Publications by authors named "M F Maiden"

419 Publications

Parallel sequencing reveals in commercial meat chickens less than 8 days old.

Appl Environ Microbiol 2021 Sep 22:AEM0106021. Epub 2021 Sep 22.

The Peter Medawar Building for Pathogen Research, Department of Zoology, University of Oxford, Oxford, UK.

from contaminated poultry meat is a major source of human gastroenteritis worldwide. To date, attempts to control this zoonotic infection with on-farm biosecurity measures have been inconsistent in outcome. A cornerstone of these efforts has been the detection of chicken infection with microbiological culture, where is generally not detectable until birds are at least 21 days old. Using parallel sequence based bacterial 16S profiling analysis and targeted sequencing of the gene, was identified at very low levels in all commercial flocks at less than 8 days old that were tested from the UK, Switzerland, and France. These young chicks exhibited a much greater diversity of types than older birds testing positive for by culture or qPCR. This suggests that, as the bacteria multiply sufficiently to be detected by culture methods, one or two variants, as indicated by type, dominate the infection. The findings that: (i) most young chicks carry some and (ii) not all flocks become positive by culture, suggest that efforts to control infection, and therefore avoid contamination of poultry meat, should concentrate on how to limit to low levels by the prevention of the overgrowth of single strains. Our results demonstrate the presence of DNA amongst faecal samples from a range of commercially reared meat chicks that are less than 8 days of age, consistent across 3 European countries. The recently developed, sensitive detection method indicates that infection occurs on commercial farms much earlier and more widely than previously thought, which opens-up new opportunities to control contamination at the start of the food-chain, and reduce the unacceptably high levels of human disease.
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http://dx.doi.org/10.1128/AEM.01060-21DOI Listing
September 2021

'B Part of It' School Leaver study: a repeat cross-sectional study to assess the impact of increasing coverage with meningococcal B (4CMenB) vaccine on carriage of Neisseria meningitidis.

J Infect Dis 2021 Sep 6. Epub 2021 Sep 6.

Vaccinology and Immunology Research Trials Unit, Women's and Children's Health Network, Adelaide, South Australia, Australia.

Background: Recombinant protein-based vaccines targeting serogroup B meningococci protect against invasive disease, but impacts on carriage are uncertain. This study assessed carriage prevalence of disease-associated meningococci from 2018-2020, as the proportion of vaccinated adolescents increased following introduction of a school-based 4CMenB immunisation program.

Methods: Eligible participants who completed high school (age 17-25) in South Australia in the previous year had an oropharyngeal swab taken and completed a risk factor questionnaire. Disease-associated meningococci (genogroups A, B, C, W, X, Y) were detected by meningococcal and genogroup-specific polymerase chain reaction.

Results: The final analysis included 4104 participants in 2018, 2690 in 2019, and 1338 in 2020. The proportion vaccinated with 4CMenB increased from 43% in 2018, to 78% in 2019, and 76% in 2020. Carriage prevalence of disease-associated meningococci in 2018 was 225/4104 (5.5%). There was little difference between the carriage prevalence in 2019 (134/2690, 5.0%, adjusted odds ratio [aOR] 0.82, 95% CI 0.64-1.05) and 2020 (68/1338, 5.1% aOR 0.82, 95% CI 0.57-1.17) compared to 2018.

Conclusions: Increased 4CMenB uptake in adolescents was not associated with a decline in carriage of disease-associated meningococci. 4CMenB immunisation programs should focus on direct (individual) protection for groups at greatest risk of disease.
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http://dx.doi.org/10.1093/infdis/jiab444DOI Listing
September 2021

Frailty is not independently associated with intensive care unit length of stay: An observational study.

Aust Crit Care 2021 Aug 27. Epub 2021 Aug 27.

Intensive Care Unit, University Hospital Geelong, Barwon Health, Victoria, Australia; Intensive Care Unit, Royal Adelaide Hospital, South Australia, Australia; Discipline of Acute Care Medicine, University of Adelaide, South Australia, Australia. Electronic address:

Background: Frailty is independently associated with morbidity and mortality in critically ill patients. However, the association between preadmission frailty and the degree of treatment received in the intensive care unit (ICU) remains unclear.

Objective: To describe patient length of stay in an ICU and the treatments provided according to the extent of patient frailty.

Methods: Single-centre retrospective cohort study of adult patients admitted to a tertiary ICU between January 2018 and December 2019. Frailty was assessed using the Clinical Frailty Scale (CFS). The primary outcome was ICU length of stay stratified by CFS score (1-8). Secondary outcomes were the proportion of patients with each CFS score treated with vasoactive agents, invasive ventilation, noninvasive ventilation, renal replacement therapy, and tracheostomy. Poisson regression and competing risks regression was used to analyse associations between ICU length of stay and potential confounders.

