Clonal emergence of Klebsiella pneumoniae ST14 co-producing OXA-48-type and NDM carbapenemases with high rate of colistin resistance in Dubai, United Arab Emirates

© 2018 Elsevier Ltd Few studies have addressed the molecular epidemiology of carbapenem-resistant Enterobacteriaceae (CRE) isolates in the Arabian Peninsula, and such investigations have been missing from Dubai, a major economical, tourism and medical centre of the region. The antibiotic susceptibility, the carbapenemase type produced, and the clonality of 89 CRE strains isolated in five major Dubai hospitals in June 2015 to June 2016 were determined. Thirty-three percent of the collection of 70 Klebsiella pneumoniae, 13 Escherichia coli and 6 other Enterobacteriaceae were extremely drug resistant, 27% were resistant to colistin, and 4.5% (4 K. pneumoniae isolates) were resistant to all antibiotics tested. The colistin resistance rate in K. pneumoniae was 31.4%. None of the isolates carried mobile colistin resistance genes. Seventy-seven isolates produced carbapenemase: 53.3% OXA-48-like, 24.7% NDM and 22.1% both OXA-48-like and NDM, respectively. Pulsed-field gel electrophoresis clustered 50% of K. pneumoniae into a 35-membered group, which showed significant association with double carbapenemase production, with extreme drug resistance, and with being isolated from Emirati patients. Members of the cluster belonged to sequence type ST14. The rate of colistin resistance in K. pneumoniae ST14 was 37.1% vs. 27.1% of K. pneumoniae isolates outside of the cluster. Two of the panresistant K. pneumoniae isolates also belonged to ST14, whereas the other two were ST15 and ST231, respectively. In conclusion, beyond the overall high colistin resistance rate in CRE, the emergence of a highly resistant clone of K. pneumoniae ST14 in all Dubai hospitals investigated is a serious problem requiring immediate attention

A Comparative Study of Unbuffered Interconnection Networks Based on Crosspoint Complexity

Delta networks are less complex than crossbar switches, but they suffer from blocking which severely degrades their throughput performance. In this paper, we compare three delta-based networks (namely, the replicated delta network, the dilated delta network, and the expanded delta network), with two crossbar-based networks (namely, the replicated crossbar switch and the expanded crossbar switch). Our comparisons are based on the minimum crosspoint complexity required to achieve given targets of maximum throughput. Two policies for packets successfully reaching the output side of a network are considered: singleand multiple-acceptance. Many interesting findings are reported. First, the expanded delta network appears to be a very good choice in terms of crosspoint complexity. Also, unless very high maximum throughputs are targeted, the replicated delta network outperforms the dilated delta network. Finally, a crossbarbased switch could have less crosspoint complexity than all or some of ..

Secured operating regions of Slotted ALOHA in the presence of interfering signals from other networks and DoS attacking signals

It is expected that many networks will be providing services at a time in near future and those will also produce different interfering signals for the current Slotted ALOHA based systems. A random packet destruction Denial of Service (DoS) attacking signal can shut down the Slotted ALOHA based networks easily. Therefore, to keep up the services of Slotted ALOHA based systems by enhancing the secured operating regions in the presence of the interfering signals from other wireless systems and DoS attacking signals is an important issue and is investigated in this paper. We have presented four different techniques for secured operating regions enhancements of Slotted ALOHA protocol. Results show that the interfering signals from other wireless systems and the DoS attacking signals can produce similar detrimental effect on Slotted ALOHA. However, the most detrimental effect can be produced, if an artificial DoS attack can be launched using extra false packets arrival from the original network. All four proposed secured operating regions enhancement techniques are easy to implement and have the ability to prevent the shutdown of the Slotted ALOHA based networks

Wireless access to the global Internet: mobile radio networks and satellite systems

Guest Editoria

Inter-and-intra data center VM-placement for energy-efficient large-Scale cloud systems

Data centers play the crucial role in the delivery of Cloud services by enabling on-demand access to the shared resources such as software, platform, and infrastructure. Virtual Machine (VM) allocation is one of the challenging tasks in the data center management since user requirements, typically expressed as SLAs, have to be met with the minimum operational expenditure. Despite their huge processing and storage facilities, data centers are among the major contributors of the GreenHouse Gas (GHG) emissions of the IT services. In this paper, we propose a holistic approach for a large-scale Cloud system where the Cloud services are provisioned by several data centers interconnected over the backbone network. We propose a Mixed Integer Linear Programming (MILP) formulation that aims at virtualizing the backbone topology and placing the VMs in data centers with the objective of minimum power consumption. We compare our proposed solution with a benchmark MILP model which selects the closest data centers that can accommodate the user requests taking into account the CPU, memory, and bandwidth capacities of the residing physical hosts. Collected experimental results show the benefit of the proposed management scheme in terms of power consumption, resource utilization, and fairness for medium size data centers