scholarly journals Disruption of an Enterococcus faecium Species-Specific Gene, a Homologue of Acquired Macrolide Resistance Genes of Staphylococci, Is Associated with an Increase in Macrolide Susceptibility

2001 ◽  
Vol 45 (1) ◽  
pp. 263-266 ◽  
Author(s):  
Kavindra V. Singh ◽  
Kumthorn Malathum ◽  
Barbara E. Murray
Keyword(s):  
Resistance Gene ◽  
Resistance Genes ◽  
Enterococcus Faecium ◽  
Complete Sequence ◽  
Macrolide Resistance ◽  
Specific Gene ◽  
Intrinsic Resistance ◽  
Macrolide Resistance Gene ◽  
Species Specific

ABSTRACT The complete sequence (1,479 nucleotides) of msrC, part of which was recently reported by others using a different strain, was determined. This gene was found in 233 of 233 isolates ofEnterococcus faecium but in none of 265 other enterococci. Disruption of msrC was associated with a two- to eightfold decrease in MICs of erythromycin azithromycin, tylosin, and quinupristin, suggesting that it may explain in part the apparent greater intrinsic resistance to macrolides of isolates of E. faecium relative to many streptococci. This endogenous, species-specific gene of E. faecium is 53% identical tomsr(A), suggesting that it may be a remote progenitor of the acquired macrolide resistance gene found in some isolates of staphylococci.

scholarly journals Novel Plasmid-Borne Multidrug Resistance Gene Cluster Includinglsa(E) from a Linezolid-Resistant Enterococcus faecium Isolate of Swine Origin

2015 ◽  
Vol 59 (11) ◽  
pp. 7113-7116 ◽  
Author(s):  
Hongbin Si ◽  
Wan-Jiang Zhang ◽  
Shengbo Chu ◽  
Xiu-Mei Wang ◽  
Lei Dai ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Gene Cluster ◽  
Resistance Gene ◽  
Resistance Genes ◽  
Enterococcus Faecium ◽  
Insertion Element ◽  
Multidrug Resistance Gene ◽  
Content Type ◽  
Recombination Processes ◽  
Faecium Isolate

ABSTRACTA novel nonconjugative plasmid of 28,489 bp from a porcine linezolid-resistantEnterococcus faeciumisolate was completely sequenced. This plasmid harbored a novel type of multiresistance gene cluster that comprised the resistance geneslnu(B),lsa(E),spw,aadE,aphA3, and two copies oferm(B), which account for resistance to macrolides, lincosamides, streptogramins, pleuromutilins, streptomycin, spectinomycin, and kanamycin/neomycin. Structural comparisons suggested that this plasmid might have developed from other enterococcal plasmids by insertion element (IS)-mediated interplasmid recombination processes.

scholarly journals Evaluation ofShigellaSpecies Azithromycin CLSI Epidemiological Cutoff Values and Macrolide Resistance Genes

2019 ◽  
Vol 57 (4) ◽  
Author(s):  
Muna Salah ◽  
Issa Shtayeh ◽  
Raed Ghneim ◽  
Randa Al-Qass ◽  
Ali Sabateen ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Diffusion Zone ◽  
Shigella Flexneri ◽  
Macrolide Resistance ◽  
Disk Diffusion ◽  
Content Type ◽  
Zone Diameter ◽  
Cutoff Values ◽  
Macrolide Resistance Gene ◽  
Content Support

ABSTRACTAzithromycin (AZM) has been recommended by the American Academy of Pediatrics for the treatment of shigellosis in children. In this study, 502Shigellaspecies isolated between 2004 and 2014 were tested for AZM epidemiological cutoff values (ECV) by disk diffusion. AZM MICs and the presence of the macrolide resistance genes [erm(A),erm(B),erm(C),ere(A),ere(B),mph(A),mph(B),mph(D),mef(A), andmsr(A)] were determined for all 56 (11.1%) isolates with an AZM disk diffusion zone diameter of ≤15 mm. The distribution of AZM ECV MICs was also determined for 186Shigellaisolates with a disk zone diameter of ≥16 mm. Finally, pulsed-field gel electrophoresis (PFGE) was performed on 15Shigella flexneriisolates with an AZM disk zone diameter of <16 mm from different years and geographic locations. Serotyping the 502Shigellaspecies isolates revealed that 373 (74%) wereS. sonnei, 119 (24%) wereS. flexneri,and 10 (2%) wereS. boydii. Of the 119Shigella flexneriisolates, 48 (42%) isolates had an AZM disk diffusion zone diameter of ≤15 mm and a MIC of ≥16 µg/ml. With the exception of one isolate, all were positive for the macrolide resistance genemph(A).S. flexneriPFGE showed four distinct patterns, with patterns I and II presenting with 92.3% genetic similarity. On the other hand, 2 (0.5%) of the 373S. sonneiisolates had the AZM non-wild-type (NWT) ECV phenotype (those with acquired or mutational resistance), as the AZM MICs were ≥32 µg/ml and the isolates were positive for themph(A) gene. Overall, ourS. flexneriresults are in concordance with the CLSI AZM ECV, but isolates with an AZM disk diffusion zone diameter between 14 and 15 mm should be carefully evaluated, as theS. flexneriAZM MIC for NWT isolates may need adjustment to 32 µg/ml. Our data onS. sonneisupport that the AZM NWT ECV should be 11 mm for the disk diffusion zone diameter and ≥32 µg/ml for the MICs.

