Unit IV Flashcards
1
Q
What is the bacterial equivalent of tubulin?
A
FtsZ
2
Q
What is the bacterial equivalent of actin?
A
MreB
3
Q
What is the bacterial equivalent of intermediate filament?
A
CresS
4
Q
What is glycocalyx used for?
A
formation of microbial biofilms
5
Q
What molecules attaches the outer membrane of gram negative bacteria to peptidoglycan?
A
Lipoproteins
6
Q
What is another word for lipopolysaccharides?
A
Endotoxin
7
Q
What are the three components of LPS?
A
Lipid A (the toxic component) core polysaccharide O antigen that functions as a somatic antigen
8
Q
What is the classification of enteric bacteria based on their flagella?
A
H antigens
9
Q
What is a bacteriophage?
A
virus that infects bacteria
10
Q
What are heterotrophic bacteria?
A
Require organic carbon for survival
11
Q
What are autotrophic bacteria?
A
bacteria that obtain their carbon exclusively from CO2
12
Q
What are obligate intracellular bacteria? t
A
Bacteria that can grow within eukaryotic cells but
cannot be cultivated on artificial media.
13
Q
How do heterotrophic bacteria obtain both energy and
reducing power?
A
fermentation or respiration
14
Q
β-lactams
A
inhibit the final transpeptidation reaction in cross-linking of peptidoglycan.
ex: penicillin, cepalosporins
15
Q
What is the role of vancomycin?
A
inhibits utilization of lipid-linked intermediate at an
intermediate step in peptidoglycan synsthesis, e.g., elongation of the peptidoglycan chain.
16
Q
cycloserine
A
inhibits alanine racemase, preventing formation of
muramyl pentapeptide, an early intermediate in peptidoglycan synthesis.
17
Q
Polymyxins
A
cationic surfactants that disrupt bacterial outer and cytoplasmic membranes. They are less active on mammalian cell membranes.
18
Q
Aminoglycosides
A
bind to specific target proteins in the 30S ribosomal subunit and inhibit protein synthesis.
19
Q
Tetracyclines
A
reversibly bind to the 30S ribosomal subunit and inhibit
binding of aminoacyl tRNA.
20
Q
chloramphenicol
A
binds reversibly to the 50S ribosomal subunit and inhibits peptidyl transferase and peptide bond formation.
21
Q
Macrolides
A
bind to the 23S ribosomal RNA of the 50S subunit and inhibit peptidyl transferase.
22
Q
Quinolones
A
inhibit DNA gyrase and topoisomerase and interfere with DNA replication
23
Q
Rifampicin
A
inhibits RNA polymerase and interferes with the
initiation of transcription.
24
Q
Sulfonamides
A
structural analogs of p-aminobenzoic acid (PABA), which is a component of folic acid. Sulfonamides inhibit the formation of folic acid by competing
with PABA, and this in turn prevents nucleic acid synthesis.
**humans don’t make folic acid, we get it from bacteria in our gut
25
Trimethoprim
interferes with folate metabolism by inhibiting
the enzyme dihydrofolate reductase. Since both bacterial and host cells both possess this enzyme, the basis of selective toxicity lies in the 50,000-fold greater sensitivity of the bacterial enzyme to this drug.
26
Isoniazid
inhibits lipid synthesis (probably mycolic acid synthesis) in
susceptible Mycobacteria.
27
Metronidazole
appears to specifically interfere with anaerobic metabolism.
28
virulence genes are often expressed under what conditions?
low iron conditions that are encountered IN the host
29
How does Salmonella typhimurium generate genetic diversity?
It has an invertible segment of DNA which includes the promoter region of H2. When reversed the H2 promoter is expressed and H2 is made. H1 is blocked .
30
How does Neisseria gonorrhoeae generate genetic diversity?
Recombinational exchange between the expressed and a nonexpressed copy of the pilin genes results in a new pilin gene at the expression site and production of a new antigenically distinct pili on the cell surface.
