Chapter 18-21 Flashcards
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)
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
3
Q
Most Important Human Pathogen
A
S. aureus
-coagulase (+)
4
Q
Test for differentiating the genus Staphylococcus from Streptococcus
A
catalase test
5
Q
Test for differentiating S. aureus from other Staphylococci
A
coagulase test
6
Q
90% normal microbiota on skin is what Genus and Species
A
S. epidermidis
Staphylococcus epidermidis
(coagulase (-))
7
Q
S. epidermidis Catalase (+) or (-)
A
- Catalase (-)
- 90% normal microbiota on skin
8
Q
Major virulence factors of Staphylococcus aureus: Coagulase
A
- enzyme
- coagulates blood plasma
9
Q
Major virulence factors of Staphylococcus aureus: Hyaluronidase
A
- enzyme
- digests connective tissue of the host
10
Q
Major virulence factors of Staphylococcus aureus: Staphylokinase
A
- enzyme
- digests blood clots
11
Q
Major virulence factors of Staphylococcus aureus: Lipase
A
- enzyme
- digests oils, allowing bacteria to more easily colonize the skin
12
Q
Major virulence factors of Staphylococcus aureus: Penicillinase
A
- enzyme
- inactivates penicillin, rendering the bacterium resistant
13
Q
Major virulence factors of Staphylococcus aureus: Hemolysins (alpha, beta, gamma)
A
- toxin
- lyse red blood cells
14
Q
Major virulence factors of Staphylococcus aureus: Leukocidin
A
- toxin
- lyses neutrophils and macrophages
15
Q
Major virulence factors of Staphylococcus aureus: Enterotoxins
A
- toxin
- induce nausea, vomiting, and diarrhea
16
Q
Major virulence factors of Staphylococcus aureus: Exfoliative toxins (A, B)
A
- toxin
- cause desquamation of the skin
17
Q
Major virulence factors of Staphylococcus aureus: Toxic shock syndrome toxin
A
- toxin
- induces fever, vomiting, rash, organ damage
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
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
20
Q
Gram Positive Cocci: Streptococcus: Two Classification Systems
A
- Lancefield Classification System (GAS, GBS)
- Classification according to action on blood agar
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)
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)
23
Q
Important Human Pathogens in Genus Streptococcus
A
- Streptococcus pyogenes (GAS)
- Streptococcus agalactiae (GBS)
- Streptococcus mutans (D)
- Streptococcus pneumoniae
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
25
Hemolytic Classification of Strep: Alpha hemolytic Streptococci
- incomplete breakdown of hemoglobin
- results in green ring around colonies
- S. pneumoniae
26
Streptococcal cell surface antigens and virulence factors: M protein
- spiky cell wall surface projections contribute to virulence by resisting phagocytosis and improving adherence; heat, acid resistant.
- 80 different subtypes exist
27
Diseases Caused by Streptococci
- Streptococcal pharyngitis
- Pneumonia
- Pneumococcal meningitis
- Dental Caries
- Non newborn impetigo
- Scarlet fever
- Erysipelas
- Necrotizing fasciitis
- Cellulitis
- Neonatal sepsis
- Puerperal fever
- Bacterial endocarditis
28
Post Strep Complications
- 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)
29
Gram Positive Cocci: Enterococcus
- 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)
30
Gram Negative Cocci: Neisseria
-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
31
Neisseria: Factors contributing to Pathogenicity: Multiple Fimbriae
- 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
32
Gram Positive Bacilli: (Endospore- formers):
| Bacillus
- facultative anaerobe
| - B. anthracis, B. cereus, B. Subtilis
33
Gram Positive Bacilli: (Endospore- formers): Clostridium
- 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
Most potent toxin is...
alpha toxin
- RBC rupture
- Edema
- Tissue destruction
35
Clostridium tetani produces exotoxin...
Tetanospasmin: Spastic Paralysis
36
Gram Positive Bacilli: (Non-Endospore formers): Corynebacterium diptheriae
- 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
Gram Positive Bacilli (Non-Endospore formers): Propionibacterium acnes
- irregular: (pleomorphic; stain unevenly)
- cause acne
- metabolizes sebum
38
Gram Positive Bacilli: (Non-Endospore Formers): Listeria Monocytogenes
- 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
Gram Positive Bacilli: (Non-Endospore Formers): Lactobacillus
L. acidophilus
40
Gram Positive Bacilli: (Non-Endospore formers): Gardnerella
- 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
Mycobacterium
- 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
Virulence Factors of Mycobacterium
- 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
Mycobacterium: tuberculosis transmission
- inhaled bacilli (fine droplets of respiratory mucus suspended in air)
- dried phlegm (bacilli may survive 8 months)
44
Mycobacterium tuberculosis treatment
INH + Rifampin
45
Mycobacterium tuberculosis
- 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
Tuberculosis
- initial contact
- infection
- latency (bacilli go dormant in lungs; carrier state without symptoms may last for many years; TB test (+)
- Disease (tuberculosis)
47
Mycobacterium leprae
- 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
Gram Negative Aerobic Bacilli: Brucella spp.
