Penicillin Antibiotics

• Below are drug classifications with associated prototypes, indications, mechanisms of action, considerations, and teaching points

Penicillin (beta lactam)

• Prototypes include penicillin V (PO), penicillin G (IV), amoxicillin (PO), and piperacillin/tazobactam (IV)
• Treats Streptococcal, Pneumococcal, and Staphylococcal infections
• Inhibits bacteria by interfering with protein synthesis needed for cellular walls, leading to cell breakdown
• Take with a full glass of water and avoid citrus (grapefruit) juice
• Best absorbed orally on an empty stomach or with food if stomach upset
• High doses can cause bleeding abnormalities, elevated BUN, creatinine, AST, and ALT
• Oral contraceptives may be less effective
• Common side effects include nausea, vomiting, diarrhea, epigastric distress, and black hairy tongue
• Monitor for Clostridium Difficile, candida, and hyperkalemia
• Hypersensitivity reactions include rash, urticaria, laryngeal edema, and anaphylaxis
• Stop medication if an allergic reaction occurs and treat anaphylaxis with epinephrine and airway management

Cephalosporin (beta lactam)

• Prototypes include cephalexin (1st gen), cefazolin (1st gen), cefprozil (2nd gen), ceftriaxone (3rd gen), cefepime (4th gen), and ceftolozane (5th gen)
• Treats respiratory and skin-structure infections, bone infections, genitourinary infections, otitis media, and community-acquired infections
• Bactericidal, acting similarly to penicillin by interfering with cell wall synthesis
• Dosage adjustment is needed for renal impairment, monitoring BUN and creatinine
• Use with caution in patients with seizure disorder
• Side effects include nausea, vomiting, diarrhea, and epigastric distress
• Monitor for rash and Clostridium Difficile
• May increase INR and bleeding risk
• Cephalosporins are grouped by "generations"

Carbapenem (beta lactam)

• Prototypes include imipenem (IV infusion only) and meropenem
• Carbapenems treat life-threatening, multidrug-resistant infections due to their broad spectrum of activity
• Also treats gram + and gram - infections and is useful for complex hospital-acquired infections in compromised patients
• Bactericidal, inhibiting bacterial cell wall synthesis
• Dosage adjustment with renal impairment, use with caution in seizure disorder
• Side effects are similar to cephalosporins
• Administer IV without regard to food, but give with food if GI distress occurs
• Reconstitute drug with sterile water or normal saline and shake well until dissolved; inject into large vein or free-flowing IV solution over 3-5 minutes
• There is a drug interaction with anticoagulants
• Patients who consume cephalosporins while drinking alcoholic beverages may experience disulfiram-like reactions
• May enter breastmilk and may alter bowel flora of the infant

Monobactam (beta lactam)

• Prototype: aztreonam (IV, IM or inhalation)
• Narrow spectrum antibacterial medications primarily used to treat gram-negative bacteria such as Pseudomonas aeruginosa
• Bactericidal, inhibiting bacterial cell wall synthesis
• Watch for allergies (rash) and superinfections; coagulation abnormalities are possible
• Side effects are similar to GI symptoms

Sulfonamides

• Prototype: trimethoprim-sulfamethoxazole (oral and IV)
• Treats urinary tract infections, otitis media, acute exacerbation of chronic bronchitis, and travelers' diarrhea
• Bacteriostatic inhibitor of growth against a wide spectrum of gram + and gram - pathogens by inhibiting bacterial synthesis of folic acid
• Common allergic reactions include rash or other hypersensitivity reactions; dosage adjustment for renal impairment is needed
• Do not administer to women in their last trimester of pregnancy or to lactating women and to children under 2 months of age due to the risk of kernicterus
• Increase fluid intake to prevent crystalluria

Fluoroquinolones

• Prototype: levofloxacin (PO, IV, ophthalmic)
• Treats pneumonia or complicated skin or urinary tract infections
• Synthetic antibacterial medication inhibits bacterial DNA replication and are bactericidal
• Administer PO with 8 oz of water and use cautiously with cardiac antidysrhythmics (e.g. digoxin), oral antidiabetics, and oral anticoagulants
• Can cause photosensitivity
• Contraindications: women no sun, baby, breastfeeding, drink water
• Oral: give with plenty of fluids (to prevent crystalluria & promote absorption), administer 2 hours before or after meals, antacid, or iron, calcium or zinc
• BOXED WARNING: Tendonitis, tendon rupture, peripheral neuropathy, CNS effects, or muscle weakness in patients with Myasthenia Gravis
• Side effects: GI upset, hypersensitivity, photosensitivity

