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Pharmacology > Antimicrobials > Flashcards

Antimicrobials Flashcards

1
Q

What three things do anti-infectives target?

A

bacteria, viruses, and parasites (specifically target receptors/enzymes of these things that are different from mammalian/human cells, though some are shared and toxicity/organ damage can occur)

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2
Q
  1. Bacteriostatic vs 2. Bactericidal
A
  1. temporary inhibition of growth/reproduction, host defense must be intact to use these agents
  2. death of microbe, can use when host defenses are impaired
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3
Q

which antibiotics have MOAs that work outside the cells?

A
  1. cell wall inhibitors (penicillins and cephalosporins, beta-lactams)
  2. cell membrane inhibitors: amphotericin, azoles, polyenes
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4
Q

which antibiotics have MOAs that work inside the cell?

A
  1. inhibitors of protein synthesis: aminoglycosides, chloramphenicol, macrolides, lincosamides, tetracyclines, streptogramins
  2. DNA inhibitors: quinolones, metronidazoles, nitrofurantoin, sulfonamides, trimethoprims
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5
Q

sulfonamides and trimethoprims are also referred to as what

A

anti-metabolites

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6
Q

what is antibiotic prophylaxis?

A

comes in two categories

  1. prevention of infection if at risk
    - patient has TB so nurses given to prevent infection
    - recurrent disease (UTI) to prevent new infection
    - surgical prophylaxis (before/after)
  2. treatment when colonized but before disease symptoms develop
    - underlying med condition (rheumatic heart disease to prevent heart valve infection, endocarditis)
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7
Q

what is selective toxicity of antibiotics?

A

toxic to pathogen not to patient

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8
Q

use of antibiotics

A
  1. anti-infective
  2. adjunctive therapy
  3. surgical/other prophylaxis
  4. cancer chemo
  5. organ transplant
  6. prophylaxis when there’s med conditions
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9
Q

what is the gold standard for determining use of antibiotic in clinical setting?

A

laboratory culture accompanied by susceptibility data (which antibiotic will work best)

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10
Q

what does in vitro mean? what does in vivo mean

A

“in glass” mean today “in the lab”; means “in life” literally the actual results in patients (may or may not correlate with lab data)

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11
Q

what’s 1. MIC 2. MLC 3. MBC

A
  1. MIC - minimum inhibitory concentration, minimum needed to inhibit growth of the organism
  2. MLC: minimum lethal concentration, minimum concentration of drug needed to kill organism
  3. MBC: minimum bactericidal concentration, same as MLC
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12
Q

look up

A

beta-lactam testing

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13
Q
  1. narrow-spectrum vs. 2. broad-spectrum antibiotics
A
  1. only active against small group of bacteria (have to be sure you are treating those specific bacteria)
  2. work against wide variety
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14
Q
  1. empiric therapy vs. 2. focal therapy
A
  1. not sure what bacteria is, guess based on where infection is (ex lungs) and clinical factors (age, sex, other ilnesses)
    - therapy started with BROAD-SPECTRUM antibiotics
  2. switch to DOC when specific diagnosis made (hopefully monotherapy)
    - sometimes DOC determined by lab culture, sometimes from diagnosis
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15
Q

why would you choose parenteral over oral therapy

A

drug needed in high levels, needs to bass barrier like BBB

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16
Q

if an infection is in bone, heart valve, prostate, or kidney, how does this affect drug therapy with antibiotics (for example)

A

prolongs therapy

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17
Q

look up about delayed antibiotic prescribing

A

page 3

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18
Q

what is switch therapy

A

switch from parenteral to oral, severe infections first treated with parenteral then switched to oral to finish

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19
Q

what are the three phases of recovery for parenteral therapy

A
  1. infection stops progressing (stabilizes, stage 1)
  2. stage 2: improvement becomes evident
  3. stage 3: infection resolves
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20
Q

what are important signs that patient has improved on parenteral antibiotics (important for switch therapy)

A
  1. stable vital signs for > 24 hours

2. fever resolved ( 90 (>100 if HTN diagnosis) without pressor amine support

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21
Q

what are important factors to consider before discharging patient that had a serious infection and was on parenteral therapy (important for switch therapy)

A

baseline mental status, no acut comorbidity, adequate O2 on room air or POx >92% for caucasians and 94% for non-caucasians

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22
Q

do most antibiotics cross the placenta?

