scholarly journals Increasing Resistance to Azithromycin inNeisseria gonorrhoeaein Eastern Chinese Cities: Resistance Mechanisms and Genetic Diversity among Isolates from Nanjing

2018 ◽  
Vol 62 (5) ◽  
Author(s):  
Chuan Wan ◽  
Yang Li ◽  
Wen-Jing Le ◽  
Yu-Rong Liu ◽  
Sai Li ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Resistance Mechanisms ◽  
23S Rrna ◽  
Molecular Characteristics ◽  
Chinese Cities ◽  
Content Type ◽  
Public Health Challenge ◽  
High Level ◽  
Level Resistance

ABSTRACTAzithromycin resistance (AZM-R) ofNeisseria gonorrhoeaeis emerging as a clinical and public health challenge. We determined molecular characteristics of recent AZM-R Nanjing gonococcal isolates and tracked the emergence of AZM-R isolates in eastern Chinese cities in recent years. A total of 384N. gonorrhoeaeisolates from Nanjing collected from 2013 to 2014 were tested for susceptibility to AZM and six additional antibiotics; all AZM-R strains were characterized genetically for resistance determinants by sequencing and were genotyped usingN. gonorrhoeaemultiantigen sequence typing (NG-MAST). Among the 384 isolates, 124 (32.3%) were AZM-R. High-level resistance (MIC, ≥256 mg/liter) was present in 10.4% (40/384) of isolates, all of which possessed the A2143G mutation in all four 23S rRNA alleles. Low- to mid-level resistance (MIC, 1 to 64 mg/liter) was present in 21.9% (84/384) of isolates, 59.5% of which possessed the C2599T mutation in all four 23S rRNA alleles. The 124 AZM-R isolates were distributed in 71 different NG-MAST sequence types (STs). ST1866 was the most prevalent type in high-level AZM-R (HL-AZM-R) isolates (45% [18/40]). This study, together with previous reports, revealed that the prevalence of AZM-R inN. gonorrhoeaeisolates in certain eastern Chinese cities has risen >4-fold (7% to 32%) from 2008 to 2014. The principal mechanisms of AZM resistance in recent Nanjing isolates were A2143G mutations (high-level resistance) and C2599T mutations (low- to mid-level resistance) in the 23S rRNA alleles. Characterization of NG-MAST STs and phylogenetic analysis indicated the genetic diversity ofN. gonorrhoeaein Nanjing; however, ST1866 was the dominant genotype associated with HL-AZM-R isolates.

scholarly journals Ribosomal Mutations Conferring Macrolide Resistance in Legionella pneumophila

2017 ◽  
Vol 61 (3) ◽  
Author(s):  
Ghislaine Descours ◽  
Christophe Ginevra ◽  
Nathalie Jacotin ◽  
Françoise Forey ◽  
Joëlle Chastang ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Ribosomal Proteins ◽  
Fold Increase ◽  
Resistance Mechanisms ◽  
Macrolide Resistance ◽  
23S Rrna ◽  
Content Type ◽  
First Line Therapy ◽  
High Level ◽  
Domain V

ABSTRACT Monitoring the emergence of antibiotic resistance is a recent issue in the treatment of Legionnaires' disease. Macrolides are recommended as first-line therapy, but resistance mechanisms have not been studied in Legionella species. Our aim was to determine the molecular basis of macrolide resistance in L. pneumophila. Twelve independent lineages from a common susceptible L. pneumophila ancestral strain were propagated under conditions of erythromycin or azithromycin pressure to produce high-level macrolide resistance. Whole-genome sequencing was performed on 12 selected clones, and we investigated mutations common to all lineages. We reconstructed the dynamics of mutation for each lineage and demonstrated their involvement in decreased susceptibility to macrolides. The resistant mutants were produced in a limited number of passages to obtain a 4,096-fold increase in erythromycin MICs. Mutations affected highly conserved 5-amino-acid regions of L4 and L22 ribosomal proteins and of domain V of 23S rRNA (G2057, A2058, A2059, and C2611 nucleotides). The early mechanisms mainly affected L4 and L22 proteins and induced a 32-fold increase in the MICs of the selector drug. Additional mutations related to 23S rRNA mostly occurred later and were responsible for a major increase of macrolide MICs, depending on the mutated nucleotide, the substitution, and the number of mutated genes among the three rrl copies. The major mechanisms of the decreased susceptibility to macrolides in L. pneumophila and their dynamics were determined. The results showed that macrolide resistance could be easily selected in L. pneumophila and warrant further investigations in both clinical and environmental settings.

