Drugs Used to Treat Infections
Antimicrobial Agents
Types of Antimicrobial Agents:
Antibiotics classified by target pathogen:
Antibacterial: Treats bacteria.
Antifungal: Treats fungi.
Antiviral: Treats viruses.
Chemical Families:
Penicillins
Tetracyclines
Aminoglycosides
Culture and sensitivity tests determine the causative pathogens.
Other considerations for use:
Toxicity potential to the patient
Clinical judgement
Previous infection treatments
Reactions to antibiotics
Selection and Assessment
Choosing Antibiotics:
Based on pathogen sensitivity and patient toxicity considerations.
Utilize culture and sensitivity tests for appropriate selections.
Consider empirical treatment and prophylactic antibiotics for infection prevention.
Nursing Assessment
Before Therapy:
Assess current infection history & medication history.
Conduct a physical examination and psychosocial evaluation.
During Therapy:
Adverse Effects Monitoring:
Nausea, Vomiting, Diarrhea (the "big three"):
Assess relation to antibiotic use, hydration status, report diarrhea, abdominal pain.
Secondary Infections:
Watch for oral infections, lesions, or itching in vaginal, anal areas.
Can produce severe life-threatening diarrhea.
Allergies and Anaphylaxis:
Mild to fatal, within 30 minutes after administration to days after therapy.
Anaphylaxis, laryngeal edema, shoch, dyspnea, skin reactions.
Determine if allergies (skin rash, edema, dyspnea) or GI symptoms.
Nephrotoxicity:
Increasing BUN/creatinine levels, decreasing urine output, changes in UA.
Hepatotoxicity:
Check for preexisting hepatic disease, abnormal liver function tests.
Ototoxicity:
Damage to eighth cranial nerve, can lead to hearing loss
Blood Dyscrasias:
Report hematological symptoms.
Additional Notes:
Laboratory test values indicating infection: CBC, ESR, BUN, AST, ALT, GGT, C-reactive protein, electrolytes.
American Heart Association recommends prophylactic antibiotics for patients with certain cardiac conditions.
Nephrotoxicity is evidenced by increasing BUN and creatinine, decreased urine output.
Ototoxicity is damage to the eighth cranial nerve, primarily by aminoglycosides—hearing loss, dizziness, tinnitus.
Photosensitivity occurs with certain antibiotics.
Implementation Strategies
Patient Care During Therapy:
Infection Control: Ensure proper transmission precautions.
Secondary Infections: Notify healthcare provider if infection develops.
Monitor IV Therapy: Check for phlebitis and instability of medications.
Scheduling: Administer medications on time; clarify food interactions.
Hydration and Nutrition: Manage nausea and adjust medication routes if necessary.
Nausea, vomiting, diarrhea: Give with food if possible, or healthcare provider can switch to parenteral.
Monitoring Adverse Effects:
Nephrotoxicity: Monitor BUN/creatine, I&O; report declining urine output <30 mL/hr.
Hepatotoxicity: Monitor labs, observe for anorexia, nausea, vomiting, jaundice, etc.
Ototoxicity: Report hearing impairment, dizziness, or tinnitus.
Blood dyscrasias: Monitor and report sore throat, fatigue, elevated temperature, skin hemorrhages, and bruises.
Allergies/Anaphylaxis: Monitor patients with allergies, asthma, rhinitis, or taking multiple meds for allergic response; watch for 20 to 30 minutes after administration.
Photosensitivity Management: Advise use of sunscreen and avoidance of UV exposure.
Patient Education
Key Instructions for Patients:
Emphasize the importance of rest, hydration, and proper nutrition.
Discuss personal hygiene and precautions for STI treatments.
Refrain from sexual intercourse during therapy for STIs.
Educate on common adverse effects and proper reporting.
Urgent need to finish the full course of antimicrobials to avoid resistance.
Drug Classes and Their Actions
Examples of Antibiotics:
Aminoglycosides:
Action: Inhibit protein synthesis.
Uses: Effective against gram-negative organisms that cause urinary infections, meningitis, wound infections, septicemia.
Serious Adverse Effects: Ototoxicity, nephrotoxicity.
Do not give within 72 hours of skeletal muscle relaxants used with anesthesia.
Aminoglycosides stop organisms from multiplying and spreading.
Carbapenems:
Action: Inhibit bacterial cell wall synthesis; potent broad-spectrum agents resistant to beta-lactamase enzymes secreted by bacteria.
Uses: Treat severe infections by multidrug-resistant organisms.
