Characteristics and Clinical Implications of Carbapenemase-Producing Klebsiella pneumoniae Colonization and Infection,Italy

Klebsiella pneumoniae carbapenemase–producing K. pneumoniae (KPC-Kp) has been endemic in Italy since 2013. In a multicenter cohort study, we investigated various aspects of KPC-Kp among patients, including 15-day mortality rates and delays in adequate therapy. Most (77%) KPC-Kp strains were sequence type (ST) ST512 or ST307. During 2017, KPC-Kp prevalence was 3.26 cases/1,000 hospitalized patients. Cumulative incidence of KPC-Kp acquired >48 hours after hospital admission was 0.68% but varied widely between centers. Among patients with mild infections and noninfected colonized patients, 15-day mortality rates were comparable, but rates were much higher among patients with severe infections. Delays of >4 days in receiving adequate therapy more frequently occurred among patients with mild infections than those with severe infections, and delays were less common for patients with known previous KPC-Kp colonization. Italy urgently needs a concerted surveillance system to control the spread of KPC-Kp.     

Use of meropenem in treating carbapenem-resistant Enterobacteriaceae infections

ABSTRACT

Introduction: The epidemiology of carbapenem-resistant Enterobacterales (CRE) is increasingly worldwide. Production of carbapenemases is the most common and efficient mechanism of carbapenem resistance, and could theoretically be overcome by optimizing the pharmacokinetic/pharmacodynamic (PK/PD) behavior of meropenem.

Areas covered: This article overviews the available literature concerning the potential role that meropenem may still have in the treatment carbapenem-resistant Enterobacteriaceae infections. Clinical studies published in English language until June 2019 were searched on PubMed database.

Expert commentary: High-dose continuous infusion meropenem-based combination regimens could still represent a valuable option for treating CRE infections in specific circumstances. Knowledge of the local prevalent mechanisms of carbapenem resistance, of patient clinical severity, of the site of infection, of an accurate minimum inhibitory concentration (MIC) value, coupled with the possibility of carrying-out a real-time therapeutic drug monitoring (TDM)-based PK/PD optimization of drug exposure must all be considered as fundamental for properly pursuing this goal.     

Mannose receptor modulates macrophage polarization and allergic inflammation through miR-511-3p

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Once daily high dose tigecycline - pharmacokinetic/pharmacodynamic based dosing for optimal clinical effectiveness: dosing matters,revisited

Introduction: Tigecycline has emerged as first line therapy for serious systemic infections due to important pathogens (except P. aeruginosa and Proteus sp.), including multi-drug resistant (MDR) and Gram negative bacilli (GNB), including carbapenem resistant Enterobacteriae. Tigecycline has a ‘low resistance potential,’ is protective against C. difficile, and is often the only antibiotic effective against MDR GNB, e.g., Klebsiella sp.

Areas covered: Standard dose tigecycline therapy has been used for intra-abdominal infections, complicated skin/skin structure infections (cSSSIs), and CAP. Clinical experience with once daily high dose tigecycline (HDT), i.e., 200 – 400 mg (IV) x 1, then 100 – 200 mg (IV) q24 h, is reviewed. Optimal tigecycline efficacy is dependent on PK/PD based dosing. Suboptimal outcomes have been due to inappropriate use or suboptimal dosing.

Expert commentary: Tigecycline’s spectrum against nearly all important pathogens (including MSSA/MRSA, VSE/VRE, B. fragilis, C. difficile, MDR and GNB) assures tigecycline a critical place in the antibiotic armamentarium. Dosed optimally, HDT can be a cornerstone of antibiotic stewardship programs in preventing C. difficile, treating MDR GNB pathogens, and in preventing resistance. Properly used and optimally dosed, once daily HDT should be considered preferred therapy for severe systemic infections and those due to MDR GNB pathogens.     

Improved Phenotype-Based Definition for Identifying Carbapenemase Producers among Carbapenem-Resistant Enterobacteriaceae

Preventing transmission of carbapenemase-producing, carbapenem-resistant Enterobacteriaceae (CP-CRE) is a public health priority. A phenotype-based definition that reliably identifies CP-CRE while minimizing misclassification of non–CP-CRE could help prevention efforts. To assess possible definitions, we evaluated enterobacterial isolates that had been tested and deemed nonsusceptible to >1 carbapenem at US Emerging Infections Program sites. We determined the number of non-CP isolates that met (false positives) and CP isolates that did not meet (false negatives) the Centers for Disease Control and Prevention CRE definition in use during our study: 30% (94/312) of CRE had carbapenemase genes, and 21% (14/67) of Klebsiella pneumoniae carbapenemase–producing Klebsiella isolates had been misclassified as non-CP. A new definition requiring resistance to 1 carbapenem rarely missed CP strains, but 55% of results were false positive; adding the modified Hodge test to the definition decreased false positives to 12%. This definition should be considered for use in carbapenemase-producing CRE surveillance and prevention.     

DCC is expressed in a CD166-positive subpopulation of chondrocytes in human osteoarthritic cartilage and modulates CRE activity

Objective: In a recent study we determined a strong differential expression of DCC in OA compared to normal chondrocytes and a strong impact of the DCC receptor on cellular mobility triggered by its ligand Netrin-1. Migration of chondrocytes or their progenitor cells may play a role in remodeling of cartilage and pathological conditions. The purpose of this study is to identify subsets of chondrocytes expressing DCC and to understand signaling pathways used by DCC in chondrocytes. Methods: Immunofluorescent histology of human cartilage was used to determine the expression pattern of CD166, DCC and p-CREB. Cell culture of chondrocytes and SW1353, transient transfection, siRNA transfection, EMSA, luciferase assay, quantitative RT-PCR, ELISA, and Western Blotting were used to study signaling down-stream of DCC. Results: DCC expressing chondrocytes are mainly located in the surface layers of OA cartilage. These also express CD166 indicating that DCC expressing chondrocytes are progenitor cells. Interestingly, expression of DCC reduces cAMP levels, CREB DNA-binding activity and CRE activity in chondrocytes, whereas down-regulation of DCC results in induction of CRE signaling. Conclusion: In summary, DCC is up-regulated in CD166-positive chondrogenic progenitor cells in OA and induces down-regulation of CREB. These findings indicate that migration of CD166 positive progenitor cells to sites of cartilage damage may be directed by regulation of DCC signaling.     

RNA aptamer‐mediated interference of HCV replication by targeting the CRE‐5BSL3.2 domain

Summary. The RNA genome of hepatitis C virus (HCV) contains multiple conserved structural RNA domains that play key roles in essential viral processes. A conserved structural component within the 3′ end of the region coding for viral RNA‐dependent RNA polymerase (NS5B) has been characterized as a functional cis‐acting replication element (CRE). This study reports the ability of two RNA aptamers, P‐58 and P‐78, to interfere with HCV replication by targeting the essential 5BSL3.2 domain within this CRE. Structure‐probing assays showed the binding of the aptamers to the CRE results in a structural reorganization of the apical portion of the 5BSL3.2 stem‐loop domain. This interfered with the binding of the NS5B protein to the CRE and induced a significant reduction in HCV replication (≈50%) in an autonomous subgenomic HCV replication system. These results highlight the potential of this CRE as a target for the development of anti‐HCV therapies and underscore the potential of antiviral agents based on RNA aptamer molecules.