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NRS 250: Exam 2 ENT and ID > Module 12: Microbiology and Infection > Flashcards

Module 12: Microbiology and Infection Flashcards

1
Q

The process of infection

A
  1. agent
  2. reservoir
  3. portals of entry and exit
  4. mode of transmission
  5. immunity

Robert Koch and Koch’s postulates

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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
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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
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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
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5
Q

Define: Infection

A
  • entry and multiplication of a microorganism or parasite in the body of a host
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6
Q

Define: Infectious disease

A

infection + signs and symptoms

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7
Q

Define: Contamination

A

Presence of a living agent on the exterior of the body or an article of clothing

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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
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9
Q

Define: Carrier

A

a person or animal that harbor an infectious agent yet does not show any signs of infection

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10
Q

Define: Zoonosis

A

an infection naturally transmitted between non-human animals and humans

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11
Q

Define: Immunity

A

the host factors that alter the likelihood of infection and disease after the agent is encountered

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12
Q

Overview: Prokaryotes

A
  • Bacteria
  • do NOT have a true nucleus
  • do NOT have organelles
  • smaller ribosomes (70S) (30S/ 50S)
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13
Q

Overview: Eukaryotes

A
  • Fungi; Protoza and Helminths
  • have a true nucleus
  • have organelles
  • larger ribosome (80S) (40S/60S)
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14
Q

4 major groups of pathgoens that infect humans

A
  1. bacteria = prokaryotes
  2. fungi = eukaryote
  3. protozoa and helminths = eukaryotes
  4. viruses
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15
Q

Gram Positive Bacteria

A
  • stain Purple due to iodine
  • contain thick Peptidoglycan cell wall
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16
Q

Gram Negative Bacteria

A
  • stain orange
  • contain lipopolysaccharide outer membrane
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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
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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
    • 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
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19
Q

Gram-Positive Cocci (3 examples)

A
  • Staphylococcus aureus
  • ​Streptococcus pneumoniae
  • ​Streptococcus pyogenes (GAS)
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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
  • tx for MRSA: oral: Vancomycin or doxycyline, clindamycin, trimpethoprim-sulfamethoazole (Septra)
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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
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22
Q

Gram-Negative Cocci (2 examples)

A
  • Neisseria gonorrhoeae
  • Neisseria meningiditis
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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
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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**
  • tx: 3rd generation cephalosporins (ceftriaxone)
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25
Q

Gram-negative bacilli (8 examples)

A
  • E. coli
  • Klebsiella
  • Salmonella
  • Vibrio cholerae
  • Shigella
  • Campylobacter jejuni
  • Helicobacter pylori
  • Bordatella pertussis
  • Pseudomonas aeruginosa
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26
Q

E. coli

A
  • gram-negative bacilli
  • mobile
  • mode of transmission:
    • fecal-oral route
  • causes infections such as:
    • 5 major GI infections
        1. enteropathogenic
        1. enterotoxigenic: **most common cause of travelers diarrhea** Heat Labile Toxin: 2nd messenger cAMP →loss of electrolytes and water →secretory diarrhea
      • Heat Stable Toxin
        1. enteroinvasive
        1. enterohemorrhagic: shiga toxin: inhibits protein synthesis (leads to apoptosis)
        1. enteroaggregative
  • tx: avoid abx for enterohemorrhagic E.coli in children → increase risk of hemolytic uremic syndrome
  • avoid anti-motility drugs
  • rehydration
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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
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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)
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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
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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
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31
Q

Mycobacterium

A
  • only bacteria that are acid-fast
    • resist staining in lab
  • rods
  • Mycobacterium tuberculosis
  • Mycobaterium leprae
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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
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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
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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

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35
Q

Measles

A

aka morbillivirus

negative sense, ssRNA

morbilliform rash

Koplik spots

begins on face and spreads to rest of body

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36
Q

Mumps

A

aka paramyxovirus

ssRNA

37
Q

rubella

A
  • 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 faster than measles (rubeola)
  • ​no cough, milder rash, and no koplik spots
  • tx: supportive care
38
Q

