Clonal expansion and rapid characterization of Klebsiella pneumoniae ST1788, an otherwise uncommon strain spreading in Wales, UK.

A multidrug-resistant strain of Klebsiella pneumoniae (Kp) sequence type (ST) 1788, an otherwise uncommon ST worldwide, was isolated from 65 patients at 11 hospitals and 11 general practices across South and West Wales, UK, between February 2019 and November 2021. A collection of 97 Kp ST1788 isolates (including 94 from Wales) was analysed to investigate the diversity and spread across Wales and to identify molecular marker(s) to aid development of a strain-specific real-time PCR. Whole genome sequencing (WGS) was performed with Illumina technology and the data were used to perform phylogenetic analyses. Pan-genome analysis of further Kp genome collections was used to identify an ST1788-specific gene target; a real-time PCR was then validated against a panel of 314 strains and 218 broth-enriched screening samples. Low genomic diversity was demonstrated amongst the 94 isolates from Wales. Evidence of spread within and across healthcare facilities was found. A yersiniabactin locus and the KL2 capsular locus were identified in 85/94 (90.4 %) and 94/94 (100 %) genomes respectively; bla SHV-232, bla TEM-1, bla CTX-M-15 and bla OXA-1 were simultaneously carried by 86/94 (91.5 %) isolates; 4/94 (4.3 %) isolates also carried bla OXA-48 carbapenemase. Aminoglycoside and fluoroquinolone resistance markers were found in 94/94 (100 %) and 86/94 (91.5 %) isolates respectively. The ST1788-specific real-time PCR was 100 % sensitive and specific. Our analyses demonstrated recent clonal expansion and spread of Kp ST1788 in the community and across healthcare facilities in South and West Wales with isolates carrying well-defined antimicrobial resistance and virulence markers. An ST1788-specific marker was also identified, enabling rapid and reliable preliminary characterization of isolates by real-time PCR. This study confirms the utility of WGS in investigating novel strains and in aiding proactive implementation of molecular tools to assist infection control specialists.

A compact E × B filter: A multi-collector cycloidal focusing mass spectrometer.

A compact E × B mass spectrometer is presented. The mass spectrometer presented is termed a "perfect focus" mass spectrometer as the resolution of the device is independent of both the initial direction and energy of the ions (spatial and energy independent). The mass spectrometer is small in size (∼10.7 in.(3)) and weight (∼2 kg), making it an attractive candidate for portability when using small, permanent magnets. A multi-collector Faraday cup design allows for the detection of multiple ion beams in discrete collectors simultaneously; providing the opportunity for isotope ratio monitoring. The mass resolution of the device is around 400 through narrow collector slits and the sensitivity of the device follows expected theoretical calculations of the ion current produced in the electron impact ion source. Example mass spectra obtained from the cycloidal focusing mass spectrometer are presented as well as information on mass discrimination based on instrumental parameters and isotope ratio monitoring of certain ion signals in separate Faraday cups.