Pharmacology: Antibiotics & Anti-infectives

antiobiotic

substance that can weaken or destroy organisms; generally, refers to bacteria

pathogen

a disease producing agent or organism

culture & sensitivity

• sample is grown to identify pathogenic microorganism and identify what medication can be used to treat infection

• used to identify bacteria and determine which antibiotic it is susceptible to~ guides prescribers on what antibiotic to prescribe

gram stain

• method of identifying bacteria using crystal violet staining

• gram positive: retains only violet/purple stain

• gram negative: retains only pink/red stain

anti-infective medications

antibiotic; antiviral; antifungal

antibiotic

generally used to describe anti-bacterial medications~ can be oral (PO), intravenous (IV) or topical

antiviral

agents that act against viral microbes

antifungal

kills or inhibits growth of fungi

bacteria

• single celled microorganisms that do not contain a nucleus, some of which cause disease

• classified by: shape, gram positive and gram negative (G+ or G-), relationship with oxygen (anaerobe v aerobe), flagella or pili (fimbriae)

Gram positive~ bacterial cell wall structure

cell wall retains crystal violet stain; has a simpler cell wall structure

Gram Negative~ bacterial cell wall structure

• cell wall does not retain crystal violet stain (only pink/red [safranin] stain) due to more complex cell wall structure

• gram negative bacteria less susceptible to antibiotics due to this more complex cell wall structure as many antiobiotics work on the cell wall

antibiotic classes

• divided into classes based on their chemical makeup and mechanism of action (MOA)

• broad spectrum: effective against many types of bacteria

• narrow spectrum: effective against limited types of bacteria

Nursing process for antibiotic administration

• collect baseline data; history; allergies; current meds; physical assessment + vs; psychosocial assessment

• educate pt about their prescribed course of treatment~ implementation

• administer medication per protocol~ implementation

• monitor for s/e and response to treatment~ evaluation

Nausea, Vomiting, Diarrhea (N/V/D)

considered the big three associated with antimicrobial therapy

Allergies & anaphylaxis

allergic reactions from mild rash to fatal anaphylaxis can occur

nephrotoxicity

toxic effects to the kidneys

hepatotoxicity

toxic effects to the liver

ototoxicity

damage to 8th cranial nerve; manifests as ringing in ears, dizziness, hearing loss~ agitation

photosensitivity

increased risk for sun damage to integumentary system

secondary infection

destruction of normal flora can allow another organism the opportunity for growth

blood dyscrasias

loss of clotting ability

antibiotic mechanisms of action

• cell wall or membrane synthesis or function

• inhibit protein synthesis

• metabolic pathway inhibitors

• nucleic acid synthesis

cell wall or membrane synthesis or function

inhibits cell wall synthesis~ Penicillins; Cephalosporins; Glycopeptides (Vancomycin)

inhibit protein synthesis

affect on ribosomes; ribosomes used for protein synthesis~ Macrolides; Lincosamides; Aminoglycosides; Tetracyclines

metabolic pathway inhibitors

inhibit production of folate~ sulfonamides

nucleic acid synthesis inhibitors

affect RNA/DNA of cell~ Quinolones/Fluoroquinolones; Metronidazole

Penicillins

• MOA inhibits cell wall synthesis; beta-lactam ring interferes with normal cell wall synthesis

• penicillin was the first antibiotic developed

• ex: Penicillin (1st gen; G+), amoxicillin, ampicillin, methicillin

• indications: G+ and G-

• common SE: NVD; if given IM; pain at injection site; serious SE: seizures, Clostridium difficile

• Allergic reaction to penicillin: rash, fever, inflammatory conditions, may progress to anaphylaxis~ if allergic to one penicillin, allergic to all penicillins

• there are 4 generations from the simplest 1st generation to the most complex 4th generation (given IV). Over time, more resistant bacteria required development of more sophisticated antibiotics.

Cephalosporins

• MOA: inhibits cell wall synthesis; beta-lactam ring interferes with normal cell wall synthesis

• ex: cephalexin, cefazolin, ceftriaxone

• indications: G+ and G-

• common SE: NVD; if given IM, pain at injection site; serious SE: seizures, Clostridium difficile, Stevens-Johnson Syndrome

• 4 generations

• if allergic to penicillin, likely allergic to cephalosporins

• no alcohol (may induce a disulfiram type reaction; severe nausea, vomiting, flushing, vertigo, hypotension, tachycardia)

Glycopeptides

• MOA: inhibit cell wall synthesis

• ex: Vancomycin

• indications: G+ ~ serious and potentially life-threatening infections

• common SE: NV; nephrotoxicity, phlebitis if IV

• serious SE: Red-man syndrome (with IV admin; flushing; hypotension; tachycardia- anaphylactoid type reaction); nephrotoxicity; ototoxicity, neutropenia

• paired with Metronidazole to treat Clostridium difficile

Aminoglycosides

• inhibits protein synthesis

• Gentamicin, streptomycin

• indications: G-

• SE: NVD; ataxia (impaired coordination); ototoxicity (report ringing in ears immediately); nephrotoxicity

