scholarly journals Emergence of a Multidrug-Resistant Enterobacter hormaechei Clinical Isolate from Egypt Co-Harboring mcr-9 and blaVIM-4

2020 ◽  
Vol 8 (4) ◽  
pp. 595 ◽  
Author(s):  
Ahmed M. Soliman ◽  
Fumito Maruyama ◽  
Hoda O. Zarad ◽  
Atsushi Ota ◽  
Hirofumi Nariya ◽  
...  
Keyword(s):  
Clinical Isolate ◽  
Susceptibility Testing ◽  
Genomic Sequence ◽  
Regulatory System ◽  
Multidrug Resistant ◽  
Colistin Resistance ◽  
Pcr Screening ◽  
Full Genomic Sequence ◽  
Enterobacter Hormaechei ◽  
Genetic Context

This study describes the first full genomic sequence of an mcr-9 and blaVIM-4-carrying multidrug-resistant Enterobacter hormaechei clinical isolate from Egypt. The strain was isolated in April 2015 from the sputum of a patient in Cairo, Egypt. The mcr-9 and blaVIM-4 genes were identified by PCR screening and DNA sequencing; the isolate was subjected to antimicrobial susceptibility testing, conjugation experiments, and whole genomic sequencing. mcr-9 and blaVIM-4 were carried by an IncHI2 plasmid, pAMS-38a (281,121 bp in size); the plasmid also carried genes conferring resistance against sulfonamides (sul1), quinolones (qnrA1), trimethoprim (dfrA1), β-lactams (blaTEM-1B), aminoglycosides (aac (6’)-II, aadA23, aadA2b, and ant(2’’)-Ia). The strain was susceptible to colistin (MIC, <0.25 μg/mL); this could be due to the absence of the qseC/qseB regulatory system located downstream of mcr-9 in Enterobacterales, which is involved in the induction of colistin-resistance. The genetic context of mcr-9 and blaVIM-4 was identified as IS1-mcr-9-IS903-pcoS-∆pcoE-rcnA and intI1-blaVIM-4—aac (6’)-II-dfrA1-∆aadA23-smr-ISPa21-qacE∆1, respectively. This is the first report of an mcr-9 and blaVIM-4 /IncHI2-carrying multidrug-resistant E. hormaechei clinical isolate from Africa and the Middle East. Plasmids of the IncHI2 group and the two insertion sequences (IS1, and IS903) might be the main vehicles for dissemination of mcr-9. Further screening for mcr-9 is essential for identifying its incidence and to prevent its dissemination.

scholarly journals An Improved Medium for Colistin Susceptibility Testing

2018 ◽  
Vol 56 (5) ◽  
Author(s):  
Konrad Gwozdzinski ◽  
Saina Azarderakhsh ◽  
Can Imirzalioglu ◽  
Linda Falgenhauer ◽  
Trinad Chakraborty
Keyword(s):  
Susceptibility Testing ◽  
Acquired Resistance ◽  
Multidrug Resistant ◽  
Colistin Resistance ◽  
Reliable Determination ◽  
Content Type ◽  
E Coli ◽  
Resistant Species ◽  
Mueller Hinton ◽  
Serovar Typhimurium

ABSTRACTThe plasmid-located colistin resistance genemcr-1confers low-level resistance to colistin, a last-line antibiotic against multidrug-resistant Gram-negative bacteria. Current CLSI-EUCAST recommendations require the use of a broth microdilution (BMD) method with cation-adjusted Mueller-Hinton (CA-MH) medium for colistin susceptibility testing, but approximately 15% of all MCR-1 producers are classified as sensitive in that broth. Here we report on an improved calcium-enhanced Mueller-Hinton (CE-MH) medium that permits simple and reliable determination ofmcr-1-containingEnterobacteriaceae. Colistin susceptibility testing was performed for 50mcr-1-containingEscherichia coliandKlebsiella pneumoniaeisolates, 7 intrinsically polymyxin-resistant species,K. pneumoniaeandE. coliisolates with acquired resistance to polymyxins due tomgrBandpmrBmutations, respectively, and 32mcr-1-negative, colistin-susceptible isolates ofAcinetobacter baumannii,Citrobacter freundii,Enterobacter cloacae,E. coli,K. pneumoniae, andSalmonella entericaserovar Typhimurium. A comparison of the colistin MICs determined in CA-MH medium and those obtained in CE-MH medium was performed using both the BMD and strip-based susceptibility test formats. We validated the data using an isogenic IncX4 plasmid lackingmcr-1. Use of the CE-MH broth provides clear separation between resistant and susceptible isolates in both BMD and gradient diffusion assays; this is true for bothmcr-1-containingEnterobacteriaceaeisolates and those exhibiting either intrinsic or acquired colistin resistance. CE-MH medium is simple to prepare and overcomes current problems associated with BMD and strip-based colistin susceptibility testing, and use of the medium is easy to implement in routine diagnostic laboratories, even in resource-poor settings.

