scholarly journals Effect of frameshift mutagen acriflavine on control of resistance genes in Acinetobacter baumannii

2011 ◽  
Vol 60 (2) ◽  
pp. 211-215 ◽  
Author(s):  
B. S. Lopes ◽  
A. Hamouda ◽  
J. Findlay ◽  
S. G. B. Amyes
Keyword(s):  
Gene Expression ◽  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Resistance Genes ◽  
Outer Membrane Proteins ◽  
Antibiotic Resistance Gene ◽  
Antibiotic Resistance Genes ◽  
Multidrug Resistant ◽  
The Body

Acinetobacter baumannii is a Gram-negative pathogenic bacterium that often exhibits a multidrug-resistant phenotype causing infections at various sites of the body and increasingly leading to septicaemic shock. This study evaluated the role of acriflavine, a frameshift mutagen, on the movement of insertion sequence ISAba1 in clinical isolates of A. baumannii, with the focus on changes in expression levels of the bla ADC and bla OXA-51-like genes. Resistance profiles were assessed with consideration of ISAba1 acting as a promoter upstream of the bla ADC or bla OXA-51-like gene. ISAba1 movement was observed in the acriflavine mutants Ab153M and Ab1225M. Ab153M exhibited an increase in the MIC values of carbapenems and ceftazidime, with ISAba1 gained upstream of the bla ADC and bla OXA-51-like genes, correlating with an increase in gene expression. Reduced expression of the 17, 23 and 25 kDa outer-membrane proteins (OMPs) was also observed in Ab153M. There was a significant decrease in MIC values of carbapenems with the loss of ISAba1 upstream of the bla ADC and bla OXA-51-like genes in strain Ab1225M, and a significant decrease in bla OXA-51-like gene expression and, to a lesser extent, in bla ADC expression. Ab1225M and a serially subcultured Ab1225 strain (Ab1225s) exhibited overexpression of the 17, 23, 25 and 27 kDa OMPs. There was a decrease in MIC values of the carbapenems and piperacillin/tazobactam but not of ceftazidime in Ab1225s, which had ISAba1 upstream of the bla ADC and bla OXA-51-like genes. A significant decrease in bla OXA-51-like expression was observed in Ab1225s, whereas the expression of bla ADC was similar to that in the Ab1225 parental strain. The attenuation in this strain may be due to overexpression of OMPs and it is clear that, even if ISAba1 is present upstream of an antibiotic resistance gene, it may not necessarily contribute towards the overexpression of antibiotic resistance genes (bla OXA-51-like in Ab1225s). Movement of the IS element within the A. baumannii chromosome may be an important regulatory mechanism employed by the bacterium under particular stress conditions, and the ability to upregulate the expression of antibiotic resistance genes is likely to be an important factor in the pathogenicity of this bacterium.

scholarly journals Antimicrobial Resistance and CRISPR Typing Among Salmonella Isolates From Poultry Farms in China

2021 ◽  
Vol 12 ◽  
Author(s):  
Cui Li ◽  
Yulong Wang ◽  
Yufeng Gao ◽  
Chao Li ◽  
Boheng Ma ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Antibiotic Resistance Gene ◽  
Antibiotic Resistance Genes ◽  
Direct Repeat ◽  
Epidemiological Data ◽  
Multidrug Resistant ◽  
Typing Method ◽  
Crispr Locus ◽  
Research Areas

Although knowledge of the clustered regularly interspaced short palindromic repeat (CRISPR)-Cas system has been applied in many research areas, comprehensive studies of this system in Salmonella, particularly in analysis of antibiotic resistance, have not been reported. In this work, 75 Salmonella isolates obtained from broilers or broilers products were characterized to determine their antimicrobial susceptibilities, antibiotic resistance gene profiles, and CRISPR array diversities, and genotyping was explored. In total, 80.00% (60/75) of the strains were multidrug resistant, and the main pattern observed in the isolates was CN-AZM-AMP-AMC-CAZ-CIP-ATM-TE-SXT-FOS-C. The resistance genes of streptomycin (aadA), phenicol (floR-like and catB3-like), β-lactams (blaTEM, blaOXA, and blaCTX), tetracycline [tet(A)-like], and sulfonamides (sul1 and sul2) appeared at higher frequencies among the corresponding resistant isolates. Subsequently, we analyzed the CRISPR arrays and found 517 unique spacer sequences and 31 unique direct repeat sequences. Based on the CRISPR spacer sequences, we developed a novel typing method, CRISPR locus three spacer sequences typing (CLTSST), to help identify sources of Salmonella outbreaks especially correlated with epidemiological data. Compared with multi-locus sequence typing (MLST), conventional CRISPR typing (CCT), and CRISPR locus spacer pair typing (CLSPT), discrimination using CLTSST was weaker than that using CCT but stronger than that using MLST and CLSPT. In addition, we also found that there were no close correlations between CRISPR loci and antibiotics but had close correlations between CRISPR loci and antibiotic resistance genes in Salmonella isolates.

