Final Flashcards
Since 60% of pneumonia is caused by S. pnuemoniae, what are the other bacteria that cause it?
Chlamydophila (Chlamydia) pneumoniae Mycoplasma pneumoniae Haemophilus influenzae Pneumocystis carinii
What are some symptoms of pneumonia and whats its incubation period?
abrupt onset fever, chills chest pain difficulty in breathing productive cough rust coloured sputum incubation: 1 - 3 days
How do you treat pneumonia?
penicillin G erythromycin (azithromycin, clarithromycin) ceftriaxone vancomycin (usually only for HAP)
What happens during stage 1 of pneumonia?
bacteria stimulate flow of fluid into alveoli fluid promotes growth of the bacteria fluid allows spread of bacteria to other alveoli and lobes loss of air exchange capacity due to fluid
What happens during stage 2 and 3 of pneumonia?
second stage (early consolidation) infiltration of the alveoli by neutrophils and red blood cells phagocytosis of bacteria the point where infection brought under control third stage (late consolidation) alveoli are packed full of neutrophils with ingested bacteria clearance of bacteria from the lungs occurs “hepatization” of lungs, alveoli look like hepatocytes
Describe stage 4 and what is special about pneumonia?
neutrophils leave macrophage clean up debris Pneumonia lack of permanent damage very little fibrous scar tissue
What bacteria causes epiglotittis?
epiglottitis is nearly always caused by H. influenzae B
Give me some characteristics for Mycoplasma pneumoniae?
the mycoplasma are the smallest free-living bacteria they do not produce peptidoglycan not sensitive to b-lactams and vancomycin membranes contain sterols can take up to 3 weeks to grow colonies
What must the mdeia contain in order to grow M. pnuemoniae?
isolation media contain peptone enriched with yeast extract and serum to provide cholesterol also b-lactam antibiotics to suppress other bacterial contaminants methylene blue can be added to suppress all other Mycoplasma species and/or glucose as M. pneumoniae is the only species which ferments glucose to acid
Give me some characteristics of Klebsiella pnuemoniae.
Gram-negative bacillus, lactose positive with gas production MR-VP (- +) Indole negative, citrate positive (E. coli is MR-VP + - and indole +, citrate -)
What are some characteristics of the Influenza virus?
member of the Orthomyxoviridae a single-stranded, negative sense RNA virus with a segmented genome enveloped virus (host cell membrane) the surface of the virus is covered with spikes called peplomers there are two types of spikes, one is the hemagglutinin and the other is the neuraminidase
In the influenza virus, how many genomes are produced and what are the proteins produced as a result?
8 RNA segments each codes for one or more proteins, 10 in total HA – hemagglutinin and NA – neuraminidase Matrix protein-1, M-2 Nucleoprotein Polymerase B1, B2 and A Non-structural-1 and NS-2
How does the influenza virus escape the host cell?
HA binds the virus to its receptor sialic acid tipped galactose carbohydrates NA cleaves sialic acid from the end of the receptor to allow the newly formed virus to escape
Where are the matrix proteins found in the influenza virus and which is the most important?
M1 coats the inside of the envelope M1 is the most important protein for the structure, assembly and budding of the virus M2 is found in small amounts in the envelope
What are the symptoms of influenza virus and how is it transmitted?
fever/chills headache, muscle aches and pains malaise cough lasting 3 - 7 days Through water droplets spread by coughing and sneezing
How does the influenza virus enter the cell?
the influenza hemagglutinin binds to sialic acid containing glycolipid/glycoprotein receptor on epithelial cells viral particles are taken up by receptor-mediated endocytosis and fuse with a lysosome the drop in pH in the virus containing endosome causes a conformational change in hemagglutinin. Part of the hemagglutinin is now exposed and can mediate fusion between the viral envelope and the endosome membrane nucleocapsids are then liberated into cytoplasm and move to the nucleus
How does the Influenza virus replicate in the host cell?
viral RNA is replicated in cell nucleus using viral encoded RNA-dependent RNA polymerase 10 transcripts produced (+ sense mRNA) viral mRNAs “steal” the 5’ cap and 3’ polyA tail from preformed cellular mRNAs viral proteins are synthesised nuclear replication of the original 8 (-) strand RNAs
What is the causative agent of Typhoid?
Salmonella Typhi (
The fatality rate of Typhoid is ____
10%
How is Typhoid spread?
Usually food or water borne, but mostly food borne in developed countries
What organisms cause symptoms extremely similar to Typhoid?
Salmonella Paratyphi A, B, C and S. Typhimurium
S. Typhi and S. Typhimurium share ___% of their genes. How do they differ? Why is this relationship interesting?
89%. S. Typhi affects only humans whereas S. Typhimurium affects lots of mammals and even reptiles. S. Typhi evolved relatively recently and has a large amount of genes that are “turned off”, probably resulting in the limited host range.
