Gram + Flashcards
(155 cards)
1
Q
gram + colour?
A
purple/blue
2
Q
Gram + - subgroups
A
- cocci
- Robs (bacilli)
- branching filaments
3
Q
gram + branching filaments - bugs (and characteristics)
A
- Actinomyces - anaerobe, not acid fast
2. Nocardia - aerobe, acid fast
4
Q
gram + robs - bugs (and characteristics)
A
- Clostiridium - spore forming, anaerobe
- Bacillus - spore forming, aerobe
- Listeria - no spore forming, tumbling motile, aerobe
- corynobacterium - no spore forming, non-motile, aerobe
5
Q
gram + cocci are divided to (and characteristics)
A
- staphylococcus (cat+, clusters)
2. streptococcus (cat-, chains)
6
Q
staphylococcus - bugs (and characteristics)
A
ALL CAT+, CLUSTERS
- S. aureus (coagulase +)
- S. epidermidis (novobiosin sensitive)
- S. saprophyticus (novobiosin resistant)
7
Q
streptococci are divided into subgroups according to (and the meaning)
A
hemolysis
- partially hemolysis (α)
- complete hemolysis (clear) (β)
- no hemolysis (γ)
8
Q
β hemolytic streptococci - bugs (and characteristics)
A
- S pyogens (group A, Bacitracin sensitive)
2. S. agalactiae (group B, Bacitracin resistant)
9
Q
γ hemolytic streptococci - bugs (and characteristics)
A
- enterococcus (E. faecalis, E. feacium) - Group D, growth in bile and 6.5% NaCL
- Nonenterococcus (Streptococcus bovis) - Group D, Growth in bile, not in 6.5 NaCL
10
Q
entrococcus - hemolysis?
A
either a- or γ- hemolytic
11
Q
α hemolytic streptococci - bugs (and characteristics)
A
- S. pneumoniae - Capsule, Optichin sensitive, Bile soluble (lysed by bile)
- Viridaans streptococci (eg. S. mutans, S. sanguinis, S. mitis) - no capsule, optochin resistant, bile soluble (lysed)
12
Q
drugs to use to differentiate gram + bugs (and how)
A
- novobiocin –> staphyloccous epidermidis is sensitive, but staphylococcus saprophyticus is resistatn
- Optichin –> Streptococcus pneumoniae is sensitive but viridans streptococci is resistant
- Bcitracin –> S pyogenes (Group A) is sensitive but S. agalactiae (Group B) is resistant
13
Q
α hemolytic bacteria - appearance and mechanism
A
Partial reduction of Hb causes greenish or broownish color without clear ring around colonies on blood agar
14
Q
β-hemolytic bacteria - appearance and mechanism
A
complete lysis form clear area of surrounding colony on blood agar
15
Q
β-hemolytic bacteria - - bugs (and characteristics)?
A
- Staphylococcus aureus (cat+, coagulase +)
- Streptococcus pyogens (cat- ,group A, Bacitracin sensitive)
- Streptococcus agalactiae (cat-, group B, Bacitracin resistant)
- Listeria - no spore forming, tumbling motility, aerobe
16
Q
staphylococcus saprophyticus - characteristics
A
gram +, cat + coag -. UREASE + cocci in clusters, novobiocin resistance
17
Q
staphylococcus saprophyticus - clinical manifestation
A
Second MCC of UNCOMPLICATED UTI in young women
18
Q
MCC and 2nd MCC of uncomplicated UTI in young women
A
- E. coli
2. staphylococcus saprophyticus
19
Q
staphylococcus saprophyticus - area of the body
A
Normal flora of female genital tract + perineum
20
Q
staphylococcus epidermidis - characteristics / area of the body (clinically relevance)
A
gram +, cat+, coag-, UREASE +, novobiocin sensitive
normal skin flora –> contaminates blood cultures
21
Q
staphylococcus epidermidis - clinical manifestations
A
infects prosthetic valves devises (hip implant, heart valve) and intravenous catheters by producing adherent biofilms
22
Q
staphylococcus epidermidis infects prosthetic valves devises (hip implant, heart valve) and intravenous catheters by
A
producing adherent biofilms
23
Q
staphylococcus aureus - characteristics
A
gram +, cat+, coagulase +, β-hemol,
24
Q
staphylococcus aureus - how to evade immune system
A
Protein A (virulence factor) binds Fc-IgG, inhibiting complement activation and phagocytosis
25
staphylococcus aureus - area of the body
commonly colonizes the nares
26
Staphylococcus aureus can cause (clinical manifestation) ..... (only the categories)
inflammatory disease
Toxin mediated disease
MRSA infection
27
staphylococcus aureus - inflammatory disease?
