Antibiotics in Dentistry

KMCT DENTAL COLLEGE Manassery, Mukkam

ANTIBIOTICS IN

DENTISTRY

Presented By:

Niyas Ummer 1st Year PG Department of Oral Medicine and Radiology

KMCT DENTAL COLLEGE ORAL MEDICINE AND R ADIOLOGY

Overview • • • • •

Introduction Terminology History Classification General Considerations o Routes of administration o Choice of agent o Combined use o Problems with use o Prophylactic use o Failure

•

Commonly used antibiotics in dentistry o Mechanism of action o Uses o Adverse Effects o Interactions o Contra-indications o Dosage and availability

•

Recent Advances Misuse Conclusion References

• • •


Introduction to Antibiotics The magic word ‘Antibiotic’ inevitably springs to mind whenever an infection has to be dealt with. Antimicrobial drugs are the greatest contribution to 20th century of therapeutics - ‘Antibiotic era’. Their advent changed the outlook of the physician about the power drugs can have on diseases. Antibiotics are essential weapon against infection; hence wise use of antibiotics requires the clinician to take the stance that positive indication must be present before antibiotic drugs are prescribed. As a class, antibiotics are one of the most frequently used as well as misused drugs.

Terminologies Used Antibiotics: Substances produced by microorganisms, which selectively suppress the growth of or kill other microorganisms at very low concentrations. The term "antibacterial" is derived from Greek anti - "against” and baktēria, "staff, cane". The term "antibiotic" derived from anti and bios, "life". Chemotherapy: Treatment of systemic infections with specific drugs that selectively suppress the infecting microorganism without significantly affecting the host Antimicrobial Agent: Synthetic as well as naturally obtained drugs that attenuate microorganisms

History of Antibiotics Milestones in History 

 

 

Louis Pasteur observed, "if we could intervene in the antagonism observed between some bacteria, it would offer perhaps the greatest hopes for therapeutics“ Term 'antibiosis‘ coined by the French bacteriologist Jean Paul Vuillemin Antibiosis first described in 1877 in bacteria when Louis Pasteur and Robert Koch observed that an airborne bacillus could inhibit the growth of Bacillus anthracis Renamed ‘antibiotics’ by Selman Waksman, an American microbiologist, in 1942 Synthetic antibiotic chemotherapy began in Germany with Paul Ehrlich in the late 1880s

In 1928, Alexander Fleming observed antibiosis against bacteria by a fungus of the genus Penicillium. He postulated the effect was mediated by an antibacterial compound named penicillin, and that its antibacterial properties could be exploited. He attempted to use a crude preparation to treat some infections, but unable to pursue its further development.


Period of Empirical Use (16th - 17th Century)     

Mouldy curd by Chinese on boils Chaulmoogra oil by Hindus in leprosy Chenopodium by Aztecs for intestinal worms Mercury by Paracelsus for syphilis Cinchona bark for fevers

Chenopodium

Chaulmoogra

Phase of Dyes and Organometallic Compounds Paul Ehrlich (1890-1935) coined the term ‘chemotherapy’. He developed two antibiotics, atoxyl for sleeping sickness and arsphenamine for syphilis. Paul Ehrlich

Modern Era of Antibiotics Domagk (1935) developed Prontosil for use in pyogenic infections. It came to be known as the first commercially available antibiotic.

