Exam 4-1 Flashcards
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
Bacterial Morphology Shapes
- Coccus
- Bacillus
- Coccobacillus
- Fusiform Bacillus
- Vibrio
- Spirillum
- Spirochete
Gram Positive Bacteria
- Actinobacteria
* Firmicutes
Firmicutes
- Bacilli, order Bacillales
- Bacilli, order Lactobacillales
- Clostridia
- Mollicutes
Actinobacteria
- Actinomyces
- Arthrobacter
- Corynebacterium
- Frankia
- Micrococcus
- Micromonospora
- Mycobacterium
- Nocardia
- Propionibacterium
- Streptomyces
Bacilli, order Bacillales
- Bacillus
- Listeria
- Staphylococcus
Bacilli, order Lactobacillales
- Enterococcus
- Lactobacillus
- Lactococcus
- Leuconostoc
- Pediococcus
- Streptococcus
Clostridia
- Acetobacterium
- Clostridium
- Eubacterium
- Heliobacterium
- Heliospirillum
- Megasphaera
- Pectinatus
- Selenomonas
- Zymophilus
- Sporomusa
Mollicutes
- Mycoplasma
- Spiroplasma
- Ureaplasma
- Erysipelothrix
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
Empiric therapy
Treatment of an infection before specific culture information has been reported or obtained.
Definitive Therapy
Antibiotic therapy tailored to treat organism identified with cultures
Prophylactic Therapy
Treatment with antibiotics to prevent an infection, as in intraabdominal surgery or after trauma
Therapeutic Response
Decrease in specific signs and symptoms of infection are noted (fever, elevated WBC, redness, inflammation, drainage, pain)
Subtherapeutic Response
Signs and symptoms of infection do not improve
Antibiotic Therapy Cont.
- Superinfection
- Pseudomembranous colitis
- Host factors
- Genetic host factors
- G6PD
- Slow acetylation
- Allergic reactions
Antibiotic: Classes
- Sulfonamides
- penicillins
- cephalosporins
- macrolides
- quinolones
- aminoglycosides
- tetracyclines
- others
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
Actions of Antibiotics
- Bacterial: Kill bacteria
- Bacteriostatic: inhibit growth of susceptible bacteria, rather than killing them immediately; will eventually lead to bacterial death
Antibiotics: Sulfonamides
One of the first groups of antibiotics
- sulfadiazine
- sulfamethoxazole
- sulfisoxazole
Sulfonamides are often-
combined with another antibiotic
-sulfamethoxazole combined with trimethoprim (a nonsulfonaminde antibiotic), known as Bactrim, Septra, or co-trimoxazole (SMX-TMP)
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
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
Sulfonamides: Adverse Effects-Blood
Hemolytic and aplastic anemia, agranulocytosis, thrombocytopenia
Sulfonamides: Adverse Effects: Integumentary
Photosensitivity, exfoliative dermatitis, Stevens-Johnson syndrome, epidermal necrlysis
Sulfonamides: Adverse Effects: GI
*N/V/D, pancreatitis
Sulfonamides: Adverse Effects: Other
*Convulsions, crystalluria, toxic nephrosis, headache, peripheral neuritis, urticaria
B-Lactam Antibiotics
- Penicillins
- Cephalosporins
- Carbapenems
- Monobactams
Penicillins
- Natural penicillins
- Penicillinase-resistant penicillins
- Aminopenicillins
- Extended-spectrum penicillins
Natural penicillins
-penicllin G, penicillin V
Penicillinase-resistant drugs
*cloxacillin, dicloxacillin, nafcillin, oxacillin
Aminopenicillins
-amoxicillin, ampicillin
Extended-spectrum penicillins
piperacillin, ficarcillin, carbenicillin
Penicillins was first introduced in
1940’s
Bactericidal inhibits
cell wall synthesis
Penicillins kill a-
wide variety of bacteria
Bacteria produce enzymes capable of-
destroying penicillins
- these enzymes are known as beta-lactamases
- As a result, the medication is not effective
Chemicals have been developed to-
inhibit these enzymes:
- clavulanic acid
- tazobactam
- sulbactam
These chemicals bind with-
B-lactamase and prevent the enzyme from breaking down the penicillin, thus making the penicillin more effective
Penicillin B-lactamase inhibitor combination products
- ampicillin+ sulbactam= Unasyn
- amoxicillin+clavulanic acid=Augmentin
- ticarcillin+ clavulanic acid= Timentin
- piperacillin+tazobactam=Zosyn
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
Penicillins: Indications
- Prevention and treatment of infections caused by susceptible bacteria, such as:
- Gram-positive bacteria
- Streptococcus spp. Entercoccus spp. Staphylococcus spp.
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%
Penicillin: Common adverse effects
Nausea, vomiting, diarrhea, abdominal pain
Penicillins: Interactions
Oral contraceptives
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
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
Cephalosporins: Second Generation
Good Gram-positive coverage Better gram-negative coverage than first generation Examples: -cefaclor -cefprozil -cefoxitin -cefuroxime -loracabef -cefotetan
cefoxitin (Mefoxin): IV and IM
- used prophylactically for abdominal or colorectal surgeries
- Also kills anaerobes
cefuroxime
- surgical prophylaxis
- does not kill anaerobes
Cephalosporins: Third Generation
*Most potent group against gram-negative bacteria
*Less active against gram-positive bacteria
Examples:
ceftibuten
cefotaxime
ceftazidime
cefdinir
ceftizoxime
ceftriaxone
ceftazidime
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
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
Cephalosporins: Fourth Generations
- Broader spectrum of antibacterial activity than third generation, especially against gram-positive bacteria
- Uncomplicated and complicated UTI
- cefepime (Maxipime)
Cephalosporins: Fifth Generation
- Ceftobipriole (not available)
- Broader spectrum of antibacterial activity
- Effective against a wide variety of organisms
- MRSA
- Pseudomonas spp.
Cephalosporins: Adverse Effects
- Similiar to penicillins
- Mild diarrhea, abdominal cramps, rash, pruritis, redness, edema
- Potential cross-sensitivity with penicillins if allergies exist
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
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)
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
Macrolides
- erythromycin (E-mycin, E.E.S)
- azithromycin (Zithromax)
- clarithromycin (Biaxin)
- dirithromycin
Macrolides: Mechanism of Action
- Prevent protein sythesis within bacterial cells
- Consider bacteriostatic
- Bacteria will eventually die
- In high enough concentrations, may also be bactericidal
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
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
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
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
Tetracyclines
- demeclocycline (Declomycin)
- oxytetracycline
- tetracycline
- doxycycline (Doryx, Vibramycin)
- minocycline
- tigecycline (Tygacil)
Tetracycline: Characteristics
- Natural and semisynthetic
- Obtained from cultures of Streptomyces
- Bacteriostatic-inhibit bacterial growth
- Inhibit protein synthesis
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
Tetracyclines: Indications
- Broad spectrum
- Gram negative and gram positive organisms, protozoa, Mycoplasma, Rickettsia, Chlamydia, syphilis, Lyme disease, acne
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
Tetracycllines: Adverse Effects/Alteration in intestinal flora may result in:
- Superinfection (overgrowth of nonsusceptible organisms such as Candida)
- Diarrhea
- Pseudomembranous colitis
Tetracylines: Adverse Effects/May also cause:
- Vaginal candidiasis
- Gastric upset
- Enterocolitis
- Maculopapular rash
