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Microbiology > Chapter 18-21 > Flashcards

Chapter 18-21 Flashcards

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1
Q

Gram Positive Cocci: Staphylococcus

A

-facultative anaerobe
-commonly on skin, in nasal pharyngeal cavity
-grows well at high osmotic pressure, low moisture, UV light
-resists extremes of pH, high temperatures (up to 60 Degrees C for 60 minutes)
-produces toxins: enterotoxin, toxic shock syndrome toxin (superantigens)
-ability to develop resistance quickly
-catalase (+)
(irregular clusters)

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2
Q

Important Human Pathogens in Genus Staphylococcus

A

-Staphylococcus aureus

  • Staphylococcus epidermidis
  • Staphylococcus capitis
  • Staphylococcus hominis
  • Staphylococcus saprophyticus
  • S. aureus is most important human pathogen
  • responsible for large number of deaths and nosocomial infections annually
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3
Q

Most Important Human Pathogen

A

S. aureus

-coagulase (+)

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4
Q

Test for differentiating the genus Staphylococcus from Streptococcus

A

catalase test

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5
Q

Test for differentiating S. aureus from other Staphylococci

A

coagulase test

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6
Q

90% normal microbiota on skin is what Genus and Species

A

S. epidermidis
Staphylococcus epidermidis
(coagulase (-))

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7
Q

S. epidermidis Catalase (+) or (-)

A
  • Catalase (-)

- 90% normal microbiota on skin

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8
Q

Major virulence factors of Staphylococcus aureus: Coagulase

A
  • enzyme

- coagulates blood plasma

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9
Q

Major virulence factors of Staphylococcus aureus: Hyaluronidase

A
  • enzyme

- digests connective tissue of the host

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10
Q

Major virulence factors of Staphylococcus aureus: Staphylokinase

A
  • enzyme

- digests blood clots

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11
Q

Major virulence factors of Staphylococcus aureus: Lipase

A
  • enzyme

- digests oils, allowing bacteria to more easily colonize the skin

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12
Q

Major virulence factors of Staphylococcus aureus: Penicillinase

A
  • enzyme

- inactivates penicillin, rendering the bacterium resistant

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13
Q

Major virulence factors of Staphylococcus aureus: Hemolysins (alpha, beta, gamma)

A
  • toxin

- lyse red blood cells

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14
Q

Major virulence factors of Staphylococcus aureus: Leukocidin

A
  • toxin

- lyses neutrophils and macrophages

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15
Q

Major virulence factors of Staphylococcus aureus: Enterotoxins

A
  • toxin

- induce nausea, vomiting, and diarrhea

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16
Q

Major virulence factors of Staphylococcus aureus: Exfoliative toxins (A, B)

A
  • toxin

- cause desquamation of the skin

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17
Q

Major virulence factors of Staphylococcus aureus: Toxic shock syndrome toxin

A
  • toxin

- induces fever, vomiting, rash, organ damage

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18
Q

Diseases caused by Staphylococci

A
  • Staphylococcal intoxication
  • Pharyngitis (inflammation of pharynx; condition)
  • Pneumonia (something in lungs; condition)
  • Meningitis (condition- dont know what caused it)
  • Follicitis (hair follicle; condition)
  • Furuncle (boil)
  • Carbuncle (deep infection with staphylococcus)
  • Newborn impetigo
  • Scalded skin syndrome
  • Toxic shock syndrome
  • Bacterial endocarditis
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19
Q

Gram Positive Cocci: Streptococcus

A
  • facultative anaerobe
  • ferment various sugars; produce lactic acid
  • non-spore forming; nonmotile; can form capsules or slime layers
  • do not produce catalase but do have a peroxidase system for inactivating hydrogen peroxide so can survive in presence of oxygen
  • responsible for greater variety of diseases than any other group
  • produce toxins: erythrogenic, exotoxin A (superantigen)
  • cell wall components: M protein and others
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20
Q

Gram Positive Cocci: Streptococcus: Two Classification Systems

A
  • Lancefield Classification System (GAS, GBS)

