GRAM POSITIVE Flashcards
1
Q
Gram positive bacteria that is catalase positive, coagulase positive, and causes beta hemolysis on blood agar.
A
Staphylococcus aureus
2
Q
Virulence factor of S. aureus that prevents phagocytosis
A
Polysaccharide capsule
3
Q
Virulence factor of S. aureus that inactivates penicillin derivatives.
A
Penicillinase
4
Q
Mechanism of toxic shock syndrome toxin-1 (TSST-1)
A
T cell stimulation TSST-1 binds to major histocompatibility class (MHC) class II molecules , yielding T-cell stimulation , which promotes the protein manifestations of the toxic shock syndrome.
5
Q
Bacteria causing acute endocarditis in IV Drug users.
A
Staphylococcus aureus
6
Q
Site on long bones commonly affected in osteomyelitis caused by S. aureus.
A
Metaphysis
In osteomyelitis , the primary focus of S. aureus growth is typically in a terminal blood vessel of the metaphysis of a long bone , leading to necrosis of bone and chronic suppuration.
7
Q
Mechanism of drug resistance against Vancomycin.
A
Reprogramming of D-ala-D-ala
8
Q
Organism causing endocarditis involving prosthetic heart valves.
A
Staphylococcus epidermidis
9
Q
Hemolysis pattern of the organism that produces streptokinase.
A
Beta / Complete hemolysis.
The organism is Strep. pyogenes , a beta-hemolytic streptococcus.
10
Q
Titers used to document antecedent impetigo contagiosa.
A
anti-DNAse B
11
Q
Bacillus cereus toxin that functions as a superantigen causing acute vomiting.
A
Heat stable enterotoxin
12
Q
Type of paralysis caused by Clostridium botulinum.
A
Flaccid
13
Q
Timing of appearance of symptoms of botulism after ingestion of toxic food.
A
18-24 hours
14
Q
Organisms causing birth complicated by sepsis , multiorgan abscesses, and disseminated granulomas.
A
Listeria monocytogenes
15
Q
Non-toxoid vaccines targeting common bacteria. (3)
A
- S. Pneumonia
- N. Meningitides
- H. Influenza type B
16
Q
Indicator for strep throat.
A
ASO antibody titer. Peaks at around 3-5weeks , but may remain positive for several months.
17
Q
Follow the algorithm:
Gram positive cocci , Gamma hemolytic , No growth in 6.5% NaCl.
A
NOnenterococcus: S. bovis
18
Q
Follow the algorithm:
Gram positive cocci, Gamma hemolytic , positive growth in 6.5% NaCl
A
Group D enterococcus Strep
( E. faecium, E. faecalis )
19
Q
Follow the algorithm:
Gram positive cocci, Beta hemolytic , Bacitracin sensitive
A
Streptococcus pyogenes
(Group A strep)
20
Q
Follow the algorithm:
Gram positive cocci, Beta hemolytic, Bacitracin resistant
A
Streptococcus agalactiae
(Group B strep)
21
Q
Follow the algorithm:
Gram positive cocci , Alpha hemolytic , Optochin resistant
A
Viridans streptococci
(S. mutans, etc.)
22
Q
Follow the algorithm:
Gram positive cocci, alpha hemolytic , optochin sensitive.
A
Streptococcus pneumoniae
23
Q
Follow the algorithm:
Initial test to differentiate strains of staphylococcus ?
A
Coagulase test
24
Q
Follow the algorithm :
Next test to differentiate Coagulase negative staph?
A
Novobiocin Sensitivity Test
25
Most virulent staph species?
Staphylococcus aureus
26
Primary sites of human colonization with staphylococcus aureus?
Anterior nares & Oropharynx
27
Most common cause of surgical wound infection?
Staphylococcus aureus (HPIM)
28
Most common cause of osteomyelitis over all?
Staphylococcus aureus
29
Most common cause of septic arthritis in native joints?
Staphylococcus aureus
30
Urease expression of staphylococcal epidermidis?
( positive or negative)
Positive
31
Urease expression of staphylococcal Saprophyticus?
(Positive or Negative)
Positive
32
Novobiocin sensitivity of Staphylococcus saprophyticus ?
Resistant
33
Novobiocin sensitivity of Staphylococcus epidermidis?
