Antibiotic Slide Deck Flashcards
What are common causes of drug resistance?
- Overuse of broad-spectrum abx.
- Over prescription of abx. for viral illnesses
- Use of abx in animals that enter the food chain
Which type of bacteria has a cytoplasmic membrane surrounded by a touch rigid mesh cell wall?
Gram +
Ex: staph aureus, strep pneumoniae, clostridium - stain purple
Which type of bacteria has a thin cell wall surrounded by a second lipid membrane?
Gram -
Ex: E. coli, pseudomonas, H. pylori, Neisseria, gonerrhea, salmonella - stain pink
What type of antibiotic stops the bacteria from growing but does not kill it?
Bacteriostatic
What type of antibiotic kills the bacteria?
Bactericidal - important to use this type in patients that are immunocompromised
Important factors to keep in mind when prescribing antibiotics:
- immune system function
- renal and hepatic function
- Age
- Pregnancy/lactation
- Risk for multi-drug-resistance organisms
- Patient adherence: lowest frequency for the shortest duration
- cost effective - for kids: taste good and most concentrated dose
What is the MOA of the penicillins?
Inhibit the biosynthesis of peptidoglycan bacterial cell wall
Penicillin V and Penicillin G Benzathine are active against what type of organisms?
Are they narrow or broad-spectrum?
Narrow spectrum
Most effective against gram +
Mostly:
- S. pneumoniae, Group A strep (GABHS) –> bactericidal Pen V (oral) is best for group A beta-hemolytic strep - strep throat/pharyngitis
- syphilis infection (T. pallidum) –> Pen G (IV) best for
Amoxicillin and Augmentin (Amox/Clavulanic Acid) are active against what type of organisms?
Broad spectrum, bactericidal
Gram +/-
- Amoxicillin* - 1st line for AOM and sinusitis
- Augmentin* (Amox/Clavulanic acid) - 1st line fx for bites, UTI in pregnancy
PCNs Adverse Drug Reactions (ADR)
- serious allergic hx (anaphylaxis)
- Rash - Stevens-Johnson syndrome
- GI (N/V/D)
- possible C.Diff associated diarrhea (CDAD)
- Fungal overgrowth/candidiasis - Vaginitis
Cephalosporin MOA
- Inhibit mucopeptide synthesis in the bacterial cell wall Bactericidal
- 5 generation that is increasing in gram (-) coverage and less gm (+) coverage
Common Gm (+) and where the common infections they cause
•Staphylococcus aureus
- Commonly causes skin infections
- Can also cause endocarditis, sepsis, osteomyelitis, pneumonia
- -Methicillin-resistant (MRSA) and methicillin-sensitive (MSSA)*
•Streptococcus Groups A,B,C,F,G
–Pyogenes (pharyngitis [GAS], impetigo, cellulitis)
–Pneumoniae (pneumonia, meningitis, sepsis)
–Agalactiae (meningitis, vaginitis [GBS], UTI, endocarditis, skin infection)
– Significant Macrolide resistance
•Enterococcus faecalis
–Anaerobic
–Can cause UTI, prostatitis, intra-abdominal infections, cellulitis, endocarditis
•Bacilli
–Lactobacilli -present in the mouth, vagina
–C. difficile
•Listeria
Common Gm (-) organisms and the infections they cause
•Escherichia coli
–Found in the intestines of humans and animals
–Responsible for:
- f_ood-borne illness (traveler’s diarrhea)_
- UTI
- cholecystitis, sepsis
•Pseudomonas aeruginosa
–Most common in hospitalized patients
–Can cause otitis externa, pneumonia, wound infection, UTI, sepsis
•Klebsiella pneumoniae
–Colonizes the human mouth and gut
–Commonly causes Pneumonia, UTI, sepsis
– Risks: ETOH use, DM
•Neisseria gonorrhoeae
•Haemophilus influenzae
–Pneumonia, bronchitis, otitis media, c_ellulitis, infectious arthritis_
How does the spectrum of activity differ between generations of Cephalosporins?
-Earlier generations have good gram + coverage and less gram - coverage
-Later generations have better gram - coverage and less gram + coverage
Cephalosporins ADRs
- C. diff-associated infx in adults (Clostridioles)
- Hypersensitivity rx (most common) - cross rx PCN allergy (anaphylaxis, rash)
- Hemolytic anemia,
- Neutropenia, Leukopenia,
- Coagulation abnormalities (thrombocytopenia)
Cephalosporins cautions/CIs
- hx of PCN allergy with anaphylaxis or hypersensitivity rx
- -safe in pregnancy/lactation and pediatrics
- The stronger the drug (later generation)-the more chance of a C. Diff infection
What drug is in the glycopeptide class?