1. skin infection
2. organ abscesses
3. pneumonia
4. endocarditis
5. osteomyelitis
6. septic arthritis
28
staphylococcus aureus - pneumonia?
often after virus infection
29
Staphylococcal aureus toxins
1. Toxic shock syndrome toxin (TSST-1)
2. Exfoliative
3. enterotoxin
30
Staphylococcal aureus toxins and manifestations
1. Toxic shock syndrome toxin (TSST-1) --> Toxic shock syndrome: fever, rash, shock, vomiting, desquamation, end-organ failure
2. Exfoliative --> scalded skin syndrome
3. enterotoxin --> rapid onset food poisoning
31
skin infection - staphylococcus aureus can cause
1. impetigo
2. cellulitis
3. Abscess
4. Staphylococcal scalded skin syndrome
32
cellulitis is caused by
usually S. aureus or S. pyogenes
33
impetigo is caused by
usually S. aureus or S. pyogenes
34
staphylococcal scalded skin syndrome - symptoms
1. fever
| 2. generalized erythematous rash with sloughing of the upper layers of the epidermis that heals completely
35
staphylococcal scalded skin syndrome - seen in
1. newborns
2. children
3. adults with renal insufficiency
36
staphylococcal scalded skin syndrome - mechanism
exotoxin (exofliative) destroys keratinocytes attachments in stratum granulosum ONLY
37
staphylococcus aureus - MRSA - infection
important cause of serious nosocomial and community-acquired infections
38
MRSA - mechanism
resistant to methicillin and nafcillin because of altered penicillin biding protein
39
staphylococcus aureus can cause .... (categories and manifestations
A. inflammatory disea: 1. skin infection 2. organ abscesses
3. pneumonia 4. endocarditis 5. osteomyelitis
B. Toxin mediated disease: 1. TSST-1 --> Toxic shock syndrome 2. Exfoliative --> scalded skin syndrome
3. enterotoxin --> rapid onset food poisoning
C. MRSA infection: serious nosocomial and community-acquired infections
40
Toxic shock syndrome toxin (TSST-1) - mechanism of action
Binds to MCH II and TCR outside of antigen binding site (polyclonal T-cel activation)to cause overwhelming release of IL-1, IL-2, INF-γ, TNF-α --> shock
41
Toxic shock syndrome - symptoms / lab
- fever, rash, shock, vomiting, desquamation, end-organ failure
- increased AST, ALT, blirirubin
42
Toxic shock syndrome - is associated with (situations)
1. S. aureus --> vaginal tampons, nasal packing
| 2. S. pyogenes --> painful skin infection
43
S. aureus - food poisoning is due to
ingestion of preformed toxin (enterotoxin)
44
S. aureus - food poisoning - course
short incubation period (2-6h) followed by NON-BLOODY diarrhea and emesis
45
S. aureus enterotoxin - special feature
heat stable --> not destroyed by cooking
46
S. aureus - coagulase? (relevance in manifestation)
coagulase + --> forms fibrins clot around self --> abscess
47
S. pneumoniae - characteristics
gram +, cocci, α hemolytic, Capsule, Optichin sensitive, Bile soluble (lysed by bile)
48
S. pneumoniae - appearance
Lancet-shape, gram + diplococci, encapsuled
49
S. pneumoniae - clinical manifestation
A. MCC OF: 1. Meningitis 2. Otitis media (in children)
3. Pneumonia 4. Sinusitis
B. Sepsis in sickle cell and splenectomy
50
S. pneumoniae - clinical importance of capsule
no virulence without capsule
51
S. pneumoniae - virulence factor
1. capsule
| 2. IgA protease
52
S. pneumoniae - sputum?
rusty
53
S. pneumoniae - sepsis in
1. sickle cell anemia
| 2. splenectomy
54
S pneumoniae - vaccines and structure
PCV - pneumonococcal congugate vaccine (Prevnar)
| PPSV - pneumonococcal polysaccharide vaccine with no congugate protein (Pneumovax)
55
Viridans group streptococci - hemolysis? / area of the body
α / normal flora of the oropharynx
56
Viridans group streptococci - area of the body
normal flora of the oropharynx
57
Viridans group streptococci - bugs?
