Formation Flying SAR: Analysis of Imaging Performance by Array Theory

This article analyzes the process of image synthesis for a formation flying synthetic aperture radar (FF-SAR), which is a multistatic synthetic aperture radar (SAR) based on a cluster of receiving-only satellites flying in a close formation, in the framework of the array theory. Indeed, the imaging properties of different close receivers, when analyzed as isolated items, are very similar and form the so-called common array. Moreover, the relative positions among the receivers implicitly define a physical array, referred to as spatial diversity array. FF-SAR imaging can be verified as a result of the spatial diversity array weighting the common array. Hence, different approaches to beamforming can be applied to the spatial diversity array to provide the FF-SAR with distinctive capabilities, such as coherent resolution enhancement and high-resolution wide-swath imaging. Simulation examples are discussed which confirm that array theory is a powerful tool to quickly and easily characterize FF-SAR imaging performance

High Performance Liquid Chromatography Tandem Mass Spectrometry Measurement of Bimatoprost, Latanoprost and Travoprost in Eyelash Enhancing Cosmetic Serums

Most common prostaglandin analogs, bimatoprost, latanoprost and travoprost, are licensed for the reduction of elevated intraocular pressure in patients with open angle glaucoma and ocular hypertension, but their non approved use as eyelash enhancers is becoming popular, especially in patients with eyelashes hypotrichosis. A fast and sensitive high performance liquid chromatography tandem mass spectrometry method was developed for the measurement of bimatoprost, latanoprost and travoprost in cosmetic serums freely web-sold to increase eyelash length, thickness and darkness. The analytes and the internal standard (reserpine) were separated by reversed phase chromatography with 5 mM ammonium acetate with 0.02% formic acid (mobile phase A) and 5 mM ammonium acetate in acetonitrile/water (95/5; v/v) with 0.02% formic acid (mobile phase B) by gradient elution and detected with tandem mass spectrometry operated in multiple reaction monitoring mode. Linearity between 1 and 500 μg/g shows good correlation coefficients (r2 = 0.99) for all substances. Analytical recovery of analytes under investigation were always higher than 90% and intra-assay and inter-assay precision and accuracy always better than 11%. This method was successfully applied to analyze cosmetic serums freely sold on the Internet websites

tst1-positive ST22-MRSA-IVa in healthy Italian preschool children

A survey was performed in May 2013 to assess methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization in healthy children attending 26 municipal daycare centres in Palermo, Italy. Of the 500 children, ten (2 %) tested positive. Eight MRSA isolates were tst1-positive ST22-MRSA-IVa, spa t223; the other two isolates were identified as ST1-IVa and ST398-V, respectively. tst1-positive ST22-MRSA, spa t223 has been previously identified only in the Middle Eastern area

Healthcare associated pathogens in a changing world

In developed countries about 10% of the hospitalizations are complicated by a healthcare-associated infection [1]. Up to 75% of these infections are due to multidrug-resistant organisms (MDROs) [1]. Antimicrobial resistant bacterial infections are associated to higher morbidity, mortality and healthcare costs than those caused by susceptible organisms [1]. The findings of the point prevalence survey in European acute care hospitals published in 2013 by the European Centre for Disease Control and Prevention (ECDC) show large variations between countries and between different regions of the same country, with Italy being allocated within the high-endemic areas for both MRSA and MDROs [2]. Despite antimicrobial resistance affects most bacterial species, MDR Gram negatives represent the most serious threat. In a few years Enterobacteriaceae, mainly Escherichia coli and Klebsiella pneumoniae, have evolved from extended spectrum β-lactamase (ESBL) producing to carbapanem-resistant organisms [3]. Simultaneously, Acinetobacter baumannii has quickly become extremely or pan-drug resistant [4]. Carbapenem resistant Gram negatives heavily impact on clinical outcomes with mortality rates significantly higher than the susceptible strains of the same species [1]. Of further concern, very few antimicrobial agents are available for an effective treatment of these infections and new agents active against these organisms are not currently in development. Many intertwining factors are driving these epidemiological changes, involving patients, healthcare delivery systems, infection control practices and, most important, misuse and inappropriate use of antibiotics in all healthcare facilities, in community and in animal husbandry. In particular, the transition of the healthcare delivery systems from a hospital-centered model to a healthcare facility network has gradually blurred the borders between hospital and community and the patients’ travel within this network has critically contributed to disseminate MDROs [5]. As a consequence, antimicrobial resistance is now as common, if not more so, in post-acute clinical facilities, such as long term care settings and nursing homes [5]. The “revolving door” is the very efficacious image used as the paradygm of the spreading routes of organisms with hospital and community reservoirs, as E. coli or MRSA. The revolving door, indeed, enlightens how the colonized patients entering back and forth several healthcare settings drive the amplification of the antibiotic resistance [6]. Stringent infection control and prevention practices and wise use of antibiotics are unanimously agreed as the key actions to fight MDROs. Of course, we need new antibiotics, but first we have to learn how to protect them from a precipitous erosion of their effectiveness