scholarly journals Colistin heteroresistance and the involvement of the PmrAB regulatory system in Acinetobacter baumannii

2018 ◽  
Author(s):  
Yannick Charretier ◽  
Seydina M. Diene ◽  
Damien Baud ◽  
Sonia Chatellier ◽  
Emmanuelle Santiago-Allexant ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Population Analysis ◽  
Regulatory System ◽  
Clinical Problem ◽  
Multidrug Resistant ◽  
Regulatory Pathway ◽  
Colistin Resistance ◽  
Bacterial Killing ◽  
One Step

AbstractMultidrug-resistant Acinetobacter baumannii infection has recently emerged as a worldwide clinical problem and colistin is increasingly being used as last resort therapy. Despite its favorable bacterial killing, resistance and heteroresistance to colistin have been described. Mutations in the PmrAB regulatory pathway have been already associated with colistin resistance whereas the mechanisms for heteroresistance remain largely unknown. The purpose of the present study is to investigate the role of PmrAB in laboratory-selected mutants representative of global epidemic strains. During brief colistin exposure, colistin resistant and colistin heteroresistant mutants were selected in a one-step strategy. Population Analysis Profiling (PAP) was performed to confirm the suspected phenotype. Upon withdrawal of selective pressure, compensatory mutations were evaluated in another one-step strategy. A trans-complementation assay was designed to delineate the involvement of the PmrAB regulatory system using qPCR and PAP. Mutations in the PmrAB regulatory pathway were associated with colistin resistance and colistin heteroresistance as well. The transcomplementation assay provides a proof for the role played by changes in the PmrAB regulatory pathway. The level of colistin resistance is correlated to the level of expression of pmrC. The resistance phenotype was partially restored since the complemented strain became heteroresistant. This report shows the role of different mutations in the PmrAB regulatory pathway and warns on the development of colistin heteroresistance that could be present but not easily detected with routine testing.

scholarly journals Draft Genome Sequence of Pseudomonas aeruginosa Strain BWH047, a Sequence Type 235 Multidrug-Resistant Clinical Isolate Expressing High Levels of Colistin Resistance

2019 ◽  
Vol 8 (29) ◽  
Author(s):  
Kelly E. R. Bachta ◽  
Egon A. Ozer ◽  
Alisha Pandit ◽  
Francisco M. Marty ◽  
John J. Mekalanos ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Clinical Isolate ◽  
Genome Sequence ◽  
Draft Genome ◽  
Multidrug Resistant ◽  
Sequence Type ◽  
Draft Genome Sequence ◽  
Colistin Resistance ◽  
Content Type ◽  
Global Epidemic

The Gram-negative bacterium Pseudomonas aeruginosa is often multidrug resistant, associated with global epidemic outbreaks, and responsible for significant morbidity and mortality in hospitalized patients. Here, we present the draft genome sequence of BWH047, a multidrug-resistant P. aeruginosa clinical isolate belonging to the epidemic sequence type 235 and demonstrating high levels of colistin resistance.

scholarly journals Tigecycline susceptibility of multidrug-resistant Acinetobacter baumannii from intensive care units in the western Balkans

2020 ◽  
Vol 67 (3) ◽  
pp. 176-181
Author(s):  
Ina Gajic ◽  
Lazar Ranin ◽  
Dusan Kekic ◽  
Natasa Opavski ◽  
Aleksandra Smitran ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Susceptibility Testing ◽  
Multidrug Resistant ◽  
Inappropriate Therapy ◽  
Antibiotic Susceptibility Testing ◽  
Broth Microdilution ◽  
Western Balkans ◽  
Colistin Resistance ◽  
European Committee ◽  
Carbapenem Resistant