Sensitive
34
Toxin of Staphylococcus aureus that causes rapid-onset food poisoning?
Preformed enterotoxin
35
Hemolysis pattern of Staphylococcus aureus?
Beta hemolytic
36
Staphylococcus can turn this agar yellow.
Mannitol salt agar
37
What mutation causes **intermediate susceptibility** to vancomycin in staphylococcus aureus? (VISA)
Cell wall alterations
38
What mutation causes vancomycin **resistance** in Staphylococcus aureus? (VRSA)
VanA gene from enterococci
39
What syndrome does staphylococcus aureus exfoliative toxin cause?
Scalded Skin Syndrome / Ritter Disease
40
What layer of epidermidis is most affected by staphylococcus aureus exfoliative toxin?
Stratum granulosum
41
What does the exfoliative toxin cleave in scalded skin syndrome?
Desmosomal cadherins (desmoglein)
42
Classic cutaneous sign seen in Scalded Skin Syndrome?
Nikolsky Sign
43
What virulence factor aureus is encoded by phages and can kill white blood cells?
PVL ( Panton Valentine Leukocidin)
44
Most important virulence factor for community acquired -MRSA?
PVL ( Panton Valentine Leukocidin)
45
Toxin responsible for toxic shock syndrome?
TSST-1 ( Toxic Shock Syndrome Toxin -1)
46
What makes staphylococcus aureus resistant to penicillins?
B-lactamase production
47
What makes staphylococcus aureus resistant to nafcillin ?
Staphylococcal cassette chromosome mec (SCCmec)
48
Treatment for MRSA?
Vancomycin
49
Hemolytic pattern of Staphylococcus aureus?
Beta hemolytic
50
Causes of patchy bacterial pneumonia after viral infection?
Staphylococcus aureus
51
Most common cause of septic arthritis overall?
Staphylococcus aureus
52
Lancefield classification of Streptococcus pyogenes?
Group A
53
Lancefield category of Streptococcus agalactiae?
Group B
54
Lancefield classification of Streptococcus bovis group?
Group D
55
What streptococcus pyogenes virulence factor is the culprit behind molecular mimicry in rheumatic fever ?
M protein
56
What childhood exanthem is caused by streptococcus pyogenes?
Scarlet fever
57
What titer is more specific for a recent Streptococcus pyogenes **cutaneous** infection?
Anti-DNase B
58
Streptococcus pyogenes is bacitracin ________ ?
(Resistant/ Sensitive)
Sensitive
B- BrAs
Bacitracin: Group **B r**esistant, Group **A s**ensitive
Group B : S. agalactiae
Group A: S. Pyogenes
59
What virulence factor from group A Strep depolymerizes DNA?
Streptococcal DNAses
60
What virulence factor from group A Strep converts plasminogen to plasmin?
Streptokinase
61
Immunity to Group A Strep infections is related to antibodies against this protein.
M protein
62
The viscosity of purulent exudates seen in group A strep infections are largely due to this virulence factor.
DNAses
63
What are the three pyrogenic exotoxin of S. Pyogenes?
SpeA , SpeB, SpeC
(Spe= Sterptococcal Pyogenic Exotoxins)
64
Which virulence factor of group A strep is largely responsible for hemolysis on blood agar?
Streptolysin S
65
PSGN is most commonly preceded by infection of the ______?
Skin
66
Rheumatic fever is most commonly preceded by infection of the ________?
Respiratory Tract (Pharyngitis)
67
Is rheumatic fever associated with cutaneous streptococcal infection?
No
68
What antibiotic is Streptococcus pyogenes uniformly susceptible to?
Penicillin G
**P**yo**G**enes
69
Most virulent pathogen in streptococcus family?
Streptococcus pyogenes
70
What toxin of Streptococcus pyogenes causes necrotizing fascitis?
SpeB
71
Group B strep hydrolyzes ____________?
Sodium hippurate resulting in positive CAMP test
72
The CAMP Test that shows an increasing zone of hemolysis when group B strep is plated with ________?
S. aureus
73
What factor produced by Group B strep enlarges the area of hemolysis around S. aureus ?
CAMP factor
74
What streptococcal bacteria must be treated when found in rectovaginal cultures of pregnant women?
