Antibiotics
• Antibiotics are defined as:
Chemicals that inhibit specific bacteria
– Made in three ways:
o By living microorganisms
o By synthetic manufacture
o Through genetic engineering
Types of Antibiotics
• Bacteriostatic
– Those substances that prevent the growth of bacteria
• Bactericidal
– Those that kill bacteria directly
• Combination
Signs of Infection
• Fever
• Lethargy
• Slow-wave sleep induction
• Classic signs of inflammation (redness, swelling, heat, and pain)
Goal of Antibiotic Therapy
• Decrease the population of the invading bacteria to a point where the
human immune system can effectively deal with the invader
Selecting Treatment
• Identification of the causative organism
• Based on the culture report, an antibiotic is chosen that has been
known to be effective at treating the invading organism
Bacteria Classification
• Gram-positive
– The cell wall retains a stain or resists decolorization with alcohol
• Gram-negative
– The cell wall loses a stain or is decolorized by alcohol
• Aerobic
– Depend on oxygen for survival
• Anaerobic
– Do not use oxygen
Bacteria and Resistance to Antibiotics
• Adapt to their environment
• The longer an antibiotic has been in use, the greater the chance that
the bacteria will develop into a resistant strain
• Combination drugs – clavulanic acid, sulbactam
Aminoglycosides
• A group of powerful antibiotics used to treat serious infections caused
by gram-negative aerobic bacilli
• Common medications:
– Amikacin (Amikin)
– Gentamicin (Garamycin)
– Kanamycin (Kantrex)
– Neomycin (Mycifradin)
– Streptomycin
– Tobramycin (Nebcin, Tobrex)
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– Bactericidal
– Indications: Treatment of serious infections caused by
susceptible bacteria
• Examples include: Pseudomonas aeruginosa, E. coli, Proteus,
Klebsiella-Enterobacter-Serratia, et al.
– Actions: Inhibits protein synthesis in susceptible strains of gramnegative bacteria causing cell death
• Pharmacokinetics
– Poorly absorbed from the GI tract, but rapidly absorbed after IM
injection, reaching peak levels within 1 hour
– Widely distributed throughout the body, crossing the placenta
and entering breast milk
– Excreted unchanged in the urine and have an average half-life of
2 to 3 hours
– Depend on the kidney for excretion and are toxic to the kidney
• Contraindications
– Known allergies, renal or hepatic disease, hearing loss
– Pt’s receiving other ototoxic drugs (need reduced dose)
• Adverse Effects
– Ototoxicity – vertigo, tinnitus, balance problems, hearing loss
– Nephrotoxicity – monitor BUN/creatinine, intake & output
– Neuromuscular blockade – Observe for HA, lethargy, tremor,
paresthesias
• Drug-to-Drug Interactions
– Diuretics, neuromuscular blockers
• Nursing implications:
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– Obtain baseline renal function, monitor I&O, keep pt hydrated,
safety precautions
Carbapenems
• Bactericidal: inhibit bacterial cell membrane synthesis; Very broadspectrum
• Uses: serious intra-abdominal, urinary tract, skin & skin structure,
bone & joint, gynecological infections
• Excreted unchanged in urine – monitor kidney function
• imipenem-cilastatin, doripenem, merropenem, ertapenem
• Contraindications:
• Allergy, seizure disorder, meningitis, lactation
• Caution in pregnancy
• Adverse Effects:
• GI: pseudomembranous colitis, C.diff, N/V
• Superinfections
• Neuro: headache, dizziness, AMS, seizures
• Drug Interactions:
• Valproic acid, imipenem + ganciclovir, merropenem +
probenecid
• What are the nursing implications?