Prontosil

Domagk


Classification of Antibiotics Based on Chemical Structure: Sulfonamides

Sulfadiazine, Sulfones (Dapsone)

Diaminopyridines

Trimethoprim, Pyrimethamine

Quinolones

Nalidixic Acid, Norfloxacin, Ciprofloxacin

β-lactam

Penicillins, Cephalosporins, Monobactams, Carbapenems

Tetracyclines

Oxytetracycline, Doxycycline

Nitrobenzene derivative

Chloramphenicol

Aminoglycosides

Streptomycin, Gentamycin, Amikacin, Neomycin

Macrolide

Erythromycin, Clanthromycin, Azithromycin

Lincosamide

Lincomycin, Clindamycin

Glycopeptide

Vancomycin, Teicoplanin

Oxazolidinone

Linezolid

Polypeptide

Polymyxin-B, Colistin, Bacitracin, Tyrothricin

Nitrofuran derivatives

Nitrofurantoin, Furazolidone

Nitroimidazoles

Metronidazole, Tinidazole

Nicotinic acid derivatives

Isoniazid, Pyrazinamide, Ethionamide

Polyene

Nystatin, Amphotericin-B, Hamycin

Azote derivatives

Miconazole, Clotrimazole, Ketoconazole, Fluconazole

Others

Rifampin, Spectinomycin, Sodium fusidate, Cycloserine, Viomycin, Ethambutol, Thiacetazone, Clofazimine, Griseofulvin

Based on type of organisms against which primarily active: Antibacterial

Penicillins, Aminoglycosides, Erythromycin, etc.

Antifungal

Griseofulvin, Amphotericin B, Ketoconazole, etc.

Antiviral

Acyclovir, Amantadine, Zidovudine, etc.

Antiprotozoal

Chloroquine, Pyrimethamine, Metronidazole, Diloxanide, etc.

Anthelmintic

Mebendazole, Pyrantel, Niclosamide, Diethyl carbamazine, etc.


Based on spectrum of activity: Narrow-spectrum

Penicillin G, Streptomycin, Erythromycin

Broad-spectrum

Tetracyclines, Chloramphenicol

Based on type of action: Primarily bacteriostatic

Sulfonamides, Erythromycin, Tetracyclines, Ethambutol, Chloramphenicol, Clindamycin, Linezolid

Primarily bactericidal

Penicillins, Cephalosporins, Aminoglycosides, Vancomycin, Polypeptides, Nalidixic acid, Rifampin, Ciprofloxacin, Isoniazid, Metronidazole, Pyrazinamide, Cotrimoxazole

Based on source obtained from: Fungi

Penicillin, Cephalosporin, Griseofulvin

Bacteria

Polymyxin B, Colistin, Bacitracin, Tyrothricin, Aztreonam

Actinomycetes

Aminoglycosides, Tetracyclines, Chloramphenicol, Macrolides, Polyenes

Choice of an Antibiotic Agent Choosing the right antibiotic depends on qualities of patient, the infecting organism and the drug, as given below. Patient Factors a) Age: o

The age of the patient affects kinetics of drugs, including its absorption, metabolism and excretion.

b) Genetic Factors: o

Primaquine, nitrofurantoin, sulfonamides, chloramphenicol and fluoroquinolones produce haemolysis in Glucose-6-Phosphate Dehydrogenase deficient patient

c) Renal and Hepatic Function: o

Cautious use and dose modification advised when the organ for disposal of the drug is defective/diseased


Renal Failure Dose reduction in mild failure

Aminoglycosides, Amphotericin B, Cephalosporins, Ethambutol, Vancomycin, Flucytosine

Dose reduction in moderate-severe failure

Metronidazole, Carbenicillin, Cotrimoxazole, Aztreonam, Meropenem, Fluoroquinolones, Clarithromycin, Imipenem

Drugs to be avoided

Cephalothin, Talampicillin, Nalidixic acid, Tetracyclines, Nitrofurantoin (except doxycycline)

