Publications by authors named "Simon C Andrews"

The gut microbiota residing in the distal ileum and colon is the most complex, diverse, and densest microbial ecosystem in the human body. Despite its known role in human health and disease, gut microbiome diversity and function are rarely explored in vulnerable populations such as refugees. The current study aimed to explore gut microbiota diversity and sources of variation among adolescent Afghan refugees residing in Peshawar, Pakistan.

View Article and Find Full Text PDF

Iron is essential for many physiological functions of the body, and it is required for normal growth and development. Iron deficiency (ID) is the most common form of micronutrient malnutrition and is particularly prevalent in infants and young children in developing countries. Iron supplementation is considered the most effective strategy to combat the risk of ID and ID anaemia (IDA) in infants, although iron supplements cause a range of deleterious gut-related problems in malnourished children.

View Article and Find Full Text PDF

Ferritins are multimeric cage-forming proteins that play a crucial role in cellular iron homeostasis. All H-chain-type ferritins harbour a diiron site, the ferroxidase centre, at the centre of a 4 α-helical bundle, but bacterioferritins are unique in also binding 12 hemes per 24 meric assembly. The ferroxidase centre is known to be required for the rapid oxidation of Fe during deposition of an immobilised ferric mineral core within the protein's hollow interior.

View Article and Find Full Text PDF

is a common colonizer of the human gut and in doing so it must be able to resist the actions of the host's innate defences. Bile salts are a class of molecules that possess potent antibacterial activity that control growth. Bacteria that colonize and survive in that niche must be able to resist the action of bile salts, but the mechanisms by which does so are poorly understood.

View Article and Find Full Text PDF

Although iron is an essential nutrient for humans, as well as for almost all other organisms, it is poorly absorbed (~15%) from the diet such that most passes through the upper gut into the large intestine. The colonic microbiota is thus exposed to, and potentially influenced by, such residual iron which could have an impact on human health. The aim of the research described here is to determine how the major forms of dietary iron (inorganic iron and haem) influence metabolic activity and composition of the human gut microbiota by utilizing an parallel, pH-controlled anaerobic batch culture approach.

View Article and Find Full Text PDF

Iron deficiency is the most prevalent human micronutrient deficiency, disrupting the physiological development of millions of infants and children. Oral iron supplementation is used to address iron-deficiency anemia and reduce associated stunting but can promote infection risk since restriction of iron availability serves as an innate immune mechanism against invading pathogens. Raised iron availability is associated with an increase in enteric pathogens, especially Enterobacteriaceae species, accompanied by reductions in beneficial bacteria such as Bifidobacteria and lactobacilli and may skew the pattern of gut microbiota development.

View Article and Find Full Text PDF

Introduction: Tuberculosis (TB) caused by is a common infectious disease associated with significant morbidity and mortality, especially in low-income and middle-income countries. Successful treatment of the disease requires prolonged intake (6-8 months) of multiple antibiotics with potentially detrimental consequences on the composition and functional potential of the human microbiome. The protocol described in the current study aims to identify microbiome (oral and gut) signatures associated with TB pathogenesis, treatment response and outcome in humans.

View Article and Find Full Text PDF

A growing body of research evidence suggests that elevated homocysteine level (hyperhomocysteinemia) is an independent risk factor for cardiovascular diseases. The current study aimed to investigate the prevalence and associated risk factors for hyperhomocysteinemia among adolescent Afghan refugees aged 10−19 years. In total, 206 healthy adolescent boys and girls were randomly recruited from a refugee village in Peshawar, Pakistan, in 2020.

View Article and Find Full Text PDF

EfeUOB/M has been characterised in Pseudomonas syringae pathovar. syringae as a novel type of ferrous-iron transporter, consisting of an inner-membrane protein (EfeU) and three periplasmic proteins (EfeO, EfeM and EfeB). The role of an iron permease and peroxidase function has been identified for the EfeU and EfeB proteins, respectively, but the role of EfeO/M remains unclear.

View Article and Find Full Text PDF

Pakistan has hosted millions of Afghan refugees over the last several decades. Due to poor socioeconomic status, food insecurity and inadequate access to health care, these refugees are considered to be at high risk of malnutrition. Previous studies on nutritional assessment of high-risk populations (refugees) have focused mainly on women and children (0-59 months).

View Article and Find Full Text PDF

Objectives: ST11 is a high-risk sequence type associated with carbapenem-resistant Klebsiella pneumoniae strains. Carbapenemase-producing hypervirulent K. pneumoniae (hvKp) are a major concern as they harbour a diverse range of pathogenicity traits.

View Article and Find Full Text PDF

Eggs are a whole food which affordably support human nutritional requirements worldwide. Eggs strongly resist bacterial infection due to an arsenal of defensive systems, many of which reside in the egg white. However, despite improved control of egg production and distribution, eggs remain a vehicle for foodborne transmission of serovar Enteritidis, which continues to represent a major public health challenge.

