Antibiotics 1 & 2 Flashcards
Bacteria groups: Aerobic gram-positives
Staph
Streptococcus
Enterococci
Listeria
Bacteria groups: Aerobic or facultative gram negatives
Enterobacteriacease
Neisseria
Peudomonas
Haemophilus
Bacteria groups: Anaerobes
Clostridum Actinomyces Peptostreptococcus Bacteroids Fusobacterium Prevotella
Bacteria groups: Atypical/intracellular
Mycoplasma Chlamydia Legionella Mycobacterium Rickettsia Spircochetes
What bacteriocidals target cell walls?
B-lactams
Vancomycin
Daptomycin (cell membrane)
What bacteriostatics inhibit growth or replication (RNA synth)?
Rifamycin
What antibiotics block protein synthesis?
Aminoglycans
Macrolides
Tetracyclins
What antibiotics target DNA or DNA synth?
Quinolones
Metronidazole
What is the anti-metabolite antibiotics?
Trimethoprim-sulfamethoxazole
What are some B-lactams that works on gram positives and some gram negatives?
Penicillins
Cephalosporins
Carbapenems
Monobactams
What cell wall inhibiting antibiotics are good from gram positives?
Vancomycin
Daptomycin
What cell wall inhibiting antibiotics are good for TB?
Isoniazid
Ethambutol
Pyrazinaminde
What is the mechanism of action for B-lactams?
They bind to transpeptidases (PBPs) (which catalyse cross linking of peptidoglycan residues) and block the reaction resulting in weak cell walls
What kinds of bacteria are natural penicillins active against?
Streptococcal species (GAS, GBS, viridans)
Most gram-positive anaerobes
Treponema pallidum
What strep group is resistant to natural penicillin?
S. pneomoniae
What is the action of anti-staph penicillin?
They have large R-groups which make them resistant to staph b-lactamases
What are some types of anti-staph penicillins?
Nafcilllin, Oxacillin, Dicloxacillin
What are anti-staph penicillins active against?
MSSA - methicillin sensitive staph aureus
MSSE - methicillin sensitive staph epidermidis
What are the 2 types of aminopenicillians?
Ampicillin and Amoxicillian
What does the addition of an amino group to an R chain make aminopenicillins effective against gram-negatives?
Allows for penetration through porins (especially rods)
Aminopenicillins are effective against many of the same things as natural plus:
E. coli, shigella, salmonella burgdorfi
What antibiotics are included in the extended spectrum penicillins?
Piperacillin, ticarcillin, carbenicillin
What can extended spectrum do better than aminopenicillin?
It can better penetrate gram-negative porins
Extend spectrum penicillins are effective against many of the same things as natural plus:
More enterobacteriaceae and some strains of p. aeruginosa
What is a beta-lactamase?
Enzymes with specific activity against beta-lactams
What combination can be used as a beta-lactamase inhibitors?
Aminopenicillin and extend spectrum
How does a b-lactamase inhibitor work?
The b-lactam ring acts as a decoy for the lactamases and then IT STRIKES
What bacteria have b-lactamases?
S. aureus, H. influenzae, N, gonorrhoeae, many enterobacteriaceae, certain anaerobes
What antibiotics are b-lactamase inhibitors?
Clavulanic acid
Sulbactam
Tazobactam
What are some B-lactamases combined with aminopenicillins?
Amoxicillin + Clavulanate = Augmentin
Ampicillin + Sulbactam = Unasyn
What are some B-lactamases combined with extended spectrum penicillins?
Piperacillin + tazobactam = Zosyn
Ticarcilllin + Clavulanate = Timentin
What are some of the problems with the toxins related to penicillins?
Hypersensitivity, can activate a hapten becoming immunogenic after binding to RBC
What signs occur with a type 1 hypersensitivity to penicillin?
Skin rashes and anaphylaxis
What signs occur with a type 2 hypersensitivity to penicillin?
Drug-induced hemolytic anemia
What are some characteristics of Cephalosporins and Cephamycins?
