Antimicrobial Resistance Plasmid Research Articles

Inc A/C Plasmids Are Prevalent in Multidrug-Resistant Salmonella enterica Isolates

Bacterial plasmids are fragments of extrachromosomal double-stranded DNA that can contain a variety of genes that are beneficial to the host organism, like those responsible for antimicrobial resistance. The objective of this study was to characterize a collection of 437 Salmonella enterica isolates from different animal sources for their antimicrobial resistance phenotypes and plasmid replicon types and, in some cases, by pulsed-field gel electrophoresis (PFGE) in an effort to learn more about the distribution of multidrug resistance in relation to replicon types. A PCR-based replicon typing assay consisting of three multiplex PCRs was used to detect 18 of the 26 known plasmid types in the Enterobacteriaceae based on their incompatibility (Inc) replicon types. Linkage analysis was completed with antibiograms, replicon types, serovars, and Inc A/C. Inc A/C plasmids were prevalent in multidrug-resistant isolates with the notable exception of Salmonella enterica serovar Typhimurium. Cluster analysis based on PFGE of a subset of 216 isolates showed 155 unique types, suggesting a variable population, but distinct clusters of isolates with Inc A/C plasmids were apparent. Significant linkage of serovar was also seen with Inc replicon types B/O, I1, Frep, and HI1. The present study showed that the combination of Salmonella, the Inc A/C plasmids, and multiple-drug-resistant genes is very old. Our results suggest that some strains, notably serovar Typhimurium and closely related types, may have once carried the plasmid but that the resistance genes were transferred to the chromosome with the subsequent loss of the plasmid.

Quinolones Resistance And R-Plasmids Of Clinical Isolates Of <i>Pseudomonas</i> Species

Background: There has been reported incidence in the emergence of Quinolones resistance in clinical isolates in Nigeria and the level in resistance has been on the increase. Objective: To determine the antimicrobial resistance patterns and plasmids profiles of 67 clinical Pseudomonas species from a teaching hospital and diagnostic laboratory in Nigeria. Materials and methods: The Pseudomonas species were identified and confirmed by standard procedures. The antibiotic susceptibility patterns were determined by Agar Disk Diffusion method. Plasmids DNA was isolated, separated and stained as previously described. Results: 30 of these clinical isolates were found to be resistant to 6 quinolones antibiotics with ciprofloxacin being the highest [52.24%] and norfloxacin [38.81%] the lowest. All the strains that were resistant to any antimicrobial agents were also resistant to ciprofloxacin. A total of 54 plasmids ranging in molecular sizes from 3.55kb to 19.95kb were extracted from the resistant strains and grouped into 5 plasmid profiles. Transformation experiment revealed that 66.67% of the resistant strains carried a common R plasmid of size 15.85kb. Plasmid –mediated resistant to ciprofloxacin and levofloxacin were found. Conclusion: The results highlighted diverse plasmids profile and wide spread antimicrobial resistance patterns of some clinical Pseudomonas species from Nigeria. Keywords : Quinolones, R-plasmids, Pseudomonas . Sudan Journal of Medical Sciences Vol. 3 (2) 2008: pp. 139-146

Transfer of antimicrobial resistance plasmids from Klebsiella pneumoniae to Escherichia coli in the mouse intestine

Objectives and methodsKlebsiella pneumoniae is a nosocomial pathogen and is considered the most common Gram-negative bacterium that exhibits multiple antimicrobial resistances. In this study, the transfer of antimicrobial resistance genes from the clinical multiresistant K. pneumoniae MGH75875 isolate was assessed in vitro and in vivo in an intestinal colonization animal model. The ability to colonize and transfer was tested under different antimicrobial treatments. The frequency of the horizontal gene transfer was also examined in vitro.ResultsThe clinical isolate of K. pneumoniae colonized the intestine of mice at levels up to 109 cfu/g faeces in antimicrobial-treated mice. In mice without antimicrobial treatment, the strain quickly decreased to below the detection limit due to competitive exclusion by the indigenous mouse flora. Onset of antimicrobial treatment gave immediate rise to detectable levels of the strain in the faeces of up to 109 cfu/g faeces. The experiment clearly shows that the treatment selects resistant strains and gives advantages to colonize the gastrointestinal tract. Furthermore, high transfer frequency of different plasmids was observed during colonization of the mouse intestine. The blaSHV and blaTEM genotypes were transferred to both an indigenous recipient in the in vivo setting and to an MG1655 Escherichia coli recipient strain in vitro.ConclusionsK. pneumoniae is an excellent colonizer of the intestine and is extremely promiscuous with respect to the transferability of its numerous plasmids. Antimicrobial treatment enhances the selection of resistant strains and results in an increase in the resistance gene pool, which ultimately raises the risk of spreading resistance genes.

