Antibiotics in O.S

ROLE OF ANTIBIOTICS

IN ORAL SURGERY

DEPARTMENT OF ORAL AND MAXILLO-FACIAL SURGERY

2

•Introduction• Factors determining the efficiency of antimicrobial agents•Classifications of antimicrobials agents • Principles of antibiotic therapy•Principles of antibiotic administrations•ß-lactam antibiotics•Erythromycin•Sulfonamides and Trimethoprim • Cotrimoxazole•Fluoroquinolones• Aminoglycosides• Metronidazole •Antiviral antibiotics • Antibiotic prophylaxis•Myths

CONTENTS

Introduction

3

• Antibiotic : An antibiotic is a substance produced by a

micro-organism, which selectively suppress the growth of or kill other micro-organism at very low concentrations.

• Chemotherapeutic agent: drug which is manufactured entirely by

chemical synthesis. Eg, sulphonamide, trimethoprim, & many

anti-tubercular drugs.

Tripati K.D, Essentials of Medical Pharmacology, 6th edition, Jaypee brothers, 2008. 4

Factors determining the efficiency of antimicrobial agents:

• Host defence

• Source of infection

• Tissues affected

• Margin of safety; &

• Bacterial susceptibility/resistance to the agent being used.

5Tripati K.D, Essentials of Medical Pharmacology, 6th edition, Jaypee brothers, 2008.

Classifications of antimicrobials agents:

On the basis of preparation

• Naturally occuring, eg, penicillins, cephalosporins, erythromycin, tetracycline,

chloramphenicol, & aminoglycosides.

• Synthetic, eg, sulfonamides


On the basis of family:• Penicillins• Cepholosporins• Sulfonamides• Tetracyclines• Aminoglycosides• Macrolide

On the basis of spectrum of activity:

• Narrow: penicillinG, erythromycin, streptomycin

• Broad spectrum: tetracycline, chloramphenicol

• Extended spectrum: amoxcycillin, ampicillin


On the basis of effect:

• Bacterostatic: erythromycin, tetracycline, sulfonamide, etc

• Bacterocidal: penicillins, cepholosporins, etc• Acting on gram +ve bacteria: penicilline,

cepholosporins, erythromycin, bactricin, tetracycline, gentamycin

• Acting on gram –ve bacteria: penicilline acts on gonococci


On the basis of systems:

• Urinary tract: nalidixic acid, furadantin• Skin: neomycin, bactricin, polymyxcin• Orally(locally): neomycin, streptomycin.


Principles of antibiotic therapyI Selection of antimicrobials:

• i) Clinical evaluation & diagnosis for antimicrobiological aetiology

• ii) Study of culture & sensitivity

• iii) Age of the patient

• iv) Pregnancy & neonatal

• v) Severity of disease10Tripati K.D, Essentials of Medical Pharmacology, 6th edition, Jaypee brothers, 2008.

• vi) Nature of the drug

• vii) Possibility of drug resistance

• viii) History of previous allergic reactions to a microbial agent

• ix) Risk of toxicity of the drug

• x) Cost of therapy

• xi) Narrow spectrum of antibiotic


II. Antimicrobial combinations• To have an additive synergistic effect against an organism.

• In mixed infections when bacteria are sensitive to different drugs.

• To achieve delay in development of resistance.

• To decrease the incidence of adverse reactions to an individual drug, another drug is added so that the doses of an individual drug can be reduced & possible toxic effects can be avoided.


• When infection is severe & body defence is inadequate & where the diagnosis is difficult

• To reduce the chances of super-infections

• To reduce the cost of therapy


The risk involved in combination therapy are following:

• Increased risk of super-infection by resistant organisms.

• Emergence of organisms resistant to multiple drugs used.

• Increased risk of adverse reactions.

• Sense of false security; which may lead to incomplete evaluation & inadequate therapy for the patient.

• Increase in the cost of therapy.

• In general, antibiotics should not be combined unless it is not documented by sensitivity testing & antagonism has been excluded. 14Tripati K.D, Essentials of Medical Pharmacology, 6th edition, Jaypee brothers, 2008.

III. Antimicrobial ProphylaxisThe situations where antibiotic prophylaxis is indicated are as

follows:

• For preventing endocarditis following minor surgical procedures or tooth extraction.

