Typed lecture notes covering the rest of chapter 26 (Microbial Disease II) of Microbiology: An Evolving Science, the textbook used in the "General Microbiology" course (BioM122) at UCI. Aligns with lecture 23.
Microbial Disease II (Ch.26 continued, Lec. 23)
Monday, December 7, 2020 10:13 PM
• How does the intestine restore its bacterial pop after being decimated by diarrhea/antibiotic treatment?
H. Pylori
• In 1980s, Australian scientists discovered that bacteria H. pylori, not stress/spicy foods, cause ulcers.
• Secretes urease: urea -> NH4+ (neutralizes stomach acid)
• Enzymes collagenase and mucinase soften the mucous lining. -> allows bacteria to burrow into the mucous layer and reach the epithelial lining.
• They grow/divide, causing tissue damage. Associated w ulcers AND gastric cancer.
• H pylori is a normal gut microbe.
• There are protozoans that also cause diarrhea.
• Ex. Giardia lamblia -> major cause of giardiasis(diarrhea) around the world.
• Hepatitis: inflammation of the liver. 3 main hepatitis viruses that infect the liver:
○ Hep A: -sense ssRNA
○ Hep B: dsDNA virus
○ Hep C: +sense ssRNA virus
26.4: Genitourinary Tract Infections
• Genital and urinary tract are usually grouped together when discussing infections bc of their close proximity, yet few pathogens can infect both organ
systems.
• Viruses and Gram (-) bacteria are capable of infecting the genital tract. Yet viruses rarely cause UTIs.
• UT: kidneys, ureters, urinary bladder, urethra.
• Active UTIs occur:
○ Infection from urethra to bladder, deposition of bacteria from the blood to the kidney, descending infection from the kidneys, or ascending
infection from the kidneys.
• Urine is bacteriostatic(does not promote the growth of bacteria) to most commensal organisms living in the perineum/vagina.
• Most common agents of UTIs are mainly serotypes of E. coli (75%).
Uropathogenic E. coli
• Invade the bladder from the urethra. -> cause compact, intracellular biofilms -> recurrent bladder infections, esp in women.
• Have P-type pili, w/ a terminal receptor for the P antigen.
• Have 5 unique pathogenicity islands.
STDs
• Pathogens involved are susceptible to drying out -> they require direct physical contact w/ mucous membranes for transmission.
• Syphilis: caused by spirochete Treponema pallidum, yet can be treated w/ antibiotics.
○ Comes w/ dif stages of consequences-- primary syphilis is chancre @ site of infection, secondary is generalized rash, and tertiary is effects on
heart/CNS.
• Chlamydia: caused by Gram-neg bacteria Chlamydia trachomatis and Chlamydia pneumoniae (obligate intracellular pathogens that also cause
pneumonia and trachoma of eye).
○ If left untreated, can cause serious problems in males and females.
○
• Gonorrhea: caused by Gram-neg diplococcus Neisseria gonorrhea.
○ Binds o CD4+T cells, inhibiting T-cell activation.
○ Most infected men exhibit symptoms, whereas most women are asymptomatic.
○ Has become antibiotic-resistant over the decades.
• AIDS (lec17)
○ Graph indicates that over the last 10yrs there have been less deaths due to AIDS and over the last 25yrs less HIV infections.
○ Cuplike fungus Pneumocystis jirovecii is an opportunistic infection of the lungs.
○ Kaposi's sarcoma-- dark oval spots appearing on skin; cancer that arises only when immune system is not healthy.
• Trichomoniasis: caused by Trichomonas vaginalis (a flagellated protozoan, transmitted via trophozoite stage).
○ reservoirs are the male urethra and female vagina.
○ Feeds on bacteria in the vagina. -> causes vaginal pH to INC(alters naturally low pH environment).
○ Treated w/ metronidazole.
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