Cephalosporins
• Similar to penicillin in structure and activity
• Action
– Interfere with the cell wall–building ability of bacteria when they
divide
– Bactericidal & bacteriostatic
– Broad spectrum –divided into 4 generations
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• Indications
– Treatment of infections caused by susceptible bacteria
• Pharmacokinetics
– Well absorbed from the GI tract
– Metabolized in the liver, excreted in the urine
– Contraindications
• Allergies to cephalosporins or penicillin
– Reserve use for appropriate situations – resistant strains are
appearing
– Adverse Effects:
• GI upset
• CNS - HA, dizziness, lethargy, paresthesias
• Nephrotoxicity
• Superinfections
• Phlebitis
– Drug Interactions
– Aminoglycosides – renal toxicity
– Oral anticoagulants – increased bleeding
– Alcohol – disulfiram-like reaction – flushing, throbbing HA, N/V,
chest pain, palpitations, dyspnea, syncope, vertigo, blurred
vision
– Nursing Implications:
• Small, frequent meals; keep hydrated
• Warm compresses/massage to injection sites if painful/swollen
• Safety measures if CNS effects occur
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• Avoid ETOH while receiving cephalosporin therapy & for at least
72 hrs after completing the drug course
Cephalosporins: Four Generations
– First Gen:
– Good gram-positive coverage
–
Gram negative – “PEcK”- Proteus mirabilis, E.coli, Klebsiella
pneumoniae
– Used for surgical prophylaxis, URIs, otitis media, skin & GU
infections
– Second Gen:
– Less effective gram-positive
– Better gram-negative coverage - “HENPEcK” – Haemophilus
influenzae, Enterobacter aerogenes, Neisseria species + “PEcK”
– Third Gen:
– Most potent group against gram-negative
– “HENPEcKS” – HENPEcK + Serratia marcescens
– Weak against gram-positive
– Fourth Gen:
– Newest cephalosporin
– Gram positive and negative
– Used to treat cephalosporin resistant staph & Pseudomonas
aeruginosa
Fluoroquinolones
• Relatively new class of antibiotics with a broad spectrum of activity
• Indications: Treating infections caused by susceptible strains of gramnegative bacteria. Includes: urinary track, respiratory track, and skin
infections
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– Ciprofloxacin treats anthrax and typhoid fever
• Actions: Interferes with DNA replication in susceptible gram-negative
bacteria, preventing cell reproduction
• Pharmacokinetics:
– Absorbed in GI tract
– Metabolized in the liver
– Excreted in urine and feces
• Contraindications
– Known allergy, pregnancy, or lactating women
– Children <18 yo – lesions in developing cartilage
• Drug-to-Drug Interactions
– Iron salts, sucralfate, mineral supplements, antacids – effect of
quinolone decreased
– Drugs that prolong QT interval
– Theophylline – increased levels of theophylline
– NSAIDs – CNS stimulation
• Adverse Effects:
– CNS - Headache, dizziness, depression, insomnia
– GI - Nausea, vomiting, diarrhea, dry mouth
– Integumentary - Rash, photosensitivity
– Other: Fever, bone marrow depression
Black box warning: tendinitis & tendon rupture (>60yrs, steroids, transplant)
Penicillin's
• First antibiotic – high resistance
• Bactericidal: inhibit cell wall synthesis
• Indications:
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– Gram positive and negative
– Syphilis
– Meningococcus
– Pneumococcus
– Streptococcus & others
• Contraindications:
– Allergy to PCN or cephalosporins
• Common adverse effects
– GI upset
– Superinfections – yeast infections
– Hypersensitivity
• Drug Interactions
– Tetracyclines – decrease effectiveness of penicillins
– IV Aminoglycosides – inactivation of aminoglycoside
• Nursing Implications:
– Complete full course of treatment
– Take on empty stomach will 8 oz water
– Do not take with fruit juice, soft drinks, milk
– Storage requirements
– Small, frequent meals, hydration
– Treat superinfections
– Warm compress/massage to injection sites
Sulfonamides
• Drugs that inhibit folic acid synthesis that is required in RNA/DNA
– Does not affect human cells—use pre-formed dietary folic acid
• Inexpensive, less used d/t resistance
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• Action
– Interfere with the cell wall–building ability of bacteria when they
divide
• Indications
– Treatment of infections caused by gram-negative and grampositive bacteria
• Pharmacokinetics
– Well absorbed from the GI tract
– Metabolized in the liver, excreted in the urine
• Indications:
