Intro to Bacteria Part 1 Flashcards
(126 cards)
1
Q
Prokaryote vs. Eukaryote (generally)
A
eukaryotes contain membrane bound nuclei, while prokaryotes do not
2
Q
Archaeon
A
microorganisms found in extreme environments; possibly the earliest forms of cellular life on earth
3
Q
Gram positive stain color
A
Blue
4
Q
Gram negative stain color
A
Red
5
Q
Gram positive cell wall
A
very thick cell wall with extensive amino acid cross-linking; made of peptidoglycan, teichoic acid, polysaccharides and other proteins
6
Q
Gram negative cell wall
A
simple cross linking pattern; cytoplasmic membrane, peptidoglycan layer, THIN peptidoglycan layer (no teichoic acid), LPS layer, porins in outer membrane
7
Q
LPS constituents
A
O-specific side chain/O-antigen, core polysaccharide, Lipid A
8
Q
Gram negative endotoxin
A
Lipid A; causes fever, diarrhea, endotoxic shock
9
Q
What can pass through a G+ cell wall?
A
antibiotics, dyes, detergents
10
Q
What substances cannot pass through G- cell wall?
A
negatively charged, antibiotics that attack peptidoglycan
11
Q
Key differences between G+ and G- cell wall?
A
G+: 2 layers, low lipid content, no endotoxin, no porin, vulnerable to lysozyme and penicillin
G-: 3 layers, high lipid content, Lipid A toxin, porin channels, resistant to lysozyme and penicillin
12
Q
6 Classic most medically relevant G+ pathogens
A
Streptococcus, Staphylcoccus, Bacillus and Clostridium (spores), and Corynebacterium and Listeria (non spores)
13
Q
G- cocci
A
Neisseria, Moraxella
14
Q
G- spiral shaped
A
Spirochetes (Treponema pallidum)
15
Q
Mycobacteria unique features
A
weakly G+ but stain better with acid-fast stain
16
Q
Spirochetes unique features
A
G- wall but must be seen with dark field microscope (size); contain additional outer membrane with very few proteins and periplasmic flagella
17
Q
Mycoplasma unique features
A
no cell wall, not G+ or G-
18
Q
G+ obligate aerobes
A
Nocardia, Bacillus cereus
19
Q
G+ Facultative anaerobes
A
Staphylococcus, Bacillus anthracis, Cornyebacterium, Listeria, Actinomyces
20
Q
G+ Microaerophilic
A
Enterococcus, Sterptococcus
21
Q
G+ Obligate anaerobes
A
Clostridium
22
Q
G- obligate aerobes
A
Neisseria, Pseudomonas, Bordetella, Legionella, Brucella
23
Q
G- facultative anaerobes
A
most G- rods
24
Q
G- Microaerophilic
A
Spirochetes (Treponema, Borrelia, Leptospira), Campylobacter
25
G- Obligate anaerobes
Bacteroides
26
Acid-fast obligate aerobes
Mycobacterium, Nocardia
27
Oxygen spectrum of Mycoplasma
Facultative anaerobe
28
Obligate aerobes
glycolysis, Krebs, and ETC
29
Facultative anaerobes
aerobic bacteria that contain catalase and superoxide dismutase; CAN grow in absence of oxygen
30
Microaerophilic bacteria
no electron transport system, tolerate low amounts of oxygen and have superoxide dismutase
31
Obligate anaerobes
No enzymes to defend against oxygen, does not like oxygen
32
Virulence definition
degree of organism pathogenicity
33
pili
straight filaments arising from bacterial cell wall, serve as adherence factors
34
organisms with pili and cells they attach to
N. gonorrhea: cervical and bucal cells
E. coli and C. jejuni: intestinal epithelium
B. pertussis: ciliated respiratory cells
35
Capsules
Protective walls around cell membranes of bacteria composed of simple sugars
36
Capsule of Bacillus anthracis
capsule made up of amino acid residues
37
Why do capsules contribute to the virulence of an organism?
Neutrophils and macrophages are unable to phagocytize encapsulated bacteria
38
Stains that enable doctors to visualize capsules
India Ink stain, Quellung reaction
39
India ink stain
stain not taken up by capsule, appears as a transparent halo around cell; Cryptococcus
40
Quellung reaction
bacteria mixed with abs, capsule can swell with water
41
Endospores
formed by G+ bacillus and clostridium; metabolically dormant forms resistant to heat, cold, drying and chemical agents
42
Endospore protective coat consists of
cell membrane, peptiodglycan, cell membrane, keratin-like protein, exosporium
43
When do spores form?
