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Flashcards in Exam 4-1 Deck (72):
1

Antibiotics

Medications used to treat bacterial infections
*Ideally, before beginning antibiotic therapy, the suspected areas of infection should be cultured to identify the causative organism and potential antibiotic susceptibilities

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Bacterial Morphology Shapes

*Coccus
*Bacillus
*Coccobacillus
*Fusiform Bacillus
*Vibrio
*Spirillum
*Spirochete

3

Gram Positive Bacteria

*Actinobacteria
*Firmicutes

4

Firmicutes

*Bacilli, order Bacillales
*Bacilli, order Lactobacillales
*Clostridia
*Mollicutes

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Actinobacteria

*Actinomyces
*Arthrobacter
*Corynebacterium
*Frankia
*Micrococcus
*Micromonospora
*Mycobacterium
*Nocardia
*Propionibacterium
*Streptomyces

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Bacilli, order Bacillales

*Bacillus
*Listeria
*Staphylococcus

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Bacilli, order Lactobacillales

*Enterococcus
*Lactobacillus
*Lactococcus
*Leuconostoc
*Pediococcus
*Streptococcus

8

Clostridia

*Acetobacterium
*Clostridium
*Eubacterium
*Heliobacterium
*Heliospirillum
*Megasphaera
*Pectinatus
*Selenomonas
*Zymophilus
*Sporomusa

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Mollicutes

*Mycoplasma
*Spiroplasma
*Ureaplasma
*Erysipelothrix

10

Gram Negative Bacteria

* Acinetobacter- Acinobacillus
*Bordetella- Brucella
*Campylobacter- Cyanobacteria
*Enterobacter- Erwinia
*Escherichia coli- Franciscella
*Helicobacter- Hemophilus
*Klebsiella- Legionella
*Moraxella- Neisseria
*Pateurella- Proteus
*Pseudomonas- Samonella
*Serratia- Shigella
*Treponema- Vibrio
*Yesinia

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Empiric therapy

Treatment of an infection before specific culture information has been reported or obtained.

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Definitive Therapy

Antibiotic therapy tailored to treat organism identified with cultures

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Prophylactic Therapy

Treatment with antibiotics to prevent an infection, as in intraabdominal surgery or after trauma

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Therapeutic Response

Decrease in specific signs and symptoms of infection are noted (fever, elevated WBC, redness, inflammation, drainage, pain)

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Subtherapeutic Response

Signs and symptoms of infection do not improve

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Antibiotic Therapy Cont.

*Superinfection
*Pseudomembranous colitis
*Host factors
*Genetic host factors
-G6PD
-Slow acetylation
*Allergic reactions

17

Antibiotic: Classes

*Sulfonamides
*penicillins
*cephalosporins
*macrolides
*quinolones
*aminoglycosides
*tetracyclines
*others

18

Antibiotic Therapy: Mechanism of Action

*Interference with cell wall synthesis
*Interference with protein synthesis
*Interference with DNA replication
*Acting as a metabolite to disrupt critical metabolic reactions inside the bacterial cell

19

Actions of Antibiotics

*Bacterial: Kill bacteria
*Bacteriostatic: inhibit growth of susceptible bacteria, rather than killing them immediately; will eventually lead to bacterial death

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Antibiotics: Sulfonamides

One of the first groups of antibiotics
*sulfadiazine
*sulfamethoxazole
*sulfisoxazole

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Sulfonamides are often-

combined with another antibiotic
-sulfamethoxazole combined with trimethoprim (a nonsulfonaminde antibiotic), known as Bactrim, Septra, or co-trimoxazole (SMX-TMP)

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Sulfonamides: Mechanism of Action

*Bacteriostatic Action
*Prevent synthesis of folic acid required for synthesis of puriness and nucleic acid
*Do not affect human cells or certain bacteria- they can use preformed folic acid
*Only affect organisms that synthesize their own folic acid

23

Sulfonamides: Indications

*Effective against both gram-positive and gram-negative bacteria
*Treatment of UTIs caused by susceptible strains of:
-Enterobacter spp., Escherichia coli, Klebsiella spp., Proteus vulgaris, Staphylococucus aureus
*Pneumocystis jiroveci pneumonia (PJP)
-sulfamethoxazole/trimethoprim (co-trimoxazole)
*Upper respiratory tract infections

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Sulfonamides: Adverse Effects-Blood

Hemolytic and aplastic anemia, agranulocytosis, thrombocytopenia

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Sulfonamides: Adverse Effects: Integumentary