1. Streptococcus mutans
| 2. Streptococcus sanguinis
58
Viridans group streptococci - clinical manifestation
1. Streptococcus mutans + mitis --> dental carries
2. Streptococcus sanguinis --> sabacute bacterial endocarditis at damages heart valves
(It makes dextrans, which bind to fibrin-plaelet aggregates on damaged heart valve)
59
Viridans group streptococci - characteristics
a-hemolytic, no capsule, optochin resistant, bile insoluble (no lysed)
60
α hemolytic streptococci - bugs (and characteristics)
1. S. pneumoniae - Capsule, Optichin sensitive, Bile soluble (lysed by bile)
2. Viridaans streptococci (eg. S. mutans, s mutis, S. sanguinis) - no capsule, optochin resistant, bile soluble (lysed)
61
Streptococcus pyogenes - characteristics
cat- ,group A, Bacitracin sensitive, β-hemolytic
62
Streptococcus pyogenes can cause ...... (categories)
1. pyogenic
2. toxigenic
3. immunologic
63
Streptococcus pyogenes - pyogenic
1. pharyngitis
2. cellulitis
3. impetigo
4. erysipellas
64
Streptococcus pyogenes - toxigenic
1. scarlet fever
2. toxic shock like syndrome
3. necrotizing fascitis
65
necrotizing fascitis - definition and causes / aka / appearance / sensation
deeper tissue injury, usually from anaerobic bacteria or S. pyogenes. aka: flesh eating bacteria
appearance: bullae and purple color to the skin
sensation: crepitus (methane and CO2 production)
66
Streptococcus pyogenes - immunologic
1. rheumatic fever
| 2. acute glumorelonephritis
67
Scarlet fever - manifestation / caused by
blanching, sandpaper-like body rash, strawberry tongue and circumoral pallor in the setting of group A streptococcal pharyngitis (erytrhogenic toxin)
68
how to detect recent Streptococcus pyogenes infection
ASO titer
| pyrrolidonyl arylamidase +
69
Streptococcus pyogenes - exotixins
1. exotoxin A
2. Streptolysin O
3. erythrogenic toxin
70
Streptococcus pyogenes - M antibodies
enchance host defence againste S. pyogenes
| can give rise to rheumatic fever
71
Streptococcus pyogenes - M antibodies can give rise to
rheumatic fever
72
Pyrrolidonyl Arylamidase (PYR) test is / + in
a rapid test which is used for the presumptive identification of group A beta-hemolytic Streptococci adn entercocci
73
Major criteria for acute rheumatic fever
1. polyarthritis
2. carditis
3. subcutaneous nodules
4. erythema marginatum
5. Sydenham chorea
74
streptococcal pharyngitis can result in
| streptococcal impetigo can result in
Pharyngitis: 1. rheumatic fever 2. glomerulonephritis
Impetigo: glomerulonephritis
75
glomerulonephritis is preceded by
streptococcal pharyngitis or impetigo
| MORE COMMONLY IMPETIGO
76
Streptococcus agalactiae - characteristics
group (-), group B, Bacitracin resistant, β- hemolytic
77
Streptococcus agalactiae colonizes
vagina
78
Streptococcus agalactiae causes
1. pneumonia
2. Meningitis
3. Sepsis
MAINLY IN BABIES
79
test to detect Streptococcus pyogenes
Pyrrolidonyl Arylamidase (PYR) test
80
test to detect Streptococcus agalactiae
1. Hippurate test
2. CAMP test
3. PYR -
81
Streptococcus agalactiae - CAMP test
CAMP factor enlarges the area of hemolysis by S. aureus
82
Screen pregnant women for Streptococcus agalactiae at
35-37 weeks of gestation
83
patients with + culture of Streptococcus agalactiae -->
receive intrapartum penicillin for prophylaxis
84
Enterococci - bugs and characteristics
E. faecalis
E. faecium
gram +, cat -, Group D, growth in bile and 6.5% NaCL
α or γ hemolysis
85
Enterococci - area of the body
normal flora of the colon
86
Enterococci are resistant to / test to detect
penicillin G
| PYR +
87
Enterococci can cause
I. UTI
2. biliary tract infection
3. sabacute endocarditis
(following GI/GU procedures)
88
Enterococci can cause UTI, biliary tract infection and sabacute endocarditis following
GI/GU procedures
89
group D streptococci - bugs (and characteristics)
1. enterococcus (E. faecalis, E. feacium) - Group D, growth in bile and 6.5% NaCL, γ hemolytic
2. Nonenterococcus (Streptococcus bovis) - Group D, Growth in bile, not in 6.5 NaCL, γ hemolytic
90
Lancefield grouping is based on
differences in the C carbohydrate on the bacterial cell wall
91
VRE are important cause of (and means)
nosocomial infection (Vancomycin-resistant enterococci)
92
Streptococcus bovis - clonizes the
gut
93
Streptococcus bovis biotype 1
Streptococcus gallolyticus
94
Streptococcus gallolyticus (Streptococcus bovis biotype 1) can cause
bacteremia and sabacute endocarditis and is associated with colon cancer
95
Streptococcus gallolyticus (Streptococcus bovis biotype 1) can cause bacteremia and sabacute endocarditis and is associated with
colon cancer (or polyps)
96
Corynobacterium diptheria causes diptheria via exotoxin encoded by
β-prophage
97
Diptheria toxin - mechanism of action
ADP-ribosilation of E2F --> INACTIVATION OF E2F ELONGATION --> inhibition of tRNA translocation --> inhibition of protein synthesis
98
diptheria - symptoms
1. pseudomembranous pharyngitis (grayish-white membrane)
2. Lymphadenopathy (bull neck)
3. myocaridits
4. arrhythmia
5. demyelination/paralysis of peripheral nerves
99
diptheria prevention?
