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Antibiotics: Part II
Introduction to
Antibiotics: Part II
• Cephalosporins
 1st generation
 2nd generation
 3rd generation
 4th generation
Sulfonamides
Lincosamides
Aminoglycosides
Fluroquinolones
Oxazolodinoes
Miscellaneous


Vancomycin
Metronidazole
Drugs to Know
Cephalosporins
Sulfonamides
Lincosamides
Aminoglycosides
Narrow spectrum
Narrow spectrum
Antibacterial & antiprotozoa
Very potent
Serious SE!
clindamycin (Cleocin) po, IV
Neomycycin
Effective against bacteria AND
protozoa
amikacin (Amikin) IV
beta lactam abx
4 generations
cephalexin
(Keflex) PO 1st
trimethoprim + sulfisoxazole
(TMP/SMP, Bactrim) po
cefazolin Ancef
IV 1st
garamycin/Gentamicin
cefuroxime
Ceftin
PO 2nd
cefoxitin Mefoxin
IM/IV 2nd
cefixime Suprax
PO 3rd
cefitraxone
Rocephin
IM/IV 3rd
cefepime
Maxipime
IV 4th
NARROW THERAPEUTIC INDEX
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More Drugs to Know
Fluoroquinolones
Oxazolidinones
Misc Agents
ciprofloxacin (Cipro)
IV/PO
linezolid (Zyvox)
vancomycin
(Vancocin)
levofloxacin (Levaquin)
IV/PO
IV / PO
Considered the
“last line drug”
IV/po
Formerly the “last line
drug”
Requires ‘peak &
trough’ levels
metronidazole
(Flagyl)
IV/PO
Abx and antiparasitic
CEPHALOSPORINS
 The cephalosporins are divided into four generations
which progressively become broader spectrum

Look for “cef” prefix
 Like penicillins, many cephalosporins have a
beta-lactam structure
 The first generations of cephalosporins are sensitive
to betalactamase producing bacteria

Thus, these drugs are RENDERED INEFFECTIVE by bacteria that produce
betalactamase
Adverse Reactions:
Cephalosporins
(all generations)
 Low toxicity, well
tolerated
 Adverse Reactions
 Hypersensitivity (similar
Increased bleeding by
interfering with vitamin K
metabolism. Monitor PT/INR

may occur up to 72H
after last dose (delayed
reaction)
to and 10% cross-reactive with
penicillin hypersensitivity)


*GI (N-V-D)
ANTABUSE EFFECT
(interaction with ETOH)

Nephrotoxicity
Adverse reactions

Prolonged use may cause a
superinfection
What is the Antabuse
Effect?
disulfiram/Antabuse
Is a drug that increases the sensitivity to alcohol
Discovered in the 1920’s

Used to support the treatment of chronic alcoholism

Blocks the processing of alcohol in the body by inhibiting
acetaldehyde dehydrogenase
Causes INTENSE negative effects of alcohol
 N/V, H/A, dizziness
 Some drugs (cephalosporins and Flagyl) may cause
this same effect when taken with ETOH
Cephalosporins: therapeutic uses
Indications VARY
depending on
generation
Treatment of mild to
severe skin infections



Cellulitis–mild to severe
Often d/t strep or staph
URI and pneumonia
Surgical prophylaxis
Meningitis
A fairly mild skin
infection
(cellulitus)
Could be tx with a
1st generation
cephalosporin
such as Keflex
A serious soft tissue
infection that would
require the use of 2nd
generation such of
Mefoxin
1st Generation Cephaloporins
1st generation
NARROW SPECTRUM
Good gram (+) coverage. Poor gram (-) coverage

MINIMALLY effective against betalactamase producing bacteria
Indications:

Used to treat UTIs, SIMPLE skin infections, strep throat

Can be used for surgical prophylaxis
ALTERNATIVE TO PENICILLIN (mild allergy only) for staph and strep
infections
(Keflex)
cefazolin sodium (Ancef)

PO: cephalexin

IM/IV:
2nd Generation Cephalosporons
2nd generation
BROADER SPECTRUM

good gram (+) AND good gram (-) coverage
But limited application b/c NOT effective against betalactamase
producing bacteria
Indications:

Used to treat septicemia, bone and joint infections, and
respiratory infections
 PO: cefuroxime (Ceftin) otitis, sinusitis, and respiratory tract infections

IM/IV: cefoxitin sodium (Mefoxin)
infections
 abdominal and pelvic
3rd Generation Cephalosporins
3rd generation:

NARROW spectrum

Good for gram (-) infections only



nosocomial infections mostly d/t gram (-) infections
able to penetrate the CSF (meninigitis)
MINIMALLY effective against beta-lactamase bacteria
DOES CROSS BLOOD BRAIN BARRIER!!