Vancomycin (PO)
Vancomycin MOA and indication
MOA: inhibits cell wall synthesis by binding to the D-A1a-D-A1a protein in the cell wall; narrow, only Gm+
- oral is not well absorbed so usually IV admin
- stays in the GI tract
- used for C. diff. infection (given only orally for C.diff)
- Corynebacterium, Listeria, Lactobicillus, Actinomyces, Clostridium
Vancomycin (oral) ADRs
- ototoxicity
- nephrotoxicity
** monitoring for hearing and renal function
Lincosamides Class (Clindamycin) active against/MOA
Clindamycin
narrow, Gm + , bacteriostatic
MOA: inhibits protein synthesis by binding to the 50S subunit of bacterial ribosome
Indications: MRSA skin infections, dental infections, acne (topical)
-Carries highest risk for C. Diff
Clindamycin: education
- take w/ full glass of water
- sit or stand for 30 minutes after dose
- call the clinic if diarrhea occurs
Macrolides: MOA/indications
Azithromycin, Erythromycin, Clarithromycin
- Gm + / - and atypical
- Bacteriostatic @ low dose
- Bacteriocidal @ high dose
- Consider safe in pregnancy
- Alternative to penicillin allergy
- Consider macrolide-resistant S.pneumoniae if pt has taken a macrolide in the past 3 months
- Convenient dosing (azithromycin[Z-pack]) only 5 days
MOA: inhibits RNA-dependent protein synthesis by binding to the 50S subunit
*Indications: *Think respiratory for this class**
- 1st line CAP
- 1st line pertussis
- 1st line chlamydia (tx urethritis 2nd to chlamydia)
*
Macrolides: ADRs
- potent CYP450 inhibitor (esp erythromycin and Clarithromycin [Biaxin])
–> many major drug interactions
- Interacts with Statins, Ca Channel blockers, antiretrovirals, colchicine, carbamazepine
- -combination with statins (increase serum statins, risk of myopathy, rhabdomyolysis, hepatitis)
- skin rash (urticaria, bullous eruptions, eczema, SJS)
- GI distress (esp. Erythomycin)
Azithromycin is most common well-tolerated macrolides (rare GI effects) - the risk of QT prolongation (cautions with pts with Dysrhythmias)
Tetracyclines: MOA/indications
Tetracycline/Doxycycline
MOA: inhibit protein synthesis by reversibly binding to the 30S subunit of the bacterial ribosome
- -Work against gm +/- and atypical
- -BacterioSTATIC
Indications:
- Doxy 1st line for Rocky Mountain spotted fever (RMSF) and Lyme dz
- CAP (2nd line)
- Mild to moderate respiratory tract infection (atypical), AECB, skin (acne, rosacea)
Tetracyclines: Cautions/CI/ADRs
- Avoid in pregnancy (Cat D), lactation, and children < 8 years old
- d/t teeth discoloring
- Avoid antacids as they are Inactivated by Ca+ and aluminum
ADRs:
- nephrotoxic
- hepatotoxicity
- photosensitivity (use hat sunblock)
Tetracyclines: Education
- Take with a full glass of water
-
Do not take with milk or milk products (binds to calcium)
- Best to take 1 hr before or 2 hrs after a meal
- or Take on an empty stomach
- Can cause stomach upset/esophagitis
- May decrease effectiveness of oral contraceptives
- Wear sunglasses, hats, sunblock when expose
Fluoroquinolones: MOA
Ciprofloxacin, Levofloxacin
MOA: interferes with bacterial enzymes required for the synthesis of bacterial DNA - breakage of DNA strands/Inhibit DNA synthesis
Fluoroquinolones: INDICATIONS
Complicated severe infections
- pyelonephritis (1st line)
- complicated UTIs
- CAP (3rd line) -
- after tetracycline (2nd line)
Fluoroquinolones: cautions/CIs/ADRs
- BBW:
- risk of tendon rupture and tendonitis
- risk fo aortic dissection
- risk of QT prolongation (avoid use with other QT-prolonging drugs like amiodarone, macrolides, TCA),
-dizziness, confusion, seizures, photosensitivity
- high risk of superinfection (C.Diff, candida)
- Increasing resistance - not to be used for minor uncomplicated infections
Contraindications:
- children < 18 (unless pyelonephritis, anthrax, allergies to other meds)
- pregnancy (Cat C) and lactation
- elderly
- hx of HTN, aneurysm, CVD
- myasthenia gravis
Sulfonamides/Trimethoprim (SMX/TMP) - MOA
Sulfonamides inhibit folic acid synthesis
Trimethoprim inhibits DNA synthesis
Excellent Broad spectrum, both gm +/-
Sulfamethoxazole and Trimethoprim (Bactrim) Indications
- UTI
-Community-acquired MRSA
-excellent gram - (E.coli, Klebsiella, H. flu) and gram + (staph and strep) coverage,
-pneumocystis, chlamydia
Sulfonamides and Trimethoprim: Cautions/CIs
Common hypersensitivity reactions:
- rash, fever, SJS (more common in HIV + patients)
Contraindications
