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Drugs Used to Treat Infections. Chapter 5. Antimicrobials. Drugs used to prevent or treat infection caused by pathogens. Two Classifications. Bactericidal drugs kill bacteria directly Bacteriostatic drugs prevent bacteria from dividing . Infectious Disease.

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  • Drugs used to prevent or treat infection caused by pathogens
two classifications
Two Classifications
  • Bactericidal drugs kill bacteria directly
  • Bacteriostatic drugs prevent bacteria from dividing
infectious disease
Infectious Disease
  • Infections disease involves the presence of pathogen plus clinical signs and symptoms indicating infection.
  • Microorganisms spread by direct contact with infected person or contaminated hands, food, water, or objects.
common bacterial pathogens
Common Bacterial Pathogens
  • Gram positive
    • Staphylococcus aureus
    • Streptocci
    • Enterococci
  • Gram negative
    • Escherichia coli or E-coli
    • Klebsiella
    • Proteus
    • Pseudomonas
  • Part of the normal microbial flora of throat and nasopharynx
  • Common cause of pneumonia, otitis media (ear infection), sinusitis, and meningitis
  • Pneumococcal vaccination available for children / adults
  • Often follows a viral illness that injures the ciliated epithelium of respiratory tract
opportunistic infections
Opportunistic Infections
  • Severe burns
  • Cancer
  • HIV
  • Indwelling IV catheter or urinary catheter
  • Corticosteroid therapy
  • Fungal or viral infections
laboratory tests
Laboratory Tests
  • Gram stain – microscopic identification of organism
  • Culture – identifies causative agent and susceptibility to specific antibiotics
  • Serology – titers or antibodies measured
  • CBC – looking at WBC
  • Throat
  • Wound
  • Urine
  • Sputum
  • Blood
clinical pearl
Clinical Pearl
  • Always collect culture: urine, sputum, wound drainage, or blood prior to starting antibiotic therapy.
  • If technician is drawing blood make sure it has been done before starting antibiotics.
two types of bacteria
Two Types of Bacteria
  • Aerobic – grow and live in presence of oxygen
    • Staph & Strep
  • Anaerobic – cannot grow in presence of oxygen
    • Deep wounds
    • Characterized by abscess formation, foul-smelling pus and tissue destruction
community acquired infection
Community-Acquired Infection
  • Less severe and easier to treat, although drug resistant strains are increasing
  • Remember Staph is everywhere – it is normal flora on skin and in the upper respiratory tract
  • MRSA: methicillin-resistant-Staphylococcus aureus
nosocomial infections
Nosocomial Infections
  • More severe and difficult to manage because they often result from drug-resistant microorganisms and occur in clients whose resistance is impaired
    • Pseudomonas
    • Proteus
bacterial resistance
Bacterial Resistance
  • Bacteria develop the ability to produce substances which block the action of antibiotics or change their target or ability to penetrate the cells.
what causes resistance
What causes resistance?
  • Widespread use of antimicrobial drug
  • Interrupted or inadequate antimicrobial treatment of infection
  • Type of bacteria – gram-negative strains have higher rates of resistance
  • Re-occurring infections
  • Condition of the host
  • Location – critical care areas
host defense mechanisms
Host Defense Mechanisms
  • Skin
  • Mucous membranes
  • Secretions in GI, GU and respiratory tract
  • Coughing, swallowing, peristalsis
  • WBC – phagocytes – battling white cells
    • Elevated in the presence of infection
break down of natural barriers
Break-down of Natural Barriers
  • Breaks in skin, open lesions, prosthetic devices (total hip or knee)
  • Urinary catheters
  • Intravenous catheters
  • Impaired blood supply
  • Malnutrition
  • Poor personal and oral hygiene
  • Neonate / Geriatric
client history assessment
Client History / Assessment
  • Allergies
  • Previous drug reactions
  • Baseline renal and liver function
  • Review culture reports for appropriate antibacterial drug choice
  • Patient response to antibiotics therapy
    • Are they getting better?
    • Any side effects?
drug selection
Drug Selection
  • Empiric therapy – antibiotics may need to be started before the organism is identified
  • Cultures take 48 to 72 hours
  • A single broad spectrum may be used to cover suspected organism
switching antibiotics
Switching Antibiotics
  • If cultures indicate a specific antibiotic
  • If the infection is not getting better
  • Designer drugs are more expensive
  • Generic brands may work just as well
  • First generation IM or IV
  • Newer penicillins have been developed that increase gastric acid stability of penicillin
  • Good drug since it enters most bodily fluids: joint, pleural, and pericardial.
