Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Int Medicine > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

Name 4 antibiotics that cover MRSA

A

MRSA is covered by

  1. vancomycin
  2. linezolid
  3. daptomycin
  4. ceftaroline

Exceptions:

  • Daptomycin is inactivated by lung surfactant – don’t use in pneumonia
  • Linezolid is bacteriostatic (mainly)– don’t use in bloodstream infections (although it can be used for VRE bacteremia)
  • Ceftaroline is vancomycin and ceftriaxone rolled into one loveable fuzzball

Ref: https://www.pharmacyjoe.com/tips-for-memorizing-antibiotic-spectrum-of-activity/

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Piperacillin-tazobactam and the carbapenems ertapenem, meropenem, doripenem, and imipenem provides which coverage?

A

Piperacillin-tazobactam and the carbapenems ertapenem, meropenem, doripenem, and imipenem cover gram positives, gram negatives, and anaerobes

Exceptions:

  • Ertapenem doesn’t cover pseudomonas
  • Piperacillin-tazobactam doesn’t cover ESBL well enough to be used in severe infections (although it probably works for UTI)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Quinolones ciprofloxacin, levofloxacin, and moxifloxacin cover gram positives and gram negatives (double check your local resistance patterns!!!).

A

Quinolones ciprofloxacin, levofloxacin, and moxifloxacin cover gram positives and gram negatives (double check your local resistance patterns!!!).

Exceptions:

  • Ciprofloxacin is weak against strep pneumoniae, but causes the least QTC prolongation and probably doesn’t cause torsades
  • Moxifloxacin is best against anaerobes but has no pseudomonas coverage
  • Moxifloxacin is hepatically metabolized – this is a double-edged sword as it has no dose adjustment in renal failure but can’t be used for a UTI
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Cephalosporins for empiric use in the ICU are cefepime, ceftriaxone, ceftazidime, and ceftaroline. They cover what organisms?

A

Cephalosporins for empiric use in the ICU are cefepime, ceftriaxone, ceftazidime, and ceftaroline. They cover gram positives and gram negatives.

Exceptions:

  • Only cefepime and ceftazidime for pseudomonas
  • None cover enterococcus (remember – this shows up on the gram stain as “gram-positive cocci resembling strep!”)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Which class of antibiotics are derived from cultures of streptomyces? Name 3 drugs in this ckass

A

Class: Aminoglycosides. Drugs: Gentamicin, Tobramycin, and amikacin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

1)Name gram-positive aerobic cocci -in clusters -in pair/chains 2)Name gram-positive anaerobic cocci

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

1) Name species of Gram-negative aerobic cocci
2) Name species Gram-negative anaerobic cocci

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the MoA of β-lactam antibiotics? Cephalosporins? Differences between the two?

A

Cephalosporins are bactericidal and have the same mode of action as other β-lactam antibiotics (such as penicillins), but are less susceptible to β-lactamases. Cephalosporins disrupt the synthesis of the peptidoglycan layer forming the bacterial cell wall. -The peptidoglycan layer is important for cell wall structural integrity. The final transpeptidation step in the synthesis of the peptidoglycan is facilitated by penicillin-binding proteins (PBPs). -PBPs bind to the D-Ala-D-Ala at the end of muropeptides (peptidoglycan precursors) to crosslink the peptidoglycan. -Beta-lactam antibiotics mimic the D-Ala-D-Ala site, thereby irreversibly inhibiting PBP crosslinking of peptidoglycan.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

1)Name species of gram-positive aerobic rods 2)Name species of gram-positive anaerobic rods

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

1)Name species of gram-negative aerobic rods -lactose fermenting -non-lactose fermenting 2)Name species of gram-negative anaerobic rods

A

*Serratia and Citrobacter spp can appear initially as non-lactose fermenting due to slow fermentation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Interpretations of Key Phrases