**Phase Variation
31
What are examples of mutations that are of medical importance?
i) increased resistance to antimicrobials in Pseudomonas and Mycobacterium tuberculosis
ii) Streptococcus pyogenes strains with an increased
likelihood of causing invasive disease due to a single amino acid change in pyogenic exotoxin B.
32
What is fermentation?
the catabolic process in which organic compounds serve as both electron donor and electron acceptor
33
What is respiration?
need a terminal electron acceptor typically O2
34
What are the two forms of energy currency for bacteria?
1. ATP - biosynthetic interconversions
| 2. Proton Motor Force - flagellar rotation, membrane transport
35
How do you convert ATP into PMF?
ATPase
36
What is the active component in transformation?
naked DNA, probably DNA from lysing cells
37
explain transformation
crude extracts, and ultimately pure DNA, taken from virulent, encapsulated strains of the pneumococcus (S forms) could convert avirulent, nonencapsulated strains (R form) to the virulent phenotype.
38
How are some bacteria induced to become "competent" to transformation?
calcium chloride and low temperatures
39
What is transduction?
gene transfer mediated by a bacteriophage
40
what is a lysogenic response?
the host cell remains viable and the infecting phage DNA is maintained by the host cell in a noninfectious state called a "prophage"
41
What is a prophage?
phage DNA which is linearly inserted into the host cell genome where it becomes passively replicated as part of the bacterial chromosome.
42
How is the lysogenic stage maintained?
by repressor proteins that blocks expression of the
| phage genes necessary for viral DNA replication and lytic development.
43
What is bacteriophage conversion (lysogenic conversion)?
the genes controlling the new phenotypic trait are found only as a component of the phage genome; that is, the converting genes are not found alone as normal constituents of the bacterial genome.
44
What is generalized transduction?
caused by error in DNA packaging where that phage mistakenly packages bacterial DNA instead of viral DNA. It can still attach to other bacterial cells and inject this DNA to cause recombination with homologous segments
45
What is bacterial conjugation mediated by?
bacterial plasmids
46
What often encode antibiotic resistance and virulence factors?
plasmids
47
What type of plasmids are self transmissible?
conjugative plasmids
48
The mechanism of antibiotic resistance transfer is particularly prevalent among which type of bacteria?
gram positive bacteria
49
The F plasmid contains genetic information encoding what traits?
i. Autonomous replication of the plasmid DNA
ii. Synthesis of sex pili (F pili) which are essential for mediating pair formation between donor and recipient cells
iii. Conjugative transfer of F DNA to recipient (F- ) cells
iv. Ability to integrate into the bacterial chromosome
50
What is bacterial conjugation?
a form of genetic transfer that is dependent upon physical
| contact between the donor and recipient cells, and is usually mediated by certain types of bacterial plasmids
51
What are spores?
specialized cells that are produced by certain bacteria, such as Clostridium sp. and Bacillus sp.,
when the nutritional supply of carbon, nitrogen or phosphorus is limited
52
Define peritrichous?
Bacterial that have flagellar all around them
53
What are the three most common organisms responsible for infective bacterial endocarditis?
Staphylococcus aureus
Streptococci of the viridans group
coagulase negative Staphylococci **staphylcocci epidermidis
54
What bacteria is catalase positive?
staphylcocci
55
Which bacteria is catalase negative?
streptococci
56
Which bacteria is coagulase positive?
staphylcoccus aureus
57
What is an alternative name for staphylcocci epidermidis?
staph species, NOT aureus (SSNA)
| coagulase negative staphylcoccus (CNS)
58
What bacteria is the causative agent of common
| “strep throat"?
streptococcus pyogenes
59
How does streptococcus pyogenes avoid phagocytosis?
They are surrounded with M protein
60
Describe the distinct features of group a streptococcal lesions
The typical lesion is that of a SPREADING infection of the cutaneous and subcutaneous tissues (cellulitis). [Contrast with typical S. aureus infections-which are more prone to produce focal abscesses, which may be accompanied by a surrounding cellulitis]
61
What are Post-streptococcal diseases?
