scholarly journals Cloning and characterization of the chromosomal arsenic resistance genes from Acidithiobacillus caldus and enhanced arsenic resistance on conjugal transfer of ars genes located on transposon TnAtcArs

Microbiology ◽  
2006 ◽  
Vol 152 (12) ◽  
pp. 3551-3560 ◽  
Author(s):  
Andre A. Kotze ◽  
I. Marla Tuffin ◽  
Shelly M. Deane ◽  
Douglas E. Rawlings
Keyword(s):  
Resistance Genes ◽  
Legionella Pneumophila ◽  
Amino Acid Identity ◽  
Conjugal Transfer ◽  
Arsenic Resistance ◽  
Moderately Thermophilic ◽  
E Coli ◽  
Acidithiobacillus Caldus ◽  
High Amino Acid

All strains of the moderately thermophilic, acidophilic, sulphur-oxidizing bacterium Acidithiobacillus caldus that have been tested contain a set of chromosomal arsenic resistance genes. Highly arsenic-resistant strains isolated from commercial arsenopyrite bio-oxidation tanks contain additional transposon-located (TnAtcArs) arsenic resistance genes. The chromosomal At. caldus ars genes were cloned and found to consist of arsR and arsC genes transcribed in one direction, and arsB in the opposite direction. The arsRC genes were co-transcribed with ORF1, and arsB with ORF5 in both At. caldus and Escherichia coli, although deletion of ORFs 1 and 5 did not appear to affect resistance to arsenate or arsenite in E. coli. ORFs 1 and 5 have not previously been reported as part of the ars operons, and had high amino acid identity to hypothetical proteins from Polaromonas naphthalenivorus (76 %) and Legionella pneumophila (60 %), respectively. Reporter-gene studies showed that the arsenic operon of transposon origin (TnAtcArs) was expressed at a higher level, and was less tightly regulated in E. coli than were the At. caldus ars genes of chromosomal origin. Plasmid pSa-mediated conjugal transfer of TnAtcArs from E. coli to At. caldus strains lacking the transposon was successful, and resulted in greatly increased levels of resistance to arsenite.

An unusual Tn21-like transposon containing an ars operon is present in highly arsenic-resistant strains of the biomining bacterium Acidithiobacillus caldus

Microbiology ◽  
2005 ◽  
Vol 151 (9) ◽  
pp. 3027-3039 ◽  
Author(s):  
I. Marla Tuffin ◽  
Peter de Groot ◽  
Shelly M. Deane ◽  
Douglas E. Rawlings
Keyword(s):  
Resistance Genes ◽  
Nadh Oxidase ◽  
Sequence Similarity ◽  
Northern Hybridization ◽  
Terminal Inverted Repeat ◽  
Transposition Frequency ◽  
Arsenic Resistance ◽  
E Coli ◽  
Acidithiobacillus Caldus ◽  
Cbs Domain

A transposon, TnAtcArs, that carries a set of arsenic-resistance genes was isolated from a strain of the moderately thermophilic, sulfur-oxidizing, biomining bacterium Acidithiobacillus caldus. This strain originated from a commercial plant used for the bio-oxidation of gold-bearing arsenopyrite concentrates. Continuous selection for arsenic resistance over many years had made the bacterium resistant to high concentrations of arsenic. Sequence analysis indicated that TnAtcArs is 12 444 bp in length and has 40 bp terminal inverted repeat sequences and divergently transcribed resolvase and transposase genes that are related to the Tn21-transposon subfamily. A series of genes consisting of arsR, two tandem copies of arsA and arsD, two ORFs (7 and 8) and arsB is situated between the resolvase and transposase genes. Although some commercial strains of At. caldus contained the arsDA duplication, when transformed into Escherichia coli, the arsDA duplication was unstable and was frequently lost during cultivation or if a plasmid containing TnAtcArs was conjugated into a recipient strain. TnAtcArs conferred resistance to arsenite and arsenate upon E. coli cells. Deletion of one copy of arsDA had no noticeable effect on resistance to arsenite or arsenate in E. coli. ORFs 7 and 8 had clear sequence similarity to an NADH oxidase and a CBS-domain-containing protein, respectively, but their deletion did not affect resistance to arsenite or arsenate in E. coli. TnAtcArs was actively transposed in E. coli, but no increase in transposition frequency in the presence of arsenic was detected. Northern hybridization and reporter gene studies indicated that although ArsR regulated the 10 kb operon containing the arsenic-resistance genes in response to arsenic, ArsR had no effect on the regulation of genes associated with transposition activity.

