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94 Cards in this Set
- Front
- Back
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What does MSSA stand for?
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methicillin sensitive staphylococcus aureus
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How can MSSA (non-MRSA strains) be treated?
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1.Penicillin G and V or first generation Cephalosporins 2. Beta lactam stable penicillins 3.Non-penicillins for allergic patients
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What are some Penicillin G and V or first generation Cephalosporins used to treat MSSA?
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Cefazolin and cephalothin
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What are some Beta lactam stable penicillins used to treat MSSA?
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Methicillin Oxacillin naficillin dicloxacillin
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How can penicillin allergic patients be treated for MSSA?
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Macrolides (i.e. erthromycin) and clindamycin
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What can be used to treat MRSA?
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"Vancomycin (systemic infections) or Rifampin + aminoglycosides (i.e. Gentamicin Amikacin)
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What can be used to treat wound infections?
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"Sulfamethoxasole/trimethoprim (SMX/TMP) or SMX/TMP + Rifampin and in serious cases SMX/TMP + Rifampin + Vancomycin
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What is bacitracin?
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topical antibiotic cream
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What is mupirocin used for?
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to reduce the transmission of bacteria from one person to another
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What does MRSA stand for?
|
methicillin resistance staphylococcus aureus
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Why are some bacteria resistant to penicillins?
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beta-lactamases hydrolyze the beta-lactam ring of penicillin
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How does MRSA become resistant to methicillin?
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as the result of acquisition of mecA gene that encodes for a novel penicillin-binding protein PBP2'
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Cephalosporins and Cephamycins are what type fo drugs?
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beta-lactam
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How do beta-lactams work?
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they inhibit the cross-linking of peptidoglycan
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Cephalosporins and Cephamycinsare prodcued by what fungus?
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Acremonium
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What group of antibiotics has a methoxy group at position 7 of the beta-lactam ring?
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cephamycins
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Why are cephamycins useful?
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they are highly resistant to beta-lactamases
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The beta-lactam ring is cephalosporins is more protected and is thus less susceptible however certain bacteria produce this and gain resistance
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cephalosporinase
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TRUE OR FALSE: Cephalosporins can be given to people who are allergic to penicillins.
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TRUE with some precautions and under certain conditions
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Bacitracin is toxic to humans. Why can it still be used?
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When used topically it has poor absorption
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Bacitracin is produced by?
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Bacillus subtilis and B. licheniformis
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|
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Vancomycin is produced by?
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species of Streptomyces orientalis
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Bacitracin prevents what?
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peptidoglycan synthesis
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|
|
Vancomycin prevents what?
|
formation of the peptide portion of peptidoglycan
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|
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Vancomycin is effective against what type of bacteria?
|
gram-positive (such as MRSA)
|
|
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MSSA turns into MRSA by aquiring what genetic element?
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“ staphylococcal cassette chromosome mec” (SCCmec)
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TRUE OR FALSE: There are 2 types of mec gene complex...Type I and Type II
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FALSE: there are 5 (Type I through V)
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What is the specialized carrier for methicillin resistance?
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SCCmec
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What is contained in SCCmec?
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1. mec Gene complex (mecA and its regulators) 2. ccr Gene Complex which encodes site specific recominases that give it mobility
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Health care associated MRSA has what types of SSCmec?
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I II III
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Health care associated MRSA is resistant to many antibiotics such as...
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All beta-lactams Aminoglycosides Quinolones Trim/Sulfa
|
|
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Community aquired MRSA has what types of SSCmec?
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IV or V
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TRUE OR FALSE: Community acquired MRSA is susceptible to most other non-beta lactam drugs
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TRUE
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Community acquired MRSA has what toxic genes?
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Panton-Valentine Leukocidin (PVL)
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PVL in CA-MRSA promotes what?
|
abscess formation and a fatal necrotizing pneumonia
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|
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What is the efflux mechanism?
|
mef genes encode a protein that is incorporated into the bacterial cell membrane. The protein acts as an efflux pump and removes macrolide from the bacteria but has no effect on clindamycin or streptogramin
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Efflux pump removes what?
|
macrolide
|
|
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The efflux pump does not remove what two things?
|
clindamycin and streptogramin
|
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What is methylase?
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"Methylase of a specific ribosome site is a target of modification causing resistance to Macrolides (i.e. Erythromycin)
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What is MLSB resistance?
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"Resistance to Macrolides (i.e. Erythromycin)
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What is the mechanism for macrolides?
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Binds to the 50S ribosomal subunit causing inhibition of RNA dependent protein synthesis at chain elongation step
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Binds to 50S ribosome at “P” site and inhibits intiation complex formation. There is competitive inhibition with fMET-tRNA
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What is the mechanism for clindamycin resistance?
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methylation blocks binding of clindamycin to 50S ribosome (MLSB)
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|
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Methylation causes reduced binding of
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macrolide lincosamides and type-B streptogramins (MLSB resistance)
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|
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How does VRSA get its resistance?
