Exam 2 - Antibiotics Flashcards
**-cillin **
Drug Classification?
Example?
Penicillin antibiotic
EX: Amoxicillin
cef-, ceph-
Drug Classification?
Example?
Cephalosporin antibiotic
Ex: Cefazolin
-cycline
Drug Classification?
Example?
Tetracycline antibiotic
EX: Tetracycline
-floxacin
Drug Classification?
Example?
Fluoroquinolone antibiotic
EX: Levofloxacin
-thromycin
Drug Classification?
Example?
Macrolide antibiotic
EX: Azithromycin
-micin, -mycin
Drug Classification?
Example?
Aminoglycoside antibiotic
EX: Gentamicin
-azole
Drug Classification?
Example?
Antifungal
EX: Itraconazole
Describe some characteristics of the narrow spectrum antibiotic Penicillin G:
- Routes: IM, IV
- 3 different salts – potassium Pen G, Procaine Pen G, Benzathine Pen G
- Distributes well to most tissues and body fluids except the meninges and into fluids of joints and the eye. With inflammation, entry into the CSF, joints and eyes are enhanced.
- Effective against gas gangrene, tetanus, anthrax, syphillis, pneumonia, meningitis, strep throat, infective carditis
Describe some characteristics of the narrow spectrum antibiotic Penicillin V:
- Route: PO
- Stable in stomach acid
Describe the 1st generation of Cephalosporins
- destroyed by beta-lactamases
Cefazolin (Ancef) - rarely used for active infection
- As Effective as newer drugs
- Less expensive
- Have narrow antimicrobial spectrum
Describe the 2nd generation of Cephalosporins
- rarely used for active infection
- less sensitive to destruction Cefaclor (Ceclor)
- most effective against pneumonia caused by h. influenzae, Klebsiella, pneumococci & staphylococci
Describe the 3rd generation of Cephalosporins
- highly resistant to destruction Cefoperazone (Cefobid)
- Preferred therapy for several infections
- Highly active against gram-negative organisms
- Able to penetrate to cerebrospinal fluid (CSF)
- most effective against meningitis
Describe the 4th generation of Cephalosporins
- most highly resistant to destruction Cefepime (Maxipime)
- Broad spectrum
- Penetration to CSF is good
Describe the pharmacokinetics of tetracyclines
- Absorption – short acting, reduced by food, long acting (minocycline) not affected by food.
3 tetracyclines are affected by food:
- Chelation – tetracyclines form insoluble chelates with Ca++
- Avoid calcium supplements, milk products, iron supplements, magnesium-containing laxatives & antacids, zinc
- Should be taken on empty stomach: Give 2 h before or 2 h after chelating agents
- Elimination - by kidneys & liver; tetracycline & demeclocycline by kidneys*
Erythromycin is used as a durg of choice for what type of infections?
- Upper & lower respiratory tract infections
- Acute otitis media (AOM)
- GI infections
- Mycobacterium avium complex (MAC) infections in pts. with advanced HIV infection
How do microbes become resistant to Tetracyclines?
They become resistant from increased drug inactivation, decreased access to ribosomes (d/t presence of ribosome protection proteins), & reduced intracellular accumulation (d/t decreased uptake & increased export)
How must procaine and benzathine Penicillin G salts be administered to a patient?
intramuscularly
How would you give Ampicillin or Amoxicillin, broad spectrum penicillins, and what are some of their effects on the body?
Delivery:
- Ampicillin – IV, PO
- Ampicillin/sulbactam (Unasyn)
- Amoxicillin – PO
- Amoxicillin/clavulanic acid (Augmentin)
Side effects:
- Rash and diarrhea (most with ampicillin)
- Nursing teaching: Refrigerate oral suspensions
If a patient is allergic to Penicillin, why would the nurse be uneasy about administering cephalosporin’s or carbapenems to this patient?
