Klebsiella pneumoniae strains producing KPC-type carbapenemases (KPC-KP) are challenging multidrug-resistant pathogens due to their extensively drug-resistant phenotypes and potential for epidemic ...dissemination in health care settings. Colistin is a key component of the combination antimicrobial regimens used for treatment of severe KPC-KP infections. We previously reported that insertional inactivation of the mgrB gene, encoding a negative-feedback regulator of the PhoQ-PhoP signaling system, can be responsible for colistin resistance in KPC-KP, due to the resulting upregulation of the Pmr lipopolysaccharide modification system. In this work we investigated the status of the mgrB gene in a collection of 66 colistin-resistant nonreplicate clinical strains of KPC-KP isolated from different hospitals in Italy and Greece. Overall, 35 strains (53%) exhibited alterations of the mgrB gene, including insertions of different types of mobile elements (IS5-like, IS1F-like, or ISKpn14), nonsilent point mutations, and small intragenic deletions. Four additional strains had a larger deletion of the mgrB locus, while the remaining 27 strains (41%) did not show mgrB alterations. Transcriptional upregulation of the phoQ and pmrK genes (part of the phoPQ and pmrHFIJKLM operon, respectively) was observed in all strains with mgrB alterations. Complementation experiments with a wild-type mgrB gene restored colistin susceptibility and basal expression levels of phoQ and pmrK genes in strains carrying different types of mgrB alterations. The present results suggest that mgrB alteration can be a common mechanism of colistin resistance among KPC-KP in the clinical setting.
E35048, a bloodstream isolate from Italy, was the first strain where the oxazolidinone resistance gene
was detected outside China. The strain was also positive for the oxazolidinone resistance gene
. ...WGS analysis revealed that the two genes were linked (23.1 kb apart), being co-carried by a 41,816-bp plasmid that was named pE35048-oc. This plasmid also carried the macrolide resistance gene
(B) and a backbone related to that of the well-known
plasmid pRE25 (identity 96%, coverage 65%). The
gene context was original,
being part of a composite transposon, named Tn
, which was integrated into the gene encoding for the ζ toxin protein (
of pRE25). The
gene was flanked by two IS
insertion sequences and the element was inserted into an
(E) gene. Both
and
contexts were excisable. pE35048-oc could not be transferred to enterococcal recipients by conjugation or transformation. A plasmid-cured derivative of
E35048 was obtained following growth at 42°C, and the complete loss of pE35048-oc was confirmed by WGS. pE35048-oc exhibited some similarity but also notable differences from pEF12-0805, a recently described enterococcal plasmid from human
also co-carrying
and
; conversely it was completely unrelated to other
- and
-carrying plasmids from
. The
-
linkage is a matter of concern since it could herald the possibility of a co-spread of the two genes, both involved in resistance to last resort agents such as the oxazolidinones.
is a major agent of healthcare-associated infections and a cause of some community-acquired infections, including severe bacteremic infections associated with metastatic abscesses in liver and other ...organs. Clinical relevance is compounded by its outstanding propensity to evolve antibiotic resistance. In particular, the emergence and dissemination of carbapenem resistance in
has posed a major challenge due to the few residual treatment options, which have only recently been expanded by some new agents. The epidemiological success of carbapenem-resistant
(CR-Kp) is mainly linked with clonal lineages that produce carbapenem-hydrolyzing enzymes (carbapenemases) encoded by plasmids.
Here, we provide an updated overview on the mechanisms underlying the emergence and dissemination of CR-Kp, focusing on the role that plasmids have played in this phenomenon and in the co-evolution of resistance and virulence in
.
CR-Kp have disseminated on a global scale, representing one of the most important contemporary public health issues. These strains are almost invariably associated with complex multi-drug resistance (MDR) phenotypes, which can also include recently approved antibiotics. The heterogeneity of the molecular bases responsible for these phenotypes poses significant hurdles for therapeutic and diagnostic purposes.
