ANTIBACTERIALS- PART 1

Antibacterial MOAs (5)

1. Inhibition of cell wall synthesis

2. Increase bacterial cell permeability

3. Inhibition of protein synthesis

4. Inhibition of folic acid synthesis

5. Interference with DNA synthesis

What agents inhibit cell wall synthesis

BETA-LACTAMS:

-PCN

-Cephalosporins

- bacitracin

- vancomycin

what agents Increase bacterial cell permeability

Polymyxin B

What agents inhibit protein synthesis?

- Aminoglycosides

- tetracyclines

- macrolides

- chloramphenicol

- clindamycin

What agents inhibit of folic acid synthesis

Sulfonamides

what agents interfere with DNA synthesis

fluorinated quinolones

bactericidal vs bacteriostatic

bactericidal: killing, dont need immune system involvement

bacteriostatic: inhibit growth

Is it better to use an antibiotic specific for the organism or a wide/broad spectrum?

antibiotic specific to organism

better to be more NARROW than general

Overuse can result in disturbances of ____ can lead to ____

normal flora; superinfections

**** Exam Q: Which of the following antibacterial classes will affect the gut microbiome

all of them

Main cell wall inhibitors

Penicillin (PCN)

Cephalosporin

Cell wall inhibitors will mainly treat

Gram (+) bacteria (easy access to peptidoglycan)

-PCN cant access peptidoglycan in Gram (-) bc its in the middle layer

Cell wall inhibitors are not used as

topical agents

Antibacterials targeting cell wall synthesis are

selectively toxic to bacteria (wont harm humans)

***** EXAM Q: If someone has a PCN allergy, they will also react to

cephalosporin

what are PCNS used in

1. Acute dacryocystitis

2. Preseptal cellulitis

3. Internal hordeolum

Most PO (oral) penicillin should be taken

on an empty stomach

Which penicillin should be taken with food?

amoxicillin/clavulanate (Augmentin)

Natural Penicillin

Penicillin G (IV) & Penicillin VK (PO)

Natural Penicillin: Spectrum of Activity; what bacteria does it target

narrow spectrum

gram (+) cocci (non-resistant Staph and Strep spp.)

Antistaphylococcal Penicillins

-Nafcillin (IV)

-Dicloxacillin (PO)

-Methicillin

Drug of choice against sensitive Staph aureus—MSSA

Methicillin

Extended Spectrum Penicillins (Aminopenicillins)

Amoxicillin

Amoxicillin works against

gram+ (ie. non-resistant Staphylococcus and Streptococcus)

Amoxicillin used to treat

- Streptococcus pneumoniae at HIGH DOSES**

-Haemophilus influenzae

-Moraxella catharrhalis

Amoxicillin are

Typical organisms

Most common mechanism of resistance done by bacteria

beta lactamase production

examples of bacteria that produce beta lactamase

-Haemophilus influenzae

-Moraxella catharrhalis

beta-lactam/beta-lactamase inhibitors

Amoxicillin/Clavulanate (Augmentin)

which antibacterial is safe in pregnancy and breastfeeding

Amoxicillin + Clavulanic acid (Augmentin)

Extended Spectrum Penicillins (Anti-Pseudomonal)

Piperacillin (Pipracil)

Piperacillin (Pipracil) used to treat

Pseudomonas aeruginosa

PCN Side effects

- mild diarrhea

- 10% actually allergic to PCN (1% will have an actual response)

**** Exam Q: What indicates a severe reaction to penicillin

swollen eyes, swollen lips, itchy tongue, respiratory

**** Exam Q: a person with severe PCN allergy may cross react with

cephalosporin (3-10%

Cephalosporins MOA

inhibit terminal stage of cell wall synthesis

Cephalosporins are inactivated by

beta lactamase

Which generation of cephalosporin gives most GRAM + coverage, which gives most GRAM - coverage

1st Gen: Gram +

4th Gen: Gram -

Cephalosporin- 1st gen

Cefazolin (Ancef)

Cephalexin (Keflex)**

Cephalosporins treat...

-Streptococcus pneumoniae

-Haemophilus influenzae

-Moraxella catharrhalis

Cephalosporin- 2nd gen

Cefaclor (Ceclor) (oral)

Cefuroxime (Ceftin) (oral)

Cefoxitin --> cephamycin

Cephamycins effective against

anaerobes

Cephalosporin- 3rd gen

Cefixime

Cephalosporin ADRs

- hypersensitivity (rash, fever, bronchospasm, anaphylaxis)

- low cross sensitivity to PCNs

Examples of Bactericidal

Bacitracin

Bacitracin MOA

- inhibits stage 3 of cell wall synthesis

what does bacitracin cover

-gram (+): staph/strep, clostridiumgram

-gram (-) : N gonorrhea

what is a negative effect of bacitracin

renal toxicity

Bacitracin ADR

contact dermatitis

in regards to what we treat, what can bacitracin be used to treat

staph blepharitis

Vancomycin is a bactericidal that only works against

gram +

Vancomycin is _____ only for systemic infection

IV

Vancomycin is _____ only for gut infections

PO (oral)

is vancomycin a beta lactam

no

Vancomycin treats

MRSA

adverse effects of vancomycin

- ototoxicity and nephrotoxicity

- Red Man Syndrome

Two agents increase permeability of bacterial cell membrane

Polymyxin B

Gramicidin

what does polymyxin B treat/cover?

Pseudomonas

Adverse effects of topical polymyxin B

Irritation

Allergy

No significant systemic effects

30S protein synthesis inhibitors (AT)

Aminoglycosides

Tetracyclines

50S protein synthesis inhibitors (CELL)

Chloramphenicol

Erythromycin (Macrolides)

Lincosamide (Clindamycin)

Linezolid

generic name for azithromycin

topical agent for azithromycin

Generic: zpak

Topical: azasite

Topical azasite treats

Bacterial conjunctivitis

Meibomianitis

which antibiotics are used to treat meibomian gland dysfunction

azythromycin (high dose)

doxycyline (low dose)

what can macrolides treat PO?

Internal hordeolum

Are macrolides the drug of choice to treat internal hordeolum

no, unless pt has PCN allergy

Macrolide ADRs

GI upset

what can azithromycin cause in the heart

Arrhythmia, QTc prolongation

Azasite treats

bacterial conjunctivitis

Azasite ADR

eye irritation, burning, stinging

which drugs are safe to use in pregnancy, breastfeeding and in babies

PCN, cephalosporins and azithromycin