Results: The study cohort comprised 2743 patients, with CFS scores known for 2272 (83%). Length of stay in the ICU increased with each increment in the CFS up to a score of 5, beyond which it decreased with higher frailty scores. After adjusting for age, illness severity, admission type, and treatment limitation, CFS scores were not independently associated with length of stay in the ICU (P = 0.31). The proportion of patients receiving specific ICU treatments peaked at different CFS scores, being highest for vasoactive agents at CFS 5 (47%), invasive ventilation CFS 3 (51%), noninvasive ventilation CFS 6 (11%), renal replacement therapy CFS 6 (8.2%), and tracheostomy CFS 5 (2.2%). Increasing frailty was associated with increased mortality and discharge to a destination other than home.

Conclusions: The extent of frailty is not independently associated with length of stay in the ICU. The proportion of patients receiving specific ICU treatments peaked at different CFS scores.
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http://dx.doi.org/10.1016/j.aucc.2021.06.012DOI Listing
August 2021

A multicenter randomized clinical trial of pharmacological vitamin B1 administration to critically ill patients who develop hypophosphatemia during enteral nutrition (The THIAMINE 4 HYPOPHOSPHATEMIA trial).

Clin Nutr 2021 08 24;40(8):5047-5052. Epub 2021 Jul 24.

The University of Melbourne, Department of Critical Care, Melbourne Medical School, Melbourne, Australia; Intensive Care Unit, Royal Melbourne Hospital, Melbourne, Australia.

Background: Hypophosphatemia may be a useful biomarker to identify thiamine deficiency in critically ill enterally-fed patients. The objective was to determine whether intravenous thiamine affects blood lactate, biochemical and clinical outcomes in this group.

Method: This randomized clinical trial was conducted across 5 Intensive Care Units. Ninety critically ill adult patients with a serum phosphate ≤0.65 mmol/L within 72 h of commencing enteral nutrition were randomized to intravenous thiamine (200 mg every 12 h for up to 14 doses) or usual care (control). The primary outcome was blood lactate over time and data are median [IQR] unless specified.

Results: Baseline variables were well balanced (thiamine: lactate 1.2 [1.0, 1.6] mmol/L, phosphate 0.56 [0.44, 0.64] mmol/L vs. control: lactate 1.0 [0.8, 1.3], phosphate 0.54 [0.44, 0.61]). Patients randomized to the intervention received a median of 11 [7.5, 13.5] doses for a total of 2200 [1500, 2700] mg of thiamine. Blood lactate over the entire 7 days of treatment was similar between groups (mean difference = -0.1 (95 % CI -0.2 to 0.1) mmol/L; P = 0.55). The percentage change from lactate pre-randomization to T = 24 h was not statistically different (thiamine: -32 (-39, -26) vs. control: -24 (-31, -16) percent, P = 0.09). Clinical outcomes were not statistically different (days of vasopressor administration: thiamine 2 [1, 4] vs. control 2 [0, 5.5] days; P = 0.37, and deaths 9 (21 %) vs. 5 (11 %); P = 0.25).

Conclusions: In critically ill enterally-fed patients who developed hypophosphatemia, intravenous thiamine did not cause measurable differences in blood lactate or clinical outcomes.

Trial Registration: Australian and New Zealand Clinical Trials Registry (ACTRN12619000121167).
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http://dx.doi.org/10.1016/j.clnu.2021.07.024DOI Listing
August 2021

An evaluation of the species and subspecies of the genus Salmonella with whole genome sequence data: Proposal of type strains and epithets for novel S. enterica subspecies VII, VIII, IX, X and XI.

Genomics 2021 Sep 7;113(5):3152-3162. Epub 2021 Jul 7.

Public Health England, Gastrointestinal Bacteria Reference Unit, 61 Colindale Avenue, London NW9 5EQ, United Kingdom. Electronic address:

Species and subspecies within the Salmonella genus have been defined for public health purposes by biochemical properties; however, reference laboratories have increasingly adopted sequence-based, and especially whole genome sequence (WGS), methods for surveillance and routine identification. This leads to potential disparities in subspecies definitions, routine typing, and the ability to detect novel subspecies. A large-scale analysis of WGS data from the routine sequencing of clinical isolates was employed to define and characterise Salmonella subspecies population structure, demonstrating that the Salmonella species and subspecies were genetically distinct, including those previously identified through phylogenetic approaches, namely: S. enterica subspecies londinensis (VII), subspecies brasiliensis (VIII), subspecies hibernicus (IX) and subspecies essexiensis (X). The analysis also identified an additional novel subspecies, reptilium (XI). Further, these analyses indicated that S. enterica subspecies arizonae (IIIa) isolates were divergent from the other S. enterica subspecies, which clustered together and, on the basis of ANI analysis, subspecies IIIa was sufficiently distinct to be classified as a separate species, S. arizonae. Multiple phylogenetic and statistical approaches generated congruent results, suggesting that the proposed species and subspecies structure was sufficiently biologically robust for routine application. Biochemical analyses demonstrated that not all subspecies were distinguishable by these means and that biochemical approaches did not capture the genomic diversity of the genus. We recommend the adoption of standardised genomic definitions of species and subspecies and a genome sequence-based approach to routine typing for the identification and definition of novel subspecies.
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http://dx.doi.org/10.1016/j.ygeno.2021.07.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8426187PMC
September 2021
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