Liver Disease Dose reduction

Chloramphenicol, Isoniazid, Metronidazole, Rifampin, Clindamycin

Drugs to be avoided

Erythromycin estolate, Tetracyclines, Pyrazinamide, Nalidixic acid, Talampicillin, Pefloxacin

d) Local Factors: o

o o o

o

o o

Pus and secretions decrease the efficacy of sulfonamides and aminoglycosides Necrotic material or foreign body makes eradication impossible Haematomas foster bacterial growth Lowering of pH at the site of infection reduces activity of macrolides and aminoglycosides Anaerobic environment in the centre of an abscess impairs bacterial transport processes which concentrate aminoglycosides in the cell Penetration barriers hamper the access to the site of infection Some drugs like trimethoprim and fluoroquinolones attain high concentration due to ion trapping

e) Drug Allergy: o

o

If a drug has caused allergic reaction, it has to be avoided in that patient. β-lactams, sulfonamides, fluoroquinolones, nitrofurantoin frequently cause allergy.

f) Impaired Host Defense: o o

o

Pyogenic infections are common in neutropenic patients. Infections by low grade pathogens and intracellular organisms occur if cell-mediated immunity is impaired. In a patient with normal host defense, a bacteriostatic AMA may achieve cure.


o

But in an impaired host defense, intensive therapy with cidal drugs is recommended.

g) Pregnancy: a. All AMAs should be avoided in the pregnant because of risk to the foetus b. Penicillins, many cephalosporins and erythromycin - safe c. Tetracyclines - acute yellow atrophy of liver, pancreatitis and kidney damage in the mother - teeth and bone deformities in the offspring d. Aminoglycosides - foetal ear damage Risk Category of Drugs in Pregnancy Category

Description

A

Adequate studies in pregnant women have failed to demonstrate a risk to the foetus

B

Adequate human studies are lacking, but animal studies have failed to demonstrate a risk to the foetus amoxicillin or, Adequate studies in pregnant women have failed to demonstrate a risk to the foetus, but animal studies have shown an adverse effect on the foetus

C

No adequate studies in pregnant women and animal studies are lacking or have shown an adverse effect on foetus, but potential benefit may warrant use of the drug in pregnant women despite potential risk

D

There is evidence of human foetal risk , but the potential benefits from use of the drug may be acceptable despite the potential risk

X

Studies in animals or humans have demonstrated foetal abnormalities, and potential risk clearly outweighs possible benefit

Organism-related Factors a) Initial Empirical Therapy: Identification of the microorganism and antimicrobial sensitivity testing are time consuming, expensive & impractical. Sometimes, it i s not possible to obtain appropriate samples of infected material. Furthermore, well defined site and features of the infection enable organisms causing such infections t o be reliably deduced. SO empirical therapy is usually carried out. In addition, most dental infections are acute in nature, hence treatment cannot be delayed. b) Identification of Causative Organism: Type of bacteria (aerobic/anaerobic) and their specific identification is necessary for proper management of the condition. Most odontogenic infections (70%) are caused by a mixture of aerobic and anaerobic bacteria. Well-circumscribed chronic non-advancing abscesses contain mostly anaerobic bacteria. Cellulitis type of


lesions show exclusively aerobic bacteria. When the infection is contained longer & controlled, only anaerobic flora is evident. Abscesses may contain anaerobic bacteria. c) Antibiotic Sensitivity for Causative Organism: Antibiotic therapy is initial / empirical or definitive, depending on whether the organism is identified precisely.

Drug Factors a) Spectrum of Activity: For definitive therapy, a narrow-spectrum drug which selectively affects the concerned organism is preferred. For empirical therapy, often a broad-spectrum drug has to be used to cover all likely pathogens. b) Type of Activity: Acute infections resolve faster with a cidal drug and reduces the number of bacteria at the site of infection. For patients with impaired host defence, lifethreatening infections, infections at less accessible sites (SABE) or when carrier state is possible (typhoid), a bactericidal drug is preferred. c) Sensitivity of the Organism: On the basis of MIC values (if available) and consideration of postantibiotic effect d) Relative Toxicity: Less toxic antibiotic is preferred e) Pharmacokinetic Profile: Antibiotic has to be present at the site of infection in sufficient concentration for an adequate length of time. Aminoglycosides and fluoroquinolones produce ‘concentration-dependent inhibition’, where the inhibitory effect depends on the ratio of peak concentration to the MIC. β-lactams, glycopeptides and macrolides produce ‘time-dependent inhibition’ where the antimicrobial action depends on the length of time the concentration remains above MIC. Drug which penetrates better and attains higher concentration at the site of infection is more effective. f) Route of Administration: Less severe infections warrant the use of oral antibiotic. Serious infections require parenteral antibiotics. g) Evidence of Clinical Efficacy: Relative value of different AMAs in treating an infection is decided on the basis of comparative clinical trials. Optimum dosage regimens and duration of treatment are also determined on the basis of such trials. Reliable clinical trial data, if available, is the final guide for choice of the antibiotic.