AbstractTigecycline can be effective to treat infections of carbapenem-resistant Acinetobacter baumannii (CRAB) however, no interpretive criteria have been approved so far. The objectives of this study were to evaluate the proportion of CRAB isolates and to compare gradient test with a broth microdilution (BMD) method for tigecycline susceptibility testing of A. baumannii.This study included 349 multidrug-resistant (MDR) Acinetobacter spp. collected from Serbia, Montenegro, Bosnia and Herzegovina in 2016 and 2017. Antibiotic susceptibility testing was performed by disk diffusion, VITEK2, gradient, ComASP Colistin. Tigecycline susceptibilities were interpreted according to breakpoints of European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Food and Drug Administration (FDA).Majority of the tested isolates were CRAB (92.8%). Tigecycline MIC50/MIC90 values were 4/8 μg/mL by BMD and 0.5/4 μg/mL by gradient test. Essential agreement for BMD and gradient test amounted to 65.1%. With EUCAST breakpoints, categorical agreement (CA) was achieved in 38% isolates. Major discordance (MD-false susceptibility/resistance) and minor discordance (mD-false categorization involving intermediate results) were observed in 10% and 57% A. baumannii, respectively. With FDA breakpoints, CA, MD and mD were observed in 44%, 16% and 47% isolates, respectively. Colistin resistance was 2.1%.The study highlights a high proportion of CRAB and several discordances between BMD and gradient test which may lead to inappropriate therapy.

scholarly journals MgrB Inactivation Is Responsible for Acquired Resistance to Colistin in Enterobacter hormaechei subsp. steigerwaltii

2020 ◽  
Vol 64 (6) ◽  
Author(s):  
Amel Mhaya ◽  
Dominique Bégu ◽  
Slim Tounsi ◽  
Corinne Arpin
Keyword(s):  
Acquired Resistance ◽  
Regulatory System ◽  
Multidrug Resistant ◽  
Negative Regulator ◽  
Clinical Strain ◽  
Sequencing Analysis ◽  
Content Type ◽  
Health Care Associated Infections ◽  
Enterobacter Hormaechei

ABSTRACT Multidrug-resistant strains belonging to the Enterobacter cloacae complex (ECC) group, and especially those belonging to clusters C-III, C-IV, and C-VIII, have increasingly emerged as a leading cause of health care-associated infections, with colistin used as one of the last lines of treatment. However, colistin-resistant ECC strains have emerged. The aim of this study was to prove that MgrB, the negative regulator of the PhoP/PhoQ two-component regulatory system, is involved in colistin resistance in ECC of cluster C-VIII, formerly referred to as Enterobacter hormaechei subsp. steigerwaltii. An in vitro mutant (Eh22-Mut) was selected from a clinical isolate of Eh22. The sequencing analysis of its mgrB gene showed the presence of one nucleotide deletion leading to the formation of a truncated protein of six instead of 47 amino acids. The wild-type mgrB gene from Eh22 and that of a clinical strain of Klebsiella pneumoniae used as controls were cloned, and the corresponding recombinant plasmids were used for complementation assays. The results showed a fully restored susceptibility to colistin and confirmed for the first time that mgrB gene expression plays a key role in acquired resistance to colistin in ECC strains.

Evaluation of the rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test for rapid colistin resistance detection in lactose non-fermenting Gram-negative bacteria

2021 ◽  
Vol 70 (6) ◽  
Author(s):  
Hyunsul Jung ◽  
Johann D. D. Pitout ◽  
Barend C. Mitton ◽  
Kathy-Anne Strydom ◽  
Chanel Kingsburgh ◽  
...  
Keyword(s):  
Type Species ◽  
Susceptibility Testing ◽  
Multidrug Resistant ◽  
Gram Negative Bacteria ◽  
Major Error ◽  
Colistin Resistance ◽  
Gram Negative ◽  
Content Type ◽  
Link Type ◽  
Extensively Drug Resistant

Introduction. Colistin is one of the last-resort antibiotics for treating multidrug-resistant (MDR) or extensively drug-resistant (XDR) lactose non-fermenting Gram-negative bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannii . Gap Statement. As the rate of colistin resistance is steadily rising, there is a need for rapid and accurate antimicrobial susceptibility testing methods for colistin. The Rapid ResaPolymyxin Acinetobacter / Pseudomonas NP test has recently been developed for rapid detection of colistin resistance in P. aeruginosa and A. baumannii . Aim. The present study aimed to evaluate the performance of the Rapid ResaPolymyxin Acinetobacter / Pseudomonas NP test in comparison with the reference broth microdilution (BMD) method. Methodology. The Rapid ResaPolymyxin Acinetobacter / Pseudomonas NP test was performed using a total of 135 P . aeruginosa (17 colistin-resistant and 118 colistin-susceptible) and 66 A. baumannii isolates (32 colistin-resistant and 34 colistin-susceptible), in comparison with the reference BMD method. Results. The categorical agreement of the Rapid ResaPolymyxin Acinetobacter / Pseudomonas NP test with the reference BMD method was 97.5 % with a major error rate of 0 % (0/152) and a very major error (VME) rate of 10.2 %. The VME rate was higher (23.5 %) when calculated separately for P. aeruginosa isolates. The overall sensitivity and specificity were 89.8 and 100 %, respectively. Conclusion. The Rapid ResaPolymyxin Acinetobacter / Pseudomonas NP test performed better for A. baumannii than for P. aeruginosa .

