic characteristics of KPC-producing Enterobacterales recovered from patients infected/colonized and reconstructed the dynamics of dissemination of blaKPC-2 using both short and long read sequencing. We found that spread of blaKPC-2 among Enterobacterales in the participating hospitals was due to intra- and interspecies horizontal gene transfer (HGT) mediated by promiscuous plasmids associated with transposable elements that was originated from a multispecies outbreak of KPC-producing Enterobacterales in a neonatal intensive care unit. The plasmids were detected in isolates recovered in other units within the same hospital and nearby hospitals. The gene “epidemic” was driven by IncN-pST15-type plasmids carrying a novel Tn4401b structure and non-Tn4401 elements (NTEKPC) in Klebsiella spp., Escherichia coli, Enterobacter spp., and Citrobacter spp. Of note, mcr-9 was found to coexist with blaKPC-2 in species of the Enterobacter cloacae complex. Our findings suggest that the main mechanism for dissemination of blaKPC-2 is HGT mediated by highly transferable plasmids among species of Enterobacterales in infected/colonized patients, presenting a major challenge for public health interventions in developing countries such as Colombia.

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Sulfamoyl Heteroarylcarboxylic Acids as Promising Metallo-β-Lactamase Inhibitors for Controlling Bacterial Carbapenem Resistance

mBio ◽

10.1128/mbio.03144-19 ◽

2020 ◽

Vol 11 (2) ◽

Cited By ~ 4

Author(s):

Jun-ichi Wachino ◽

Wanchun Jin ◽

Kouji Kimura ◽

Hiromasa Kurosaki ◽

Ayato Sato ◽

...

Keyword(s):

Infectious Diseases ◽

Liver Microsomes ◽

Carbapenem Resistance ◽

Bloodstream Infections ◽

Zinc Ion ◽

Clinical Settings ◽

Content Type ◽

Charged Amino Acids ◽

Carbapenem Resistant ◽

Considerable Benefit

ABSTRACT Production of metallo-β-lactamases (MBLs), which hydrolyze carbapenems, is a cause of carbapenem resistance in Enterobacteriaceae. Development of effective inhibitors for MBLs is one approach to restore carbapenem efficacy in carbapenem-resistant Enterobacteriaceae (CRE). We report here that sulfamoyl heteroarylcarboxylic acids (SHCs) can competitively inhibit the globally spreading and clinically relevant MBLs (i.e., IMP-, NDM-, and VIM-type MBLs) at nanomolar to micromolar orders of magnitude. Addition of SHCs restored meropenem efficacy against 17/19 IMP-type and 7/14 NDM-type MBL-producing Enterobacteriaceae to satisfactory clinical levels. SHCs were also effective against IMP-type MBL-producing Acinetobacter spp. and engineered Escherichia coli strains overproducing individual minor MBLs (i.e., TMB-2, SPM-1, DIM-1, SIM-1, and KHM-1). However, SHCs were less effective against MBL-producing Pseudomonas aeruginosa. Combination therapy with meropenem and SHCs successfully cured mice infected with IMP-1-producing E. coli and dually NDM-1/VIM-1-producing Klebsiella pneumoniae clinical isolates. X-ray crystallographic analyses revealed the inhibition mode of SHCs against MBLs; the sulfamoyl group of SHCs coordinated to two zinc ions, and the carboxylate group coordinated to one zinc ion and bound to positively charged amino acids Lys224/Arg228 conserved in MBLs. Preclinical testing revealed that the SHCs showed low toxicity in cell lines and mice and high stability in human liver microsomes. Our results indicate that SHCs are promising lead compounds for inhibitors of MBLs to combat MBL-producing CRE. IMPORTANCE Carbapenem antibiotics are the last resort for control of severe infectious diseases, bloodstream infections, and pneumonia caused by Gram-negative bacteria, including Enterobacteriaceae. However, carbapenem-resistant Enterobacteriaceae (CRE) strains have spread globally and are a critical concern in clinical settings because CRE infections are recognized as a leading cause of increased mortality among hospitalized patients. Most CRE produce certain kinds of serine carbapenemases (e.g., KPC- and GES-type β-lactamases) or metallo-β-lactamases (MBLs), which can hydrolyze carbapenems. Although effective MBL inhibitors are expected to restore carbapenem efficacy against MBL-producing CRE, no MBL inhibitor is currently clinically available. Here, we synthesized 2,5-diethyl-1-methyl-4-sulfamoylpyrrole-3-carboxylic acid (SPC), which is a potent inhibitor of MBLs. SPC is a remarkable lead compound for clinically useful MBL inhibitors and can potentially provide a considerable benefit to patients receiving treatment for lethal infectious diseases caused by MBL-producing CRE.

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Accumulation of Antibiotic Resistance Genes in Carbapenem-Resistant Acinetobacter baumannii Isolates Belonging to Lineage 2, Global Clone 1, from Outbreaks in 2012–2013 at a Tehran Burns Hospital

mSphere ◽

10.1128/msphere.00164-20 ◽

2020 ◽

Vol 5 (2) ◽

Cited By ~ 2

Author(s):

Masoumeh Douraghi ◽

Johanna J. Kenyon ◽

Parisa Aris ◽

Mahla Asadian ◽

Sedighe Ghourchian ◽

...

