Antimicrobial agents /prosthodontic courses

ANTIMICROBIAL
AGENTS
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.comwww.indiandentalacademy.com

ANTIMICROBIAL AGENTSANTIMICROBIAL AGENTS
 IntroductionIntroduction
 DefinitionDefinition
 HistoryHistory
 Mechanism of action and classificationMechanism of action and classification
 IndicationsIndications

 Routes of administrationRoutes of administration
Antimicrobial drugsAntimicrobial drugs
Prophylaxis against bacterial endocarditisProphylaxis against bacterial endocarditis
Newer antimicrobial agentsNewer antimicrobial agents
Complication associated with use of antimicrobial agentsComplication associated with use of antimicrobial agents
Contd..

Indian Dental academy
• www.indiandentalacademy.com
• Leader continuing dental education
• Offer both online and offline dental
courses

INTRODUCTIONINTRODUCTION
 Antimicrobial agentsAntimicrobial agents
• Management of infection in the oral cavity andManagement of infection in the oral cavity and
• Prevention of complications.Prevention of complications.
However their indiscriminate use can result inHowever their indiscriminate use can result in
serious complicationsserious complications

DEFINITIONS :
Drug : drug is any substance / product that is used / is
intended to be used to modify / explore physiological systems
/ pathological states for the benefit of one recipient.
Chemotherapy : it is the treatment of systemic infection /
malignancy with specific drugs that have selective toxicity for
the infecting organism / malignant cell with no / minimal
effects on the host cells.

Antibiotic agent : Against life
(Greek-anti means against and biosis means life).
Chemical substances produced by microorganisms that
have the capacity in dilute solutions, to produce antimicrobial
action.
Antimicrobial agent :
Substances that will suppress the growth /
multiplication of microorganisms. antimicrobial agents may
be antibacterial, antiviral / antifungal.
substances that destroy or suppress the growth / multiplication of bacteria. They are
classified as antibiotic or synthetic agents.
 Pharmacodynamics :
what the drug does to the body.
 Pharmacokinetics :
what the body does to the drug.HistoryHistory
 In South America the Inca Indians actually practiced chemotherapy by treating malaria withIn South America the Inca Indians actually practiced chemotherapy by treating malaria with
cinchona bark.cinchona bark.
 During seventeenth century ipeac was introduced for the treatment of amebiasis.During seventeenth century ipeac was introduced for the treatment of amebiasis.
 Paul Ehrlich(1854-1915), referred as father of scientific chemotherapy,defined the fundamentalPaul Ehrlich(1854-1915), referred as father of scientific chemotherapy,defined the fundamental
principles of anti-infective therapy,discovered organic arsenicals used in the treatment of syphilisprinciples of anti-infective therapy,discovered organic arsenicals used in the treatment of syphilis
Antibacterial agent :

Over 2000 years ago Chinese used moldyOver 2000 years ago Chinese used moldy
curd in the treatment boils ,furuncles.curd in the treatment boils ,furuncles.
Alexander Fleming discovered penicillin inAlexander Fleming discovered penicillin in
1929 ever since they are most commonly1929 ever since they are most commonly
used anti-infective agentused anti-infective agent
In 1935 Domagk introduced sulfonamides and employedIn 1935 Domagk introduced sulfonamides and employed
successfully in the management of infectious processessuccessfully in the management of infectious processes,,

CLASSIFICATION
A) Mechanism of action :
1. Inhibit cell wall synthesis
• Penicillins
• Cephalosporins
• Vancomycin
• Bacitracin
2. Cause leakage from cell membranes
• Polypeptides – Polymycins, colistin, Bacitracin
• Polyenes – Amphotericin B, Nystatin

5. Inhibit DNA gyrase
• Fluoroquinolones – Ciprofloxacin
5. Interfere with DNA function
• Rifampacin
• Metronidozole
5. Interfere with DNA synthesis
• Idoxuridine
• Acyclovir
• Zidovudine

8) Interfere with intermediary metabolism
Sulfonamides
Sulfones
Ethambutol

B) Chemical structure
1. Sulfonamides and related drugs
• Sulfadiazine and others
• Sulfones – Dapsone (DDS), Paraaminosalicylic acid
(PAS).
2. Diaminopyrimidines
• Trimethoprim
• Pyrimethamine
3. Quinolones
• Nalidixic acid Ciprofloxacin etc
• Norfloxacin

