Introduction to Antibiotics Flashcards
substances produced by various species of microorganisms that suppress the growth or destroy other microorganisms.
Antibiotics
What type anitbiotics directly kill bacteria. No functioning immune system required.
bactericidal
What type antibiotic requires an immune system to eliminate the pathogen?
Bacteriostatic
Do antibiotics fall neatly into bactericidal or bacteriostatic categories?
No, sometimes they can change at different doses
Do you want to combine bacteriostatic and bactericidal antibiotics?
No
What 4 types of antibiotics inhibit cell wall synthesis?
Penicillins
Cephalosporins
Bacitracin
Vancomycin
Do antibiotics only target pathogenic bacteria?
No- they can destroy normal flora as well leading to opportunistic infections
What are 2 main examples of bacterias that take over when you kill off normal flora.
Candida
Clostridium difficile
What antibiotics are part of the beta lactam antibiotics?
Penicillins
Cephalosporins
Carbapenems
Monobactrams
What are 4 agents that inhibit cell wall synthesis?
Penicillins Cephalosporins Cycloserine Vancomycin Bacitracin
What is an agent that acts directly on the cell membrane of the microorganism affecting permeability and leading to leakage of intracellular compounds.
Detergents (polymyxin)
What are the 2 ways antibiotics are used?
As an empirical therapy (broad spectrum)
As definitive therapy (choose selective therapy)
Why do you not want to continue broad spectrum antibiotics?
Will build resistance much faster
When should you get a culture?
Before starting antibiotic therapy
WIll you ever choose a bacteriostatic medication in an individual with a compromised immune system?
No, always choose bactericidial
Why does natural resistance occur?
Antibiotics fail to reach the target
Decreased permeability for cells that need to act on nucleic acid
lactamases deactivate beta-lactams
What does MRSA stand for?
Methicillin-resistant staphylococcus aureus
WHat are examples of 2 antibiotic resistance conditions.
MRSA
Mycobacteria tuberculosis
Why do cell wall inhibitors work so well?
Our cells don’t have walls so it targets cells that aren’t ours
What do cell wall inhibitors need to work?
Dividing bacteria (so don’t want to give something that also slows growth with it)
What is within the beta lactam compounds?
Penicillins Cephalosporins Carbapenems Monobactams Beta lactamase inhibitors
What is the beta lactam rings unstable to?
pH
beta-lactamases
What do the beta lactam drugs do in our bodies?
Undergo acetylation in our body
undergo a covalent bond with trans-peptidase
What 2 things are beta-lactam antibiotics generally?
Bactericidal
most active against growing organisms
What category are penicillins for pregnancy?
Category B (safe)
What was the original penicillin?
Penicillin G
Do beta lactam antibiotics work on organisms with no cell wall?
No
What is the most common way a beta lactam antibiotic develops resistance?
Develops beta-lactamase
What are the three ways for penicillins resistance?
inactivation by beta-lactamas
modification of PBP target
impaired penetration of drug to target PBP
What are the 2 types of penicillins?
Penicillin G or V
What kind of bacteria do Penicillin G and V work against?
Gram-positive cocci (except staphylococcus)
What type environment are beta lactam unstable in?
Acid environment
Can penicillin G be given orally?
No, because it isn’t stable in acid
What anaerobes species do penicillin G or V work against?
bacteroides species
fusebacterium species
What are some gram negatives that penicillins work against?
E. Coli H. influenzae N. gonorrhoeae Treponema pallidium and susceptible pseudomonas species
What are some infections that you treat with penicillins?
upper and lower respiratory tract
throat
skin
GU tract
What are penicillins used for prophylaxis for?
Dental procedures for those at risk of endocarditis
Gonorrhea or syphilis exposure
rheumatic rever
What are the 2 drugs within aminopenicillins?
Ampicillin
amoxicillin
What do aminopenicillins act on?
activity of Pen G plus improved covered of gram-negative cocci and Enterobacteriaceae
What is a problem with aminopenicillins?
A lot of the bacteria these are used to treat have develop beta lactamase activity.
What can you do to make aminopenicillins more effect on beta lactamse bacteria?
Add with beta-lactamase inhibitors
What is ampicillin combined with to make Unasyn?
sulbactam (a beta lactamase inhibitor)
What is found in augmentin?
amoxicillin + clavulanic acid (beta lactamase inhibitor)
What 2 types of bacteria do the combination of aminopenicillins and beta lactamase inhibitors work well against?
