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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
SPACE Organizms
``` 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
Pseudomonas aeruginosa
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
Acinetobacter sp/
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
Hemophilus influenzae
``` Gram-negative cocco-bacillus Encapsulated HIB vaccine since 1985 Non B strains still cause Causes CAP, meningitis, sinusitis, otitis media, conjunctinitis ```
29
Atypicals
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
Treatment options for atypicals
fluoroquinolones (-floxacin, except ciprofloxacin which has no atypical coverage) Macrolide (-mycin) Tetracyclines (-cycline)
31
Z-pack
Has activity for both strep and mycoplamsa
32
Anaerobes
Clostridium sp. Bacteriodes Gram positive Spore formers
33
Clostridium botulinum
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
Clostridium tetani
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
Clostridium perfringens
Gas gangrene Produces toxins and enzymes causing tissue necrosis Tx- antitoxin, surgery, hyperbaric chamber
36
Clostridium difficile
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
C. diff antibiotic exposure
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
Microbial transplantation and C.diff treatment
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
Bacteriodes
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
Fusobacterium necrophorum-
cause of Lemierre syndrome, throat infection can lead to abscess
41
5 general mechanisms of antibacterial action
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
General resistance mechanisms
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
Penicillin are effective against
Many gram + cocci and some gram -
44
Cephalosporins are effective agaisnt
First gen- gram +, some gram- | Second gen- more gram -, similar gram +
45
Imipenem, meropenem effective against
Gram +, gram-, anaerobes
46
Aztreonam effective against
Gram - only
47
Vanc effective against
Gram + only
48
Aminoglycosides effective against
Aerobic gram - bacilli
49
Tetracyclines effective against
Aerobic and anaerobiv gram + and gram -, mycoplasma, chlamydia
50
Erythromycin, azithromyicn, -mycin effective against | Not clindamycin
Gram +, mycoplasma, chlamydia, legionella
51
Clindamycin effective against
Most gram +, many anaerobes
52
Sulfonamides effective against
Some gram+ and gram-
53
Quinolones effective against
Some gram + and most gram-
54
Rifampin effective against
Gram +
55
Drugs with concentration-dependent killing
aminoglycosides, fluoroquinolones, metronidazole, amphotericin Peak to MIC ration >8-10, AUC to MIC ratio >125
56
Drugs with time-dependent killing
Beta lactams, amcrolides, vanc, tetracyclines, azoles Time above MIC >60% of dosing intervas Vanc AUC-MIC >400 (achieve through trough)
57
Post antibiotic effect
Even when levels dip below MIC the organism do not immediately regrow. Impacts frequency of dosing

Therapeutics III (7 decks)

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