scholarly journals Prevalence and molecular characterization of methicillin-resistant Staphylococcus aureus with mupirocin, fusidic acid and/or retapamulin resistance

2020 ◽  
Author(s):  
Wenjing Chen ◽  
Chunyan He ◽  
Han Yang ◽  
Wen Shu ◽  
Zelin Cui ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Fusidic Acid ◽  
Resistance Mechanisms ◽  
Antibiotics Resistance ◽  
Genetic Characteristics ◽  
Methicillin Resistant ◽  
Low Level ◽  
High Level ◽  
Level Resistance

Abstract Data on the prevalence of resistance to mupirocin (MUP), fusidic acid (FA) and retapamulin (RET) in methicillin-resistant Staphylococcus aureus (MRSA) from China are still limited. In this study we examined these three antibiotics resistance pheno and geno-typically in 1206 MRSA clinical isolates. Phenotypic MUP, FA and RET resistance was determined by MICs, and genotypically by PCR and DNA sequencing examining genes mupA / B , fusB - D , cfr and vgaA / Av , and mutations in ileS , fusA / E , rplC , and 23S RNA V domain. The genetic characteristics of resistance isolates were conducted by PFGE and MLST. Overall MRSA MUP, FA and RET resistance was low (5.1%, 1.0% and 0.3%, respectively). The mupA was the mechanism of high-level MUP resistance. All low-level MUP resistance isolates possessed an equivocal mutation N213D in IleS, and 2 of them additionally had the reported V588F mutation impacting the Rossman fold. FusA mutations, such as L461K, H457Q, H457Y and V90I, were the primary FA resistance mechanisms among high-level resistance isolates, most of which contained fusC ; however, all low-level resistance strains carried fusB . No resistance mechanisms detected were found among RET resistance isolates. Genetic analysis demonstrated clone spread for MUP resistance isolates. In conclusion, MUP, FA and RET exhibited highly activity against MRSA isolates. Acquired genes and chromosome-borne genes mutations were responsible for MUP and FA resistance, and further investigation is needed to uncover the RET resistance mechanisms. Moreover, the surveillance to MUP in MRSA should be strengthened to prevent resistance increase due to the expansion of clones.

scholarly journals Characterization of an Enterococcus gallinarum Isolate Carrying a DualvanAandvanBCassette

2015 ◽  
Vol 53 (7) ◽  
pp. 2225-2229 ◽  
Author(s):  
Alireza Eshaghi ◽  
Dea Shahinas ◽  
Aimin Li ◽  
Ruwandi Kariyawasam ◽  
Philip Banh ◽  
...  
Keyword(s):  
Clinical Isolate ◽  
Resistance Mechanism ◽  
Vancomycin Resistance ◽  
Content Type ◽  
Enterococcal Species ◽  
Enterococcus Gallinarum ◽  
High Level ◽  
Identification And Characterization ◽  
Level Resistance