Erythema Infectiosum

A

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
Q

Rabies

A

Rhabdoviridae

bullet shaped ssRNA, negative sense

tx: rapid PEP

40
Q

HPV

A

Human papilloma virus

dsDNA

41
Q

Influenza

A

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
Q

Prion

A

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
Q

Taniea Solium

A

from pigs helminth: tape worm

can cause cysticerosis if you ingest the eggs

tx: Praziquantel

44
Q

Taenia Saginata

A

Cestodes (tapeworms)

from cows

sxs: weight loss, vomiting, appendicitis

do NOT form cysticercosis

tx: Praziquantel

45
Q

Strongyloides stercoralis

A

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
Q

Schistosomiasis

A

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
Q

Loeffler’s Syndrome

A

eosinophilic, cough up worm and swallow it

47
Q

Pinworms

A
  • Enterobious vermicularis
  • Helminth: nematode (round worm)
  • tx: Albendazole

**most common helminth infection in US** esp in children <12 yo

48
Q

Roseola

A

HHV- 6

dsDNA

**ONLY VIRAL EXANTHEM THAT BEGINS ON THE TRUNK**

HIGH fever → rash

tx: supportive

49
Q

Positive sense vs negative sense RNA

A

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
Q

Giardia

A

Giardia lamblia

  • **most common protozoan parasite in the US **
  • tx: metronidazole
51
Q

Scabies

A

Sarcoptes scabiei

type of mite

tx. Permethrin

52
Q

Candidiasis

A

yeast→Candida

  • tx: fluconazole
  • Intertriginous infections: well-demarcated erythematous patches of varying size and shape, primary patches may have satellite papules and pustules
53
Q

Histoplasmosis

A
  • Histoplasma
  • Systemic 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
Q

Cryptococcosis

A
  • 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
Q

Pneumocystis

A
  • 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
Q

Strep pneumoniae

A
  • 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
Q

Neisseria meningitidis

A
  • gram - diplococci, encapsulated
  • tx: 3rd generation cephalosporins
  • prevention: menveo and bexsero
58
Q

Neisseria gonorrhea

A
  • gram negative diplococci
  • fimbriae
  • encapsulated
  • tx: Ceftriaxone
59
Q

Diptheria

A
  • caused by Corynebacterium diptheria
    gram + rod
  • exotoxin
  • begins with sore throat and fever
  • pseudomembrane and lymphadenopathy
  • myocarditis
  • tx: Diptheria antitoxin + erythromycin or penicillin
60
Q

Shigella

A
  • 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
Q

Salmonellosis

A
  • 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
Q

Campylobacter jejuni

A
  • 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
Q

Non-invasive Diarrheas

A
  • 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, enterotoxigenic e. coli
64
Q

Invasive Diarrheas

A
  • 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
Q

Metronidazole

A

antifungal and antiprotozoal

66
Q

Botulism

A
  • 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
Q

Cholera

A
  • 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
Q

Rheumatic Fever

A
  • 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
Q

Tetanus

A
  • 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
Q

Malaria

A
  • 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
Q

Toxoplasmosis

A
  • 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
Q

Epstein Barr Virus

A
  • 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
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)
81
Q

-polyenes

A
82
Q

5- fluorocytosine

A
  • antifungal that inhibits macromolecular synthesis
    • inhibits fungal nucleid acid synthesis
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
84
Q

antifungals that form membrane pores

A
  • amphotericin B
  • nystatin
85
Q

Gram Positive Bacilli (5 examples)

A
  • Bacillus anthracis
  • Corynebacteria diptheria
  • Clostridium tetani
  • Clostridium botulinum
  • Clostridium difficile
86
Q

Yeast vs Mold Reproduction

A
  • yeast reproduction:
    • budding asexually though mitotic asexual divison
  • Mold reproduction:
    • form hyphal septa
87
Q

zika

A
  • 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

NRS 250: Exam 2 ENT and ID (9 decks)

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