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Acquisition of vanA gene from Enterococcus
|
|
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How is VRSA resistance determined?
|
Vancomycin screen on BHI agar containing 6 µg/ml vancomycin
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|
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What are the values for susceptible intermediately susceptible and resistant when doing a vancomycin screening on S. aureus
|
S= less than or equal to 2 I = 4-8 R = greater than or equal to 16
|
|
|
What does MSSA stand for?
|
methicillin sensitive staphylococcus aureus
|
|
|
How can MSSA (non-MRSA strains) be treated?
|
1.Penicillin G and V or first generation Cephalosporins 2. Beta lactam stable penicillins 3.Non-penicillins for allergic patients
|
|
|
What are some Penicillin G and V or first generation Cephalosporins used to treat MSSA?
|
Cefazolin and cephalothin
|
|
|
What are some Beta lactam stable penicillins used to treat MSSA?
|
Methicillin Oxacillin naficillin dicloxacillin
|
|
|
How can penicillin allergic patients be treated for MSSA?
|
Macrolides (i.e. erthromycin) and clindamycin
|
|
|
What can be used to treat MRSA?
|
"Vancomycin (systemic infections) or Rifampin + aminoglycosides (i.e. Gentamicin Amikacin)
|
|
|
What can be used to treat wound infections?
|
"Sulfamethoxasole/trimethoprim (SMX/TMP) or SMX/TMP + Rifampin and in serious cases SMX/TMP + Rifampin + Vancomycin
|
|
|
What is bacitracin?
|
topical antibiotic cream
|
|
|
What is mupirocin used for?
|
to reduce the transmission of bacteria from one person to another
|
|
|
What does MRSA stand for?
|
methicillin resistance staphylococcus aureus
|
|
|
Why are some bacteria resistant to penicillins?
|
beta-lactamases hydrolyze the beta-lactam ring of penicillin
|
|
|
How does MRSA become resistant to methicillin?
|
as the result of acquisition of mecA gene that encodes for a novel penicillin-binding protein PBP2'
|
|
|
Cephalosporins and Cephamycins are what type fo drugs?
|
beta-lactam
|
|
|
How do beta-lactams work?
|
they inhibit the cross-linking of peptidoglycan
|
|
|
Cephalosporins and Cephamycinsare prodcued by what fungus?
|
Acremonium
|
|
|
What group of antibiotics has a methoxy group at position 7 of the beta-lactam ring?
|
cephamycins
|
|
|
Why are cephamycins useful?
|
they are highly resistant to beta-lactamases
|
|
|
The beta-lactam ring is cephalosporins is more protected and is thus less susceptible however certain bacteria produce this and gain resistance
|
cephalosporinase
|
|
|
TRUE OR FALSE: Cephalosporins can be given to people who are allergic to penicillins.
|
TRUE with some precautions and under certain conditions
|
|
|
Bacitracin is toxic to humans. Why can it still be used?
|
When used topically it has poor absorption
|
|
|
Bacitracin is produced by?
|
Bacillus subtilis and B. licheniformis
|
|
|
Vancomycin is produced by?
|
species of Streptomyces orientalis
|
|
|
Bacitracin prevents what?
|
peptidoglycan synthesis
|
|
|
Vancomycin prevents what?
|
formation of the peptide portion of peptidoglycan
|
|
|
Vancomycin is effective against what type of bacteria?
|
gram-positive (such as MRSA)
|
|
|
MSSA turns into MRSA by aquiring what genetic element?
|
“ staphylococcal cassette chromosome mec” (SCCmec)
|
|
|
TRUE OR FALSE: There are 2 types of mec gene complex...Type I and Type II
|
FALSE: there are 5 (Type I through V)
|
|
|
What is the specialized carrier for methicillin resistance?
|
SCCmec
|
|
|
What is contained in SCCmec?
|
1. mec Gene complex (mecA and its regulators) 2. ccr Gene Complex which encodes site specific recominases that give it mobility
|
|
|
Health care associated MRSA has what types of SSCmec?
|
I II III
|
|
|
Health care associated MRSA is resistant to many antibiotics such as...
|
All beta-lactams Aminoglycosides Quinolones Trim/Sulfa
|
|
|
Community aquired MRSA has what types of SSCmec?
|
IV or V
|
|
|
TRUE OR FALSE: Community acquired MRSA is susceptible to most other non-beta lactam drugs
|
TRUE
|
|
|
Community acquired MRSA has what toxic genes?
|
Panton-Valentine Leukocidin (PVL)
|
|
|
PVL in CA-MRSA promotes what?
|
abscess formation and a fatal necrotizing pneumonia
|
|
|
What is the efflux mechanism?
|
mef genes encode a protein that is incorporated into the bacterial cell membrane. The protein acts as an efflux pump and removes macrolide from the bacteria but has no effect on clindamycin or streptogramin
|
|
|
Efflux pump removes what?
|
macrolide
|
|
|
The efflux pump does not remove what two things?
|
clindamycin and streptogramin
|
|
|
What is methylase?
|
"Methylase of a specific ribosome site is a target of modification causing resistance to Macrolides (i.e. Erythromycin)
|
|
|
What is MLSB resistance?
|
"Resistance to Macrolides (i.e. Erythromycin)
|
|
|
What is the mechanism for macrolides?
|
Binds to the 50S ribosomal subunit causing inhibition of RNA dependent protein synthesis at chain elongation step
|
|
|
|
Binds to 50S ribosome at “P” site and inhibits intiation complex formation. There is competitive inhibition with fMET-tRNA
|
|
|
What is the mechanism for clindamycin resistance?
|
methylation blocks binding of clindamycin to 50S ribosome (MLSB)
|
|
|
Methylation causes reduced binding of
|
macrolide lincosamides and type-B streptogramins (MLSB resistance)
|
|
|
How does VRSA get its resistance?
|
Acquisition of vanA gene from Enterococcus
|
|
|
How is VRSA resistance determined?
|
Vancomycin screen on BHI agar containing 6 µg/ml vancomycin
|
|
|
What are the values for susceptible intermediately susceptible and resistant when doing a vancomycin screening on S. aureus
|
S= less than or equal to 2 I = 4-8 R = greater than or equal to 16
|