- Classification according to action on blood agar

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21
Q

GAS produce major extracellular toxins: Enzymes that…

A

(streptococcus pyogenes)

  • destroy connective tissue of host (hyaluronidase)
  • destroy phagocytes that ingest them
  • destroy clots (fabrinolysins: Streptokinase)
  • destroy RBC’s (hemolysins)(Streptolysins: SLO + SLS; both rapidly injure cells and tissues including leukocytes, liver and muscle)
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22
Q

Lancefield Classification System

A
  • Rebecca Lancefield 1930s
  • divided streptococcal isolates into different alphabetically named groups
  • based on cell surface carbohydrates
  • GAS (streptococcus pyogenes)
  • GBS (streptococcus agalactiae)
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23
Q

Important Human Pathogens in Genus Streptococcus

A
  • Streptococcus pyogenes (GAS)
  • Streptococcus agalactiae (GBS)
  • Streptococcus mutans (D)
  • Streptococcus pneumoniae
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24
Q

Hemolytic Classification of Strep: Beta hemolytic Streptococci

A
  • completely breakdown hemoglobin
  • results in clear ring around colonies if grown on blood agar
  • S. pyogenes
  • S. agalactiae
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25
Q

Hemolytic Classification of Strep: Alpha hemolytic Streptococci

A
  • incomplete breakdown of hemoglobin
  • results in green ring around colonies
  • S. pneumoniae
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26
Q

Streptococcal cell surface antigens and virulence factors: M protein

A
  • spiky cell wall surface projections contribute to virulence by resisting phagocytosis and improving adherence; heat, acid resistant.
  • 80 different subtypes exist
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27
Q

Diseases Caused by Streptococci

A
  • Streptococcal pharyngitis
  • Pneumonia
  • Pneumococcal meningitis
  • Dental Caries
  • Non newborn impetigo
  • Scarlet fever
  • Erysipelas
  • Necrotizing fasciitis
  • Cellulitis
  • Neonatal sepsis
  • Puerperal fever
  • Bacterial endocarditis
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28
Q

Post Strep Complications

A
  • Initial GAS (streptococcus pyogenes) infection may lead to sequelae that appear weeks later. Pathology due to response of bodys immune system to strep antigens
  • Rheumatic Fever (RF)
  • Autoimmune complication
  • 10% Sydenhams chorea (neurological disorder of childhood)
  • acute Glomerulonephritis (inflammation of kidney)
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29
Q

Gram Positive Cocci: Enterococcus

A
  • Gastrointestinal tract, vagina, oral cavity
  • opportunistic pathogen; nosocomial infections
  • hardy, persists as contaminants in hospital environment, on hands, beds, as fecal aerosol
  • responsible for infections of surgical wounds, UTI’s, Septicemia from indwelling catheters
  • now resistant to most antibiotics
  • VRE (Vancomycin resistant enzyme)
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30
Q

Gram Negative Cocci: Neisseria

A

-N. meningitidis (meningococcus)
-N. gonorrhoeae (gonococcus)
-Factors contributing to pathogenicity
>multiple fimbriae
>protease cleaves secretory antibody (IgA) on mucosa
-Treatment:
>currently, many isolates resistant to penicillin
>often occurs as co infection with other STD
>multi-drug treatment: eg a cephalosporin + tetracycline

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31
Q

Neisseria: Factors contributing to Pathogenicity: Multiple Fimbriae

A
  • have receptors for human mucus membranes
  • found in mucosal cells of genitourinary tract, eye, rectum, and throat
  • besides role in attachment, fimbriae slow phagocytosis by macrophages and neutrophils
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32
Q

Gram Positive Bacilli: (Endospore- formers):

Bacillus

A
  • facultative anaerobe

- B. anthracis, B. cereus, B. Subtilis

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33
Q

Gram Positive Bacilli: (Endospore- formers): Clostridium

A
  • obligate anaerobe
  • C. tetani (cause tetanus; not treatable but preventable with tetanus shot; produces exotoxin Tetanospasmin)
  • C. botulinum (exotoxin, neurotoxin, blocks contraction, flasid (relaxation/weak))
  • C. difficile (effect G.I. tract, diarrhea; Treatment: fecal transplant)
34
Q