  • “Gram positive cocci in clusters” may suggest ____________
  • “Gram positive cocci in pairs and chains” may suggest _____
  • “Gram negative coccobacilli” may suggest ______
  • “Lactose-positive gram negative rods” may suggest _____
  • “Lactose-negative gram negative rods” may suggest _____
  • “Branching Gram positive rods, modified acid fast stain positive” may suggest _____
  • “Acid fast bacilli” may suggest _____
  • “Yeast” suggests ______spp. “Round Yeast” suggests _____ “Fungal elements or hyphal elements” suggest ______
A

. 7) . 8). 9)

  • “Gram positive cocci in clusters” may suggest Staphyloccocus species​
  • “Gram positive cocci in pairs and chains” may suggest Streptococcus species or Enterococcus species
  • “Gram negative coccobacilli” may suggest Haemophilus species
  • “Lactose-positive gram negative rods” may suggest Enterobacteriaceae, such as E. coli, Klebsiella, or Enterobacter spp.
  • “Lactose-negative gram negative rods” may suggest Pseudomonas
  • “Branching Gram positive rods, modified acid fast stain positive” may suggest Nocardia or Streptomyces species
  • “Acid fast bacilli” may suggest Mycobacterium species
  • “Yeast” suggests Candida spp. “Round Yeast” suggests Cryptococcus spp. “Fungal elements or hyphal elements” suggest filamentous fungi (moulds).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q
  • What are pathogens in blood cultures?
  • What are likely contaminants/normal flora in blood cultures
  • What’s the significance of multiple positive blood cultures from a single venipuncture or a line?
A
  • Pathogen: Any organism isolated
  • Likely contaminants/normal flora
    • Coagulase-negative staphylococci
    • Alpha-hemolytic (viridans) streptococci
    • Bacillus spp.
    • Corynebacterium spp. (Except C. jeikeium)
    • Propionibacteirum acnes
    • Micrococcus
  • Multiple positive bottle drawn from a single venipuncture (or sequentially through one line) are not considered separately when evaluating the potential significance of a likely contaminant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q
  • What are pathogens in urine cultures?
  • Which organisms are involved in contamination?
A
  • Pathogens
    • Enterobacteriaceae
    • Enterococcus spp
    • Pseudomonas spp
    • Group B streptococci (in pregnancy)
    • S. aureus
    • S. saprophyticus
    • Yeast
  • Significance determined by colony count e.g. contamination usually in small numbers
    • Corynebacterium
    • Coagulase-negative staphylcocci
    • Alpha-hemolytic streptococci
    • Lactobacillus spp
    • Gram-negative rods
    • Bacillus spp

urine from stomas and conduits are not sterile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q
  • What are pathogens in tissue/body fluid cultures?
  • What are likely contaminants/normal flora in tissue/body fluid cultures?
A
  • Pathogens Any organism isolated; use judgment to evaluate the possibility of normal flora being present in relation to the source of the specimen.
  • Contaminants/normal flora in tissue/body fluids
    • Eye/Ear
      • Coagulase-negative staphylococci
      • Non-hemolytic streptococci
      • Alpha-hemolytic streptococci
      • Corynebacterium
    • Skin
      • Coagulase-negative staphylococci
      • P. acnes
      • Corynebacterium
      • Alpha-hemolytic streptococci
      • Bacillus spp.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q
  • What are pathogens in the GI tract?
  • What are likely contaminants/normal flora in the GI tract?
A
  • Pathogens
    • Salmonella spp
    • Shigella spp
    • Campylobacter jejuni
    • Aeromonas/Plesiomonas
    • Yersinia enterocolitica
    • Vibrio spp
  • Likely contaminants/normal flora
    • Enterobacteriaceae
    • Staphylococcus spp
    • Streptococcus spp
    • Enterococcus spp
    • Pseudomonas spp
    • Anaerobes
    • Yeast
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q
  • What are pathogens in the respiratory tract?
  • What are likely contaminants/normal flora in the respiratory tract?
A
  • Pathogens
  • Group A streptococci
  • Streptococcus pneumoniae*
  • S. aureus (many)
  • H. influenzae*
  • Neisseria meningitidis
  • Enterobacteriaceae (many)
  • Pseudomonas (many)
  • Nocardia spp
  • Moraxella catarrhalis* (many)

*S. pneumoniae, H. influenze, and M. catarrhalis are all members of the normal respiratory flora and the presence of these organisms in a respiratory culture alone does not necessarily indicate infection.