View Article and Find Full Text PDF
Article Synopsis
  • Iron deficiency is the most prevalent micronutrient deficiency globally, and its impact on immunity, especially adaptive immunity, is unclear, prompting the study of its effects through various experimental models.* -
  • Research demonstrated that low iron levels, caused by increased hepcidin, significantly hinder immune responses to vaccinations and viral infections in both animal models and humans, indicating a critical role of iron in T cell and antibody function.* -
  • The findings suggest that while hypoferremia serves as an innate response to infection, it can negatively affect the development of adaptive immunity, highlighting the need to address iron deficiency to enhance vaccine efficacy and overall immune health in various populations.*
View Article and Find Full Text PDF

A recent work revealed that egg white (EW) at 45 °C exhibits powerful bactericidal activity against serovar Enteritidis, which is surprisingly little affected by removal of the >10 kDa EW proteins. Here, we sought to identify the major EW factors responsible for this bactericidal activity by fractionating EW using ultrafiltration and nanofiltration and by characterizing the physicochemical and antimicrobial properties of the resulting fractions. In particular, 22 peptides were identified by nano-LC/MS-MS and the bactericidal activities of representative peptides (with predicted antimicrobial activity) were further assessed.

View Article and Find Full Text PDF

Background: The emergence of carbapenem-resistant and hypervirulent hypermucoviscous strains poses a significant public health challenge. We determined the MDR profiles, antibiotic resistance factors, virulence gene complement, and hypermucoviscous features of 200 clinical isolates from two major tertiary care hospitals in Islamabad and Rawalpindi, Pakistan.

Methods: Susceptibility profiling and phenotypic analysis were performed according to the CLSI guidelines.

View Article and Find Full Text PDF

serovar Enteritidis is noted for its ability to survive the harsh antibacterial activity of egg white which is presumed to explain its occurrence as the major food-borne pathogen associated with the consumption of eggs and egg products. Liquid egg white is a major ingredient for the food industry but, because of its thermal fragility, pasteurization is performed at the modest temperature of 57°C (for 2-6 min). Unfortunately, such treatment does not lead to sufficient reduction in Enteritidis contamination, which is a clear health concern when the product is consumed without cooking.

View Article and Find Full Text PDF

Enteritidis is the most prevalent food-borne pathogen associated with egg-related outbreaks in the European Union. During egg colonization, Enteritidis must resist the powerful anti-bacterial activities of egg white (EW) and overcome ovotransferrin-imposed iron-restriction (the most important anti-bacterial mechanism of EW). Many pathogens respond to iron restriction by secreting iron-chelating chemicals called siderophores but EW contains a siderophore-sequestering "lipocalin" protein (Ex-FABP) that is predicted to limit the usefulness of siderophores in EW.

View Article and Find Full Text PDF

24FS is a bacteriocin-producing, multiply antibiotic-resistant, and potentially virulent bacterium isolated from healthy infant feces. The draft 2.9-Mb genome sequence revealed 2,968 protein-encoding genes; 11 antibiotic resistance, 8 virulence, and 3 bacteriocin genes; and 2 plasmids, 4 prophages, 30 insertion sequence (IS) elements, 1 transposon, and 1 integron.

View Article and Find Full Text PDF

Salmonella enterica serovar Enteritidis (SE) is the most frequently-detected Salmonella in foodborne outbreaks in the European Union. Among such outbreaks, egg and egg products were identified as the most common vehicles of infection. Possibly, the major antibacterial property of egg white is iron restriction, which results from the presence of the iron-binding protein, ovotransferrin.

View Article and Find Full Text PDF

Objectives: Enterococci are Gram-positive lactic acid bacteria and common inhabitants of the gastrointestinal tract of mammals, including humans. They are also widely distributed in diverse environments such as soil, water, vegetables and food. Enterococcus faecium is able to produce antimicrobial compounds (enterocins) and thus can act as a probiotic.

View Article and Find Full Text PDF

Objectives: Uropathogenic Escherichia coli (UPEC) is the leading cause of urinary tract infections (UTIs). The pandemic sequence type 131 (ST131) clonal group is associated with multidrug resistance and virulence. Here we report the first draft genome of a ST131-O25b-H30 strain from Pakistan, isolated from a patient with community-acquired UTI.

View Article and Find Full Text PDF

The RIC (repair of iron clusters) protein of is a di-iron hemerythrin-like protein that has a proposed function in repairing stress-damaged iron-sulfur clusters. In this work, we performed a bacterial two-hybrid screening to search for RIC-protein interaction partners in As a result, the NA-binding rotein from tarved cells (Dps) was identified, and its potential interaction with RIC was tested by bacterial adenylate cyclase-based two-hybrid (BACTH) system, bimolecular fluorescence complementation, and pulldown assays. Using the activity of two Fe-S-containing enzymes as indicators of cellular Fe-S cluster damage, we observed that strains with single deletions of or have significantly lower aconitase and fumarase activities.

View Article and Find Full Text PDF

10CH is a bacteriocin-producing potential probiotic lactic acid bacterium (LAB) strain isolated from cheese. Its complete nucleotide sequence shows a single circular chromosome of 3.3 Mb, with a G+C content of 44.

View Article and Find Full Text PDF

Chicken egg white protects the embryo from bacterial invaders by presenting an assortment of antagonistic activities that combine together to both kill and inhibit growth. The key features of the egg white anti-bacterial system are iron restriction, high pH, antibacterial peptides and proteins, and viscosity. serovar Enteritidis is the major pathogen responsible for egg-borne infection in humans, which is partly explained by its exceptional capacity for survival under the harsh conditions encountered within egg white.

View Article and Find Full Text PDF