Unit IV: Antibiotics
What are procedures that DO NOT require premedication?
-block injections -radiographs -impressions -sealant placement -fluoride treatment -any procedure NOT producing much bleeding
What is the dosing for cephalexin?
adult: 2.0g child: 50mg/kg
What are the D/DIs of metronidazole?
DO NOT take with alcohol, even mouthiness
What are the drugs in the ampicillin group?
amoxicillin, ampicillin
What do bactericidal antibiotics do?
kill bacteria
What does spectrum mean?
range of activity of a drug; can be narrow, intermediate, or broad
What are some dental-specific characteristics of tetracycline?
-accumulates in dentin and enamel of unerupted teeth -concentrates in gingival crevicular fluid -doxycycline and minocycline are useful against A. a infections in LAP and refractory perio
What are the ADEs of penicillin?
-allergic reactions more common than any other antibiotic drug group (pt. with history of ANY allergies are more likely to be allergic to penicillins) -pseudomembranous colitis -GI upset
What are the antibiotics approved for prophylactic use?
-amoxicillin -clindamycin -cephalexin -azithromycin/clarithromycin
What are the unique periodontal properties of metronidazole?
-anti-inflammatory effects -has the ability to concentrate in the gingival sulcus
What are two special features of tetracyclines that make them especially suited for periodontal?
-anticollagenase properties (collagenase breaks down collagen, appears with inflammation) -high substantivity: concentrates in gingival crevicular fluid at 2-4x blood levels following multiple doses
How can antibiotics cause allergic reactions?
-anything from mild rash to full blown fatal systemic anaphylaxis -cross-allergenicity -penicillin and cephalosporins are cross-allergenic
Which high-risk cardiac conditions is IE chemoprophylaxis indicated for?
-artificial heart valves -a history of infective endocarditis, certain specific serious congenital heart conditions including un- or completely repaired cyanotic congenital heart disease, including those with palliative shunts and conduits, a completely repaired congenital heart defect with prosthetic material or device (whether replaced by surgery or catheter placement, during the first 6 months after placement), any repaired congenital defect with residual defect at the site or adjacent to the site of a prosthetic patch or a prosthetic device -a cardiac transplant that develops a problem in a heart valve
What are conditions that usually DO NOT require premedication?
-breast implant -heart stents -splenectomy
What are unique periodontal properties of tetracyclines?
-concentrate in the gingival crevicular fluid -anti-collagenase properties
How does azithromycin treat periodontal disease?
-concentrates in phagocytes and macrophages -exhibits a post-antibiotic effect (longer effect) -anti-inflammatory effects
What are the D/DIs of tetracyclines?
-dairy products (minoclycline, doxycycline ok) -antacids and iron-containing products
What is the protocol for IE chemoprophylaxis?
-during select dental procedure -for patients with specific and high-risk cardiac conditions -adhering to specific antibiotic regimens
What are other (unusual) conditions that may or may not require premedication?
-hemophilia -renal transplant/advanced renal disease (dialysis) -heart shunts -immunosuppression (cancer/chemo; organ transplant) -SLE -history of IV drug use
What are the advantages ampicillins provide over Pen VK in the treatment of dental infections?
-improved spectrum (are not broad spectrum) -are not inactivated by the presence of stomach acid (can take with food) -offer tid dosing over qid dosing (more convenient for pt)
What are the major penicillin groups?
-natural penicillins -ampicillins -beta-lactamase inhibitors -penicillinase-resistant penicillins -extended spectrum penicillins
What are the D/DIs of antibiotics?
-oral contraceptives (estrogen needs bacteria in the gut to break it down before it reabsorbs to its active form) -oral anticoagulants (reduce vitamin K-producing normal flora within the gut) -other anti-infective agents (bacteriostatic and bactericidal agents do not work well together)
What are possible reasons for failure of antibiotic therapy?
-patient compliance -ineffective antibiotic -poor debridement -resistant organism -concentration did not reach the site of infection -host defenses are inadequate
What are the unique periodontal properties of azithromycin?
-post-antibiotic effect -concentrates in phagocytes and macrophages -anti-inflammatory
What are the clinical considerations regarding antibiotic resistance?
