Module 12: Microbiology and Infection Flashcards
1
Q
The process of infection
A
- agent
- reservoir
- portals of entry and exit
- mode of transmission
- immunity
Robert Koch and Koch’s postulates
2
Q
Definition and Types of Reservoirs
A
- Definition: the normal habit where the agent lives and multiplies
- where the agent propagates itself in nature
- Types:
- symptomatic carriers
- carriers
- inapparent throughout history
- incubatory
- convalescent
- animals
- direct zoonoses
- inanimate objects
- water
- food
- soil
- air
- fomites
3
Q
The Portals of Infection
A
- 3 I’s: inhalation, ingestion, injection
- respiratory tract
- upper and lower
- **most common**
- conjuctiva
- urogenital tract
- GI tract
- upper and lower
- placenta
- mother to child transmission
- skin
- broken and unbroken
4
Q
Modes of Transmission
A
- contact
- requiring proximity to an infected host or discharge from an infected host
- vehicle:
- an inanimate intermediate carrier
- i.e. chapstick, shared waterbottle
- Vector
- an animate carrier, often an insect
- mechanical
- e.g. carried on the foot of an insect
- biological:
- grows inside vector
- i.e. mosquito
- grows inside vector
5
Q
Define: Infection
A
- entry and multiplication of a microorganism or parasite in the body of a host
6
Q
Define: Infectious disease
A
infection + signs and symptoms
7
Q
Define: Contamination
A
Presence of a living agent on the exterior of the body or an article of clothing
8
Q
Define: Reservoir
A
the normal habitat where the agent lives and multiplies
- a dead-end host or temporary resting place of the agent is not a reservoir
9
Q
Define: Carrier
A
a person or animal that harbor an infectious agent yet does not show any signs of infection
10
Q
Define: Zoonosis
A
an infection naturally transmitted between non-human animals and humans
11
Q
Define: Immunity
A
the host factors that alter the likelihood of infection and disease after the agent is encountered
12
Q
Overview: Prokaryotes
A
- Bacteria
- do NOT have a true nucleus
- do NOT have organelles
- smaller ribosomes (70S) (30S/ 50S)
13
Q
Overview: Eukaryotes
A
- Fungi; Protoza and Helminths
- have a true nucleus
- have organelles
- larger ribosome (80S) (40S/60S)
14
Q
4 major groups of pathgoens that infect humans
A
- bacteria = prokaryotes
- fungi = eukaryote
- protozoa and helminths = eukaryotes
- viruses
15
Q
Gram Positive Bacteria
A
- stain Purple due to iodine
- contain thick Peptidoglycan cell wall
16
Q
Gram Negative Bacteria
A
- stain orange
- contain lipopolysaccharide outer membrane
17
Q
Catalase Test
A
- will demonstrate if a bacteria is capable of aerobic respiration
- catalase is an enzyme that is used to protect the cell from oxidative damage by reactive oxygen species
- 2H2O2 → 2H2O + O2
- enzyme action is to breakdown toxic H2O2 (substrate name) producing gaseous oxygen and water
18
Q
Coagulase Test
A
- this test is used to identify S.aureus which produces the enzyme coagulase
- Coagulase causes plasma to clot by converting fibrinogen to fibrin
- two types of coagulase are produced by most S. aureus
- Free coagulase:
- converts fibrinogen to fibrin by activating a coagulase-reacting factor present in plasma
- free coagulase is detected by clotting in the test tube
- converts fibrinogen to fibrin by activating a coagulase-reacting factor present in plasma
- Bound coagulase: (clumping factor)
- converts fibrinogen directly to fibrin without coagulase-reacting factor
- this can be detected by the clumping of pf bacterial cells in the rapid slide test
- converts fibrinogen directly to fibrin without coagulase-reacting factor
- Free coagulase:
19
Q
Gram-Positive Cocci (3 examples)
A
- Staphylococcus aureus
- Streptococcus pneumoniae
- Streptococcus pyogenes (GAS)
20
Q
Staphylococcus aureus
A
- Gram-positive cocci
- non-motile, catalase positive, oxidase negative
- mode of transmission:
- contact, unwashed hands
- Causes infection including:
- skin abscesses, osteomylitis, endocarditis, septic arthritis, entero toxis: Toxic shock syndrom and SSSS
- enterotoxins lead to effects in gut = diarrhea
- skin abscesses, osteomylitis, endocarditis, septic arthritis, entero toxis: Toxic shock syndrom and SSSS
- tx for MRSA: oral: Vancomycin or doxycyline, clindamycin, trimpethoprim-sulfamethoazole (Septra)
21
Q
Staphylococcus epidermidis
A
- Gram positive cocci
- mode of tranmission:
- contact, unwashed hands
- Causes infections such as:
- prosthetic device infections, IV catheter infections, sepsis, meningitits, endocarditis, UTI
22
Q
Gram-Negative Cocci (2 examples)
A
- Neisseria gonorrhoeae
- Neisseria meningiditis
23
Q
Neisseria gonorrhoeae
A
- gram-negative cocci
- mode of tranmission:
- sexually; newborns can be infected during burth
- Cause of infections:
- in genital tract
- can reach organs via the bloodstream
- ceftriaxone + azithromycin
24
Q
Neisseria meningiditis
A
- gram-negative diplococci
