RESULTS:
1 - 3 of 3 for "Anne C. Midwinter"
Genomic epidemiology of extended-spectrum beta-lactamase-producing Escherichia coli from humans and a river in Aotearoa New Zealand
In Aotearoa New Zealand urinary tract infections in humans are commonly caused by extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli. This group of antimicrobial-resistant bacteria are often multidrug resistant. However there is limited information on ESBL-producing E. coli found in the environment and their link with human clinical isolates. In this study we examined the genetic relationship between environmental and human clinical ESBL-producing E. coli and isolates collected in parallel within the same area over 14 months. Environmental samples were collected from treated effluent stormwater and multiple locations along an Aotearoa New Zealand river. Treated effluent stormwater and river water sourced downstream of the treated effluent outlet were the main samples that were positive for ESBL-producing E. coli (7/14 samples 50.0%; 3/6 samples 50%; and 15/28 samples 54% respectively). Whole-genome sequence comparison was carried out on 307 human clinical and 45 environmental ESBL-producing E. coli isolates. Sequence type 131 was dominant for both clinical (147/307 47.9%) and environmental isolates (11/45 24.4%). Only one ESBL gene was detected in each isolate. Among the clinical isolates the most prevalent ESBL genes were bla CTX-M-27 (134/307 43.6%) and bla CTX-M-15 (134/307 43.6%). Among the environmental isolates bla CTX-M-15 (28/45 62.2%) was the most prevalent gene. A core SNP analysis of these isolates suggested that some strains were shared between humans and the local river. These results highlight the importance of understanding different transmission pathways for the spread of ESBL-producing E. coli.
Corynebacterium megadyptis sp. nov. with two subspecies, Corynebacterium megadyptis subsp. megadyptis subsp. nov. and Corynebacterium megadyptis subsp. dunedinense subsp. nov. isolated from yellow-eyed penguins
Novel Corynebacterium strains 3BT and 7BT were isolated from the oral cavities of young chicks of yellow-eyed penguins (hoiho) Megadyptes antipodes. A polyphasic taxonomic characterization of these strains revealed chemotaxonomic biochemical and morphological features that are consistent with those of the genus Corynebacterium . The 16S rRNA gene sequence similarity values between the strains and their closest phylogenetic neighbour Corynebacterium ciconiae CCUG 47525T were 99.07 % values that are in line with their phylogenomic positions within the evolutionary radiation of the genus Corynebacterium . Digital DNA–DNA hybridization values and average nucleotide identities between the genome sequences of the two strains and related Corynebacterium species were well below the defined threshold values (70 and 95–96 % respectively) for prokaryotic species delineation. The genome size of these strains varied between 2.45–2.46 Mb with G+C content 62.7–62.9 mol%. Strains 3BT and 7BT were Gram-stain positive bacilli that were able to grow in presence of 0–10 % (w/v) NaCl and at temperature ranging between 20–37 °C. The major fatty acids (>15 %) were C16 : 0 and C18 : 1 ω9c and the mycolic acid profile included 32–36 carbon atoms. We propose that these strains represent a novel species Corynebacterium megadyptis sp. nov. with 3BT (=DSM 111184T=NZRM 4755T) as the type strain. Phylogenomically strains 3BT and 7BT belong to two lineages with subtle differences in MALDI-TOF spectra chemotaxonomic profiles and phenotypic properties. The fatty acid profile of strain 3BT contains C18 : 0 as a predominant type (>15 %) which is a minor component in strain 7BT. Strain 7BT can oxidize N-acetyl-d-glucosamine l-serine α-hydroxy-butyric acid l-malic acid l-glutamic acid bromo-succinic acid and l-lactic acid characteristics not observed in strain 3BT. Therefore we propose that these strains represent two subspecies namely Corynebacterium megadyptis subsp. megadyptis subsp. nov. (type strain 3BT=DSM 111184T=NZRM 4755T) and Corynebacterium megadyptis subsp. dunedinense subsp. nov. (type strain 7BT=DSM 111183T=NZRM 4756T).
Genomic correlates of extraintestinal infection are linked with changes in cell morphology in Campylobacter jejuni
Campylobacter jejuni is the most common cause of bacterial diarrheal disease in the world. Clinical outcomes of infection can range from asymptomatic infection to life-threatening extraintestinal infections. This variability in outcomes for infected patients has raised questions as to whether genetic differences between C. jejuni isolates contribute to their likelihood of causing severe disease. In this study we compare the genomes of ten C. jejuni isolates that were implicated in extraintestinal infections with reference gastrointestinal isolates in order to identify unusual patterns of sequence variation associated with infection outcome. We identified a collection of genes that display a higher burden of uncommon mutations in invasive isolates compared with gastrointestinal close relatives including some that have been previously linked to virulence and invasiveness in C. jejuni . Among the top genes identified were mreB and pgp1 which are both involved in determining cell shape. Electron microscopy confirmed morphological differences in isolates carrying unusual sequence variants of these genes indicating a possible relationship between extraintestinal infection and changes in cell morphology.