scholarly journals Novel Antibiotic-Free Plasmid Selection System Based on Complementation of Host Auxotrophy in the NAD De Novo Synthesis Pathway

2010 ◽  
Vol 76 (7) ◽  
pp. 2295-2303 ◽  
Author(s):  
Wei-Ren Dong ◽  
Li-Xin Xiang ◽  
Jian-Zhong Shao

ABSTRACT The use of antibiotic resistance genes in plasmids causes potential biosafety and clinical hazards, such as the possibility of horizontal spread of resistance genes or the rapid emergence of multidrug-resistant pathogens. This paper introduces a novel auxotrophy complementation system that allowed plasmids and host cells to be effectively selected and maintained without the use of antibiotics. An Escherichia coli strain carrying a defect in NAD de novo biosynthesis was constructed by knocking out the chromosomal quinolinic acid phosphoribosyltransferase (QAPRTase) gene. The resistance gene in the plasmids was replaced by the QAPRTase gene of E. coli or the mouse. As a result, only expression of the QAPRTase gene from plasmids can complement and rescue E. coli host cells in minimal medium. This is the first time that a vertebrate gene has been used to construct a nonantibiotic selection system, and it can be widely applied in DNA vaccine and gene therapy. As the QAPRTase gene is ubiquitous in species ranging from bacteria to mammals, the potential environmental biosafety problems caused by horizontal gene transfer can be eliminated.

Author(s):  
Dao-Ji Cen ◽  
Ruan-Yang Sun ◽  
Jia-Lin Mai ◽  
Yu-Wei Jiang ◽  
Dong Wang ◽  
...  

We investigated the prevalence and transmission of NDM-producing Enterobacteriaceae in fecal samples of geese and environmental samples from a goose farm in Southern China. The samples were cultivated on MacConkey agar plates supplemented with meropenem. Individual colonies were examined for blaNDM and blaNDM-positive bacteria were characterized based on WGS data from the Illumina and ONT platforms. Of 117 samples analyzed, the carriage rates for NDM-positive Enterobacteriaceae were 47.1, 18 and 50% in geese, inanimate environments (sewage, soil, fodder and dust) and mouse samples, respectively. Two variants (4 blaNDM-1 and 40 blaNDM-5) were found among 44 blaNDM-positive Enterobacteriaceae, which belonged to 8 species and Escherichia coli was the most prevalent (50%). WGS analysis revealed that blaNDM co-existed with diverse antibiotic resistance genes (ARGs). Population structure analysis showed that most E. coli and Enterobacter sp. isolates were highly heterogeneous while most Citrobacter sp. and P. stuartii isolates possessed extremely high genetic similarity. Additionally, blaNDM-5-positive ST4358/ST48 E. coli isolates were found to be clonally spread between the geese and environment and were highly genetically similar to those reported from ducks, farm environments and humans in China. Plasmid analysis indicated that IncX3 pHNYX644-1-like (n=40) and untypable pM2-1-like plasmids (n=4) mediated blaNDM spread. pM2-1-like plasmids possessed diverse ARGs including blaNDM-1, the arsenical and mercury resistance operons and the maltose operon. Our findings revealed that the goose farm is a reservoir for NDM-positive Enterobacteriaceae. The blaNDM contamination of wild mice and the novel pM2-1-like plasmid described in this study likely adds to the risk for dissemination of blaNDM and associated resistance genes. Importance: The carbapenem-resistant bacteria, in particular NDM-producing Enterobacteriaceae, has become a great threat to global public. These bacteria have been found not only in hospital and community environments, but also among food animal production chains, which are recognized as reservoirs for NDM-producing Enterobacteriaceae. However, the dissemination of NDM-producing bacteria in the waterfowl farm has been less well explored. Our study demonstrated that horizontal spread of blaNDM-carrying plasmids and the partial clonal spread of blaNDM-positive Enterobacteriaceae contributed to widespread contamination of blaNDM in the goose farm ecosystem, including mouse. Furthermore, we found a novel and transferable blaNDM-1-carrying MDR plasmid that possessed multiple environmental adaptation-related genes. The outcomes of this study contribute to a better understanding of the prevalence and transmission of blaNDM-producing Enterobacteriaceae among diverse niches in the farm ecosystem.


2018 ◽  
Vol 81 (8) ◽  
pp. 1339-1345 ◽  
Author(s):  
KAFEEL AHMAD ◽  
FARYAL KHATTAK ◽  
AMJAD ALI ◽  
SHAISTA RAHAT ◽  
SHAZIA NOOR ◽  
...  