- catalase and oxidase positive
- non-motile
- encapsulated
- mode of transmission:
- airborne droplets
- Causes infections such as:
- meningococcemia, and meningitis
- most severe form of meningococcemia = Waterhouse Friderichsen syndrome
- **life-threatening**
- most severe form of meningococcemia = Waterhouse Friderichsen syndrome
- meningococcemia, and meningitis
- tx: 3rd generation cephalosporins (ceftriaxone)
25
Q
Gram-negative bacilli (8 examples)
A
- E. coli
- Klebsiella
- Salmonella
- Vibrio cholerae
- Shigella
- Campylobacter jejuni
- Helicobacter pylori
- Bordatella pertussis
- Pseudomonas aeruginosa
26
Q
E. coli
A
- gram-negative bacilli
- mobile
- mode of transmission:
- fecal-oral route
- causes infections such as:
- 5 major GI infections
- enteropathogenic
- enterotoxigenic: **most common cause of travelers diarrhea** Heat Labile Toxin: 2nd messenger cAMP →loss of electrolytes and water →secretory diarrhea
- Heat Stable Toxin
- enteroinvasive
- enterohemorrhagic: shiga toxin: inhibits protein synthesis (leads to apoptosis)
- enteroaggregative
- 5 major GI infections
- tx: avoid abx for enterohemorrhagic E.coli in children → increase risk of hemolytic uremic syndrome
- avoid anti-motility drugs
- rehydration
27
Q
Klebsiella
A
- gram-negative bacilli
- mode of transmission:
- contact with ulcerative genital lesions
- causes infections such as:
- lobar pneumonia, lung abscess, UTI, bacteremia, enteritis, and meningitis (in infants), wound infections
28
Q
Salmonella
A
- gram-negative bacilli
- uncooked chicken
- mode of transmission:
- fecal-oral
- specific contaminated food
- causes infections such as:
- “food poisoning” or gastroenteritis
- Starts with abdominal cramping followed by fever, diarrhea, and sometimes vomiting
- Diagnostic: Cx of stool
- Tx: Ceptra or Cipro or Fluoroquinolones (or 3rd generations cephalosporins if severe)
29
Q
Vibrio
A
- gram-negative bacilli
- mode of transmission:
- fecal-oral; raw or inadequately cooked seafood
- Causes infections such as:
- cholera pandemics, epidemics and worldwide outbreaks
- tx: Tetracycline for moderate-severe cases
30
Q
Lipopolysaccharide (LPS)
A
- produced by most gram-negative bacteria
- mostly serves at the major structural component of the outermembrane
- **modulates responses by the host immune system**
- low quantities →inflammation:
- monocyte/macrophage/ neutrophil activation
- endothelial activation
- complement activation
- Moderate quantities → systemic effects:
- fever
- leukocyte release from bones
- acute-phase reactants from liver
- High quantities → Septic Shock
- low cardiac output
- low peripheral resistance
- blood vessel ijjury, thrombosis, DIC
- ARDS
- acute respiratory distress syndrome
- low quantities →inflammation:
31
Q
Mycobacterium
A
- only bacteria that are acid-fast
- resist staining in lab
- rods
- Mycobacterium tuberculosis
- Mycobaterium leprae
32
Q
Mycobacterium tuberculosis
A
- acid-fast (lack a cell wall → only cholesterol), slow growing
- mode of transmission
- respiratory droplets
- 1.7 million people die each year
- causes disease in highly oxygenated tissues → aerobes
- infect the macrophages
- formation of granulations
33
Q
Mycobacterium leprae
A
- acid-fast
- rod
- mode of transmission:
- prolonged close contact
- humans are natural host
- Lesions end up on cooler parts of the body such as the skin, nose, and peripheral nerves
- aka Leprosy
34
Q
Rickettsiae
A
Rocky Mountain Fever
obligate intracellular gram negative coccobacilli
non-specific sxs (fever, myalgias, severe headache)
Rash that appears 2-6 days later
tx: Doxycycline
35
Q
Measles
A
aka morbillivirus
negative sense, ssRNA
morbilliform rash
Koplik spots
begins on face and spreads to rest of body
73
Q
ABx that target cell wall synthesis
A
-
Beta-lactams
- penicillins
- cephalosporins
- carbapenems
- monobactams
- Vancomycin
- Bacitracin
74
Q
Abx that target the Cell membrane
A
- Polymyxins
75
Q
Abx that target the 30S subunit of prokaryotes
A
- target protein synthesis in prokaryotes
- tetracyclines
- aminoglycosides
76
Q
abx that target folate synthesis
A
- sulfonamides
- trimethoprim
- aka targets nucleid acid synthesis in prokaryotes
77
Q
abx that target DNA Gyrase
A
- aka abx that target nucleid acid synthesis in prokaryotes
- Quinolones
78
Q
Abx that target RNA polymerase
A
- Rifampin
- aka abx that target nucleic acid synthesis
79
Q
abx that target 50S subunit
A
- target protein synthesis in prokaryotes
- Macrolides
- clindamycin
- linezolid
- Chloramphenicol
- strepogramins
80
Q
-azoles
A
- antifungals that inhibit the synethsis of ergosterol (the main fungal sterol)
83
Q
Classes of Antivirals
A
- Antiretrovirals:
- attachment and penetration
- uncoating
- reverse transcription
- Integration
- Transcription
- Translation
- Release
- Antivirals
- attachement and penetration
- uncoating
- replication and expression
- assembly
- release
