Abx Flashcards
Indirect pathogen spread
pathogen spread to person from a contaminated object
Exotoxins
proteins released by bacteria that inactivate or kill host cells
Endotoxins
– non-protein released from cell wall of Gram-negative bacteria that elicit immune responses
Cause macrophages to release cytokines
Pathogen Ability to evade host defenses
Capsules to prevent phagocytosis
Antigenic shift and drift to avoid detection by immune system
- changing how they look
Inducing endocytosis to hide certain bacteria in host cells
Resistance to anti-infective medications
Resistance to anti-infective meds occurs by
Pathogen modifies drug target site
Pathogen modifies uptake of drug by altering its capsule, cell wall or membrane
Pathogen inactivates drug
If bacteria stain purple they are
Gram positive
If the stain is red or pink the bacteria is
Gram negative
Bacteria classed by
Staining property
Shape
Ability to use O2
Which bacteria are easier to klil based on O2 requiredments
Anearobic
Promotion of resistance occurs by
Bacteria change physiology to become resistant by:
Replicating rapidly
Mutating spontaneously and randomly
Acquiring resistance and promoting resistance to other bacteria via conjugation
Transfer of small pieces of DNA called plasmids that contain resistance promoting gene
Mechanism of anti-infectives are
Bacteriocidal
Bacteriostatic
Four main sources for spreading of HAIs
Patient flora in skin, lungs, urinary tract
Invasive devices such as catheters and endoscopes
Medical personnel – pathogens are spread by healthcare workers
Medical environment – pathogens can survive outside of host environment; spread on clothing
Vancomycin-resistant enterococci (VRE)
Found in wounds and pressure ulcers in hospitals and nursing homes
Patients with weakened immune systems at most risk
Methicillin-resistant Staphylococcus aureus (MRSA)
Resistant to certain antibiotics
At least 60% of MRSA infections resistant to penicillin
Most often acquired in hospital
Usually occurs in patients with weakened immune systems
Therapy options are limited.
Guidelines for Antibiotic Therapy (1 of 2)
Where possible, use (C&S) testing to identify the organism, and then the appropriate antibiotic
If not possible to do C&S, begin with a broad spectrum antibiotic then use a narrow-spectrum antibiotic
Broad spectrum are effective against many types of bacteria but affect host flora
If infection caused by one microbe, treat-ment with _______ is usually best
a single drug
Combining antibiotics can _________
decrease their effectiveness and promote resistant strains
Patient factors affect choice of anti-infective.
Host defenses and immune system status
Local tissue conditions – for some infections, it is difficult to get a therapeutic concentration to site of infection
Allergy history and drug hypersensitivity
Pregnancy, age, genetics
Superinfections
(secondary infections) develop when host flora is damaged by antibiotic as nutrients and space become available for pathogens to grow
Host flora being in competition with each other for space and nutrients is called microbial antagonism
Broad spectrum abx are more likely to cause
Broad spectrum antibiotics are more likely to cause superinfections
B Lactam Abx
Breaks down peptogylyvan molecules in cell walls of bacteria, allowing fluid to enter causing cell lysis and death.
- Penicillin, cephalosporins, carapenems
Tetracycline, macrolides
Bacteriostatic, inhibit protein synthesis
Flourquinolones, macrolides,
Prevent DNA replication of pathogens
Sulphonamides action
Inhibit DNA replication due to inhibition of folate
Vancomyocin action
Inhibit cell wall synth damaging cell wall allowing fluid to enter and cause lysis of cell
For acute infections choosing the wrong antibiotic for just a few days even hours can lead to
a poor prognosis or death.
For the correct antibiotic to be chosen you need to know the ________ ________.
Causative agent
How do we find the causative agent?
Specimens
How do we then determine the most effective antibiotic?
Culture and sensitivity test
If infection is severe treatment is usually started with a ________ ________ antibiotic.
Broad spectrum
B-lactam abx most effective against what kind of pathogens
G+
How do bacteria become resistant against peniciliin
They mutate so they lack the penicillin-binding proteins that are the target of penicillin’s
They secrete an enzyme (penicillinase or beta-lactamase) that splits penicillin’s beta-lactam ring, often in response to penicillin
Penicillins
Mostly effect G+
Narrow spectrum
Wide distribution except CNS (CSF)
Short half life
Extended Spectrum have an additional advantage (Pseudomonas Aeruginosa) next slide
Adverse effects of Penicillin
N/V/D
Most serious
Anaphylaxis
Piperacillin/Tazobaxtam (Piptaz)
Antibioticpiperacillinand theβ-lactamase inhibitortazobactam.
The combination has activity against manyGram-positiveandGram-negativebacteria.
Those who are allergic to anotherβ-lactamare more likely to be allergic to piperacillin/tazobactam.
Abx associated pseudomembranous colitis
A serious super infection caused by c-difficile secreting a toxin that causes severe inflammation of the bowel followed by necrosis.