toxoid vaccine
100
Corynobacterium diptheriae - lab diagnosis
1. gram + rob with metachromatic (blue and red) granules
2. Elek test for toxin
3. Black colonies on cystein-tellurite agar
101
test for diptheria toxin
Elek test
102
Special culture requirements - Corynebacterium diphtheriae - media ?
Tellurite agar and Loffler medium
103
Corynobacterium diptheriae - granules
metachromatic (blue and red)
104
spores - bacteria - (when)
some bacteria can form spores at the end of the stationary state when nutrients are limited
105
bacterial spore - characteristics / chemical composition
resistant to dehydration, heat and chemicals
chemical composotion: 1. keratin like - coat
2. dipicolinic acid
3. peptidoglycan
106
how to kill spores
must autoclave to potentially kill spores (as done in surgical equipment) by steaming at 121c for 15 minutes
107
spore forming bacteria - bacteria groups
1. Bacillus
2. Closturidium
3. Coxiella burnetti
108
spore forming bacteria - bugs and diseases
1. Bacillus antrhacis --> antrax
2. Bacillus cereus --> Food poisoning
3. Clostiridium botulinum --> botulism
4. Clostiridium difficile --> Antibiotic associated colitis
5. Clostiridium perfingess --> gas gangrene, food poisoning
6. Clostiridium tetani --> tetanus
6. Coxiella burnetii --> Q fever
109
Clostiridia - characteristics
gram +, spore forming, anaerobe
110
Clostiridia - bugs and characteristics
gram +, spore forming, obligate anaerobe
1. Clostiridium tetani
2. Clostiridium botulinum
3. Clostiridium perfringens
4. Clostiridium difficile
111
Clostiridia - toxins
1. Clostiridium tetani --> tetanospasmin
2. Clostiridium botulinum --> Botulinum toxin
3. Clostiridium perfringens --> Alpha toxin, head labile enterotoxin
4. Clostiridium difficile --> Toxin A (eneterotoxin), Toxin B (cytotoxin)
112
tetanospasmin blocks release of ...(from)
inhibitory neurotransmitters, GABA and glycine, from Renshaw cells in spinal cord
113
tetanospasmin - manifestations
1. spasticity
2. risus sardonicus (raised eyebrows and open grin)
3. Lockjaw (trismus)
114
tetanus is
tetanic paralysis
115
C. tetani - therapy / prevention
Prevent with tetanus vaccine
| treat with antitoxin +/- vaccine booster and diazepam (for muscle spasms) and wound debridement
116
Botulinum toxin inhibit the releiase of ....(where)
ACh at neuromuscular junction (causing botulism)
117
botulism treatment
antitoxin
118
Botiulism is caused by ....