scholarly journals Impact of Long-Term Erythromycin Therapy on the Oropharyngeal Microbiome and Resistance Gene Reservoir in Non-Cystic Fibrosis Bronchiectasis

mSphere ◽  
2018 ◽  
Vol 3 (2) ◽  
pp. e00103-18 ◽  
Author(s):  
Jocelyn M. Choo ◽  
Guy C. J. Abell ◽  
Rachel Thomson ◽  
Lucy Morgan ◽  
Grant Waterer ◽  
...  
Keyword(s):  
Resistance Gene ◽  
Quantitative Pcr ◽  
Resistance Genes ◽  
Low Dose ◽  
Controlled Trial ◽  
Macrolide Resistance ◽  
Microbiota Composition ◽  
Content Type ◽  
Commensal Microbiota

ABSTRACT Long-term macrolide therapy reduces rates of pulmonary exacerbation in bronchiectasis. However, little is known about the potential for macrolide therapy to alter the composition and function of the oropharyngeal commensal microbiota or to increase the carriage of transmissible antimicrobial resistance. We assessed the effect of long-term erythromycin on oropharyngeal microbiota composition and the carriage of transmissible macrolide resistance genes in 84 adults with bronchiectasis, enrolled in the Bronchiectasis and Low-dose Erythromycin Study (BLESS) 48-week placebo-controlled trial of twice-daily erythromycin ethylsuccinate (400 mg). Oropharyngeal microbiota composition and macrolide resistance gene carriage were determined by 16S rRNA gene amplicon sequencing and quantitative PCR, respectively. Long-term erythromycin treatment was associated with a significant increase in the relative abundance of oropharyngeal Haemophilus parainfluenzae (P = 0.041) and with significant decreases in the relative abundances of Streptococcus pseudopneumoniae (P = 0.024) and Actinomyces odontolyticus (P = 0.027). Validation of the sequencing results by quantitative PCR confirmed a significant decrease in the abundance of Actinomyces spp. (P = 0.046). Erythromycin treatment did not result in a significant increase in the number of subjects who carried erm(A), erm(B), erm(C), erm(F), mef(A/E), and msrA macrolide resistance genes. However, the abundance of erm(B) and mef(A/E) gene copies within carriers who had received erythromycin increased significantly (P < 0.05). Our findings indicate that changes in oropharyngeal microbiota composition resulting from long-term erythromycin treatment are modest and are limited to a discrete group of taxa. Associated increases in levels of transmissible antibiotic resistance genes within the oropharyngeal microbiota highlight the potential for this microbial system to act as a reservoir for resistance. IMPORTANCE Recent demonstrations that long-term macrolide therapy can prevent exacerbations in chronic airways diseases have led to a dramatic increase in their use. However, little is known about the wider, potentially adverse impacts of these treatments. Substantial disruption of the upper airway commensal microbiota might reduce its contribution to host defense and local immune regulation, while increases in macrolide resistance carriage would represent a serious public health concern. Using samples from a randomized controlled trial, we show that low-dose erythromycin given over 48 weeks influences the composition of the oropharyngeal commensal microbiota. We report that macrolide therapy is associated with significant changes in the relative abundances of members of the Actinomyces genus and with significant increases in the carriage of transmissible macrolide resistance. Determining the clinical significance of these changes, relative to treatment benefit, now represents a research priority.

scholarly journals Detection of Oxazolidinone Resistance Genes and Characterization of Genetic Environments in Enterococci of Swine Origin, Italy

2020 ◽  
Vol 8 (12) ◽  
pp. 2021
Author(s):  
Simona Fioriti ◽  
Gianluca Morroni ◽  
Sonia Nina Coccitto ◽  
Andrea Brenciani ◽  
Alberto Antonelli ◽  
...  
Keyword(s):  
Resistance Gene ◽  
Enterococcus Faecalis ◽  
Resistance Genes ◽  
Enterococcus Faecium ◽  
Central Italy ◽  
Great Variability ◽  
Linezolid Resistance ◽  
Pig Farms ◽  
Clonality Analysis

