4/19 gram negative
Terms
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- give two ex of gram neg cocci
- Neisseria gonorrhoeae. Neisseria meningitidis.
- what is the second most common cause of meningitis
- Neisseria meningitidis
- what is unique about S.typhi compared to the other strains of Salmonella
- strict human pathogen. causes typhoid fever
- what are clinical manifestations and virulence factors for salmonella typhi
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Clinical manifestations
Enteric fever
Increasing fever, headache, myalgias, malaise, anorexia= 1 week
Then GI tract symptoms
Typhoid fever- rose spots on abdomen
Virulence factors
Invade
Go through cells to submucosa
Macrophages engulf
Survive in macrophages and are taken to liver, spleen and bone marrow
Endotoxin
Vi capsule- Salmonella typhi infections - Most important human pathogens in Haemophilus sp
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H. influenzae
H. ducreyi - Haemophilus influenzae. transmission. virulence factors.
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Organisms transmitted person-to-person through respiratory secretions
Virulence factors
Capsule
antiphagocytic
Endotoxin
Stimulates inflammation
Pili
Allows adherence to epithelial cells - what is the gram-negative coccobacillus that causes whooping cough?
- Bordetella pertussis
- Bordetella pertussis. transmission. symptoms. virulence factors.
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Human pathogen- no animal or environmental reservior
Spread person to person through infectious aerosols
Begins with cold-like symptoms
Toxins released by bacteria cause death of ciliated epithelial cells
Leads to paroxysms of coughing, lasting for weeks
Individuals with waning immunity can be carriers, can have persistent, non-paroxysmal cough
produces several adhesins: Filamentous hemagglutinin (adhere galactose residues of the glycolipids on the membrane of ciliated epithelial cells of the respiratory tract), pertussis toxin, and pertactin - Legionella sp. transmission. CM. virulence factors.
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Transmission/epidemiology
Aquatic saprophytes
Grow in amoebae in the water
Survive high temperatures and treatment with chlorine
Most infections occur in late summer and early fall
Infections follow exposure to environmental source
Clinical manifestations
Usually infections are seen in elderly and in those with compromised pulmonary function.
Legionnaire’s disease- pneumonia
Virulence factors- survive in alveolar macrophages and monocytes; endotoxin - Pseudomonas aeruginosa. transmission. CM. virulence factors.
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Transmission/epidemiology
Found everywhere- soil, water, food and on plants.
Survives many disinfectants
Transmission to humans comes from some environmental source
Usually involves an invasive device (Foley catheter) or destruction of an important protective structure (skin).
Clinical manifestations- usually in compromised patients
Outer ear infections- Swimmer’s ear and malignant otitis media (diabetics)
Folliculitis- hot tub use
Pneumonia- cystic fibrosis patients
Wound infections- burn patients
UTI- associated with Foley catheter
Keratitis- contact wearers
Virulence factors
Adhesins
Capsule
Endotoxin
Pyocyanin
Exotoxin A and S
Elastase - Neisseria gonorrhoeae. transmission. CM men vs women. local vs disseminated.
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Transmission/epidemiology
Sexually transmitted infection
To neonates during delivery
Clinical manifestations
Men- urethritis, proctitis, pharyngitis
Women- cervicitis, urethritis, proctitis, pharyngitis
Disseminated infections
Women- PID, septicemia, skin and joint manifestations, septic arthritis
Men- septicemia, skin and joint manifestations, septic arthritis
Note most common cause of septic arthritis in sexually active young adults. - Virulence Factors of Neisseria gonorrhoeae
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Lacks capsule, although cell surface repels phagocytes
Pilin
Pili that facilitate attachment to epithelial cells
Opa proteins
Mediate strong adherence to epithelial cells; gives N. gonorrheae colonies an opaque appearance
Por protein (Porin)
Pore in cell membrane for uptake of nutrients
Aids bacterial invasion into epithelial cells
Iron acquisition proteins (several)
Lipooligosaccharide
endotoxin-like activity
IgA protease - list 5 Enteric Gram-Negative Rods groups?
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Enterobacteriaceae
Vibrio
Campylobacter
Helicobacter
Bacteroides - covered in lecture on anaerobes - Common Virulence Factors of Enterobacteriaceae
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Endotoxin
Capsule
Antigenic variation
Iron acquisition proteins
Resistance to complement
Antibiotic resistance - Salmonella enterica. virulence factors. transmission.
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Found in GI tract of birds and reptiles Transmission/epidemiology
Consumption of contaminated foods
Handling pets
Fecal-oral transmission
Need large number for infection (106-108)
Virulence factors
Attachment
fimbriae
Intracellular invasion- Type III secretory systems
Secrete bacterial virulence factors into cells following attachment
Intracellular survival
Endotoxin - which bacteria Do not ferment lactose; no H2S gas; nonmotile.
- Shigella sp
- Which Shigella sp. is most common in U.S. (particularly in daycare centers)?
- S. sonnei
- CM of Shigella sp.
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Clinical manifestations
Fever, abdominal cramps, blood- and mucus-containing stools.
Starts as diarrhea that then becomes dysentery (bloody) - transmission and CM of Yersinia enterocolitica
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Transmission
Ingestion of contaminated food, milk or water
Able to grow at cold temperatures
Farm animals (especially pigs) are normal reservior
Clinical manifestations
Diarrhea, fever, abdominal pain
1-2 weeks duration
Chronic form can persist for months
Reactive arthritis (discussed in lecture on infectious causes of arthritis) - Vibrio cholera virulence factors.
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Virulence factor
Cholera toxin increases cAMP levels.
Ions go out of cell, water follows. - Campylobacter sp most common in US?
- Bacterial gastroenteritis- C. jejuni most common cause of this disease. Most common in U.S.= C. jejuni