Microbio Ch. 20 Notes PDF

Gram negative bacteria: due in part to lipid A in the bacterial cell wall - disseminated intravascular coagulation (blood clots throughout blood vessels) Potential e shock Neisseria: N. gonorrhoeae and N. meningitidis Neisseria gonorrhoeae: only occurs in humans (no animal reservoir)...

Gram negative bacteria: due in part to lipid A in the bacterial cell wall - disseminated intravascular coagulation (blood clots throughout blood vessels) Potential e shock Neisseria: N. gonorrhoeae and N. meningitidis Neisseria gonorrhoeae: only occurs in humans (no animal reservoir) - gonococci adhere to the genital, urinary, and digestive tract - gonococci can evade the immune system (survive within neutrophils) - ophthalmia neonatorum: infant blindness due to a gonorrheal infection of the eyes - Gonorrhea in med: inflammation causes painful urination and pus-filled discharge - gonorrhea in women: causes sterility - infection of the cornea or respiratory tract of newborns can occur during childbirth - diagnosis: asymptomatic; gram-negative diplococci in pus from inflamed penis - treatment: complicated due to resistant strains - prevention: eye infections in newborns prevented with antimicrobials (Silver nitrate until 1980s) Neisseria meningitidis: most common cause of meningitis in individuals under 20 years old - can be normal microbiota of the upper respiratory tract - transmitted by respiratory droplets among people living in close contact (dorms, barracks) - can cause death within 6 hours of symptoms - vaccination protects against serogroups A, C, Y, and W but not B due to similarities with neurons - treatment: intravenous penicillin - asymptomatic carriers make eradication unlikely Two families contain most human pathogens:  - Enterobacteriaceae (oxidase -) - pasteurellaceae (oxidase +) Enterobacteriaceae: ubiquitous - enteric bacteria are the most common gram-negative pathogens of humans, mostly opportunistic - nitrate to nitrite and ferment glucose - aerobic - O polysaccharide on surface, H antigen on flagella; antigens used for identification (E. coli O157:H7) - diagnosis: enteric bacteria in urine, blood, and cerebrospinal fluid; biochemical tests rapidly identify enteric bacteria - coliforms (rapidly ferment lactose, normal microbiota but may be opportunistic pathogens), noncoliform opportunists (do not ferment lactose), true pathogens Coliform Opportunistic Enterobacteriaceae -coliforms (indicator organisms) - coliforms in water indicate impure water and poor sewage treatment - O-somatic, H-flagella, K-capsule antigens - gastroenteritis is the most common disease - E. coli O157:H7 - most prevalent pathogenic E. coli - Shiga-like toxin Truly Pathogenic Enterobacteriaceae - Salmonella, Shigella, and Yersinia - almost always pathogenic due to numerous virulence factors - most human infections due to consuming food contaminated with animal feces - poultry and eggs - typhoid fever (human feces)  - Salmonella: Typhoid fever (humans are the only host) - gallbladder may be removed from carriers to prevent infection of others - vaccines provide temporary protection to travelers - shigella: S. dysenteriae, S. flexneri, S. boydii, S. sonnei - severe form of dysentery (pus and bloody stool), associated poor hygiene and sewage treatment - Shigellosis is typically self-limiting - Yersinia: bubonic plague (50% death untreated), pneumonic plague (near 100% fatality) The Pasteurellaceae - Pasteurella, Haemophilus (small, nonmotile, facultative anaerobes) - Haemophilus influenzae: common cause of meningitis prior to vaccination (3-28 months old) Bordetella: - causes pertussis (whooping cough) - paroxysmal stage, violent coughing, gasping for air as patient tries to cough up mucus that was trapped by cilia. Coughing so hard can break ribs - bacteria inhaled in aerosols multiply in ciliated cells Pseudomonads - aerobic bacilli - ubiquitous in soil, decaying organic matter, and moist environments Pseudomonas aeruginosa - opportunistic infections in immunocompromised patients (can colonize almost any organ or system, burn victims) - biofilm protects bacteria from phagocytosis Prevotella: associated with a healthy diet high in plants