scholarly journals Longitudinal assessment of antibiotic resistance gene profiles in gut microbiomes of infants at risk of eczema

2020 ◽  
Author(s):  
Evelyn Loo ◽  
Amanda Zain ◽  
Gaik Chin Yap ◽  
Rikky W Purbojati ◽  
Daniela I Drautz-Moses ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Cohort Study ◽  
Resistance Genes ◽  
Pathogenic Bacteria ◽  
Antibiotic Resistance Gene ◽  
Antibiotic Resistance Genes ◽  
Multidrug Resistant ◽  
First Year ◽  
Beta Lactam ◽  
First Year Of Life

Abstract Background While there is increasing knowledge about the gut microbiome, the factors influencing and the significance of the gut resistome are still not well understood. Infant gut commensals risk transferring multidrug-resistant antibiotic resistance genes (ARGs) to pathogenic bacteria. The rapid spread of multidrug-resistant pathogenic bacteria is a worldwide public health concern. Better understanding the naïve infant gut resistome may build the evidence base for antimicrobial stewardship in both humans and in the food industry. Given the high carriage rate of extended spectrum beta-lactamase (ESBL)- producing Enterobacteriaceae in Asia, we aimed to evaluate community prevalence, dynamics, and longitudinal changes in antibiotic resistance gene (ARG) profiles and prevalence of ESBL-producing .E coli and K. pneumoniae in the intestinal microbiome of infants participating in the Growing Up in Singapore Towards Healthy Outcomes (GUSTO) study, a longitudinal cohort study of pregnant women and their infants. Methods We analysed ARGs in the first year of life among 75 infants who had stool samples collected at multiple timepoints using metagenomics. Results The mean number of ARGs per infant increased with age. The most common ARGs identified confer resistance to aminoglycoside, beta-lactam, macrolide and tetracycline antibiotics; all infants harboured these antibiotic resistance genes at some point in the first year of life. Few ARGs persisted throughout the first year of life. Beta-lactam resistant Escherichia coli and Klebsiella pneumoniae were detected in 4 (5.3%) and 32 (42.7%) of subjects respectively. Conclusion In this longitudinal cohort study of infants living in a region with high endemic antibacterial resistance, we demonstrate that the majority of the infants harboured several antibiotic resistance genes in their gut and showed that the infant gut resistome is diverse and dynamic over the first year of life.

scholarly journals What is the role of the environment in the emergence of novel antibiotic resistance genes? – A modelling approach

2021 ◽  
Author(s):  
Johan Bengtsson-Palme ◽  
Viktor Jonsson ◽  
Stefanie Heß
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Quantitative Data ◽  
Antibiotic Resistance Gene ◽  
Antibiotic Resistance Genes ◽  
Resistant Bacteria ◽  
Minor Role ◽  
Model Framework ◽  
Animal Pathogens

AbstractIt is generally accepted that intervention strategies to curb antibiotic resistance cannot solely focus on human and veterinary medicine but must also consider environmental settings. While the environment clearly has a role in the transmission of resistant bacteria, it is less clear what role it plays in the emergence of novel types of resistance. It has been suggested that the environment constitutes an enormous recruitment ground for resistance genes to pathogens, but the extent to which this actually happens is unknown. In this study, we built a model framework for resistance emergence and used the available quantitative data on the relevant processes to identify the steps which are limiting the appearance of antibiotic resistance determinants in human or animal pathogens. We also assessed the effect of uncertainty in the available data on the model results. We found that in a majority of scenarios, the environment would only play a minor role in the emergence of novel resistance genes. However, the uncertainty around this role is enormous, highlighting an urgent need of more quantitative data to understand the role of the environment in antibiotic resistance development. Specifically, more data is most needed on the fitness costs of antibiotic resistance gene (ARG) carriage, the degree of dispersal of resistant bacteria from the environment to humans, but also the rates of mobilization and horizontal transfer of ARGs. Quantitative data on these processes is instrumental to determine which processes that should be targeted for interventions to curb development and transmission of resistance.