Functional and Structural Characterization of Acquired Pan-Aminoglycoside Resistance 16S rRNA Methyltransferase NpmB1

2021 ◽  
Author(s):  
Akito Kawai ◽  
Masahiro Suzuki ◽  
Kentaro Tsukamoto ◽  
Yusuke Minato ◽  
Yohei Doi
Keyword(s):  
Amino Acid ◽  
16S Rrna ◽  
Amino Acid Identity ◽  
Single Amino Acid ◽  
Aminoglycoside Resistance ◽  
E Coli ◽  
The United Kingdom ◽  
Amino Acid Variant ◽  
A Site

Post-translational methylation of the A site of 16S rRNA at position A1408 leads to pan-aminoglycoside resistance encompassing both 4,5- and 4,6-disubstituted 2-deoxystreptamine (DOS) aminoglycosides. To date, NpmA is the only acquired enzyme with such function. Here, we present function and structure of NpmB1 whose sequence was identified in Escherichia coli genomes registered from the United Kingdom. NpmB1 possesses 40% amino acid identity with NpmA1 and confers resistance to all clinically relevant aminoglycosides including 4,5-DOS agents. Phylogenetic analysis of NpmB1 and NpmB2, its single amino acid variant, revealed that the encoding gene was likely acquired by E. coli from a soil bacterium. The structure of NpmB1 suggests that it requires a structural change of the β6/7 linker in order to bind to 16S rRNA. These findings establish NpmB1 and NpmB2 as the second group of acquired pan-aminoglycoside resistance 16S rRNA methyltransferases.

scholarly journals 480. Molecular Characterization of Multidrug-Resistant Gram-Negative Pathogens in Three Tertiary Care Hospitals in Egypt

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S235-S235
Author(s):  
Amani Kholy ◽  
Samia A Girgis ◽  
Arwa R Elmanakhly ◽  
Mervat A F Shetta ◽  
Dalia El- Kholy ◽  
...  
Keyword(s):  
Molecular Characterization ◽  
Resistance Genes ◽  
Genetic Basis ◽  
Tertiary Care ◽  
Carbapenem Resistance ◽  
Resistance Mechanisms ◽  
Gram Negative ◽  
E Coli ◽  
Tertiary Care Hospitals

Abstract Background High rates of AMR among Gram-negative bacilli (GNB) have been reported from Egypt for almost 2 decades. Surveillance and identifying the genetic basis of AMR provide important information to optimize patient care. As there is no adequate data on the genetic basis of AMR in Egypt, we aimed to identify the molecular characterization of multi-drug-resistant (MDR) Gram-negative pathogens (GNP). Methods Three major tertiary-care hospitals in Egypt participated in the “Study for Monitoring Antimicrobial Resistance Trends” (SMART) from 2014 to 2016. Consecutive GNPs were identified and their susceptibility to antimicrobials were tested. Molecular identification of ESBL, AmpC, and carbapenemase resistance genes was conducted on MDR isolates. Results We enrolled 1,070 consecutive Gram-negative isolates; only one isolate per patient according to the standard protocol of (SMART). During 2014–2015, 578 GNP were studied. Enterobacteriaceae comprised 66% of the total isolates. K. pneumoniae and E. coli were the most common (29.8% and 29.4%). K. pneumoniae and E. coli were the predominant organisms in IAI (30.5% and 30.1%, respectively) and UTI (and 38.9% and 48.6%, respectively), while Acinetobacter baumannii was the most prevalent in RTI (40.2%). ESBL producers were phenotypically detected in 53% of K. pneumoniae, and 68% of E. coli. During 2016, 495 GNP were studied. ESBL continued to be high. For E. coli and K. pneunomiea, the most active antimicrobials were amikacin (≥93%), imipenem/meropenem (≥87%) and colistin (97%). Genetic study of ertapenem-resistant isolates and 50% of isolates with ESBL phenotype revealed ESβL production in more than 90% of isolates; blaCTXM-15 was detected in 71.4% and 68.5% in K. pneumoniae and E. coli, respectively, blaTEM-OSBL in 48.5% and47.5% of K. pneumoniae and E. coli, respectively. Carbapenem resistance genes were detected in 45.4% of isolates. In K. pneumoniae, OXA-48 dominated (40.6%), followed by NDM1 (23.7%) and OXA-232 (4.5%). Conclusion Our study detected alarming rates of resistance and identified many resistance mechanisms in clinical isolates from Egyptian hospitals. These high rates highlight the importance of continuous monitoring of the resistance trend and discovering the novel resistant mechanisms of resistance, and the underscores a national antimicrobial stewardship plan in Egypt. Disclosures All authors: No reported disclosures.

