Dissemination of mcr-1-Carrying Plasmids among Colistin-Resistant Salmonella Strains from Humans and Food-Producing Animals in Taiwan.

We detected the colistin resistance gene mcr-1 in four Salmonella serovars isolated from humans and animals with diarrhea. The resistance gene was carried on different plasmids. One mcr-1-carrying conjugative plasmid, a variant of pHNSHP45, was disseminated among Salmonella isolates recovered from humans, pigs, and chickens.

KEAP1 E3 ligase-mediated downregulation of NF-kappaB signaling by targeting IKKbeta.

IkappaB kinase beta (IKKbeta) is involved in tumor development and progression through activation of the nuclear factor (NF)-kappaB pathway. However, the molecular mechanism that regulates IKKbeta degradation remains largely unknown. Here, we show that a Cullin 3 (CUL3)-based ubiquitin ligase, Kelch-like ECH-associated protein 1 (KEAP1), is responsible for IKKbeta ubiquitination. Depletion of KEAP1 led to the accumulation and stabilization of IKKbeta and to upregulation of NF-kappaB-derived tumor angiogenic factors. A systematic analysis of the CUL3, KEAP1, and RBX1 genomic loci revealed a high percentage of genome loss and missense mutations in human cancers that failed to facilitate IKKbeta degradation. Our results suggest that the dysregulation of KEAP1-mediated IKKbeta ubiquitination may contribute to tumorigenesis.

Complete sequences of two plasmids in a blaNDM-1-positive Klebsiella oxytoca isolate from Taiwan.

Genetic determinants of a bla(NDM-1)-positive, multidrug-resistant bacterial isolate that caused active infection was investigated by DNA sequencing. Two plasmids, pKOX_NDM1 and pKOX-R1, were identified for the Klebsiella oxytoca strain E718. Sequence annotation revealed a bla(NDM-1) gene in pKOX_NDM1 and two extended-spectrum ß-lactamase producers (bla(CTX-M-3) and blaSHV-12) and a wide array of resistance genes in pKOX-R1. These findings highlight the difficulty in treating multidrug-resistant bacterial infections and the potential danger of emerging resistant enterobacteria.

Complete genome sequence of Klebsiella pneumoniae 1084, a hypermucoviscosity-negative K1 clinical strain.

We report the complete genome sequence of Klebsiella pneumoniae 1084, a hypermucoviscosity-negative K1 clinical strain. Sequencing and annotation revealed a 5,386,705-bp circular chromosome (57.4% G+C content), which contains 4,962 protein-coding genes, 80 tRNA genes, and 25 rRNA genes.

Complete genome sequence of Staphylococcus aureus M013, a pvl-positive, ST59-SCCmec type V strain isolated in Taiwan.

We report the complete genome sequence of M013, a representative strain of a pvl-positive, sequence type 59-staphylococcal cassette chromosome mec type V (ST59-SCCmec type V) community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) clone in Taiwan. Comparison of M013 with the genomes of two CA-MRSA strains in the United States revealed major differences in the regions covering several genomic islands and prophages.

Complete genome sequence of Klebsiella oxytoca E718, a New Delhi metallo-ß-lactamase-1-producing nosocomial strain.

We report the complete genome sequence of Klebsiella oxytoca E718, a New Delhi metallo-ß-lactamase-1 (NDM-1)-producing strain isolated from a renal transplant patient. The genome contains a 6,097,032-bp chromosome and two multidrug resistance plasmids with sizes of 324,906 bp and 110,781 bp.

Cardiac Fas-dependent and mitochondria-dependent apoptosis in ovariectomized rats.

BACKGROUND: Very limited information has been published regarding cardiac apoptosis in menopausal women or in those after bilateral oophorectomy. The purpose of this study was to evaluate whether cardiac Fas-dependent (type I) and mitochondria-dependent (type II) apoptotic pathways are activated in ovariectomized rats. METHODS: Thirty-two female Wistar rats at 6-7 months of age were randomly divided into sham-operated group (Sham) and bilateral ovariectomized group (OVX). Two months after the operation, the cardiac characteristics, myocardial architecture, and two major apoptotic pathways in the excised left ventricle from rats were measured by histopathological analysis, Western blotting and reverse transcription polymerase chain reaction (RT-PCR), and positive TUNEL assays. RESULTS: The whole heart weight, the left ventricular weight, the ratios of whole heart weight to tibia length, and the ratios of left ventricle to tibia length were significantly increased in OVX relative to Sham. Abnormal myocardial architecture, enlarged interstitial spaces, more minor cardiac fibrosis, and more cardiac TUNEL-positive apoptotic cells were observed in OVX. The key components of Fas-dependent apoptosis (TNF-alpha, Fas ligand, Fas death receptors, Fas-associated death domain (FADD), activated caspase 8, and activated caspase 3) and key components of mitochondria-dependent apoptosis (Bad, Bax, Bax-to-Bcl2 ratio, cytosolic cytochrome c, activated caspase 9, and activated caspase 3) were significantly increased in OVX hearts. CONCLUSIONS: The absence of female ovaries will activate the cardiac Fas-dependent and mitochondria-dependent apoptotic pathways, which might provide one of possible mechanism for developing heart failure in post-menopause women.