Longitudinal assessment of antibiotic resistance gene profiles in gut microbiomes of infants at risk of eczema

2020 ◽  
Author(s):  
Evelyn Loo(Former Corresponding Author) ◽  
Amanda Zain ◽  
Gaik Chin Yap ◽  
Rikky W Purbojati ◽  
Daniela I Drautz-Moses ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Cohort Study ◽  
Resistance Genes ◽  
Pathogenic Bacteria ◽  
Antibiotic Resistance Gene ◽  
Antibiotic Resistance Genes ◽  
Multidrug Resistant ◽  
First Year ◽  
Beta Lactam ◽  
First Year Of Life

Abstract Background While there is increasing knowledge about the gut microbiome, the factors influencing and the significance of the gut resistome are still not well understood. Infant gut commensals risk transferring multidrug-resistant antibiotic resistance genes (ARGs) to pathogenic bacteria. The rapid spread of multidrug-resistant pathogenic bacteria is a worldwide public health concern. Better understanding the naïve infant gut resistome may build the evidence base for antimicrobial stewardship in both humans and in the food industry. Given the high carriage rate of extended spectrum beta-lactamase (ESBL)- producing Enterobacteriaceae in Asia, we aimed to evaluate community prevalence, dynamics, and longitudinal changes in antibiotic resistance gene (ARG) profiles and prevalence of ESBL-producing E. coli and K. pneumoniae in the intestinal microbiome of infants participating in the Growing Up in Singapore Towards Healthy Outcomes (GUSTO) study, a longitudinal cohort study of pregnant women and their infants. Methods: We analysed ARGs in the first year of life among 75 infants at risk of eczema who had stool samples collected at multiple timepoints using metagenomics. Results: The mean number of ARGs per infant increased with age. The most common ARGs identified confer resistance to aminoglycoside, beta-lactam, macrolide and tetracycline antibiotics; all infants harboured these antibiotic resistance genes at some point in the first year of life. Few ARGs persisted throughout the first year of life. Beta-lactam resistant Escherichia coli and Klebsiella pneumoniae were detected in 4 (5.3%) and 32 (42.7%) of subjects respectively. Conclusion: In this longitudinal cohort study of infants living in a region with high endemic antibacterial resistance, we demonstrate that majority of the infants harboured several antibiotic resistance genes in their gut and showed that the infant gut resistome is diverse and dynamic over the first year of life.

scholarly journals Genomic Analysis of the Multidrug-Resistant Acinetobacter baumannii Strain MDR-ZJ06 Widely Spread in China

2011 ◽  
Vol 55 (10) ◽  
pp. 4506-4512 ◽  
Author(s):  
Hua Zhou ◽  
Tongwu Zhang ◽  
Dongliang Yu ◽  
Borui Pi ◽  
Qing Yang ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Genomic Analysis ◽  
Multidrug Resistant ◽  
Whole Genome Sequence ◽  
Whole Genome ◽  
Content Type ◽  
Resistance Island

ABSTRACTWe previously reported that the multidrug-resistant (MDR)Acinetobacter baumanniistrain MDR-ZJ06, belonging to European clone II, was widely spread in China. In this study, we report the whole-genome sequence of this clinically important strain. A 38.6-kb AbaR-type genomic resistance island (AbaR22) was identified in MDR-ZJ06. AbaR22 has a structure similar to those of the resistance islands found inA. baumanniistrains AYE and AB0057, but it contained only a few antibiotic resistance genes. The region of resistant gene accumulation as previously described was not found in AbaR22. In the chromosome of the strain MDR-ZJ06, we identified the geneblaoxa-23in a composite transposon (Tn2009). Tn2009shared the backbone with otherA. baumanniitransponsons that harborblaoxa-23, but it was bracketed by two ISAba1elements which were transcribed in the same orientation. MDR-ZJ06 also expressed thearmAgene on its plasmid pZJ06, and this gene has the same genetic environment as thearmAgene of theEnterobacteriaceae. These results suggest variability of resistance acquisition even in closely relatedA. baumanniistrains.

scholarly journals Metagenomic characterization of bacterial community and antibiotic resistance genes in representative ready-to-eat food in southern China

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
YiMing Li ◽  
WeiWei Cao ◽  
ShuLi Liang ◽  
Shinji Yamasaki ◽  
Xun Chen ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Bacterial Community ◽  
Resistance Genes ◽  
Southern China ◽  
Variation Partitioning ◽  
Antibiotic Resistance Gene ◽  
Antibiotic Resistance Genes ◽  
Multidrug Resistant ◽  
Food Samples ◽  
Rrna Gene

Abstract Ready-to-eat (RTE) foods have been considered to be reservoirs of antibiotic resistance bacteria, which constitute direct threat to human health, but the potential microbiological risks of RTE foods remain largely unexplored. In this study, the metagenomic approach was employed to characterize the comprehensive profiles of bacterial community and antibiotic resistance gene (ARG) in 18 RTE food samples (8 RTE meat, 7 RTE vegetables and 3 RTE fruit) in southern China. In total, the most abundant phyla in RTE foods were Proteobacteria, Firmicutes, Cyanobacteria, Bacteroidetes and Actinobacteria. 204 ARG subtypes belonging to 18 ARG types were detected with an abundance range between 2.81 × 10−5 and 7.7 × 10−1 copy of ARG per copy of 16S rRNA gene. Multidrug-resistant genes were the most predominant ARG type in the RTE foods. Chloramphenicol, macrolide-lincosamide-streptogramin, multidrug resistance, aminoglycoside, bacitracin, tetracycline and β-lactam resistance genes were dominant, which were also associated with antibiotics used extensively in human medicine or veterinary medicine/promoters. Variation partitioning analysis indicated that the join effect of bacterial community and mobile genetic elements (MGEs) played an important role in the resistome alteration. This study further deepens the comprehensive understanding of antibiotic resistome and the correlations among the antibiotic resistome, microbiota, and MGEs in the RTE foods.