h) Cost: Less expensive drugs are to be preferred

Principles of Antibiotic Dosing for Orofacial Infections       

Employ high doses for a short duration Achieve blood levels of antibiotic at 2-8 times the MIC Use frequent dosing intervals Determine the duration of therapy by remission of disease Proper time intervals (four times the T½) Proper route of administration Penetration of drug

Routes of Administration

Antibiotic Combinations More than one AMAs are frequently used concurrently to treat infections. Objectives: i. ii. iii. iv. v.

To achieve synergism and enhance antimicrobial action To reduce severity or incidence of adverse effects To prevent emergence of resistance To broaden the spectrum of antimicrobial action for polymicrobial infections For empirical therapy of an infection in which the cause is unknown

Prophylactic Use Antibiotic prophylaxis with dental procedures is reasonable only for patients with cardiac conditions associated with the highest risk of adverse outcomes from endocarditis.


High Risk Patients:  Prosthetic cardiac valve or prosthetic material used in valve repair  Previous endocarditis  Congenital heart disease only in the following categories:  Unrepaired cyanotic congenital heart disease, including those with palliative

shunts and conduits  Completely repaired congenital heart disease with prosthetic material or device, whether placed by surgery or catheter intervention, during the first six months after the procedure  Repaired congenital heart disease with residual defects at t he site or adjacent to the site of a prosthetic patch or prosthetic device  Cardiac transplantation recipients with cardiac valvular disease Dental procedures for which prophylaxis is reasonable: All dental procedures that involve manipulation of gingival tissue or the periapical region of teeth, or perforation of the oral mucosa.

Antibiotic prophylaxis is NOT recommended for:       

Routine anesthetic injections through noninfected tissue Taking dental radiographs Placement of removable prosthodontic or orthodontic appliances Adjustment of orthodontic appliances Placement of orthodontic brackets Shedding of deciduous teeth Bleeding from trauma to the lips or oral mucosa


Problems associated with Antibiotic use 1. Toxicity a) Local Irritancy: 

Toxicity that is exerted at the site of administration. Gastric irritation, pain and abscess formation are evident. Complication of IV administration that commonly arises is thrombophlebitis of the injected vein. E.g. erythromycin, tetracycline, chloramphenicol

b) Systemic Toxicity: 

Dose related and predictable organ toxicities can also occur.

High Therapeutic Index

Penicillins, some Cephalosporins, Erythromycin

Low Therapeutic Index

Aminoglycosides, Tetracyclines, Chloramphenicol

Very Low Therapeutic Index

Polymyxin B, Vancomycin, Amphotericin B

2. Hypersensitivity Reactions that range from rashes to anaphylactic shock, that are unpredictable and unrelated to dose. Practically all AMAs are capable of causing hypersensitivity. More common culprits include penicillins, cephalosporins, sulfonamides, fluoroquinolones. 3. Drug Resistance It is the unresponsiveness of a microorganism to an AMA. It can be of the following types: Natural Resistance: Microorganisms inherently lack the metabolic process or the t arget site which is affected by the particular drug. It is generally a group or species characteristic. Acquired Resistance: Development of resistance by an organism (which was sensitive before) due to the use of an AMA over a period of time. It occurs by mutation or gene transfer. Cross Resistance: Acquisition of resistance to one AMA conferring resistance to another AMA, to which the organism has not been exposed. It may be complete, or partial; twoway, or one-way. Prevention:  No indiscriminate and inadequate or unduly prolonged use – prefer symptom

determined shorter courses  Prefer rapidly acting and selective (narrow spectrum) AMAs