Photosensitivity, exfoliative dermatitis, Stevens-Johnson syndrome, epidermal necrlysis

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Sulfonamides: Adverse Effects: GI

*N/V/D, pancreatitis

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Sulfonamides: Adverse Effects: Other

*Convulsions, crystalluria, toxic nephrosis, headache, peripheral neuritis, urticaria

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B-Lactam Antibiotics

*Penicillins
*Cephalosporins
*Carbapenems
*Monobactams

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Penicillins

*Natural penicillins
*Penicillinase-resistant penicillins
*Aminopenicillins
*Extended-spectrum penicillins

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Natural penicillins

-penicllin G, penicillin V

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Penicillinase-resistant drugs

*cloxacillin, dicloxacillin, nafcillin, oxacillin

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Aminopenicillins

-amoxicillin, ampicillin

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Extended-spectrum penicillins

piperacillin, ficarcillin, carbenicillin

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Penicillins was first introduced in

1940's

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Bactericidal inhibits

cell wall synthesis

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Penicillins kill a-

wide variety of bacteria

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Bacteria produce enzymes capable of-

destroying penicillins
-these enzymes are known as beta-lactamases
-As a result, the medication is not effective

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Chemicals have been developed to-

inhibit these enzymes:
-clavulanic acid
-tazobactam
-sulbactam

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These chemicals bind with-

B-lactamase and prevent the enzyme from breaking down the penicillin, thus making the penicillin more effective

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Penicillin B-lactamase inhibitor combination products

*ampicillin+ sulbactam= Unasyn
*amoxicillin+clavulanic acid=Augmentin
*ticarcillin+ clavulanic acid= Timentin
*piperacillin+tazobactam=Zosyn

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Penicillins: Mechanism of Action

*Penicillins enter the bacteria via the cell wall
*Inside the cell they bind to penicillin-binding protein
*Once bound, normal cell wall synthesis is disrupted
*Result: bacteria cells die from cell lysis
*Penicillins do not kill other cells in the body

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Penicillins: Indications

*Prevention and treatment of infections caused by susceptible bacteria, such as:
-Gram-positive bacteria
-Streptococcus spp. Entercoccus spp. Staphylococcus spp.

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Penicillins: Adverse Effecs

*Allergic reactions occur 0.7% to 4%
-Urticaria, pruitus, angioedema
*Those allergic to penicillins have a fourfold to sixfold increased risk of allergy to other B-lactam antibiotics
*Cross-reactivity between penicillins and cephalosporins is between 1% and 4%

44

Penicillin: Common adverse effects

Nausea, vomiting, diarrhea, abdominal pain

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Penicillins: Interactions

Oral contraceptives

46

Cephalosporins

*First generation
*Second generation
*Third generation
*Fourth generation
*Fifth generation (not yet marketed)
*Semisynthetic derivatives from a fungus
*Structurally and pharmacologically related to penicillins
*Bactericidal action
*Broad spectrum
*Divided into groups according to their antimicrobial activity

47

Cephalosporins: First Generation

*Good gram-positive coverage
*Poor gram-negative coverage
*Parenteral and PO forms
*Examples:
-cefadroxil
-cephradine
-cefazolin
-cephalexin
Used for surgical prophylaxis, and for susceptible staphylococcal infections
**cefazolin (Ancef and Kefzol): IV or IM
**cephalexin (Kefzol): PO

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Cephalosporins: Second Generation

Good Gram-positive coverage
Better gram-negative coverage than first generation
Examples:
-cefaclor
-cefprozil
-cefoxitin
-cefuroxime
-loracabef
-cefotetan

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cefoxitin (Mefoxin): IV and IM

-used prophylactically for abdominal or colorectal surgeries
-Also kills anaerobes

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cefuroxime

-surgical prophylaxis
-does not kill anaerobes

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Cephalosporins: Third Generation

*Most potent group against gram-negative bacteria
*Less active against gram-positive bacteria
Examples:
ceftibuten
cefotaxime
ceftazidime
cefdinir
ceftizoxime
ceftriaxone
ceftazidime

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ceftriaxone (Rocephin)

*IV and IM, long half-life, once a day dosing
*Elimination is primarily hepatic
*Easily passes meniges and diffuse into CSF to treat CNS infections

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ceftazidime (Ceptaz)

*IV and IM forms
*Excellent gram-negative coverage
*Used for difficult to treat organisms such as Pseudomonas spp.
*Eliminate renally instead of biliary route

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Cephalosporins: Fourth Generations

*Broader spectrum of antibacterial activity than third generation, especially against gram-positive bacteria
*Uncomplicated and complicated UTI
-cefepime (Maxipime)

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Cephalosporins: Fifth Generation

*Ceftobipriole (not available)
*Broader spectrum of antibacterial activity
*Effective against a wide variety of organisms
-MRSA
-Pseudomonas spp.