Prevalence and characteristics of pks genotoxin gene cluster-positive clinical Klebsiella pneumoniae isolates in Taiwan.

The pks gene cluster encodes enzymes responsible for the synthesis of colibactin, a genotoxin that has been shown to induce DNA damage and contribute to increased virulence. The present study investigated the prevalence of pks in clinical K. pneumoniae isolates from a national surveillance program in Taiwan, and identified microbiological and molecular factors associated with pks-carriage. The pks gene cluster was detected in 67 (16.7%) of 400 isolates from various specimen types. Multivariate analysis revealed that isolates of K1, K2, K20, and K62 capsular types (p < 0.001), and those more susceptible to antimicrobial agents (p = 0.001) were independent factors strongly associated with pks-carriage. Phylogenetic studies on the sequence type (ST) and pulsed-field gel electrophoresis patterns indicated that the pks-positive isolates belong to a clonal group of ST23 in K1, a locally expanding ST65 clone in K2, a ST268-related K20 group, and a highly clonal ST36:K62 group. Carriage of rmpA, iutC, and ybtA, the genes associated with hypervirulence, was significantly higher in the pks-positive isolates than the pks-negative isolates (95.5% vs. 13.2%, p < 0.001). Further studies to determine the presence of hypervirulent pks-bearing bacterial populations in the flora of community residents and their association with different disease entities may be warranted.

Therapeutic effects of Dioscorea on post-menopause-induced cardiac apoptosis in rats.

OBJECTIVE: To evaluate the effects of Dioscorea on bilateral ovariectomies-induced cardiac Fasdependent and mitochondria-dependent apoptotic pathways. METHODS: Forty-eight female Wistar rats at 6-7 months of age were equally divided into a sham-operated group, and a bilateral ovariectomized (OVX) group for 2 months, and the rats in the OVX group were further fed with 0, 250 or 750 mL/kg Dioscorea spp. daily in the 2nd month. The excised hearts were measured by positive terminal deoxynucleotidyltransferase UTP nick end labeling (TUNEL) assays, western blotting and reverse transcription-polymerase chain reaction. RESULTS: Dioscorea spp. decreased OVX-induced cardiac TUNEL-positive apoptotic cells; decreased OVX-induced TNF-alpha, Fas ligand, Fas death receptors, Fas-associated death domain, activated caspase-8, and -3 (Fas pathways); decreased OVX-induced Bad, Bax, Bax-to-Bcl2 ratio, activated caspase-9, and -3 (mitochondria pathway). CONCLUSIONS: Dioscorea spp. prevented ovariectomy-induced cardiac Fas-dependent and mitochondriadependent apoptotic pathways in rat models. The fifi ndings may provide possible therapeutic effects of dioscorea for potentially preventing cardiac apoptosis after ovariectomy or post-menopause.

Genotoxic Klebsiella pneumoniae in Taiwan.

BACKGROUND: Colibactin is a nonribosomal peptide-polyketide synthesized by multi-enzyme complexes encoded by the pks gene cluster. Colibactin-producing Escherichia coli have been demonstrated to induce host DNA damage and promote colorectal cancer (CRC) development. In Taiwan, the occurrence of pyogenic liver abscess (PLA) has been suggested to correlate with an increasing risk of CRC, and Klebsiella pneumoniae is the predominant PLA pathogen in Taiwan. METHODOLOGY/PRINCIPAL FINDINGS: At the asn tRNA loci of the newly sequenced K. pneumoniae 1084 genome, we identified a 208-kb genomic island, KPHPI208, of which a module identical to the E. coli pks colibactin gene cluster was recognized. KPHPI208 consists of eight modules, including the colibactin module and the modules predicted to be involved in integration, conjugation, yersiniabactin production, microcin production, and unknown functions. Transient infection of BALB/c normal liver cells with K. pneumoniae 1084 increased the phosphorylation of histone H2AX, indicating the induction of host DNA damage. Colibactin was required for the genotoxicity of K. pneumoniae 1084, as it was diminished by deletion of clbA gene and restored to the wild type level by trans-complementation with a clbA coding plasmid. Besides, BALB/c mice infected with K. pneumoniae 1084 exhibited enhanced DNA damage in the liver parenchymal cells when compared to the isogenic clbA deletion mutant. By PCR detection, the prevalence of pks-positive K. pneumoniae in Taiwan is 25.6%, which is higher than that reported in Europe (3.5%), and is significantly correlated with K1 type, which predominantly accounted for PLA in Taiwan. CONCLUSIONS: Our knowledge regarding how bacteria contribute to carcinogenesis has just begun. The identification of genotoxic K. pneumoniae and its genetic components will facilitate future studies to elucidate the molecular basis underlying the link between K. pneumoniae, PLA, and CRC.