Characterization of Bacillus cereus Group Isolates From Human Bacteremia by Whole-Genome Sequencing

Members of the Bacillus cereus group are spore-forming organisms commonly associated with food poisoning and intestinal infections. Moreover, some strains of the group (i.e., B. cereus sensu stricto and Bacillus thuringiensis) can cause bacteremia in humans, mainly in immunocompromised individuals. Here we performed the genetic characterization of 17 human clinical strains belonging to B. cereus group isolated from blood culture. The whole-genome sequencing (WGS) revealed that the isolates were closely related to B. cereus sensu stricto and B. thuringiensis–type strain. Multilocus sequence typing analysis performed on the draft genome revealed the genetic diversity of our isolates, which were assigned to different sequence types. Based on panC nucleotide sequence, the isolates were grouped in the phylogenetic groups III and IV. The NHE, cer, and inhA gene cluster, entA, entFM, plcA, and plcB, were the most commonly detected virulence genes. Although we did not assess the ability to generate biofilm by phenotypic tests, we verified the prevalence of biofilm associated genes using an in silico approach. A high prevalence of pur gene cluster, xerC, clpY, codY, tasA, sipW, sinI, and sigB genes, was found. Genes related to the resistance to penicillin, trimethoprim, and ceftriaxone were identified in most of the isolates. Intriguingly, the majority of these virulence and AMR genes appeared to be evenly distributed among B. cereus s.s. isolates, as well as closely related to B. thuringiensis isolates. We showed the WGS represents a good approach to rapidly characterize B. cereus group strains, being able to give useful information about genetic epidemiology, the presence of virulence and antimicrobial genes, and finally about the potential hazard related to this underestimated risk

The Increasing Challenge of Multidrug-Resistant Gram-Negative Bacilli: Results of a 5-Year Active Surveillance Program in a Neonatal Intensive Care Unit

Colonization and infection by multidrug-resistant gram-negative bacilli (MDR GNB) in neonatal intensive care units (NICUs) are increasingly reported.We conducted a 5-year prospective cohort surveillance study in a tertiary NICU of the hospital "Paolo Giaccone," Palermo, Italy. Our objectives were to describe incidence and trends of MDR GNB colonization and the characteristics of the most prevalent organisms and to identify the risk factors for colonization. Demographic, clinical, and microbiological data were prospectively collected. Active surveillance cultures (ASCs) were obtained weekly. Clusters of colonization by extended spectrum β-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae were analyzed by conventional and molecular epidemiological tools.During the study period, 1152 infants were enrolled in the study. Prevalences of colonization by MDR GNB, ESBL-producing GNB and multiple species/genera averaged, respectively, 28.8%, 11.7%, and 3.7%. Prevalence and incidence density of colonization by MDR GNB and ESBL-producing GNB showed an upward trend through the surveillance period. Rates of ESBL-producing E coli and K pneumoniae colonization showed wide fluctuations peaking over the last 2 years. The only independent variables associated with colonization by MDR GNB and ESBL-producing organisms and multiple colonization were, respectively, the days of NICU stay (odds ratio [OR] 1.041), the days of exposure to ampicillin-sulbactam (OR 1.040), and the days of formula feeding (OR 1.031). Most clusters of E coli and K pneumoniae colonization were associated with different lineages. Ten out of 12 clusters had an outborn infant as their index case.Our study confirms that MDR GNB are an increasing challenge to NICUs. The universal once-a-week approach allowed us to understand the epidemiology of MDR GNB, to timely detect new clones and institute contact precautions, and to assess risk factors. Collection of these data can be an important tool to optimize antimicrobials use and control the emergence and dissemination of resistances in NICU

The burden of Candida species colonization in NICU patients: a colonization surveillance study