PO: cefixime (Suprax)

IM/IV: ceftriaxone

(Rocephin)
Rocephin has a long half life and can be given once or twice a day
4th generation Cephalosprins
4th generation:
BROADEST spectrum


Effective against MOST gram (+) and gram
AND… Able to resist MOST beta-lactamase
producing bacteria
CROSSES BLOOD BRAIN BARRIER!!

Is effective against MRSA and enterobacter

IM/IV: cefepime (Maxipime)
IV
SULFONAMIDES
 Indications:
 Sulfonamides are
commonly Rx for UTIs
MOA - inhibit the
synthesis of folic
acid
 Achieve high
concentration in the
KIDNEYS (UTI’s)
 May be used as an
alternative for clients
allergic to penicillin
Bacteria use folic
acid to synthesize
their DNA
Indications: Sulfa drugs are
commonly used to treat
urinary tract infections
cystitis
Pyleonephritis
Normal kidney
Sulfonamides
Indications:
Narrow spectrum

Most common – UTI’s and Chlamydia, pneumocytis carinii
pneumonia, rheumatic fever
Caution: cross sensitivity with THIAZIDES and
SULFONYLUREAS

**Patient allergic to sulfa antibiotics may also be allergic to thiazides and/or
diabetic sulfa containing drugs
Sulfonamides
Common drugs:
Trimethomprim

Bacteriostatic when used alone

Commonly used WITH SULFA for synergistic effect
rendering them bacterocidal

* trimethroprim + sulfisoxazole

(Septra
, Bactrim)
(TMP/SMP)
SULFONAMIDES
 Adverse Effects

*Anorexia, N-V-D
photosensitivity

Crystalluria (kidney

stones can form)


Interactions:
displaces protein bound
anticoagulants  clotting
times (PTINR) toxic to the
kidney (need to drink lots!)
Bone marrow
suppression, hemolytic
anemia



Renal failure
Skin rashes
Hypersensitivity – vascular
lesions, rash, eruptions, drug
fever
Encourage lots of water
Sulfa drugs can be toxic to
the kidney.
Lincosamide
clindamycin/Cleocin is effective against BOTH bacteria
and PROTOZOA such as trichomoniasis
Indications:

Used to tx diseases of the skin, vagina, resp tract and abdomen

Is effective against skin infections d/t MRSA!

Is a powerful inhibitor of toxin synthesis

Often used WITH a bacteriocidal agent

As the bacteriocidal agent and toxins are released the clindamycin inhibits the
toxin formation
SE: Frequently causes C. diff colitis!!
Lincosamides
MOA: inhibits
bacterial protein
synthesis

Bacterostatic at low
doses and bacterocidal
at higher doses
clindamycin
(Cleocin)

NARROW SPECTRUM

Indications:


Used to treat gram (+)
infection, including staph,
and anaerobic organisms
SE:



*N-V-D
Rash
Colitis (c dif) and
anaphylactic shock
What does a MRSA
infection look like?
MRSA can look like a spider bite, a boil, pustules.
It can get into the lungs causing pneumonia, into the bladder/kidney causing UTI,
or can cause serious blood borne infections. MRSA can be fatal!
AMINOGLYCOSIDES
Destroy bacteriatrue bactericidal agents

IV only

Cannot be given po d/t poor absorption
Indications:

Used to treat SERIOUS INFECTIONS d/t aerobic bacilli and
gram (-) organisms
*Very potent and capable of serious side effects!!
Nursing Alert: Do not mix in the same container with
penicillins and cephalosporins
Aminoglycosides
MOA: Inhibits bacterial protein synthesis Bactericidal

NARROW SPECTRUM

Only active against gram (-) bacteria

Pseudomonas
Indication:

Primarily used in nosocomial infections
Aminoglycosides (cont)
Do not penetrate CSF
Cross the blood brain barrier in children but not
adults
Excreted RENALLY by glomerular filtration
**Narrow therapeutic index drug**


*Requires constant monitoring
“PEAK/TROUGH LEVELS”
What is a Peak and
Trough level?