4. Tetracycline's
• Oxytetracycline
• Doxycycline etc
4. Nitrobenzene derivative
• Chloramphenicol
4. β-lactam antibiotics
• Penicillins
• Cephalosporins
• Monobactams
• Carbapenems

7. Aminoglycosides
• Streptomycin
• Gentamicin
• Neomycin etc
7. Macrolide antibiotics
• Erythromycin
• Roxithromycin
• Azithromycin etc
7. Polypeptide antibiotics
• Polymyxin-B
• Colistin
• Bacitracin

10.Glycopeptides
• Vancomycin
• Teicoplanin
10.Oxazolidinone
• Linezolid
10.Nitrofuran derivatives
• Nitrofurantoin
• Furazolidone
10.Nitroimidozoles
• Metronidozole
• Tinidazole www.indiandentalacademy.comwww.indiandentalacademy.com

14.Nicotinic acid derivatives
• Isoniazid
• Pyrazinamide
• Ethionamide
14.Polyene antibiotics
• Nystatin
• Amphotericin-B
• Hamycin
14.Azole derivatives
• Miconazole
• Clotrimazole
• Ketoconazole

17.Others
• Rifampin
• Lincomycin
• Clindamycin
• Spectinomycin
• Sod. fusidate
• Cycloserine
• Viomycin
• Griseofulvin

C) Type of organisms against which primarily active]
1. Antibacterial
• Penicillins
• Aminoglycosides
• Erythromycin etc
2. Antifungal
• Griseofulvin
• Amphotericin B
• Ketoconazole
3. Antiviral
• Idoxuridine
• Acyclovir
• Zidovudine etc www.indiandentalacademy.comwww.indiandentalacademy.com

4. Antiprotozoal
• Chloroquine
• Pyrimethamine
• Metronidazole
• Diloxanide etc
4. Anthelmintic
• Mebendazole
• Pyrantel
• Niclosamide
• Diethyl carbamazine etc

D) Spectrum of activity
1. Narrow spectrum
• Penicillin G
• Streptomycin
• Erythromycin
2. Broad spectrum
• Tetracyclines
• Chloramphenicolwww.indiandentalacademy.comwww.indiandentalacademy.com

E) Type of action
1. Primarily
bacteriostatic
• Sulfonamides
• Tetracyclines
• Chloramphenicol
• Erythromycin
• Ethambutol
2. Primarily bactericidal
• Penicillins
• Aminoglycosides
• Rifampin
• Cotrimoxazole
• Cephalosporins
• Vancomycin
• Nalidixic acid
• Ciprofloxacin

F) Antibiotics are obtained from
1. Fungi
• Penicillin
• Cephalosporin
• Griseofulvin
2. Bacteria
• Polymyxin B
• Colistin
• Bacitracin
• Tyrothricin
3. Actinomycetes
• Aminoglycosides
• Tetracyclines
• Chloramphenicol
• Macrolides
• Polyenes

IndicationsIndications
1)1) Control and eradication infections of oral cavityControl and eradication infections of oral cavity..
2)2) Prophylaxis to prevent complications .Prophylaxis to prevent complications .
o Control and eradication of infections of oral
cavity.
While prescribing antibiotics clinician should considerWhile prescribing antibiotics clinician should consider
both systemic and local factors.both systemic and local factors.
Local factors;Local factors;
1) Swelling,1) Swelling,
2) Lymphadenitis,2) Lymphadenitis,
3) Trismus,3) Trismus,
4) Dyshagia4) Dyshagia www.indiandentalacademy.comwww.indiandentalacademy.com

 Systemic factors;Systemic factors;
1) Cellulitis.1) Cellulitis.
2) Osteomyelitis.2) Osteomyelitis.
3) Infections of salivary gland.3) Infections of salivary gland.
4) Compound fractures.4) Compound fractures.
5) Infected cysts.5) Infected cysts.
6) Infected oro-antral fistula.6) Infected oro-antral fistula.
7) Pericoronitis7) Pericoronitis

PROPHYLACTIC ANTIBIOTICS
Advantages :
• Prevention of infection
• Decreased patient morbidity
• Decreased patient mortality
• Decreased hospital stay
• Decreased medical costs
• Decreased total antibiotic usage

Disadvantages :
1) No reduction of infection, despite prophylaxis
2) Development of increased number of resistant
bacteria
3) Delayed onset of infection
4) Adverse effect on surgical technique
Note :
Effective is a short-term administration of a narrow-
spectrum antibiotic.