Antimicrobial resistance and plasmid profiles of urinary Escherichia coli isolates from Jordanian patients

We investigated antimicrobial resistance patterns and plasmid profiles of uropathogenic Escherichia coli isolates from inpatients and outpatients at Jordan University Hospital in 2000 and 2001. E. coli accounted for 32.4% and 37.4% of all isolates respectively. The lowest susceptibility was for ampicillin (11%), cotrimoxazole (23%) and tetracycline (26%). The relative incidence of resistant isolates of E. coli to nalidixic acid, gentamicin, norfloxacin, cefuroxime and nitrofurantoin was significantly greater for inpatients than for outpatients (P< 0.05). A large, transferable R-plasmid of 28 kb was found in most E. coli isolates (67%) that were resistant to at least ampicillin, cotrimoxazole and tetracycline. This R-plasmid reservoir may contribute to the spread of multiple antibiotic resistance in our Region.

Molecular analysis of incHI1 antimicrobial resistance plasmids from Salmonella serovar Typhi strains associated with typhoid fever.

The first outbreak of multidrug-resistant (MDR) typhoid fever in Vietnam was in 1993, and by 1995 nearly 90% of cases were MDR. Plasmid HCM1, sequenced in full, is an incHI1 plasmid from Salmonella enterica serovar Typhi strain CT18, isolated in Vietnam in 1993. Restriction analysis shows that pHCM1 shares a restriction fragment length polymorphism (RFLP) pattern with plasmids isolated from the first outbreak and 10 of 17 MDR plasmids isolated from sporadic cases occurring at the same time in Vietnam. A core region of pHCM1 has significant DNA sequence similarity to plasmid R27, isolated in 1961 from S. enterica in the United Kingdom. There are five regions of DNA in pHCM1 which are not present in R27. Two of these are putative acquisition regions; the largest is 34.955 kbp in length and includes sequences of several antibiotic resistance genes and several insertion sequences. The borders of this region are defined by two identical IS10 left elements, associated with an inversion of DNA or with a truncated Tn10 element. The second, smaller region is 14.751 kbp and carries a trimethoprim resistance gene dfr14A cassette associated with a class 1 integrase. In 1993 to 1994, restriction analysis revealed some variations in the structures of Salmonella serovar Typhi MDR plasmids which were mapped to the two putative acquisition regions and three smaller variable regions. In 1996 a single RFLP type, RFLP7, was found to carry the dfrA7 and sul-1 genes, which were not present on R27 or pHCM1. This plasmid type appears to have a selective advantage over other plasmids with the same resistance phenotype.

Antimicrobial susceptibility and plasmid analysis of Actinobacillus pleuropneumoniae isolated in Taiwan

Sixty Actinobacillus pleuropneumoniae (App) strains from pigs in Taiwan were examined. Serotyping revealed that these belonged to serovars 1 ( n=53), 2 ( n=3), and 5 ( n=4). Agar disk diffusion susceptibility testing of the isolates showed 55 (92%) were resistant to three or more antimicrobial agents. Six resistance patterns were observed. Ampicillin–chloramphenicol–flumequine–nalidixic acid–streptomycin–sulfonamide/trimethoprim–tetracycline was the most common multi-resistance pattern. Minimal inhibitory concentration of 14 antimicrobial agents was determined. The isolates were highly susceptible to ceftiofur and trimethoprim in vitro. Isolates were resistant to streptomycin, ampicillin, and nalidixic acid. All isolates were examined for the presence of plasmids using the alkaline lysis method. Forty three (72%) isolates had four plasmid bands with an approximate sizes of 3.5, 4.3, 5.8 and 6.0 kb; 12 (20%) had three bands at 3.5, 4.3 and 5.2 kb, and 5 (8%) had no plasmid bands. Antimicrobial resistance plasmids were detected in resistant strains of App. Three antimicrobial resistance plasmids were transformed into E. coli DH5α. pTMY1 (4.3 kb) encoded a streptomycin kinase and a dihydropteroate synthase; pTMY2 (6.0 kb) encoded ROB-1 β-lactamase and aminoglycoside 3′-phosphotransferase; pTMY3 (5.2 kb) encoded only ROB-1 β-lactamase. The 4.3 kb plasmid was sequenced and consisted of 4242 bp with 42.9% GC content. The 4.3 kb plasmid DNA sequence was 98% homologous to a plasmid previously isolated from Pasteurella haemolytica.