• Chlamydia trachomatis – can lead to blindness
• Nocardia – causes pneumonias & brain abscesses
• UTIs, STDs
• Otitis media
• Ulcerative colitis, Crohn’s
• RA
• Pneumocystis carinii
• Contraindications
• Allergy to sulfonylureas or thiazide diuretics
• Pregnancy & lactation - teratogenic
• Adverse Effects
• GI symptoms; Renal effects related to the filtration of the drug
• Drug-to-Drug Interactions
• Cross sensitivity with thiazide diuretics
• Sulfonylureas
• Antidiabetics - hypoglycemia
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• Cyclosporine - nephrotoxicity
Sulfonamides: Adverse Effects
• Blood - Bone marrow depression
• Integumentary - Photosensitivity, rash
• GI - N/V/D/A, abd pain, stomatitis, hepatic injury
• Renal - Crystalluria, hematuria, proteinuria
• CNS - HA, dizziness, vertigo, ataxia, convulsions, depression
Tetracyclines
• Developed as semisynthetic antibiotics based on the structure of a
common soil mold
• Widespread resistance
• Action
– Inhibits protein synthesis in susceptible bacteria, preventing cell
replication (bacteriostatic)
• Toxic to humans in high concentrations - affected protein
similar protein found in human cells
• Indications
– Treatment of various infections caused by susceptible strains of
bacteria; acne when penicillin is contraindicated for eradication
of susceptible organisms
• Pharmacokinetics
– Adequately absorbed from the GI tract
– Concentrated in the liver, excreted unchanged in the urine
Tetracyclines: Indications
• Wide spectrum
– Mycoplasma, Rickettsia
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– protozoa
– Acne
– Chlamydia
– Lyme disease
• Contraindications
– Allergy to tetracyclines or tartrazine
– Pregnancy and lactation
– Ophthalmic – in viral, fungal, or mycobacterial infections
• Adverse Effects
– GI, Skeletal – damage to bones and teeth
• Drug-to-Drug Interactions
– Penicillin G, oral contraceptive therapy, methoxyflurane, digoxin
Tetracyclines: Adverse Effects
• GI
– N/V/D, abd pain, glossitis, dysphagia
– Hepatotoxicity
• Skeletal
– Staining & pitting of teeth & bones weakening the structure
• Dermatological
– Photosensitivity, rash
• Superinfections
• Local effects – pain, stinging w/ topical/ocular
• Hematological
– Bone marrow depression, hemolytic anemia
Tetracyclines: Interactions
• PCN G – decreased effectiveness
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• Oral contraceptives – decreased effectiveness
• Digoxin – toxicity
• Decreased absorption of tetracyclines with:
– Calcium salts, magnesium salts, zinc salts, aluminum salts,
bismuth salts, iron, charcoal & dairy
Mycobateria
• Mycobacteria hold a stain even after destaining agent (acid) applied
– Known as acid-fast bacilli
• Have an outer coat of mycolic acid that protects them from
disinfectants – allows them to survive for long periods in the
environment
• Category includes pathogens causing TB and leprosy
• Need extended course of treatment to eradicate
• Treated with antimycobacterials
Antimycobacterial
• Action
– Act on the DNA of the bacteria leading to lack of growth and
eventual bacterial death
• Indications
– Treatment of acid fast bacteria
• Pharmacokinetics
– Well absorbed from the GI tract
– Metabolized in the liver, excreted in the urine
Antimycobacterials
• Indications:
– Tuberculosis (TB)
• Caused by Mycobacterium tuberculosis
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– Leprosy or Hansen’s disease – Mycobacterium leprae –
disfiguring skin lesions & destroys resp tract
– Mycobacterium avium complex – seen in patients with AIDS and
others who are severely immuno-compromised
• Contraindications
– Allergy, renal or hepatic failure
• Adverse Effects
– CNS effects and GI irritation
• Drug-to-Drug Interactions
– Rifampin and INH can cause liver toxicity
Antimycobacterial Drugs: Adverse Reactions
• CNS
– dizziness, headache, malaise, drowsiness, hallucinations
• GI
– N/V, anorexia, stomach upset, abd pain
• Rifampin/rifabutin/rifapentine
– Orange discoloration of body fluids – sweat, urine, tears – may
stain clothes, contact lenses
• INH + rifampin
– Possibility of toxic liver reactions
• Nursing Implications:
– Monitor liver & renal function
– Therapy may last for up to 24 months
– Take medications exactly as ordered, same time every day
– Pt teaching:
• Adequate nutrition and fluids
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• Patients should not consume alcohol
• Barrier contraceptives