• serious: none

Macrolides

• inhibits protein synthesis

• ex: Erythromycin, Azithromycin (Z-Pak)

• indications: G+

• common: NVD; abdominal pain

• serious: hepatotoxicity, Clostridium difficile; Stevens-Johnson Syndrome

• often the choice for people with penicillin allergies

Tetracyclines

• inhibits protein syntehsis

• ex: Tetracycline, doxycycline

• common: NVD, dizziness, vestibular reactions, photosensitivity

• serious: hepatotoxicity, Clostridium difficile, Stevens-Johnson syndrome

• never use in pregnancy or childhood~ causes skeletal growth retardation in infants

Lincosamides

• inhibits protein synthesis

• ex: Clindamycin

• indications: G+ anaerobes

• common: NVD

• serious: Clostridium difficile (high risk); Stevens-johnson syndrome; hypersensitivity/rash

Sulfonamides

• inhibits Folate production~ unable to synthesize

• ex: Trimethoprim/sulfamethoxazole (Bactrim, Septra) ~ combination of two antibiotics results in higher efficacy

• indications: G+ and G-; commonly used for UTIs

• common: NVD; rash; photosensitivity

• serious: Clostridium difficile, hepatotoxicity, stevens-johnson syndrome

Quinolones/Fluoroquinolones

• MOA: nucleic acid synthesis inhibitors (DNA/RNA)

• ex: Ciprofloxacin, levofloxacin

• indications: G+ and G-; broad spectrum

• common: NVD, dizziness, headache, insomnia, photosensitivity

• serious: seizures, increase intracranial pressure, stevens-johnson syndrome, Clostridium difficile, hepatotoxicity

• black box warning: tendon problem, nerve dmg, aortic aneurysm or dissection, psychiatric side effects

Metronidazole (Flagyl)

• MOA: nucleic acid synthesis inhibitors (DNA/RNA)

• antibiotic (for bacteria) PLUS antiprotozoal/amoebicidal

• indications: G- and G+; C-diff, giardia

• common: abdominal pain, nausea, diarrhea, anorexia, dizziness, headache, unpleasant taste

• serious: SJS

• Metronidazole + Vancomycin used to treat C-diff

Multi-Drug Resistant Organisms- MDRO | AMR

• MDRO: microorganisms, predominately bacteria, resistant to one or more classes of bacteria

• AMR: Antimicrobial Resistance

• ex: MSRA (methicillin-resistant staphylococcus aureus); ESBL (extended spectrum beta-lactamases); C.diff

Factors contributing to AMR Antimicrobial Resistance MDROs

• common unnecessary use of antibiotics (often for viral infections); not completing full course of antibiotics; use in animals for prophylaxis or as growth promoters; inadequate infection control practices

• few new antibiotics are being developed; money towards meds used regularly v one time

Antibiotic Resistance Beta-Lactam antibiotic

• bacterial resistance mechanism = secretion of beta-lactamase enzyme that inactivates the beta-lactam ring of the antibiotic

• to counter this, beta-lactam ABX paired with a beta-lactamase inhibitor

Beta lactam + beta lactamase inhibitor ABX

• Amoxicillin + clavulanic acid = Augmentin

• Ampicillin + sulbactam = Unasyn

• Piperacillin + tazobactam = Zosyn

Antifungal medications

• used to treat topical/vaginal infections or systemic infections

• MOA: most work by affecting the integrity of the cell wall

Antifungal topical~ mostly OTC

• prescription topical- Nystatin (Nystop) Powder or cream

• OTC topicals- Terbinafine (Lamisil AT), Butenafine (Lotrimin Ultra), Miconazole (Monistat)- vagina, Clotrimazole (Lotrimin AF)

Antivirals

acyclovir, valacyclovir, tamiflu, zidovudine

Acyclovir

• for Herpes Simplex I and II

• common se: NVD, dizziness, headaches

Valacyclovir

• for Herpes zoster (Shingles)

• common se: headache, nausea

Tamiflu (oseltamivir)

• for influenza

• PO (must be started within 48 hours of sx onset)~ catch early

• common se: none

Zidovudine (AZT, Retrovir)

• for HIV, also reduces maternal to fetal transmission

• common se: headache, weakness, abdominal pain, ND, anemia

alcohol

kills most bacteria on surfaces; disinfection of instruments; skin prep for injections

hydrogen peroxide

mild antiseptic used for minor cuts, scrapes; short-term use only (cytotoxic)

povidone-iodine (Betadine)

broad antimicrobial spectrum, preoperative scrub, postoperative antiseptic, wounds, catheterization procedures

chlorhexadine

kills bacteria, spores, fungi and viruses. used for surgical prep, wound cleansing, hand washing

• not for genitals; do not swallow or get in eyes, ears, nose

patient education

• perform hand hygiene often

• take antibiotics only when necessary

• take entire course of antibiotic medication

• education pt on se and observe for same

• watch for episodes of diarrhea; if 3 or more episodes of diarrhea in 24 hours should be evaluated for Clostridium difficile

• stay current on vaccinations