Intro to antibiotics

Question 1

Bactericidal

Answer 1

• drugs that are directly lethal to bacteria at clinically achievable concentrations.

Question 2

What populations are bactericidal drugs used in?

Answer 2

immunocompromised pts, (HIV, chemo, organ transplant) -> immune system suppressed/ decreased by other meds

Question 3

Bactericidal drugs

Answer 3

-Penicillin, Cephalosporins, Carbapenems, Vancomycin 
(cell wall inhibitors) 
-Aminoglycosides  
-TMP/SMX 
-Fluoroquinolones  
-Metronidazole

Question 4

Bacteriostatic drugs

Answer 4

CMT-S

• Clindamycin
• Macrolides
• Tetracycline
• Sulfanimides used alone

Question 5

Bacteriostatic

Answer 5

• drugs that slow down bacterial growth but do not cause cell death

Question 6

Bacteriostatic drugs are used in what patients

Answer 6

• Healthy patients -» immune system takes over and finishes the job by the use of phagocytes

Question 7

Prototype

Answer 7

• a drug that best represents an antibiotic category; doesn’t mean they are the most ordered or prescribed, just has the best characteristics that describe them.

Question 8

Prophylaxis

Answer 8

→ preventing infection, pre-surgery, special populations (heart valves, rheumatic fever, dental surgeries)

• If antibiotics are used post-surgery → indicates an infection is being treated
• Immunosuppressed patients (Ex: give Bactrim to an HIV patient to prevent PJP)
• Systemic antibiotic prophylaxis: IV antibiotics; given broad-spectrum antibiotics two hours before surgery.
• Used with major operations (bowel surgery, C-section, joint replacement) NOT minor surgeries

Question 9

Empiric therapy

Answer 9

-using our best guess to what organism is causing the infection
Ex: most common cause of UTIs is E. coli → use an antibiotic to treat E. coli (gram-negative rod)
Drug selection based on clinical evaluation and knowledge of which microbes are most likely to cause infection at a particular site; used as an initial treatment in patients with severe infections.

Question 10

aerobic microbes

Answer 10

grow in the presence of oxygen

Question 11

anaerobic microbes

Answer 11

-can grow in the absence of oxygen; harder to treat!
Locations: deep wounds, tissues, and internal organs
Infections: abscess formation, tissue destruction, foul-smelling pus
- Can be gram - or gram +
- C.Diff, e. Coli, clostridium botulinim, clostridium tetani

Question 12

Abx used for anaerobic microbes

Answer 12

Treatment: Flagyl (metronidazole), Clindamycin

Question 13

Narrow spectrum ABX

Answer 13

active against only a few species of microbes.
-antibiotics active against GP-cocci and GP-bacill → PCN G, Vancomycin, Erythromycin, Clindamycin

-Ex: antibiotics active against GN-aerobes → Aminoglycosides, Cephalosporins (1st & 2nd Gens)

Question 14

Broad Spectrum ABX

Answer 14

• Active against a wide variety of microbes
• Antibiotic active against both GP cocci and GN-bacilli → Cephalosporins (3rd & 5th Gens), Tetracycline, Carbapenems (imipenem), TMP/SMX, Fluoroquinolones (Ciprofloxacin)
  ○ Can markedly alter normal flora

Question 15

1st step to choosing an ABX

Answer 15

1) The identity of the infecting organism
○ Gram stain (and plating): quickest & simplest technique to identify microbes
■ performed to identify Gram-positive vs. Gram-negative, Shape (bacilli, cocci, spirilla), and metabolism requirements (aerobic versus anaerobic)
■ Gram-positive bacteria: Staph, Strep, Enterococcus
■ Gram-negative bacteria: E. coli, Shigella, Salmonella, Klebsiella, Enterobacter, Serratia marcescens, Proteus mirabilis/vulgaris, Haemophilus, Neisseria, Pseudomonas, clostridium

Question 16

What are cultures, when are they taken, how long do they take?

Answer 16

• used to identify the pathogen
  ■ Taken BEFORE anti-infectives are started!!
  ■ Can take 2-5 days (Knowlton said 48 hours)

Question 17

2nd step to choosing an ABX

Answer 17

2) Drug sensitivity of the infecting organism
○ Once bacterial growth occurs, it’s performed to identify which antibiotics are effective in killing the bacteria.
○ Uses Minimum Inhibitory Concentration (MIC): susceptibility to an antibiotic (not complete death).
○ NOT ALWAYS NEEDED; used more with pathogens with known resistance (staph)

Question 18

3rd Step to choosing an ABX

Answer 18

3) Host factors (site of infection, status of host defenses–healthy vs immunocompromised)
-● PCR testing is also used for pathogen identification
○ Ex: MRSA, HIV, CGAMD

Question 19

Selective toxicity

Answer 19

• antibiotics that are harmful to the microbe but NOT the human host.
  -○ Achieved by using antibiotics that work by manipulating the biochemical processes of the microbe and not the host.
  ■ Disruption of bacterial cell wall
  ■ Inhibition of an enzyme unique to bacteria
  ■ Disruption of protein synthesis

Question 20

Initial tx for severe infections needing immediate tx

Answer 20

Broad-spectrum

Question 21

Need to obtain specimens for identification ……..