A

yes

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23
Q

commonly used antibiotics in pregnancy

A
  1. penicillins/cephalosporings (probably the safest group overall)
  2. macrolides: most are safe (erythromycin, clindamycin, azithromycin)
  3. anti-tubercular: INH, PAS, ethambutol for TB can be used
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24
Q

antibiotics of potential concern in pregnacy

A
  1. aminoglycosides
  2. metronidazole (FDA cate B but ok only for 2nd/3rd trimesters)
  3. nitrofurantoin (commonly used by many OBs, is FDA Cat B, but can’t use in 3rd trimester/at term)
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25
Q

antibiotics not normally used in pregnancy

A
  1. sulfa drugs
  2. quinolones
  3. tetracyclines
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26
Q

why should antibiotics be prescribed with hesitation

A

resistance ps some infections just look like bacterial infections (for viral, fungus, parasite different drugs other than antibiotics are given)

27
Q

what are beta-lactamase enzymes an example of in bacteria?

A

an example of non-genetic changes bacteria can make to form resistance, in this case it’s an enzyme (other non-genetic include going dormant, changing internal structures). remember: even topical or ocular admin of drug may cause resistance

28
Q

what is one of the most serious ADRs of antibiotics? elaborate

A

LQTS! (long QT interval syndrome); people with this syndrome have a sudden LOC/syncope/death (onset may with sudden noise or rest)
clues to existence:
- unexplained syncope esp after exertion/excitement/arousement
-fam hx of fainting
- fam hx of sudden death at young age (SCD)

other clinical risk factors for LQTS:
- electrolyte abnormalities, heart failure, hypothyroidism

Drugs that may cause LQTS
- a lot of drugs though a lot are antibiotics

29
Q

what is torsades de pointes

A

EKG findings of a fatal arrhythmia, QT prolongation and tacycardia from LQTS syndrome

30
Q

what GI effect does an antibiotic have after being in the body?

A

wipes out good flora and causes antibiotic-associated diarrhea (mild to severe)

31
Q

what’s another name for normal flora in the body? what do they do?

A

commensals in the intestines (for digestive health manufacturing vitas K and B12, and may enhance immune system

32
Q

what is CDAD?

A

Clostridium difficile associated disease, severe form of diarrhea, life-threatening; is an over-growth syndrome since on particular bacteria grows beyond normal amounts

Symptoms: watery stool with blood, abdominal cramps and high fever

hygiene precautions (wash b/c of spores); considered major HAI

33
Q

What are probiotics?

A
  • live nonpathogenic gram + bacteria and yeasts that enhance microbial growth in the intestines
  • may be used to combat the killing off of good bacteria that occurs with antibiotic therapy, may lead to flatulence and diarrhea

Examples

  • Bifididobacterium regularis (Bifidis regularis as GI suppor)
  • Saccharomyces as yeast supplements
  • Lactobacillus acidophilus and other strains
  • found in fermented dairy products, active culture yogurt, and OTC supplements like Lactinex, Florastor, Acidophilus
  • DO NOT USE IN THE IMMUNO-SUPPRESSED (may become septic)
34
Q

what are two common organ toxicities from antimicrobials?

A
  • Renal (nephrotoxic)

- CN VIII (ototoxic - hearing loss, usually with tinnitus as a warning sign)

35
Q

Renal toxicity, what can cause it (the general physiology) and what are some known offenders?

A

renal failure from….

  1. direct toxicity: ex: aminoglycosides like gentamycin
  2. allergic interstitial nephritis: can occur from any antibiotic
  3. crystallization of antibiotic in renal tubule: sulfa and anti-retroviral drugs acyclovir and indinavir
36
Q

which drugs have the MOA of inhibiting bacterial cell wall synthesis

A
  1. beta lactams! - penicilins, cephalosporins, monolactams, carbapenems (called this b/c chemical structe has a beta-lactam ring)
  2. bacitracin
  3. vancomycin
37
Q

what are bacitracin and vancomycin respectively good for?

A
  1. bacitracin - skin/eye infections (often cause by gram + Strep or Staph)
  2. vancomycin - good for antibiotic-associated diarrhea by C. diff
38
Q

How could a bacteria form resistance to a beta-lactam? How can this be avoid

A

a. can form resistance if bacteria can make a beta-lactamase enzymes (called penicillinase), enzymes chews up drug/inactivates

b. augment antibiotic with chemical adjunctive agent like clavulanate + amoxicillin (Augmentin)
OR
augment antibiotic by modifying chemical structure: methicillin (Staphcillin), cefoxitin (Mefoxin), aztreonam (Azactam), imipenem (Primaxin)