- zoonosis
- "undulating fever" (105 Degrees F)
- B. abortus (affects cows)
- B. suis (affects pigs)
- B. melitensis (affects goats)
- B. rangiferi
49
Gram Negative Aerobic Bacilli: Bordetella pertussis
- 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
Virulence
the severity or harmfulness of a disease or poison
51
Bordetella pertussis Transmission
(whooping cough or pertussis)
| direct contact with inhaled respiratory droplets given of during coughing stage of infection
52
Bordetella pertussis virulence factors
adhesion molecules bind specifically to ciliated respiratory cells; toxins destroy + dislodge ciliated cells
53
Bordetella pertussis Treatment
azithromycin (1 week)
54
Gram Negative Aerobic Bacilli: Pseudomonas
- opportunistic pathogen
- Otitis externa (swimmers ear); respiratory infections; burn infections
- Pyocyanin (blue green pus)
- actively grows in (QUATS)
55
Gram Negative Aerobic Bacilli: Francisella tularensis
- 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
Gram Negative Aerobic Bacilli: Legionella pneumoniae
- 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
Gram Negative Aerobic Bacilli: Acinetobacter baumannii
- 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
Gram Negative Facultative Anaerobic Bacilli: Family Enterobacteriaceae "Enterics"
- 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
Family Enterobacteriaceae "Enterics" Includes....
- Escherichia coli
- Shigella spp.
- Salmonella
- Klebsiella pneumoniae
- Serratia marcensens
- Proteus spp
- Yersinia spp. (Y. pestis causes bubonic plague)
60
Yersinia pestis
-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
Gram Negative Facultative Anaerobic Bacilli: Vibrio
- V. cholerae: "rice water stools"
| - v. parahaemolyticus: halophile; 10 minute generation time
62
Gram Negative Facultative Anaerobic Bacilli: Pasteurella
pathogen of domestic animals; also humans
63
Gram Negative Facultative Anaerobic Bacilli: Haemophilus Influenzae
- "blood lover". misnamed; HIB
- causes respiratory infection, meningitis; ear aches
- does not cause the flu
64
Spirochetes
Gram Negative; flexible helical motile by axial filaments
- Treponema pallidum
- Borrelia burgdorferi
- Leptospira spp
65
Spirochete: Treponema pallidum
- Syphilis, Congenital Syphilis
- Chancre (sore)--> Rash--> Latent--> Gummas (rubbery gummas; die of brain disease)
- Penicillin G
66
Spirochete: Borrelia burgdorferi
- Borreliosis or Lyme Disease
- cold (rash), neuro/cardio symptoms, arthritis
- Treatment: tetracycline or derivatives
- Transmitted by Vector: deer tick Ixodes
67
Spirochete: Leptospira spp
- 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
Gram Negative Curviform Bacilli: Campylobacter jejuni
gastrointestinal infections
69
Gram Negative Curviform Bacilli: Helicobacter pylori
causes stomach ulcers
70
Gram Negative Anaerobic Bacilli: Bacteroides
human intestinal tract; peritonitis
71
Order Rickettsiales
- 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
Order Rickettsiales: R. rickettsii
Rocky Mountain spotted fever
| -dermacentor variables (dog tick)
73
Order Rickettsiales: R. prowazeki
(Louse-borne Typhus aka epidemic typhus)
| Pediculus humanus corporis
74
Order Rickettsiales: R. typhi
Endemic Murine typhus
- host reservoir: rodents
- Vector: Xenopsylla cheopsis (rat flea)
75
Order Rickettsiales: Ehrlichia spp
- Gram (-), rickettsia-like, obligate intracellular bacterium
- Tickborne diseases with host reservoir being animals, especially deer
- Two distinct forms: HGE, HME
76
Order Rickettsiales: Bartonella henselae
- Aerobic, Gram (-) bacterium
| - Transmitted by bite or scratch (cat to cat by flea)
77
Family Chlamydiaciae
-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
Family Chlamydiaciae: Chlamydia
Chlamydia trachomatis
79
Family Chlamydiaciae: Chlamydophila
- Chlamydophila psittaci
| - Chlamydophila pneumoniae
80
Mycoplasma
- 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
Gram Negative Aerobic Bacilli
- Francisella tularensis
- Legionella pneumoniae
- Acinetobacter baumannii
- Brucella spp
- Bordetella pertussis
- Pseudomonas