One hundred forty-five florfenicol-resistant enterococci, isolated from swine fecal samples collected from 76 pig farms, were investigated for the presence of optrA, cfr, and poxtA genes by PCR. Thirty florfenicol-resistant Enterococcus isolates had at least one linezolid resistance gene. optrA was found to be the most widespread linezolid resistance gene (23/30), while cfr and poxtA were detected in 6/30 and 7/30 enterococcal isolates, respectively. WGS analysis also showed the presence of the cfr(D) gene in Enterococcus faecalis (n = 2 isolates) and in Enterococcus avium (n = 1 isolate). The linezolid resistance genes hybridized both on chromosome and plasmids ranging from ~25 to ~240 kb. Twelve isolates were able to transfer linezolid resistance genes to enterococci recipient. WGS analysis displayed a great variability of optrA genetic contexts identical or related to transposons (Tn6628 and Tn6674), plasmids (pE035 and pWo27-9), and chromosomal regions. cfr environments showed identities with Tn6644-like transposon and a region from p12-2300 plasmid; cfr(D) genetic contexts were related to the corresponding region of the plasmid 4 of Enterococcus faecium E8014; poxtA was always found on Tn6657. Circular forms were obtained only for optrA- and poxtA-carrying genetic contexts. Clonality analysis revealed the presence of E. faecalis (ST16, ST27, ST476, and ST585) and E. faecium (ST21) clones previously isolated from humans. These results demonstrate a dissemination of linezolid resistance genes in enterococci of swine origin in Central Italy and confirm the spread of linezolid resistance in animal settings.

scholarly journals Evolution and Global Dissemination of Macrolide-Resistant Group A Streptococci

2006 ◽  
Vol 50 (9) ◽  
pp. 2903-2911 ◽  
Author(s):  
D. Ashley Robinson ◽  
Joyce A. Sutcliffe ◽  
Wezenet Tewodros ◽  
Anand Manoharan ◽  
Debra E. Bessen
Keyword(s):  
Resistance Gene ◽  
Resistance Genes ◽  
Horizontal Transfer ◽  
Macrolide Resistance ◽  
Evolutionary Relationships ◽  
Strain Typing ◽  
Group A Streptococci ◽  
Group A ◽  
Resistant Group ◽  
Genetic Events

ABSTRACT Macrolide-resistant group A streptococci (MRGAS) have been recovered from many countries worldwide. However, the strain typing information that is available has been insufficient for estimating the total number of macrolide-resistant clones, their geographic distributions, and their evolutionary relationships. In this study, sequence-based strain typing was used to characterize 212 MRGAS isolates from 34 countries. Evaluation of clonal complexes, emm type, and resistance gene content [erm(A), erm(B), mef(A), and undefined] indicate that macrolide resistance was acquired by GAS organisms via ≥49 independent genetic events. In contrast to other collections of mostly susceptible GAS, genetic diversification of MRGAS clones has occurred primarily by mutation rather than by recombination. Twenty-two MRGAS clonal complexes were recovered from more than one continent; intercontinental strains represent nearly 80% of the MRGAS isolates under study. The findings suggest that horizontal transfer of macrolide resistance genes to numerous genetic backgrounds and global dissemination of resistant clones and their descendants are both major components of the present-day macrolide resistance problem found within this species.

scholarly journals Expansion and persistence of antibiotic-specific resistance genes following antibiotic treatment

2020 ◽  
Author(s):  
Kang Kang ◽  
Lejla Imamovic ◽  
Maria-Anna Misiakou ◽  
Maria Bornakke Sørensen ◽  
Yoshitaro Heshiki ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Gut Microbiota ◽  
Resistance Gene ◽  
Antibiotic Treatment ◽  
Relative Abundance ◽  
Resistance Genes ◽  
Specific Resistance ◽  
Specific Gene ◽  
Antibiotic Administration ◽  
Human Gut

Abstract Background. Oral antibiotics are commonly prescribed to non-hospitalized adults. However, antibiotic-induced changes on the human gut microbiome are often investigated in cohorts with pre-existing health conditions and/or concomitant medication, leaving the effects of antibiotics not completely understood.Results. We used a combination of omic approaches to comprehensively assess the effects of antibiotics on the gut microbiota and particularly the gut resistome of a small cohort of healthy adults. We observed that 3 to 19 species per individual proliferated during antibiotic treatment and Gram-negative species expanded significantly in relative abundance. While the overall relative abundance of antibiotic resistance gene homologues did not significantly change, antibiotic-specific gene homologues with presumed resistance towards the administered antibiotics were common in proliferating species and significantly increased in relative abundance. Virome sequencing and plasmid analysis showed the expansion of antibiotic-specific resistance gene homologues even three months after antibiotic administration, while paired-end read analysis suggested their dissemination among different species.Conclusions. These results suggest that antibiotic treatment can lead to a persistent expansion of antibiotic resistance genes in the human gut microbiota and provide further data in support of good antibiotic stewardship.

