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Therapeutics III > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Staphylococcus aureus

A

Gram positive cocci in clusters

Adaptive and successful because of wide range of virulence factors

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2
Q

What is methicillin resistance of staph aureus attributed to?

A

mecA gene that encodes for different penicillin binding proteins
If present switch from a penicillin to something like a vancomycin

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3
Q

2 major classes of MRSA

A

Healthcare and community associated

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4
Q

staphylococcus epidermidis

A 
Gram positive cocci in clusters
Coagulase negative staph (CoNS)
Found on skin
Not virulent or pathogenic, but can be
Multi drug resistant 
More likely to be methicillin resistant if it is a pathogen
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5
Q

What differentiates staph aureus from staph epidermidis?

A

Coagulase test

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6
Q

What infections should you consider staph epi?

A

Catheter related infections
Skin/skin infections- cellulitis
prosthetic joint infections
prosthetic valve endocarditis

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7
Q

Streptococcus pneumoniae

A

One of the most common gram positive organisms found in pairs and chains
Normal sinus colonizer in some
Virulent and pathogenic
Encapsulated- increases resistance to macrolides, beta-lactams, fluoroquinolones

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8
Q

Streptococcus commonly causes

A

**Community-acquired pneumonia
**Bacterial meningitis
Sinusitis
Otitis media
Skin/skin infections
Etc.

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9
Q

Streptococcus pyogenes

A

Gram positive cocci in pairs and chains
Group A strep (GAS)- flesh eating bacteria
Virulent and pathogenic- toxin producer, causes tissue necrosis
Still sensitive to PCN!

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10
Q

Streptococcus pyogenes commonly causes

A

Strep throat
Skin/skin structure infections
Toxic shock syndrome

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11
Q

Strep unlike staph do not produce

A

Beta lactamase- meaning they are still susceptible to many older drugs like PCN (drug of choice)

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12
Q

Streptococcus agalactiae

A

Gram positive cocci in pairs and chains
Group B strep
Normal vaginal flora in 40% of women- tested during pregnancy and treated continuously during delivery
Usually only causes infections in immunocompromised patients

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13
Q

What is the most common cause of neonatal sepsis or meningitis?

A

Streptococcus agalactiae

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14
Q

Enterococcus faecalis

A

Gram positive cocci in pairs and chains

Normal flora of GI tract, skin, and mouth

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15
Q

E. faecalis and E. faecium commonly cause

A

Nosocomial (hospital acquired) infections

-Bacteremia, endocarditis, UTI, wound infection

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16
Q

E. faecalis and E. faecium resistance

A

E. faecalis is less resistant than E. faecium

VRE is more often E. faecium

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17
Q

Neisseria sp

A

Gram negative cocci, encapsulated

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18
Q

Neisseria meningitidis

A

2nd most common pathogen in bacterial meningitis
Small % of the population are colonized with N. meningitidis in sinus cavity
Passed by exchange of saliva or respiratory secretions
Vaccine available

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19
Q

Neisseria gonorrhoeae

A

Causative agent of gonorrhea
Not normal flora
Introduced by direct mucosal surface contact during sexual interaction
Can cause neonatal infections if mother is infected

Becomong resistance to ceftriaxone and fluoroquinolones

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20
Q

Escherichia coli and Klebsiella sp.

A

Gram-negative rod
Common bacteria in GI tract
Commonly causes UTI (community and hospital associated), bacteremia, intra-abdominal, wound, healthcare-associated pneumonia

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21
Q

What is the most common bacteria in GI tract?

A

B. fragilis

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22
Q

What is the most common aerobic bacteria in GI tract?

A

E. coli

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23
Q

Which E. coli is a common cause of food-borne illnesses?

A

E. coli 0157

Non-harmful in cattle, toxic in humans

24
Q

ESBL

A

Extended spectrum beta-lactamases (ESBL) are most commonly produced by E.coli and Klebsiella sp.

25
Q

SPACE Organizms

A 
S- erratia
P- roteus
P-seudomonas
A-cinetobacter
C-itrobacter
E-nterobacter

Grouped together because they are common producers of ampC beta-lactamase (deactivates ALL beta-lactams except cefepime and carbapenems
All cause various infections in immunocompromised or hospitalized patients primarily
Many are multi-drug resistant so susceptibility testing is required
Need to have at least 1-2 drugs to cover some of them empirically until they are cultured.