-prescribe antibiotics only when absolutely necessary -prescribe only one antibiotic; add a second only if clearly necessary -educate patient on correct use of antibiotics, including taking exactly as prescribed -educate patient on correct dosage, instructions for use, completing therapy even if patient feels better -advise patient on adverse effects, including potential for resistance if misused -educate patient on children's dose forms, liquid and chewable, may contain sugar as a sweetening agent
What are the ADEs of antibiotics?
-superinfection/normal flora disruptions -GI effects (nausea, vomiting, diarrhea) -allergic reactions -photosensitivity
What are factors to consider when using premedication (prophylactic antibiotics)?
-the specific dental procedure -the cardiac and medical condition of the patient -the drug and dose
When are antibiotics indicated in the dental setting?
-therapeutically for odontogenic infection, endodontic indications, implant indications, and/or periodontal indications -prophylactically for infective endocarditis/prosthetic joint infection
What are the ADEs of tetracyclines?
-tooth discoloration (yellow-gray fluorescent discoloration) -yellow-brown discoloration of tongue -photosensitivity
What are the clinical considerations in antibiotic therapy?
-we must establish a clear indication for anti-infective therapy, determine the patient's health status, and select the appropriate antibiotic -prescribe only when necessary, narrowest spectrum, lowest toxicity for suspected population -medical consult may be required -educate the patient! -regarding how to take the antibiotic: until it's gone, on time as much as possible, on an empty stomach and with full glass of water, avoid dairy if applicable -potential for allergic reaction, GI complaints, photosensitivity, superinfection/pseudomembranous colitis -interference with oral contraceptives -children's dose forms, liquid and chewable, may contain sugar as a sweetening agent
What is the dosing for doxycycline hyclate (Periostat)
20mg by mouth twice a day (ideally, spaced 12 hours apart) for no less than 3 months and up to 9 months
What are the natural penicillins?
Pen G and Pen V
What is the dosing for amoxicillin?
adult: 2.0g child: 50mg/kg
What is the dosing for azithromycin/clarithromycin?
adult: 500mg child: 15mg/kg
What is the dosing for clindamycin?
adult: 600mg child: 20mg/kg
Which dental procedures is IE chemoprophylaxis indicated for?
all dental procedures that involve manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa
What is the drug of choice for infective endocarditis?
amoxicillin
What can decrease the absorption of macrolides?
antacids
What are antibiotic agents?
antibacterial agents produced by microorganisms
Which bacteriostatic macrolide agent is specially suited for periodontal therapy?
azithromycin
What are some examples of macrolides?
azithromycin (Zithromax, Z-Pak), clarithromycin, erythromycin (Ery-Tab, E-Mycin)
Why are penicillinase-producing staphylococci resistant?
because their enzymes destroy some penicillins by breaking apart the beta-lactam ring
What does the structure of penicillins include?
beta-lactam ring (when broken, penicillin becomes inactivated)
What are the ADEs of metronidazole?
black hairy tongue and metallic dysgeusia
What does infection mean?
both an invasion of the body by pathogenic microorganisms and the reactions the tissues to their presence
What is the spectrum of metronidazole?
broad
What is the spectrum of cephalosporins?
broad (but expensive)
What is the spectrum of ciprofloxacin?
broad (can lead to superinfection)
What is the spectrum of clindamycin?
broad, but also very active against several anaerobes
What is the spectrum of tetracycline?
broad, long duration of action due to enterohepatic cycling
What are doxycycline hyclate (Periostat) tablets used for?
can be used as an adjunct to scaling and root planing to promote attachment level gain and reduce pocket depth in patients with adult periodontitis
How is infective endocarditis caused?
caused by an infection of the heart valves or endocardium with an organism
What are some examples of cephalosporins?
cephalexin (Keflex), cefadroxil (Duricef)
Which antibiotics were historically the premedication drug of choice against PJI?
cephalosporins
Which type of antibiotics are structurally similar to and cross-allergenic with penicillins?
cephalosporins
How is the production of penicillinase by some bacteria dealt with?
clavulonic acid is added to amoxicillin to produce Augmentin
How can dairy products affect ciprofloxacin?
delay absorption
What are the newest (2014) guidelines for PJI premedication?
do not recommend prophylaxis for patients "with pins, plates, and screws, or for those who have undergone total joint replacement" except for a very few
What does broad spectrum mean?
effective against many different pathogens
What does narrow spectrum mean?
