Broad Spectrum and Narrow Spectrum
Once a culture and sensitivity is complete, a narrow-spectrum/bacteria
specific drug can be used.
Antagonism: combination of 2 antibiotics that actually decrease the drug’s efficacy.
Multiple drugs therapy has potential to promote resistance.
Superinfections: occurs when micro-organisms that are normally present in the body
this flora serves purpose such as producing antibacterial substances and
competing with pathogenic organisms for space and nutrients.
Symptoms of superinfections include diarrhea, bladder pain, painful
urination and abnormal vaginal discharge.
Broad spectrum antibiotics are more likely to cause superinfections.
Discovered in 1941
Became a miracle drug preventing thousands of deaths.
Indicated in the treatment of: pneumonia, meningitis, skin bone and joint
infections, stomach infections, blood and heart valve infections, gas gangrene,
tetanus, anthrax, cicle cell anemia in infants.
Works by disrupting call walls, causing them to break down. Human cells do
not have cell wall thus action specific to bacteria.
Some bacteria develop resistance by secreting an enzyme called beta
lactamase or penicillinase.
This strain of bacteria has gently grown, limiting the effectiveness of
“Oxacillin” and cloxacillin work against penicillase producing bacteria.
Examples of commonly used Penicillins:
1. Penicillin G – Narrow spectrum
2. Cloxacillin- Narrow spectrum, penicillase resistant
3. Amoxicillin and Amoxicillin- Clavulamate (Clavulin)- Broad spectrum 4. Piperacillin Tazobactam (Tazocin)- Extended spectrum. Efective against
even more microbes (pseudomonas, enterobactera, klebsiella and
Nursing Care Penicillin’s
Up to 4% chance of allergic reaction with penicillin.
Avoid cephalosporin’s if patient has severe reaction to penicillin due to cross-
May alter sodium and potassium levels so watch carefully
Patients with impaired renal function may require smaller doses as majority
of penicillin is secreted through the kidneys.
Watch for bleeding with patient on anticoagulant therapy and penicillin
(extended spectrum penicillin’s) as they may interfere with platelet
Patients may develop antibiotic-associated psudomembranous colitis
(AAPMC). The organism clostridium difficile secretes a toxin that causes
severe inflammation of the bowel leading to necrosis.
Antidiarrheals should not be given, antibiotics discontinued and fluid and
Largest class of antibiotics organized in four generations
Isolated shortly after penicillin’s found
Also contains a beta-lactum ring that attack the penicillin binding protein to inhibit
cell wall synthesis.
Generally the treatment of choice against gram negative infections.
Example: cefazolin (Ancef) and cephalexin (Keflex)
Contain beta-lactum ring
Beta-lactamase bacteria will be resistant to this generation.
Fairly narrow range
More potent, more resistant to beta-lactamase and has a broad spectrum.