  • Likely contaminants/normal flora
    • Staphylcoccus spp
    • Alpha-hemolytic streptococci
    • Gram-negative rods
    • Beta-hemolytic streptococci other than Group A
    • Saprophytic Neisseria spp
    • Enterococcus spp
    • Corynebacterium spp
    • Bacillus spp
    • Yeast
    • Anaerobes
    • Haemophilus spp
    • Micrococcus spp
    • Stomatococcus spp (Rothia)
17
Q
  • Which bacteria do stool cultures typically test for?
  • If you want to look for other bacteria, what cultures should you look for?
  • A total of ___ samples of consecutive days will increase probability of isolating etiologic agent in > 95% of cases
  • When is it inappropriate to order a stool culture for a hospitalized patient?
A
  • Salmonella, Shigella spp, Campylobacter spp.
  • If Yersinia enterocolitica or Vibrio sp are suspected, alert the laboratory as specialized media are required to optimize recovery of these organisms.
  • 3
  • It is inappropriate to order a stool culture on patients who develop diarrhea after >3 days in the hospital given most likely will be C.difficile
18
Q
  • How is C.diff testing performed?
  • If C.diff testing is negative, does testing need to be done? Should you do empiric therapy?
  • Should test of cure be done?
A
  • The C. difficile testing is performed by nucleic acid amplification test (NAAT).
  • This test is >99% sensitive and specific, therefore empiric therapy for patients with negative C. difficile NAAT should be avoided. Due to the high sensitivity and specificity, repeat testing is unnecessary.
  • This test is not indicated for test of cure, as patients may remain positive for 30 days following clinical cure. Many patients will continue to carry the organism without any clinical manifestations of colitis and need no further treatment.
19
Q
  • Minimum amount blood to be drawn?
  • Should you delay antibiotics to obtain cultures?
  • What happens if the patient is persistently febrile without a source of infection?
A
  • A minimum of two sets (one set = one anaerobic and one aerobic bottle) should always be obtained. The minimum volume of blood needed per bottle for adults is 10 ml. Thus, the minimum volume of blood per set is 20 ml.
  • Ideally, blood cultures should be drawn before the first dose of antibiotics, but antibiotics should not be withheld because of a delay in getting blood drawn.
  • If a patient is persistently febrile without a defined source of infection, obtain two sets of cultures per day for 48-72 hours. Do not continue drawing daily blood cultures beyond 72 hours.
  • If a vascular catheter is thought to be a potential site of infection, blood should be drawn from the catheter and the periphery.
20
Q

Lower respiratory tract

  • Appropriate specimens to identify pathogens causing disease of the lower respiratory tract (tracheitis, bronchitis, pneumonia, lung abscess, and empyema) include samples from?

Upper respiratory tract:

  • Appropriate specimens to identify pathogens causing respiratory tract infections include samples from?
A

Lower respiratory tract

  • expectorated and induced sputum, endotracheal tube aspirations, bronchial brushings, washes, or alveolar lavages collected during bronchoscopy and pleural fluid.
  • Lower respiratory tract specimens (particularly sputum) are assessed for quality (lack of contaminating oral respiratory tract flora and epithelial cells) through a Gram stain. If the specimen shows a lack of PMNs but many epithelial cells and oropharyngeal flora, the specimen will be rejected by the laboratory and another specimen must be collected for culture.

Upper respiratory tract

  • samples from the nasopharynx, throat, oral ulcerations
  • Nares swabs and nasopharyngeal swabs and washes are not acceptable for routine bacterial culture. If Bordatella pertussis or B. parapertussis is suspected, a nasopharyngeal specimen should be submitted for B. pertussis/parapertussis PCR
21
Q

See UCLA website: https://res.mednet.ucla.edu/AntibioticsGuide

A
22
Q

Differences between Pharmacodynamics and Pharmacokinetics?