Glomerulonephritis- Streptococcal antigen-antibody complexes are deposited in the kidney and accumulate at the basement membrane.
Rheumatic fever- antibodies recognizing and binding to
specific host antigens of the myocardium and heart valves.. This leads to progressive antibody-mediated damage to these tissues.
62
What are the "big three pathogens" for antibiotic use?
MRSA, pseudomonas, and anaerobes
63
Which enzyme cross links peptidoglycan?
Penicillin Binding Proteins
64
What reactions are driven by penicillin binding proteins?
transpeptidase and transglycosylase
65
How do beta lactam antibiotics work?
they irreversibly bind and inactivate the transpeptidase reaction of penicillin binding proteins therefore, INHIBITS cross linking and synthesis of peptidoglycans
66
How do bacteria become resistant to beta lactam?
They produce beta lactamase which destroys the beta lactam - MODIFYING THE DRUG
Produce altered penicillin binding proteins so that the beta lactam no longer can bind - MODIFYING THE TARGET
PREVENTING DRUG TARGET INTERACTION - modifying porin channel and drug efflux mechanisms so beta lactam cannot reach its target
67
Where can beta lactamase be found?
in gram positive and gram negative bacteria
68
Is beta lactamase more commonly found in gram positive or gram negative bacteria?
Gram negative
69
How are beta lactamases encoded?
chromosomal or transferable genes
70
Narrow-spectrum β-lactamases are resistant to what type of antibiotics?
penicillins-type antibiotics (penicillin, amoxicillin, ampicillin and possibly piperacilllin)
71
Narrow-spectrum β-lactamases bacteria are sensitive to what drugs?
cephalosporins or carbapenems
72
extended spectrum beta-lactamases are notable for their resistance to what drugs?
cephalosporins
**can still be treated with beta lactamase inhibitors
73
Where are extended spectrum beta-lactamases found?
plasmids
74
What type of bacteria are beta lactamases?
gram negative
75
What are notable features of ampC-encoded β-lactamase?
it is chromosomally located
can hydrolyze penicillins, 1st 2nd and 3rd generation cephalosporins
NOT inhibited by beta-lactamase inhibitors
76
Which bacterias have ampC-encoded β-lactamase?
gram negative bacteria: enterobacter and pseudomonas
77
What are lipopolysaccarides an example of?
Pathogen associated molecular pattern (PAMP)
78
How are lipopolysaccarides recognized?
via the innate immune system -CD14 and TLR4
79
What are hemolysins?
erythrocyte membrane damaging toxins that kill target cells
80
cytolysins?
general terms for membrane damaging toxins that kill target cells.
Form pores that cause the lysis of cells
81
What are the most potent T cell activators?
superantigens
82
How does pseudomonas aeruginosa inhibit protein synthesis?
exotoxin A inactivates elongation factor 2 (EF-2) which is required for peptide chain elongation.
83
What are examples of ribosyltransferases?
Diphtheria toxin and pseudomonas aeruginosa exotoxin A both inactivate EF-2
84
How do shiga toxins of shigella and e.coli work?
they are RNA N-glycosidases that remove an adenine residue, inactivating the ribosomes
85
How does diphtheria toxins damage cells?
inhibits protein synthesis by inactivating EF-2
86
Where is the diphtheria organism found?
upper respiratory tract
87
Where do diphtheria toxins travel to?
heart, kidneys, and peripheral nerves
88
Where does pseudomonas aeruginosa exotoxin A act?
on liver cells
89
How does enterotoxin from cholerae and E.coli increase adenylate cyclase?
activates the stimulatory Gs regulatory protein
90
How does pertussis toxin increase adenylate cyclase activity?
inhibits the Gi (inhibitory) regulatory protein of the cyclase complex.