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Cephalosporins: Adverse Effects

*Similiar to penicillins
-Mild diarrhea, abdominal cramps, rash, pruritis, redness, edema
*Potential cross-sensitivity with penicillins if allergies exist

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Carbapenems

*Very broad-spectrum antibacterial action
*Reserved for complicated body cavity and connective tissue infections
*May cause drug-induced seizure activity
-this risk can be reduced with proper dosage
*All given parenterally

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Carbapenems: imipenem/cilastatin (Primaxin)

-used for treatment of bone, joint, skin and soft-tissue infections
-Cilastatin inhibits an enzyme that breaks down imipenem
*meropenem (Merrem)
*ertapenem (Invanz)
*doripenem (Doribax)

59

Monobactams

*aztreonam (Azactam)
-Synthetic beta-lactam antibiotic
-Primarily active against aerobic gram-negative bacteria (E. Coli, Klebsiella spp., Pseudomonas spp.)
-Used for moderately severe systemic infections and UTI's

60

Macrolides

*erythromycin (E-mycin, E.E.S)
*azithromycin (Zithromax)
*clarithromycin (Biaxin)
*dirithromycin

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Macrolides: Mechanism of Action

*Prevent protein sythesis within bacterial cells
*Consider bacteriostatic
*Bacteria will eventually die
*In high enough concentrations, may also be bactericidal

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Macrolides: Indications

*Strep infections
-Streptococcus pyogenes
(group A B-hemolytic streptococci)
*Mild to moderate URI and LRI
-Haemophilus influenzae
*Spirochetal infections
-Syphilis and Lyme disease
*gonorrhea, Chlamydia, Mycoplasma

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Macrolides: Indications cont'd

azithromycin and clarithromycin
-recently approved for mycobacterium avium-intracellular complex infection (opportunistic infection associated with HIV/AIDS)
*clarithromycin
-recently approved for use in combination with omeprazole for treatment of active ulcer disease associated with Helicobacter pylori infection

64

Macrolides: Adverse Effects

*GI effects, primarily with erythromycin
-nausea, vomiting, diarrhea, hepatotoxicity, flatulence, jaundice, anorexia
-Newer drugs, azithromycin and clarithromycin: fewer GI adverse effects, longer duration of action, better efficacy, better tissue penetration

65

Ketolide

*telithromycin (Ketek)
-Only drug in this class
-Better antibacterial coverage than mactolides
-Active against gram-positive bacteria, including multi-drug resistant strains of S. pneumoniae
-Associated with severe liver disease
-Use is limited

66

Tetracyclines

*demeclocycline (Declomycin)
*oxytetracycline
*tetracycline
*doxycycline (Doryx, Vibramycin)
*minocycline
*tigecycline (Tygacil)

67

Tetracycline: Characteristics

*Natural and semisynthetic
*Obtained from cultures of Streptomyces
*Bacteriostatic-inhibit bacterial growth
*Inhibit protein synthesis

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Tetracyclines: Info

*Bind (chelate) Ca2+, Mg2+, and Al3+ ions to form insoluble complexes
*Dairy products, antacids and iron salts reduce oral absorption of tetracyclines
*Should not be used in children under age 8 or in pregnant/lactating women because tooth discoloration can occur if the drug binds to the calcium in the teeth

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Tetracyclines: Indications

*Broad spectrum
-Gram negative and gram positive organisms, protozoa, Mycoplasma, Rickettsia, Chlamydia, syphilis, Lyme disease, acne

70

Tetracyclines: Adverse Effects

*Strong affinity for calcium
-Discoloration of permanent teeth and tooth enamel in fetuses and children, or nursing infants if taken by the mother
*May retard fetal skeletal development if taken during pregnancy

71

Tetracycllines: Adverse Effects/Alteration in intestinal flora may result in:

*Superinfection (overgrowth of nonsusceptible organisms such as Candida)
*Diarrhea
*Pseudomembranous colitis

72

Tetracylines: Adverse Effects/May also cause:

*Vaginal candidiasis
*Gastric upset
*Enterocolitis
*Maculopapular rash