  • Not effective against intraocular (eye) or cerebral spinal fluid infection (CNS)
  • Bactericidal action against sensitive bacteria
  • Action: binds to bacterial wall, resulting in cell death
nursing implications
Nursing Implications
  • Vital signs
  • Review lab values especially culture results
  • Ask about previous drug reactions or allergies
  • Observe for allergic reaction
    • IM or IV may occur within 20 to 30 minutes after administration
    • PO may occur in a few days
client teaching
Client Teaching
  • Take around the clock as ordered
  • Observe for super-infections: vaginal discharge, diarrhea, rash or allergic reaction
  • Call MD is fever persists after 24 to 36 hours.
ampicillin synthetic penicillin
Ampicillin – Synthetic Penicillin
  • Broad spectrum effective against several gram-positive and gram-negative bacteria
  • E-coli, proteus, Salmonella, Shigella
  • Not effective against staphylococci on gonococci
  • Bronchitis, sinusitis, and otitis media
  • Bactericidal action – spectrum is broader than penicillin
  • Binds to bacterial wall resulting in cell death
nursing implications1
Nursing Implications
  • Same as penicillin
  • Ask client about oral contraceptive use – drug may cause transient decrease in effectiveness
  • Advise to use additional BC – barrier protection during antibiotic therapy
  • Oral equivalent of Ampicillin
  • Readily absorbed and reaches therapeutic levels rapidly
  • Drug of choice in prevention of bacterial endocarditis
    • Clients with total knee or hip replacement, heart valve replacement need to take prior to any dental work, endoscopy exams
  • Action: binds to bacterial cell wall causing cell death.
  • Therapeutic effects: bactericidal action
  • Spectrum is broader than penicillin
  • Well absorbed from duodenum
  • More resistant to acid inactivation than other penicillins
nursing implication client teaching
Nursing implication / client teaching
  • Same as penicillin
  • Instruct female clients taking oral contraceptives to use an alternate or additional non-hormonal method of contraception during antibiotic therapy
dosing for amoxicillin
Dosing for Amoxicillin
  • Adults: 250 to 500 mg q8h
  • Infants and children less than 20 kg:
    • 20 – 40 mg / kg / day divided into doses q 8 hours
  • Widely used drug derived from fungus
  • Used against gram–negative bacteria
  • Widely absorbed and distributed in most bodily fluids – placenta and breast milk
  • First generation Cephalosporin drugs do not reach therapeutic levels in CNS but 2nd, and 3rd generation drugs do – especially important in treating meningitis
first generation cephalosporins
First Generation Cephalosporins
  • Not used very much since better drugs have been developed
  • Bactericidal action – binds to bacterial cell wall, causing cell death
    • Keflex (PO) still used extensively in treatment of skin infections
    • Ancef – often ordered preoperatively
  • First generation cephalosporin
  • Action: binds to bacterial cell wall membrane, causing cell death
  • Therapeutic effect: bactericidal action against susceptible bacteria
  • Active against many gram-positive cocci – step and staph
client teaching1
Client teaching
  • May be taken with or without food but food may minimize the GI irritation
  • Distribution: may cross placenta or enter breast milk in low concentrations.
  • Excreted entirely by the kidneys.
keflex dosing
Keflex Dosing
  • Adults: 250 – 500 mg q 6 hours
  • Children: 25 – 50 mg / kg / day in divided doses q 6 h
cefazolin or ancef
Cefazolin or Ancef
  • Cefazolin – first generation cephalosporin
  • Well absorbed following IM or IV administration
  • Crosses to placenta and breast milk in small concentrations
  • Minimal CSF penetration
  • Excreted by kidneys
ancef dosing
Ancef Dosing
  • IV
  • Used for UTI, bone and skin infections, endocarditis
  • Not suitable for treatment of meningitis
  • Perioperative prophylaxis – 1 gram within 60 minutes of incision and than every 8 hours for 24 hours
second generation cephalosporins
Second-Generation Cephalosporins
  • More active against some gram-negative organisms and anaerobic organisms than the first generation drugs.