Because 5-10% of people who are allergic to penicillin will also have a cross-sensitivity with cephalosporin’s or carbapenems.
Lab results for Mrs. Smith, the patient, came in and it was found that her urinary tract was infected by a bacteria that produces beta-lactamase. The doctor on staff ordered 500mg of Ampicillin IM every 6 hours to treat the infection. What should the nurse assigned to Mrs. Smith do when she receives this order?
- The nurse should know that Ampicillin & Amoxicillin are both inactivated by beta-
lactamases, and would thus be non-effective against the bacteria. The nurse should notify the doctor.
Nafcillin, Oxacillin, Dicloxacillin & Methicillin are narrow spectrum PCNase resistance antibiotics from the penicillin class of drugs. What are some characteristics of these antibiotics?
- Highly resistant to beta-lactamases
- Very narrow spectrum against penicillinase producing staphylococci (s. aureus & s. epidermidis)
- Methicillin – No longer avail. Causes interstitial nephritis (MSRA use Vancomycin
Resistance to PCN occurs in what 3 ways?
- Inability of PCN to reach their targets
- Inactivation of PCN by bacterial enzymes
- Production of penicillin-binding proteins (PBPs) that have a low affinity for penicillins
increThe nurse was given an order to administer 1 unit of Potassium Penicillin G IM to Patient X. Before administering the dose to the patient, the nurse should immediately realize what?
The nurse should know that Potassium Penicillin G can only be administered via IV and should not adminster the antibiotic.
What are beta-lactamases and what do they do?
- Beta-Lactamases cleave to beta-lactam rings & if specific to PCN’s they are called pencillinases.
- Gram-neg (Gm -) produce PCNase in small amounts and secrete them into the periplasmic space
- Gram-pos (Gm+) produce PCNase in large amounts and export it into the surrounding medium
What 3 drugs can be used as alternatives to PCN if someone is allergic to PCN?
- Erythromycin
- clindamycin
- vancomycin
- If previous mild allergic reaction to PCN, can be given cephalosporin -preferably oral dosing
- If past anaphylaxis reaction to PCN- avoid both PCN and cephalosporins
What are examples of Macrolides and what are some of their characteristics?
- Examples: Erythromycin, Clarithromycin, Azithromycin (-mycins)
- Broad-spectrum antibiotic (active against most gram-positive and some gram-negative bacteria)
- Usually bacteriostatic but can be bactericidal
- Similar to PCN (kills gm+ & some gm- & mycobacteria)
- Can use if allergic to PCN
What are some adverse effects of Vancomycin?
- Nephrotoxicity – major toxicity is renal failure – risk is dose-related and increased by use of other nephrotoxic drugs (aminoglycosides, cyclosporine, NSAIDs, etc.)
- Ototoxicity (reversible or permanent [if exceed 30mcg/ml])
- Red man syndrome — flushing, rash, pruritus, urticaria, tachycardia, hypotension
- Thrombophlebitis (common)
- Thrombocytopenia (rare)
- Allergy
- Narrow antimicrobial spectrum
What are some characteristics of Carbapenems?
- Beta-lactam antibiotic with an extremely broad antimicrobial spectrum & low toxicity
- Use is generally restricted to severe infections largely in hospitalized patients
- Not active against methicillin-resistant Staphylococcus aureus (MRSA)
- this drug is administered IV
What are some characteristics of penicillins?
- Active against a variety of bacteria
- Bactericidal
- Direct toxicity: low – one of the safest abx
- Beta-lactam ring in their structure is what causes allergic reactions in people.
- Beta-lactam family: also includes cephalosporins, aztreonam, imipenem, meropenem, and ertapenem
- PCN eliminated by kidneys
- Renal impariment can lead to toxic levels
- High concentration PCN can inactivate aminoglycosides (example gentamicin)
What are some characteristics of the Broad spectrum penicillins (Aminopenicillins)?