Answer 21

• before treatment

- ■ Antibiotics can suppress microbial growth in culture and confound identification

Question 22

After C&S and identification of the pathogen what abx do you use?

Answer 22

Narrow-spectrum (more selective antibiotic)

Question 23

Factors that determine abx therapy

Answer 23

• Allergy, ability to penetrate, immunocompromised patinet, age, genetics, Foreign hardware in body

Question 24

Medication allergy

Answer 24

○ Most common causes of allergic reactions: Penicillins, cephalosporins, sulfa-drugs, and erythromycin

Question 25

intolerance

Answer 25

Nausea and vomiting

Question 26

Allergic reaction

Answer 26

itching, skin rashes, hives, SOB

Question 27

Anaphylactic rxn

Answer 27

can develop within 1 hr of taking the dose, and include difficulty breathing, shortness of breath, Respiratory stridor, and angioedema, severe hypotension, tachycardia, bronchospasm

Question 28

If patient suspects anaphylaxis symptoms..

Answer 28

discontinue medication and notify provider

Question 29

Ability to penetrate the site

Answer 29

○ Meningitis: drug needs to be able to cross BBB ■ Cephalosporins (Gen 3-5) ○ Abscess: tend to be caused by anaerobes; need to flush it out first for treatment to be effective ■ Metronidazole (Flagyl), vancomycin

Question 30

immunocompromised pt/ host

Answer 30

Use bactericidal antibiotics

Question 31

Foreign hardware within the body

Answer 31

- Need to use Bactericidal versus bacteriostatic antibiotics because phagocytes may try to “eat” the hardware. - Makes phagocytes less able to attack bacteria if they’re attacking hardware, thereby allowing microbes to flourish - Treatment often results in failure or relapse and may require removal of the hardware

Question 32

Age: infants

Answer 32

high risk for toxicity → ■ FROM EXAM 1: ■ organ system immaturity; drug responses are unusually intense and prolonged ■ Elevated drug levels= more intense response ■ Delayed elimination= prolonged response ■ Metabolism- Markedly faster until age 2, then gradual decline → Increase dose or increase intervals ■ <2 yrs. → smaller dose due to greater rate of metabolism, delayed elimination ■ >2 yrs.→ gradual ↑; larger or more frequent dose due to gradual decline of metabolism, & increasing elimination ■ Topical absorption much greater in kids → Possible Permethrin Question? ■ BBB not formed until 1 year

Question 33

Age: Children/ adolescents

Answer 33

: avoid use of certain drugs (Tetracyclines)

Question 34

Age: pregancy and lactation

Answer 34

risk to mom AND fetus (Gentamicin causes hearing loss; Sulfonamides cause kernicterus in nursing newborns)

Question 35

Age: older adults

Answer 35

heightened drug sensitivity ■ FROM EXAM 1: ■ Absorption → delayed gastric emptying ■ Distribution → Increased body fat (drug storage); Decreased muscle mass (less protein-binding sites) ■ Metabolism → Decreased activity of hepatic enzymes → decreased hepatic metabolism ■ Excretion → Decline in renal function; GFR decreases

Question 36

Genetic Factors

Answer 36

○ Sulfonamides are contraindicated for patients with G6PD deficiency (causes anemia) ○ slow, rapid, normal metabolizers

Question 37

How does antibiotic Resistance work?

Answer 37

○ Host contains lots of microbes where a few are drug resistant ○ Antibiotics kill bacteria causing the illness, as well as good bacteria protecting the body from infection. ○ The drug-resistant bacteria are now allowed to grow and take over. ○ Some bacteria give their drug-resistance to other bacteria, causing more problems

Question 38

Factors contributing to antibiotic resistance?

Answer 38

○ Spontaneous mutation ■ Change in DNA: Single drug resistance ■ Conjugation of chromosomal DNA: multi-drug resistance ■ HA-acquired infections are generally more resistant than community-acquired infections ○ Use of antibiotics in food supplies ○ Misuse (viral infections) ○ Overuse (bacteria mutate)

Question 39

Prevention methods for antibiotic resistance?

Answer 39

○ Antibiotic stewardship: giving antibiotics appropriately, and using them for the right amount of time. ○ Only take antibiotics when needed ■ NOT for viral infections (URI, otitis media) ■ Understand effect on microbe ○ Take full course of antibiotic ○ Take cultures before administering antibiotics ○ Discuss probiotics ○ Isolation precautions

Question 40

MDROs

Answer 40

○ MRSA, VRE, ESBL (Extended-spectrum Beta-lactamase producers

Question 41

Superinfections

Answer 41

● Superinfections: killing of host normal flora allows remaining microbes to grow and cause a new infection to occur. -Ex: Yeast infection, Candidiasis in the mouth, C. diff Be aware of possible superinfection with C. diff → Clindamycin* (most common), Fluroquinolones, cephalosporins, penicillins, vancomycin

Question 42

Gi Distress

Answer 42

N/V/D

Question 43

Allergic rxns

Answer 43

: rash, hives, difficulty breathing (SOB) ○ Assess BEFORE and AFTER administration ○ Dosage INDEPENDENT ○ Requires prior immune system priming → may occur during the second dose

Question 44

If allergic rxn occurs

Answer 44

■ STOP medication ■ Think about airway (ABCs); epinephrine ■ Call Rapid Response/Code Cart