91
What are the two type of toxins produced by anthrax?
edema factor - increases cAMP
| lethal factor - cleaves MAP kinase kinase proteins and inactivates their function
92
What does edema factor need for enzymatic activity?
calmodulin and calcium
93
which toxins are zinc dependent endopeptidases?
botulinum and tetanus toxin
94
What type of bacteria uses type III secretions?
gram - bacteria
shigella
**needle insertion technique
95
What is unique about type VI secretions?
can inject effectors into bacteria and eukaryotic cells
96
Bacteria in the stationary phase are less susceptible to what drugs?
Beta lactams because there is a decrease in rate of growth and cell division. Therefore not a lot of peptidoglycan cross linking
97
What bacterial structure is targeted by quinolone?
DNA Gyrase and topoisomerase
98
What is the role of coagulase in the context of spread of infection?
Promotes the deposition of fibrin and walls off S. aureus
99
What are the bacterial components or structures that are most commonly involved in mediating adherence of bacteria to human cells?
pili
100
What bacteria uses m protein as its primary virulence factor?
streptococcus pyogenes (Group A strep)
a surface exposed protein thatninhibits phagocytosis and killing by PMNs, and enhances adherence to epithelial cells
101
MacConkeys plate grows what type of bacteria?
Gram negative
102
Which bacteria ferment lactose?
E. coli and Klebsiella pneumoniae
103
What is a bactericidal agent?
kills the bacteria
104
What is a bacteriostatic agent?
prevents the bacteria from GROWING
105
Key differences between bactericidal vs bacteriostatic agent?
Bactericidal:
used to treat SEVERE infections
acts more QUICKLY
can compensate for patients immunocompromised
used to treat bugs that are not accessible by the immune system
106
drug that is taken with food..
drug is stable in gastric acid but can be irritating to stomach (take with food)
107
What process explains the ability of N. gonorrhoeae to express different antigenic forms of pili?
genetic recombination
108
What type of bacteria is Klebsiella pneumoniae?
Gram negative rod
109
What part of LPS is the toxigenic portion?
the inner portion that has phosphorylated sugars attached to multiple fatty acids
called Lipid A
110
What is the outer portions of LPS?
The outer oligosaccharide polymer has the O chain that is used for recognition by host antibodies.
111
What bacteria produces toxins that transfer glucose from UDP-glucose to Rho family GTPases, altering the cytoskeleton of enterocytes?
Clostridium difficile
112
Which bacteria is a gram-negative rod with intrinsic resistance to penicillin, ceftriaxone (3rd gen cephalosporin) and erythromycin
pseudomonas aeruginosa
113
How would enterococci appear on gram stain?
gram positive cocci in chains
114
What is the gram stain for bacterioides fragilis?
gram negative bacillus
115
What organisms would most likely Gram stain as Gram-negative diplococci?
neisseria gonorrhea
116
Where in the body does clinamycin have good distribution
Bone for osteomylitis
117
Where in the body does tetracylcins have good distribution?
gingival gums and sebum glands
118
Where in the body do macrolides have good distributions?
in the lungs (pneumonia)
119
What drug has rapid excretion in the kidneys and is good for UTIs?
Nitrofurantoin
120
What drug has toxicity in developing bones and teeth/ causes discoloration in teeth?
tetracyclines?
121
What drug has ototoxicity and renal toxicity?
aminoglycocides
122
What is a narrow spectrum drug?
effective against gram positive or gram negative
123
What is an extended spectrum drug?
effective against gram positive AND gram negative
124
What is a broad spectrum drug?
effective against gram positive, gram negative, and atypical organisms
125
What are the broad spectrum drugs?
macrolides: inhibits 50s
chloarmphenicol: inhibits 50s
tetracyclines: inhibits aminoacetyl t-RNA
fluorquinolones (Moxi)
sulfonamides
trimethoprim
126
What are the extended spectrum drugs?
extended spectrum penicillins
cephalosporins
fluorquinolones (Cip, Levo)
Carbapenems
127
What are the narrow spectrum drugs?