- Ampicillin & Amoxicillin – both inactivated by beta-lactamases
- Same spectrum as Pen G (narrow spectrum) but also active against more gm- (h. influenzae, e. coli, Salmonella & Shigella)
What are some characteristics of narrow spectrum Penicillin drugs?
- PCNase sensitive
- Bactericidal to numerous gram-positive and some gram-negative organisms
What are some characteristics of Cephalosporins?
- Most widely used group of antibiotics
- Are beta-lactam antibiotics – similar to PCNs MOA
- Similar to penicillin structure
- Bactericidal
- Usually given parenterally
- Toxicity is low
- 4 generations
- Susceptible to Beta-lactamases
What are some characteristics of Clarithromycin?
- gen’l same as erythromycin
- Available in tablets, ER tabs (Biaxin XL) & granules)
ER take with food others with or without - USED TO TREAT: Respiratory tract inf., uncomplicated skin inf., H. pylori, Mycobacterium avium in HIV inf.
- Adverse reactions: Metallic taste, cardiac arrhythmias
What are some characteristics of Extended Spectrum PCN’s (Antipseudomonals)?
- susceptible to beta-lactamases and therefore ineffective against S. aureus
- Used against P. aeruginosa, often occurring in immunocompromised pts
- both can cause bleeding from disrupting platelet function
- both can cause sodium overload (more for ticarcillin)
- do NOT mix PCNs w/ aminoglycosides in the same IV solution b/c PCNs can inactivate aminoglycoside
What are some drug interactions with cephalosporins?
- Probenecid – delays renal excretion
- Alcohol – cephazolin, cefmetazole, cefoperazone & cefotetan
- Drugs that promote bleeding – cefmetazole, cefoperazone & cefotetan (check prothrombin time)
- Calcium and ceftriaxone combo
List and describe the 2 narrow spectrum Penicillins that are PCNase sensitive?
- PCN G (IM, IV)
- PCN V (PO)
What are the 3 mechanisms of bacterial destruction?
- Cell wall disruption -
- Enzymatic inhibition
- Protein synthesis disruption
What are the 4 members of the tetracycline family?
- Tetracycline – short-acting
- Demeclocycline – intermediate-acting
- Doxycycline – long acting
- Minocycline – long acting
- All similar in strux, abx actions, and AEs
- Different pharmocokinetics
What are the 5 narrow spectrum penicillins that are PCNase resistant & antistaphyloccocal?
- Methicillin
- Nafcillin
- Oxacillin
- cloxacillin
- dicloxacillin
What are the 6 Extended-spectrum penicillins (antipseudomonal PCN’s)?
- carbenicillin (PO)
- ticarcillin (IV)
- mezlocillin
- Piperacillin
- Ticarcillin/clavulanate (IV)
- Piperacillin/tazobactam (IV)
What are the adverse affects of tetracyclines?
- Gastrointestinal irritation – burning, cramps, N&V, diarrhea
- Effects on bone and teeth – bind to Ca++ in developing permanent teeth (4mos – 8 yo) resulting in yellow/brown discoloration
- Suprainfection – issues with all broad spectrum ab. DIARRHEA*
- C. difficile a.k.a. antibiotic-associated pseudomembranous colitis Renal toxicity – tetracycline & demeclocycline elim by kidneys
- Photosensitivity
- High-dose IV therapy associated w/ severe liver damage esp. pregnant & postpartum women with kidney ds
What are the adverse effects of televancin?
- taste disturbance, nausea, vomiting, foamy urine
- Red man syndrome
- Kidney damage – measure function at baseline, q 72 hrs during tx, and at end of tx
- Prolong QT interval
What are the adverse effects of Cephalosporins?
- Allergic rxns – hypersensitivity rxns (maculopapular rash, days after onset of tx is most common); severe rxns are rare
- Bleeding – cefmetazole, cefoperazone, cefotetan, & ceftriazone
- Thrombophlebitis - phlebitis
- Hemolytic anemia [antibodies (Abs) mediate destruction of RBCs] - rarely
What are the characteristics of Narrow spectrum, PCNase resistant antibiotics.