39
Q

Name
1. narrow-spectrum penicillins that are penicillinase sensitive

  1. narrow-spectrum penicillins that are penicillinase resistant
A
  1. Penicillin G, Penicilling G Benzathine (Bicillin)
    - DOC in group A beta-hemolytic strep infections (GABHS) for acute treatment and monthly prophylaxis for conditions like sickle-cell anemia; DOC for syphilis
  2. nafcillin (Unipen), methicillin (Staphcillin), dicloxacillin (Dynapen)
40
Q
  1. broad-spectrum penicillins that are penicillinase (beta-lactamase) sensitive
  2. braod-spectrum penicillins that are penicillinase (beta-lactamase) resistant
A
  1. ampicillin, amoxicillin (Amoxil)

2. augmented drugs such as clavulanate+amoxicillin (Augmentin, oral) and sulbactam + ampicillin (Unasyn IV)

41
Q

what are the extended spectrum penicillins

A

ticaracillin (Ticar), ticarcillin+clavulanate (Timentin), piperacillin (Pipracil), etc

42
Q

how are cephalosporins often referred to?

A

as generations (based on characteristics of the cephalosporin such as narrow? broad? crosses BBB?

43
Q

common AEs of cephalosporings

A

bleeding dyscrasia (can cause bleeding) like with cegamandole (Mandol) and cefoperazone (Cefobid)

hemolysis: cefotetan (Cefotan), ceftriaxone (Rocephin)

44
Q

what are the first generation cephalosporins?

A

a. oral cephalexin (Keflex)
b. cephadroxil (Duricef)

  • do not cross BB, not useful for resistant skin infections
  • useful for UTI and skin infections, second line for Strep infections
45
Q

what are the second generation cephalosporings?

A

a. oral cefaclor (Ceclor)
b. cefprozil (Cefzil)
c. cepodoxime (Vantin)
d. loracarbef (Lorabid)
- first four sort of go together b/c oral-
e. oral/parenteral cefuroxime (Ceftin)
f parenteral cefamandole (Mandol), cefonicid (Monocid), cefoxitin (Mefoxin)

46
Q

third generation cephalosporins

A
  • can cros BBB-
    1. oral cefixime (Suprax), ceftibuten (Cedax)
    3. parenteral ceftriaxone (Rocephin), cefotaxime (Claforan), ceftazidime (Fortaz), cefdinir (Omnicef), cefditoren (Spectracef)

note: ceftriaxone cannot be administered with Ca-containing products in the IV (death reported in neonates), caution with neonates and jaundiced infants

47
Q

what are the fourth genereation cephalosporins?

A

cefpirome (Cefrom)

48
Q

What are some other cell-wall inhibitors aside from the beta-lactams, bacitracin, and vancomycin?

A
  1. for serious HAIs
    - monobactam: parenteral aztreozam (Azactam)
    - carbapenems: imipenem (Primaxin), meropenem (Merem), ertapenem (Invanz), doripemem (Doribax)
  2. one-dose antibiotic for UTIs
    - phosphoenolpyuvate transferase inhibitors: fofomycin (Monurol) -> comes in a sachet or bag of granules that dissolves in water
  3. for complicated wound/skin infections: cyclic lipopeptides: daptomycin (Cubicin IV) -> has added MOA of also inhibiting bacterial protein synthesis called dual-action MOA
49
Q

What are the allergic reactions to penicillins, cephalosporings, and carbapenems

A
  1. Immediate Type I Hypersensitivity serious allergic reaction (anaphylactoid)
    SYMPTOMS: life-threatening, bronchospasm, angioedema, urticaria based on IgE release
  • mean cannot have ANY penicillin, cephalosporin, carbapenem, but if must have then desensitization must be done prior to dosing
    NOTE: 20% of those with reaction to penicillin, also have reaction to cephalosporins/carbapenems
  1. Delayed, non-urticarial rash type of reaciont
    - if not itchy/urticarial, prob not IgE mediated and not serious
    - most can take cephalos w/out problem
    - cephalos lessl ikely to cause: cefdinir (Omnicef), cefuroxime (Ceftin), cefpodoxime (Vantin), ceftriaxone (Rocephin) b/c of side chains
  2. Idiopathic type of reaction
    - patients with viral infection (eg EBV/mononucleosis) often get a non-allergic rash when taking ampicillin or amoxicillin, NOT true of penicillin allergy
  3. Other side effects
    - may report “allergy” symptoms like nausea/diarrhea, could be idiosyncratic (personal) med reaction, but no necessarily contraindication
50
Q

remember when charting allergic reactions

A

want to chart what type, what symptoms etc

51
Q

Drugs with the MOA of inhibition of bacterial protein synthesis

A
  • aminoglycosides, tetracyclines, macrolides (erythromycins), chloramphenicol, lincosamides (lincomycin), oxazolidinones
  • these may be either bacteriostatic or bactericidal
  • MOA: bind to ribosomes in cell and prevent synthesis of bacterial proteins; may have toxicity b/c our own cell mitochondria have similar ribosomes as bacteria
52
Q