```
aminoglycosides
penicillinase resistant penicillins
clindamycin (Gemi)
Vancomycin
Metronidazole
Penicillin G, V
```
128
What drug increases hepatic metabolism of other drugs?
Rifampin is an inducers of p450
129
What drug has drug drug interactions with alcohol?
metronidazole
130
The persistent suppression of bacterial growth that may occur after limited exposure to some antibacterial drugs:
post-antibiotic effects
131
What drugs exhibit concentration dependent killing?
aminoglycosides and fluroquinolones
132
What drugs exhibit time dependent killing
Beta lactams
vancomycins
macrolides
133
What drugs exhibit post antibiotic effects?
aminoglycosides and fluorquinolones
134
What are key differences between narrow and broad spectrum drugs?
narrow is more effective
broad spectrum you are more likely to cause a superinfection because you kill the health bacteria
135
Is amoxicillin or ampicillin better aborbed?
amoxicilling because it has a hydroxyl group
136
What drugs affect stage 1 in bacterial cell wall synthesis?
cycloserines (early intermediate of peptidoglycan synthesis) and fosfomycin
137
What drugs affect stage 2 in bacterial cell wall synthesis?
vancomycin (lipid linked intermediate step of peptidoglycan elongation) and bacitracin
138
What drugs affect stage 3 in bacterial cell wall synthesis?
peptidoglycan cross linking - PENCILLINS AND CEPHALOSPORINS
139
Are penicillins bactericidal or static?
bactericidal --> causes cell to lyse
140
What is the role of penicillinases and cephalopsorinases?
bacterial resistance to beta lactams that hydrolyze beta lactams
141
How is penicillin resistance acquired?
via plasmid - transduction
**staphylococcus
142
How is pencillin best absorbed?
without stomach acid therefore on an EMPTY STOMACH
poor penetration into tissues
143
Described distribution of penicillin
can enter inflamed tissue or membranes
144
How is penicillin excreted?
renal and can be excreted via breast milk
145
What is the prototypical penicillin?
penicillin G
146
What penicillin is acid resistant?
penicillin V
147
which penicillins are penicillinase resistant?
dicloxacillin, oxacillin and nafcillin *only use when penicillnase producing organisms. If not use the G spot baby (penicillin G)
148
How do extended spectrum penicillins work?
they increase hydrophilicity allowing penetration through porins of GRAM NEGATIVE ORGANISMS
149
What are the extended spectrum penicillins?
ampicillin and amoxicillin (better absorption because hydroxyl group)
**not resistant to penicillinas
150
Which penicillins can be used against pseudomonas, enterococci, and bacteroides fragilis?
ticarcillin and piperacillin
151
What are the beta lactamase inhibitors?
clavulanic acid, sulbactam, and tazobactam
152
What is augmentin?
clavulanic acid combined with amoxicillin
153
What is timentin?
ticarcillin combined with clavulanic acid
154
What is Unasyn?
sulbactam with ampicillin
155
What is Zosyn?
tazobactam with piperacillin
156
What is the primary mechanism of antibacterial action of penicillins involves:
reactions involving transpeptidation
157
What can you use to treat MRSA?
vancomycin, 5th generation cephalosporins, tetracyclins, and clindamycin
158
What drug is not broken down by beta lactamases?
cephalosporins
works well for MSSA
159
Which penicillins are IV only?
piperacillin and ticarcillin (good against pseudomonas, enteroccoci, and bacteroides fragilis)
160
Between penicillin V and G which one is prescribe outpatient vs in the hospital?
Penicillin G - IV only in hospital
| Penicillin V - oral intake/outpatient
161
Ampicillin is most effective against what bug?
Listeria monocytogene
162
what is the incidence of diarrhea with penicillins from greatest to lowest?
amoxicillin-clavulanate > ampicillin> amoxicillin > pen V
ampicillin>amoxicillin due to poorer oral absorption
163
How is vancomycin administered?