The ability of vancomycin resistance determinants to be horizontally transferred within enterococci species is a concern. Identification and characterization of vancomycin-resistant enterococci (VRE) in a clinical isolate have a significant impact on infection control practices. In this study, we describe a clinical isolate ofEnterococcus gallinarumexhibiting high-level resistance to vancomycin and teicoplanin. The genetic characterization of this isolate showed the presence ofvanAandvanBgenes in addition to the naturally carriedvanCgene.vanAwas identified on pA6981, a 35,608-bp circular plasmid with significant homology to plasmid pS177. ThevanBoperon was integrated into the bacterial chromosome and showed a high level of homology to previously reported Tn1549and Tn5382. To the best of our knowledge, this is the first report ofE. gallinarumcarrying bothvanAandvanBoperons, indicating the importance of identifying the vancomycin resistance mechanism in non-E. faeciumand non-E. faecalisenterococcal species.

scholarly journals Is Neisseria gonorrhoeae Initiating a Future Era of Untreatable Gonorrhea?: Detailed Characterization of the First Strain with High-Level Resistance to Ceftriaxone

2011 ◽  
Vol 55 (7) ◽  
pp. 3538-3545 ◽  
Author(s):  
Makoto Ohnishi ◽  
Daniel Golparian ◽  
Ken Shimuta ◽  
Takeshi Saika ◽  
Shinji Hoshina ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Resistance Mechanisms ◽  
New Drugs ◽  
Public Health Response ◽  
Detailed Characterization ◽  
Content Type ◽  
Resistance Determinants ◽  
Confirmatory Tests ◽  
High Level

ABSTRACTRecently, the firstNeisseria gonorrhoeaestrain (H041) that is highly resistant to the extended-spectrum cephalosporin (ESC) ceftriaxone, the last remaining option for empirical first-line treatment, was isolated. We performed a detailed characterization of H041, phenotypically and genetically, to confirm the finding, examine its antimicrobial resistance (AMR), and elucidate the resistance mechanisms. H041 was examined using seven species-confirmatory tests, antibiograms (30 antimicrobials),porBsequencing,N. gonorrhoeaemultiantigen sequence typing (NG-MAST), multilocus sequence typing (MLST), and sequencing of ESC resistance determinants (penA,mtrR,penB,ponA, andpilQ). Transformation, using appropriate recipient strains, was performed to confirm the ESC resistance determinants. H041 was assigned to serovar Bpyust, MLST sequence type (ST) ST7363, and the new NG-MAST ST4220. H041 proved highly resistant to ceftriaxone (2 to 4 μg/ml, which is 4- to 8-fold higher than any previously described isolate) and all other cephalosporins, as well as most other antimicrobials tested. A newpenAmosaic allele caused the ceftriaxone resistance. In conclusion,N. gonorrhoeaehas now shown its ability to also develop ceftriaxone resistance. Although the biological fitness of ceftriaxone resistance inN. gonorrhoeaeremains unknown,N. gonorrhoeaemay soon become a true superbug, causing untreatable gonorrhea. A reduction in the global gonorrhea burden by enhanced disease control activities, combined with wider strategies for general AMR control and enhanced understanding of the mechanisms of emergence and spread of AMR, which need to be monitored globally, and public health response plans for global (and national) perspectives are important. Ultimately, the development of new drugs for efficacious gonorrhea treatment is necessary.

scholarly journals Emergence and Spread of Neisseria gonorrhoeae Strains with High-Level Resistance to Azithromycin in Taiwan from 2001 to 2018

2019 ◽  
Vol 63 (9) ◽  
Author(s):  
Yen-Hung Liu ◽  
Ya-Hui Wang ◽  
Chun-Hsing Liao ◽  
Po-Ren Hsueh
Keyword(s):  
Neisseria Gonorrhoeae ◽  
23S Rrna ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Coding Region ◽  
Content Type ◽  
First Choice ◽  
Agar Dilution ◽  
High Level ◽  
Level Resistance