Molecular epidemiology of Salmonella Heidelberg in an equine hospital

From 1992 to 1997, multi-drug resistant (MDR) Salmonella Heidelberg isolates were cultured from a number of horses hospitalised in a veterinary hospital in Victoria, Australia. To examine the relationships between the cases, 28 isolates from the hospital were compared by pulsed field gel electrophoresis (PFGE), IS 200 element profiles, antimicrobial resistance patterns, plasmid profiles and phage typing. The PFGE patterns following digestion with XbaI and BlnI restriction endonucleases showed that the isolates from the veterinary hospital originated from a common source. These isolates also had indistinguishable IS 200 profiles. However, PFGE was more discriminatory than IS 200 profiles. All the veterinary hospital isolates and one independent isolate had the same antimicrobial resistance pattern and had at least one plasmid in common. Localisation of antimicrobial resistance genes indicated that the veterinary hospital isolates had more than one plasmid carrying resistance genes and that the genes encoding sulphathiazole and trimethoprim resistance were not on these plasmids. Phage typing was ineffective as 22 of the 28 isolates were untypeable. In conclusion, the combination of different methods used for epidemiological studies suggested that a single strain of MDR S. Heidelberg was isolated from horses admitted to the hospital for 6 years and caused salmonellosis in susceptible horses within that period with no apparent correlation between the antimicrobials used and retention of its MDR phenotype.

Identification and characterization of Arcobacter isolates from broilers by biochemical tests, antimicrobial resistance patterns and plasmid analysis.

A total of 89 Arcobacter butzleri isolates obtained from freshly slaughtered broilers was investigated for their biochemical capacities by using the API CAMPY system as well as additional growth and tolerance tests, for their antimicrobial resistance patterns and their plasmid content. Among these techniques, biochemical profiling and antimicrobial resistance testing proved to be the most discriminatory methods as confirmed by the calculation of discriminatory indices. These two methods might represent valuable tools for epidemiological analysis of A. butzleri isolates. Small plasmids of up to 5 kbp were detectable in only 21 of the 89 isolates while the remaining 68 A. butzleri isolates were plasmid-free.

Antimicrobial resistance pattern and plasmid profile of Salmonella typhi isolated from an outbreak in Tehran province.

The antimicrobial resistance patterns and plasmid profiles of Salmonella typhi isolates from sporadic cases (n = 33) and an outbreak (n = 48) were compared. Of 28 sporadic drug-resistant isolates, 24 (85.7%) were multiply resistant. The predominant antibiotic resistance pattern was TeCmSmSxTAp, which was also the most common pattern of the outbreak isolates. 13 drug-resistant strains isolated before the outbreak (46.4%) were able to transfer the whole resistance pattern or part of it to Escherichia coli K 12 by conjugation. Although 20 of the sporadic strains contained plasmid DNA, transferable R plasmids were only detected in 13 (65%) of them. Among the outbreak strains, the rate of R plasmid transfer was 92.3%, with only the TeCmSmSxTAp pattern transferred. Plasmid profiling and Hind III endonuclease digestion of plasmid DNA identified a 91.2 megadaltons (Mda) plasmid that was recovered from most of the outbreak isolates and from 4 strains collected before the outbreak. This plasmid coded for TeCmSmSxtAp and transferred the pattern of resistance in toto. The results indicate multidrug-resistant S. typhi as a potential cause of infection in the region.

Biochemical characterisation, enteropathogenicity and antimicrobial resistance plasmids of clinical and environmental Aeromonas isolates.

One hundred and eight strains of Aeromonas from clinical and environmental samples were speciated. Seven species were identified, the most prevalent of which was A. hydrophila. Experimental studies in an animal model with 36 representative strains of different species revealed that all strains could cause significant fluid accumulation in rabbit ileal loops. Of 107 strains showing single or multiple antimicrobial resistance, the highest incidence of resistance was shown for beta-lactam antibiotics other than cefotaxime. Transferable resistance plasmids, encoding resistance to ampicillin, cephalexin, cefoxitin, erythromycin and furazolidone, either alone or in combination, were detected in 35 strains. A further proportion of strains could be cured of one or more resistance markers, including resistance to nalidixic acid, and this was accompanied by the loss of plasmid DNA. The plasmids ranged in size between 85.6 and > 1 50 kb.

