Biology subjects

Bronowski, C.

Publications and source records attributed to Bronowski, C..

2 recordsLinked to original sources

bioRxiv2024

Sex Hormones Alter Pseudomonas aeruginosa Iron Acquisition and Virulence Factors

Urinary Tract Infections (UTI) are one of the most widespread infections in healthcare and community settings worldwide. Pseudomonas aeruginosa is the third most common pathogen associated with catheter-associated UTI (CAUTI). P. aeruginosa infections are highly resistant and difficult to treat and it is currently classified as priority 1 by the World Health Organisation. In vitro studies of microbes typically employ laboratory media. The inadequacy of nutrient-rich media in simulating the physiological environment has led to the development of multiple media that mimic human body fluids, including Artificial Urine Medium (AUM). By studying growth and in vitro biofilm assays along with proteomics, we sought to establish whether UTI P. aeruginosa respond differently in laboratory media, AUM and urine. To further probe the impact of environmental influences, sex hormones estradiol, progesterone and testosterone were added at physiologically relevant concentrations. The proteomic profiles were then compared between hormone supplemented AUM and urine. Our findings indicate that bacterial responses in standard laboratory media, AUM and urine were distinct. Increased proteins associated with iron acquisition mechanisms were similar in both AUM and urine. However, differences were observed in other virulence and iron pathways, such as phenazine production. Treatment with hormones decreased the abundance of P. aeruginosa proteins involved in iron acquisition. Individual hormones exhibited specific bacterial alterations. The presence of estradiol increased protein abundance of the Pseudomonas Quinolone Signal (PQS) quorum sensing system. This study suggests that P. aeruginosa pathogenesis in UTI infections may be influenced by the presence of specific hormones in the host. Understanding the individual role of host factors could contribute to a personalised treatment approach based on the potential impact on infection susceptibility and outcome.

microbiology↗

bioRxiv2017

Campylobacter jejuni transcriptome changes during loss of culturability in water

BackgroundThe natural environment serves as a potential reservoir for Campylobacter, the leading cause of bacterial gastroenteritis in humans. However, little is understood about the mechanisms underlying variations in survival characteristics between different strains of C. jejuni in natural environments, including water.\n\nResultsWe identified three Campylobacter jejuni strains that exhibited variability in their ability to retain culturability after suspension in water at two different temperatures (4{degrees}C and 25{degrees}C). Of the three, strains C. jejuni M1 exhibited the most rapid loss of culturability whilst retaining viability. Using RNAseq transcriptomics, we characterised C. jejuni M1 gene expression in response to suspension in water by analyzing bacterial suspensions recovered immediately after introduction into water (Time 0), and from two sampling time/temperature combinations where considerable loss of culturability was evident, namely (i) after 24 h at 25{degrees}C, and (ii) after 72 h at 4{degrees}C. Transcript data were compared with a culture-grown control. Some gene expression characteristics were shared amongst the three populations recovered from water, with more genes being up-regulated than down. Many of the up-regulated genes were identified in the Time 0 sample, whereas the majority of down-regulated genes occurred in the 25{degrees}C (24 h) sample.\n\nConclusionsVariations in expression were found amongst genes associated with oxygen tolerance, starvation and osmotic stress. However, we also found upregulation of flagellar assembly genes, accompanied by down-regulation of genes involved in chemotaxis. Our data also suggested a switch from secretion via the sec system to via the tat system, and that the quorum sensing gene luxS may be implicated in the survival of strain M1 in water. Variations in gene expression also occurred in accessory genome regions. Our data suggest that despite the loss of culturability, C. jejuni M1 remains viable and adapts via specific changes in gene expression.

microbiology↗