Streptococcus agalactiae
75
What group D streptococcus causes endocarditis and is associated with colon Cancer?
Streptococcus galloyticus /
aka Streptococcus bovis
76
Are viridans streptococci soluble in bile?
No
77
Most prevalent member of the normal microbiota of the upper respiratory tract?
Viridans streptococci
78
Subacute endocarditis often involves ____________ valves?
(Normal vs Abnormal)
Normal
79
What is the classic “shape” used to describe S. pneumonia?
Lancet shaped
80
What reaction is used to visualize the encapsulation of S. pneumonia?
Quellung reaction
81
Most important virulence factor of S. pneumonia?
Its Capsule ( prevents phagocytosis)
82
Triad of severe sequelae from S. pneumonia bacteremia from pneumonia?
Meningitis, Endocarditis, Septic Arthritis
83
Most common cause of bacterial pneumonia in general population?
S. pneumonia
84
Oxygen metabolism of enterococci?
Anaerobic
85
Can enterococci grow in 6.5% NaCl?
Yes
6.5% NaCl
Enterococcus: E. faecalis & E. faecum
Non-enterococcus : S. bovis
86
Can enterococci grow in the presence of bile?
Yes
87
The most commonly isolated enterococci species causing infections to humans?
E. faecalis and E. faecium
88
What causes resistance of enterococci to penicillins?
Altered PBPs (Penicillin Binding Proteins)
89
What change in the peptidoglycan layer structure is responsible for vancomycin resistance in Enterococcus infections?
Change pf D-ala D-ala conformation to D-ala D-lactate
90
Which enterococcus species is MORE likely to be resistant to vancomycin?
E. faecium
91
Most common form of anthrax infection?
Cutaneous anthrax
92
Only bacterium with peptide capsule?
Bacillus anthracis
93
Form of anthrax termed as “woolsorter’s disease”?
Inhalation anthrax
( inhaling spores from animal wool, hair, hide)
94
Three components of anthrax toxins?
1. Protective antigen (PA)
2. Edema factor (EF)
3. Lethal Factor (LF)
Ang protective antigen mo bind sa either Ef or Lf = effect
95
Which component of anthrax toxin forms a membrane channel?
Protective antigen
96
Which component of anthrax toxin is an adenylate cyclase?
Edema factor
97
Which component of anthrax toxin cleaves MAPK?
Lethal factor
98
What confers heat resistance in bacterial spores ?
Dipicolinic acid
99
What bacteria produces a medusa head appearance on culture medium?
Bacillus anthracis
100
Characteristic cutaneous lesion of cutaneous anthrax?
Eschar
101
Classic chest X-ray finding of inhalation anthrax?
Mediastinal widening
102
Most feared complication of inhalation anthrax?
Pulmonary hemorrhage
103
DOC in cutaneous anthrax?
Ciprofloxacin
**C**utaneous- **Cipro**
104
What food is associated with B. cereus food poisoning?
Reheated rice
105
Specific name of the enterotoxin that causes the emetic type of B. cereus food poisoning?
Cereulide
106
Oxygen requirement of Bacillus cereus?
Obligate aerobe
107
The **emetic form** of B. cereus infections is caused by what type of enterotoxin?
Heat-stable
108
The **diarrheal form** of of B. cereus infections is caused by what type of enterotoxin?
Heat-labile
109
Classic description of the morphology of C. tetani?
**Tennis** Racket appearance due to its **terminal** spore.
110
Main habitat of C. tetani?
Soil
111
What are the proteins that tetanospasmin cleaves?
SNARE proteins
112
What cells are affected by the tetanus toxins in the spinal cord?
Renshaw cells
113
Which neurotransmitters (2) are inhibited by tetanospasmin toxin?
GABA & Glycine (Inhibitory NTs)
114
What is the name of the major SNARE protein cleaved by tetanospasmin cleaved by tetanus toxin ?
Synaptobrevin (VAMP2)
115
First part of the body affected by tetanus?
Jaw ( presenting trismus / lock jaw)
116
Which three SNARE proteins are affected by C. botulinum toxins?
1. Synaptobrevin (VAMP)
2. SNAP 25
3. Syntaxin
117
Most frequent vehicle of infection in infant botulism?