Macrolides

• Prototypes include erythromycin (PO, IV, topical, ophthalmic) and azithromycin (PO, IV, ophthalmic)
• Often used for respiratory infections, otitis media, pelvic inflammatory infections, and chlamydia (given to neonates)
• Macrolides inhibit RNA protein synthesis & suppress reproduction of a broad spectrum of bacteria and are bacteriostatic
• Report h/o prolonged QT syndrome
• Side effects: GI upset, hypersensitivity, photosensitivity, drowsiness
• Discontinue immediately if: -QT prolongation or dysrhythmias (assess for chest pain) -Signs of liver damage or jaundice -Onset or worsening of myasthenia gravis

Aminoglycosides

• Prototypes: streptomycin (IM) and gentamicin (IM, IV, topical, ophthalmic)
• Streptomycin is for streptococcal endocarditis and a second line treatment for tuberculosis; neomycin treats hepatic encephalopathy as adjunct therapy to lower ammonia levels and is also used as a bowel prep for colon procedures
• Aminoglycosides are bactericidal and bind with the area of the ribosome known as the 30S subunit, inhibiting protein synthesis in the cell wall and resulting in bacterial death. They are a broad spectrum
• Poorly absorbed in the GI tract; therefore, the majority are given IV or IM.
• Blood peak and trough levels should be performed to titrate a safe dose for each patient.
• Side/Adverse effects: GI upset, rash, report diarrhea immediately
• Drink plenty of water
• Safety (administer cautiously): -Nephrotoxicity (monitor renal function closely: BUN, creatinine, GFR) -Neurotoxicity esp. with renal impairment (assess peripheral numbness). Can result in respiratory paralysis if given soon after anesthesia or muscle relaxant -Ototoxicity, especially if administere with a loop diuretic (vertigo, tinnitus, hearing loss)

Tetracycline

• Prototype: Tetracycline (PO)
• Broad spectrum, but limited due to the significance of SE
• Tetracycline penetrate the bacterial cell wall and bind to the 30S ribosome, inhibiting the protein synthesis require to make the cellular wall
• Side/Adverse Effects: GI symptoms, c diff, photosensitivity, oral candidiasis
• PO administration: -give with a full glass of water on an empty stomach at least 1 hr before or 2 hrs after a meal for best absorption -Give drug at least 1 hour before laying down to prevent esophageal irritation or ulceration
• Do not give with dairy products, antacids or iron as effectiveness is↓
• Watch for intracranial hypertension (HA, burry vision, diplopia, vision loss)
• ↓ effectiveness of oral contraceptives
• Use caution with renal or hepatic impairment
• Permanent tooth discoloration if given to patients less than 8 y/o (same reason not to give in pregnancy)

Miscellaneous Antibacterials: Glycopeptides

• Prototype: vancomycin (PO, IV)
• Active against gram + bacteria. Vancomycin is commonly used to treat serious or severe infections when other antibiotics are ineffective or contraindicated, including those caused by MRSA.
• Inhibit bacterial cell wall synthesis.
• Blood trough levels (15-20 mg/L) should be performed to titrate a safe dose for each patient
• Ototoxicity (monitor for tinnitus, hearing loss, vertigo)
• Safety: -Nephrotoxicity
• Route: IV but PO for C-diff. It is poorly absorbed from the GI tract, so it must be given by IV to treat a systemic infection. Oral vancomycin, on the other hand, is used to treat antibiotic associated clostridium difficile (C-diff).
• IV should be administered in a diluted solution over a period of 60 minutes or more to avoid rapid-infusion-related reactions
• Red-man syndrome can occur if drug is infused too rapidly (maculopapular rash on face, neck, trunk, and limbs, pruritus & hypotension caused by histamine release). -Stop infusion and contact provider. Prepare to administer diphenhydramine 50mg IV or PO. Monitor BP closely; IV fluids and/or vasopressors may be required if hypotensive. Infusion may be resumed at a slower rate after rash and itching resolve.
• Dosage adjustment is required for renal impairment
• C-diff can occur up to 2 months after therapy ends