shortage of needed nutrition, will become active again when appropriate nutrition is available
44
Exotoxins
proteins released by G+ and G- bacteria that may cause disease manifestations (anthrax, botulism, tetanus, cholera)
45
Neurotoxin
tetanus toxin and botulinum toxin; act on nerves or motor endplates to cause paralysis
46
Enterotoxins
exotoxins that act on GI; inhibit NaCl resorption, activate NaCl secretion or kill epithelial cells
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Two disease manifestations of enterotoxins
Infectious diarrhea (E. coli, V. cholera, C. jejuni, S. dysenteriae), Food poisoning (toxin from food, B. cereus, S. aureus)
48
Pyrogenic exotoxins
cause rash, fever, toxic shock; S. aureus, S. pyogenes
49
Tissue Invasive exotoxins
allow bacteria to destroy and tunnel through tissues
50
Endotoxins
Lipid A, released when bacteria undergoes lysis, but can be shed from living bacteria; normal part of membrane that sheds off
51
Septic shock
sepsis that results in low BP and organ dysfunction
52
TNF
tumor necrosis factor/cachexin; triggers release of IL-1
53
IL-1
triggers release of other cytokines and PGs, vasodilation, hypotension and organ system dysfunction
54
Methods of genetic exchange between bacteria
transformation, transduction, conjugation, transposons
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Transformation
uptake of DNA fragments from one bacterium released during lysis
56
Transduction
bacteriophage carries piece of bacterial DNA from one bacterium to another
57
Virulent phage
infects, reproduces, then lyses bacteria; generalized transduction
58
Temperate phage
infect bacteria, but DNA will become incorporated into the bacteria DNA (time bomb); specialized transduction
59
Lysogenic immunity
term used to describe ability of an integrated bacteriophage to block a subsequent infection by a similar phage
60
Generalized transduction
bacterial DNA mispackaged into phage, which can then go and infect another bacteria without causing it's death
61
Conjugation
sex pilus forms and allows for efficient exchange of plasmid/genetic material between bacteria
62
Transposons
pieces of DNA that insert themselves into chromosome without having homology, often responsible for drug resistance
63
Agents and methods used to identify pathogens?
smears, gram staining, cultures, molecular techniques, serology, survey for ab positivity
64
Potential pathogens
bacteria, viruses, fungi, parasites, prions, mites, etc.
65
Pros of bacterial cultures
high specificity, isolates can be tested for ab sensitivity, enables biochem characterization of phenotype, less expensive, does not require special workflow, does not require specialized instrumentation
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Cons of bacterial cultures
low sensitivity, cannot detect nonviable bacteria, biochem phenotype may not agree with genotype, longer time to result for slow-growing bacteria, biosafety concern
67
Pros of NAT methods
high sensitivity, rapid turnaround time, detection of nonviable bacteria, reduced biosafety concern, detection of ab-resistant bacteria without an initial culture
68
Cons of NAT methods
false positives due to cross reaction, false-negatives, genotype may not agree with biochem results, requires special instrumentation and training, few tests for ab sensitivity are available
69
Differentiating Staph and Strep
Staph: cocci cluster together, catalase positive (Staff has a Cat)
Strep: cocci form a strip, catalase negative
70
Hemolytic reactions of strep
Beta-hemolytic: completely lyse RBCs on blood agar
Alpha-hemolytic: partially lyse RBC
Gamma-hemolytic: unable to hemolyze ("non-hemolytic" streptococci)
71
C carbohydrate
Carb found on cell wall of Strep
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Group A B-hemolytic Streptococci aka
Streptococcus pyogenes
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Diseases associated with S. pyogenes
strep throat, scarlet fever, rheumatic fever, post-strep glomerulonephritis
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C carb Lancefield group of S. pyogenes
Lancefield group A
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M protein
Major virulence factor in S. pyogenes, inhibits complement and protects from phagocytosis
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Streptolysin O
enzyme in beta-hemolytic group A strep, inactivated by oxygen, destroys RBC and WBC, ANTIGENIC (may order ASO on pt)
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Streptolysin S
oxygen stable enzyme beta-hemolytic group A strep, not antigenic
78
Pyrogenic exotoxin
exotoxin produced by only a few strains of beta hemolytic group A strep, superstimulates T cells to pour out inflammatory cytokines
79
streptokinase
activates proteolytic enzyme plasmin, breaks up fibrin clot
80
Beta-hemolytic Grp A strep causes what diseases by local invasion or exotoxin release
Strep pharyngitis, Strep skin infection, scarlet fever, Strep TSS
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Beta hemolytic Grp A strep causes what diseases by delayed antibody mediated diseases
Rheumatic fever and glomerulonephritis
82
Sxs and tests for Strep pharyngitis
red swollen tonsils and pharynx, purulent exudate on tonsils, high temp, swollen LNs
RADT test: group A carb
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Sxs of Strep skin infections
folliculitis, pyoderma, erysipelas, cellulitis, impetigo
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Erysipelas
strep infection of superficial skin, raised, bright red rash with a sharp border that advances from the initial site of infection
85
Pyoderma
pustule on face or extremity that breaks down after 4-6 days and forms a thick crust, leaving a depigmented area
86
Necrotizing fascitis
certain strains of grp A b-hemolytic strep have M proteins that block phagocytosis; swelling, heat, redness at site of infection, large blisters form and skin and muscle may die
87
Fournier's gangrene
form of necrotizing fascitis in male genital area and perineum
88
Scarlet fever
sore throat and pyrogenic or erythrogenic toxin and fever/rash; spares the face!