• In patients with compound musculoskeletal injury, penetrating wounds, skull injuries or rhinorrhea & otorrhoea.

• Deep punctured wounds that are at high risk of infections.

• Routine prophylaxis in cases of minor surgical procedures is not necessary.

15Oral and Maxillofacial Surgery by Neelima Malik Year 2001

Principles of antibiotic administrations

The principle comprise of the following:

• Dosage & duration of drug.

• Route & frequency of administration

16Oral and Maxillofacial Surgery by Neelima Malik Year 2001

ß-Lactam antibiotics:

General antibiotics of this group are: Penicillins Semisynthetic derivatives of pebicillin Cephalosporins.

• Structure


• Antibacterial activity: – inhibiting cell wall synthesis of suspectible

bacteria. They are effective mainly during growth phase when cell walls are being synthesized.

• Bacterial resistance– bacteria can produce enzymes known formerly, as

penicillinase. These enzymes can destroy the ß lactam ring in the nucleus of penicillins & its derivatives thereby rendering them ineffective.


Mechanisms of antibiotic resistance• 1. Production of enzymesdestroying and modifying AB

ß-lactamasesAG modifying enzymes

• 2. Decrease of cell membranepermeability

• 3. Active efflux of AB from cell

• 4. Modification of AB target sites


• Toxic effects: principle toxic effect is allergy

• Excretion: unchanged through kidney


Penicillins• Penicillin was first discovered

in 1929 by Fleming.

• It is derived from a mould, penicillin notatum.

• It was the first antibiotic to be used & is still the best.


Classification:Antibiotics Spectrum of activity

Natural penicillins (penicillin G,penicillin V)

All streptococci, minimal activityagainst staphylococci,meningococci, most G+ anaerobes

ß-lactamase resistant penicillins(nafcillin, methicillin, oxacillin,cloxacillin, dicloxacillin)

As above plus enhanced activityagainst staphylococci (exceptMRSA)

Extended-spectrum penicillins (ampicillin, amoxicillin, carbenicillin,ticarcillin, mezlocillin, piperacillin)

G+ cocci & some G- bacilli

ß-lactam with ß -lactamase inhibitor(amoxicillin/clavulanic acid, ampicillinsulbactam, ticarcillin/clavulanic acid,piperacillin/tazobactam)

Improved activity against ß-lactamase producing bacteria(staphylococci & selected G- bacilli)Not all ß-lactamses are inhibited

22

• Administrations

• Length of course

• Measurement of penicillins (units & micrograms): A standard method of expressing the potency of penicillin was adopted in 1944 using crystalline sodium penicillin G as the standard. It is expressed in 'International units'(iu). – 250 mg penicillin equals approximately 4,00,000 iu.


Toxic effects

Other effectsPregnancyLactationOral contraceptives


Cephalosporins

• Cephalosporins have similar structure to penicillin but have a different source.

• Compared with penicillins:– More resistant to– ß lactamase hydrolysis– Wider antibacterial spectrum– Improved PK-properties

• Mode of action: : They are bactericidal. They act by inhibiting the cell wall synthesis in growing bacteria.


Spectrum of activityAntibiotic Spectrum of activity

1. Generation . narrow spectrum(cephalexin, cephazolin, cephalotin,cephapirin)

G+ bacteria (= oxacillin) & some G-(E.coli, Klebsiella, Proteus)

2. Generation . extended spectrum(cefaclor, cefuroxime, cefoxitin)

G+ bacteria (= oxacillin) & improvedG- (Enetrobacteraciae, Citrobacter,Proteus)

3. Generation . broad spectrum(cefotaxime, ceftriaxone,ceftazidime, cefixime)

G+ bacteria (= oxacillin) & activityagainst wide range G- bacteria;Pseudomonas . CTZ

4. Generation . extended spectrum(cefepime, cefpirome)

G+ bacteria (= oxacillin) &marginally increased activityagainst G- bacteria + ESBL


First generation

Parenteral Oral

Cephalothin Cephalexin

Cefazolin Cephradine

Cefadroxil

Second generation

Parenteral Oral

Cefuroxime Cefaclor

Cefoxitin Cefuroxime axetil

Third generation

Parenteral Oral

Cefotaxim Cefixime

Ceftizoxime Cefpodoxime proxetil

Ceftriaxone Cefdinir

Ceftazidime Ceftibuten

Cefoperazone Ceftamet pivoxil

Fourth generation

Parenteral

Cefipine

Cefpirome


Adverse effects:• Pain : after im –severe with cephalothin• Thrombophelebitis of injected vein