 Broad-spectrum drugs - only when a specific one cannot be determined or is

not suitable  Use combination of AMAs for prolonged therapy  Infection by organisms notorious for developing resistance treated intensively 4. Superinfection Appearance of a new infection as a result of antimicrobial therapy. It is commonly associated with the use of broad/extended-spectrum antibiotics. It is more common when the host defense is compromised. Sites involved are those that normally harbor commensals. They are generally more difficult to treat. To minimize superinfections:  Use specific (narrow-spectrum) AMA  Do not use antimicrobials to treat trivial, selflimiting or untreatable (viral)

infections  Do not unnecessarily prolong antimicrobial therapy 5. Nutritional Deficiencies Some of the B complex group of vitamins and Vitamin K are s ynthesized by the intestinal flora. Prolonged use of antimicrobials which alter this flora result in vitamin deficiencies. 6. Masking of an infection Short course of an AMA may be sufficient to treat one infection but only briefly suppress another one contacted concurrently. Other infection will be masked initially, but will manifest later in a severe form.

Failure of Antibiotic Therapy Success of therapy measured either clinically in terms of improvement in symptoms/signs or microbiologically as eradication of the infecting or ganism. Antimicrobials may fail to cure an infection/fever, or there may be relapses. When a real or apparent failure of the antimicrobial regimen occurs, the diagnosis and therapy should be reviewed. Causes of failure: i. Improper selection of drug, dose, route or duration ii. Treatment begun too late iii. Failure to take necessary adjuvant measures iv. Poor host defense v. Infecting organism present behind barriers vi. Trying to treat untreatable infections or other causes of fever vii. Presence of dormant or altered organisms which later give rise to a relapse


Common Antibiotics in Dentistry 1. PENICILLINS

Classification: Natural penicillin

Penicillin G

Acid resistant penicillin

Penicillin V

Penicillinase resistant penicillin

Methicillin

β lactamase inhibitors

Clavulanic acid

Penicillin active against pseudomonas

Carboxy and ureidopenicillins

Extended spectrum penicillins

Aminopenicillins: Ampicillin Carboxypenicillin: Carbenicillin Ureidopenicillin: Piperacillin

a) Penicillin G

Antibacterial Spectrum: Streptococci, pneumococci, N. gonorrhoea, clostridia, M. TB, spirochaetes, actinomyces israeli, B. anthracis Mechanism of Action: Interfere with the synthesis of bacterial cell wall Adverse Effects:  Local irritancy and direct toxicity  Hypersensitivity reactions  Super infections  Jarisch-Herxhemier reactions Uses: i. Dental infections: periodontal abscess, periapical abscess, pulpitis ii. Medicinal uses: Gonorrhoea, syphilis, tetanus Preparations and Dose: Sodium penicillin G inj.: Procaine penicillin G inj.: Fortified procaine penicillin G inj.: Benzathine penicillin G:

Contraindications:  Allergies  Poor renal function

Benzyl pen 0.5,1 MU inj. 0.5,1 MU dry powders in vial 3+1 lac U vial Penidure LA 0.6, 1.2, 2.4 MU as dry powder in vial


Drug Interactions: Oral contraceptives Pregnancy category: B Trade Names: PENCIP, PENTIDS, SODICILLIN

b) Ampicillin

Antibacterial Spectrum: E. coli, proteus, salmonella, shigella and many Gram positive organisms like cocci, bacilli etc. Mechanism of Action: Interfere with the synthesis of bacterial cell wall Adverse Effects:  Diarrhoea  Rashes Drug Interactions: Oral contraceptives Uses: i. ii. iii. iv. v.