ABSTRACT A total of 598 Neisseria gonorrhoeae isolates obtained from patients in Taiwan from 2001 to 2018 were evaluated. The MICs of ceftriaxone (CRO) and azithromycin (AZM) against the isolates were determined by the agar dilution method. N. gonorrhoeae isolates with AZM MICs of ≥1 μg/ml were identified and characterized by the presence of AZM resistance determinants. For high-level AZM-resistant (AZM-HLR) isolates (MIC ≥ 256 μg/ml), genotyping was performed using multilocus sequence typing (MLST) and N. gonorrhoeae multiantigen sequence typing (NG-MAST). Among the N. gonorrhoeae isolates studied, 8.7% (52/598) exhibited AZM MICs of ≥1 μg/ml. Thirteen of the 52 isolates contained A2059G (23S rRNA NG-STAR type 1) or C2611T (23S rRNA NG-STAR type 2) mutations. The prevalence of the A2059G mutation was higher in AZM-HLR isolates (P < 0.001). The −35A deletion in the promoter region of the mtrR gene did not differ between AZM-HLR isolates (100%, 10/10) and the isolates with AZM MICs of 1 μg/ml to 64 μg/ml (95.2%, 40/42) (P = 1.000). The presence of mutations in the mtrR coding region was significantly different between these two groups at 90% (9/10) and 26.2% (11/42), respectively (P < 0.001). The AZM-HLR isolates, all carrying four mutated A2059G alleles, a −35A deletion, and G45D, were classified as MLST 12039/10899 and NG-MAST 1866/16497. In conclusion, Taiwan is among the countries reporting gonococci with high-level resistance to AZM so that a single dose of 1 g ceftriaxone intramuscularly as the first choice for management of N. gonorrhoeae infection should be evaluated.

scholarly journals Genomic Epidemiology and Molecular Resistance Mechanisms of Azithromycin-Resistant Neisseria gonorrhoeae in Canada from 1997 to 2014

2016 ◽  
Vol 54 (5) ◽  
pp. 1304-1313 ◽  
Author(s):  
Walter Demczuk ◽  
Irene Martin ◽  
Shelley Peterson ◽  
Amrita Bharat ◽  
Gary Van Domselaar ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Resistance Mechanisms ◽  
23S Rrna ◽  
Phylogenomic Analysis ◽  
Single Nucleotide ◽  
Content Type ◽  
E Coli ◽  
Genomic Epidemiology ◽  
High Level ◽  
Promoter Mutations

The emergence ofNeisseria gonorrhoeaestrains with decreased susceptibility to cephalosporins and azithromycin (AZM) resistance (AZMr) represents a public health threat of untreatable gonorrhea infections. Genomic epidemiology through whole-genome sequencing was used to describe the emergence, dissemination, and spread of AZMrstrains. The genomes of 213 AZMrand 23 AZM-susceptibleN. gonorrhoeaeisolates collected in Canada from 1989 to 2014 were sequenced. Core single nucleotide polymorphism (SNP) phylogenomic analysis resolved 246 isolates into 13 lineages. High-level AZMr(MICs ≥ 256 μg/ml) was found in 5 phylogenetically diverse isolates, all of which possessed the A2059G mutation (Escherichia colinumbering) in all four 23S rRNA alleles. One isolate with high-level AZMrcollected in 2009 concurrently had decreased susceptibility to ceftriaxone (MIC = 0.125 μg/ml). An increase in the number of 23S rRNA alleles with the C2611T mutations (E. colinumbering) conferred low to moderate levels of AZMr(MICs = 2 to 4 and 8 to 32 μg/ml, respectively). Low-level AZMrwas also associated withmtrRpromoter mutations, including the −35A deletion and the presence ofNeisseria meningitidis-like sequences. Geographic and temporal phylogenetic clustering indicates that emergent AZMrstrains arise independently and can then rapidly expand clonally in a region through local sexual networks.

scholarly journals Characterization of FosL1, a Plasmid-Encoded Fosfomycin Resistance Protein Identified in Escherichia coli