Copy Number Change of the NDM-1 sequence in a multidrug-resistant Klebsiella pneumoniae clinical isolate.

The genetic features of the antimicrobial resistance of a multidrug resistant Klebsiella pneumoniae strain harboring bla NDM-1 were investigated to increase our understanding of the evolution of NDM-1. The strain, KPX, came from a Taiwanese patient with a hospitalization history in New Delhi. Complete DNA sequencing was performed; and the genes responsible for antimicrobial resistance were systematically examined and isolated by library screening. KPX harbored two resistance plasmids, pKPX-1 and pKPX-2, which are 250-kb and 141-kb in size, respectively, with bla NDM-1 present on pKPX-1. The plasmid pKPX-1 contained genes associated with the IncR and IncF groups, while pKPX-2 belonged to the IncF family. Each plasmid carried multiple antimicrobial resistance genetic determinants. The gene responsible for resistance to carbapenems was found on pKPX-1 and that for resistance to aztreonam was found on pKPX-2. To our surprise, we discovered that bla NDM-1 exists on pKPX-1 as multiple copies in the form of tandem repeats. Amplification of bla NDM-1 was found to occur by duplication of an 8.6-kb unit, with the copy number of the repeat varying from colony to colony. This repeat sequence is identical to that of the pNDM-MAR except for two base substitutions. The copy number of bla NDM-1 of colonies under different conditions was assessed by Southern blotting and quantitative PCR. The bla NDM-1 sequence was maintained in the presence of the antimicrobial selection; however, removal of antimicrobial selection led to the emergence of susceptible bacterial populations with a reduced copy number or even the complete loss of the bla NDM-1 sequence. The dynamic nature of the NDM-1 sequence provides a strong argument for judicious use of the broad-spectrum antimicrobials in order to reduce the development and spread of antimicrobial resistance among pathogens.

Sequence of closely related plasmids encoding bla(NDM-1) in two unrelated Klebsiella pneumoniae isolates in Singapore.

BACKGROUND: Spread of the bla(NDM-1) gene that encodes the New Delhi metallo-ß-lactamase (NDM-1) in Enterobacteriaceae is a major global health problem. Plasmids carrying bla(NDM-1) from two different multi-drug resistant Klebsiella pneumonia isolates collected in Singapore were completely sequenced and compared to known plasmids carrying bla(NDM-1). METHODOLOGY/PRINCIPAL FINDINGS: The two plasmids, pTR3 and pTR4, were transferred to Escherichia coli recipient strain J53 and completely sequenced by a shotgun approach using 3-kb paired-end libraries on 454. Although the K. pneumoniae strains were unrelated by molecular typing using PFGE and MLST, complete sequencing revealed that pTR3 and pTR4 are identical. The plasmid sequence is similar to the E. coli NDM-1-encoding plasmid p271A, which was isolated in Australia from a patient returning from Bangladesh. The immediate regions of the bla(NDM-1) gene in pTR3/4 are identical to that of p271A, but the backbone of our plasmid is much more similar to another IncN2 plasmid reported recently, pJIE137, which contained an additional 5.2-kb CUP (conserved upstream repeat) regulon region in comparison to p271A. A 257-bp element bounded by imperfect 39-bp inverted repeats (IR) and an incomplete version of this element flanking the 3.6-kb NDM-1-encoding region were identified in these plasmids and are likely to be the vestiges of an unknown IS. CONCLUSIONS: Although the hosts are not epidemiologically linked, we found that the plasmids bearing the bla(NDM-1) gene are identical. Comparative analyses of the conserved NDM-1-encoding region among different plasmids from K. pneumoniae and E. coli suggested that the transposable elements and the two unknown IR-associated elements flanking the NDM-1-encoding region might have aided the spreading of this worrisome resistance determinant.