Honey
118
Type of paralysis seen in botulism?
Flaccid paralysis
119
Type of paralysis seen in tetanus?
Spastic paralysis
120
Direction of paralysis in botulism?
Cranio-caudal (From head going down)
121
Initial symptom of botulism?
Visual disturbances (Diplopia and Incoordination of Eye muscles)
122
Which neurotransmitter’s release is inhibited by botulinum toxin?
Acetylcholine
123
What bacteria causes floppy baby syndrome?
Clostridium botulinum
124
What is the GI complication caused by overgrowth of C. difficile?
Pseudomembranous colitis
125
Route of transmission of pseudomembranous colitis?
Feco-oral route
126
Top culprit antibiotics for c. difficile overgrowth?
1. Ampicillin
2. 2nd & 3rd gen Cephalosporins
127
Infections with C. difficile can cause flare-ups of this GI pathology?
Ulcerative colitis
128
Which C. difficile toxin is a potent **enterotoxin?**
Toxin A
129
Which C. difficile toxin is a potent **cytotoxin?**
Toxin B
130
Most common presentation of C. difficile infection?
Non-bloody watery diarrhea
131
Most common Clostridium that produces invasive disease?
Clostridium perfringens
132
Which toxin of C. perfringens causes **platelet aggregation and microthrombi?**
Alpha toxin
133
Which toxin of C. perfringens is a lecithinase ?
Alpha Toxin
134
What conditions can C. perfringens cause?
1. Gas gangrene
2. Food poisoning
135
Most important aspect of treating gas gangrene?
Early surgical debridement
136
Characteristic motility of listeria in broth?
Tumbling motility
137
Gram positive bacteria with tumbling motility in broth?
Listeria monocytogenes
138
Gram positive bacteria that forms **active actin rocket tails?**
Listeria monocytogenes
139
Complication of disseminated Listeria infection in neonates causing pyogenic granulomas.
Granulomatosis infantiseptica
140
Which gram positive rod / bacillus is catalase - positive ?
Listeria monocytogenes
141
Two routes of transmission of Listeria?
1. Ingestion of contaminated food
2. Transplacental
142
What allows Listeria to move intra and trans-cellularly ?
Actin Rockets ( Actin Polymers)
143
Is Listeria catalase positive or negative?
Positive
144
What virulence factor promotes phagocytosis of Listeria into epithelial cells?
Internalins A and B
145
Which Gram-positive aerobic rod produce sidrophores and uses iron as an important virulence factor?
Listeria monocytogenes
146
If Listeria infection is suspected , what antibiotic must be added to a therapy regimen?
Ampicillin with or without Gentamycin
147
What gram -positive bacteria has a chinese character appearance?
Corynebacterium diphtheriae
148
What granules are seen on C. diphtheria cultures?
Metachromatic granules / Babes-Ernst or Volutin Granules
149
What test is used to detect toxigenicity of C. diptheriae cultures?
Modified Elek Test
150
What is the main mechanism of action of C. diphtheria exotoxin?
Inactivating elongation factor EF-2 via ADP ribosylation
151
What is the classical finding in C. diphtheria infections?
Gray pseudomembranes
152
What is the classic description of the neck in diphtheria infections?
Bull Neck ( Due to the marked neck edema and lymphadenopathy)
153
What is the motility of C. diphtheria?
It’s non-motile
154
Main mode of transmission of diphtheria?
Via aerosols
155
Primary virulence factor of C. diphtheria?
Diphtheria toxin
156
What are the two major systemic toxicities of diphtheria infections?
Demyelinating polyneuropathy & Myocarditis
157
Nocardia is catalase ___________? (positive / negative)
Positive
158
Actinomyces is catalase _____________? ( positive/ negative)
Negative
159
Classic granules seen in Actinomyces abscesses.
Yellow “sulfur” granules
160
Name the bacteria:
Gram positive, anaerobic, sinus tracts , yellow sulfur granules.
Actinomyces israelii
161
Is Actinomyces aerobic or anaerobic?
Anaerobic
162
Is Nocardia aerobic or anaerobic?
Aerobic
163
What bacterial infection characteristically presents with”lumpy jaw “ after jaw trauma?
