Genomic characterisation of multidrug-resistant Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii in two intensive care units in Hanoi, Viet Nam: a prospective observational cohort study.

BACKGROUND: Viet Nam has high rates of antimicrobial resistance (AMR) but little capacity for genomic surveillance. This study used whole genome sequencing to examine the prevalence and transmission of three key AMR pathogens in two intensive care units (ICUs) in Hanoi, Viet Nam. METHODS: A prospective surveillance study of all adults admitted to ICUs at the National Hospital for Tropical Diseases and Bach Mai Hospital was done between June 19, 2017, and Jan 16, 2018. Clinical and environmental samples were cultured on selective media, characterised with MALDI TOF mass spectrometry, and sequenced with Illumina. Phylogenies based on the de-novo assemblies (SPAdes) were constructed with MAFFT (PARsnp), Gubbins, and RAxML. Resistance genes were detected with Abricate against the US National Center for Biotechnology Information database. FINDINGS: 3153 Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii isolates from 369 patients were analysed. Phylogenetic analysis revealed predominant lineages within A baumannii (global clone 2, sequence types ST2 and ST571) and K pneumoniae (ST15, ST16, ST656, ST11, and ST147) isolates. Isolation from stool was most common with E coli (87·0%) followed by K pneumoniae (62·5%). Of the E coli, 85·0% carried a blaCTX-M variant, while 81·8% of K pneumoniae isolates carried blaNDM (54·4%), or blaKPC (45·1%), or both. Transmission analysis with single nucleotide polymorphisms identified 167 clusters involving 251 (68%) of 369 patients, in some cases involving patients from both ICUs. There were no clear differences between the lineages or AMR genes recovered between the two ICUs. INTERPRETATION: This study represents the largest prospective surveillance study of key AMR pathogens in Vietnamese ICUs. Clusters of closely related isolates in patients across both ICUs suggests recent transmission before ICU admission in other health-care settings or in the community. FUNDING: UK Medical Research Council Newton Fund, Viet Nam Ministry of Science and Technology, Wellcome Trust, Academy of Medical Sciences, Health Foundation, and UK National Institute for Health and Care Research Cambridge Biomedical Research Centre.

In situ compatibilizer-reinforced interface between a flexible polymer (a functionalized polypropylene) and a rodlike polymer (a thermotropic liquid crystalline polymer).

We present an investigation of the interfacial reinforcement between a flexible folded-chain polymer (functionalized polypropylene-maleic anhydride-grafted polypropylene, MAPP) and a rodlike polymer (a themotropic liquid crystalline polymer, TCLP - poly(ester amide)). Fracture toughness was measured using an asymmetric double-cantilever beam test (ADCB). High fracture toughness at the bonding temperature of 200 degrees C indicates that a chemical reaction has occurred at the interface to provide a strong interaction between MAPP and TLCP. Despite the higher modulus of TLCP, the fracture was propagated in the TLCP phase because of inherent TLCP domain structure. An analysis on the locus of failure revealed that at constant bonding temperature the fracture toughness between MAPP and TLCP was influenced not only by the bonding temperature but also by the bonding time. The fracture toughness increased with the bonding temperature until 200 degrees C was reached and then decreased at higher bonding temperature. The fracture toughness increased with annealing time until it reached a plateau value. We ascribe the dependence of the fracture toughness on the bonding time to the progressive occurrence of two different failure mechanisms, adhesive failure and cohesive failure. The adhesive strength increased with bonding temperature whereas the cohesive strength decreased because of weaker adhesion between TLCP crystalline domains. The dependence of fracture toughness on bonding time was explained in terms of the TLCP crystalline domain structure.