Keyword(s):

Middle East ◽

Acinetobacter Baumannii ◽

Resistance Genes ◽

Carbapenem Resistance ◽

Antibiotic Resistant ◽

Content Type ◽

Carbapenem Resistant ◽

East Region ◽

Lineage 2 ◽

Middle East Region

ABSTRACT The worldwide distribution of carbapenem-resistant Acinetobacter baumannii (CRAB) has become a global concern, particularly in countries where antibiotic prescription is not tightly regulated. However, knowledge of the genomic aspects of CRAB from many parts of the world is still limited. Here, 50 carbapenem-resistant A. baumannii isolates recovered at a single hospital in Tehran, Iran, during several outbreaks in 2012 and 2013 were found to be resistant to multiple antibiotics. They were examined using PCR mapping and multilocus sequence typing (MLST). All Iranian strains belonged to sequence type 328 in the Institut Pasteur MLST scheme (ST328IP), a single-locus variant of ST81IP, and all Iranian strains contained two carbapenem resistance genes, oxa23 and oxa24. The oxa23 gene is in the transposon Tn2006 in AbaR4, which interrupts the chromosomal comM gene. Phylogenetic analysis using whole-genome sequence (WGS) data for 9 isolates showed that they belonged to the same clade, designated the ST81/ST328 clade, within lineage 2 of global clone 1 (GC1). However, there were two groups that included either KL13 or KL18 at the K locus (KL) for capsular polysaccharide synthesis and either a tet39 or an aadB resistance gene, respectively. The genetic context of the resistance genes was determined, and the oxa24 (OXA-72 variant) and tet39 (tetracycline resistance) genes were each in a pdif module in different plasmids. The aadB gene cassette (which encodes gentamicin, kanamycin, and tobramycin resistance) was harbored by pRAY*, and the aphA6 gene (which encodes amikacin resistance) and sul2 gene (which encodes sulfamethoxazole resistance) were each harbored by a different plasmid. The sequences obtained here will underpin future studies of GC1 CRAB strains from the Middle East region. IMPORTANCE Carbapenem-resistant Acinetobacter baumannii strains are among the most critical antibiotic-resistant bacteria causing hospital-acquired infections and treatment failures. The global spread of two clones has been responsible for the bulk of the resistance, in particular, carbapenem resistance. However, there is a substantial gap in our knowledge of which clones and which specific lineages within each clone are circulating in many parts of the world, including Africa and the Middle East region. This is the first genomic analysis of carbapenem-resistant A. baumannii strains from Iran. All the isolates, from a single hospital, belonged to lineage 2 of global clone 1 (GC1) but fell into two groups distinguished by genes in the locus for capsule biosynthesis. The analysis suggests a potential origin of multiply antibiotic-resistant lineage 2 in the Middle East region and highlights the ongoing evolution of carbapenem-resistant GC1 A. baumannii strains. It will enhance future studies on the local and global GC1 population structure.

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Molecular Epidemiology of Emerging Carbapenem Resistance inAcinetobacter nosocomialisandAcinetobacter pittiiin Taiwan, 2010 to 2014

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02007-18 ◽

2019 ◽

Vol 63 (4) ◽

Cited By ~ 6

Author(s):

Feng-Jui Chen ◽

Wei-Cheng Huang ◽

Yu-Chieh Liao ◽

Hui-Ying Wang ◽

Jui-Fen Lai ◽

...

Keyword(s):

Molecular Epidemiology ◽

Species Identification ◽

Carbapenem Resistance ◽

Close Monitoring ◽

Aminoglycoside Resistance ◽

Content Type ◽

Carbapenem Resistant ◽

Acinetobacter Pittii ◽

Aminoglycoside Resistance Genes ◽

Genetic Structures

ABSTRACTThis study investigated the molecular epidemiology of carbapenem-resistantAcinetobacter nosocomialisandAcinetobacter pittii(ANAP). Clinical isolates ofAcinetobacterspp. collected by the biennial nationwide Taiwan Surveillance of Antimicrobial Resistance program from 2010 to 2014 were subjected to species identification, antimicrobial susceptibility testing, and PCR for detection of carbapenemase genes. Whole-genome sequencing or PCR mapping was performed to study the genetic surroundings of the carbapenemase genes. Among 1,041Acinetobacterisolates, the proportion of ANAP increased from 11% in 2010 to 22% in 2014. The rate of carbapenem resistance in these isolates increased from 7.5% (3/40) to 22% (14/64), with a concomitant increase in their resistance to other antibiotics. TheblaOXA-72andblaOXA-58genes were highly prevalent in carbapenem-resistant ANAP. Various genetic structures were found upstream ofblaOXA-58in different plasmids. Among the plasmids found to containblaOXA-72flanked by XerC/XerD, pAB-NCGM253-like was identified in 8 of 10 isolates. Conjugations of plasmids carryingblaOXA-72orblaOXA-58toA. baumanniiwere successful. In addition, three isolates with chromosome-locatedblaOXA-23embedded in AbGRI1-type structure with disruption of genes other thancomMwere detected. Two highly similar plasmids carrying class I integron containingblaIMP-1and aminoglycoside resistance genes were also found. The universal presence ofblaOXA-272/213-likeonA. pittiichromosomes and their lack of contribution to carbapenem resistance indicate its potential to be a marker for species identification. The increase of ANAP, along with their diverse mechanisms of carbapenem resistance, may herald their further spread and warrants close monitoring.

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