Actinomyces ( Cervicofacial mycetoma)
164
What is the treatment for Nocardia spp infection?
Sulfonamides
Treatment is a SNAP:
Sulfonamides
Nocardia
Actinomyces
Penicillin
165
What is the staining pattern of Nocardia?
Gram positive & weakly acid fast
166
What is the urease expression of nocardia?
Positive
167
What is the catalase expression of nocardia?
Positive
168
What is the urease expression of Actinomyces?
Negative
169
What is the catalase expression of Actinomyces?
Negative
170
Gas gangrene is associated with what organism?
Clostridium perfringens
171
Natural history of botulism
Previously healthy patient , usually ate canned foods several hours prior. Started with blurring of vision, difficulty swallowing, slurring of speech, progressive general weakening of upper and lower extremities, respiratory compromise, cardiac arrest.
172
Sore throat, fever, inflamed tonsils , bilateral cervical lymph nodes , no white lesions on tongue or pharynx.
Strep throat S. Pyogenes (black/ gray lesions)
173
Coagulase test is used to differentiate..
Staph aureus from other staphylococci
174
Fibrinous pericarditis in a consequence of what disease?
Autoimmune disease like SLE & Rheumatic Fever
175
Antigenic structure in S. pyogenes that plays a role in rheumatic fever?
M protein
176
Pathogenic corynebacterium vs Normal flora diphtheroids.
Diphthamide
177
Clinical features suggestive of acute rheumatic fever.
Migratory arthritis where in leg joints typically being involved first.
178
Epidemiological factors increasing the risk of acute rheumatic fever? (3)
1. Lack of access to healthcare
2. Lower standards of living
3. Poor oral hygiene
179
Characteristics of rheumatic fever. (3)
1. RF has the tendency to be reactivated by recurrent strep infection
2. RF may be associated with cutaneous streptococcal infections
3. RF is the most important cause of heart disease in young people in developing countries
180
Most useful diagnostic examination to identify organism in septic arthritis.
Culture & Sensitivity
181
True about staph aureus.
Methicillin, the commonly used antibiotic against it.
182
Most common strep that causes acute & subacute endocarditis?
S. viridans
( V for <3 shape)
183
Organs of predilection in S. aureus septicemia. (3)
1. Endocarditis
2. Osteomyelitis
3. Meningitis
184
Streptokinase is produced by ________?
S. pyogenes
185
ECG finding indicative of pericarditis.
ST segment elevation
186
Endocarditis infecting normal heart valves.
S. aureus
187
Virulence factor of S. pyogenes. (3)
1. Beta hemolysin
2. Polysaccharide
3. M protein
188
Characteristic of C. diphtheria. (3)
1. Gram positive, non-spore forming
2. Club shaped rods with metachromatic granules with aniline dyes
3. One colony, var gravis, is non-hemolytic and large
189
Diphtheria is an example of _________?
Toxemia
190
True about diphtheria vaccine.
It is only available in combination with other vaccines (TDaP)
191
Patient who accidentally stepped their foot on a rusted nail along a construction site, then developed spasticity of his muscles on his right foot and leg and developed a locked jaw. What is the diagnosis?
Tetanus
192
True about tetanus toxin?
1. Toxin causes blocking of GABA & Glycine
2. Blocks motor neurons
3. Digests protein required by neurotransmitters
193
Other diagnostic tests for tetanus.
Anaerobic culture of the contaminated tissue.
194
Streptococcal evidences of infection. (2)
1. Anti-Streptolysin O- antecedent pharyngitis , more often found in rheumatic individuals
2. Anti-DNAse B - antecedent skin infections
195
Disease process of diphtheria?
Involvement of heart , kidney, adrenals
196
Other technique in diagnosis of whipworm infection other than fecal smear.
Saturated brine flotation technique
197
Major virulence factor of S. pyogenes.
M protein
198
Progressive general weakness (symmetric on bbilateral upper and lower extremities) , sudden diplopia, dysphagia, slurred speech. Afebrile, Respiratory distress , Cardiac arrest, death. Ingestion of leftover canned sardines. What’s the diagnosis?
Botulism
199
Toxic shock syndrome. (3)
1. TSST 1 super antigen
2. Staph aureus
3. Cytokine release