scholarly journals Genome-wide correlation analysis suggests different roles of CRISPR-Cas systems in the acquisition of antibiotic resistance genes in diverse species

2019 ◽  
Vol 374 (1772) ◽  
pp. 20180384 ◽  
Author(s):  
Saadlee Shehreen ◽  
Te-yuan Chyou ◽  
Peter C. Fineran ◽  
Chris M. Brown
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Evolutionary Dynamics ◽  
Antibiotic Resistance Gene ◽  
Antibiotic Resistance Genes ◽  
Important Species ◽  
Fitness Advantage ◽  
Genome Wide ◽  
Clinical Environments

CRISPR-Cas systems are widespread in bacterial and archaeal genomes, and in their canonical role in phage defence they confer a fitness advantage. However, CRISPR-Cas may also hinder the uptake of potentially beneficial genes. This is particularly true under antibiotic selection, where preventing the uptake of antibiotic resistance genes could be detrimental. Newly discovered features within these evolutionary dynamics are anti-CRISPR genes, which inhibit specific CRISPR-Cas systems. We hypothesized that selection for antibiotic resistance might have resulted in an accumulation of anti-CRISPR genes in genomes that harbour CRISPR-Cas systems and horizontally acquired antibiotic resistance genes. To assess that question, we analysed correlations between the CRISPR-Cas, anti-CRISPR and antibiotic resistance gene content of 104 947 reference genomes, including 5677 different species. In most species, the presence of CRISPR-Cas systems did not correlate with the presence of antibiotic resistance genes. However, in some clinically important species, we observed either a positive or negative correlation of CRISPR-Cas with antibiotic resistance genes. Anti-CRISPR genes were common enough in four species to be analysed. In Pseudomonas aeruginosa , the presence of anti-CRISPRs was associated with antibiotic resistance genes. This analysis indicates that the role of CRISPR-Cas and anti-CRISPRs in the spread of antibiotic resistance is likely to be very different in particular pathogenic species and clinical environments. This article is part of a discussion meeting issue ‘The ecology and evolution of prokaryotic CRISPR-Cas adaptive immune systems’.

scholarly journals Multidrug-resistant enterococci in the hospital environment: detection of novel vancomycin-resistant E. faecium clone ST910

2016 ◽  
Vol 10 (08) ◽  
pp. 799-806 ◽  
Author(s):  
Raoudha Dziri ◽  
Carmen Lozano ◽  
Leila Ben Said ◽  
Ridha Bellaaj ◽  
Abdellatif Boudabous ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Multidrug Resistant ◽  
Positive Sample ◽  
Hospital Environment ◽  
Resistant Bacteria ◽  
Antimicrobial Resistance Genes ◽  
Vancomycin Resistant

Introduction: The role of the hospital environment as a reservoir of resistant bacteria in Tunisia has been poorly investigated; however, it could be responsible for the transmission of multidrug-resistant bacteria. The objective was to study the prevalence of Enterococcus in the environment of a Tunisian hospital and the antibiotic resistance phenotype/genotype in recovered isolates, with special reference to vancomycin resistance. Methodology: A total of 300 samples were taken (March–June, 2013) and inoculated in Slanetz-Bartley agar plates supplemented or not supplemented with 8 µg/mL of vancomycin. Antibiotic resistance genes were tested by polymerase chain reaction (PCR). The clonal relatedness of the vanA isolates was assessed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence testing (MLST). Results: Enterococci were recovered in 33.3% of tested samples inoculated in SB medium. E faecium was the most prevalent species, followed by E. faecalis and E. casseliflavus. Antimicrobial resistance genes detected were as follows (number of isolates): erm(B) (71), tet(M) (18), aph(3’)-IIIa (27), ant(6)-Ia (15), cat(A) (4), and van(C2) (6). Vancomycin-resistant-enterococci (VRE) were recovered from 14 samples (4.7%), when tested in SB-VAN. The 14 VRE (one per positive sample) were identified as E. faecium and contained the van(A),erm(B), tet(M), ant(6)-Ia, and aph(3’)-IIIa genes. Thirteen of the VRE strains were ascribed by PFGE and MLST to a novel clone (new ST910), and only one VRE strain was typed as ST80 included in CC17. Conclusions: The emergence and spread of new clones of VRE, especially in the hospital environment in this country, could become particularly problematic.

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