Ch. 29 Penicillins Flashcards
What determines the shape of bacteria?
The structure of the cell wall
Which organism is elongated or rod-shaped?
Bacilli
Which organism is spherical?
Cocci
What are cocci that appear in clusters called?
Staphylococci
What are cocci that are arranged in chains called?
Streptococci
What are bacteria classified as if they retain a purple stain?
Gram-positive microorganisms
What are the bacteria that are not stained called?
Gram-negative microorganisms
List some examples of gram-positive bacteria.
Staphylococcus aureus, streptococcus pneumoniae, group B streptococcus, and clostridium perfringens
List some examples of gram-negative bacteria.
Neisseria meningitides, E. coli, and Haemophilus influenzae
What causes cell lysis (cell death)?
Toxins produced by bacteria
What enzyme is produced by many bacteria?
Beta-lactamase
What is the function of the enzyme beta-lactamase?
Destroys beta-lactam antibiotics
List the beta-lactam antibiotics.
Penicillins and cephalosporins
What is the function of bacteriostatic drugs?
Inhibit growth of bacteria
What is the function of bactericidal drugs?
Kill bacteria
What are the 5 mechanisms of antibacterial action are responsible for the inhibition of growth or destruction of microorganisms?
(1) Inhibition of cell wall synthesis, (2) Alteration in membrane permeability, (3) Inhibition of protein synthesis, (4) Inhibition of synthesis of bacterial RNA & DNA, & (5) Interference with cellular metabolism
What may be depleted in individuals with poor nutritional status that’s needed to combat infections?
Immunoglobulins (antibody proteins such as IgG & IgM) and WBCs
What occurs if bacteria are resistant to an antibacterial?
The pathogen continues to grow, despite administration of that antibacterial drug
List the 4 types of resistance to antibacterials.
Natural or inherent resistance, acquired resistance, nosocomial infections, and cross- resistance
Define natural or inherent resistance.
Occurs without previous exposure to the antibacterial drug
Define an acquired resistance
Caused by prior exposure to the antibacterial
Explain how an antibiotic resistance occurs.
As bacteria reproduce, some mutation occurs, and eventually the mutant bacteria survive the effects of the drug
What is one explanation as to why an organism becomes resistant to antibiotics?
The mutant bacteria strain may have grown a thicker cell wall
Define a nosocomial infection.
Infections acquired while clients are hospitalized
Define cross-resistance.
Occurs between antibacterial drugs that have similar actions, such as the penicillins and cephalosporins
What can be done to ascertain the effect antibacterial drugs have on a specific microorganism?
Culture and sensitivity (C&S) or antibiotic susceptibility testing is performed
Why would a C&S be done?
It can detect the infective microorganism present in the sample and what drug can kill it
Why would an antibiotic susceptibility test be done?
The susceptibility or resistance of one microorganism to several antibacterials can be determined.
What can delay the development of microorganism resistance?
Multiantibiotic therapy (daily use of several antibacterials)
What are 3 results when 2 antibiotics are combined?
Additive, potentiative, and antagonistic
When might a combination of 2 or 3 antibiotics be suggested?
When there is a severe infection that persists and is of unknown origin or has been unsuccessfully treated with several single antibiotics
Describe the additive effect of combination antibiotics.
The antibiotic effect is doubled.
Describe the potentiative effect of combination antibiotics.
One antibiotic potentiates (enhances or increases) the effect of the other, increases effectiveness
Describe the antagonistic effect of combination antibiotics.
If the combination of antibiotics is one bactericidal and one is bacteriostatic, then the desired effect is diminished
What are the 3 major adverse reactions associated with the admin of antibacterial drugs?
Allergy or hypersensitivity, superinfection, and organ toxicity
What are some mild allergic reactions to antibacterials?
Rash, pruritus, hives (may be a delayed reaction)
What does a severe allergy to an antibacterial result in?
Anaphylactic shock
What are the s/s of anaphylactic shock?
SOB, bronchospasm, laryngeal edema, vascular collapse, and cardiac arrest
Which symptom of anaphylactic shock is frequently the first symptom?
SOB
What is the treatment for a mild allergic reaction to an antibiotic?
An antihistamine
What are the treatments for a severe allergic reactions (anaphylactic shock) to an antibiotic?
An antihistamine, epinephrine, and a bronchodilator
When does a severe allergic reaction to an antibiotic occur?
