Deka, N. | Search bioRxiv

bioRxiv2023

Incidences of Helicobacter infection in pigs and tracing occupational hazard in pig farmers

Helicobacter species (H. sp.) is a gram-negative spiral-shaped motile bacteria that causes gastritis in pigs and also colonizes the human stomach. The current study seeks to assess the prevalence of various H. sp. in the gastric mucosa of slaughtered and dead pigs, as well as the prevalence of Helicobacter infection among pig farmers. A total of 403 stomach samples from various pig slaughter points, 74 necropsy samples from various pig farms and 97 stool samples from pig farmers were collected from Assam, India. Among 477 pig stomach samples tested, 214 samples with gastritis (20.09%) showed Gram negative, spiral-shaped organisms in brush cytology from the mucosal surface, and the rest of the 263 stomach samples without any gastric lesion showed only 3.04% Gram negative, spiral-shaped organisms. In ultrastructure investigation, Scanning Electron Microscopy (SEM) of the four urease positive stomach samples revealed a tightly coiled Helicobacter bacterium (spiral-shaped) found in the mucous lining of the stomach. In histopathological examination of pars esophagia, cardiac and fundic mucosa showed chronic gastritis associated with hemorrhagic necrosis, leucocytic infiltration with neutrophils and macrophages, and lymphoid aggregates (lymphoid follicles) etc. PCR confirmed 16S rRNA genes of Helicobacter suis (H. suis) where a total of 42 (19.63%) out of 214 pig stomach samples and 2 (2.08%) out of 96 stool samples of pig farmers were found positive for H. suis. of these 96 stool samples of pig farmers 3 (3.12%) were confirmed positive for Helicobacter pylori (H. pylori) Phosphoglucosamine mutase gene in PCR. Phylogenic analysis of the 16S rRNA gene of H. suis showed distinct clusters with other H. sp. In conclusion, this study provides evidence for the prevalence of Helicobacter both in pig gastric mucosa and human stool. The findings highlight the need for improved sanitation and hygiene practices among pig farmers to minimize the risk of Helicobacter infection in humans.

microbiology↗

bioRxiv2022

Preferential catabolism of L- vs D-serine by Proteus mirabilis contributes to pathogenesis and catheter-associated urinary tract infection

Proteus mirabilis is a common cause of urinary tract infection, especially in catheterized individuals. Amino acids are the predominant nutrient for bacteria during growth in urine, and our prior studies identified several amino acid import and catabolism genes as fitness factors for P. mirabilis catheter-associated urinary tract infection (CAUTI), particularly D- and L-serine. In this study, we sought to determine the hierarchy of amino acid utilization by P. mirabilis and to examine the relative importance of D- vs L-serine catabolism for critical steps in CAUTI development and progression. Herein, we show that P. mirabilis preferentially catabolizes L-serine during growth in human urine, followed by D-serine, threonine, tyrosine, glutamine, tryptophan, and phenylalanine. Independently disrupting catabolism of either D- or L-serine has minimal impact on in vitro phenotypes while completely disrupting both pathways decreases motility, biofilm formation, and fitness due to perturbation of membrane potential and cell wall biosynthesis. In a mouse model of CAUTI, loss of either serine catabolism system decreased fitness, but disrupting L-serine catabolism caused a greater fitness defect than disrupting D-serine catabolism. We therefore conclude that hierarchical utilization of amino acids may be a critical component of P. mirabilis colonization and pathogenesis within the urinary tract. Abbreviated SummaryAmino acids are a predominant nutrient in urine, and their import and catabolism has been hypothesized to contribute to the ability of bacteria to cause urinary tract infection. We demonstrate that a common uropathogen, Proteus mirabilis, preferentially catabolizes L-serine followed by D-serine, threonine, tyrosine, and glutamine during growth in human urine. We further demonstrate that L-serine catabolism provides a greater fitness advantage than D-serine catabolism, yet both pathways contribute to pathogenesis in the urinary tract. Graphical Abstract(Created using BioRender.com) O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/494593v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@13f3286org.highwire.dtl.DTLVardef@e0e84org.highwire.dtl.DTLVardef@db2946org.highwire.dtl.DTLVardef@72b421_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