ABSTRACT We report the prevalence of extended-spectrum β-lactamases and carbapenemases in Escherichia coli isolated from retail chicken in Peshawar, Pakistan. One hundred E. coli isolates were recovered from retail chicken. Antibiotic susceptibility testing was carried out against ampicillin, chloramphenicol, kanamycin, nalidixic acid, cephalothin, gentamicin, sulfamethoxazole-trimethoprim, and streptomycin. Phenotypic detection of β-lactamase production was analyzed through double disc synergy test using the antibiotics amoxicillin-clavulanate, cefotaxime, ceftazidime, cefepime, and aztreonam. Fifty multidrug-resistant isolates were screened for detection of sul1, aadA, cmlA, int, blaTEM, blaSHV, blaCTX-M, blaOXA-10, blaVIM, blaIMP, and blaNDM-1 genes. Resistance to ampicillin, nalidixic acid, kanamycin, streptomycin, cephalothin, sulfamethoxazole-trimethoprim, gentamicin, cefotaxime, ceftazidime, aztreonam, cefepime, amoxicillin-clavulanate, and chloramphenicol was 92, 91, 84, 73, 70, 67, 53, 48, 40, 39, 37, 36, and 23% respectively. Prevalence of sul1, aadA, cmlA, int, blaTEM, blaCTX-M, blaIMP, and blaNDM-1 was 78% (n = 39), 76% (n = 38), 20% (n = 10), 90% (n = 45), 74% (n = 37), 94% (n = 47), 22% (n = 11), and 4% (n = 2), respectively. blaSHV, blaOXA-10, and blaVIM were not detected. The coexistence of multiple antibiotic resistance genes in multidrug-resistant strains of E. coli is alarming. Hence, robust surveillance strategies should be developed with a focus on controlling the spread of antibiotic resistance genes via the food chain.


2019 ◽  
Vol 61 (1) ◽  
Author(s):  
Edgarthe Priscilla Ngaiganam ◽  
Isabelle Pagnier ◽  
Wafaa Chaalal ◽  
Thongpan Leangapichart ◽  
Selma Chabou ◽  
...  

Abstract Background We investigate here the presence of multidrug-resistant bacteria isolated from stool samples of yellow-legged gulls and chickens (n = 136) in urban parks and beaches of Marseille, France. Bacterial isolation was performed on selective media, including MacConkey agar with ceftriaxone and LBJMR medium. Antibiotic resistance genes, including extended-spectrum β-lactamases (ESBL) (i.e. blaCTX-M, blaTEM and blaSHV), carbapenemases (blaKPC, blaVIM, blaNDM, blaOXA-23, blaOXA-24, blaOXA-48 and blaOXA-58) and colistin resistance genes (mcr-1 to mcr-5) were screened by real-time PCR and standard PCR and sequenced when found. Results Of the 136 stools samples collected, seven ESBL-producing Gram-negative bacteria (BGN) and 12 colistin-resistant Enterobacteriaceae were isolated. Among them, five ESBL-producing Escherichia coli and eight colistin-resistant Hafnia alvei strains were identified. Four blaTEM-1 genes were detected in yellow-legged gulls and chickens. Three CTX-M-15 genes were detected in yellow-legged gulls and pigeons, and one CTX-M-1 in a yellow-legged gull. No mcr-1 to mcr-5 gene were detected in colistin-resistant isolates. Genotyping of E. coli strains revealed four different sequence types already described in humans and animals and one new sequence type. Conclusions Urban birds, which are believed to have no contact with antibiotics appear as potential source of ESBL genes. Our findings highlight the important role of urban birds in the proliferation of multidrug-resistant bacteria and also the possible zoonotic transmission of such bacteria from wild birds to humans.


2021 ◽  
Vol 9 (8) ◽  
pp. 1613
Author(s):  
Julian A. Paganini ◽  
Nienke L. Plantinga ◽  
Sergio Arredondo-Alonso ◽  
Rob J. L. Willems ◽  
Anita C. Schürch

