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
Gram-negative bacilli (8 examples)
* *E. coli*
* *Klebsiella*
* *Salmonella*
* *Vibrio cholerae*
* *Shigella*
* *Campylobacter jejuni*
* *Helicobacter pylori*
* *Bordatella pertussis*
* *Pseudomonas aeruginosa*
26
*E. coli*
* gram-negative bacilli
* mobile
* mode of transmission:
* fecal-oral route
* causes infections such as:
* 5 major GI infections
* 1. enteropathogenic
* 2. enterotoxigenic: \*\*most common cause of travelers diarrhea\*\* **Heat Labile Toxin**: 2nd messenger cAMP →loss of electrolytes and water →secretory diarrhea
* **Heat Stable Toxin**
* 3. enteroinvasive
* 4. enterohemorrhagic: **shiga toxin**: inhibits protein synthesis (leads to apoptosis)
* 5. enteroaggregative
* tx: avoid abx for enterohemorrhagic E.coli in children → increase risk of hemolytic uremic syndrome
* avoid anti-motility drugs
* rehydration
27
*Klebsiella*
* 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
*Salmonella*
* 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
*Vibrio*
* 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
Lipopolysaccharide (LPS)
* 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
31
Mycobacterium
* only bacteria that are acid-fast
* resist staining in lab
* rods
* *Mycobacterium tuberculosis*
* *Mycobaterium leprae*
32
*Mycobacterium tuberculosis*
* 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
*Mycobacterium leprae*
* 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
*Rickettsiae*
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
Measles
aka morbillivirus
negative sense, ssRNA
morbilliform rash
Koplik spots
begins on face and spreads to rest of body
36
Mumps
aka paramyxovirus
ssRNA
37
rubella
* toRch
* ssRNA
* 2-3 week incubation period
* lymphadenopathy
* pink maculopapular rash that begins on the face and **lasts 3 days**
* starts on face and spreads, spreads much f**aster than measles (rubeola)**
* **no cough, milder rash, and no koplik spots**
* tx: supportive care
38
Erythema Infectiosum
ssDNA
aka slap cheek, or Fifth disease
aka **Erythema infectiosum**
**rash worsens with bath**
caused by **Parvovirus B19**
targets the erythroblasts →stops RBC production
can cause neonatal hydrops faecalis
tx: intrauterine blood transfusion for hydrops faecalis
39
Rabies
Rhabdoviridae
bullet shaped ssRNA, negative sense
tx: rapid PEP
40
HPV
Human papilloma virus
dsDNA
41
Influenza
ssRNA
hemagluttinin and neuraminidase
tx: neuraminidase inhibitors
vaccines: target hemagluttinin
Type A = most common
Type B= humans only
Type C = nonsymptomatic, little medical concern
SHIFT vs DRIFT
42
Prion
Creutzfeldt-Jakob Disease
Sponge-like lesions in the brain
as prions build up in brain--\> it starts to shrink
pt usually dies within a year
43
Taniea Solium
from pigs helminth: tape worm
can cause cysticerosis if you ingest the eggs
tx: Praziquantel
44
Taenia Saginata
Cestodes (tapeworms)
from cows
sxs: weight loss, vomiting, appendicitis
do NOT form cysticercosis
tx: **Praziquantel**
45
Strongyloides stercoralis
Strongyloides stercoralis
nematode (round worm)
worm penetrates skin→lungs→GI tract
Loeffler's syndrome: eosinophilic pneumonia, cough up worm and swallow it
CAN HAVE AUTOINFECTION → poop out worms but they repentrate skin around the anus and autoinfect
Tx: Ivermectin or **albendazole**
45
Schistosomiasis
helminth: blood fluke (trematode)
* S. mansoni and S. japanicum: S Am, Mid East, Carib, Africa; Asia
* found in mesenteric venules, shed eggs into intestine
* hepatosplenomegaly, GI hemorrhage, portal hypertension
* S. haematobium: Africa and MidEast
* found in bladder veins, shed eggs into bladder/urine
* urticaria, hematuria, dysurea
* bladder cancer in advanced stages
* Diagnosis:
* **ID of eggs in stool or urine** (must be present in at least 3 samples)
* tissue biopsy (rectal or bladder)
* Tx: **Praziquantel**
46
Loeffler's Syndrome
eosinophilic, cough up worm and swallow it
47
Pinworms
* Enterobious vermicularis
* Helminth: nematode (round worm)
* tx: **Albendazole**
**\*\*most common helminth infection in US\*\* esp in children \<12 yo**
48
Roseola
HHV- 6
dsDNA
\*\*ONLY VIRAL EXANTHEM THAT BEGINS ON THE TRUNK\*\*
HIGH fever → rash
tx: supportive
49
Positive sense vs negative sense RNA
positive sense: very similar to mRNA → directly to protein
negative sense: is the complement to mRNA, needs to get converted to positive sense by RNA pol before translation can occur
50
Giardia
Giardia lamblia
* \*\*most common protozoan parasite in the US \*\*
* tx: metronidazole
51
Scabies
Sarcoptes scabiei
type of mite
tx. **Permethrin**
52
Candidiasis
yeast→Candida
* tx: **fluconazole**
* I**ntertriginous infections:** well-demarcated erythematous patches of varying size and shape, primary patches may have **satellite** papules and pustules
53
Histoplasmosis
* Histoplasma
* S**ystemic fungi and mold → yeast at 37C**
* inhalation from bats/ birds: CAVES and TREE REMOVAL
* acute pneumonia sometimes developes
* infect Macrophages
* bone marrow disruption
* apical pulmonary lesions resembling cavitary TB
* tx: **itraconazole**
54
Cryptococcosis
* **yeast** that can end up in the brain but is inhaled!