Generally occurs within 20 minutes
What is a superinfection and when does it occur?
A secondary infection that occurs when the normal microbial flora of the body are disturbed during antibiotic therapy
Where can superinfections occur?
The mouth, respiratory tract, intestines, genitourinary tract (vagina), or skin
What type of infections frequently result in superinfections, although bacterial organisms may be the offending microorganism?
Fungal infections
When would a superinfection occur during antibiotic therapy?
Usually occurs when treated with antibiotics for more than 1 week
In which organs can toxicity occur during antibiotic therapy?
Ears, liver and kidneys
What is a narrow spectrum antibiotic?
Primarily effective against one bacterial type
List 2 narrow spectrum antibiotics.
Penicillin and erythromycin (gram-positive)
What is a broad spectrum antibiotics?
Effective against gram-positive and gram-negative
List 2 broad spectrum antibiotics.
Tetracycline and cephalosporins
When might a pt receive a broad spectrum antibiotic?
Before surgery to prevent post-op infections
When is a broad spectrum antibiotic used instead of a narrow spectrum antibiotic?
To treat infections when the offending microorganism has not been identified by C&S
Describe the structure of penicillins.
Beta-lactam structure (beta-lactam ring) interferes with bacterial cell-wall synthesis
What is the purpose of the structure of penicillin?
Inhibits the bacterial enzyme that is necessary for cell division and cellular synthesis. The bacteria die of cell lysis (cell breakdown)
What were basic penicillins introduced to kill?
Staphylococcus
Is a basic penicillin a narrow-spectrum or a broad-spectrum antibiotic?
Narrow-spectrum antibiotic
What is the expected pharmacological action of penicillins?
To destroy bacteria by weakening the bacterial cell wall
List 4 examples of basic penicillins.
Penicillin G procaine (Crysticillin, Wycillin), penicillin G benzathine (Bicillin), penicillin G sodium/potassium (Pfizerpen), and penicillin V potassium (Veetids)
What is the -suffix associated with penicillins?
Suffix -cillin
What are penicillins mainly referred to as?
Beta-lactam antibiotics
What are the beta-lactamases, which attack penicillins called?
Penicillinases
Name the bacterial enzyme that destroys penicillin.
Penicillinase
Which penicillins are used to treat both gram-positive and gram-negative bacteria?
Broad-spectrum penicillins
List some gram-negative bacteria that is treated with broad spectrum antibiotics
E. coli, H. influenzae, S. dysenteriae, P. mirabilis, and Salmonella
Are broad spectrum antibiotics bacterostatic or bactericidal?
Bactericidal
What are broad spectrum antibiotics also known as?
Aminopenicillins
What does it mean that broad spectrum antibiotics are not penicillinase resistant?
They are readily inactivated by beta-lactamases, thus ineffective against S. aureus
List 2 examples of broad spectrum antibiotics.
Amoxicillin (Amoxil) and ampicillin (Omnipen)
What are penicillinase-resistant penicillins (antistaphylococcal penicillins) used to treat?
Peniscillinase-producing S aureus
Which gram stain are penicillinase-resistant penicillins effective at treating?
Gram-positive
Are penicillinase-resistant penicillins or basic penicillins more effective at treating gram-positive bacteria?
Basic penicillins
Are penicillinase-resistant penicillins bacterostatic or bactericidal antibiotics?
Bactericidal
What are penicillinase-resistant penicillin antibiotics also known as?
Antistaphylococcal penicillins
List 3 examples of penicillinase-resistant penicillins.
dicloxacillin sodium (Dynapen), nafcillin (Nallpen), oxacillin sodium (Bactocill)
What are extended spectrum penicillins also known as?
Antipseudomonal penicillins
Antipseudomonal penicillins are a part of what group?
Broad spectrum penicillins
What are extended spectrum penicillins effective in treating?
Gram-negative organisms
Which gram-negative organisms does extended spectrum penicillins treat?
Pseudomonas aeruginosa, Proteus, Klebsiella pneumoniae
Are extended spectrum penicillins bacterostatic or bactericidal?
Bactericidal
What type of infections do extended spectrum penicillins treat?
Bone, joint, skin, soft tissue, respiratory tract and urinary tract infections
What are 3 examples of extended spectrum penicillins (antipseudomonal penicillins)?
piperacillin (Pipracil), ticarcillin (Ticar), and carbenicillin (Geopen)
What are beta-lactamase inhibitors?