The incidence of infections caused by multidrug-resistant E. coli strains has risen in the past years. Antibiotic resistance in E. coli is often mediated by acquisition and maintenance of plasmids. The study of E. coli plasmid epidemiology and genomics often requires long-read sequencing information, but recently a number of tools that allow plasmid prediction from short-read data have been developed. Here, we reviewed 25 available plasmid prediction tools and categorized them into binary plasmid/chromosome classification tools and plasmid reconstruction tools. We benchmarked six tools (MOB-suite, plasmidSPAdes, gplas, FishingForPlasmids, HyAsP and SCAPP) that aim to reliably reconstruct distinct plasmids, with a special focus on plasmids carrying antibiotic resistance genes (ARGs) such as extended-spectrum beta-lactamase genes. We found that two thirds (n = 425, 66.3%) of all plasmids were correctly reconstructed by at least one of the six tools, with a range of 92 (14.58%) to 317 (50.23%) correctly predicted plasmids. However, the majority of plasmids that carried antibiotic resistance genes (n = 85, 57.8%) could not be completely recovered as distinct plasmids by any of the tools. MOB-suite was the only tool that was able to correctly reconstruct the majority of plasmids (n = 317, 50.23%), and performed best at reconstructing large plasmids (n = 166, 46.37%) and ARG-plasmids (n = 41, 27.9%), but predictions frequently contained chromosome contamination (40%). In contrast, plasmidSPAdes reconstructed the highest fraction of plasmids smaller than 18 kbp (n = 168, 61.54%). Large ARG-plasmids, however, were frequently merged with sequences derived from distinct replicons. Available bioinformatic tools can provide valuable insight into E. coli plasmids, but also have important limitations. This work will serve as a guideline for selecting the most appropriate plasmid reconstruction tool for studies focusing on E. coli plasmids in the absence of long-read sequencing data.


Antibiotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 344
Author(s):  
Momna Rubab ◽  
Deog-Hwan Oh

Shiga toxin-producing Escherichia coli (STEC) is an enteric pathogen associated with human gastroenteritis outbreaks. Extensive use of antibiotics in agriculture selects resistant bacteria that may enter the food chain and potentially causes foodborne illnesses in humans that are less likely to respond to treatment with conventional antibiotics. Due to the importance of antibiotic resistance, this study aimed to investigate the combination of phenotypic and genotypic antibiotic resistance in STEC isolates belonging to serogroups O26, O45, O103, O104, O111, O121, O145, and O157 using disc diffusion and polymerase chain reaction (PCR), respectively. All strains were phenotypically resistant to at least one antibiotic, with 100% resistance to erythromycin, followed by gentamicin (98%), streptomycin (82%), kanamycin (76%), and ampicillin (72%). The distribution of antibiotic resistance genes (ARGs) in the STEC strains was ampC (47%), aadA1 (70%), ere(A) (88%), blaSHV (19%), blaCMY (27%), aac(3)-I (90%), and tet(A) (35%), respectively. The results suggest that most of the strains were multidrug-resistant (MDR) and the most often observed resistant pattern was of aadA1, ere(A), and aac(3)-I genes. These findings indicate the significance of monitoring the prevalence of MDR in both animals and humans around the globe. Hence, with a better understanding of antibiotic genotypes and phenotypes among the diverse STEC strains obtained, this study could guide the administration of antimicrobial drugs in STEC infections when necessary.


2020 ◽  
Author(s):  
ying tao ◽  
kaixin zhou ◽  
lianyan xie ◽  
yanping xu ◽  
lizhong han ◽  
...  

Abstract Background: Quinolones are commonly used for treatment of infections by bacteria of the Enterobacteriaceae family. However, the rising resistance to quinolones worldwide poses a major clinical and public health risk. This study aimed to characterise a novel multiple resistance plasmid carrying three plasmid-mediated quinolone resistance genes in Escherichia coli clinical stain RJ749. Methods: MICs of ceftriaxone, cefepime, ceftazidime, ciprofloxacin, and levofloxacin for RJ749 and transconjugant c749 were determined by the Etest method. Conjugation was performed using sodium azide-resistant E. coli J53 strain as a recipient. The quinolone resistance-determining regions of gyrA, gyrB, parC, and parE were PCR-amplified. Results: RJ749 was highly resistant to quinolones, while c749 showed low-level resistance. S1-nuclease pulsed-field gel electrophoresis revealed that RJ749 and c749 both harboured a plasmid. PCR presented chromosomal mutation sites of the quinolone resistance-determining region, which mediated quinolone resistance. The c749 genome comprised a single plasmid, pRJ749, with a multiple resistance region, including three plasmid-mediated quinolone resistance (PMQR) genes (aac(6′)-Ib-cr, qnrS2, and oqxAB) and ten acquired resistance genes. One of the genes, qnrS2, was shown for the first time to be flanked by two IS26s. Three IS26-mediated circular molecules carrying the PMQR genes were detected. Conclusions: We revealed the coexistence of three PMQR genes on a multiple resistance plasmid and a new surrounding genetic structure of qnrS2 flanked by IS26 elements. IS26 plays an important role in horizontal spread of quinolone resistance.