Most potent toxin is…

A

alpha toxin

  • RBC rupture
  • Edema
  • Tissue destruction
35
Q

Clostridium tetani produces exotoxin…

A

Tetanospasmin: Spastic Paralysis

36
Q

Gram Positive Bacilli: (Non-Endospore formers): Corynebacterium diptheriae

A
  • irregular: (pleomorphic; stain unevenly)
  • club shaped; snapping binary fission (V); palisades (line in a row next to each other)
  • leather like sheath forms in throat (local infection); toxin invades organs (toxemia); prophage has toxin genes; cutaneous infection emerging; DTaP (toxoid); DAT (antitoxin)
37
Q

Gram Positive Bacilli (Non-Endospore formers): Propionibacterium acnes

A
  • irregular: (pleomorphic; stain unevenly)
  • cause acne
  • metabolizes sebum
38
Q

Gram Positive Bacilli: (Non-Endospore Formers): Listeria Monocytogenes

A
  • Regular: (stain uniformly; no pleomorphic shapes)
  • Psychrophile; not fastidious; resistant to cold, heat, salt, pH extremes and bile
  • An intracellular pathogen for a part of its life cycle; induces its own phagocytosis, replicates in host cell; moves from cell to cell to avoid immune defense; primary reservoir: food + water; secondary: animals; Listeriosis #2 in food fatality
39
Q

Gram Positive Bacilli: (Non-Endospore Formers): Lactobacillus

A

L. acidophilus

40
Q

Gram Positive Bacilli: (Non-Endospore formers): Gardnerella

A
  • gram variable
  • normally inhabits vagina at pH 3.8; at high pHs interacts with anaerobic bacteria to cause vaginitis
  • symptoms: “clue cells” and fishy odor
41
Q

Mycobacterium

A
  • Mycobacterium spp.
  • M. tuberculosis, M. leprae, M. bovis, M. avium-intracellulare (mai)
  • aerobic, non-endospore former
  • no capsules, no flagella
  • usually contains granules and vacuoles
  • slow grower; (2 hours to several days)
  • acid fast: distinctive cell wall resembles gram (-) but LPS replaced mycolic acid which forms a waxy, water resistant layer
  • drug resistant
  • MDR strains emerging
42
Q

Virulence Factors of Mycobacterium

A
  • wax (resists desiccation; mycolic acid which forms a waxy, water resistant layer; replaces LPS on cell wall)
  • cord factor (prevent digestion by macrophage lysosomes, cord formation in infected tissue)
  • massed filaments stain red-acid fast
43
Q

Mycobacterium: tuberculosis transmission

A
  • inhaled bacilli (fine droplets of respiratory mucus suspended in air)
  • dried phlegm (bacilli may survive 8 months)
44
Q

Mycobacterium tuberculosis treatment

A

INH + Rifampin

45
Q

Mycobacterium tuberculosis

A
  • opportunistic infection
  • host susceptibility affected by presence of other illness (i.e. HIV)
  • debilitation of the immune system
  • inadequate nutrition or malnutrition
  • overcrowding
  • poor access to medical care
  • lung damage
  • stress
  • genetics
46
Q

Tuberculosis

A
  • initial contact
  • infection
  • latency (bacilli go dormant in lungs; carrier state without symptoms may last for many years; TB test (+)
  • Disease (tuberculosis)
47
Q

Mycobacterium leprae

A
  • Leprosy or Hansen’s Disease
  • Transmitted by contact with exudates (a mass of cells and fluid that has seeped out of blood vessels or an organ)
  • Treatment: rifampin + dapsone + clofazimine
  • mild; no longer fatal (with treatment)
  • Lepromin test
  • If effective cellular immunity, skin discoloration (tuberculoid form)
  • If ineffective, disfiguring nodules and tissue necrosis (rotting) (progressive or lepromatous form)
48
Q

Gram Negative Aerobic Bacilli: Brucella spp.