26
Q

Pseudomonas aeruginosa

A

Gram-negative rod
Outside of the hospital found in soil or water
NOT normal flora
Colonization can happen in hospitalized patients (chronic ventilator pts, indwelling catheters or g-tubes)
Virulent and resistant
Common cause of healthcare-associated pneumonia (2nd leading pathogen to MRSA), bacteremia, wound infections, post-op infections, UTI

27
Q

Acinetobacter sp/

A

Gram negative rod ( can be coccoid shape in stationary phase)
Mostly found in hospitals in/on equipment
-can live for days to weeks on inanimate objects
=Ingection control is best defense
Infects immunocompromised pts
High mortality rate due to severity of illness in pts not virulence
Causes pneumonia in ventilated pts, infects open wounds, line infections (only if on ventilator, IV, open wound, etc. )

28
Q

Hemophilus influenzae

A 
Gram-negative cocco-bacillus
Encapsulated
HIB vaccine since 1985
Non B strains still cause 
Causes CAP, meningitis, sinusitis, otitis media, conjunctinitis
29
Q

Atypicals

A

Legionella pneumophila- pontiac fever, legionnairs disease, found in water and AC vents
Chlamydia pneumoniae
Mycoplasma pneumoniae (commonly causes pneumonia in healthy individuals)
Abnormal cell walls
All cause RTIs

30
Q

Treatment options for atypicals

A

fluoroquinolones (-floxacin, except ciprofloxacin which has no atypical coverage)
Macrolide (-mycin)
Tetracyclines (-cycline)

31
Q

Z-pack

A

Has activity for both strep and mycoplamsa

32
Q

Anaerobes

A

Clostridium sp.
Bacteriodes
Gram positive
Spore formers

33
Q

Clostridium botulinum

A

Associated with honey and home canned food
Produces toxin that causes paralysis
Damage is from toxin so no antibiotics
Trivalent antitocin is available from CDC

34
Q

Clostridium tetani

A

Associated with puncture wounds
Produces toxin that causes repeated synapse firing resulting in muscle spasms, hyperreflexia and seizures
Tx- penicillin, surgery, muscle relaxants
Tetanus booster q 10 y

35
Q

Clostridium perfringens

A

Gas gangrene
Produces toxins and enzymes causing tissue necrosis
Tx- antitoxin, surgery, hyperbaric chamber

36
Q

Clostridium difficile

A

CDAD (C. diffassociated diarrhea)
Abx eradicate normal flora in GIT with C. diff overgrowth, leaves spore state to replicate
Severe diarrhea, pseudomembranes, coltitis
Tx- oral metronidazole, oral vanc, oral fidoxamicin
Strict handwashing, alcohol gels are not effective

37
Q

C. diff antibiotic exposure

A

Single most important risk factor- 85% have abx exposure in past 28 days
Abx kill protective intestinal flora which causes C. diff to overgrow and produce toxins.

38
Q

Microbial transplantation and C.diff treatment

A

Fecal donation from family member delivered by colonoscopy or feeding tube
Very effective in C. diff
Also effective: treatment with spores of nontoxic C.diff strain M3

39
Q

Bacteriodes

A

Anaerobes
Bacteriodes fragilis- most common bacteria in GI tract, encapsulated
Bacteriodes melaninogenicus- found in oral cavity, can cause fusospirochetal disease (trench mouth) and advanced peridontitis

40
Q

Fusobacterium necrophorum-

A

cause of Lemierre syndrome, throat infection can lead to abscess

41
Q

5 general mechanisms of antibacterial action

A

Cell wall synthesis- bacteriocidal
Damage to cell membrane
Modification of nucleic acid/DNA synthesis
Modification of protein synthesis (at ribosomes)
-modification of energy metabolism within the cytoplasm (at folate cycle)

42
Q

General resistance mechanisms

A
  1. ) Enzymatic destruction- main method. Beta lactamase is produced at the penicillin binding protein (PBP)
  2. ) Altered target- PBP changes in such a way that thee beta lactam (Abx) can no longer bind. MRSA
  3. ) Decreased uptake- for organisms with an outer membrane. If the porin channel is changed by AA substitutions there will be decreased uptake. More common with gram negative.
  4. ) Increased efflux
43
Q

Penicillin are effective against

A

Many gram + cocci and some gram -

44
Q

Cephalosporins are effective agaisnt

A

First gen- gram +, some gram-

Second gen- more gram -, similar gram +

45
Q

Imipenem, meropenem effective against

A

Gram +, gram-, anaerobes

46
Q

Aztreonam effective against

A

Gram - only

47
Q

Vanc effective against

A

Gram + only

48
Q

Aminoglycosides effective against

A

Aerobic gram - bacilli

49
Q

Tetracyclines effective against

A

Aerobic and anaerobiv gram + and gram -, mycoplasma, chlamydia

50
Q

Erythromycin, azithromyicn, -mycin effective against

Not clindamycin

A

Gram +, mycoplasma, chlamydia, legionella

51
Q

Clindamycin effective against

A

Most gram +, many anaerobes

52
Q

Sulfonamides effective against

A

Some gram+ and gram-

53
Q

Quinolones effective against

A

Some gram + and most gram-

54
Q

Rifampin effective against

A

Gram +

55
Q

Drugs with concentration-dependent killing

A

aminoglycosides, fluoroquinolones, metronidazole, amphotericin
Peak to MIC ration >8-10, AUC to MIC ratio >125

56
Q

Drugs with time-dependent killing

A

Beta lactams, amcrolides, vanc, tetracyclines, azoles
Time above MIC >60% of dosing intervas
Vanc AUC-MIC >400 (achieve through trough)

57
Q

Post antibiotic effect

A

Even when levels dip below MIC the organism do not immediately regrow. Impacts frequency of dosing

Therapeutics III (7 decks)

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