• Diarrhoea – alteration of gut ecology

• Hypersensitivity reactions similar to pencillin

• Nephrotoxicity – highest with cephaloridine

• Broad sprectrum of activity ---– immunosuppression (candidasis)


Monobactams Aztreonam:

• Novel lactam in which other ring is missing

• Inhibits gm –ve enteric bacilli, but does not inhibit gm+ve cocci or faeceal aneorobes

• Indications: UTI, GIT

• Dose: 0.5-2g i.m, or i.v 6 hrly

• Azenam, Trezam 0.5, 1.0, 2.0 g/vial inj


Carbapenems Imipenem:

• Extermely potent & broad-spectrum ß lactam antibiotic• It is resistant to ß lactamases, inhibit pencillinase

producing staphylococci• Limiting feature is rapid hydrolysis by the enzyme

dehydropeptidase I located on the brush broder of renal tubular cells

• To overcome this clistatin is added• 0.5g i.v, 6 hrly • Indications: hospital acquired infections, cancer,

AIDS patients


Erythromycin • Principle member of Macrolide group of antibiotics.

• Broad spectrum antibiotic- static at low conc, % cidal at high conc.

• It is effective against most Gram-positive cocci, including many penicillin resistant strains of staphylococci and Staph. aureus, and many Gram-negative bacteria encountered in dental infection.


• Mode of Action: inhibition of protein synthesis.

• Absorption : upper small intestine, food delays. Hence, given 1 hr before food

• Excretion: unchanged in bile via liver, quarter of dose through kidney

• Toxic effects– Gastrointestinal effects– Cholestatic hepatitis– hypersensitivity


InteractionsAntihistaminics & sympathomemiticsTheophyllineCarbamazepineWarfarinBenziodiazepinesOral contraceptives

Pregnancy & lactation: safer drug

Concomitant use of other antibiotics:Lincomycin & clindamycin appear to compete with

erythromycin, hence these antibiotics should not be used along with erythromycin.


Newer macrolides• Limitations of erythromycin:

– narrow spectrum, – gastric intolerance, – gastric acid lability, – poor tissue penetration &– short ½ life

• Roxithromycin, Clarithromycin & Azithromycin•Uses: pharyngitis, tonsillitis, sinusitis, soft tissue infection


Sulfonamides

• Sulfonamides were first introduced in 1935.

• These agents are bacteriostatic; and get inactivated by presence of pus.

• Sulfonamides act by inhibition of bacterial synthesis of folic acid from Para-AminoBenzoic Acid (PABA).

• Absorption, Distribution and Excretion:


Toxic effects:

• Allergic reactions: skin rashes, polyartertitis nodsa,periphrea neuritis, photosensitivity

• Hemopoietic system: prolonged therapy lead to macrocytic anemia

• Renal damage: crystallization of sulfnomides lead to renal damage

• Pregnancy and Lactation: increase incidence of foetal malformation

• Oral Contraceptives: render ineffective of contraceptives36Tripati K.D, Essentials of Medical Pharmacology, 6th edition, Jaypee brothers, 2008.

Sulfadiazine • It penetrates blood-brain barrier and achieves high levels

in CSF.

• It is commonly used for prophylaxis to post-traumatic meningitis.

• A loading dose of 3 g is followed by 1 g, 6 hourly for 7 to 10 days.

37

• Caution should be exercised by taking a fluid intake of atleast 2 liters/day to avoid crystalluria and renal damage.

• Dose: 0.5g QID, to 2g TDS

Tripati K.D, Essentials of Medical Pharmacology, 6th edition, Jaypee brothers, 2008.

Cotrimoxazole

• This agent inhibits the conversion of folic to folinic acid which is important for bacterial synthesis of DNA and RNA.

• Spectrum of activity

• Indication:– acute exacerbation in post irradiation osteomyelitis

secondary to osteo-radio necrosis. – It is also used in mixed Actinomycotic infections along with

penicillin.