IV
164
if a patient has a GI infection would you use vancomycin or metronidazole
metronidazole is the preferred
this is the only time you would give vancomycin orally if you were to
165
Are cephalosporins extended or broad spectrum?
extended spectrum drug
166
What is unique about 3rd generation cephalosporins?
can penetrate into CSF
167
What are the first generation cephalosporins?
cafazolin and cephalexin
168
What is the prototype of 1st generation cephalosporins?
cefazolin
169
Which cephalosporin has greater activity against MSSA?
cefazolin/cephalexin
170
What is the third generation cephalosporin and what is it used against?
ceftriaxone good against neisseria gonorrhoeae, gram + step pneumonieae, and CNS distribution
171
How is cefazoline administered?
IV
172
How is cephalexin administered?
PO
173
Which cephalosporin is effective against MRSA?
5th generation - ceftaroline
174
Which drug should you NOT give if you have a patient with Type I anaphylaxis to pencillin?
cephalosporins
1% chance of cross reactivity
175
How would you treat meningitis?
3rd generation cephalosporin - ceftriaxon/ ceftazidime
176
What cephalosporin would you use to treat pseudomonas?
generation 3
177
How would you treat chlamydia?
macrolide or tetracyclines
178
Do you give cephalosporins to a patient with type I sensitivity to penicillin?
NO 1% CHANCE OF CROSS REACTIVITY. DO NOT TAKE RISK
179
Do cephaosporins cover most anaerobes?
YES!
180
What are the adverse reactions associated with vacomycin?
red man syndrome
ototoxicity
nephrotoxicity
181
How is penicillin G administered?
IM
182
Which bacteria alter the methylation of 50s ribosome to prevent macrolide binding?
step. pneumonia and h. influenzae
183
How does resistance against macrolides occur?
***Methylation of target site -50S ribosome MAJOR ONE
multi-dru efflux tranporter
184
Which macrolide is NOT metabolized?
Azithromycin
185
which macrolide should you use for community acquired pneumonia due to strep penumoniae that is resistant to other antibiotics?
Telithromycin
186
How should tetracyclines be administered?
on an empty stomach
187
What can impair tetracycline absorption?
Milk products - Al, Ca, Mg, Fee
188
Which tetracycline should be used for patients with renal disease?
Doxycycline (non-renally excreted)
189
What type of spectrum drug is tetracycline?
broad spectrum bacteria
190
What drug should be avoided during latter half of pregnancy and in children under 8 years of age?
tetracycline - it disrupts bone and teeth growth, also discoloration
191
How are macrolides administered?
orally
192
What is the advantage of clarithromycin over erythromycin?
Clarithromycin has greater duration of activity
better for treating H. pylori
193
How often do you give clarithromycin (biaxin)?
bi daily
194
How often do you give erythromycin?
4 times a day
195
How often do you give azythromycin?
once a day
196
What is the relationship between caffeine and macrolides?
they both inhibit the p450 pathway!
197
Which tetracycline has the best absorption?
Doxycycline
198
Which tetracycline is absorbed better and has a longer duration of action?
doxycycline - only 2 a day
199
How is clindamycin absorbed?
Orally!
200
which drug is effective against gram negative AEROBES?
aminoglycosides
201
How are aminoglycosides administered?
IM
202
What drugs need to be administered with supervision?
Vancomysin (IV)
| aminoglycosides (IM)
203
How is fluoroquinolone resistance acquired?
plasmid mediated resistance
204
How is fluorquinolone administerd?
orally
205
Is fluoroquinolone good for MRSA?
no because it does not have a beta lactamase
206
which fluorquinolone is not good for UTIs?
moxifloxacin because it does not show up in urine
207
what do you typically use fluorquinolones for?
upper respiratory and UTI infections
208
what type of bugs is moxfloxacin good for?
anaerobes
209
How can you treat pseudomonas
piperacillin/ticarcillin
aminoglycosides
ciprofloxin/levofloxin
ceftazidime (3rd C) and cefepime(4th C)
210
How are cephalosporins administered?
IM/IV