scholarly journals The Novel Macrolide Resistance Genes mef(D), msr(F), and msr(H) Are Present on Resistance Islands in Macrococcus canis, Macrococcus caseolyticus, and Staphylococcus aureus

2020 ◽  
Vol 64 (5) ◽  
Author(s):  
Sybille Schwendener ◽  
Valentina Donà ◽  
Vincent Perreten
Keyword(s):  
Staphylococcus Aureus ◽  
Resistance Gene ◽  
Resistance Genes ◽  
Methicillin Resistance ◽  
Macrolide Resistance ◽  
Moderate Increase ◽  
The Novel ◽  
Integrase Gene ◽  
Content Type ◽  
And Staphylococcus Aureus

ABSTRACT Chromosomal resistance islands containing the methicillin resistance gene mecD (McRImecD) have been reported in Macrococcus caseolyticus. Here, we identified novel macrolide resistance genes in Macrococcus canis on similar elements, called McRImsr. These elements were also integrated into the 3′ end of the 30S ribosomal protein S9 gene (rpsI), delimited by characteristic attachment (att) sites, and carried a related site-specific integrase gene (int) at the 5′ end. They carried novel macrolide resistance genes belonging to the msr family of ABC subfamily F (ABC-F)-type ribosomal protection protein [msr(F) and msr(H)] and the macrolide efflux mef family [mef(D)]. Highly related mef(D)-msr(F) fragments were found on diverse McRImsr elements in M. canis, M. caseolyticus, and Staphylococcus aureus. Another McRImsr-like element identified in an M. canis strain lacked the classical att site at the 3′ end and carried the msr(H) gene but no neighboring mef gene. The expression of the novel resistance genes in S. aureus resulted in a low-to-moderate increase in the MIC of erythromycin but not streptogramin B. In the mef(D)-msr(F) operon, the msr(F) gene was shown to be the crucial determinant for macrolide resistance. The detection of circular forms of McRImsr and the mef(D)-msr(F) fragment suggested mobility of both the island and the resistance gene subunit. The discovery of McRImsr in different Macrococcus species and S. aureus indicates that these islands have a potential for dissemination of antibiotic resistance within the Staphylococcaceae family.

scholarly journals Occupational Exposure and Carriage of Antimicrobial Resistance Genes (tetW, ermB) in Pig Slaughterhouse Workers

2019 ◽  
Vol 64 (2) ◽  
pp. 125-137 ◽  
Author(s):  
Liese Van Gompel ◽  
Wietske Dohmen ◽  
Roosmarijn E C Luiken ◽  
Martijn Bouwknegt ◽  
Lourens Heres ◽  
...  
Keyword(s):  
Occupational Exposure ◽  
Antimicrobial Resistance ◽  
Resistance Gene ◽  
Resistance Genes ◽  
Macrolide Resistance ◽  
Resistant Bacteria ◽  
Linear Regression Models ◽  
Faecal Samples ◽  
Antimicrobial Resistance Genes ◽  
Antimicrobial Resistance Gene

Abstract Objectives Slaughterhouse staff is occupationally exposed to antimicrobial resistant bacteria. Studies reported high antimicrobial resistance gene (ARG) abundances in slaughter pigs. This cross-sectional study investigated occupational exposure to tetracycline (tetW) and macrolide (ermB) resistance genes and assessed determinants for faecal tetW and ermB carriage among pig slaughterhouse workers. Methods During 2015–2016, 483 faecal samples and personal questionnaires were collected from workers in a Dutch pig abattoir, together with 60 pig faecal samples. Human dermal and respiratory exposure was assessed by examining 198 carcass, 326 gloves, and 33 air samples along the line, next to 198 packed pork chops to indicate potential consumer exposure. Samples were analyzed by qPCR (tetW, ermB). A job exposure matrix was created by calculating the percentage of tetW and ermB positive carcasses or gloves for each job position. Multiple linear regression models were used to link exposure to tetW and ermB carriage. Results Workers are exposed to tetracycline and macrolide resistance genes along the slaughter line. Tetw and ermB gradients were found for carcasses, gloves, and air filters. One packed pork chop contained tetW, ermB was non-detectable. Human faecal tetW and ermB concentrations were lower than in pig faeces. Associations were found between occupational tetW exposure and human faecal tetW carriage, yet, not after model adjustments. Sampling round, nationality, and smoking were determinants for ARG carriage. Conclusion We demonstrated clear environmental tetracycline and macrolide resistance gene exposure gradients along the slaughter line. No robust link was found between ARG exposure and human faecal ARG carriage.

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