A

Pharmacokinetics versus pharmacodynamics

  • Pharmacokinetics mathematically describe the relationship of antibiotic concentration to time. Terminology that is typically associated with pharmacokinetics includes: absorption, distribution, metabolism, elimination, half-life, volume of distribution, and area under the concentration-time curve (AUC).
  • Pharmacodynamics describe the relationship of antibiotic concentration to pharmacologic effect or microorganism death. The three main pharmacodynamic parameters that are used are the peak to minimal inhibitory concentration ratio (peak/MIC), the AUC to MIC ratio (AUC/MIC), and the time the drug concentration remains above the MIC (T>MIC).
23
Q

Give examples of gram-negative enterobacteriacae

Give examples of gram-negative non-lactose fermenters

A
24
Q

Give examples of anti-pseudomonal beta-lactams

Give the drawbacks of each.

A
  • cefepime
  • piperacillin-tazobactam
  • ceftazidine
  • meropenem
25
Q

Summary slide for treatment of common gram-positive bacteria

A
  • General antimicrobial activity guidance only.
  • Always take into account patient history (previous antibiotic & pathogen history) and local antibiogramdata
26
Q

Summary slide for gram-negative bacteria trmt

A
  • General antimicrobial activity guidance only.
  • Always take into account patient history (previous antibiotic & pathogen history) and local antibiogramdata
27
Q

What are SPACE organisms?

A
  • Colloquial acronym for gram-negative bacteria that have inducible, chromosomal beta-lactamase genes known as AmpC (CTX-M for enterobacter).
  • Resistance may not be detectable initially, but appears after a period of exposure to beta-lactam antibiotics
  • Acinobacter more common in nursing homes
  • Other organisms in the class: Cronobacter, Edwardsiella, Hafnia, Morganella
28
Q

ESBL

  • Definition
  • Pathogens responsible
  • Risk factors
  • Treatment
A
29
Q

What are some concerns regarding cefepime?

A
  • Needs to be appropriately dosed renally
  • Excess amounts –> neurologic issues, interstitial nephritis/necrosis
  • If you want anaerobic coverage, you need to add metronidazole
30
Q

What are concerns about Pip-Tazo?

A
  • There’s toxicty esp when combining with vanco
  • Ned to see whether you need additional vanco coverage e.g. lines, MRSA
  • High sodium load( need to keep in mind with hyperNa or fluid overload)
  • Positive is that you don’t need add another ABX for anaerobic coverage
31
Q

Discuss use of Ceftazidine

A
  • Not used much but it is the last ABX that pseudomonas is resistant to.
  • PRovides minimal gram+ coverage e.g. strep / staph
  • If you use this, consider extra gram+ coverage
    • e.g. lines or oral mucositis
    • add daptomicin, linezolid, or vanc
  • Cross reactivity to PCN is less compared to cefepime, Pip-Tazo, ceftriaxone
32
Q

Use of carbopenems?

A
  • Meropenem is usually the main agent to use if there’s no improvement with cefepime/vacno . If patient has MDR, mayt consider using this first
  • Irtapenem doesn’t cover all pseudomonas
  • Try not to use carbopenems at baseline b/c of resistance it may induce.
    • If worried about pseudomonas,
33
Q

What are some ABX to treat MRSA?

A
  • Tetracyclines
  • Bactrim
  • Linezolid
    • use this esp in MRSA PNAs?
  • Daptomycin
    • do NOT use in MRSA infections in alveoli/lung b/c will be inactivated.
    • Can use for bacteremias however.
    • Use for serious E.faecium infections
34
Q

What ABX would you use for VRE?

A

Daptomycin or Linezolid

35
Q

What’s the controversy with enterococcus faecalis?

A
36
Q

What are examples of coagulase negative staph? coagulase positive staph?

A
37
Q
A

Int Medicine (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions