Anti-Infective Agents
Antibiotics:
Sulfonamides
Penicillins
Cephalosporins
Tetracyclines
Aminoglycosides
Macrolides
Quinolones
Antibiotics
Medications
used to treat bacterial infections
Culture
and sensitivity before therapy
Antibiotics Definitions
Empiric
therapy: treatment of an infection
before culture
Prophylactic
therapy: treatment with antibiotics
to prevent an infection
Broad
spectrum- effective against several groups of microorganisms
Narrow
spectrum- effective against a few groups
Antibiotics Definitions
Bactericidal:
kill bacteria
Bacteriostatic:
inhibit growth of susceptible bacteria, rather than killing them immediately;
will eventually lead to bacterial death
Superinfection:
elimination of normal bacteria and other bacteria take over
Nosocomial
Hospital
Acquired Infections
Patients
with decreased resistance
Often
drug resistant strains
Staph
(Skin, Lungs)
Psuedomonas
(Lungs, Wounds)
Proteus
(Wound, UTI)
http://www.fda.gov/fdac/features/2002/402_bugs.html
Antibiotic Resistant Microorganisms
Antibiotics: Sulfonamides
One of the first groups of antibiotics
sulfadiazine
sulfamethizole
Sulfamethoxazole
sulfisoxazole
Sulfonamides: Mechanism
of Action
Bacteriostatic
action
Prevent
synthesis of folic acid required for synthesis of purines and nucleic acid
Does
not affect human cells or certain bacteriathey can use preformed folic acid
Sulfonamides: sulfamethoxazole
Therapeutic Uses
Bactrim
Combined
with trimethoprim.
Used
to treat UTIs, Pneumocystis carinii pneumonia, ear infections, bronchitis,
gonorrhea, etc.
Sulfonamides: Side
Effects
Photosensitivity
Crystalluria
Delayed
skin reactions
Antibiotics: Penicillins
Natural
penicillins
Penicillinase-resistant
penicillins
Aminopenicillins
Extended-spectrum
penicillins
Penicillins
Inhibit
the synthesis of bacterial cell wall
Bactericidal
Therapeutic
levels are not usually obtained in intraocular and cerbrospinal fluid
Rapidly
excreted in through the kidneys
Antibiotics: Penicillins
First
introduced in the 1940s
Bactericidal:
inhibit cell wall synthesis
Kill
a wide variety of bacteria
Also
called beta-lactams
Antibiotics: Penicillins
Bacteria
produce enzymes capable of destroying penicillins.
These
enzymes are known as
beta-lactamases.
As
a result, the medication is not effective.
Antibiotics: Penicillins
Chemicals
have been developed to inhibit these enzymes:
clavulanic
acid
These
chemicals bind with beta-lactamase and prevent the enzyme from breaking down the
penicillin
Prototype: Penicillin G
Widely
used
Effectiveness
and minimal toxicity
Available
IV & IM
Natural
PCN
Antibiotics: Penicillins:
Augmentin
Penicillin-beta-lactamase
inhibitor combination drugs:
amoxicillin
+ clavulanic acid = Augmentin
Inactivate
beta-lactamase enzymes
Protects
PCN and extends spectrum
Available
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: Therapeutic
Uses
Prevention
and treatment of infections caused by susceptible bacteria
Penicillins: Adverse
Effects
Allergic
reactions occur in 0.7% 8% of treatments
urticaria,
pruritus, angioedema
10%
of allergic reactions are life-threatening
and
10%
of these are fatal
Penicillins: Side
Effects
Common
side effects:
nausea,
vomiting, diarrhea, abdominal pain
Other
side effects are less common
Antibiotics: Cephalosporins
First
Generation
Second
Generation
Third
Generation
Fourth
Generation
Antibiotics: Cephalosporins
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
cefazolin
cephalexin
(Ancef and Kefzol)
(Keflex and Keftab)
IV and
used for surgical prophylaxis,
Cephalosporins
Prototype: Cephalexin (Keflex)
Broad
spectrum
First
generation
Respiratory,
soft tissue, bones, urinary tract, and bloodstream infections
Tx
pcn resistant GC
Contraindicated
with prior severe anaphylactic reaction to PCN
Cephalosporins: Side
Effects
similar
to penicillins
Antibiotics: Tetracyclines
doxycycline
(Doryx, Doxy-Caps, Vibramycin)
Antibiotics: Tetracyclines
Natural
and semi-synthetic
Bacteriostaticinhibit
bacterial growth
Inhibit
protein synthesis
Stop
many essential functions of the bacteria
Tetracyclines: Therapeutic
Uses
Wide
spectrum:
gram-negative,
gram-positive, protozoa, Mycoplasma, Rickettsia,
Chlamydia, syphilis, Lyme disease
Antibiotics: Tetracyclines
Bind
to Ca2+ and Mg2+ and Al3+ ions to
form insoluble complexes
Thus,
dairy products, antacids, and iron
salts reduce absorption of tetracyclines
Tetracyclines: Side
Effects
Strong affinity for calcium
Discoloration
of permanent teeth and tooth
enamel in fetuses and children
May
retard fetal skeletal development if taken
during pregnancy
Tetracyclines: Side
Effects
Alteration in intestinal flora may result in:
Superinfection
(overgrowth of nonsusceptible organisms such as Candida)
Diarrhea
Pseudomembranous
colitis
Tetracyclines: Side
Effects
May also cause:
Vaginal
moniliasis
Gastric
upset
Enterocolitis
Maculopapular
rash
Antibiotics: Aminoglycosides
gentamicin
(Garamycin)
Aminoglycosides
Natural
and semi-synthetic
Poor
oral absorption; no
Very
potent antibiotics with serious toxicities
Bactericidal
Kill
mostly gram-negative; some
gram-positive also
Aminoglycosides
Used
to kill gram-negative bacteria such as Pseudomonas spp., E. coli, Proteus spp.,
Klebsiella spp., Serratia spp.