Nafcillin, Oxacillin, Diloxacillin & Methillin
- Highly resistant to beta-lactamases
- Very narrow spectrum against penicillinase producing staphylococci.
- Methicillin is no longer avaliable. Causes interstitial nephritis.
What are the four methods microbes use for drug resistance?
- Decrease the concentration of a drug at its site of action
- Alter drug target molecules (receptors)
- Produce drug
- Drug inactivation
What are the mechanisms of action of Carbapenems?
- Binds to 2 PBPs (PBP1 & PBP2) weakening cell wall causing lysis & death
- Resistant to almost all beta-lactamases & has ability to penetrate gm- microbes
- Elimination – primarily renal
- Interaction with Valproate – can reduce blood levels of valproate (used to control seizures)
What are the nursing interventions when administering Vancomycin?
- Monitor serum drug levels – check peak and trough levels
- Dosage should be adjusted to achieve effective TROUGH serum levels
What are the pharmacokinetics of Cephalosporins?
- Almost all renally excreted – except ceftriazone (liver)
- 5-10% cross resistance with PCN
- Dose usually based on duration of action (DOA)
- Refrigerate oral suspension
What are the uses of Vancomycin?
- Drug of choice for MRSA: Methicillin-resistant Staphylococcus aureus or Staphylococcus epidermidis (most strains are still sensitive to vanc
- Severe infections only – severe Clostridium difficile (C. diff) infection (CDI) [oral dosing – vanc not absorbed from GI tract*
- Oral dose used for C. diff if metronidazole was tried and found ineffective
What are the 5 broad spectrum pencillins ((aminopenicillins)?
- ampicillin (PO, IV)
- amoxicillin (PO)
- bacampicillin
- Ampicillin/sublactam
- Amoxicillin/clavulanate
What are the 7 major specific MOAs for anti-infectives?
- Disrupt the cell wall or activate enzymes that disrupt the cell wall
- Increase cell wall permeability
- Lethal inhibition of protein synthesis
- nonlethal inhibition of protein synthesis
- Inhibit DNA or RNA synthesis or disrupt DNA function
- Antimetabolites
- suppress viral replication
What are Tetracyclines method of action?
- Inhibit bacterial synthesis* which suppresses cell growth & replication but are only bacteriostatic. These are mostly 2nd line agents when infections are resistant to 1st line agents.
- Selective toxicity to microbes*
What does Vancomycin do?
- Inhibits cell wall synthesis by binding to molecules that serve as precursors for cell wall synthesis (not PBPs)
- ONLY active against gm+ bacteria
- NO beta-lactam ring – so can use on pts allergic to PCNs*
- Eliminated by kidney*
What is the mechanism of action for Macrolides?
inhibition of protein synthesis (50S ribosomal subunit)*
What are the mechanism of action for Cephalosporins?
- Bind to penicillin-binding proteins (PBPs), disrupt cell wall synthesis, and cause cell lysis
- Most effective against cells undergoing active growth and division
What is the MOA of penicillin?
- Weaken cell wall which causes cell wall to take up excessive water & rupture through activation of autolysins and inhibition of transpeptidases
- Only effective against cells that are undergoing growth and division
- Most effective against gram positive bacteria
What problem could a Calcium and ceftriaxone combo cause in a neonate?
- This can form fatal precipitates (solids that fall out in sol’n) in lungs & kidneys
- Don’t give through the same line OR different lines unless 48 hours between them
- In pts other than neonates IV cephtriaxone and Ca++ may be administered through the same line sequentially (not at the same time), but must flush between sol’ns
With each new generation of Cephalosporins what 3 things are noticed?
- Increasing activity against gm- bacteria
- Increasing resistance to beta-lactamases
- Increasing ability to reach the cerebral spinal fluid (CSF)