* \*\***Defining opportunistic infection in aids patients**\*\*
* skin lesions that look similar to acne, molloscum contagiosum, or basal cell carcinoma
* CNS: low grade fever, ocular or facial palseys, headache
* Lungs: pneumonia, AIDS (severe dyspnea)
tx: **Fluconazole for non CNS, CNS: amphotericin B**
55
Pneumocystis
* yeast: pneumocystis jirovecii
* \*\*only issue for immunocompromised people\*\*
* aerosolized: fever, dyspnea and DRY cough
tx: **Bactrim (sulfamethoxazole/trimethoprim )**
high risk for HIV pts with CD4 counts \<200/mcL
56
Strep pneumoniae
* gram + diplococci, ENCAPSULATED
* causes pneumonia:
* rusty mucus
* productive cough
* fever
* malaise
* sudden onset chills and rigors (violent shaking)
* causes: bacteremia and meningitis
* tx: **Ceftriaxone**
57
Neisseria meningitidis
* gram - diplococci, encapsulated
* tx: **3rd generation cephalosporins**
* prevention**: menveo and bexsero**
58
Neisseria gonorrhea
* gram negative diplococci
* fimbriae
* encapsulated
* tx: **Ceftriaxone**
59
Diptheria
* caused by Corynebacterium diptheria
gram + rod
* exotoxin
* begins with sore throat and fever
* pseudomembrane and lymphadenopathy
* myocarditis
* tx: **Diptheria antitoxin + erythromycin or penicillin**
60
Shigella
* gram - rod, with mobile tail
* bacterial dysentery
* facutative anaerobe
* fecal-oral
* fever, neutrophils in stool and blood may be present
* explosive watery diarrhea that progresses to mucoid and bloody with **pus in stool**
* produces "Shiga" enterotoxin: neurotoxic, cytotoxic, and enterotoxic
* associated with **seizures**
* tx: **oral rehydration and electrolyte replacement** and **fluoroquinolones**
*
61
Salmonellosis
* gram negative rod
* facultative anaerobe
* uncooked chicken and contact with reptiles
* S. typhi = typhoid fever
* enteric fever as a results of bacteremia
* "pea soup" diarrhea that may be bloody
* S. enterica
* gastroenteritis with **"pea soup" brown-green color**
* may have blood
* tx: **electrolyte and fluid replacement + Fluoroquinolones**
62
Campylobacter jejuni
* curved gram negative bacillus
* fever with periumbilical abdominal pain (can mimic acute appenditicis)
* diarrhea watery →bloody
* transmission: contaminated food, domestic animals are a reservoir
* associated with **Guillain Barre Syndrome**
* unpasteurized milk
* tx: **Macrolides or fluoroquinolones**
* **invasive diarrhea**
63
Non-invasive Diarrheas
* Pathophys: enterotoxins increase GI secretion of electrolytes→**secretory diarrhea**
* no cell destruction/mucosal invastion
* Affected Area: **small bowel→large voluminous** stool
* Vomiting: often predominant sxs
* fecal blood/wbc/mucus: absent
* examples: viral, S. aureus, V, cholera, entero**_toxigenic_** e. coli
64
Invasive Diarrheas
* Pathophys: **cytotoxins cause mucosal invasion and cell damage**
* affected area: **Large bowel** → many small-volume stools, high fever
* vomiting not as common
* + for fecal blood/ WBCs and mucus
* examples: enterohemorrhagic E coli, Shigella, Salmonella, Campylobacter, Yersinia
65
Metronidazole
antifungal and antiprotozoal
66
Botulism
* Gram positive rod, Spore former, exotoxin, obligate anaerobe
* neurotoxin blocks release of acetylcholine
* canned food, honey for \<1 year olds
* flaccid descending paralysis, N/V/D, 8 Ds, bilateral cranial nerve paralysis
* tx: antitoxin
67
Cholera
* Vibrio cholera, gram negative rod that looks like a comma, oxidase positive
* enterotoxin
* rice water stools
* NO fever
* diagnosis: stool cx
* tx: oral rehydration for mild cases, **doxycycline** for mod-severe cases
