Module 16 Antibiotics Flashcards
Bacteria
- Single cell organisms
- Rod, sphere, spiral shaped
- Majority harmless to immune system
- Some beneficial types
Virulence Factors
- Fimbriae & pilli
- Flagella
- Secretion of toxins/enzymes
- Invasion
Fimbriae & Pilli
- Hair like structures
- Project from surface of bacterial cells
- Allow bacteria attachment within body
Flagella
- Aqueous environment
- Swim through body (flagellum)
- Find site to survive
Toxins & Enzymes
- Cause nausea/vomit, diarrhea, cramps
- Mediate toxic reactions with body entry
- Enzymes effect tissue, antibodies
- Degrade defense against infection
Gram Straining
- Used to classify as positive/negative
- Cell wall structure of bacteria
- Amount of peptidoglycan
- Determine antibiotic choice
Gram Positive Cells
- Thick peptidoglycan wall
- Purple stains
- No LPS or outer membrane
- No porins
Gram Negative Cells
- Thin peptidoglycan layer
- Pink stains
- No techoic acid
- LPS on outer membrane
- Outer membrane protects againts bile salt/detergents
- Porins on outer membrane (sugars/ions into bacteria)
Signs of Infection
- Fever
- Malaise
- Local redness
- Swelling
- Increased respiratory rate
- Tachycardia
Selective Toxicity
- Treatment of bacterial infection
- Therapy to destroy bacteria without harming human cells
- Differences between cellular chemistry of humans/bacteria
Mechanisms of Selective Toxicity
- Disrupting bacterial cell wall
- Targeting bacteria unique enzymes
- Disrupting bacterial protein synthesis
Antibiotic Selection
- Identification of bacteria
- Bacterial sensitivity to antibiotic
- Antibiotic access to infection site
- Ability of patient to battle infection
Bacteria Identification
- Prior to treatment selection
- Gram stain rapid test (structural features)
- Culturing
Bacteriostatic Antibiotics
- Stops growth & replication of bacteria
- Stops infection spread
- Immune system attack & remove cells
Bactericidal Antibiotics
- Kill bacteria directly
Determining Bacterial Sensitivity
- Culture bacteria
- Determine minimum inhibitory concentration (MIC)
- Determine minimum bactericidal concentration (MBC) of drug
Difficult Penetration to Site of Action
- Meningitis
- UTI
- Osteomyelitis
- Abscesses
- Otitis media
Meningitis
- Infection of meninges
- Membranes cover brain/spinal cord
- Viral more common than bacterial
- Antibiotic must penetrate meninges
UTI
- Bacteria enters urinary system
- Bladder most common (catheterization)
- Antibiotic must enter urinary system
Osteomyelitis
- Infection of bone
- Limited treatment options, antibiotic must enter bone
- 4-6 week antibiotic period
Abscesses
- Pus/infected material collect under skin
- Difficult to treat, low blood perfusion
Otitis Media
- Infection of middle ear
- Common in children
- Antibiotics do not penetrate inner ear
Ability to Battle Infection
- Immunological state of patient determines antibiotic choice
- Bactericidal used with compromised immune function
- Bacteriostatic compromised immune function may not respond
Impaired Response to Bacteriostatic Antibiotics
- AIDS
- Organ transplant
- Cancer chemotherapy
- Elderly
Complications of Antibiotic Therapy
- Resistance
- Allergy
- Serum sickness
- Superinfection
- Destruction of normal bacterial flora
- Bone marrow toxicity
Resistance
- Bacteria doesn’t respond to antibiotic
- Sensitivity loss
Acquiring Antibiotic Resistance
- Reduction of drug at site of target
- Increased drug inactivation
- Alteration of bacterial target
Drug Reduction at Target Site
- Bacteria decreases antibiotic uptake
- Bacteria increase expression of efflux pumps (extrude antibiotics)
Increased Drug Inactivation
- Bacteria evolution to produce enzymes to inactivate antibiotics
Alteration of Bacterial Target
- Bacteria evolves to contain mutations
- Within antibiotic target
- Making antibiotic ineffective
Resistance Prevention
- Infection prevention
- Diagnosis & effective infection treatment
- Use antibiotics wisely
- Prevent transmission
Allergy Signs
- Urticaria (hives)
- Anxiety
- Swelling (hands, feet, throat)
- Difficulty breathing
- Hypotension
Antibiotic Allergy
- Penicillin most common
- Within 20 mins of dosing
- Stop treatment immediately
- Monitor vitals
- Treatment with epipen & antihistamine
Serum Sickness
- Develops 7-21 days after antibiotic exposure
- Immune system improperly identifies drug as harmful
- Producing immune reaction
Immune Reaction Symptoms
