Plasmids as donors of Insertion Sequence elements mediating colistin resistance in Klebsiella pneumoniae

Colistin is a last resort antibiotic for the treatment of carbapenemase producing Klebsiella pneumoniae (CRKP) and other extensively drug resistant (XDR) gram-negative bacterial isolates. In line with rising colistin use worldwide, colistin resistant Klebsiella pneumoniae (K. pneumoniae) isolates have emerged. Insertion sequences (IS) integrating into the mgrB gene represents a significant mechanism mediating the emergence of colistin resistance in clinical settings. The disruption of mgrB by ISs has been widely reported worldwide. Evidence suggests plasmids encode mobilizable IS elements which preferentially integrate into the mgrB gene in K. pneumoniae causing gene inactivation and colistin resistance. Recognised IS elements targeting mgrB include ISL3 (ISKpn25), IS5 (ISKpn26), ISKpn14 and IS903B-like elements. K. pneumoniae represents the single largest species carrying plasmids encoding each IS element. The nucleotide reference sequence for ISKpn25, ISKpn26, ISKpn14 and IS903B were downloaded from IS finder. The BLATSn tool from NCBI was used to retrieve sequences producing significant alignment. For IS presence among species, 1000 BLASTn hits were downloaded and filtered for plasmids. Additionally, the top 120 BLASTn non-duplicate circularised plasmid contig hits for each IS element were typed for incompatibility (Inc) group and carbapenemase gene presence. Metadata pertaining to each sample was retrieved, including isolate source information to aid the understanding of the clinical threat posed by IS elements. IS903B was found in 28 unique Inc groups, while ISKpn25 was largely carried by IncFIB(pQil) plasmids. ISKpn26 and ISKpn14 were most often found associated with IncFII(pHN7A8) plasmids. Of the 34 unique countries which contained any of the IS elements, ISKpn25 was identified from 26. India, USA, and Italy were the isolation origin country for 16.6%, 13.3%, and 9.2%, respectively of the ISKpn25 insertions identified in plasmids. In contrast, ISKpn26, ISKpn14, and IS903B insertion sequences were identified from 89.3%, 44.9% and 23.9% plasmid samples from China. The stratification of carbapenemase genes presence and isolation source between ISKpn25, ISKpn26, ISKpn14 and IS903B bearing plasmids was markedly different. A significant difference between IS elements and the distribution of carbapenemase genes (χ2(3, N = 480) = 155.12, p = <.001) was detected. In addition, a significant difference between IS elements and source isolation distribution (χ2(3, N = 382) = 46.97, p = <.001) was also observed. Post hoc analysis revealed IS903B has a significantly different (p = <.001) carbapenemase and source isolation distribution relative to ISKpn26, ISKpn14 or ISKpn25. The odds ratio revealed plasmids carrying ISKpn25, ISKpn14, and ISKpn26 IS elements are 12.18, 27.0, and 44.43 times more likely to carry carbapenemase genes relative to plasmids carrying the IS element IS903B. Moreover, the odds ratio reveled ISKpn26, ISKpn25, and ISKpn14 were 6.10, 28.82, and 31.47 times more likely to be sourced from a clinical environmental setting than the environment relative to IS903B IS harboring plasmids. ISKpn25 present on IncFIB(pQil) sourced from clinical settings is established across multiple countries, while ISKpn26, ISKpn14, and IS903B appear most often in China. High carbapenemase presence in tandem with IS elements may help promote an extensively drug resistant profile in K. pneumoniae. IS element mobilisation into the mgrB gene has been linked to colistin treatment therapy, while carbapenemase gene presence has been associated with the epidemic success of K. pneumoniae in clinical settings. Plasmids which harbour both carbapenemases and IS elements may engender an extensively drug resistant phenotype during colistin therapy in hospitals.

Bacterial adaptation by a transposition burst of an invading IS element

The impact of transposable elements on host fitness range from highly deleterious to beneficial, but their general importance for adaptive evolution remains debated. Here, we investigated whether IS elements are a major source of beneficial mutations during 400 generations of laboratory evolution of the cyanobacterium Acaryochloris marina strain CCMEE 5410, which has experienced a recent or on-going IS element expansion. The dynamics of adaptive evolution were highly repeatable among eight independent experimental populations and included beneficial mutations related to exopolysaccharide production and inorganic carbon concentrating mechanisms for photosynthetic carbon fixation. Most detected mutations were IS transposition events, but, surprisingly, the majority of these involved the copy-and-paste activity of only a single copy of an unclassified element (ISAm1) that has recently invaded the genome of A. marina strain CCMEE 5410. Our study reveals that the activity of a single transposase can fuel adaptation for at least several hundred generations.Impact statementA single transposable element can fuel adaptation to a novel environment for hundreds of generations without an apparent accumulation of a deleterious mutational load.