• Alert to possible staining of clothing
Antituberculosis Drugs
• Treatment for 6 months-2 yrs
• Treated with drugs in combo to decrease emergence of resistant
strains
First-Line Drugs
isoniazid
rifapentine
ethambutol
rifampin
pyrazinamide
streptomycin
Leprostatic drugs
• dapsone – inhibits folate synthesis
– Also used to treat:
– pneumocystis carinii pneumonia in AIDS patients
– brown recluse spider bites
– acne
Ketolide
• telithromycin (Ketek)
– Introduced in 2004
– Block protein synthesis leading to cell death
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– Mild to moderate CAP caused by:
• S. pneumoniae, H. influenzae, M. catarrhalis,
Chlamydophila pneumoniae & Mycoplasma pneumoniae
– Available in oral form only
• Adverse reactions:
– GI discomfort, superinfections
• Contraindications:
– Cardiac disease (with prolonged QT) or bradycardia, myasthenia
gravis
• Drug interactions:
– Antiarrhythmics, statins
Lincosamides
• clindamycin (Cleocin)
• lincomycin (Lincocin)
• Treatment of severe infections:
– Septicemia, chronic bone & joint infections
• Affect bacterial protein synthesis
• Adverse effects – GI:
– Fatal pseudomembranous colitis
Macrolides
• erythromycin
• azithromycin (Zithromax)
• clarithromycin (Biaxin)
• dirithromycin (Dynabac)
• Alter protein synthesis within bacterial cells
• Bacteriostatic or bactericidal
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Macrolides: Indications
• Strep infections
• Mild to moderate URI & LRI
• Gonorrhea, Chlamydia, Mycoplasma
• Listeria, Legionella
• Syphilis, Lyme disease
• Adverse Effects:
• GI:
– Abd cramping, anorexia, nausea, vomiting, diarrhea,
pseudomembranous colitis
• Neuro:
– Confusion, abnormal thinking, uncontrollable emotions
• Other:
– Rash, superinfections
• Drug Interactions: Digoxin - toxicity
Monobactam
• Aztreonam (Azactam)
– Gram neg enterobacteria
– Disrupts bacterial wall synthesis
– UTI, skin, intra-abdominal, gynecological infections, septicemia
– Use with caution in pts with allergy to PCN or cephalosporins
– Adverse:
• GI effects – nausea, GI upset, vomiting, diarrhea
• Hepatic enzyme elevation
• Anaphylaxis
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Lipoglycopeptides
• 2010: televancin (Vibativ)
– Semi-synthetic derivative of vancomycin
– Inhibit cell wall synthesis
– Complicated skin & skin structure infections caused by:
• Resistant staph, strep, Enterococcus
– Black box – fetal risk
– Adverse – GI, nephrotoxicity, prolonged QT, red man syndrome
Other Antibiotics
• linezolid (Zyvox)
– Introduced in 2000
– Used to treat vancomycin-resistant Enterococcus faecium (VRE),
hospital-acquired skin & skin structure infections, including
those with MRSA
• quinupristin and dalfopristin (Synercid)
– 30:70 combination, work synergistically
– Used for bacteremia & infections caused by vancomycinresistant Enterococcus (VRE) and other complicated skin
infections, MRSA
– May cause arthralgias, myalgias
• daptomycin (Cubicin)
– 2003 - lipopeptide
– Used to treat complicated skin & soft-tissue infections caused by
MRSA and other gram + bacteria
• vancomycin (Vancocin)
– Bactericidal - destroys cell wall
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– Treatment of choice for MRSA
– Given PO for C-diff of colon
– Monitor blood levels
– May cause ototoxicity & nephrotoxicity
– Monitor IV site closely
– Red man syndrome
• Hypotension, flushing/itching of head, neck, face, upper
trunk
• Antihistamine may be ordered to reduce these effects
– Ensure adequate hydration (2 L fluids/24 hr)
• tygecycline (Tygacil)
– 2005
– Treatment of complicated skin & skin structure infections
– Intra-abdominal infections
– Use with caution in pts with tetracycline allergy
– Women should use a barrier form of contraception
– Adverse: pseudomembranous colitis, rash, superinfections
• Fidaxomicin – 2011
– C. difficile
– Minimal systemic absorption
– Effect is directly in GI tract
– Inhibitis bacterial RNA polymerase causing cell death
– Taken orally twice daily
• Rifaximin (Xifaxan)
– 2004
– Blocks bacterial RNA synthesis
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– Directly effects E.coli
– Used for hepatic encephalopathy
– Taken orally, little systemic absorption
New Classes of Antibiotics and Adjuncts
• Daptomycin
• Linezolid (Zyvox)
• Tigecycline
• Streptogramins
Antibiotic Use Across the Life Span
• Pediatric Population
• Adult Population
• Geriatric Population
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