Anti-Infective Agent (Ch.7)

what is bacteria

what is it not

what does it not have

"prokaryotes" (as opposed to eukaryotes); no organelles and no organized nucleus

what are aerobic bacteria

- survive and grow in an oxygenated environment

what are anaerobic bacteria

- do not require oxygen for growth

what are obligate anaerobes

some bacteria that react negatively or even die if oxygen is present

what are antibiotics

drugs targeting processes that are essential for bacterial growth and survival

define bacteriostatic

stops their growth

define bactericidal

kills the cell

define bacteriolytic

destroys (lyses) bacteria

Define virulence

ability to produce disease

Define prophylaxis

prevention of disease

Which patient population is recommended to receive prophylactic antibiotics prior to dental treatments?

patients with a high risk of developing infective endocarditis

Define antibiotic resistance

what is caused by

the ability of bacteria to withstand the effects of an antibiotic

- usually caused by subtherapeutic antibiotic doses

What are the most common side effects of antibiotics?

and what organ system

GI distress: stomach pain, increases motility & diarrhea

Which antibiotic are safe safe for pregnant women?

penicillin & erythromycin

Which antibiotic are NOT safe for pregnant women?

tetracyclines

What is the mechanism of antibacterial action of penicillins?

they inhibit synthesis of the bacterial cell wall

define narrow spectrum antibotics

effective only against gram-positive OR gram-negative bacteria

define broad spectrum antibotics

antibiotics that are effective against both gram-negative & gram-positive bacteria

What are the mechanism by which bacteria develop resistance to antibiotics?

enzymatic inactivation or alteration of target sites

expalin enzymatic inactivation from β-lactamase (penicillinase)

β-lactamase (penicillinase) hydrolyzes penicillins and cephalosporins → Drug inactive

explain enzymatic inactivation from Acetyltransferases

Acetyltransferases inactivate chloramphenicol, aminoglycosides, and tetracyclines

what is the target site fluoroquinolones usally binds to that gets altered by bactera

enzymes called DNA gyrase and topoisomerase

what is the target site tetracyclines, macrolides, and clindamycin) usally binds that gets altered by bactera

ribsomes

what is the target site viridans group streptococci (VGS) and pneumococci (β-lactam antibiotics). usally binds to that got altered by bactera

➢Modified penicillin-binding proteins (PBPs)

If a patient is allergic to penicillin, the patient is likely to be also allergic to which class of drugs? why (2)?

cephaloaporins or other beta lacatams because 5-10% of patients have cross allergies

- patients previously treated with beta lacatams are more likely to have a rx

What is penicillinase (or beta-lactamase) function and how does it provide resistance to penicillin to bacteria?

destroys some penicillins by cleaving the beta-lactam ring; prevents penicillin from reaching the PBPs (penicillin-binding protein)

What does it mean for a drug to have penicillinase-resistance'?

The antibiotic is immune to being broken down by penicillinase

Why are penicillins widely used? 4

1. bactericidal potency

2. lack of toxicity

3. spectrum of activity

*very effective against aerobic & anaerobic bacteria*

How do penicillins work? and why Which part of the bacteria do they target?

Penicillin binds to penicillin-binding proteins (PBPs: involved in cell wall synthesis) which inhibits the formation to cross-linkages (peptidoglycans) > destroys cell wall > lysis

What are the two major drug interactions common in antibiotics?

oral contraceptives: clearance of contraceptions from the body

oral anticoagulants: clindamycin inhibit bacterial ribosome subunits

explain the oral contraceptives drug interaciton

clearance of contraceptions from the body

expalin the oral anticoagulants drug interaction

clindamycin inhibit bacterial ribosome subunits

Which classes of drugs inhibit bacterial ribosomal subunits?

tetracyclines & clindamycin

Which classes of antibiotics are known to accumulate in gingival crevicular fluid?

tetracyclines & metronidazole

what are tetracyclines & metronidazole used for and why

periodontal therapy bc of accumulation

what are tetracyclines & metronidazole adverese reactions (8)

anorexia,

nausea,

GI upset,

glossitis,

stomatitis,

xerostomia,

local irritation

and/or superinfection

what are tetracyclines & metronidazole drug interactions

oral contraceptives

What topical antibiotics were discussed in class?

neomycin: OTC, neosporin

mupircon: treats impetigo; infections with staphylococcus or streptococcus

what is neopmycin

OTC, neosporin

what is mupircon to treat

impetigo; infections with staphylococcus or streptococcus

What factors contribute to failure in anti-infective therapy? (6)

1. pt not adhering to schedule

2. wrong antibiotic prescribed

3. poor debridement

4. failure of antibiotic to reach target site

5. immunosupression

6. antibiotic resistance

What does Sulfonamide do and is?

inhibits DNA synthesis of bacteria

*FIRST ANTIBIOTIC*

Sulfonamide adverse reactions (7)

- allergic skin reactions

- nausea, vomiting, abdominal discomfort, headache & dizziness

- possible renal crystallization (drink plenty of water)