89
Strep TSS
pyrogenic toxin
90
Erythema marginatum
nonpruritic rash typically occurring on trunk and extremities, not face; occurs in patients with rheumatic fever
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Tinea corporis
rounded lesion that typically has a fine scale and may cause alopecia; central clearing and raised borders; pruritic
92
Erythema migrans
bull's eye appearance, Lyme disease; central erythema and necrosis
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Erythema multiforme
maculopapular rash located on palms and feet that generally spreads; can result from drug rxn or viral and bacterial infections; bull's eye appearance, pruritic, blanches away slowly
94
Erythema nodosum
erythematous macules that are painful; usually occurs on shins
95
Rheumatic fever presentation
children 5-15 yrs of age, typically follows strep pharyngitis; fever, myocarditis, joint swelling, chorea, subcutaneous nodules, erythema marginatum
96
Acute post-strep glomerulonephritis
ab-mediated inflammatory disease of glomeruli; antigen-antibody complexes deposit in BM of glomeruli
97
Presentation of acute post-strep glomerulonephritis
child in office complaining of puffy face, dark urine; may have hypervolemia/high BP; recent history of throat or skin infection
98
Grp B Streptococci genus/species
Streptococcus agalactiae
99
Age-group most commonly affected by Grp B Strep
neonates; most common cause of neonatal meningitis, pneumonia, and sepsis
100
Grp B Strep presentation
fever, vomiting, poor feeding, irritability
101
3 most common pathogens associated with meningitis in neonates and infants <3mo?
E. coli, L. monocyotogenes, grp B Strep
102
Most common bacterial cause of meningitis later in life
Neisseria meningitides, Haemophilus influenzae
103
Viridans Grp Streptococci hemolytic rxn
alpha-hemolytic
104
Where are Viridans Grp Streptococci normally found?
GI tract, nasopharynx, gingiva
105
Associated infections of Viridans Grp Strep
dental infections, endocarditis, abscesses
106
Presentation of Subacute Bacterial Endocarditis
low-grade fever, fatigue, anemia, heart murmur secondary to valve destruction
107
Presentation of acute infective endocarditis
shaking chills, high spiking fevers, rapid valve destruction
108
Bacteria commonly found in brain or abd organ abscesses
Anginosus species (Strep. intermedius), microaerophilic
109
Grp D Strep sub groups
Enterococcus and non-enterococci
110
Hemolytic pattern of Grp D Strep
alpha- or gamma-hemolytic
111
Normal residence of enteroccoci
human intestines/normal bowel
112
Unique growth characteristics of enteroccus
ability to grow in 40% bile or 6.5% NaCl
113
Common diseases associated with Enterococcus
UTI, biliary tract infection, bacteremia, subacute bacterial endocarditis
114
Enterococcus in nosocomial infections
second to third most common cause of hospital acquired infections
115
Drug resistance of Enterococci
resistant to nost G+ bacteria; vancomycin and ampicillin, esp
116
Non-enterococci common genus/species
Strep bovis and equinis
117
Growth conditions of Strep bovis
40% bile acid (but not 6.5% salt!)
118
S. bovis in colon cancer
remarkable association, not sure if it's a cause or marker?
119
Strep pneumoniae disease manifestations
bacterial pneumonia and meningitis in adults, otitis media in kids
120
Quellung reaction for Strep pneumoniae
capsule swells
121
Optochin sensitivity for Strep pneumoniae
growth inhibited by optochin (unlike S. viridans)
122
Most common cause of pneumonia in adults
S. pneumoniae
123
Presentation of pneumococcal pneumonia
rigors, high fevers, chest pain with respirations, SOB, yellow-green sputum
124
Three organisms associated with otitis media
S. pneumoniae, H. influenzae, M. catarrhalis
125
Who is given the pneumococcal vaccine
immunocompromised, elderly, asplenic or HIV positive individuals
126
Emerging abx resistance of S pneumoniae
penicillin ,erythromycin, sulfamethoxazole, chloramphenicol