What is it called when one of two closely related organisms has genes that are inactive, causing the differences between the two
Reductive evolution
What countries are hot spots for Typhoid?
South east asia is main hotspot, then rest of Asia, Africa,and South America
What was the most important health advancement affecting Typhoid rates in North America? What were typhoid rates like before this?
Water treatment. introduction of filtration and chlorination reduced mortality by 50%, and infant mortality by 75%. Typhoid death rates in 1900-1920 varied from 20 - 100 per 100 000 per year. After treatment it fell to 2 per 100 000 per year.
Who gave us the idea of an asymptomatic carrier?
TYPHOID MARY!!! she worked in a restaurant and had some mad dank typhoid, which was aymptomatic but she was shedding cells like nobody’s business. Then she was basically locked up forever
Describe the advent of Typhoid in Winnipeg
Winnipeg was at one point named the Typhoid capital. The lack of sewers and the fact that drinking water was drawn straight from rivers or wells led quickly to the spread of Typhoid (duh, there are two rivers in the middle of the city and everyone is dumping their shit in them). So in the 1880s the city made all new properties use the new sewer system, but they didn’t force old properties to change, which was dumb. Then they started drinking more from wells (which are partially filtered, since aquifers are usually under sand). FINALLY, in 1904 sewer connections were made mandatory. They city made most outhouses illegal. Typhoid rates finally decreased
Describe the symptoms of typhoid fever
Fevers spike quickly reaching 40degrees over 2-3 days. Headaches, pain, lethargy, anorexia, abdominal pain and constipation are common. In the 2nd week as fever dies down a bit the bloody diarrhea appears. Can develop rosy spots on chest and abdomen.
What is the most common cause of death with Typhoid?
Perforated intestine or intestinal hemorrhaging
How is typhoid treated?
Used to be treated with toxic Chloramphenicol. Then we moved to ampicillin and contrimoxazole, which S. Typhi quickly became resistant to. Now we use a 3rd gen cephalosporin or a fluoroquinolone. If the strain is resistant to many antibiotic we use azithromycin
What types of typhoid vaccines exist?
An oral attenuated vaccine and a Vi (capsule) antigen vaccine
How is Typhoid diagnosed
Blood cultures, sometimes stool (can also look for neutrophils in stool) or rose spot culture, bone marrow culture (best and most inconvenient diagnostic tool). Cultures plated on a selective medium like Salmonella-Shigella
How does one determine if a bacterial species is in fact S. Typhi in a clinical lab setting?
Slide agglutination with anti-O antiserum.
S. Typhi and S. Typhimurium share ___% of their genes. How do they differ? Why is this relationship interesting?
89%. S. Typhi affects only humans whereas S. Typhimurium affects lots of mammals and even reptiles. S. Typhi evolved relatively recently and has a large amount of genes that are “turned off”, probably resulting in the limited host range. S. Typhimurium infections can also be killed by macrophage.
How does one determine if a bacterial species is in fact S. Typhi in a clinical lab setting?
Slide agglutination with anti-O antiserum.
How to the bacteria causing Typhoid infect you
Pass through intestinal epithelium through a process called “ruffling”, convincing microvilli to phagocytize themselves, forming a small vacuole around the bacterium. Can also enter by breaking the junctions of the columnar cells. Some escape into blood stream, other organs such as the liver. The bacteria live inside of macrophage, replicating until they burst forth and cause secondary bacteremia. The bacteria then REINFECT the intestine, necrotizing tissue and causing bloody diarrhea.
What other organs to S. Typhi bacteria like to infect
Gallbladder - Causes leakage of more bacteria into intestines
What can happen when the Gallbladder is infected during Typhoid?
Can become permanent. The person may be a permanent shedder and carrier of S. Typhi. Like Typhoid Mary
What other organs to S. Typhi bacteria like to infect
Gallbladder - Causes leakage of more bacteria into intestines Liver
How is Salmonella taxonomized? IT MAKES NO SENSE
Basically there are several (well, technically >2400) serovars, but there are 7 GENETIC variants (I, II, IIIa, IIIb, IV, V, VI). There are only two species but Salmonella enterica is divided into those 7 “subspecies”. The serovars are determined based on antigens (somatic, flagella, capsular). These help us identify paratyphi, typhimurium and typhi).
Which of the lymphocytes produce antibodies and which produce cytokines?
B = antibodies T = Cytokines
Since both B and T cells produce memory cells, what is the resulting lifespan?
20 years
How do antibodies affect bacteria?
They specifically and non-covalently bind to antigens. This binding prevent attachment of the pathogens, neutralizes toxins, opsonization, and serves as a signal to the immune system.