Antibiotic resistance patterns and plasmid profiles for Shigella spp. isolated in Cordoba, Argentina.

The antimicrobial resistance patterns and plasmid profile analyses for 30 Shigella spp. isolated in Cordoba, Argentina, were determined. Most strains were resistant to multiple antibiotics, particularly traditional agents such as ampicillin, chloramphenicol and trimethoprim. All isolates harboured at least one plasmid (range 1-12), the plasmid profiles differing in every case. Nineteen strains transferred all or some of their resistance determinants by conjugation.

Association of carboxylesterase B electrophoretic pattern with presence and expression of urovirulence factor determinants and antimicrobial resistance among strains of Escherichia coli that cause urosepsis

We determined the carboxylesterase B electrophoretic profiles of 74 blood isolates of Escherichia coli from patients with urosepsis. Most strains (64%) exhibited the B2 electrophoretic pattern. P fimbrial and hemolysin genetic determinants were present and expressed significantly more often among strains with the B2 than with the B1 electrophoretic pattern. In contrast, aerobactin determinants were significantly more prevalent and more commonly expressed among the B1 strains; this difference was attributable to the presence of plasmid-encoded aerobactin in one-third of the B1 strains (P = 0.02, B1 versus B2). The prevalence and extent of antimicrobial resistance was significantly greater among the B1 strains, and the B1 electrophoretic pattern was more often found in isolates from patients with urinary tract abnormalities. We conclude that the carboxylesterase B electrophoretic pattern differentiates two groups of E. coli isolates from patients with urosepsis: strains with the B1 electrophoretic pattern are associated with urologically impaired hosts, characteristically lack P fimbrial and hemolysin determinants, and often carry a plasmid-encoded aerobactin system (possibly on multiple antimicrobial resistance plasmids), whereas B2 strains more commonly invade noncompromised hosts, express P fimbriae and hemolysin, carry chromosomal aerobactin determinants, and lack antimicrobial resistance.

SHIGELLA DYSENTERIAE TYPE 1 INFECTIONS IN US TRAVELLERS TO MEXICO, 1988

In 1988, the number of Shigella dysenteriaetype 1 (Sd1) infections reported in the USA increased five-fold over the annual mean from the previous decade. 44 (94%) of 47 interviewed patients reported recent travel to Mexico; 33 (75%) of these had been tourists to the Yucatan peninsula. 27 patients who had travelled to Mexico were admitted to hospital, of whom 2 had a haemolytic uraemic syndrome; none died. The antimicrobial resistance pattern and plasmid profile of the Yucatan strain were similar to those of the 1969-72 pandemic strain. Antimicrobial resistances and plasmid profiles were different in sporadic Western hemisphere strains. This is the first outbreak of Sdl among US tourists and it is the largest known outbreak in the Western hemisphere since the early 1970s. The dominant Sd1 strain is similar to that which caused the catastrophic 1969-72 pandemic. Surveillance and control measures have been instituted in the Yucatan peninsula.

Antimicrobial resistance patterns and plasmids of enteropathogenic Escherichia coli isolated in Nigeria.

In an epidemiological study of enteropathogenic Escherichia coli, 102 strains were isolated from patients seen at the University Teaching Hospital in Lagos. The most common serotype encountered was 055 followed by 026. Antimicrobial susceptibility testing and plasmid profiling of the strains were done. All the strains were sensitive to colistin, nalidixic acid, nitrofurantoin, cefotaxime, amikacin, and augmentin. Of the 102 strains, 47 (46%) were resistant to one or more of the following antimicrobial agents: Co-trimoxazole, tetracycline, ampicillin, streptomycin, sulphonamide and a combination of ampicillin with sulbactam. All the strains that were resistant to any antimicrobial agents were also resistant to tetracycline. Seventy-two strains (70.6%) harbored plasmid whose molecular weights ranged from 0.8 to 120 x 10(6) daltons. The majority of the plasmid were smaller than 6 x 10(6); 90% of strains carrying plasmid ranging in size from 2 to 6 x 10(6) daltons and 50 to 70 x 10(6) daltons were resistant to one or more antimicrobial agents. Transformation and conjugation experiment showed that about 57% of the resistant strains carried R plasmid. Plasmid-determined resistance to tetracycline, ampicillin, streptomycin and sulphonamide was found.