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Nicolas Kieffer ◽  
Laurent Poirel ◽  
Marie-Christine Descombes ◽  
Patrice Nordmann
Keyword(s):  
Escherichia Coli ◽  
The United States ◽  
Amino Acid Identity ◽  
Resistance Mechanisms ◽  
Resistant Isolate ◽  
Content Type ◽  
Fosfomycin Resistance ◽  
High Level ◽  
Tract Infections

ABSTRACT Fosfomycin is gaining renewed interest for treating urinary tract infections. Monitoring fosfomycin resistance is therefore important in order to detect the emergence of novel resistance mechanisms. Here, we used the Rapid Fosfomycin NP test to screen a collection of extended-spectrum-β-lactamase-producing Escherichia coli isolates from Switzerland and found a fosfomycin-resistant isolate in which a novel plasmid-mediated fosfomycin resistance gene, named fosL1, was identified. The FosL1 protein is a putative glutathione S-transferase enzyme conferring high-level resistance to fosfomycin and sharing between 57% to 63% amino acid identity with other FosA-like family members. Genetic analyses showed that the fosL1 gene was embedded in a mobile insertion cassette and had likely been acquired by transposition through a Tn7-related mechanism. In silico analysis over GenBank databases identified the FosL1-encoding gene in addition to another variant (fosL1 and fosL2, respectively) in two Salmonella enterica isolates from the United States. Our study further highlights the necessity of monitoring fosfomycin resistance in Enterobacteriaceae to identify the emergence of novel mechanisms of resistance.

Molecular Characterization of Fluoroquinolone Resistance Mechanisms of Campylobacter Isolates from Duck Meats

2017 ◽  
Vol 80 (12) ◽  
pp. 2056-2059
Author(s):  
Min Kang ◽  
Bai Wei ◽  
Sung-Woon Choi ◽  
Se-Yeoun Cha ◽  
Hyung-Kwan Jang
Keyword(s):  
Nalidixic Acid ◽  
Efflux Pump ◽  
Resistance Mechanisms ◽  
Quinolone Resistance ◽  
Fluoroquinolone Resistance ◽  
Gyra Gene ◽  
Meat Samples ◽  
High Level ◽  
Level Resistance

ABSTRACT The purpose of this study was to identify the molecular basis of quinolone resistance of Campylobacter isolates recovered from duck meats. Sixty-one isolates from duck meat samples were studied using sequence analysis of the gyrA gene, and PCR assays were used to identify the presence of the CmeABC efflux pump and its restored sensitivity in the presence of efflux-pump inhibitors. High-level resistance to nalidixic acid and ciprofloxacin was attributed to amino acid substitutions Thr-86-Ile in some isolates. The PCR assay confirmed the presence of the cmeB gene in 29 (47.5%) of the 61 Campylobacter isolates. Phenylalanine arginine β-naphthylamide reduced the MICs of ciprofloxacin and nalidixic acid in 16 (55.2%) and 26 (89.7%) isolates, respectively. The Thr-86-Ile substitution in the gyrA was the primary contributor to the high-level quinolone resistance in Campylobacter isolates from duck meats.

scholarly journals Identification of a Novel Gene Associated with High-Level β-Lactam Resistance in Heterogeneous Vancomycin-IntermediateStaphylococcus aureusStrain Mu3 and Methicillin-ResistantS. aureusStrain N315

2018 ◽  
Vol 63 (2) ◽  
pp. e00712-18 ◽  
Author(s):  
Miki Matsuo ◽  
Norio Yamamoto ◽  
Tomomi Hishinuma ◽  
Keiichi Hiramatsu
Keyword(s):  
Genetic Interaction ◽  
Stringent Response ◽  
Resistance Mechanisms ◽  
Multicopy Plasmid ◽  
Content Type ◽  
Unknown Gene ◽  
Type Gene ◽  
High Level ◽  
Chromosomal Mutations ◽  
Level Resistance