Characterization of Antibiotic Resistance E. Coli and Antibiotic Resistance Genes in Aquatic Environment of Taihu Lake, China

2013 ◽  
Vol 295-298 ◽  
pp. 630-634 ◽  
Author(s):  
Ni Ni Han ◽  
Song He Zhang ◽  
Pei Fang Wang ◽  
Chao Wang
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Surface Water ◽  
Resistance Genes ◽  
Taihu Lake ◽  
Antibiotic Resistance Genes ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Realtime Pcr

The aims of this study are to evaluate multiple antibiotic resistant Escherichia coli isolated from surface water and to investigate the presence and distribution antibiotic resistance genes (ARGs) in sediments of Taihu Lake. The results show that the presentence of four ARGs concentrations in the sediments of the lake was in sequence: strB>qnrB>strA>qnrS, as determined by realtime-PCR technique. The southwest and east areas of Taihu Lake were polluted seriously than other areas from all kinds of antibiotics. The screening Escherichia coli had a higher resistance to streptomycin, tetracycline and ampicillin than other four antibiotics, and had a lowest resistance to levofloxacin.

scholarly journals Characterization of Integrons and Antimicrobial Resistance in Escherichia coli Sequence Type 131 Isolates

2020 ◽  
Vol 2020 ◽  
pp. 1-8 ◽  
Author(s):  
Jiangqing Huang ◽  
Fangjun Lan ◽  
Yanfang Lu ◽  
Bin Li
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Antimicrobial Resistance ◽  
Resistance Genes ◽  
Sequence Type ◽  
Broth Culture ◽  
Gene Cassettes ◽  
E Coli ◽  
Class 1

Background. Escherichia coli sequence type 131 (ST131) is an important multidrug-resistant extraintestinal pathogen, which can cause many kinds of infections. Integrons may play a crucial role in the dissemination of antibiotic resistance genes. The purpose of this study was to characterize the prevelance of integrons among E. coli ST131 strains in China. Methods. Eighty-three E. coli ST131 isolates were used in this study. The antibiotic susceptibility test was performed by the disk diffusion method. The presence and characterization of class 1, 2, and 3 integrons, as well as promotor of gene cassettes and other antimicrobial resistance genes, were detected by PCR and DNA sequencing. Transfer of integrons was carried out using a broth culture mating method. Clonal relatedness of E. coli ST131 isolates was analyzed by PFGE. Results. Overall, 26.5% (22/83) of the E. coli ST131 isolates carried class 1 integrons. Class 2 and 3 integrons were not found in this study. Two types of gene cassette arrays were demonstrated in this study and were as follows: dfrA17-aadA5 and aac(6′)-Ib-cr-cmlA5. Only one type of Pc promoter variant was detected among 22 integron-positive isolates (PcW). In vivo transfer of integron was successful for 9 of integron-positive E. coli ST131 isolates harboring resistance gene cassettes. Results of PFGE demonstrated that the integron-positive E. coli ST131 isolates were grouped into 12 different PFGE clusters. Conclusions. Our study showed a low prevalence of integrons was detected in E. coli ST131. Continued surveillance of this mobile genetic element should be performed to study the evolution of antibiotic resistance among E. coli ST131.