  • May be effective in infections resistant to other antibiotics
  • Penetration into CSF is poor but adequate to be used in meningitis
  • Action: bactericidal – binds to cell wall
  • PO Cephalosporin:
  • Adult: 250 – 500 mg q 8 h
  • Children: 20 - 40 mg/kg/d in 3 divided doses
practice problem
Practice Problem
  • 22 pound child
  • Minimal dose of 20 mg per kg
  • Given q 8 hours
  • 22 pounds to kilogram = 10 kg
  • 20 mg x 10 kg = 200 mg po q day
  • 200 divided by 3 = 66 mg / dose
  • UTI (urinary tract infection), otitis media (ear infection), pharyngitis (throat infection) or URI (upper respiratory infection)
  • Meningitis
  • PO
    • Adults – 250 to 500 mg every 12 hours
    • Children – 15 mg / kg / q 12 hours
  • IM or IV
    • Adults – 1.5 grams every 12 hours
    • Children –
      • 16.7 – 33.3 mg / kg / q 8 hours
      • 15 – 50 mg / kg / q 12 hours
second generation cephalosporin
Second – Generation Cephalosporin
  • Cefuroxime: penetrates cerebrospinal fluid in presence of inflamed meninges
    • Bacterial meningitis: 200 to 240 mg / kg / d in divided doses reduced to 100 mg / kg / dose
    • Moderate infections:
      • > 3 months 50 to 100 mg / kg / d in 3 divided doses
third generation cephalosporins
Third – Generation Cephalosporins
  • Extended protection against gram-negative organisms
  • Used against some resistant organisms to the first and second generation Cephalosporins
  • Increased activity against – Enterobacter, Haemophilus influenza, E. Coli
  • Third – Generation: Claforan – serious infections resistant organisms – E. Coli, Proteus, Klebsiella
  • Fourth – Generation: only used if organism resistant
  • Bactericidal action – inhibits protein synthesis at level of 302 ribosome
  • Treatment of serious gram-negative bacilli and infections caused by staphylococci when penicillin or less toxic drugs are contraindicated
  • Used in hospital acquired infections
  • AIDS
  • Low host resistant client
  • Severe infection
gentamicin or garamycin
Gentamicin or Garamycin
  • Toxic Side Effects:
    • Ototoxicity – hearing – (tinnitus or ringing in ears)
    • Nephrotoxicity – kidney
    • If used in infants / children need to do baseline hearing test (BAER) after treatment
toxicity and overdose
Toxicity and Overdose
  • Gentamicin and tobramycin - Blood levels should be monitored periodically during therapy
  • Draw peak level 30 minutes after IV administration of drug
  • Draw trough level just before the next dose
    • Peak level not to exceed 10 mcg/mL
    • Trough level not to exceed 2 mcg/mL
gentamicin iv
Gentamicin IV
  • Adult dosing
    • 1.5 to 2.5 mg/kg q 12 hours
    • 1 to 1.7 mg/kg q 8 hours
gentamicin iv1
Gentamicin IV
  • Children
    • 6 – 7.5 mg / kg /day in 3 divided doses q8hours
  • Infants
    • 7.5 mg / kg / day in 3 divided doses q 8 hours
  • Premature infants
    • 5 mg / kg in 2 divided doses q 12 hours
clinical pearl1
Clinical Pearl
  • Dosage of Aminoglycosides must be carefully regulated because therapeutic doses are close to toxic doses.
  • Initial dosing based on client weight and desired peak serum concentrations
  • Maintenance dose based on serum drug concentration
  • Synthetic bactericidal drugs with activity against gram negative and gram positive organisms
  • Action: inhibit bacterial DNA synthesis
  • Therapeutic effect: death of susceptible bacteria.
  • Use with caution in OB and pediatrics
  • Well absorbed orally
  • Used in treatment of gonorrhea but not in resistant strains
  • Anthrax
nursing implications client teaching
Nursing implications / client teaching
  • Administer on empty stomach – food may slow or slightly decrease absorption
  • Encourage po fluid intake – to decrease crystalluria
  • Sunscreen
  • If being used to treat gonorrhea – partner needs to be treated
  • 250 to 750 mg q 12 hours po
  • 500 to 1 gram q 8 – 12 h po for pyelonephritis
tetracycline and sulfonamides
Tetracycline and Sulfonamides
  • Some of the older, broad-spectrum bacteriostatic drugs
  • Not used as much do to the development of newer less toxic drugs
  • Used in selected infections
  • Action: bacteriostatic action – inhibits bacterial protein synthesis at the level of the 30S ribosome
  • Treatment of various infections cause by unusual organisms
    • Mycoplasma
    • Chlamydia
    • Richettsia
    • Gonorrhea and syphilis in penicillin allergic clients
side effects
Side Effects
  • Photosensitivity
  • Special Teaching
    • Avoid milk or dairy products, antacids, calcium or magnesium medications
    • Caution to use sunscreen and protective clothing to prevent photosensitivity reaction
    • Contraindicated in children less than 8 years due to permanent staining of the teeth
combination drugs
Combination Drugs
  • Trimethoprim-sulfamethoxazole or Bactrim
  • Two drugs have additive antibacterial effects because they interfere with different strep in bacteria synthesis
  • Action: bactericidal – inhibits metabolism of folic acid in bacteria at two different points
  • Side effects: toxic epidermal necrolysis – Stevens Johnson Syndrome
stevens johnson syndrome
Stevens-Johnson Syndrome
  • First described in 1922 – an immune complex hypersensitivity
  • Drug-induced: penicillins and sulfa
  • Viral infection
  • 3 to 15% morbidity
sign and symptoms
Sign and Symptoms
  • Lesion can erupt from 2-3 weeks after ingestion of a drug
  • Starts with mouth lesions or skin lesions
  • Can have ocular involvement
  • Mange oral lesions with mouthwashes
  • Topical anesthetics to reduce pain
  • Warm compresses to skin lesions
  • Systemic corticosteroids
  • Antimicrobials if cutaneous infections
  • Healing takes 1 – 2 weeks
  • Classification: anti-rheumatics and gastrointestinal anti-inflammatories
  • Action: inhibition of prostaglandin synthesis (inflammation)
  • Used to manage ulcerative colitis / rheumatoid arthritis
    • Azulfidine
    • 3 to 4 g per day q 12 h
    • Used long-term to reduce symptoms
  • Special Instructions: drink with full glass of water
  • May cause orange-yellow discoloration of urine or stain contact lens yellow
  • Used less often due to microbial resistance
  • Therapeutic classification: Anti-infective
  • Pharmacologic classification: Macrolides
  • Action: Suppresses protein synthesis at the level of the 50S bacterial ribosome.