Complete Genome Sequencing of Four Arcobacter Species Reveals a Diverse Suite of Mobile Elements

Arcobacter species are recovered from a wide variety of sources, including animals, food, and both fresh and marine waters. Several Arcobacter species have also been recovered from human clinical samples and are thus associated tentatively with food- and water-borne human illnesses. Genome sequencing of the poultry isolate Arcobacter cibarius H743 and the Arcobacter acticola, Arcobacter pacificus, and Arcobacter porcinus type strains identified a large number and variety of insertion sequences. This study presents an analysis of these A. acticola, A. cibarius, A. pacificus, and A. porcinus IS elements. The four genomes sequenced here contain 276 complete and degenerate IS elements, representing 13 of the current 29 prokaryotic IS element families. Expansion of the analysis to include 15 other previously sequenced Arcobacter spp. added 73 complete and degenerate IS elements. Several of these IS elements were identified in two or more Arcobacter species, suggesting movement by horizontal gene transfer between the arcobacters. These IS elements are putatively associated with intragenomic deletions and inversions, and tentative movement of antimicrobial resistance genes. The A. cibarius strain H743 megaplasmid contains multiple IS elements common to the chromosome and, unusually, a complete ribosomal RNA locus, indicating that larger scale genomic rearrangements, potentially resulting from IS element-mediated megaplasmid cointegration and resolution may be occurring within A. cibarius and possibly other arcobacters. The presence of such a large and varied suite of mobile elements could have profound effects on Arcobacter biology and evolution.

Synthetic Elements

The periodic table consists of about 90 elements that occur naturally ending with element 92 uranium. This lack of precision is deliberate since one or two elements such as technetium were first created artificially and only later found to occur naturally on earth. This kind of occurrence provides a foreshadowing of things to come when we begin to discuss the transuranium elements, meaning those beyond uranium that have been artificially synthesized. Chemists and physicists have succeeded in synthesizing some of the elements that were missing between hydrogen (1) and uranium (92). In addition, they have synthesized a further 25, or so, new elements beyond uranium, although, again, one or two of these elements, like neptunium and plutonium, were later found to exist naturally in exceedingly small amounts. The existence of superheavy elements raises a number of interesting questions that pertain to the field of philosophy of science and also sociology of science. In fact, the very question of whether these superheavy elements actually exist needs to be dissected further, as it will be in the course of this chapter. The synthetic elements are extremely unstable, and only the lightest ones among them have been created in amounts large enough to be observed. Roughly speaking, the heavier the atom, the shorter its lifetime is. For example, the heaviest element for which there is now conclusive evidence is element 118, a few atoms of which have been created in just one single isotope form and with a half-life of less than a millisecond. Laypersons and specialists alike have asked themselves in what sense these elements can really be said to exist. The superheavy elements also have philosophical implications for the study of the periodic system as a whole and the question of whether there is a natural end to chemical periodicity. A related question, which has now become quite pressing, is the possible extension of the periodic table to include a new g-block which in formal terms should begin at element 121.

Higher prevalence of multi-antimicrobial resistant Bacteroides spp. strains isolated at a tertiary teaching hospital, China

Background: The antimicrobial resistance of Bacteroides spp. isolates is reported to be increasing among different districts around the world, and few reports found that multi-antimicrobial resistant strains emerged. However, less is known about the prevalence of multi-antimicrobial resistant isolates in China, especially for carbapenem resistance. Methods: Bacteroides spp. clinical strains were isolated from inpatients at a 3000 bed tertiary teaching hospital , and were identified by MALDI-TOF MS and VITEK-2 anaerobes and corynebacterium (ANC) card. Broth microdilution method was employed to detect the antimicrobial sensitivities of Bacteroides spp. isolates and PCR method was used to detect the resistance genes, including cfxA, cepA, cfiA, ermF and nim. The upstream insertion sequence (IS) element of cfiA gene was further detected and verified. Results: Among 115 Bacteroides spp. strains enrolled in this study, 80 isolates were Bacteroides fragilis and 35 isolates were non-Bacteroides fragilis. The total resistance rates of 115 Bacteroides spp. isolates to ampicillin/sulbactam, amoxicillin/clavulanic, cefoxitin, piperacillin, piperacillin/tazobactam, moxifloxacin, clindamycin, metronidazole, imipenem and meropenem were 22.6%, 19.6%, 3.5%, 27.8%, 8.7%, 16.5%, 80.0%, 5.2%, 13.9% and 13.9% , respectively. Except cefoxitin and moxifloxacin, the resistance rates of B. fragilis isolates to the above antibiotics were all higher than those of non-B. fragilis isolates. The positive rates of carbapenem resistance gene cfiA were 38.9% and 8.6% for B. fragilis and non-B. fragilis isolates, respectively. For 15 carbapenem resistant B. fragilis isolates, the co-carrying rates of carbapenem resistance gene cfiA and its upstream IS element were 86.7% (13/15). Conclusions: The overall resistance rates of Bacteroides spp. isolates toward multiple antibiotics were at a higher level, especially for B. fragilis. CfiA gene carrying rate among B. fragilis isolates was high up to 38.9% and its mediated carbapenem resistance was a major resistance mechanism for B. fragilis. The findings of this study imply that the actual resistance tendency of Bacteroides spp. may be underestimated and need to be given more attention to.