The pandemic dissemination of KPC carbapenemase-producing Klebsiella pneumoniae (KPC-KP) represents a major public health problem, given their extensive multidrug resistance profiles and primary role ...in causing healthcare-associated infections. This phenomenon has largely been contributed by strains of Clonal Group (CG) 258, mostly of clade II, which in some areas represent the majority of KPC-KP isolates. Here we have characterized a newly discovered lytic Podoviridae, named φBO1E, targeting KPC-KP strains of clade II lineage of CG258. Genomic sequencing revealed that φBO1E belongs to the Kp34virus genus (87% nucleotide identity to vB_KpnP_SU552A). ΦBO1E was stable over a broad pH and temperature range, exhibited strict specificity for K. pneumoniae strains of clade II of CG258, and was unable to establish lysogeny. In a Galleria mellonella infection model, φBO1E was able to protect larvae from death following infection with KPC-KP strains of clade II of CG258, including one colistin resistant strain characterized by a hypermucoviscous phenotype. To our best knowledge φBO1E is the first characterized lytic phage targeting K. pneumoniae strains of this pandemic clonal lineage. As such, it could be of potential interest to develop new agents for treatment of KPC-KP infections and for decolonization of subjects chronically colonized by these resistant superbugs.
Chronic headache is particularly prevalent in migraineurs and it can progress to a condition known as medication overuse headache (MOH). MOH is a secondary headache caused by overuse of analgesics or ...other medications such as triptans to abort acute migraine attacks. The worsening of headache symptoms associated with medication overuse (MO) generally ameliorates following interruption of regular medication use, although the primary headache symptoms remain unaffected. MO patients may also develop certain behaviors such as ritualized drug administration, psychological drug attachment, and withdrawal symptoms that have been suggested to correlate with drug addiction. Although several reviews have been performed on this topic, to the authors best knowledge none of them have examined this topic from the addiction point of view. Therefore, we aimed to identify features in MO and drug addiction that may correlate. We initiate the review by introducing the classes of analgesics and medications that can cause MOH and those with high risk to produce MO. We further compare differences between sensitization resulting from MO and from drug addiction, the neuronal pathways that may be involved, and the genetic susceptibility that may overlap between the two conditions. Finally, ICHD recommendations to treat MOH will be provided herein.
Background Fluid challenge may help in the differential diagnosis between pre- and postcapillary pulmonary hypertension (PH). However, the test is still in need of standardization and better defined ...clinical relevance. Methods Two hundred twelve patients referred for PH underwent a right-sided heart catheterization with measurements before and after rapid infusion of 7 mL/kg of saline. PH was defined as mean pulmonary artery pressure ≥ 25 mm Hg, and postcapillary PH was defined as pulmonary artery wedge pressure (PAWP) > 15 mm Hg. An increase in PAWP ≥ 18 mm Hg was considered diagnostic for postcapillary PH. At baseline, 66 patients received a diagnosis of no PH; 22, of postcapillary PH; and 124, of precapillary PH (mostly pulmonary arterial hypertension). Results After fluid challenge, five of 66 patients with no PH (8%) and eight of 124 with precapillary PH (6%) had the diagnosis reclassified as postcapillary PH. Fluid challenge was associated with an increase in PAWP by 7 ± 2 mm Hg in postcapillary PH and 3 ± 1 mm Hg in both precapillary PH and no-PH groups. Between-group differences were significant, but there was overlap. There were no adverse events related to fluid challenge. Prediction bands calculated from quadratic fits of the PAWP responses in pooled control subjects with no PH and patients with precapillary PH helped confirm 18 mm Hg as the cutoff for diagnosing postcapillary PH. Conclusions Fluid challenge with 7 mL/kg saline increases PAWP, more in postcapillary than in precapillary PH or in control subjects with no PH. A cutoff value of 18 mm Hg allows reclassification of 6% to 8% of patients with precapillary PH or normal hemodynamic characteristics at baseline.