• Adverse reaction:nausea, vomiting, stomatitis, headache, rashesfolate deficiency, blood dyscrasias occur rarely

• Dosages: adult- 80mg trimitoprim+400mg sulfamethoxazole,2BD

children- 20 &100 mg respectively

• Septran, Sepmax, Bactrim,


Fluoroquinolones• Act by inhibiting DNA gyrase enzyme

• Antibacterial spectrum:– broad spectrum of activity– effective against staphylococci including methicillin

resistantStaph aureus (MRSA)– against streptococci including Strep pneumoniae. – Entero-bacteriaceae (E. coli, Klebsiella and Proteus

mirabilis), including many organisms which are resistant to penicillins, cephalosporins and aminoglycosides.


• Absorption, distribution and excretion: absorbed from GIT, distributed through body fluids & excreted by kidney

• Adverse reactions– G.I. tract toxicity– CNS toxicity

First generation Second generation

Norfloxacin Lomefloxacin

Ciprofloxacin Levofloxacin

Ofloxacin Saprofloxacin

Pefloxacin Gatifloxacin/ Moxifloxacin


Ciprofloxacin

• Most potent 1st generation

• Most suspectible ones are aerobic gm –ve bacilli

• Rapidly bactericidal activity & high potency

• Adverse effects: GI, CNS, Tendonitis & tendon rupture

• Contraindicated in pregnancy

• Uses: UTI, Gonnrrhoea, bone, soft tissue, wound infection, RTI

• Oral 250-750mg, i.v 100-200 42Tripati K.D, Essentials of Medical Pharmacology, 6th edition, Jaypee brothers, 2008.

Aminoglycosides• Used as stable salts which are highly water soluble • Not absorbed orally, distribute only extra-cellularly don't penetrate

brain or CSF

• Excreted unchanged in urine• Bactericidal and more active at alkaline pH

• Act by interfering bacterial protein synthesis• Active against aerobic gm –ve bacilli not anaerobes

• Narrow margin of safety• All exhibit ototoxicity & nephrotoxicity


Gentamycin

• Spectrum of activity: Gentamicin is effective against a wide range of Gram-positive and negative bacteria including penicillinase resistant staphylococci.

• Indications: severe anerobic infections, as prophylaxis in infective endocarditis

• Dose and administration: im/iv infusion• Adult dose is 3-7 mg/kg/day in 2-3 divided doses.• Child dose is 1-3 mg/kg/day in 2-3 divided doses.


• Toxic effects:– Ototoxicity– Nephro- toxicity

• Pregnancy and lactation: not safe drug


Metronidazole • It is a prototype nitromidazole.• It is effective in anaerobic infections and acute necrotizing

ulcerative gingivitis (ANUG).

• Metronidazole is used with one of the penicillin’s, usually, amoxycillin to treat acute orofacial infections with an anaerobic component of causative microorganisms.

• Metronidazole, can also be used in combination with

cephalosporins for treating anaerobic infections where there is penicillin allergy or any other contraindication.


• Administration, absorption and distribution: absorbed from GIT, distributed through body fluids, crosses placental barrier & appears in milk

• Excretion: urine, saliva, breast milk

• Toxic effects and contraindications: – Blood dyscrasias are reported. – CNS pathology

Metronidazole is contraindicated in patients who are taking phenytoin.

Enhance the effects of warfarin and prolong coagulation time.


LINCOMYCIN AND CLINDAMYCIN • Lincomycin was first described in 1963 and later its derivatives

clindamycin.

• Clindamycin is more active and has less side-effects.

• The oral preparations of clindamycin has replaced oral lincomycin.

• Lincomycin is reserved for parenteral administrations.


• Antibacterial activity: antibiotics are bacteriostatic; and act by inhibiting protein synthesis.

• Distribution: – well-distributed, – do not penetrate CSF, – appear in breast milk, – cross placental barrier, – distribution includes bone and because of their presence in

bone it has been suggested that these antibiotics are suitable for treating bone infections.

• These antibiotics form a second line of treatment in osteomyelitis.


• Administration & Excretion: absorbed orally, should be given 1 hr before meals. Excreted either through kidney or liver

• Toxic effects:– related to gastrointestinal tract– Hematological reactions include neutropenia, leucopenia,

agranulocytosis and thrombocytopenic purpura.– Pseudomembranous colitis is characterized by diarrhoea,

abdominal pain, fever, and blood and mucus faeces.

• Pregnancy and lactation: safe• 150-300mg QID oral, 200-600mg i.v, 8hrly.

