Gram Negative Bacteria Flashcards
(48 cards)
What are three kinds of lactose negative enterics?
salmonella, shigella, yersinia
What kind of stain is used for mycobacteria (acid-fast staining)?
carbol fuschin (Ziehl-Neilson)
Are mycobacteria anaerobic?
No, aerobic
Isoniazid, rifampin, pyrazinamide and ethambutol are used to treat ____________
TB
The cytotoxin involved in M. tuberculosis is ….
cord factor (serpentine growth)
Does M. tuberculosis release exo/endo toxins? What are the virulence factors for TB?
No endo/exotoxins, but a cytotoxin (cord factor)
wax D and PPD are virulence factors
Are antibodies important for tb? Where does the TB live?
No, there is no humoral immunity for TB, but cell/ cell-mediated immunity is present. T lymphocytes and cytokines protect against TB. TB lives inside of MACROPHAGES
What is the importance of a granuloma to TB infection? TNF?
Granuloma is aggregation of monocytes and macrophages, important for controlling tb infection in the lung, in tb there is no granuloma infection. So without granuloma the bacteria can spread from lungs to other parts of the body
Tnf- tumor necrosis factor alpha- important for inducing granuloma formation
Describe the pathogenesis of TB
TB enters macrophages, they aggregate and die, creating a caseous center n the tubercle surrounded by macrophages and lymphocytes –>dormant
In disease state, the tubercle ruptures after liquefication and the bacilli spill into the bronchiole and is released to the respiratory system
Why can the M. Tuberculosis be dormant?
Restriction in growth granuloma turns into caseum, low ph, low oxygen so bacteria in dormant phase because unfavorable conditions for growth of tb
In luciferin-luciferase reaction, positive light production means….
bacteria is resistant to antibiotics
Why is streptomycin limited in its action against TB?
It is only active against the etracellular bacilli, and there are strains of bacteria resistant to it
Med that inhibits RNA synthesis for TB
Rifampin
Anti-TB drug that penetrates extra/intracellular environments of lesions and deters selection of resistant mutants
Ethambutol
Bactericidal against organisms in acidic environment of phagosomes
Pyrazinamide
What group of atypical mycobacteria produce yellow-orange pigment in PRESENCE of light and includes M. kansasii and M. marinum? fish tank –>skin infections
Group 1
What group of atypical mycobacteria produce yellow-orange pigment in ABSENCE of light and includes M. scrofulaceum? (in soil and water, leads to removal of lymph nodes)
Group II
What group of atypical mycobacteria produce little or no pigment and includes M. avium-intracellulare, (causes pulmonary infection)
Group III
What is unique about growing M. leprae?
can’t grow on artificial medium and doesn’t grow well above 30 degrees C. It is an obligate intracellular parasite, so needs to be grown in armadillo or mouse
What is the main difference between tuberculoid and lepromatous leprosy?
Immune response is in place and robust for tuberculoid, while there is a low immune response in lepromatous)
Where are nocardia found, and how do they affect the body?
Found in the soil, are opportunistic pathogens causing pneumonia with abesses and necrosis
What bacteria is characterized by:
o Watery diarrhea, mostly in infants and developing countries
o Bundle forming pili attach bacteria to host sell, Type 3 secretion system injects effector proteins into host cell and releases factors for ‘intimate attachment’, making actin pedestals and damage of microvilli. This means there will be bad reabsorption, causing watery diarrhea
o Virulence factor- bundle forming pili, type 3 secretion
EPEC (enteropathogenic e. coli)
What bacteria is characterized by:
o Cause of traveler’s diarrhea, transmission via food and water contaminated with human waste/ direct contact
o ETEC colonize the small intestine, cause prolonged hypersecretion of Cl- ions and water by intestinal mucosal cells, while inhibiting the reabsorption of sodium. Gut becomes full of liquid, making watery diarrhea.
o Not common in US, therapy is fluid replacement, disease is self-limiting
o Toxins: heat stable (ST) causes elevation in cGMP, heat labile (LT) causes elevated cAMP
ETEC (enterotoxigenic e. coli)
What bacteria is characterized by:
o Found in USA, usually O157:H7, humans eat undercooked meat, fluids are not reabsorbed in intestinal tract
o Only need about 100 cells to cause an infection
o Bloody diarrhea/dysentery, no fever (afebrile), self-limiting, few leukocytes
o Associated with HUS=hemolytic uremic syndrome, which is acute renal failure in children 5-10
EHEC- enterohemorrhagic e. coli