H. influenzae
Klebsiella sp.
What are three penicillinase- resistant penicillins? These drugs won’t work against MRSA
nafcillin
oxacillin
dicloxacillin
What is another name for penicillinase-resistant penicillins?
Antistaphylococcal penicillins
What are 3 antipseudomonal penicillins?
piperacillin
ticaricillin
carbenicillin (PO)
What do antipseudomonal penicillins treat?
Activity of Pen G pluse greater gram negative coverage including pseudomonas
coverage against- H. influenzae and Klebsiella
No covereaerd against treponema palladium or actinomyces
How can antipseudomonal penicillins treat gram-negative infections?
Combine with aminoglycosides
What is the only way piperacillin is available?
In combination with tazobactam (Zosyn)
What is the only way ticarcillin is found?
With clavulanic acid (Timentin)
What are three beta-lactamase inhibitors?
Clavulanic acid
sulbactam
tazobactam
The additional of beta-lactamase inhibitors helps to cover what?
H. flu
staph
moraxella catarrhalis
What penicillins are oral only?
Penicillin V
Amoxicillin w/ or w/o clavulanic acid
What type of penicillins are available PO and IV?
Nafcillin
Ampicillin
What penicillins are available IV only ?
ANtipseudomonal penicillins= piperacillin w/ or w/o tazobactam
What is a depot injection?
IM injection intended to be released overtime
What drug is given as a depot form and is drug of choice for syphilis?
Penicillin G
can many penicillins be administered orally?
No
What does food do to penicillins?
Decrease absorption of available oral penicillins
What ares do penicillins poorly penetrate to?
Eye
CNS
prostate
What is the only time where penicillins get into the CNS?
when meninges are inflamed
Are penicillins metabolized?
No, most are not just eliminated via kidney
How are pencillins eliminated?
Through kidney- filtered (10%) and actively secreted (90%) into the urine
What can block active secretion?
Probenecid
When do doses of penicillins need to be adjusted?
Renal insufficiency
What is serum sickness?
Urticaria, rash, fever, angioedema from penicillins
What are 2 idiosyncratic rxns of penicillins?
interstitial nephritis
hemolytic anemia
What is a big secondary infection with pencillins?
vaginal candidiasis
What can happen with oxacillin?
hepatitis
What is a side effect that can occur w/ nafcillin?
Neutropenia
What drugs do you not want to give with PCNs?
TCN or other bacteriostatic agents
anti-pseudomonal PCNs can affect ______ metabolism.
Warfarin
Cephalosporins are structurally similar to what?
penicillins
What is the mechanism of ceaphalosporins?
Bactericidial
inhibit bacterial cell-wall syntehsis
How many generations of cephalosporins are there?
5 generation
What category are cephalosporins in pregnancy?
Category B
What are the three ways you can get resistance to cephalosporins?
Mutations in PBP
production of beta-lactamases
alteration in cell-membrane porins in gram-negative bacteria
What are 1st generation cephalosporins similar to?
antistaph + aminopenicillins
What bacteria are 1st generation ceaphlosporins good for?
Aerogib gram-psoitive
above the diaphgram anaerobes
community acquired gram-negative organism coverage
What is the IV ceaphlosporin first generation?
Cefazolin (ancef)
What is the PO 1st generation cephalosporin?
Cephalexin (Keflex)
What is a huge prophylactic antibiotic for surgeries?
Cefazolin (Ancef)
What are 1st gen cephalosporins used for?
Septic arthritis
skin infections
acute otitis media
What are 2 classes within the second generation of cephalsporin?
Those with added gram-negative coverage
those with added anerobic coverage
What generation is better for gram positive? (ceaphlosporins)?
1st generation cephalosporins
What generation cephalosporin is better for gram negative?
2nd generation cephalosporins
What do 3rd generation cephalosporins have expanded coverage for?
Gram-negative coverage
penetration of BBB
What are 3 3rd generation cephalosporins that are avaliable PO?
cefpodoxine (vantin)
Cefdinir (omnicef)
Cefixime (suprax)
What is a 3rd generation cephalosporin that also has increased anti-pseudomonal coverage?
Ceftazidime (fortaz)
What do you use 3rd generation cephalosporins for?
Penicillin resistant pneumococcus meningitis penumonia in children and adults sepsis peritonitis UTI, skin infections, osteomyelitis N. gonorrhae
What is a 4th generation cephalosporin?