More resistant to b-lactamases than natural penicillins
Wider spectum of activity that naturals
Generational
Not particularly useful against anaerobes or intracellular organisms
What are the first generation Cephalosporins and Cephamycins?
Cefazolin and cephalexin
What is the second generation Cephalosporins and Cephamycins?
Cefuroxime
What is the third generation Cephalosporins and Cephamycins?
Ceftriaxone
What is the fourth generation Cephalosporins and Cephamycins?
Cefepime
What in the “generalization” about Cephalosporins and Cephamycins?
With increaseing generation activity in vitro against aerobic gram-positives decreases while activity against gram-negatives increases
What are the first generation Cephalosporins and Cephamycin used for?
They are similar to aminopenicillin and used for minor skin and soft tissue infections and UTIs
What is the second generation Cephalosporins and Cephamycin used for?
Used against gram-positive spectrum plus acitivty agisnt E. coli, Klebsiella, Proteus, H. influenzae and Neisseria
What is the third generation Cephalosporins and Cephamycin used for?
They are moderately active agisnt aerobic gram positives (MSSA) plus activity against aerobic gram negatives, with modified R chains and can cross through the blood-brain barrier
What is the fourth generation Cephalosporins and Cephamycin used for?
Retains some third generation spectrum, activity against pseudomonas, inc affinity to PBP and can penetrate porins better, poor activity against anaerobes
What are some types of Carbapemems?
Imipenem, meropenem, ertapenem
How do carbapemems rank as a spectrum drug?
Among the most broad spectrum
Compared to other b-lactams, Carbapemems;
Have improved penetration of porins, enhanced binding to PBP and inc resistance to b-lactamases
What are some clinical uses of Carbapemems?
Useful against Pseudomonas
What is special about Imipenem?
It was the “hail mary” of drugs and can be combined with cilastatin (called Primaxin) to inhibit renal dihydropeptidase
What types of bacteria are Carbapenems effective against?
Many bacteria, broad spectrum, useful against Pseudomonas, resistant to B-lactamases
What bacteria are Carbapenems not effective against?
MRSA, Clostridium difficile and Burkholdreia cepacia
Which is the only licensed drug in the Monobactam group?
Aztreonam
Because the R groups are attached directly to the B-lactam ring, what special ability does it have?
Ability to penetrate porins and bind to gram negative PBP
What type of safety situations can Aztreonam be used for?
Used for patients with penicillin allergies and patients with renal disease
Does Aztreonam have what type of spectrum of activity? And which bacteria are effected?
Narrow Moraxella Neisseria Enterobacteriaceae Pseudomonas Haemophilus Burkholderia
What are some of the adverse reactions to B-lactams?
Penicillin binding to proteins or RBCs to become immunogenic, rashes to anaphylaxis, hemolysis
If someone has adverse reactions to penicillin should they be given cephalosporins?
NO
If a person has a CNS disease what could happen if they were given a Carbapenem?
Seizures
How could a bacteria be resistant to B-lactams?
Penetrations (Intracellulars) Porins Pumps (efflux) Penicillinases (B-lactamases) Penicillin-binding proteins Peptidoglycan (lack of)
What does it mean when a bacteria is intrinsically resistant to an antibiotic?
The resistance is a constitutive part of the bacterial species - naturally resistant
What is bacterial acquired resistance to a antibiotic?
Resistance formed by mutations, phage transduction and aquiring genes from another bacterial strain/species (transformation, conjugation)
What are some altered cephalosporins and cephamycins and how are they modified?
MRSA and Pneumococci (penicillin binding protein) Pseudomas aeruginosa (efflux pump)
What does Vancomycin inhibit cell walls?
Binds to the D-ala-D-ala building block of peptidoglycan
With a narrow spectrum of activity, what does Vancomycin work against?
MRSA, penicillin resistant S. pneumo and certain enterococcal infections
How does enterococci make itself resistant to Vancomycin?
Changes the D-ala-D-ala to D-ala-D-lac
When should you use Daptomycin?
For aerbic gram-positives
MRSA, penicillin resistant S. pneumo and vancomycin resistant enterococci
What does Daptomycin not effective against?
Gram negative bacteria