Urinary tract infection Respiratory tract infection Meningitis, gonorrhoea SABE, typhoid fever Bacillary dysentery, septicemias

Contraindications:  Allergies  Poor renal function Dosage: 0.5-2g oral/I.M/I.V every 6 hrs for adults 25-50 mg/kg/day for children Trade Names: AMPISYN, AMPILIN, AMPI-500, ALFACILLIN, AMPICILLIN

c) Amoxicillin

Similar to ampicillin in all aspects except:  Oral absorption is better  Incidence of diarrhea  It is less active against Shigella and H. influenzae Dosage: 250-500mg TDS given for 5 days


Uses: Choice of drug for prophylaxis of local wound infection as well as distant i nfection following dental surgery Trade Names: MOX, AMOX, AMOXIL, AMOXIPEN, AUGMENTIN (Amoxicillin and clavulanic acid)

d) Methicillin

MRSA (methicillin resistant staph. aureus) are organisms resistant to methicillin. Drug of choice: vancomycin/linezolid. Ciprofloxacin can also be used

2. CEPHALOSPORINS

Mechanism of Action: Interfere with the synthesis of bacterial cell wall Classification: a) First Generation: 



Effective against gram positive cocci, including penicillinase producing staph, most anaerobes and community acquired infections caused by E.coli, Proteus and klebsiella Examples are: Cefalexin, Cefadroxil

b) Second Generation:   

Show increased antibacterial activity Cefmandole has markedly increased activity. But it has less activity against strep. Cefactor, increased activity against H.influenzae

c) Third Generation: 



Ceftriaxone shows high efficacy in bacterial meningitis, multi resistant typhoid fever, complicated urinary tract infections, abdominal sepsis and septicemias Examples are: Cefpodoxime proxetil, cefoperazone

d) Fourth Generation: 

Examples are: Cefepime, cefpirome

Dosage: 250-1000 mg q 6 h x 7-10 days Uses: i. Dental infections ii. General medical uses like meningitis, typhoid etc


Adverse Effects:  Pain after I.M injection  Diarrhoea  Hypersensitivity reactions  Nephrotoxicity  Bleeding  Neutropenia and thrombocytopenia Contraindications:  Allergies  Poor renal function Drug Interactions: Probenecid Pregnancy Category: B

3. TETRACYCLINES

Antibacterial Spectrum: Cocci: N. gonorrhoea and N. menigitidis Bacilli: Clostridia and anaerobic bacilli, H. ducreyi Some spirochetes, mycoplasma, actinomyces Mechanism of Action: Inhibit protein synthesis by binding to 30S ribosomes - prevent aminoacyl transfer RNA from entering the acceptor sites on the ribosome Uses: i. ii. iii.

Orodental infections Gingivitis Periodontal ligament related diseases

Adverse Effects:           

Irritative effects Liver damage Kidney damage Phototoxicity Teeth and bones: Enamel hyperplasty, inhibition of fibula growth, dental caries, brown discolouration, formation of calcium tetracycline crystals Antianaboilic effects Increased intracranial pressure Diabetes insipidus Vestibular toxicity Hypersensitivity Superinfection

Dosage: 100 mg qd-bid x 7-14 days


Contraindications:  

Food Pregnancy

Drug Interactions: Anti-epileptics Pregnancy category: D

4. CHLORAMPHENICOL

Antibacterial Spectrum: H. influenzae, salmonella, klebsiella along with those sensitive to tetracycline Mechanism of Action: Inhibit protein synthesis binding to 50S subunit Uses: i. ii. iii. iv.