PEAK = greatest concentration of
the drug in the BLOOD (30 min
AFTER infusion)

TROUGH = greatest concentration
of the drug in the TISSUE (30 min
PRIOR to next infusion)

Therapeutic levels are desired

Risk for serious SE increases with
high trough levels
High trough levels? – the next
dose may be held and peak and
trough repeated
Aminogylcosides
Potential Serious Adverse Effects

Ototoxicity – vestibular and auditory


may be irreversible
Nephrotoxicity – potentially reversible

 BUN & Creatinine

Both toxicities dependent on HIGH
“TROUGH” LEVELS
Aminoglycosides
*gentamicin sulfate (Garamycin) – available in
topical, opthalmic, and IV forms

amikacin



(Amikin): (IV only) –
often used to rx infections resistant to gentamicin, little
resistance so far to Amikin
neomycin (Mycifradin) – a milder aminoglycoside
Indications:


suppress GI bacteria pre-op (colon surgery)
a topical agent to treat wound infections
Pseudomonas infection:
serious infections
Pseudomonas infections are
resistant to many antibiotics
Quinolones/Fluoroquinolones
MOA: interfere with bacterial DNA
Bacteriocidal

Quinolones developed first
Have a narrow spectrum
 Seldom used today

Fluoroquinolones developed by
adding a fluorine atom to basic
quinolone structure

BROADER SPECTRUM
What infections are floroquinolones
commonly prescribed for?
Indications:

Many gram (-), some anerobes, atypicals


Good for people allergic to erythromycin (EES)



UTIs, bone and joint infections, bronchitis, pneumonia,
gonorrhea
Enterobacter, Pseudomonas, MRSA
Now seeing FQRP (fluoquinolone resistant pseudomonas)
Accumulates well in urine and prostate
Florquinolones
Adverse Effects:

Both serious and
bothersome:
 N-V-D, dyspepsia

H/a, dizziness, rashes

Hepatotoxicity
(LFTs)
Drug Interactions

Can inhibit
theophylline and
warfarin metabolism
increasing the levels
of these drugs
Fluoroquinolones
Look for “floxacin” suffix
Common drugs

*ciprofloxacin (Cipro) PO and IV

levofloxacin (Levaquin) PO and IV
** NURSING ALERT** IV Levaquin is sensitive
to light and will break down if exposed to light
 use a brown plastic bag to cover IVPB
What is the hype about
Vancomycin?
NARROW SPECTRUM GM (+)


Vancomycin is used IV to treat serious infections (MRSA) and
Enterococci
Vancocin is used po to treat C. difficile colitis
Was previously considered the LAST RESORT DRUG
Resistance is now being noted to infections caused by
Enterococcus (VRE) and staph aureus (VRSA)
Super Bug is resistant to Vancomycin
Miscellaneous Agent:
Vancomycin
vancomycin IV (Vancocin) PO

A glycopeptide antibiotic structurally different
from other available antibiotics
 SE:
(potential and serious)
 Petechiae and Thrombocytopenia


Ototoxicity and nephrotoxicity
 Peak and trough levels periodically monitored
Rapid IV administration can cause “RED
SYNDROME”
MAN
What is Red Man Syndrome?
An ADR to vancomycin IV that
may occur with the FIRST dose
of vancomycin ,OR when the
drug is administered TOO FAST
Sx: flushing of face and neck,
pruritus, hypotension
Prevention: slow the rate of
infusion

Vancomycin should be given
over AT LEAST lH

higher doses often ordered
over 90 min
If Red Man Syndrome develops, the nurse should
stop the infusion and notify the HCP.
Benadryl is often ordered to decrease the effect of
the reaction.
Vancomycin
Resistance Enterococci (VRE)
Oxazolidinones
Newer class of antibiotic
Indication:

Developed in 1999 primarily to treat vancomycin -resistant
enterococcus (VRE)

Enterococci is a gram (+) bacterium in our GI tract that can be highly aggressive
, esp in post-op pts
Enterococci causes UTI, septicemia, endocarditis and infects wounds

Oxazolidinones are also used to treat infections d/t MRSA

Is now considered “THE LAST LINE ANTIBIOTIC”
Oxazolidinones
linezolid (Zyvox) (po,IV)

Inhibits bacterial protein synthesis

New “Last line drug”

Adverse effects:
 *Pseudomembranous colitis (C. Difficile
colitis)
Misc Antibiotic:
metronidazole/Flagyl
Flagyl is considered both an ANTIBIOTIC
and an Anti-parasitic agent

Indications:


Flagyl is commonly prescribed to treat infections d/t
anaerobic bacteria and some protozoa
Also, commonly used for abdominal and pelvic
infections; as well as liver abcess
More Indications:
metronidazole/Flagyl
Indication:
 Flagyl is also the first line treatment for
C. diff colitis

an anerobic bacteria that causes profuse diarrhea in
some patients who take certain antibiotics
Adverse Reactions: Generally well
tolerated

Antabuse effect may occur if ETOH
consumed while taking Flagyl.