This study aimed to determine the epidemiology and association of antimicrobial resistance (AMR) among Escherichia coli and Salmonella in Thailand. The E. coli (n = 1047) and Salmonella (n = 816) isolates from pigs, pork and humans were screened for 18 replicons including HI1, HI2, I1-γ, X, L/M, N, FIA, FIB, W, Y, P, FIC, A/C, T, FIIAs, F, K and B/O using polymerase chain reaction-based replicon typing. The E. coli (n = 26) and Salmonella (n = 3) isolates carrying IncF family replicons, ESBL and/or mcr genes were determined for FAB formula. IncF represented the major type of plasmids. Sixteen and eleven Inc groups were identified in E. coli (85.3%) and Salmonella (25.7%), respectively. The predominant replicon patterns between E. coli and Salmonella were IncK-F (23.7%) and IncF (46.2%). Significant correlations (P < 0.05) were observed between plasmid-replicon type and resistance phenotype. Plasmid replicon types were significantly different among sources of isolates and sampling periods. The most common FAB types between E. coli and Salmonella were F2:A-:B- (30.8%) and S1:A-:B- (66.7%), respectively. In conclusion, various plasmids present in E. coli and Salmonella. Responsible and prudent use of antimicrobials is suggested to reduce the selective pressures that favour the spread of AMR determinants. Further studies to understand the evolution of R plasmids and their contribution to the dissemination of AMR genes are warranted.

A total of 180 non-duplicate carbapenem-resistant Klebsiella pneumoniae isolates were recovered from patients hospitalized between December 2010 and January 2012 at a Chinese hospital. Eight KPC-2, four NDM-1, one VIM-2, and five KPC-2 plus IMP-4 producers were identified and all were multidrug resistant due to the presence of other resistance determinants, including extended-spectrum β-lactamases (CTX-M-15, SHV-12), 16S rRNA methylases (armA, rmtB) and plasmid-mediated quinolone-resistance determinants (qnrA, B, S, aac(6′)-Ib-cr). Nine K. pneumoniae clones (Kpn-A1/ST395, Kpn-A3/ST11, Kpn-A2/ST134, Kpn-B/ST263, Kpn-C/ST37, Kpn-D/ST39, Kpn-E/ST1151, Kpn-F/ST890, Kpn-G/ST1153) were identified. bla KPC-2 was located on transferable ~65 kb IncL/M (ST395, ST11, ST134, ST39) and ~100 kb IncA/C (ST37, ST1153, ST890) plasmids, respectively. On the other hand, bla NDM-1 was associated with a ~70 kb IncA/C plasmid (ST263). However, non-typable plasmids of ~40 kb containing bla VIM-2 were detected in the ST1151 clone. This work reports the first co-occurrence of four diverse types of carbapenemase of K. pneumoniae clones from a single hospital in China. IncA/C, IncL/M, and other successful plasmids may be important for the dissemination of carbapenemases, producing a complex epidemiological picture.

Patients with Duchenne muscular dystrophy (DMD), an X-linked lethal muscle-wasting disease, have abnormal expression of the protein dystrophin within their muscle fibres. In the mdx mouse model of this condition, both germline and neonatal somatic gene transfers of dystrophin cDNAs have demonstrated the potential of gene therapy in treating DMD. However, in many DMD patients, there appears to be no dystrophin expression when muscle biopsies are immunostained or western blots are performed. This raises the possibility that the expression of dystrophin following gene transfer might trigger a destructive immune response against this ‘neoantigen’. Immune responses can also be generated against the gene transfer vector used to transfect the dystrophic muscle, and the combined immune response could further damage the already inflamed muscle. These problems are now beginning to be investigated in immunocompetent mdx mice. Although much work remains to be done, there are promising indications that these immune responses might not prove as much of a concern as originally envisaged.

The prospect of the deliberate environmental release of genetically manipulated microorganisms has given rise to a great deal of polemic. Amongst the rational scientific concerns are those concerned with the fate of the released bacteria, the fate of the recombinant genes that they carry, the selective pressures acting upon them in different environmental situations and the long term effects on the environment and human health. All recombinant DNA is carried by vectors (plasmids, transposons or bacteriophage or remnants of these). Thus the way in which recombinant constructions are made may itself lead to potential biosafety concerns, irrespective of the host bacterium and the recombinant DNA fragment of primary interest. The purpose of the present review is to assess progress in improved vector design aimed at eliminating risks due to the way recombinant vectors are constructed. Improved vector constructions include the avoidance of the use, or removal, of antibiotic resistance genes, the use of defective transposons rather than plasmids in order to reduce horizontal transfer and the development of conditionally lethal suicide systems. More recently, new site-specific recombination systems have permitted transposon vectors to be manipulated following strain construction, but before environmental release, so that virtually all recombinant DNA not directly involved in the release experiment is eliminated. Such bacteria are thus pseudo-wild type in that they contain no heterologous DNA other than the genes of interest.