Abstract
Objectives
To characterize the genetic element carrying the poxtA oxazolidinone resistance gene found in the poxtA index strain Staphylococcus aureus AOUC-0915 isolated from a cystic ...fibrosis patient.
Methods
The genetic context of poxtA was investigated by bioinformatics analysis of WGS data of strain AOUC-0915, followed by PCR and confirmatory Sanger sequencing for repetitive regions. Conjugation and electrotransformation experiments were carried out to assess horizontal transferability using S. aureus and Enterococcus faecalis recipients. Production of phage particles was evaluated by PCR using DNA preparations obtained after phage induction. Excision of the transposon carrying poxtA was evaluated by inverse PCR experiments for detection of circular intermediates.
Results
poxtA was found to be associated with a 48 kb composite transposon of original structure, named Tn6349, inserted into a φN315-like prophage. The transposon was bounded by two IS1216 insertion sequences, carried several resistance genes erm(B), cfr, poxtA and fexB and exhibited a mosaic structure made by a derivative of plasmid pE35048-oc (previously described in an Enterococcus faecium clinical isolate) and Tn6657, a novel composite transposon carrying the poxtA and fexB genes. Excision ability of Tn6349 as a circular intermediate was demonstrated. Transferability of Tn6349 or modules thereof to S. aureus or E. faecalis by either conjugation or electrotransformation was not detected. Induction of the φN315-like prophage carrying Tn6349 was not observed.
Conclusions
This study describes the structure of Tn6349, a novel composite transposon carrying several resistance determinants to anti-ribosomal drugs, including cfr and poxtA, from an oxazolidinone-resistant MRSA strain. Analysis of Tn6349 revealed a modular structure that could favour the mobilization of its resistance determinants.
Resistance to carbapenems in
, including
, represents a major clinical problem given the lack of effective alternative antibiotics. Bacteriophages could provide a valuable tool to control the ...dissemination of antibiotic resistant isolates, for the decolonization of colonized individuals and for treatment purposes. In this work, we have characterized a lytic bacteriophage, named vB_Kpn_F48, specific for
isolates belonging to clonal group 101. Phage vB_Kpn_F48 was classified as a member of
, order
, on the basis of transmission electron microscopy analysis. Physiological characterization demonstrated that vB_Kpn_F48 showed a narrow host range, a short latent period, a low burst size and it is highly stable to both temperature and pH variations. High throughput sequencing and bioinformatics analysis revealed that the phage is characterized by a 171 Kb dsDNA genome that lacks genes undesirable for a therapeutic perspective such integrases, antibiotic resistance genes and toxin encoding genes. Phylogenetic analysis suggests that vB_Kpn_F48 is a T4-like bacteriophage which belongs to a novel genus within the
subfamily, which we tentatively named "
". Considering the narrow host range, the genomic features and overall physiological parameters phage vB_Kpn_F48 could be a promising candidate to be used alone or in cocktails for phage therapy applications.
Background and Aims
Hepatocellular carcinoma (HCC) recurrence is common in patients treated with liver resection (LR). In this study, we aimed to evaluate the incidence and preoperative predictors of ...non‐transplantable recurrence in patients with single HCC ≤5 cm treated with frontline LR.
Methods
From the Italian Liver Cancer (ITA.LI.CA) database, 512 patients receiving frontline LR for single HCC ≤5 cm were retrieved. Incidence and predictors of recurrence beyond Milan criteria (MC) and up‐to‐seven criteria were compared between patients with HCC <4 and ≥4 cm.
Results
During a median follow‐up of 4.2 years, the overall recurrence rate was 55.9%. In the ≥4 cm group, a significantly higher proportion of patients recurred beyond MC at first recurrence (28.9% vs. 14.1%; p < 0.001) and overall (44.4% vs. 25.2%; p < 0.001). Similar results were found considering recurrence beyond up‐to‐seven criteria. Compared to those with larger tumours, patients with HCC <4 cm had a longer recurrence‐free survival and overall survival. HCC size ≥4 cm and high alpha‐fetoprotein (AFP) level at the time of LR were independent predictors of recurrence beyond MC (and up‐to‐seven criteria). In the subgroup of patients with available histologic information (n = 354), microvascular invasion and microsatellite lesions were identified as additional independent risk factors for non‐transplantable recurrence.
