Antibiotics

Question 1

How do you to empiric therapy

Answer 1

We dont the mechanism

• give broad spectrum Abx at 1st for serious infection
• then culture and find what the actual bacteria is
• start with big guns and then move to the small guns when you figure it out

Question 2

How do you use abx

Answer 2

• obtain data
• collect culture
• tailor dose and route of administration
• move from broad-based empires therapy to more specific, narrow spectrum therapy once an etiological diagnosis is available

Question 3

Most serious consequence of misuse of antibiotics

Answer 3

Widespread emergence of antibiotic resistance

Question 4

Immunocompetent individuals and abx

Answer 4

Infectious agent is external

Question 5

Immunocompromised individuals and infectious agent

Answer 5

Internal

Question 6

Minimum inhibitory concentration (MIC)

Answer 6

The lowest concentration of abx that inhibits bacterial growth after 24 hours in a specific growth medium, if you remove antibiotic the organism will grow

Question 7

Minimum bacterialcidal concentration (MBC)

Answer 7

The lowest concentration of antibiotic that prevents growth on antibiotic-free subculture, i.e. it kills 99.9% of the bacteria; culture bacteria with antibiotic then replace with antibiotic-free medium; if no growth, then the bacteria are dead

Question 8

Testing panel

Answer 8

Want to start with narrow spectrum drug

• oxacilin to target staph
• if it doesn’t kill, move to group2 or 3

Question 9

Difference between imperil therapy and testing panel for abx

Answer 9

Imperic

• broad to narrow for Tx
• starts with emipenem

Testing

• cultures and want to kill that particular bacteria.
• narrow to broad
• start with oxicillin

Question 10

Micorbiostatic agents

Answer 10

Inhibit growth of organisms but do not kill them; the hosts immune system must be effective to eradicate the bug

Question 11

Microbiocidal agents

Answer 11

Particularly effective immunocompromised individual

-most Abx are this

Question 12

Absorption of abx

Answer 12

Oral is preferred

Parenteral is necessary if infection is life threatening

Question 13

Tissue distribution of abx

Answer 13

Meningitis

-some infections take months to treat

Question 14

Antibiotic elimination

Answer 14

• almost all antimicrobials are excreted to some extent by kidney
• doses must be adjusted in renal failure; only a few antibiotics are excreted by biliary (liver) routes and they don’t require dosage adjustment in renal failure

Question 15

Synergy of Ab

Answer 15

In cases where 1+1>2

Question 16

What drugs do we used in synergy

Answer 16

Ags+Pens

TMP+SMx (folate metab inhibition)

Question 17

Extended antimicrobial spectrum

Answer 17

Empiric

Question 18

When do we use combination therapy in abx

Answer 18

Prevention of resistance in people who are immunocompromised (TB and HIV)

Question 19

Treatment of mixed infections

Answer 19

Aerobic + anaerobic

Question 20

Failure to modify dosage when elimation pathways are impaired

Answer 20

Toxicity increases as renal functions decreases. Have to adjust for renal. Creatinine clearance. Must lower dose

Question 21

Signs of infection

Answer 21

• fever >98.6
• WBC counts betwee 4000-10000
• increased bands
• pain and inflammation