• Dalcap , Clincin, Dalcin50Tripati K.D, Essentials of Medical Pharmacology, 6th edition, Jaypee brothers, 2008.

ANTIVIRAL ANTIBIOTICS Antiviral compounds can be classified as follows:• 1.Compounds interfering with nucleic acid synthesis/ Anti-

Herpes virus, e.g. idoxuridine, acyclovir.• 2.anti retro virus:

– a) nucleoside reverse transcriptase inhibitors: zidovudine, didanonsine,

– b) nonnucleaside reverse tanscriptase inhibitors: nevirapine, efavirenz

– c) protease inhibitors: ritonavir, indinavir• 3. anti-influnza virus: amantadine, rimantadine • 4.nonselective antiviral drugs: ribavirin, lamivudine


SUGGESTED ANTIBIOTIC THERAPY FOR MAXILLO-FACIAL TRAUMA PATIENT:

Wound Intra op iv Post op topical Post op enteral

Abrasions ---------- Bacitracin zinc(500U/g) bdPolymxin B (5000U/g)bdNeomycin sulfate (3.5mg/g) bd

-----------

Contusions & haematoma

--------- ------------------- Cephalexin Ad: 500mg 6hlyCh: 25-50mg/kg/d in 4 equal divided doses

Punctures ------------------- ----------------------- Pencillin V or Amoxicilin with clavulanic acidAd: : 500mg 6hlyCh: 15-50mg/kg/d in equally divided dose 6hly

Simple lacerations

--------------- Bacitracin zinc(500U/g) bdPolymxin B (5000U/g)bdNeomycin sulfate (3.5mg/g) bd

-----------------------

52Oral and Maxillofacial infection 4TH edition by Topazian.

Complex lacerations

Cefazolin Ad:0.5-1.5g/4hly-12hCh:25-50mg/kg/d in 4 equal divided doses

Bacitracin zinc(500U/g) bdPolymxin B (5000U/g)bdNeomycin sulfate (3.5mg/g) bd

Cephalexin Ad: 500mg 6hlyCh: 25-50mg/kg/d in 4 equal divided doses

Soft tissue avulsions




Burns Cefazolin Ad:0.5-1.5g/4hly-12hCh:25-50mg/kg/d in 4 equal divided doses




Maxillary/mandibular fractures

Aqueous pencillin G 2million unitsAqueous pencillin G 2million units for oral contaminants or cefazolinAd:0.5-1.5g/4hly-12hCh:25-50mg/kg/d in 4 equal divided doses, for cutaneous contaminants

---------------------------- Pencillin V, 500mgPencillin VAd: 500mg 6hlyCh:15-50mg/kg in equal divided doses 6hly

Craino-facial fractures


---------------------------------


Suspected intra cranial contamination

Nafcillin 2-6g 6hly, gentamicin 3-5mg/d in 3 equal divided doses (adults)

Bacitracin zinc(500U/g) bdPolymxin B (5000U/g)bdNeomycin sulfhate (3.5mg/g) bd



ANTIBIOTIC REGIMEN FOR OSTEOMYELITIS OF THE JAW:

REGIMEN I: for hospitalized/medically compromised patient or when intravenous therapy is indicated

• Aqueous pencillin, 2 million U iv 4hly, plus metronidazole 500mg, 6hly

• When improved for 48-72 hrs, switch to:Pencillin V, 500mg PO 4hly + metronidazole, 500mg

PO 6hly, for an additional 4-6 weeeksOR

• Ampicillin/ Sulbactam 1.5-3g iv 6hly• When improved for 48-72 hrs, switch to:• Amoxicillin /calvulanate (augmentin), 875/125mg PO bd,

for an additional 4-6 weeks 55Oral and Maxillofacial infection 4TH edition by Topazian.

REGIMEN II: for out patient procedure• Pencillin V, 2g, plus metronidazole, 0.5 g 8hly PO for 2-4

weeks after sequestrum removed & patient without symptoms

OR• Clindamycin, 600 to 900 mg 6hly iv, then:• Clindamycin, 300-450mg 6hly PO

OR• Cefoxitin(Mefoxin), 1 g 8hly iv or2g 4hly im or iv, no

symptoms, then switch to:• Cephalexin (Keflex), 500mg 6hly PO, for 2-4 weeks• For pencillin –allergic patients:• Clindamycin600 to 900 mg 6hly iv, then:• Clindamycin, 300-450mg 6hly PO, if allergy not of

anaphylactoid type 56Oral and Maxillofacial infection 4TH edition by Topazian.