scholarly journals Genotypic antimicrobial resistance characterization of E. coli from dairy calves at high risk of respiratory disease administered enrofloxacin or tulathromycin

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
R. V. Pereira ◽  
C. Foditsch ◽  
J. D. Siler ◽  
S. C. Dulièpre ◽  
C. Altier ◽  
...  
Keyword(s):  
High Risk ◽  
Antimicrobial Resistance ◽  
Respiratory Disease ◽  
Resistance Genes ◽  
Tetracycline Resistance ◽  
Control Group ◽  
E Coli ◽  
Tetracycline Resistance Genes ◽  
Antimicrobial Resistance Genes

Abstract The objective of this study was to evaluate the longitudinal effect of enrofloxacin or tulathromycin use in calves at high risk of bovine respiratory disease (BRD) on antimicrobial resistance genes and mutation in quinolone resistance-determining regions (QRDR) in fecal E. coli. Calves at high risk of developing BRD were randomly enrolled in one of three groups receiving: (1) enrofloxacin (ENR; n = 22); (2) tulathromycin (TUL; n = 24); or (3) no treatment (CTL; n = 21). Fecal samples were collected at enrollment and at 7, 28, and 56 days after beginning treatment, cultured for Escherichiacoli (EC) and DNA extracted. Isolates were screened for cephalosporin, quinolone and tetracycline resistance genes using PCR. QRDR screening was conducted using Sanger sequencing. The only resistance genes detected were aac(6′)Ib-cr (n = 13), bla-CTX-M (n = 51), bla-TEM (n = 117), tetA (n = 142) and tetB (n = 101). A significantly higher detection of gyrA mutated at position 248 at time points 7 (OR = 11.5; P value = 0.03) and 28 (OR = 9.0; P value = 0.05) was observed in the ENR group when compared to calves in the control group. Our findings support a better understanding of the potential impacts from the use of enrofloxacin in calves on the selection and persistence of resistance.

Risk Characterization of Antibiotic Resistance in Bacteria Isolated from Backyard, Organic, and Regular Commercial Eggs

2019 ◽  
Vol 82 (3) ◽  
pp. 422-428 ◽  
Author(s):  
ALEJANDRO FENOLLAR ◽  
EVA DOMÉNECH ◽  
MARÍA ANTONIA FERRÚS ◽  
ANA JIMÉNEZ-BELENGUER
Keyword(s):  
Resistance Genes ◽  
Organic Production ◽  
Organic N ◽  
Salmonella Spp ◽  
E Coli ◽  
Antimicrobial Resistance Genes ◽  
Amoxicillin Clavulanate ◽  
Resistant Strains ◽  
Standard Production

ABSTRACT This study was conducted to assess the risk due to antimicrobial-resistant strains of Salmonella spp., Listeria monocytogenes, and Escherichia coli isolated from the eggshell and the contents of eggs bought in markets in Valencia (Spain). Thirty-four samples from three different production styles were analyzed: standard (n = 34), organic (n = 16), and backyard (n = 10) eggs. L. monocytogenes was not isolated in any style of production. Only one strain of Salmonella was isolated from standard production, which was resistant to ciprofloxacin and amoxicillin. E. coli strains were resistant in 22% of the isolates from organic production, 12.25% from standard production, and 11.23% from backyard production. In all cases, the highest resistance was observed for amoxicillin-clavulanate. None of the isolates from standard and backyard eggs were resistant to chloramphenicol, ciprofloxacin, gentamycin, and streptomycin, while only ceftriaxone was found to be effective against all E. coli isolates from organic eggs. β-Lactamase genes blaTEM, blaSHV, and blaCMY-2 and the resistance genes for tetracycline tetA, tetB, and tetC were tested. The most commonly detected antimicrobial resistance genes among the E. coli isolates were tetA (49.30%), blaTEM (47.89%), and tetB (36.62%). Overall, a maximum public health risk is associated with β-lactam antibiotics.