A
  • zoonosis
  • “undulating fever” (105 Degrees F)
  • B. abortus (affects cows)
  • B. suis (affects pigs)
  • B. melitensis (affects goats)
  • B. rangiferi
49
Q

Gram Negative Aerobic Bacilli: Bordetella pertussis

A
  • causes whooping cough or Pertussis
  • acute respiratory syndrome in babies; may be mild in adults
  • Transmission: direct contact with inhaled respiratory droplets given off during coughing state of infection
  • Virulence Factors: adhesion molecules bind specifically to ciliated respiratory cells; toxins destroy and dislodge ciliated cells
  • Stages: catarrhal (coughing), paroxymal (seizure part)
  • acellular vaccine (aP)
  • Treatment: azithromycin (1 week)
50
Q

Virulence

A

the severity or harmfulness of a disease or poison

51
Q

Bordetella pertussis Transmission

A

(whooping cough or pertussis)

direct contact with inhaled respiratory droplets given of during coughing stage of infection

52
Q

Bordetella pertussis virulence factors

A

adhesion molecules bind specifically to ciliated respiratory cells; toxins destroy + dislodge ciliated cells

53
Q

Bordetella pertussis Treatment

A

azithromycin (1 week)

54
Q

Gram Negative Aerobic Bacilli: Pseudomonas

A
  • opportunistic pathogen
  • Otitis externa (swimmers ear); respiratory infections; burn infections
  • Pyocyanin (blue green pus)
  • actively grows in (QUATS)
55
Q

Gram Negative Aerobic Bacilli: Francisella tularensis

A
  • Tularemia; zoonotic disease; associated with rabbits
  • Transmitted by contact, ingestion, bite, vector, inhalation
  • Extremely infectious: infective dose 10 to 50 organisms
  • Intracellular pathogen; spreads within macrophages
  • Pulmonary form 10% mortality rate
  • Treatment: Gentamycin, docycycline
56
Q

Gram Negative Aerobic Bacilli: Legionella pneumoniae

A
  • Legionellosis
  • prefers charcoal yeast agar
  • motile; no capsule
  • Transmitted through a/c cooling towers, warm water supply lines, air ducts, spas, tap water, supermarket misting vegetable sprayers, decorative fountains
  • Mortality rate: 3% to 30%
  • Treatment: erythromycin alone or in combination with rifampin
  • Control: Chlorination
57
Q

Gram Negative Aerobic Bacilli: Acinetobacter baumannii

A
  • Greek name for “motionless”
  • pleomorphic; resembles H. influenzae
  • enters body through open wounds, catheters, breathing tubes
  • usually infects immune compromised; opportunistic
  • colonization no threat to non compromised people, but colonized health care workers and hospital visitors carry + transmit bacteria
  • frequently causes nosocomial infections
  • aka “Iraqibacter” (spread via widespread contamination of field hospitals)
  • MDRAB (Genome contains alien DNA gained through horizontal gene transfer)
  • Treatment: imipenem, polymyxins
58
Q

Gram Negative Facultative Anaerobic Bacilli: Family Enterobacteriaceae “Enterics”

A
  • GI tract inhabitants: some permanent, some transient, some only if diseased
  • Bacteriocins
  • Many have fimbriae; may cause UTI’s
  • Most frequent cause of diarrheal illnesses
  • identification involves selective media to inhibit normal microbiota and encourage pathogens
59
Q

Family Enterobacteriaceae “Enterics” Includes….

A
  • Escherichia coli
  • Shigella spp.
  • Salmonella
  • Klebsiella pneumoniae
  • Serratia marcensens
  • Proteus spp
  • Yersinia spp. (Y. pestis causes bubonic plague)
60
Q

Yersinia pestis

A

-nonenteric
-Virulence factors: capsule protects against phagocytosis, endotoxin, coagulase
-Bubonic plague or black death
-Symptoms: Bubo (swollen lymph nodes); hemorrhaging under skin
-Transmission:
>Vector- rat flea Xenopsylla cheopsis = septicemic plague
>Inhalation- pneumonic plague

61
Q

Gram Negative Facultative Anaerobic Bacilli: Vibrio

A
  • V. cholerae: “rice water stools”