Contribution of the traT gene to serum resistance among clinical isolates of enterobacteriaceae.

Antimicrobial resistance plasmids containing the traT gene confer resistance to serum bactericidal activity upon some laboratory strains of Escherichia coli. We have examined the DNA of Enterobacteriaceae from human extraintestinal infections to determine the frequency of traT-like genes. DNA sequences homologous with traT were found among 58% of Escherichieae but among none of the Klebsielleae or Proteeae tested and were found as frequently among serum-sensitive E. coli as among serum-resistant strains. Sequences related to traT were always associated with large plasmids. The potential contribution of traT-containing plasmids to serum resistance of clinical isolates is discussed.

Antimicrobial resistance and resistance plasmids in Salmonella from Ontario, Canada

Collections of 589 human and 204 animal strains of Salmonella isolated in Ontario during the summer of1974 were examined for susceptibility to 12 antimicrobial agents. Many isolates were found to be resistant to both chloramphenicol (12.4% of the human and 38.2% of the animal sample) and ampicillin. The chloramphenicol resistance almost always occurred in strains which were also resistant to ampicillin and was usually due to a self-transmissible plasmid with a resistance pattern of CmKmSmTc (chloramphenicol, kanamycin, streptomycin, and tetracycline) or CmTc. Ampicillin resistance in these strains was mediated by a variety of plasmids with patterns ApSu (ampicillin and sulfa drugs) and ApSmSu, many of which were nonself-transmissible. Ampicillin resistance in chloramphenicol-sensitive strains was transferable from 21% of the strains, and it was associated with resistance patterns which were different from the self-transferable ampicillin patterns from the chloramphenicol-resistance strains.

Real Tennis Elbow

<h3>Abstract</h3> Increased colonisation by antimicrobial resistant organisms is closely associated with international travel. This study investigated the diversity of mobile genetic elements involved with antimicrobial resistance (AMR) gene carriage in extended-spectrum beta-lactamase (ESBL) -producing <i>Escherichia coli</i> that colonised travellers to Laos. Long-read sequencing was used to reconstruct complete plasmid sequences from 49 isolates obtained from the daily stool samples of 23 travellers over a three-week period. This method revealed a collection of 105 distinct plasmids, 38.1% of which carried AMR genes. The plasmids in this population were diverse, mostly unreported and included 38 replicon types, with F-type plasmids (n=22) the most prevalent amongst those carrying AMR genes. Fine-scale analysis of all plasmids identified numerous AMR gene contexts and emphasised the importance of IS elements, specifically members of the IS<i>6</i>/IS<i>26</i> family, in the creation of complex multi-drug resistance regions. We found a concerning convergence of ESBL and colistin resistance determinants, with three plasmids from two different F-type lineages carrying <i>bla</i>_CTX-M and <i>mcr</i> genes. The extensive diversity seen here highlights the worrying probability that stable new vehicles for AMR will evolve in <i>E. coli</i> populations that can disseminate internationally through travel networks. <h3>Impact Statement</h3> The global spread of AMR is closely associated with international travel. AMR is a severe global concern and has compromised treatment options for many bacterial pathogens, among them pathogens carrying ESBL and colistin resistance genes. Colonising MDR organisms have the potential to cause serious consequences. Infections caused by MDR bacteria are associated with longer hospitalisation, poorer patient outcomes, greater mortality, and higher costs compared to infections with susceptible bacteria. This study elucidates the numerous different types of plasmids carrying AMR genes in colonising ESBL-producing <i>E. coli</i> isolates found in faecal samples from in travellers to Vientiane, Laos. Here we add to known databases of AMR plasmids by adding these MDR plasmids found in Southeast Asia, an area of high AMR prevalence. We characterised novel AMR plasmids including complex ESBL (<i>bla</i>_CTX-M) and colistin (<i>mcr</i>) resistance co-carriage plasmids, emphasising the potential exposure of travellers to Laos to a wide variety of mobile genetic elements that may facilitate global AMR spread. This in-depth study has revealed further detail of the numerous factors that may influence AMR transfer, therefore potential routes of AMR spread internationally, and is a step towards finding methods to combat AMR spread. <h3>Data Summary</h3> Long-read sequencing data is available through National Center for Biotechnology Information under the BioProject PRJNA853172. Complete plasmid sequences have been uploaded to GenBank with accession numbers in supplementary S1. The authors confirm all supporting data, code and protocols have been provided within the article or through supplementary data files.