68
Rheumatic Fever
* causal agent: strep pyogenes (group A strep), gram positive cocci, beta-hemolysis, encapsulated
* Fever
* polyarthritis, carditis, **erythema marginatum** mostly on trunk and extremities → secondary autoimmune response
* tx: **Penicillin G/amoxicillin** and **aspirin**
69
Tetanus
* Clostridium tetani: gram positive rod, spore former, motile, obligate anaerobe, neurotoxins (exotoxin)
* spores from soil enter wound
* neurotoxins block release of inhibitory neurotransmitters like GABA and glycine → Severe Muscle Spasm descending
* tx: **Metronidazole with tetanus immune globulin**
* dtap and tdap
70
Malaria
* Plasmodium: blood and tissue protozoa. P. falciparum = most deadly: Cerebral malaria (AMS, delirium, seizures, coma) and blackwater fever (severe hemolysis +hemoglobinuria (dark urine) + renal failure)
* Cyclical Fevers (every 3 days or so)
* rigors, vomiting, myalgia, diaphoresis, hemolytic anemia, splenomegaly
* tx: **Chloroquine**
71
Toxoplasmosis
* protozoan carried by cats after ingesting infected mice
* disease in neonates is severe:
Tetrad of abnormalities:
- bilateral retinochoroiditis
- cerebral calcification
- hydrocephalus or microcephaly
- psychomotor retardation
* fever, jaundice, intracranial calcifications
* **diagnosis:** immunofluorescence assay for IgM antibody
* tx: **Pyremethamine**
72
Epstein Barr Virus
* dsDNA, mononucleosis, and Burkitt Lymphoma
* splenomegaly
* Burkitt Lymphoma: B-cell lymphoma presenting as jaw tumors in Africa
* tx: **Acyclovir** for mono, **Chemo** for burkitt lymphoma
73
ABx that target cell wall synthesis
* **Beta-lactams**
* penicillins
* cephalosporins
* carbapenems
* monobactams
* **Vancomycin**
* **Bacitracin**
74
Abx that target the Cell membrane
* Polymyxins
75
Abx that target the 30S subunit of prokaryotes
* target protein synthesis in prokaryotes
* tetracyclines
* aminoglycosides
76
abx that target folate synthesis
* sulfonamides
* trimethoprim
* aka targets nucleid acid synthesis in prokaryotes
77
abx that target DNA Gyrase
* aka abx that target nucleid acid synthesis in prokaryotes
* Quinolones
78
Abx that target RNA polymerase
* Rifampin
* aka abx that target nucleic acid synthesis
79
abx that target 50S subunit
* target protein synthesis in prokaryotes
* Macrolides
* clindamycin
* linezolid
* Chloramphenicol
* strepogramins
80
-azoles
* antifungals that inhibit the synethsis of ergosterol (the main fungal sterol)
81
-polyenes
82
5- fluorocytosine
* antifungal that inhibits macromolecular synthesis
* inhibits fungal nucleid acid synthesis
83
Classes of Antivirals
* Antiretrovirals:
* attachment and penetration
* uncoating
* reverse transcription
* Integration
* Transcription
* Translation
* Release
* Antivirals
* attachement and penetration
* uncoating
* replication and expression
* assembly
* release
84
antifungals that form membrane pores
* amphotericin B
* nystatin
85
Gram Positive Bacilli (5 examples)
* *Bacillus anthracis*
* *Corynebacteria diptheria*
* *Clostridium tetani*
* *Clostridium botulinum*
* *Clostridium difficile*
86
Yeast vs Mold Reproduction
* yeast reproduction:
* budding asexually though mitotic asexual divison
* Mold reproduction:
* form hyphal septa
87
zika
* ssRNA, negative sense
* causes microcephaly, often asymptomatic in adults
* can be sexually transmitted and through **aedes** mosquito
* s/sxs: maculopapular rash, joint pain, fever, conjunctivits
* diagnosis: RT-PCR testing
* tx: rest, acetaminophen → avoid NSAIDs and ASA
