Summary
Flowering relies on signaling networks that integrate endogenous and external cues. Normally, plants flower at a particular season, reflecting day length and/or temperature cues. However, ...plants can surpass this seasonal regulation and show precocious flowering under stress environmental conditions. Here, we show that UV‐C light stress activates the transition to flowering in Arabidopsis thaliana through salicylic acid (SA). Moreover, SA also regulates flowering time in non‐stressed plants, as SA‐deficient plants are late flowering. The regulation of flowering time by SA seems to involve the photoperiod and autonomous pathways, but it does not require the function of the flowering time genes CONSTANS (CO), FCA, or FLOWERING LOCUS C (FLC).
The present study was carried out to evaluate the prevalence of the clonal subgroup O16:H5-ST131 and the H30 and H30-Rx subclones among E. coli isolates causing extraintestinal infections and to know ...their virulence potential. The ST131 clonal group accounted for 490 (16%) of the 2995 isolates obtained from clinical samples in five Spanish hospitals during the study period (2005–2012). Among those 490 ST131 isolates, 456 belonged to serotype O25b:H4, 27 to O16:H5 and seven were O-non-typeable:H4 (ONT:H4). All 27 O16:H5 isolates showed fimH41, whereas fimH30 and fimH22 alleles were the most frequently detected among O25b:H4 isolates. The majority (381/490; 78%) of ST131 isolates belonged to H30 subclone, and 302 of 381 (79%) H30 isolates belonged to the H30-Rx subclone. Of the 27 O16:H5 isolates, 48% produced CTX-M-14; however, none produced CTX-M-15. In contrast, 46% of O25b:H4 isolates produced CTX-M-15 while only 2% produced CTX-M-14. More than a half of the O16:H5 isolates (56%) showed the ExPEC status which was significantly more prevalent within O25b:H4 isolates (81%) (P<0.01), especially among H30-Rx (97%) isolates. In the present study, a modified virotype scheme was applied within which approximately half (52%) of the O16:H5 isolates showed the C1 specific virotype. Despite their low virulence-gene score (mean of virulence genes 6.4 versus 8.5 in O25b:H4 isolates), six out of the 10 O16:H5 isolates assayed showed high virulence in the mouse model of sepsis (killed 90–100% of mice challenged). Furthermore, four O16:H5 isolates of virotypes A and C1, carrying K2 variant of group II capsule, showed lethality at 24h. Thus, certain O16:H5 fimH41 isolates show a similar in vivo virulence to that reported with the highly virulent O25b:H4 H30-Rx isolates (Mora et al., PLOS ONE 2014, e87025), supporting their potential virulence for humans.
A new CTX-M-type beta-lactamase (CTX-M-9) has been cloned from a clinical cefotaxime-resistant Escherichia coli strain. Despite the close identity that exists between the CTX-M-9 and Toho-2 ...beta-lactamases (88%), the 35 amino acids located between residues Ala-185 and Ala-219 are totally different in both enzymes. Outside of this region there are only six amino acids substitutions between both proteins.
Abstract The present study was carried out to evaluate the prevalence of the clonal subgroup O16:H5-ST131 and the H 30 and H 30-Rx subclones among E. coli isolates causing extraintestinal infections ...and to know their virulence potential. The ST131 clonal group accounted for 490 (16%) of the 2995 isolates obtained from clinical samples in five Spanish hospitals during the study period (2005–2012). Among those 490 ST131 isolates, 456 belonged to serotype O25b:H4, 27 to O16:H5 and seven were O-non-typeable:H4 (ONT:H4). All 27 O16:H5 isolates showed fimH 41, whereas fimH 30 and fimH 22 alleles were the most frequently detected among O25b:H4 isolates. The majority (381/490; 78%) of ST131 isolates belonged to H 30 subclone, and 302 of 381 (79%) H 30 isolates belonged to the H 30-Rx subclone. Of the 27 O16:H5 isolates, 48% produced CTX-M-14; however, none produced CTX-M-15. In contrast, 46% of O25b:H4 isolates produced CTX-M-15 while only 2% produced CTX-M-14. More than a half of the O16:H5 isolates (56%) showed the ExPEC status which was significantly more prevalent within O25b:H4 isolates (81%) ( P < 0.01), especially among H 30-Rx (97%) isolates. In the present study, a modified virotype scheme was applied within which approximately half (52%) of the O16:H5 isolates showed the C1 specific virotype. Despite their low virulence-gene score (mean of virulence genes 6.4 versus 8.5 in O25b:H4 isolates), six out of the 10 O16:H5 isolates assayed showed high virulence in the mouse model of sepsis (killed 90–100% of mice challenged). Furthermore, four O16:H5 isolates of virotypes A and C1, carrying K2 variant of group II capsule, showed lethality at 24 h. Thus, certain O16:H5 fimH 41 isolates show a similar in vivo virulence to that reported with the highly virulent O25b:H4 H 30-Rx isolates (Mora et al., PLOS ONE 2014, e87025), supporting their potential virulence for humans.
The aim of this study was to evaluate the incidence of decreased susceptibility to broad-spectrum cephalosporins in Enterobacteriaceae that lack inducible chromosomal bla genes, and to determine the ...enzymes responsible for resistance. From all clinically relevant Enterobacteriaceae strains isolated between 1994 and 1996, 88 of 7054 Escherichia coli, seven of 581 Klebsiella pneumoniae and 23 of 166 Klebsiella oxytoca strains were studied because of their decreased susceptibilities to broad-spectrum cephalosporins (as reflected in intermediate susceptibilities and/or positive synergy tests and/or irregular crenellated inhibition zones). The most frequent mechanism implicated in decreased susceptibility to broad-spectrum cephalosporins displayed by E. coli and K. oxytoca was hyperproduction of chromosomal β-lactamase, followed by plasmid-mediated SHV-1 hyperproduction in E. coli. In our hospital, the incidence of plasmid-mediated extended-spectrum β-lactamases (ESBLs) between 1994 and 1996 was low. ESBLs were found in only 10 (0.14%) E. coli strains (six CTX-M-9, two TEM-12 and two SHV-2), in one (0.17%) K. pneumoniae strain (SHV-2) and in no K. oxytoca strains. The relatively wide variety of β-lactamases that were detected among these common bacteria isolated from a single medical centre, including non-TEM- and non-SHV-derived ESBLs, appears epidemiologically remarkable.
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