Transposition of Insertion Sequences was Triggered by Oxidative Stress in Radiation-Resistant Bacterium Deinococcus geothermalis

During an oxidative stress-response assay on a putative Dps-like gene-disrupted Δdgeo_0257 mutant strain of radiation-resistant bacterium Deinococcus geothermalis, a non-pigmented colony was observed among the normal reddish color colonies. This non-pigmented mutant cell subsequently displayed higher sensitivity to H2O2. While carotenoid has a role in protecting as scavenger of reactive oxygen species the reddish wild-type strain from radiation and oxidative stresses, it is hypothesized that the carotenoid biosynthesis pathway has been disrupted in the mutant D. geothermalis cell. Here, we show that, in the non-pigmented mutant cell of interest, phytoene desaturase (Dgeo_0524, crtI), a key enzyme in carotenoid biosynthesis, was interrupted by transposition of an ISDge7 family member insertion sequence (IS) element. RNA-Seq analysis between wild-type and Δdgeo_0257 mutant strains revealed that the expression level of ISDge5 family transposases, but not ISDge7 family members, were substantially up-regulated in the Δdgeo_0257 mutant strain. We revealed that the non-pigmented strain resulted from the genomic integration of ISDge7 family member IS elements, which were also highly up-regulated, particularly following oxidative stress. The transposition path for both transposases is a replicative mode. When exposed to oxidative stress in the absence of the putative DNA binding protein Dgeo_0257, a reddish D. geothermalis strain became non-pigmented. This transformation was facilitated by transposition of an ISDge7 family IS element into a gene encoding a key enzyme of carotenoid biosynthesis. Further, we present evidence of additional active transposition by the ISDge5 family IS elements, a gene that was up-regulated during the stationary phase regardless of the presence of oxidative stress.

Daya Dukung Iklim Organisasi Sekolah Terhadap Motivasi Guru

Base on empirical condition that motivation capacity is not stagnant but fluctuative for every body as member of organization, in meaning sometime strong position or opposite is weak, that are depend on strong or weakness the stimulus factor received by human resousrces. That will to be problem when the motivation being weak position. Thus will effect bad for organization life in future. In the school organization context, the climate is element part of external motivation of human resources any body include the teacher.Rembering that school organization climateis is given effect to the teacher motivation in work, so we can state that school organization climate have empirical support to the teachers motivation in spite of research case have done that the support is litle bite.ABSTRAKBertitik tolak dari kondisi empirik bahwa kadar motivasi yang ada dan dialami oleh setiap individu anggota organisasi tidaklah bersifat stagnan, melainkan bersifat fluktuatif, dalam artian terkadang berada pada posisi kuat atau sebaliknya berada pada posisi lemah, hal tersebut sangat bergantung kepada kuat lemahnya factor stimulus yang diterima sumber daya manusia. Yang menjadi persoalan adalah manakala motivasi itu berada pada posisi lemah. Keadaan demikian akan berdampak tidak baik bagi kehidupan organisasi di masa-masa mendatang. Dalam konteks organisasi sekolah, iklim merupakan bagian dari unsur stimulus eksternal motivasi sumber daya manusia, siapapun termasuk di dalamnya adalah para pendidik. Mengingat bahwa iklim organisasi sekolah memberikan berpengaruh terhadap motivasi guru dalam bekerja, maka dapat dinyatakan bahwa iklim organisasi sekolah memiliki daya dukung yang nyata terhadap motivasi guru meskipun dalam kasus penelitian yang dilakukan dukungannya kecil.