ANTIBIOTIC THERAPY FOR ODONTOGEIC INFECTIONS:

• Pencillin remains emphrical antibiotic of choice in treatment of most dentoalveolar infection in the non-compromised host

• Metronidazole is an effective supplement to pencillin and enhances killing of anaerobes

• Oral clindamycin – both aerobic and anaerobic killing.

• If pencillin has been used for 2-3 days without resolution of infection then, use of another non- ß lactam or ß lactamase

stabile antibiotic ( ie clindamycin) should be considered.


Antibiotics are indicated in combination with surgery both therapeutic and prophylactically in the following situations:

– Acute cellulitis of dental origin.– Acute pericoronitis with elevated temperature and trismus– Deep fascial space infections– Open(compound) fractures of the mandible and maxilla or

other facial bones – Extensive, deep or old(>6hrs) orofacial lacerations – Dental infections or oral surgery in the compromised host– Prophylaxis for dental surgery in the patients with valvular

cardiac disease or a prosthetic valve


GUIDELINES FOR ANTIBIOTIC PROPHYLAXIS

Prophylaxis with antibiotics is indicated for:

• Procedures with an elevated contamination risk

• Patients who have risks related to internal illnesses (prophylaxis should be administered in cooperation with the attending physician)

• Patients with endocarditis risks, in whom antibiotics

prophylaxis is urgently necessary.[QI vol 38, no 8, 2007, 689-697] 59

Cardiac conditions associated with endocarditisProphylaxis recommended Prophylaxis not recommended

High risk Moderate risk Negligible risk

Prosthetic valves Most other congenital cardiac malformations

Isolated secondum atrial septal defect(ASD)

Previous bacterial endocarditis

Acquired valvular dysfunction

Surgical repair of ASD or PDA

Complex cyanotic congenital heart disease (CHD)

Hypertrophic cardiomyopathy

Previous coronary bypass graft surgery

Surgically constructed systemic pulmonary shunts

Mitral valve prolapse (MVP)

MVP without valvular regutation

Previous rheumatic fever

Cardiac pacemakers &implanted defibrillatorsInnocent heart murmurs


Dental procedures & endocarditis prophylaxis

Endocarditis prophylaxis recommended for

•Dental extraction

•Periodontal procedures including surgery, scaling & root planning

•RCT instrumentation or surgery beyond apex.

•Subgingival placement of antibiotic fibers or strips

•Intraligmentary local anaesthetic injections

Prophylatic cleaning of teeth or implants where bleeding is anticipated

Endocarditis prophylaxis not recommended for

•Restorative dentistry with/ without retraction cord

•LA injections (nonintraligamentary)

•Postoperative suture removal

•Taking impresions

•Taking oral radiograph

•Shedding of primary teeth

•Intracanal endodontic treatment, post placement & buildup.61Oral and Maxillofacial infection 4TH edition by Topazian.

Prophylactic regimens for dental procedures:

• Standard general prophylaxis: Amoxicillin

Adults 2.0gm, children 50mg/kg orally one

hour before procedure.

• Cannot oral medications: Ampicillin Adults 2.0gm, im/iv, children 50mg/kg im/iv within 30min

before procedure.


• Allergic to penicillin: ClindamycinAdults 500mg, children 20mg/kg orally one

hour before procedure. Or, Cephalexin/ Cephadroxil Adults 2.0gm, childern 50mg/kg

orally one hour before procedure. Or, Azithromycin/ Clarithromycin

Adults 500mg, children, 15mg/kg orally one hour before procedure.

• Allergic to penicillin & unable to take oral medications: Clindamycin – adults 600mg, children 15mg/kg iv

one hour before procedureOr Cephazolin—adults 1.0g, children 25mg/kg im/iv

within 30min before procedure. 63Oral and Maxillofacial infection 4TH edition by Topazian.

Prophylaxis in absence of active infection

• Short-term prophylaxis: begin 2-4 hrs before operation & continue to a maximum of 48 hrs after the operation (indicated in cases of unstable diabetes).