- Fever
- Hives
- Rash
- Joint pain
- Itching
- Angioedema
- Enlarged lymph nodes
Serum Sickness Treatment
- Antihistamine (itching)
- Analgesics (pain)
- Corticosteroids (inflammation)
Superinfection
- New infection develops during antibiotic therapy
- Antibiotics kill pathogenic & normal bacterial flora
- Destruction of bacterial flora allows new bacteria
- Caused by drug-resistant bacteria
- Difficult to treat
Destruction of Normal Bacteria Flora
- Decreased vit K levels (warfarin)
- Increase blood drug levels, toxicity
- Decrease enterohepatic recycling
Bone Marrow Toxicity
- Rare complication, serious
- Aplastic anemia
- Thrombocytopenia
- Agranulocytosis
- Leukopenia
- Watch for bruising/fatigue/sore throat
Penicillin
- Bactericidal
- Effective against active growing/dividing bacteria
- No outer membrane
Penicillin Mechanism of Action
- Inhibit transpeptidases
- Activate autolysins
- Disrupt synthesis of cell wall/promote destruction
- Bacteria take up excess H2O & die
Bacterial Cell Wall
- Composed of peptidoglycan layer
- Transpeptidases & autolysins form Penicillin binding proteins
- Transpeptidases form crossbridge with peptidoglycan
- Autolysins degrade peptidoglycan wall
- Primary target of antibiotics
Penicillin Resistance
- Inability to reach target
- Inactivation
- Mutation to PBPs (low affinity)
Mechanisms of Penicillin Resistance
- Inactivation by beta lactamases enzyme
- Target beta lactam ring of penicillin
- Beta lactase inhibitors block enzyme
Penicillin Classes
- Narrow spectrum penicillins
- Narrow spectrum penicillins resistant penicillins
- Broad spectrum penicillins
- Extended spectrum penicillins
Narrow Spectrum
- Treatment of gram positive bacteria
- Destroyed by gastric acid
- Intravenous/intramuscular administration
- Pneumonia/meningitis treatment
- Considered safe
Narrow Spectrum Penicillins Resistant Penicillins
- Altered side chain
- Not effected by beta lactamase enzymes
- Penicillinase treatment (produce staphylococci)
- Less effective compared to non-penicillinase
- MRSA resistant to this class
Broad Spectrum
- Effective against gram positive & negative bacteria
- Pseudomonas aeruginosa treatment
- Degradation by beta lactase enzymes
Cephalosporins
- Same mechanism of action as penicillin
- Inhibit transpeptidases
- Activate autolysins
- Increase in activity against gram negative bacteria
- Increase resistance to beta lactamases
- Increase ability to penetrate cerebrospinal fluid
- Alternative for penicillin allergies
Vancomycin
- Potentially toxic
- Treatment for serious infections caused by MRSA
- Osteomyelitis, meningitis, pneumonia
- Cause ototoxicity & rapid infusion (red skin)
Vancomycin Mechanism of Action
- Inhibits cell wall synthesis
- Binds to precursors of cell wall synthesis
- Block transglycosylation in cross bridge formation
Tetracyclines
- Protein synthesis inhibitors
- Act on ribosomes
- Prevent addition of amino acids to peptide chain
- Bacteriostatic
- Typhus fever, chlamydia, cholera
Adverse Effects of Tetracyclines
- GI irritation
- Photosensitivity (UV)
- Susceptible to superinfection
Macrolid Antibiotics
- Protein synthesis inhibitors
- Block ribosomes
Block addition of amino acids to peptide chain
- Block ribosomes
Adverse Effects of Macrolide Antibiotics
- GI upset
- QT interval prolongation
Oxazolidinones
- Bacteriostatic (narrow spectrum)
- Protein synthesis inhibitors
- Bind to ribosomes
- Gram positive bacteria
- MRSA & VRE treatment
Adverse Effects of Oxazolidinones
- Reversible myelosuppression
Aminoglycosides
- Bactericidal (narrow spectrum)
- Protein synthesis inhibitors
- Effective versus gram negative bacteria
- Bind to ribosomes
- Rapid & lethal
Adverse Effects of Aminoglycosides
- Ototoxicity
- Reversible nephrotoxicity
Sulfonamides & Trimethoprim
- Block folic acid synthesis
- Bacteria dependant on synthesis of folic acid into DNA
- Administered together to create bactericidal action
- UTI treatment
Adverse Effects of Sulfonamides & Trimethoprim
- Hypersensitivity
- Fever
- Photosensitivity (UV)
- Stevens-johnson syndrome
Fluoroquinolones
- Inhibit DNA replication
- DNA gyrase & topoisomerase IV enzymes
- Bactericidal, broad spectrum
- UTI, soft tissue, osteomyelitis treatment
Isoniazid
- Tuberculosis treatment ONLY
- Inhibit mycolic acid synthesis (cell wall component)
Adverse Effects of Isoniazid
- Peripheral neuropathy
- Hepatotoxicity