- pregnancy (anti-folate effects) - esp in 1st trimester
- pediatrics < 2 months old (risk of hyperbilirubinemia)
-Avoid concomitant** administration with **K+ sparing drugs (triamterene, ACE, ARB) d/t Hyperkalemia (reduces K+ excretion)
-Avoid with warfarin (increase risk of bleeding, increase INR)
Nitrofurantoin: MOA/Indications
•Multifactorial MOA
•Bacteriostatic in low concentrations, Bactericidal in higher concentrations
-May inhibit acetyl coenzymes --> interferes with bacterial protein synthesis, cell wall synthesis, and aerobic energy metabolism Indications:
Indication:
- uncomplicated UTI (1st line),
- Not indicated in complicated infections/pyelonephritis
Nitrofurantoin ADRs
neuropathy, pulmonary reactions
Metronidazole [Flagyl]: MOA/Indications
MOA: Damage DNA structure – causing strand breakage, inhibition of protein synthesis, and cell death
- BROAD-spectrum (gm +/- anaerobic bacteria and parasitic: protozoans, fungal)
- Bacteriostatic
Indications:
- C. diff,
- bacterial vaginosis,
- stool infections,
- trichomoniasis (think below the belt infections), giardia
Metronidazole ADRs
- metallic taste
- dark urine
- hepatotoxicity
- superinfections (rare)
Metronidazole: cautions/CIs/pt education
- AVOID in the 1st trimester of pregnancy
- take with food
- Avoid ETOH during and for 2 days after tx (can cause disulfiram rx: N/V, H/A, flushing, dizziness, chest and abdominal discomfort)
- BBW: potentially carcinogenic
Tinidazole: MOA/indications
MOA: thought to cause cytotoxicity by damaging DNA and preventing DNA synthesis
- newer, more expensive
Indications: bacterial vaginosis, trichomoniasis - more for fungal, protozoan, parasitic infections - not as much bacterial
Tinidazole cautions/CIs
- Avoid in pregnancy
- BBW: potentially carcinogenic
Impetigo treatment
- Mupirocin (Bactroban; monoxycarbolic acid class) topically 3x/day for 5-14 days for up to 5 lesions
- Cephalexin [Keflex] or Cefadroxil [Duricef] (PO, a cephalosporin 1st gen) if there are 5 or more impetigo lesions
Oral medication options for SKIN LESIONS
- Cephalosporin 1st gen (Cephalexin, Cefadroxil), Augmentin, Bactrim (TMJ, SMZ)
- moderate to severe impetigo (5 or more lesions), boils, perianal strep, cellulitis
- CBD (cephalexin, bactrim, doxycycline)
- Dicloxacillin If MRSA skin infection is suspected
Oral Candidiasis treatment
Antifungal:
- nystatin or clotrimazole lozenges
Antifungal agents
- used to treat vulvovaginal yeast infections
- Topical
- Miconazole and clotrimazole
- Oral
- Fluconazole oral (systemic) x 1 dose
Topical treatment of tinea pedis (athlete’s foot) or tinea corporis (ringworm)
- thin layer of terbinafine, miconazole, ketoconazole, clotrimazole
- use BID
- wash hands well before and after use
Topical HERPES simplex (Shingles) treatment
- topical acyclovir (zovirax) , or penciclovir (denavir, and OTC docosanol (Abreva))
- start as soon as possible
Fluconazole (Oral) MOA/indications
- interferes with fungal CYP 450 activity
- inhibits cell membrane formation
- broad-spectrum, antifungal, systemic effect
Indications: candidiasis (vaginal, oropharyngeal, esophageal)
Fluconazole: cautions/CIs
-Hard on liver –> Monitor hepatic function
- CYP 3A4 and 2C9 inhibitor
-QT prolongation –> check EKG
-Avoid in pregnancy
Itraconazole MOA/indications
- interferes with fungal CYPE 450 activity
- inhibits cell membrane formation
- broad-spectrum systemic treatment
Indications: onychomycosis (nail fungus) but Terbinafine/Ciclopirox (topical) is first-line for Onychomycosis
Itraconazole cautions/CIs
- hard on the liver
- QT prolongation
- avoid in pregnancy
- BBW: avoid in patients with HF/myocardial dysfunction
Terbinafine/Ciclopirox (topical) : MOA/indications
- synthetic allylamine derivative
- inhibits squalene eposidase enzyme (a key enzyme in sterol biosynthesis in fungi
- results in fungal cell death
- metabolized by CYP450
Indication: onychomycosis (1st line)
- Off label: extensive tinea fungal infection
Terbinafine cautions/CIs
- arrhythmias (think QT)
- hepatic impairment
- avoid in pregnancy
Terbinafine ADRs
- hepatotoxicity hepatic failure
- blood dyscrasias
Amoxicillin
-
Broad spectrum beta-lactam penicillin
- both Gm +/- but more effective against gram (-)
- Bactericidal
- PO 2-3x/day
- Against
- Group A strep, S. pneumo, staph, H. influenza
Amoxicillin/Clavulanic acid [Augmentin]
For otitis media, sinusitis, lower RI, skin (cellulitis), bites