Enteric fever H. influenzae meningitis Anaerobic reactions Intraocular infections

Adverse Effects:     

Bone marrow depression Hypersensitivity reactions Irritative effects Superinfections Gray baby syndrome

Dosage: Daily dose not to exceed 2–3 g; duration of therapy to be < 2 weeks, total dose in a course < 28 g Contraindications: Pregnancy Drug Interactions: 

Inhibits metabolism of tolbutamide, chlorpropamide, warfarin, cyclophosphamide and phenytoin  Phenobarbitone, phenytoin, rifampin enhance metabolism  Antagonize the cidal action of β-lactams/aminoglycosides on certain bacteria Pregnancy category: D


5. AMINOGLYCOSIDES

Antibacterial Spectrum: Gram negative bacilli, H.ducreyi, yersinia pestis, gram positive cocci, enterococci Mechanism of Action: Inhibit protein synthesis Uses: i. ii. iii. iv. v. vi.

Tuberculosis Plaque Tularemia Brucellosis Enterococcal infections Subacute bacterial infections

Adverse Effects:     

Ototoxicity Nephrotoxicity Neuromuscular blockade Allergy Superinfection

Dosage: 0.5-1 gm by I.M injection Contraindications:  

Pregnancy (risk of foetal ototoxicity) Concurrent use of other ototoxic drugs, e.g. high ceiling diuretics, minocycline.  Concurrent use of other nephrotoxic drugs, e.g. amphotericin B, vancomycin Precautions: 

Patients past middle age  Kidney damage Drug Interactions: Cautious use of muscle relaxants

Trade Names: GENTACIL, GENTYCIN, GENTAMICIN

6. MACROLIDES

Antibacterial Spectrum: Streptococcus, staphylococcus, gonorrhea, clostridia


Mechanism of Action: Act by inhibiting protein synthesis by binding to the bind to the 23S rRNA of 50S ribosomal subunits Uses: i. ii.

Dental infections: Periodontal, periapical abscess, necrotizing ulcerative gingivitis, gingival cellulites General medical uses: Pharyngitis, tonsillitis, rheumatic fever

Adverse Effects:   

Gastrointestinal problems Hypersensitivity Reversible hearing impairment

Dosage: Erythromycin: 250-500 mg 6 hourly (max.4g/day), children 30-60-mg/kg/day Azithromycin: 500 mg once daily 1hr before or 2hrs after food for 3 days Precautions: Poor hepatic function Drug Interactions: Cytochrome P-450 Pregnancy category: B

7. METRONIDAZOLE

Antibacterial Spectrum: Entamoeba histolytica, giardia lamblia, anaerobic bacteria, like clostridium, spirochetes, peptococcus Mechanism of Action: Reduced intermediate interacts and breaks the bacterial or parasitic DNA Adverse Effects:   

Anorexia, nausea, metallic taste, abdominal cramps Headache, dryness of mouth, rashes, and Glossitis (rare) Thrombophlebitis of the injected vein

Uses: i. ii. iii. iv. v.

Orodental infections Drug of choice in acute necrotizing ulcerative gingivitis Periodontitis, pericoronitis, acute apical infections, brain abscess Drug of choice for all forms of anaerobic infections, acute dysentery, liver abscess Drug of choice for intestinal giardiasis and trichomonas vaginitis


Dosage: 200-400 mg TDS (15-30mg/kg/day) Trade Names: METROGYL, FLAGYL Contraindications: 

Pregnancy  Chronic alcoholism Precautions: Poor hepatic function Drug Interactions:  

EtOH Warfarin  Li+ Pregnancy category: D

8. FLUOROQUINOLONES

Antibacterial Spectrum: All organisms are susceptible except some strep, anaerobic cocci, m ycobacterium Mechanism of Action: Bind to A subunit of DNA gyrase with high affinity and interfere with strand cutting and resealing functions Adverse Effects:  

GIT: Nausea, vomiting, bad taste, anorexia CNS: Dizziness, headache, restlessness, anxiety  Skin/hypersensitivity Uses: i. ii. iii. iv.