Conclusions
Despite the high recurrence rate, LR for single HCC ≤5 cm offers excellent long‐term survival. Non‐transplantable recurrence is predicted by HCC size and AFP levels, among pre‐operatively available variables. High‐risk patients could be considered for frontline LT or listed for transplantation even before recurrence.
Diabetic foot is a significant cause of morbidity in diabetic patients, with a rate that is approximately twice that of patients without foot ulcers. "Metabolic memory" represents the epigenetic ...changes induced by chronic hyperglycaemia, despite the correction of the glucose levels themselves. These epigenetic modifications appear to perpetuate the damage caused by persistently elevated glucose levels even in their absence, acting at various levels, mostly affecting the molecular processes of diabetic ulcer healing.
The aim of our cross-sectional study was to analyse a cohort of patients with diabetes with and without lower limb ulcers. We examined the effects of epigenetic changes on miRNA 126, 305, and 217 expression and the frequency of the SNPs of genes encoding inflammatory molecules (e.g., IL-6 and TNF-alpha) and their correlations with serum levels of proangiogenic molecules (e.g., ENOS, VEGF and HIF-1alpha) and several adipokines as well as with endothelial dysfunction, assessed noninvasively by reactive hyperaemia peripheral artery tonometry. Between March 2021 and June 2022, 110 patients were enrolled into the study: 50 diabetic patients with diabetic foot injuries, 40 diabetic patients without ulcerative complications and 20 nondiabetic patients as the control group.
Diabetic subjects with lower limb ulcerative lesions exhibited higher levels of inflammatory cytokines, such as VEGF (191.40 ± 200 pg/mL vs. 98.27 ± 56.92 pg/mL vs. 71.01 ± 52.96 pg/mL; p = 0.22), HIF-1alpha (40.18 ± 10.80 ng/mL vs. 33.50 ± 6.16 ng/mL vs. 33.85 ± 6.84 ng/mL; p = 0.10), and Gremlin-1 (1.72 ± 0.512 ng/mL vs. 1.31 ± 0.21 ng/mL vs. 1.11 ± 0.19 ng/mL; p < 0.0005), than those without lower limb ulcers and healthy controls. Furthermore, we observed that miR-217-5p and miR-503-5p were 2.19-fold (p < 0.05) and 6.21-fold (p = 0.001) more highly expressed in diabetic foot patients than in healthy controls, respectively. Additionally, diabetic patients without lower limb ulcerative complications showed 2.41-fold (p = 0) and 2.24-fold (p = 0.029) higher expression of miR-217-5p and miR-503-5p, respectively, than healthy controls. Finally, diabetic patients with and without ulcerative complications of the lower limbs showed higher expression of the VEGFC2578A CC polymorphism (p = 0.001) and lower expression of the VEGFC2578A AC polymorphism (p < 0.005) than the healthy control population. We observed a significant increase in Gremlin-1 levels in patients with diabetic foot, suggesting that this inflammatory adipokine may serve as a predictive marker for the diagnosis of diabetic foot.
Our results highlighted that patients with diabetic foot showed predominant expression of the VEGF C2578A CC polymorphism and reduced expression of the AC allele. Additionally, we found an overexpression of miR-217-5p and miR-503-5p in diabetic patients with and without diabetic foot syndrome compared with healthy controls. These results align with those reported in the literature, in which the overexpression of miR-217-5p and miR-503-5p in the context of diabetic foot is reported. The identification of these epigenetic modifications could therefore be helpful in the early diagnosis of diabetic foot and the treatment of risk factors. However, further studies are necessary to confirm this hypothesis.
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