adults: ingestion of preformed toxin
babies: ingestion of spores in honey (floopy baby syndrome)
119
botulism vs tetanus according paralysis
botulism --> flaccid paralysis
| tetanus --> spastic paralysis
120
classic symptoms of botulism
flaccid paralysis, including diplopia, ptosis, dysphagia, symmetric, descending motor paralysis, death due to respiratry failure
121
MC form of botulism in USA
| botulism - death due to
- floopy baby syndrome
| - respiratory failure
122
Clostiridium perfringens toxin and its mechanism of action
Alpha toxin: Phospholipase (lecithinase) that degrades tissue and cell membranes
enterotixin --> food poisoning
123
Clostiridium perfringens - manifestations
A. lalpha TOXIN: 1. myonecrosis (gas gangrene) 2. hemolysis (double zone of hemolyisis on blood agar)
B. spores can survie in undercooked food --> ingested, bacteria can release heat labile enetrotoxin --> food poisoning
124
Clostiridium perfringens - food poisoning
spores can survie in undercooked food --> ingested, bacteria can release heat labile enetrotoxin --> food poisoning
125
Clostiridium difficile - toxins and their action
1. Toxin A (eneterotoxin) --> binds to the brush borders of the gut --> diarrhea
2. Toxin B (cytotoxin) --> causes cytoskeletal disruption via actin depolymerization --> pseudomembranous colitis --> diarrhea
126
pseudomembranous colitis - appearance on endoscopy
yellow membrane
127
pseudomembranous colitis is often secondary to
antibiotic use, especially clidamycin or ampicillin
| associated with PPI use
128
pseudomembranous colitis - diagnosis
detection of one or both toxins in stool by PCR
129
pseudomembranous colitis - treatment
metronidazole or oral vancomycin
| For recurrent cases, consider repeating prior regimen, fidaxomicin, or fecal microbiota transplant
130
Bacillus anthracis - characteristics
gram +, spore forming, aerobe
131
Bacillus anthracis produce
edema toxin (anthrax toxin)
132
edema toxin - mechanism of action and manifestation
mimics the adenylate cyclase enzyme --> increases cAMP --> likely responsible for characteristic edematous borders of black eschar in cutaneous antrhax
133
Bacillus anthracis - unique structural characteristic
The only bacterium with a polypeptide capsule (contains D-glutamate)
134
Bacillus anthracis causes
Antrhax (cutaneous and pulmonary)
135
cutaneous antrhax?
painless, papule surrounded by vesicle --> ulcer with black eschar, (painless, pencrotic) --> uncommonly progress to bactremia and death
136
pulmonary antrhax? / aka?
inhalation of spores --> flu like symptoms that rapidly progress to fever, pulmonary hemorrhage, mediastinitis and shock. aka: woolsorter's disease
137
Bacillus - bugs?
1. Bacillus anthracis
| 2. Bacillus cereus
138
Bacillus cereus causes
foot poisoning (reheated rice syndrome)
139
Bacillus cereus poisoning - mechanism
Keeping rice warm results in germination of spores and enterotoxin formation
140
Bacillus cereus - types (and causes)
1. emetic type (preoformed heat-labile toxin, cereulide, same mechanism as cholera toxin): nausea and vomiting within 1-5 h
2. diarrheal type (heat stable toxin): watery, nonbloody diarrhea and GI pain within 8-18
141
Bacillus cereus - emetic type usually seen with
pasta and rice
142
Bacillus cereus - emetic type is caused by
cereulide, a preformed toxin
143
Bacillus cereus food poisoning - course
emetic type --> nausea and vomiting within 1-5 hrs
| Diarrheal type --> watery and, nonblody diarrhea and GI pain within 8-18 hrs
144
Listeria monocytogenes - characteristics
gram (+) rob, no spore forming, tumbling motile, faculty intracellular
145
Listeria monocytogenes - intra- or extracelullar
faculty intracellular
146
Listeria monocytogenes - acquired by
1. ingestion of unpasteurized dairy products
2. ingestion of cold deli meats
3. tranplacental transmission
4. vaginal transmission
147
Listeria monocytogenes is the only gram (+) that
produce endotoxin
148
Listeria monocytogenes - mechanism of action
Forms rocket tails (via actin polymerization) that allow intracellular movement and cell-to-cell spread accross cell membranes, thereby avoiding antibody --> characteristic tumbling motility in broth
149
Listeria monocytogenes can cause
1. in pregnant --> amnionitis, septicemia, spontaneous abortion
2. newborns --> granulomatosis infantiseptica, neonatal meningitis
3. immunocompromised patients --> meningitis
4. healthy individuals --> mild gastroenteritis
150
Listeria monocytogenes - treatment
1. gastroenteritis is self limited
| 2. ampicillin in infants, immunocompromised, and the elderly as empirical treatment of meningitis
151
bacteria resembling fungi - bags and characteristics
1. Actinomyces - anaerobe, not acid fast, GRAM +
| 2. Nocardia - aerobe, acid fast, GRAM +
152
actinomyces vs Nocardia according to location
Acinomyces --> normal oral, reproductive, and GI flora
| Nocardia --> found in soil
153
actinomyces vs Nocardia according to treatment
MNEMONIC: SNAP --> Sulfa - Nocardia / Actinom - Penicillin
Acinomyces --> penicillin
Nocardia --> sulfonamides
154
actinomyces vs Nocardia according to clinical manifestations
Acinomyces --> oral/facial abscess that drain through sinus tracts, PID with intrauterine device
Nocardia --> pulmonary infections in immunocompromised and cutaneous infection after trauma in immunocompoment
155
actinomyces vs Nocardia according to pigmented
Actinomyces israelli - yellow sulfur granules which are composed of filaments of bacteria