The aminoglycosides

A

(bactericidal)
1. useful in serious infections like sepsis

  • parenteral: gentamycin (Garamycin), tobramycin, amikacin, streptomycin
  • some are opthalmic ointments
  • oral drugs are toxic and aminoglycs given orally remain in intestines and not absorbed into system (used prior to bowel surgery to sterilize bowl) -> include kanamycin and neomycin

AEs: nephrotoxicity - dose adjustment;
ototoxicity - ask if have tinnitus
-> to minimize toxicity, labs for peak and trough blood levels

53
Q

The macrolides

A

(bactericidal)

  1. Erythromycins: erythromycin (EES, ERY-C, liosone susp), clarithromycin (Biaxin bid and Biaxin XL once daily), azithromycin (Zithromax and Zmax, an opthalmic Azaside)
  2. Ketolides: telithromycin (Ketek)
    - this has hepatic toxicity risk (black box, no for use in myasthenia gravis or prior liver disease)
    - can cause LQTS
  3. Lincomycins: clindamycin (Cleocin), lincomycin (Lincocin)
    - vag preps include Cleocin Vaginal Cream for BV (Gardnerella vaginalis)
    - topical preps are useful for acne vulgaris (Cleocin T topical)
    - if taken orally or IV, may cause C diff overgrowth (severe antibiotic-associated diarrhea)
54
Q

Info on erythromycins

A

USES

  1. . think above the diaphragm (resp, ear-nose throat, conjunctivitis)
  2. STD/gyno infections
  3. bacteria associated with gastric ulcer (Helicobacter pylor) and STD/GYN gastric ulcer
  4. topically for acne vulgaris
  5. prevent opthalmia neonatorum due to chlamydia/GC

AEs: GI (N/D), since is a prokinetic agents (promotes GI muscular activity)

Drug-drug: erythromycin and clarithromycin have probably the worst drug-drug potential

SPECIAL

  1. estolate for children (eg ilosone) available as liquid but high incidence of cholestatic hepatitis in adults (don’t use in adults
  2. succinate can be given to all ages but usually only in tablets
  3. Zithromax: given 3-5 days b/c has effect for next 10 days
  4. Zmax: version of azithromycin is XR suspension of azithromycin microspheres
55
Q

What are the bacteriostatic drugs with the MOA of inhibition of bacterial protein synthesis

A
  1. chloramphenicol (PO/IV): toxicity limits its use can cause Gray Baby Syndrome, aplastic anemia
    (usually reserved for meningitis, typhoid fever, epiglottitis that are all severe and life-threatening)
  2. tetracyclines: very commonly used drug
    - for acne vulgaris, STD, Lyme disease, anthrax
    AEs -> not under 8 yo due to bones/teeth effects; not in pregnant or nursing women
    DRUGS: tetracycline, doxycycline (Vibramycin), minocycline (Minocin, Solodyn)
    - most need to be taken on an empty stomach for proper absorption
  3. streptograminins: Synercid = IV combo of quinupristin and dalfopristin
    - used in settings like graft infections, prothetic valve infections, peritonitis, catheter-associated infections (reserved for severe infections)
    AEs: myalgias, thrombophlebitis, hepatic dysfunction
  4. oxazolidinones: oral/IV drug linezolid (Zyvox)
    - reserved for well-documented VRE (vancomycin resistant enterococcus)
  5. glycylcyclines: tygecycline (Tygacil) IV
    - reserved for complicated abdominal infections, skin infections and resistant infetions like MRSA and VRE
    AEs: pregnancy cat D (teratogenic); don’t use in nursing women or child below age 8
  6. Topical drugs
    a. mupirocin (Bactroban ointment)
    b. retapamulin (Altabax ointment)
    - useful for impetigo
    - useful for nasal carriage of Staph using Bactroban nasal ointment 2% as single-use tubes for healthcare workers in hospital setting to reduce nosocomial Staph infections (for patients preop too carrying nasal Staph)
56
Q

anti-microbials with MOA of inhibition of bacterial dna synthesis or action

A
  • sometimes called anti-metabolites
  1. sulfonamides/other sulfa drugs
  2. trimethoprim
  3. quinolones, metronidazole, nitrofurantoin
  4. rifampin (for TB)
  5. pyrimethamine (for parasites)
  6. actinomycins and mitomycins - so toxic use for cancer chemo not as antibiotics
57
Q