ABSTRACTβ-Lactam resistance levels vary among methicillin-resistantStaphylococcus aureus(MRSA) clinical isolates, mediated by chromosomal mutations and exogenous resistance genemecA. However, MRSA resistance mechanisms are incompletely understood. A P440L mutation in the RNA polymerase β′ subunit (RpoC) in slow-vancomycin-intermediateS. aureus(sVISA) strain V6-5 is associated with conversion of heterogeneous VISA (hVISA) to sVISA. In this study, we found a V6-5-derivative strain (L4) with significantly decreased MICs to oxacillin (OX) and vancomycin. Whole-genome sequencing revealed that L4 has nonsense mutations in two genes,relQ, encoding (p)ppGpp synthetase, an alarmone of the stringent response, and a gene of unknown function.relQdeletion in the hVISA strain Mu3 did not affect OX MIC. However, introducing nonsense mutation of the unknown gene into Mu3 decreased OX MIC, whereas wild-type gene recovered high-level resistance. Thus, mutation of this unknown gene (ehoM) decreased β-lactam resistance in Mu3 and L4. Presence ofrelQin a multicopy plasmid restored high-level resistance in strain L4 but not in theehoMmutant Mu3 strain, indicating a genetic interaction betweenehoMandrelQdepending on the L4 genetic background. While mupirocin (a stringent response inducer) can increase the β-lactam resistance of MRSA, mupirocin supplementation in anehoMdeletion mutant of N315 did not elevate resistance.ehoMexpression in N315 was induced by mupirocin, and the relative amount ofehoMtranscript in Mu3 was higher than in N315 induced by the stringent response. Our findings indicate thatehoMplays an essential role in high-level β-lactam resistance in MRSA via the stringent response.

scholarly journals The epidemiology and molecular characteristics of linezolid-resistant Staphylococcus capitis in Huashan Hospital, Shanghai

2020 ◽  
Vol 69 (8) ◽  
pp. 1079-1088
Author(s):  
Li Ding ◽  
Pei Li ◽  
Yang Yang ◽  
Dongfang Lin ◽  
Xiaogang Xu
Keyword(s):  
Type Species ◽  
Resistance Mechanisms ◽  
23S Rrna ◽  
Molecular Characteristics ◽  
Genetic Characteristics ◽  
Content Type ◽  
Link Type ◽  
Staphylococcus Capitis ◽  
Broth Microdilution Method ◽  
V Region

Introduction. Linezolid-resistant (LZR) Staphylococcus capitis has recently emerged in our hospital, and its potential resistance mechanisms are still not clear. Aim. This study aimed to investigate the epidemiology, clinical and genetic characteristics, resistance mechanisms and biofilm formation capacity of LZR S. capiti s isolated from patients at Huashan Hospital, Shanghai, PR China between 2012 and 2018. Methodology. Strains were subjected to antimicrobial susceptibility testing (AST) with antibiotics using the broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The presence of cfr, optrA and poxtA, as well as mutations in the 23S ribosomal (r)RNA and ribosomal proteins, was investigated using PCR and sequencing techniques. The genetic relationship between isolates was analysed using pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS). Biofilm biomasses were detected by using crystal violet staining. Results. Twenty-one LZR S. capitis strains displayed MICs of 32–512 μg ml−1. All LZR strains showed G2576T and C2104T mutations in the 23S rRNA V region. Besides G2576T and C2104T, no base mutations were detected in the V region. The cfr was detected in 12 strains, while optrA and poxtA were not amplified in 21 S . capitis strains. PFGE showed that the LZR S. capitis strains belonged to a single clone. The phylogenetic tree showed that 20 LZR S. capitis strains were highly similar to LNZR-1, isolated from Harbin (located in the north of China) in 2013, which showed resistance to linezolid. Conclusions. In this research, cfr-negative strains displayed linezolid MICs of 32 μg ml−1. In comparison, cfr-positive strains exhibited linezolid MICs of 128–512 μg ml−1, indicating that high levels of linezolid resistance appear to be related to the presence of cfr. The outbreak of LZR S. capitis in our hospital needs to be monitored closely.

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