Summary

This document discusses the human microbiome, including its components (microbes) in various body systems like the urinary tract, skin, and gut. It also covers research methods, such as studying microbe interactions via animal models.

Full Transcript

24.4 Urogenital Tracts and Their Microbes Altered conditions can cause Age and gender character of potential pathogens in the mrm urogenital tract infection urethra (such as Escherichia coli and Proteus mirabilis) to...

24.4 Urogenital Tracts and Their Microbes Altered conditions can cause Age and gender character of potential pathogens in the mrm urogenital tract infection urethra (such as Escherichia coli and Proteus mirabilis) to genderC multiply and cause disease. The two main causes for getting infection are poor _ hygiene and sexual \ _ intercourse. _ E. coli and P. mirabilis frequently cause urinary tract infections, which is more prevalent in women than in man. Hospital-acquired urinary tract infection In hospital-acquired Structure of a catheter urinary tract infection, particularly in catheterized or immunocompromised patients, a wide range of organisms otherwise apparently incapable of yukascandyfactory.com causing urinary tract infection may be involved. Lactobacillus in female genital tract The vagina of the adult female is weakly acidic and contains significant amounts of glycogen. Lactobacillus acidophilus, a resident organism in the vagina, ferments the glycogen (breaking down to glucose), producing lactic acid. Lactic acid maintains a local acidic environment. (b) Gram stain of Lactobacillus acidophilus, the predominant organism in the vagina of women. 24.5 The Skin and Its Microbes There are approximately 1 million resident bacteria per square centimeter of skin for a total of about 1010 skin microorganisms covering the average adult. The skin surface varies greatly in chemical composition and moisture content – three microenvironments (Figure 24.13) dry skin moist skin sebaceous skin 24.5 The Skin and Its Microbes Composition is influenced by – environmental factors (e.g., weather) – host factors (e.g., age (puberty), personal hygiene) – Each microenvironment shows a unique microbiota. 24.6 Human Study Groups and Animal Models Human Microbiome Study Groups have formed most of our understanding of the functions of the human microbiome. – The Human Microbiome Project (HMP) surveyed hundreds of medical students over several years to determine a baseline for healthy human microbiomes. https://www.hmpdacc.org/ The Human Microbiome Project Phase 1 - HMP1, 2008 through 2013, characterized the microbial communities from 300 healthy individuals. (Later projects showed the weakness in this model, as they revealed more diversity in non-US born subjects and lacked data on diet or other lifestyle attributes.) Phase 2 - Integrative Human Microbiome Project (iHMP), focusing on three different cohort studies of microbiome-associated conditions using multiple ‘omics’ technologies. – Pregnancy & Preterm Birth – Onset of Inflammatory Bowel Disease (IBD) – Onset of Type 2 Diabetes 24.6 Human Study Groups and Animal Models Mouse Models – Mice have a short life cycle and well-defined genetic lines; they can be raised in a germ-free environment. –antibiotic therapy –strict dietary control –fecal transplants –germ-free environment – There are still significant differences between mice and humans (Figure 24.16), although mice have been used to good effect to study human gut microbiome interactions. Mice have a larger cecum than humans. Most fermentation is completed in the mouse cecum, rather than the human large intestine. Figure 24.16 24.7 Colonization, Succession, and Stability of the Gut Microbiota Microbial Activities in the First Year of Life – Colonization begins at birth, with transfer from mother to infant. – Early colonizing microbes are a source of vitamins and tend to be facultative rather than obligate anaerobes. Variables determine the nature of the gut microbiome. – Vaginally born infants have a microbiome more similar to that of their mothers than those born via Cesarean section. – Breastfed infants have more commensal bacteria, as breast milk has oligosaccharides that promote their colonization. Stability of the Adult Microbiome and Transitions with Age – Early experiences determine gut microbiome. – Aging and frailty are associated with decreased microbial diversity.

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