Adverse Effects: Hypersensitivity; severe diarrhea, if contains blood may be indication of pseudomembranous colitis; dizziness, confusion, seizures.
Effective against intraabdominal infections and pelvic sepsis.
Cilastatin is given with imipenem (Primaxin) to prevent the inactivation of imipenem by a renal enzyme.
Cilastatin is not an antibiotic.
Cephalosporins:
Action: Related to penicillins; inhibit bacterial cell wall synthesis; divided into groups.
Uses: Treats UTI, respiratory tract infections, abdominal infections, bacteremia, meningitis, osteomyelitis; ceftaroline may treat MRSA, VRSA.
Common Adverse Effects: Diarrhea, electrolyte imbalances.
Serious Adverse Effects: Secondary infections; hepatotoxicity; nephrotoxicity; hypoprothrombinemia.
First-generation agents are effective against gram-positive microorganisms.
Second- and third-generation agents have increased activity against gram-negative organisms.
Fourth-generation cephalosporins are broad-spectrum agents.
Glycopeptides:
Action: Prevent synthesis of bacterial cell walls.
Uses
Dalbavancin is used in treatment of adult patients with acute bacterial skin and skin structure infections.
Oritavancin, telavancin, vancomycin.
Therapeutic Outcome: Elimination of bacterial infection.
Serious Adverse Effects: Ototoxicity, nephrotoxicity, Q-T interval prolongation, coagulation, hepatic effects, secondary infections
Glycylcycline:
Drug: Tigecycline (Tygacil)
Action: Binds to 30S ribosome, preventing protein synthesis; bacteriostatic
Use: Treat broad-spectrum gram-positive, gram-negative, and anaerobic infections, MRSA
Common Adverse Effect: Gastric irritation
Serious Adverse Effects: Severe diarrhea; photosensitivity
New family of antibiotics; tigecycline first drug
Used in complicated skin infections (MRSA, MSSA), intraabdominal infections.
Do not administer to those younger than age 18 because of the interference with tooth development.
Macrolides
Action: Inhibit protein synthesis, bacteriostatic and bactericidal
Uses: Treat respiratory, GI tract, skin, and soft-tissue infections
Common Adverse Effect: Gastric irritation
Serious Adverse Effects: Severe diarrhea, thrombophlebitis
Usually the second choice when penicillins, cephalosporins, and tetracyclines are contraindicated.
Oxazolidinones
Drug: Linezolid (Zyvox)
Action: Inhibits protein synthesis in bacterial cells, bactericidal, and bacteriostatic.
Use: Treat serious or life-threatening infections caused by gram-positive organisms.
Common Adverse Effects: Gastric irritation, headaches.
Serious Adverse Effects: Severe diarrhea, bone marrow suppression, secondary infections, lactic acidosis, seizures, visual neuropathy.
New class of antimicrobial agents; linezolid is first drug.
May be used for vancomycin-resistant E. faecium (VRE), MRSA, and MSSA; effective against gram-positive organisms only.
Interacts with MAOIs and other serotonergic agents.
Penicillins
Action: Inhibit cell wall synthesis, penicillinase-resistant penicillins.
Uses: Treat middle ear infections, pneumonia, meningitis, UTIs, syphilis, gonorrhea.
Common Adverse Effects: Diarrhea, electrolyte imbalance
Serious Adverse Effects: Hepatotoxicity, nephrotoxicity, hyperkalemia, or hypernatremia.
Penicillinase is the enzyme that bacteria produce to destroy the antibacterial activity of penicillins.
May interfere with contraceptive activity of oral contraceptives.
Counsel patient to use additional method.
Quinolones:
Action: Subclass known as fluoroquinolones; inhibit activity of DNA gyrase, an enzyme needed for replication of bacteria.
Uses: Effective against gram-positive and gram-negative bacteria.
Common Adverse Effects: Nausea, vomiting, diarrhea, discomfort, dizziness, lightheadedness.
Serious Adverse Effects: Photosensitivity, rash, nephrotoxicity, neurologic effects, hepatotoxicity.
Should not be prescribed for patients younger than 18 years; has resulted in an increased incidence of musculoskeletal disorders.
Risk of musculoskeletal disorders in patients older than 60 is increased in patients using corticosteroids.
Animal studies have demonstrated teratogenic effects.
Birth defects or abnormalities.
Levofloxacin used with caution in older patients with long QT syndrome, hypokalemia, or taking certain antiarrhythmic medications.