effective against some gram-positive pathogens
T/F: If an organism is penicillin sensitive, Pen G will be less effective.
false (will be MORE effective)
What are the D/DIs of penicillins?
food increases breakdown of penicillin in the stomach
When are extended spectrum penicillins used?
for parenteral use against systemic infections (uncommon in dentistry and require medical treatment)
How can metronidazole treat periodontal disease?
has anti-inflammatory effects and has the ability to concentrate in the crevicular fluid
When should you not use cephalosporins for prophylactic use?
if patient has shown anaphylaxis, angioedema, or urticaria with penicillins
When should tetracyclines be avoided?
in last half of pregnancy and up to 8-9 years old
What does superinfection/suprainfection mean?
infection caused by the proliferation of microorganisms different from those causing the original infection
What is pseudomembranous colitis?
inflammation of the large intestine due to an overgrowth of Clostridium dificile
What do bacteriostatic antibiotics do?
inhibit growth/multiplication/metabolic processes of bacteria (think of it as injuring but not killing)
What does clavulanate do?
inhibits bacterial penicillinase effectiveness, allowing amoxicillin to be effective against a bacteria despite the bacteria's ability to produce penicillinase
What does it mean if you see "-cillin" at the end of a drug name?
it is probably a penicillin
What does it mean if you see the root "sulf" in a drug name?
it is probably a sulfonamide antibiotic
What does the anaerobic spectrum of metronidazole mean?
it is specifically good against most obligate anaerobes
What does "-cef-" or "-ceph" in the name of a drug suggest?
may be a cephalosporin
When are antibiotics used for implant indications?
may give systemic plus antimicrobial rinse following placement, peri-implantitis may indicate systemics
What are the antibiotic agents uniquely suited for periodontal use?
metronidazole, tetracyclines, doxycycline hyclate tablets, azithromycin
What organisms cause bacterial endocarditis?
most commonly S. viridans, an a-hemolytic streptococcus
When is Pen V used?
most often used in dentistry, but offers only a narrow spectrum of activity
When is Pen G used?
mostly used IV and is not often used in dentistry
What are the old (2003) guidelines for PJI premedication?
premed in first 2 years following surgical placement of prosthetic joint
What are the ADEs of clindamycin?
pseudomembranous colitis (BIGGIE!)
What are the newer (2006) guidelines for PJI premedication?
recommend premed for life
When are penicillinase-resistant penicillins used?
reserved for use against only penicillinase-producing organisms, including staphylococci
What does resistance mean?
resistance (related to antibiotics) is the natural or acquired ability of an organism to be immune to or not susceptible to the effects of an anti-infective agent
What does the suffix "-cycline" mean?
should trigger you to identify it as a tetracycline
What is the prophylactic regimen for premedication?
single "knock-out" (high) dose 30-60 minutes prior to dental procedure
What are the unique periodontal properties of doxycycline hyclate tablets?
subantimicrobial dose is immunomodulatory (suppresses host response to bacteria)
What are antibacterial agents?
substances that destroy or suppress the growth or multiplication of bacteria
What are antifungal agents?
substances that destroy or suppress the growth or multiplication of fungi
What are antiviral agents?
substances that destroy or suppress the growth or multiplication of viruses
What are anti-infective agents?
substances that inhibit/kill organisms that cause infections
What are the miscellaneous other antibiotics for non-dental use?
sulfonamides (first antibiotics), sulfamethoxazole-trimethoprim (Bactrim), nitrofurantoin (Macrobid)
When are antibiotics are used for periodontal indications?
systemics may be used in aggressive perio, topicals (local anti-infectives) may be used in localized chronic perio
What are some examples of tetracycline?
tetracycline, doxycycline, minocycline
What are the antibiotics that can cause photosensitivity?
tetracyclines, ciprofloxacin, and sulfonamides
T/F: Probiotics may prevent superinfection and normal flora disruptions for the patient taking antibiotics.
true
T/F: The amount of resistance a bacteria displays to an antibiotic is proportional to the clinical use of the antibiotic.
true
What are the symptoms of pseudomembranous colitis?
watery (sometimes bloody) diarrhea, often with abdominal cramping
When can infective endocarditis occur?
when bacteria is introduced to the blood stream (bacteremia) by dental procedures or other event
What does it mean if a drug name contains "-mycin?"
you should think macrolide antibiotic (clindamycin is the exception)