A broad spectrum antibiotic is combined with a beta-lactamase (enzyme) inhibitor
What is the action of a beta-lactamase inhibitor in combination with a broad spectrum antibiotic?
The resulting antibiotic inhibits the bacterial beta-lactamases, making the antibiotic effective and extending it antimicrobial effect
What are the 3 beta-lactamase inhibitors?
clavulanic acid, sulbactam, and tazobactum
What are the peniclillinase-sensitive penicillins that are combined with the beta-lactamase inhibitors?
amoxicillin, ampicillin, piperacillin, or ticarcillin
Name the oral beta-lactamase inhibitor.
Amoxicillin-clavulanate (Augmentin)
What is the benefit of combining amoxicillin and clavulanate?
The combo intensifies the effects of the amoxicillin
What are the 3 parenteral beta-lactamase inhibitor antibiotics and what is the benefit of combining them?
piperacillin-tazabactam (Zosyn), ticarcillin-clavulanate (Timentin), and ampicillin-sulbactam (Unasyn). The combination extends the spectrum
What needs to be monitored in a parenteral beta-lactamase inhibitor antibiotic?
Irritation, rashes, red streaks up the arm (phlebitis), and allergic reactions
What must be done prior to administering an antibiotic?
Check C&S (testing of infective organism)
What are the s/s of a superinfection?
Stomatitis (mouth ulcer), genital discharge (vaginitis), and anal or genital itching
What medications are used to treat a superinfection while on antibiotic therapy?
fluconazole (Diflucan) or Nystatin
What needs to be monitored for especially after the first and second doses of antibiotics?
An allergic reaction to the penicillin product
What must you have available to counteract a severe allergic reaction to penicillin antibiotic therapy?
Epinephrine
Why do you not mix aminoglycosides with a high dose or extended spectrum penicillin G?
This combination may inactivate the aminoglycosides
Why would you check for bleeding if high doses of penicillin are being given?
A decrease in platelet aggregation (clotting) may result
Why would you encourage the patient to increase their fluid intake while on penicillins?
Fluids aid in decreasing the body temperature and in excreting the drug
Should penicillins be taken with or without food?
Usually taken on an empty stomach; 1 hr before or 2 hrs after a meal. May be taken with food to avoid gastric irritation
What is the first assessment that needs to be done prior to administration of penicillins?
Assess for allergy to penicillin or cephalosporins
When do you monitor a patient for allergies/anaphylaxis during treatment with parenteral penicillin?
30 minutes following administration
What do you advise a patient with allergies to PCN to wear?
A medication alert (MedicAlert) bracelet or necklace
Why is it so important to assess renal function with PCN therapy?
Most beta-lactam antibiotics are excreted via the kidneys
What labs should be monitored to assess renal function during PCN therapy?
Serum BUN and serum creatinine
What is done to the PCN antibiotic dose if there is a decrease in renal function?
The antibiotic dose should be decreased
What else besides labs need to be monitored to assess renal function during PCN therapy?
Monitor I&O
Which broad spectrum penicillins may decrease the effectiveness of oral contraceptives?
Amoxicillin and ampicillin
Why would you monitor cardiac status and serum electrolyte levels in patients receiving PCN antibiotics?
Hyperkalemia/dysrhythmias are possible with high doses of penicillin and penicillin G
Why would you exercise caution with patients who follow a sodium-restricted diet during PCN therapy?
Hypernatremia may occur with IV carbenicillin and ticarcillin
Why would you administer probenecid (Probalan) during PCN therapy to prolong antibacterial action?
Probenecid (Probalan) delays excretion of PCN
What are some food interactions with PCN antibiotics?
Decrease affect with acidic fruits or juices
What changes in lab values might you see during PCN antibiotic therapy?
Increases serum AST, ALT, BUN and creatinine
How does aspirin effect amoxicillin and dicloxacillin therapy?
Increases the effect of the penicillin antibiotics
What are common adverse reactions to penicillin administration?
Hypersensitivity and superinfection
What are some common GI disturbances during PCN administration?
N/V and diarrhea
What does amoxicillin treat?
Respiratory tract infections, UTIs, otitis media, and sinusitis
What does dicloxacillin treat?
Staphylococcus aureus infections