Cefepime (maxipime) IM/ IV
What are 4th generation ceaphlosporins good against (bacteria type)?
Gram-positive, gram-negative
anaerobic coverage
what do 4th generation cephalosporins treat?
intra-abdominal infection
respiratory tract infections
skin infections
What is a drug in the 5th generation of cephalosporin?
Ceftobiprole medocaril
What are 5th generation cephalosporins used for?
Treatment against MRSA
Do most cephalosporins have an oral admin option?
Yes
how are cephalosporins eliminated?
kidney
what cephalosporin (3rd generation) can lead to cholelithiasis?
ceftriaxone
What drug class can blood dyscrasias (idiosyncratic)?
cephalosporins
What 2 antibiotics (cephalosporin) have methylthiotetrazole side chains?
cefoperazone
ceftotetan
What can happen is someone take alcohol with cefoperazone and cefotetan?
disulfiram-like rxn with alcohol injection
Large amount of vomitting
hypoprothombinemia due to inference of synthesis of vitamin-K dependent clotting factors (concern with hemophiliacs or those on warfarin)
When will you get increased levels of cephalosporin serum levels?
With co-administration with probenecid
What is the most broad spectrum class of beta-lactam class of antibiotics (gram +, gram - coverage)? resistant to many beta-lactamases
Carbapenems
What are the three carbapnems?
ertapnem
imipenem-cilastin
meropenem
what should you reserve carbapenems be saved for?
Very severe infections
How is meropenem different from the other 2 carbapenems?
Greater activity against gram-negative
intra-abdominal infections
used for meningitis > 3 months of age
how are carbapenems administered?
parenterally
how are carbapenems excreted?
renally
What 2 drugs have cross-sensitivity to penicillins?
Carbapenem
cephalosporin
What carbapenem reduces valproic acid levels?
Meropenem
What category in pregnancy is mereopenem and ertapenem
category B
What category in pregnancy is imipenem/ cilastin?
Category C (means you consider risk vs. benefit)
What is the only monobactam available in the US?
Aztreonam (azactam)
What is the spectrum of monobactams?
gram-negative rods
Do monobactams have cross reactivity with PCN?
No
What can you use monobactams for?
Gram-negative infections
pneumonia, soft-tissue infections, UTI, intra-abdominal and pelvic infections
Do monobactams distribute to the meningens?
yes
How are monobactams excreted?
Kidneys
What category are monobactams?
Category B
Can monobactams be used in children?
Yes over 9 months
What is a cell wall inhibitor that is restricted to use as a secondary anti-tubercular drug?
Cycloserine
What are some ADRs of cycloserine?
CNS toxicity- reversible w/ pyridoxine
renal impairment will accelerate toxicity
why is cycloserine restricted for use?
highly susceptible to resistance
Does vancomycin act on the same site as beta-lactams?
No, but has same effect on cell wall synthesis
What are some bacteria that are resistant to vancomycin?
E. faecium (VRE)
some MRSA strains
What is vancomycin used to treat (resistant bacteria)
MRSA (but they are becoming more resistant)
What type bacteria does vancomycin work against?
Gram positive
What do we reserve vancomycin for?
Patients allergic to beta-lactams suffering from serious gram positive infections
Infections resulting from MRSA
When is the only time you give vancomycin PO?
If the patient has C. Diff
If vancomycin absorbed when given orally?
No
When can vancomycin get into the CNS?
When the meninges are inflamed
How is vancomycin metabolized and excreted?
Not metabolized, but 90% renal excretion
What is vancomycin half life directly dependent on?
ClCr
When do you need a dosage adjustment for vancomycin?
Marked renal insufficiency
What is the main indication for vancomycin?
MRSA or Staph Epi
includes endocarditis, sepsis, osteomyelitis, wound infections
also for pencillin resistant pneumococcus
What can happen if vancomycin is given too quicky?
Red man syndrome. Fix by slowing down infusion rate
What are 2 main adverse events of vancomycin? (also seen in aminoglycosides)
ototoxicity (non-reversible)
nephrotoxicity (reversible)
When is bacitracin nephrotoxic?
When given systemically, this is why its limited to topical use
Is bacitracin absorbed when given orally?
No, so can be used to irrigate GI
What are the components of Missouri irrigation solution?
Neomycin
Polymyxin
Bacitracin