Author(s):  
Juan He ◽  
Cui Li ◽  
Pengfei Cui ◽  
Hongning Wang

Abstract Background: This study was aimed to investigate the prevalence and structure of Tn7-like in Enterobacteriaceae from livestock and poultry as well as their possible role as reservoir of antibiotic resistance genes (ARGs).Methods: Polymerase chain reaction (PCR) and DNA sequencing analyses were used for the characterization of Tn7-like, associated integrons and ARGs. The antimicrobial resistance profile of the isolates was examined by using disc diffusion test.Results: Three hundred and seventy-eight Tn7-like-positive strains of Enterobacteriaceae were isolated, and included E. coli (128), Proteus(150), K. pneumonia(17), Salmonella(13), M. morganii (21) and A. baumannii(1), wherein high resistance was observed for Trimethoprim/Sulfamethoxazole and Streptomycin, and fifty percent of the strains were multidrug-resistant. Integrons class 2 were detected in all of the isolates and there are high frequency mutation sites especially in 535, a stop mutation. Variable region of class 2 integrons carried same gene cassettes, namely aadA1-sat2-dfrA1. From the 378 isolated strains, we found a new type of Tn7-like on a plasmid, named Tn6765.Conclusions: These findings proved that the Tn7-like can contribute to the horizontal transmission of antibiotic resistant genes in livestock and poultry. As potential vessels for antibiotic resistance genes (ARGs), Tn7-like could not be ignored due to their efficient transfer ability in environments.


2021 ◽  
Vol 88 (1) ◽  
Author(s):  
Bo Yu ◽  
Yanan Zhang ◽  
Li Yang ◽  
Jinge Xu ◽  
Shijin Bu

This study was carried out to investigate the resistance phenotypes and resistance genes of Escherichia coli from swine in Guizhou, China. A total of 47 E. coli strains isolated between 2013 and 2018 were tested using the Kirby–Bauer (K–B) method to verify their resistance to 19 common clinical antimicrobials. Five classes consisting of 29 resistance genes were detected using polymerase chain reaction. The status regarding extended-spectrum β-lactamase (ESBL) and the relationship between ESBL CTX-M-type β-lactamase genes and plasmid-mediated quinolone resistance (PMQR) genes were analysed. A total of 46 strains (97.9%) were found to be multidrug resistant. Amongst them, 27 strains (57.4%) were resistant to more than eight antimicrobials, and the maximum number of resistant antimicrobial agents was 16. Twenty antibiotic resistance genes were detected, including six β-lactamase genes blaTEM (74.5%), blaCTX-M-9G (29.8%), blaDHA (17.0%), blaCTX-M-1G (10.6%), blaSHV (8.5%), blaOXA (2.1%), five aminoglycoside-modifying enzyme genes aac(3′)-IV (93.6%), aadA1 (78.7%), aadA2 (76.6%), aac(3′)-II c (55.3%), aac(6′)-Ib (2.1%) and five amphenicol resistance genes floR (70.2%), cmlA (53.2%), cat2 (10.6%), cat1 (6.4%), cmlB (2.1%), three PMQR genes qnrS (55.3%), oqxA (53.2%), qepA (27.7%) and polypeptide resistance gene mcr-1 (40.4%). The detection rate of ESBL-positive strains was 80.9% (38/47) and ESBL TEM-type was the most abundant ESBLs. The percentage of the PMQR gene in blaCTX-M-positive strains was high, and the detection rate of blaCTX-M-9G was the highest in CTX-M type. It is clear that multiple drug resistant E. coli is common in healthy swine in this study. Extended-spectrum β-lactamase is very abundant in the E. coli strains isolated from swine and most of them are multiple compound genotypes.


2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Beatus Lyimo ◽  
Joram Buza ◽  
Murugan Subbiah ◽  
Sylivester Temba ◽  
Honest Kipasika ◽  
...  

The aim of this study was to identify the replicon types of plasmids, conjugation efficiencies, and the complement of antibiotic resistance genes for a panel of multidrug resistantE. coliisolates from surface waters in northern Tanzania. Standard membrane filtration was used to isolate anduidAPCR was used to confirm the identity of strains asE. coli. Antibiotic susceptibility was determined by breakpoint assay and plasmid conjugation was determined by filter-mating experiments. PCR and sequencing were used to identify resistance genes and PCR-based replicon typing was used to determine plasmid types. Filter mating experiments indicated conjugation efficiencies ranged from 10−1to 10−7. Over 80% of the donor cells successfully passed their resistance traits and eleven different replicon types were detected (IncI1, FIC, P, FIIA, A/C, FIB, FIA, H12, K/B B/O, and N). IncF plasmids were most commonly detected (49% of isolates), followed by types IncI1 and IncA/C. Detection of these public health-relevant conjugative plasmids and antibiotic resistant traits in Tanzanian water suggests the possible pollution of these water sources from human, livestock, and wild animal wastes and also shows the potential of these water sources in the maintenance and transmission of these resistance traits between environments, animals, and people.


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