• Ultra short-term prophylaxis: begin 2-4 hrs before operation & continue to a maximum of 24 hrs after the operation (indicated in cases of endocarditis).

• One shot prophylaxis: a 1-time antibiotic parenteral administration (eg, at the beginning of the operation; indicated in trauma cases.)

[QI vol 38, no 8, 2007, 689-697] 64

CHOICE OF DRUGS Pregnancy: safer antibiotics are

• Pencillin G, • Ampicillin• Amox-clav• Cloxacillin• Pipercillin • Cephalosporins • Erythromycin

65

In breast feeding:

A. In milk is too small to be harmful to infant, safe in ordinary doses

Cephalosporins Cloxacillin Erythromycin Gentamycin Pipercilin

Tripati K.D, Essentials of Medical Pharmacology, 6th edition, Jaypee brothers, 2008.

66

B. With special precautions or drugs contraindicatedAminoglycosides:-- risk is not known, but manufactures advise caution

Amoxycillin/ampicillin:- diarrhoea, candidasis

Azithromycin:- avoid, no, risk to infant

Cotrimoxazole :- folate deficiency,risk of kernicterus, haemolysis in G-6-PD deficient; safe for healthy older infants

Clindamycin:- small amount in milk, risk of diarrhoea, watch for blood in stools

Ciprofloxicin:- high conc in milk, theoretical risk of arthropathy

Metronidazole:- significant amount in milk, avoid high doses, suspend breast feeding for 12hr after single use

Penincillins:- toxicity unlikely but risk of allergy

Streptomycin:- compatible with breast feeding, watch for diarrhoea & thrush in infantSulfonamides:- rashes, small risk of kernicterus in neonate, haemolysis in G-6-PD deficient, safer for older infants

Tetracyclines:- growth retardation, candidasis, tooth discoluration

Myths

• Myth# 1 : antibiotics are not harmful

67Swifth J Q, Antibiotic therapy- managing odontogenic infections. The Dental Clinics of North America 46(2002) 623-633.

• Myth# 2: doses & duration of antibiotic treatment should be nonspecific & variable for most odontogenic infections.

• A rule of thumb when prescribing is that “the antibiotic should last for 3 days after the patient’s symptoms have resolved”.


• Myth#3 antibiotics are always indicated when treating dental pain

• Myth#4 Clindamycin is a first line drug for infections


•Myth#5 If a peri-apical radiolucency, sinus tract, fistula, or localised abscess is present, antibiotics are always indicated

•Myth#6 Antibiotics must be implemented several days before commencement of surgery


• Myth#7 Indurated soft tissues means drainage is not indicated

• Myth#8 Over prescription of antibiotic therapy does not occur in dentistry


BIBLIOGRAPHY• Oral and Maxillofacial infection 4TH edition by Topazian.• Oral and Maxillofacial Surgery by Neelima Malik Year 2001• Oral and Maxillofacial Surgery by B.Srinivisan 2nd Edition• Pharmacology by K.D. Tripati 5th edition• Pharmacology & pharmacotherapeutics by Sathoskar 6th edition. • Swifth J Q, Antibiotic therapy- managing odontogenic infections. the

dental clinics of north america 46(2002) 623-633.• Seymour r & whitworth, Antibiotic prophylaxis for endocarditis, prosthetic

joints & surgery. The Dental clinics of North America 46(2002) 635-651.• Hersh E, Antibiotics & oral contraceptives. The Dental clinics of North

America 46(2002) 653-664.• Lambrecht T, Antibiotics prophylaxis and therapy in oral surgery: a review,

QI, vol 38, no.8, sep 2007, 689-697. • Tripati K.D, Essentials of Medical Pharmacology, 6th edition, Jaypee

brothers, 2008. 72

73

Classification

Fourth generation

Similar to 3rd gen. but highly resistant to ß lactamases

Third generation:

less activity against Gram-positive organisms than first generations and more activity against Entero-bacteriaceae, including beta-lactamase producing strains.

Second generation:

greater activity against Gram- positive microorganisms to first generation cephalosporins.

includes cefotaxime

First generation: effective against Gram-positive microorganisms, except enterococci.

Methicillin resistant Staph. aureus and Staph. epidermidis-

They are also active against E.coli, Klebsiella, Pneumonia and P mirabilis.

includes cephalothin and cephalexin.

74

Documents

Antibiotics in O.S