Streptogramins
Drug: Quinupristin-dalfopristin (Synercid)
Action: Inhibits protein synthesis in bacterial cells
Uses: Treatment of vancomycin-resistant E. faecium (VRE), MRSA
Common Adverse Effects: Pain, infusion site inflammation, nausea, vomiting, diarrhea, anorexia, abdominal cramps
Serious Adverse Effects: Hepatotoxicity, arthralgia, myalgia
Numerous serious drug interactions
New class developed from pristinamycin
Important for treatment of vancomycin-resistant bacteria; reserved for cases in which other antibiotics are not effective
Sulfonamides:
Action: Inhibit biosynthesis of folic acid resulting in cell death.
Uses: Treats UTIs and otitis media, traveler’s diarrhea, chronic diarrhea, prevention and treatment of Pneumocystis jiroveci in immunocompromised patients.
Common Adverse Effects: Nausea, vomiting, diarrhea, anorexia.
Serious Adverse Effects:
Rash, pruritus, photosensitivity, hematologic reactions, neurologic CNS effects.
Notify prescriber if rash or pruritus develops.
Crystal formation in urinary tract if patient is dehydrated.
Work fast, usually after one or two doses.
Used prophylactically in patients susceptible to streptococcal infection or rhematic fever when penicillin is contraindicated.
Tetracyclines:
Action: Inhibit protein synthesis by bacterial cells.
Uses: Treat STIs, UTIs, upper respiratory tract infections, pneumonia, and meningitis when penicillin is contraindicated.
Common Adverse Effects: Nausea, vomiting, diarrhea, anorexia, abdominal cramps, diarrhea.
Serious Adverse Effect: Photosensitivity.
Can stain teeth; not recommended for children younger than age 8 or pregnant women.
Miscellaneous Antibiotics:
Aztreonam (Azactam): Inhibits cell wall synthesis, monobactams
Clindamycin (Cleocin): Inhibits protein synthesis
Daptomycin (Cubicin)
Cyclic lipopeptide, binds to bacterial membranes and causes rapid depolarization
Serious adverse effects: diarrhea, muscle pain
Used only for cases of vancomycin resistance; may also cause skeletal muscle weakness and pain.
Metronidazole (Flagyl): Bactericidal, trichomonacidal, and protozoacidal activity
Tinidazole (Tindamax)
Similar to metronidazole
Primary therapeutic outcome: elimination of parasitic infection
Antitubercular Agents
Drug: Ethambutol (Myambutol)
Action: Alter cellular RNA synthesis and phosphate metabolism
Use: Treatment of tuberculosis
Common Adverse Effects: Nausea, vomiting, anorexia, abdominal cramps
Serious Adverse Effects: Confusion, hallucination, blurred vision, red-green vision changes
Major problem with toxicity can occur.
Treatment can last 6 months.
Drug: Isoniazid (INH, Nydrazid)
Action: Disrupts the cell wall and inhibits replication of tuberculosis bacteria
Use: Treats and prevents tuberculosis
Common Adverse Effects: Nausea, vomiting
Serious Adverse Effects: Hepatotoxicity, tingling, numbness of hands and feet, dizziness, ataxia
Adverse effects are dose related; concurrent use of pyridoxine usually prevent symptoms.
Drug: Rifampin (Rifadin)
Action: Prevents RNA synthesis by inhibiting DNA-dependent RNA polymerase
Use: Eliminates meningococci and H. influenzae type b (Hib) from asymptomatic carriers
Common Adverse Effect: Reddish-orange secretions
Serious Adverse Effects: Nausea, vomiting, anorexia, abdominal cramps
Also used in combination with other agents to treat tuberculosis.
All three medications (ethambutol, isoniazid, rifampin) must be used in combination to prevent resistant organisms.
Drug: Pyrazinamide (Tebrazid)
Action: Lowers the pH of environment
Use: Treatment of tuberculosis; in combination with antitubercular agents
Common Adverse Effects: Nausea, vomiting, anorexia, arthralgia, myalgia
Serious Adverse Effect: Hepatotoxicity
Contraindicated in patients with acute gout.