Info on nitrofurantoin (Macrodantin)

A
  • urinary pathogens but limited in spectrum
  • urinary pH should be 6.0 or less (acid) to insure the drug will work

AEs: don’t give if renal insufficient, DON’T give to term (third trimester) pregnant woman or newborn (may induce hemolysis in baby), long-term use = pulmonary toxicity

58
Q

AEs with quinolones and fluoroquinolones (FQ)

A
  1. Peds: usually not for kids under 16-18 due to bone, teeth, kidney possible damage
    - however, ciprofloxacin (Cipro) approed for complicated UTI and kidney infections from 1 yo and up, also for post-exposure treatment of inhalational anthrax in children
  2. Pregnancy/nursing - NO
  3. Geriatrics: may complain of nightmares/disturbed sleep
    - tendon rupture is risk for any of these drugs (in elderly osteoporosis is always a concern)
  4. Cardiac AEs: QT prolongation, not used in heart block patients b/c of LQTS
  5. metabolic: may cause severe hypoglycemia in those on diabetes drugs or hx of diabetes
  6. Other: phototoxicity
    - also peripheral neuropathy (look for symptoms of burning, tingling, numbness)
59
Q

Quinolones info

A
  1. really the first generation of these drugs
  2. older drugs for UTIS: nalidixic acid (Negram); clinoxacin (Cinobac)

NOTE: when people say quinolones they really mean the newer category of fluoroquinolones

60
Q

Fluoroquinolones (FQ)

A
  • second-generation of quinolones

USES

a. most for UTIs
b. some for skin/resp infections (sinusitis, pneumonia)
c. anthrax treament

DRUGS

  1. . ciprofloxacin (Cipro, Cipro XR, Proquin XR) for resp, sinusitis, skin, joint, GYN infections
  2. . norfloxacin (Noroxin) for UTI only
  3. ofloxacin (Floxin) for UTI/GC
  4. lomefloxacin (Maxaquin) for UTI and some pneumonias
  5. levofloxacin (Levaquin) for UTI pneumonia, sinusitis, skin
  6. moxifloxacin (Avelox, Avelox IV) for pneumonia, sinusitis, chronic bronchitis, skin/wound infections, abdominal infections
  7. gemifloxacin (Factive) - pneumonia, bronchitis
  8. trovafloxacin (Trovan) - restricted to severe infections b/c of toxicity can cause fatal panreatitis and hepatitis

— someitmes you’ll here that the resp FQs are moxifloxacin, levofloxacin, and gemifloxacin

61
Q

Sulfonamides

A
  • also called anti-metabolite or anti-folate

AEs: can cause fever, rash, photosensitivity, nausea/vomitting, Stevens-Johnson syndrome (serum sickness), urinary crystalization (force fluids when using), kernicterus in neonate
**NOT used in pregnancy
USES: UTIs, MRSA

  • often combined with trimethoprim antibiotic (TMP/SMX)

DRUGS

  1. sulfadizine and sulfapyridine
  2. sulfisoxazole (Gantrisin): UTI/pyelonephritis
  3. sulfamethoxazole mixed with trimethoprim (as cotrimoxazole = Septra, Bactrim, TMP-SMZ): PO/IV for UTI, traveler’s diarrhea, sepsis, MRSA
  4. topical sulfa drug Silver sulfadizine (Silvadene) for burn patients
  5. surgical bowel preps sulfasalazine (Azulfadine) taken orally not absorbed systemically – for inflammatory bowel diesase (Crohn’s, ulcerative colitis)
62
Q

Trimethoprim info

A
  • anti-folate drug
  • Trimpex is drug alone
  • combined with sulfamethoxazole = catrimoxazole, TMP-SMX, Septra, Bactrim
63
Q

metronidazole and other imidazoles info

A

DRUGS

a. metronidazole (Flagyl, MetroGel, others)
b. tinidazole (Tindamax)

USES

  • anti-protozoal for Trichomonas vaginal infections
  • GYN bacterial infections
  • GI bacterial and protozoal infections (such as Giardia)
  • alternative therapy of antibiotic associated enterocolitis
  • surgical bowel rep
  • topically for acne rosacea

AEs
- if taken with alcohol get a disulfiram-liek reaction (flushign, vommiting, headache)

OTHER
- take with FOOD, don’t take with alcohol

Pharmacology (7 decks)

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