Urinary tract infections Gonorrhea Soft tissue, bone and joint infections especially gram negative organisms Community acquired pneumonia

Dosage: Ciprofloxacin 250-500 mg QD x 7-10 days Trade Names: BIOCIP, CIP, CIPLOX, CIPLO Contraindications:  

Children (damage of the cartilage in weight bearing joints) Pregnancy

Drug Interactions:  

Probenacid Warfarin


Pregnancy category: C

9. CLOTRIMOXAZOLE

Combination of trimethoprim and sulfamethoxazole (1:20) Antibacterial Spectrum: Same as sulfonamide but include salmonella typhi, klebsiella, enterobacter Mechanism of Action: Inhibit bacterial dihydrofolate reductase Uses: i. ii. iii.

Pneumocystis carnii pneumonia in AIDS patients Tonsillitis, Pharyngitis, sinusitis Urinary tract infections, orodental infections

Adverse Effects:    

Methamoglobinemia Blood dyscarasis Nausea, vomiting, stomatitis, headache and rashes Neonatal hemolysis

Contraindications: Pregnancy


Newer Antibiotics i. ii. iii. iv. v. vi.

Ceftolozane/tazobactam: Antipseudomonal cephalosporin/ β-lactamase inhibitor combination (cell wall synthesis inhibitor) Ceftazidime/avibactam: Antipseudomonal cephalosporin/ β-lactamase inhibitor combination (cell wall synthesis inhibitor) Ceftaroline/avibactam: Anti-MRSA cephalosporin/ β-lactamase inhibitor combination (cell wall synthesis inhibitor) Plazomicin: Aminoglycoside (protein synthesis inhibitor) Eravacycline: A synthetic tetracycline derivative / protein synthesis inhibitor targeting the ribosome Brilacidin: Peptide defense protein mimetic (cell membrane disruption)

Misuse in Dentistry Treatment of Nonresponsive Infections: 

Diseases caused by viruses are self-limited

Therapy of Fever of Unknown Origin:  

Fever persisting for 2 or more weeks – only 1/4th are due to infections Require treatment with agents that are not used commonly for bacterial infections, surgical drainage or prolonged courses of pathogen-specific therapy  May mask an underlying infection, delay the diagnosis, and prevent identification of the infectious pathogen  Noninfectious causes Inappropriate Reliance on Chemotherapy Alone:    

Drainage, debridement, and removal of foreign body Misuse in Dentistry Improper Dosage: Dosing errors (wrong frequency of administration or use of either an excessive or a subtherapeutic dose)  Excessive amounts can result in significant toxicities  Too low a dose may result in treatment failure or resistance Lack of Adequate Bacteriological Information:    

Bacterial cultures and Gram stains of infected material Frequent use of drug combinations or drugs with the broadest spectra Agents are selected more likely by habit than for specific indications Dosages employed are routine rather than individualized


Conclusion Antibiotic therapy is an art and a science. There are so many confounding variables (such as suspected pathogen, ability to establish drainage, pharmacokinetic properties of the drug, mechanism of action of the antibiotic, virulence of the infection, the current health status of the host, and host defense mechanisms), that it is not possible to make antibiotic therapy into a mechanistic technologic science. The most important decision for the dental practitioner to make is not only which antibiotic to use but whether to use one at all.

References i. ii. iii. iv. v.

Essentials of Medical Pharmacology, 6th Edition – K. D. Tripathi Goodman & Gilman’s The Pharmacological Basis of Therapeutics, 11th Edition Pharmacology and Pharmacotherapeutics - R. S. Satoskar Manoj Kumar Jain, Sheetal Oswal K. Antibiotics in Dentistry – An Art and Science. Annals of Dental Specialty 2013; 1(1):20-25. Prevention of Infective Endocarditis: Guidelines From the American Heart Association, by the Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease. Circulation, 2007; 116: 1736-1754.

Online sources: http://www.medclik.com http://en.wikipedia.org/wiki/Antibacterial

Antibiotics in Dentistry

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