Antifungal Agents
Topical Antifungal Agents
Action: Alter permeability of cell membranes, causing amino acids and electrolytes to leak out
Uses: Treat tinea pedis, tinea cruris, tinea corporis, tinea versicolor, Candida infections
Common and Serious Adverse Effects: Irritation, redness, swelling, blistering, oozing
Watch for secondary skin rashes
Systemic Antifungal Agents
Drug: Amphotericin B
Action: Fungistatic agent; disrupts cell membrane of fungal cells
Use: Treatment of systemic life-threatening fungal infection
Common Adverse Effects: Malaise, fever, chills, headache, nausea, vomiting, thrombophlebitis
Serious Adverse Effects: Nephrotoxicity, electrolyte imbalance
Dosage Forms: Amphotericin B with or without sodium desoxycholate (Fungizone IV), amphotericin B cholesteryl sulfate complex (Amphotec), amphotericin B lipid complex (Abelcet), amphotericin B liposomal (AmBisome).
Should not be used for noninvasive fungal infections such as thrush, vaginal candidiasis, esophageal candidiasis.
Drug: Fluconazole (Diflucan)
Action: Chemically related to ketoconazole and itraconazole; inhibits certain metabolic pathways in fungi
Uses: Treatment of meningitis, candidiasis, systemic candidiasis
Common Adverse Effects: Nausea, vomiting, diarrhea
Serious Adverse Effects: Rash, hepatotoxicity
Administered via IV and oral routes.
Drug: Griseofulvin microsize (Griseofulvin ultramicrosize, Grifulvin V)
Action: Stops cell division and new cell growth
Use: Treatment of ringworm
Common Adverse Effects: Nausea, vomiting, abdominal cramps
Serious Adverse Effects: Urticaria, rash, pruritus; photosensitivity; confusion, dizziness, secondary infections, nephrotoxicity, hepatotoxicity, hematologic
Available orally only
Treatment often required for several months
Drug: Itraconazole (Sporanox)
Action: Chemically related to fluconazole and ketoconazole; interferes with cell wall synthesis
Uses: Treatment of variety of infections such as candidiasis, histoplasmosis, blastomycosis
Common Adverse Effects: Nausea, vomiting
Serious Adverse Effects: Hepatotoxicity; heart failure; pruritus, rash
Numerous serious drug interactions
Do not administer to patients with a history of heart failure; has negative inotropic properties.
Has many drug interactions because it is a potent inhibitor of metabolizing enzymes in the liver.
Drug: Terbinafine (Lamisil)
Action: Inhibits squalene epoxidase, a key enzyme required for biosynthesis in fungi
Use: Treatment of onychomycosis of the toenail or fingernail
Serious adverse effects: Pruritus, rash, fever, chills; nephrotoxicity, hepatotoxicity; neutropenia, lymphopenia
Antiviral Agents
Drug: Acyclovir (Zovirax)
Action: Inhibits viral cell replication
Uses: Topically used to treat herpes genitalis; orally used to treat recurrent genital herpes; IV to treat herpes simplex types 1 and 2 in immunosuppressed patients
Serious Adverse Effects: Pruritus, rash, burning, hives, diaphoresis, nephrotoxicity, hypotension, confusion
Cautions with topical use to avoid spread
Drug: Famciclovir (Famvir)
Action: Prodrug of penciclovir; inhibits viral cell replication
Uses: Treatment of recurrent infections of genital herpes, acute herpes zoster
Common Adverse Effects: Nausea, vomiting, headache
Serious Adverse Effect: Confusion
Drug: Oseltamivir (Tamiflu)
Action: Inhibits neuraminidase
Use: Treats uncomplicated acute illness caused by influenza
Common Adverse Effects: Nausea, vomiting, cough, sore throat, fever, continuing symptoms
Drug: Ribavirin (Virazole, Rebetol, Ribasphere)
Action: Unknown
Uses: In combination with interferon alpha-2b to treat chronic hepatitis C, effective against DNA type viral families, inhibitory activity against RSV, influenza, parainfluenza
Common Adverse Effects: Rash, conjunctivitis
Serious Adverse Effects: Diminishing pulmonary function, anemia
Special technique for mixing and administering breathing treatment
Virazole is in aerosol form; Rebetol is in oral capsule and suspension form; Ribasphere is in oral tablets and capsules
Drug: Valacyclovir (Valtrex)
Action: Inhibits viral cell replication
Uses: Treats acute herpes zoster (shingles) and herpes labialis (cold sores and genital herpes)
Therapeutic Outcome: Elimination of symptoms of viral infection
Valacyclovir is a prodrug of acyclovir
Drug: Zanamivir (Relenza)
Action: Inhibits neuraminidase, an enzyme on the viral cell coat necessary for replication
Use: Uncomplicated acute illness from influenza
Serious Adverse Effects: Asthma, bronchospasm, diminishing pulmonary function, cough, sore throat, fever, continuing symptoms