Can be life threatenin
Cephalosporins
Largest abx classs
Primaryly for G+ and some G-
Broad spectrum
Can be toxic to kidneys
Beta lactam
Ceftriaxone
Broad spectrum
Beta lactam abx
Mainly used to treat harder to treat infections
Ceftriaxone used for
Bacterial endocarditis(an infection of the heart)
Bacterial meningitis(inflammation of tissues surrounding the brain and spinal cord)
Bacterial otitis media(middle ear infection)
Bacterial sepsis(a severe immune overreaction to infection)
Bacterial skin infection
Bacterial urinary tract infections
Bone and joint infections
Community-acquired pneumonia
SJS
Life threatening rash that can progress into toxic epidermal necrolysis which causes skin to slough off
Cephalosporin Prototype Drug Cefotaxime
Broad spectrum activity against G-
Can cause rash, diarreah, pain at injection sites, anaphylaxis, and seizure
Carbapenems
Broad-spectrum antibiotics with similar properties to other beta-lactam antibiotics (they are resistant to beta lactamase)
Better activiity against seriious G- multidrgu resist infections
The Big Guns
Must be given IV
Ex. Meropenem
Tetracyclines
One of the broadest spectrum of any class of abx
Bacteriostatic
Decrease effectiveness of Birth control
Tetracyclines adversities
SHould be taken on empty stomach
Often remain in GI tract killing normal flora producing diarrhea
Can be hepatotoxic
Do not take with Ca and Iron products
Discolouration of teeth
N/V/D, epigastric burning
Phtosenesitivy
Macrolides
Most effective against Gram-positive bacteria
Alternative drugs for patients allergic to penicillin
Generally well tolerated and safe
Bacteriostatic in low doses, can bacteriocidal in high doses
Most adverse effects are GI related
Mech of Erythromycin
Inhibits protein synthesis
Considered bacteriostatic, but may be bacteriocidal in high doses
Adverse effects of macrolide
Hepatotoxicity
Anaphylaxis
Otoxicity (hearing loss, vertigo, dizziness)
Cardiotoxicity
Azithromycin
Newer macrolide
Causes less GI irritation
Longer half life so?
More expensive but brief duration of therapy thought to increase client adherence
Aminoglycosides
Only given IV
Bactericidal
VERY poorly absorbed PO
Certain tissues bind Aminoglycosides tightly, renal excretion may be prolonged for up to 20 days after discontinuation, serum drug levels may fall but they still may exhibit minimal antibiotic activity. This is called the
Post abx effect
Aminoglycoside waht spectrum
Broad
Can be used in meningitis
Aminoglycoside adverse effects
NVD
Serious adverse effects
Ototoxicity
Nephrotoxicity
Neuromuscular blockage
Neurotoxicity
Fluoroquinolones
Fluoroquinolones work by preventing DNA replication, bactericidal
G- action with some G+
Favorable safety profile
NVD common side effect
Can also affect CNS (Dizziness, headache,s and sleep disturbances)
Ciprofloxacin (Fluroquinolone)
Prevents DNA replication
Rapidly absorbed after oral administration
Caffiene to be avoided
May increase effect of Warfarin
Ciprofloxacin most often used for
UTIs
Sulfonamides
Broad spectrum
Adverse effects include formation of crystals in urine, hypersensitivitys rxns etc
Sulfonamides use for
UTI prophylaxis and UTI
Vancomycin
Adverse effects: Red man syndrome (Flushing, HOTN, tachycardia, rash) in upper body
What causes red man syndrome
Vancomycin administered IV too quickly, treated with Benydril
Nursing consideration when administer abx IV
Monitor for 30 minutes closely for rxn
Monitoring for clients on abx therapy
Monitor for severe diarrhea (indicating possible superinfection, or pseudomembranous colitis)
Monitor intake of OTC drugs that may affect absorption of antibiotics (antacids, Ca and Mg supplements, Fe supplements)
Determine possible drug interactions
Monitor for adverse effects specific to each antibiotic drug class
Monitor for signs of photosensitivity, ototoxicity, nephrotoxicity associated with specific antibiotic drug classes
Monitor IV sites for………
Monitor compliance of patient with drug administration schedule
Pharmacotherapy for UTIs
Sulfonamides
Fluoroquinolones
Given PO, only reach effective conc in kidneys
Nitrofurantoin adverse effects
Adverse effects
Hypersense rxn
N/V, Diarrhea
Headache
Rash
Serious adverse effects
Hepatotoxicity
Acute and chronic pulmonary toxicity
TB
Tuberculosis caused by Mycobacterium tuberculosis, spread via airborne droplets
Immune system response leads to formation of tubercles in lungs that surround mycobacteria (visible on x-ray)
In healthy person, mycobacteria remain dormant, person is asymptomatic
If immunocomprimised infection becomes active
Two major goals of therapy of TB
Eliminate all tubercle mycobacteria
Avoid emergence of resistant strains
DOT
Directly observed therapuy
- must watch pt take meds
It is ESSENTIAL to obtain cultures from appropriate sites _____ beginning antibiotic therapy:
BEFORE