Often
used in combination with other antibiotics for synergistic effect.
BIG
GUN!!!!
Aminoglycosides
Cause serious toxicities:
Nephrotoxicity
(renal failure)
Ototoxicity
(auditory impairment and vestibular [eighth cranial nerve])
Must
monitor drug levels, pg 581
Adverse Effects Aminoglycosides Page 583
Nephrotoxicity
Ototoxicity
Neurotoxicity
Hypersensitivity
Aminoglycosides: Side Effects
Ototoxicity and nephrotoxicity are
the most significant
Antibiotics: Quinolones
ciprofloxacin
(Cipro)
Quinolones
Excellent
oral absorption
Absorption
reduced by antacids
First
oral antibiotics effective against
gram-negative bacteria
Quinolones: Mechanism
of Action
Bactericidal
Effective
against gram-negative organisms and some gram-positive organisms
Alter
DNA of bacteria, causing death
Do
not affect human DNA
Quinolones: Therapeutic
Uses
Lower
respiratory tract infections
Bone
and joint infections
Infectious
diarrhea
Urinary
tract infections
Skin
infections
Sexually
transmitted diseases
Quinolones: Side
Effects
Dizziness
Photosensitivity
Constipation
Rash,
pruritis
Drug Interactions
Cimetidine
Probenicid
Antacids
Iron
Antibiotics: Macrolides
erythromycin
azithromycin
(Zithromax)
Macrolides: Therapeutic
Uses
Strep infections
Streptococcus
pyogenes
(group A beta-hemolytic streptococci)
Mild to moderate URI
Haemophilus
influenzae
Spirochetal infections
Syphilis
and Lyme disease
Gonorrhea, Chlamydia, Mycoplasma
Macrolides: Side
Effects
GI effects, primarily with erythromycin:
nausea,
vomiting, diarrhea, hepatotoxicity,
flatulence, jaundice, anorexia
Newer
agents, azithromycin and clarithromycin: fewer side effects, longer duration of
action,
better efficacy, better tissue penetration
Antibiotics: Nursing
Implications
Before
beginning therapy, assess drug allergies; other labs
Be
sure to obtain thorough patient health history,.
Assess
for conditions that may be contraindications to antibiotic use
Assess
for potential drug interactions.
Antibiotics: Nursing
Implications
It
is ESSENTIAL to obtain cultures from appropriate sites BEFORE beginning
antibiotic therapy.
Antibiotics: Nursing
Implications
Patients
should be instructed to take antibiotics exactly as prescribed
Assess
for signs and symptoms of superinfection:
Fever
Cough
Perineal
itching
Sore
throat
Antibiotics: Nursing
Implications
Check
the name of the medication carefully since there are many agents that sound
alike or have similar spellings.
Antibiotics: Nursing
Implications
Each
class of antibiotics has specific side effects and drug interactions that must
be carefully assessed and monitored.
The
most common side effects of antibiotics are nausea, vomiting, and diarrhea.
All
oral antibiotics are absorbed better if taken with at least 6 to 8 ounces of
water.
Antibiotics: Nursing
Implications
Sulfonamides
Should
be taken with at least 2400 mL of fluid
per day, unless contraindicated.
Due
to photosensitivity, avoid sunlight and
tanning beds.
These
agents reduce the effectiveness of
oral contraceptives.
Antibiotics: Nursing
Implications
Penicillins
Monitor
for 30 minutes.
The
effectiveness of oral penicillins is decreased when taken with caffeine, citrus
fruit, cola beverages, fruit juices, or tomato juice.
Antibiotics: Nursing
Implications
Cephalosporins
Orally
administered forms should be given with food to decrease GI upset, even though
this will delay absorption.
Some
of these agents may cause an Antabuse-like reaction when taken with alcohol.
Antibiotics: Nursing
Implications
Tetracyclines
Avoid
Milk
Iron
antacids
6
to 8 ounces of fluid, preferably water.
Due
to photosensitivity, avoid sunlight and
tanning beds.
Antibiotics: Nursing
Implications
Aminoglycosides
Monitor
peak and trough blood levels
Symptoms
of ototoxicity
dizziness,
tinnitus, and hearing loss.
Symptoms
of nephrotoxicity
urinary
casts, proteinuria, and increased BUN and serum creatinine levels.
Antibiotics: Nursing
Implications
Quinolones
Should
be taken with at least 3 L of fluid per day, unless otherwise specified
Antibiotics: Nursing
Implications
Macrolides
These
agents are highly protein-bound and will cause severe interactions with other
protein-bound drugs.
Antibiotics: Nursing
Implications
Monitor for therapeutic effects:
Disappearance
of
Fever
Lethargy
Drainage
Redness