- v. parahaemolyticus: halophile; 10 minute generation time

62
Q

Gram Negative Facultative Anaerobic Bacilli: Pasteurella

A

pathogen of domestic animals; also humans

63
Q

Gram Negative Facultative Anaerobic Bacilli: Haemophilus Influenzae

A
  • “blood lover”. misnamed; HIB
  • causes respiratory infection, meningitis; ear aches
  • does not cause the flu
64
Q

Spirochetes

A

Gram Negative; flexible helical motile by axial filaments

  • Treponema pallidum
  • Borrelia burgdorferi
  • Leptospira spp
65
Q

Spirochete: Treponema pallidum

A
  • Syphilis, Congenital Syphilis
  • Chancre (sore)–> Rash–> Latent–> Gummas (rubbery gummas; die of brain disease)
  • Penicillin G
66
Q

Spirochete: Borrelia burgdorferi

A
  • Borreliosis or Lyme Disease
  • cold (rash), neuro/cardio symptoms, arthritis
  • Treatment: tetracycline or derivatives
  • Transmitted by Vector: deer tick Ixodes
67
Q

Spirochete: Leptospira spp

A
  • Transmitted in dried urine of domestic pets (contact with mucus membranes or skin abrasions)
  • Principle targets: kidneys, liver, eyes, brain
  • Symptoms: sudden high fever, chills, headache, muscle aches, conjunctivitis, vomiting
  • Treatment: Penicillin or Tetracycline
68
Q

Gram Negative Curviform Bacilli: Campylobacter jejuni

A

gastrointestinal infections

69
Q

Gram Negative Curviform Bacilli: Helicobacter pylori

A

causes stomach ulcers

70
Q

Gram Negative Anaerobic Bacilli: Bacteroides

A

human intestinal tract; peritonitis

71
Q

Order Rickettsiales

A
  • Gram (-) bacilli (rod-shaped)
  • Transmitted usually by arthropod vector
  • Grows intracellularly in host cell; responds to tetracycline
  • Rickettsia spp. (R. ricketsii, R. prowazeki, R. typhi)
  • Ehrlichia spp.
  • Bartonella henselae
72
Q

Order Rickettsiales: R. rickettsii

A

Rocky Mountain spotted fever

-dermacentor variables (dog tick)

73
Q

Order Rickettsiales: R. prowazeki

A

(Louse-borne Typhus aka epidemic typhus)

Pediculus humanus corporis

74
Q

Order Rickettsiales: R. typhi

A

Endemic Murine typhus

  • host reservoir: rodents
  • Vector: Xenopsylla cheopsis (rat flea)
75
Q

Order Rickettsiales: Ehrlichia spp

A
  • Gram (-), rickettsia-like, obligate intracellular bacterium
  • Tickborne diseases with host reservoir being animals, especially deer
  • Two distinct forms: HGE, HME
76
Q

Order Rickettsiales: Bartonella henselae

A
  • Aerobic, Gram (-) bacterium

- Transmitted by bite or scratch (cat to cat by flea)

77
Q

Family Chlamydiaciae

A

-Gram (-) coccoid
-Transmitted by air or direct contact (STD)
-Grows intracellularly in a host cell
-3 stages: reticulate bodies that reproduce in host; intermediate bodies; elementary bodies are infectious)
-Two Genera:
>Chlamydia
>Chlamydophila

78
Q

Family Chlamydiaciae: Chlamydia

A

Chlamydia trachomatis

79
Q

Family Chlamydiaciae: Chlamydophila

A
  • Chlamydophila psittaci

- Chlamydophila pneumoniae

80
Q

Mycoplasma

A
  • Mycoplasma pneumoniae
  • no cell walls; pleomorphic; very small
  • Gram (-) type reaction
  • requires sterols in medium (does not produce its own sterols)
  • causes Primary Atypical Pneumonia aka Walking Pneumonia
  • Responds to tetracycline
81
Q

Gram Negative Aerobic Bacilli

A
  • Francisella tularensis
  • Legionella pneumoniae
  • Acinetobacter baumannii
  • Brucella spp
  • Bordetella pertussis
  • Pseudomonas

Microbiology (20 decks)

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