Fungal infections are an important cause of morbidity and mortality in neonatal intensive care units (NICUs). The identification of specific risk factors supports prevention of candidemia in neonates. Effective prophylactic strategies have recently become available, but the identification and adequate management of high-risk infants is still a priority. Prior colonization is a key risk factor for candidemia. For this reason, surveillance studies to monitor incidence, species distribution, and antifungal susceptibility profiles, are mandatory. Among 520 infants admitted to our NICU between January 2013 and December 2014, 472 (90.77%) were included in the study. Forty-eight out of 472 (10.17%) patients tested positive for Candida spp. (C.), at least on one occasion. All the colonized patients tested positive for the rectal swab, whereas 7 patients also tested positive for the nasal swab. Fifteen out of 472 patients (3.18%) had more than one positive rectal or nasal swab during their NICU stay. Moreover, 9 out of 15 patients tested negative at the first sampling, suggesting they acquired Candida spp. during their stay. Twenty-five of forty-eight (52.1%) colonized patients carried C.albicans and 15/48 (31.25%) C.parapsilosis. We identified as risk factors for Candida spp. colonization: antibiotic therapy, parenteral nutrition, the use of a central venous catheter, and nasogastric tube. Our experience suggests that effective microbiological surveillance can allow for implementing proper, effective and timely control measures in a highrisk setting

Candida SPP. Colonization in NICU: A 2-Year Surveillance Study

Introduction: Fungal infections are an important cause of increased morbidity and mortality in infants admitted to neonatal intensive care units (NICUs). In VLBW infants, Candida (C.) albicans is the third most common cause of neonatal late onset sepsis (LOS). The overall incidence of candidemia in NICU is increasing because of the longer survival and the invasive procedures related with the intensive care of extremely preterm infants. Prevention of candidemia in neonates is supported by the identification and adequate management of specific risk factors, including low birth weight, use of invasive devices, prolonged hospitalization and use of broad-spectrum antimicrobial agents. Effective prophylactic strategies have recently become available, but the identification of the best possible strategies to manage high-risk infants is still a priority. Prior colonization is a key risk factor for candidemia. For this reason, surveillance studies to monitor incidence, species distribution, and antifungal susceptibility profiles are mandatory. Materials and Methods: In 2013 and 2014, we performed a cohort, prospective surveillance study in our NICU, collecting weekly nasal and rectal swabs. For each patient, clinical and demographic data expected to affect Candida colonization were recorded. We evaluated Candida spp. colonization rate and assessed the related risk factors. Swabs were placed on Sabouraud agar and incubated at 30°C for 4 days. Candida growth on agar was confirmed by microscopic observation. Moreover, Candida spp. were identified through Candida chromogenic agar (ChromAgar Candida, Laboratorios Conda) and API® 20C AUX (Biomérieux). Statistical analysis was performed by EpiInfo (CDC software) using the chi square or the Fisher’s exact method, when indicated. We assumed as statistically significant a p-value < 0.05. Results: In this 2-year study, we enrolled 520 patients and we analyzed 1,259 nasal and 1,255 rectal swabs. From 472 out of 520 patients we collected complete microbiological, clinical and demographic data. 48 out of 472 (10.17%) patients tested positive for Candida spp. at least once. In particular, 26 patients tested positive for C. albicans, 16 for C. parapsilosis, 6 for C. glabrata and 1 each for C. guilliermondii and an environmental mold. All the colonized patients had their rectal samples positive, and 7 their nasal samples as well. 15 patients out of 472 (3.18%) had more than one rectal or nasal swab positive during their NICU stay. Importantly, 9 patients out of 15 tested negative at the first sampling, suggesting that they have acquired Candida spp. colonization during their stay. Table 1 summarizes data about risk factors for Candida colonization in the patients under study. No systemic infection by Candida spp. was reported during the study. Conclusion: Our experience suggest that an effective microbiological surveillance can allow for implementing proper, effective and timely control measures in a high-risk setting

Is the monoclonal spread of the ST258, KPC-3-producing clone being replaced in southern Italy by the dissemination of multiple clones of carbapenem nonsusceptible, KPC-3-producing Klebsiella pneumoniae?

Spread of carbapenemase-producing Klebsiella pneumoniae has been identified as an issue of serious worldwide concern from clinical and public health perspectives. Italy is an country endemic for and a reservoir of K. pneumoniae carbapenemases (KPC). Nineteen isolates of CR-Kp from 16 different patients admitted in two hospital of Palermo in the period April-May 2014 were studied. Seven of 16 isolates belonged to ST307, six to ST258 and three to ST273. All isolates were KPC-3 producers. Our data emphasize the increasing difficulties in controlling the spread of KPC-K