Characterization of coagulase-negative staphylococcal isolates from blood with reduced susceptibility to glycopeptides and therapeutic options

<p>Abstract</p> <p>Background</p> <p>Coagulase-negative staphylococci (CoNS) are a major cause of nosocomial blood stream infection, especially in critically ill and haematology patients. CoNS are usually multidrug-resistant and glycopeptide antibiotics have been to date considered the drugs of choice for treatment. The aim of this study was to characterize CoNS with reduced susceptibility to glycopeptides causing blood stream infection (BSI) in critically ill and haematology patients at the University Hospital Tor Vergata, Rome, Italy, in 2007.</p> <p>Methods</p> <p>Hospital microbiology records for transplant haematology and ICU were reviewed to identify CoNS with elevated MICs for glycopeptides, and isolates were matched to clinical records to determine whether the isolates caused a BSI. The isolates were tested for susceptibility to new drugs daptomicin and tigecycline and the genetic relationship was assessed using f-AFLP.</p> <p>Results</p> <p>Of a total of 17,418 blood cultures, 1,609 were positive for CoNS and of these, 87 (5.4%) displayed reduced susceptibility to glycopeptides. Clinical review revealed that in 13 cases (7 in haematology and 6 in ICU), CoNS with reduced susceptibility to glycopeptides were responsible for a BSI. <it>Staphylococcus epidermidis </it>was the causative organism in 11 instances and <it>Staphylococcus haemolyticus </it>in 2. The incidence of oxacillin resistance was high (77%), although all isolates remained susceptible to linezolid, daptomycin and tigecycline. Fingerprinting of CoNS identified one clonal relationship between two isolates.</p> <p>Conclusion</p> <p>Multi-resistant CoNS with reduced susceptibility to glycopeptides, although still relatively infrequent in our hospital, are emerging pathogens of clinical concern. Surveillance by antibiotyping with attention to multi-resistant profile, and warning to clinicians, is necessary.</p

Fragility curves for free and restrained rocking masonry façades in one-sided motion

This paper deals with the need of extending results of deterministic rocking analyses to stochastic analyses on restrained masonry façades in one-sided motion. The purpose is to define the level of improvement achieved with any anti-seismic device of a given stiffness and strength, in terms of reduction of probability of exceedance of a certain limit state. The most efficient intensity measures (IMs) are identified for three masonry façades of churches in free and restrained conditions. A reliability analysis is carried out by considering over 70 earthquakes, of which 50 recorded during the recent 2016–2017 Central Italy Earthquake. Four limit states are taken into account: rocking initiation, limited rocking, moderate rocking and near-collapse condition. The yielding limit state is considered for the analysis with anti-seismic devices. Univariate and bivariate fragility curves (FCs) are compared in free and restrained configurations, to discuss the reduction of probability of exceedance depending on 15 intensity measures. The results show that the best IMs are velocity-based parameters, in particular the Fajfar Index and Peak Ground Velocity, together with Peak Ground Acceleration. In one-sided motion without restraints, the higher the compression stiffness of the sidewalls, the more unstable the wall is in probabilistic terms. Practical curves show, for each IM, the reduction of probability of exceedance obtained thanks to assumed horizontal restraints. These help to understand, in a stochastic perspective, to what extent the anti-seismic device can be beneficial or detrimental (in case of amplifications of motion) for given earthquake intensities. The comparison of univariate and bivariate FCs confirms the superiority of bivariate FCs. Indeed, often the univariate curves sensitively underestimate the probability of exceedance, especially for low-medium intensity earthquakes, and are not able to offer any information regarding the influence of other IMsThe authors thank the sponsorship of the Italian Department of Civil Protection, in the framework of the RELUIS Project - Masonry Structures (2018) and Eng. Fabio Solarino for helping in the calculations.info:eu-repo/semantics/publishedVersio

Archaeological consolidation of UNESCO masonry structures in Oman: the Sumhuram Citadel of Khor Rori and the Al Balid Fortress

A series of missions, starting from early 2005 up to 2009, have been managed to restore the ancient city walls of Sumhuram (4th B.C. – 6th A.D.) in the site of Khor Rori, together with a group of archaeologists of the University of Pisa. Also, from early 2007 a series of missions have been managed to consolidate the dry masonry Fortress in UNESCO site of Al Balid erected about 1100 A.D. with archaeologists of the University of Missouri. Both sites are located in the area of Salalah in southern part of the Sultanate of Oman. The sequence of dry season and rainy season during the Khareef period (Monsoon phenomena) caused several collapses on the excavated masonry structures, with risks for safety of visitors and archaeologists. The walls of Sumhuram, affected by the loss of connection between the two limestone masonry faces, have been rebuilt with the original texture of bricks using a new mix design for mortar joints with the same colors, consistency and proper strength and durability. The safety level of the consolidation works is evaluated by observing on site the shape of the collapse surfaces and using the classical limit analysis approach. The collapses of Al Balid dry masonry walls have been originated by the loss of permeability of the external wall faces due to the progressive filling of joint by soil; consolidation activities consisted to rebuild with the same blocks down and to substitute the earth behind the external layers with gravel and high permeability filling. An analytical model of dry rigid block masonry with frictional interfaces has been used to represent the out-of-plane behaviour, in order to define the maximum height of excavation and the maximum free height of the restored walls to guarantee safety for workers