  • Side effects: QT prolongation, ventricular arrhythmias.
  • Trade names: Zithromax, Z-Max
  • Therapeutic classification: anti-infective
  • Pharmacologic classification: macrolide
  • Action: inhibits protein synthesis at the level of the 50S bacterial ribosome
  • Absorption: rapidly absorbed, widely distributed to body tissue. Low CSF levels.
  • Side effects: pseudo membrane colitis (abdominal cramping / diarrhea).
  • Uses: Otitis media, acute exacerbation of chronic bronchitis, pelvic inflammatory disease, chlamydia infections.
  • Special instructions: 1 hour before or 2 hours after eating.
  • Notify health care professional if fever and diarrhea develop, especially is stool contains blood, pus or mucous.
  • Pediatrics: well tolerated – may develop mild diarrhea or rash.
azithromycin dosing
Azithromycin dosing
  • Adult: 500 mg 1st day then 250 mg/day for 4 more days.
  • Children > 6 mo: 10 mg/kg (not to exceed >500 mg / dose.
clindamycin or cleocin
Clindamycin or Cleocin
  • Used in combination with other IV drugs for intra abdominal infections
  • Does not cross the blood-brain barrier – not used in meningitis
  • Action: bactericidal or bacteriostatic depending
  • Inhibits protein synthesis is susceptible bacteria at the level of the 50S ribosome
side effects1
Side Effects
  • Monitor bowel elimination – diarrhea, abdominal cramping, fever or bloody stools – may be signs of pseudo-membranous colitis
  • Treatment of anaerobic infections
  • Action: Bactericidal, trichomonacidal and amebicidal – disrupts DNA and protein synthesis is susceptible organisms
    • Intra-abdominal infections
    • Gynecologic infections
  • PO
  • Gel – acne rosacea
  • Vaginal Suppository – bacterial vagninosis
  • IV – pseudomembranous colitis – intra-abdominal surgery
  • If used for trichomoniasis and client is sexually active the partner needs to be treated.
  • Ovoid alcohol consumption – may cause vomiting and GI upset
  • Dry mouth – may use mouthwash, gum or hard candies to minimize dry mouth
  • Treatment of potentially life-threatening infections when less toxic anti-infective drugs are contraindicated
  • Action: Bactericidal – binds to cell membrane, resulting in cell death
  • Active only against gram-positive microorganisms
  • Used extensively in methicillin-resistant-Staphylococcus aureus (MRSA)
special instructions
Special Instructions
  • Administer IV slowly over 1 hour
  • Watch for hypotension, flushing, and rash
  • “red man syndrome”
  • If symptoms appear may need to slow IV administration or further dilute the medication
nursing assessment
Nursing Assessment
  • Monitor IV site closely – Vancomycin is irritating to tissues and causes necrosis and severe pain (phlebitis).
  • Toxicity – peak serum levels should not exceed 25 mcg / ml and trough level should not exceed 5 – 10 mcg
  • Side effect: Nephrotoxicity and phlebitis
  • Treatment and prophylaxis of recurrent genital herpes, herpes zoster infections (shingles), and chickenpox (Varicella) and herpes encephalitis.
  • Action: inhibition of viral replication, decrease viral shedding and reduced time for healing of lesions.
  • Therapeutic effect: inhibition of viral replication, decreased viral shedding and reduced time for healing of lesions.
  • Widely distributed in CSF
  • Crosses placenta and enters breast milk
  • PO: genital herpes infection, shingles, varicella
  • IV: herpes simplex infections, severe shingles, herpes simplex encephalitis
nursing implications2
Nursing implications
  • Asses for any lesions
  • Monitor neurologic status in herpes encephalitis
  • Monitor BUN and serum Creatinine – kidney function
  • Advise client to take full course of therapy even if lesion are gone
  • Use of condoms in genital herpes
  • No sexual activity with active lesions