scholarly journals Draft Genome Assemblies of Clinical Isolates of Klebsiella pneumoniae V9011662 and Enterobacter hormaechei Entb306

2019 ◽  
Vol 8 (15) ◽  
Author(s):  
Lucas B. Harrison ◽  
Anna Selmecki ◽  
Nancy D. Hanson
Keyword(s):  
Antibiotic Resistance ◽  
Klebsiella Pneumoniae ◽  
Clinical Isolate ◽  
Draft Genome ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Content Type ◽  
Enterobacter Hormaechei ◽  
Genome Assemblies

Enterobacter hormaechei and Klebsiella pneumoniae are pathogenic Enterobacteriaceae that have been associated with the spread of antibiotic resistance. Here, we report draft genome assemblies of an Enterobacter hormaechei clinical isolate and a multidrug-resistant clinical isolate of Klebsiella pneumoniae.

scholarly journals BKC-2, a New BKC Variant Detected in MCR-9.1-producing Enterobacter hormaechei subsp. xiangfangensis

2020 ◽  
pp. AAC.01193-20
Author(s):  
Willames M. B. S. Martins ◽  
Evelin R. Martins ◽  
Letícia K. de Andrade ◽  
Refath Farzana ◽  
Timothy R. Walsh ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Resistance Gene ◽  
Resistance Genes ◽  
Tertiary Hospital ◽  
Multidrug Resistant ◽  
Colistin Resistance ◽  
Antimicrobial Resistance Genes ◽  
Genomic Characterization ◽  
Enterobacter Hormaechei

We performed the characterization of a multidrug-resistant (MDR) Enterobacter spp. isolate highlighting the genetic aspects of the antimicrobial resistance genes. An Enterobacter spp. isolate (Ec61) was recovered in 2014 from a transtracheal aspirate sample from a patient admitted to a Brazilian tertiary hospital and submitted to further microbiological and genomic characterization. Ec61 was identified as Enterobacter hormaechei subsp. xiangfangensis ST451, showed a MDR profile and the presence of genes codifying new β-lactamase variants, BKC-2 and ACT-84, and the mobile colistin resistance gene mcr-9.1.

scholarly journals Phosphoethanolamine Modification of Lipid A in Colistin-Resistant Variants of Acinetobacter baumannii Mediated by the pmrAB Two-Component Regulatory System

2011 ◽  
Vol 55 (7) ◽  
pp. 3370-3379 ◽  
Author(s):  
Alejandro Beceiro ◽  
Enrique Llobet ◽  
Jesús Aranda ◽  
José Antonio Bengoechea ◽  
Michel Doumith ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Clinical Isolate ◽  
Lipid A ◽  
Gene Knockout ◽  
Regulatory System ◽  
Clinical Isolates ◽  
Strain Atcc ◽  
Colistin Resistance ◽  
Content Type ◽  
Knockout Mutants

ABSTRACTColistin resistance is rare inAcinetobacter baumannii, and little is known about its mechanism. We investigated the role of PmrCAB in this trait, using (i) resistant and susceptible clinical strains, (ii) laboratory-selected mutants of the type strain ATCC 19606 and of the clinical isolate ABRIM, and (iii) a susceptible/resistant pair of isogenic clinical isolates, Ab15/133 and Ab15/132, isolated from the same patient.pmrABsequences in all the colistin-susceptible isolates were identical to reference sequences, whereas resistant clinical isolates harbored one or two amino acid replacements variously located in PmrB. Single substitutions in PmrB were also found in resistant mutants of strains ATCC 19606 and ABRIM and in the resistant clinical isolate Ab15/132. No mutations in PmrA or PmrC were found. Reverse transcriptase (RT)-PCR identified increased expression ofpmrA(4- to 13-fold),pmrB(2- to 7-fold), andpmrC(1- to 3-fold) in resistant versus susceptible organisms. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry showed the addition of phosphoethanolamine to the hepta-acylated form of lipid A in the resistant variants and in strain ATCC 19606 grown under low-Mg2+induction conditions.pmrBgene knockout mutants of the colistin-resistant ATCC 19606 derivative showed >100-fold increased susceptibility to colistin and 5-fold decreased expression ofpmrC; they also lacked the addition of phosphoethanolamine to lipid A. We conclude that the development of a moderate level of colistin resistance inA. baumanniirequires distinct genetic events, including (i) at least one point mutation inpmrB, (ii) upregulation ofpmrAB, and (iii) expression ofpmrC, which lead to addition of phosphoethanolamine to lipid A.

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