scholarly journals Characterization of Extended-Spectrum β-Lactamase-Producing and AmpC β-Lactamase-Producing Enterobacterales Isolated from Companion Animals in Korea

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 249
Author(s):  
Se Ra Shin ◽  
Seong Mi Noh ◽  
Woo Kyung Jung ◽  
Sook Shin ◽  
Young Kyung Park ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Genetic Relatedness ◽  
Bacterial Species ◽  
Klebsiella Oxytoca ◽  
Companion Animals ◽  
E Coli ◽  
South Korean ◽  
Extended Spectrum ◽  
Single Clone

The emergence of extended-spectrum cephalosporin (ESC)-resistant Gram-negative bacteria is of great concern in both human and veterinary medicine. The aim of this study was to investigate ESC-resistant bacterial isolates from companion animals in South Korea between 2017 and 2019. Isolates with ESC resistance genes, which were identified by PCR, were assessed for genetic relatedness by multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). In total, 91 ESC-resistant Escherichia coli, Klebsiella spp., Serratia spp., and Enterobacter cloacae isolates harbored the blaTEM gene. Among other ESC resistance genes, blaCTX-M-15, blaCIT, and blaCTX-M-55 were predominantly detected in E. coli isolates, whereas blaSHV and blaDHA were more frequently detected in Klebsiella pneumoniae isolates. In addition, all blaEBC-positive isolates were classified as E. cloacae. From the MLST results, blaCTX-M-9-carrying ST131, blaCIT-carrying ST405, and blaCTX-M-1-carrying ST3285 strains were dominant among E. coli isolates. ST273 and ST275 strains harboring blaSHV were frequently detected in K. pneumoniae isolates. Various sequence types were obtained in E. cloacae and Klebsiella oxytoca isolates. All isolates demonstrated unique PFGE profiles (<57–98% similarity) and were unlikely to be derived from a single clone. The present study reveals the presence and wide genetic distribution of ESC-resistant bacterial species in South Korean companion animals.

scholarly journals Molecular Characterization of β-Lactamase Producing Genes and Integrons in Diarrheagenic Escherichia Coli From Diarrheal Children Less Than Five Years of Age in Ouagadougou, Burkina Faso.

2021 ◽  
Author(s):  
Rene Dembele ◽  
Wendpoulomdé A.D. Kaboré ◽  
Issiaka Soulama ◽  
Oumar Traoré ◽  
Nafissatou Ouédraogo ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Molecular Characterization ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Control Measures ◽  
Diffusion Method ◽  
Biochemical Tests ◽  
Disk Diffusion Method ◽  
E Coli

Abstract Background The aim of this study was to determine the resistance of diarrheagenic Escherichia coli strains to β-lactams antibiotics and to perform the molecular characterization of Extended Spectrum β-lactamases (ESBL) and integrons genes. Methods This study was carried out from August 2013 to October 2015 and involved 31 DEC strains isolated from diarrheal stools samples collected from children less than five years of age. The identification and characterization of DEC strains was done through the standard biochemical tests those were confirmed using API 20E and Polymerase Chain Reaction (PCR). The determination of antimicrobial resistance was realized by the disk diffusion method then an amplification of the β-lactamase resistance genes and integrons by PCR was done. Results Out of the 419 E. coli strains identified, 31 isolates (7.4%) harbored the DEC virulence genes. From these DEC, 21 (67.7%) were ESBL-producing E. coli. Susceptibility to ESBL-producing E. coli showed that the majority of isolates were highly resistant to amoxicillin (77.4%), amoxicillin clavulanic acid (77.4%) and piperacillin (64.5%). The following antibiotic resistance genes and integron were identified from the 31 DEC isolates: blaTEM (6.5%), blaSHV (19.4%), blaOXA (38.7%) blaCTX−M (9.7%), Int1 (58.1%) and Int3 (19.4%). No class 2 integrons (Int2) was characterized. Conclusions Because of the high prevalence of multidrug-resistant ESBL organisms found in this study among pediatric patients, there is a need of stringent pediatric infection control measures.

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