Principles for the use of prophylactic
antibiotics
1) Operative procedure must have a risk of significant
bacterial contamination and a high incidence of
infection.
2) The organism most likely to cause the infection must be
known.
3) The antibiotic susceptibility of the causative organism
must be known.

Routes of drug administration;
Routes can be broadly divided into
1) Local routes
- Topical
- Skin
- Mucous membrane
- Deeper tissues

2) Systemic routes :
a) Oral :
• Oldest and commonest
• Safer, more convenient
• Noninvasive, often painless
• Need not be sterile
• Cheaper

b) Sublingual or buccal
• Drug is placed under the tongue or crushed in the
mouth and spread over the buccal mucosa.
• Absorption is rapid – action can be produced in
minutes.
Advantage :
• Liver is bypassed and drugs with high first pass
metabolism can be absorbed directly into systemic
circulation.
• Drugs given sublingually are – nitroglycerine,
isoprenaline, methyltestosterone, clonidine.

c) Rectal :
• Irritant and unpleasant drugs can be administered
• When the patient is having recurrent vomiting.
• Absorption is slower, irregular and often
unpredictable.
• Absorption is 50%
• Rectal inflammation can result from irritant drugs.
• Aminophylline, indomethacin, paraldehyde, diazepam
are drugs given rectally.www.indiandentalacademy.comwww.indiandentalacademy.com

d) Cutaneous :
• Highly lipid soluble drugs can be applied over the skin
for slow and prolonged absorption.
• The liver is bypassed
• Drugs is incorporated in an ointment
e) Inhalation :
• Volatile liquids and gases are given by inhalation for
systemic action
• Absorption is fast and action is very rapid.
• When administration is discontinued the drug diffuses
back and is rapidly eliminated in expired air.
• Irritant vapours can cause inflammation of respiratory
tract and increase secretion. (Ether)
Eg : General anesthesia

f) Nasal :
• The mucous membrane of the nose can readily absorb
many drugs,
• Digestive juices and liver are bypassed.
• Certain drugs like desmopressin applied as a spray or
nebulized solution have been used by this route.
(Par-beyond, enteral – intestinal)
• Administered by injection – directly into the tissue fluid
– cross the intestinal mucosa.
• Overcome the limitations of oral administration.
• Action is faster (valuable in emergencies)
• Gastric irritation and vomiting are not provoked.
• Employed in unconscious, uncooperative or vomiting
patient.
.
g) Parenteral :

Disadvantages :
• Preparation has to be sterilized
• Costlier
• Technique is invasive and painful
• Assistance of another person
• Chances of local tissue injury
Important parenteral routes are
i) Subcutaneous
• Drug is deposited in the loose subcutaneous tissue
which is richly supplied by nerves.
• Absorption is delayed
• Route is avoided in soft patients and who are using
vasoconstrictor. www.indiandentalacademy.comwww.indiandentalacademy.com

ii) Intramuscular :
• Drug is injected in large skeletal muscles.
• Deltoid, triceps, gluteus maximus, rectus femoris etc.
• Muscle is less richly supplied with sensory nerves
and is more vascular
• Absorption is faster.
• Less painful
• Self injection is often impracticable

iii) Intravenous :
• Infused slowly over hours in one of the superficial veins.
• Drug directly reaches into the blood stream and effects
are produced immediately (emergency)
• Irritant drugs can be injected through i.v.
• But hazards are – thrombophlebitis of the infected vein
and necrosis of adjoining tissues
• This can be minimized by diluting the drug and injecting
into a running I.v. line.
• The dose of the drug required is smallest.
iv) Intradermal injection :
• Drug is injected into the skin rising a bleb. (BCG, small
pox vaccine)

SULFONAMIDES
 First antimicrobial agents (AMAs) effective against
pyogenic bacterial infections.
 Parent drug was first synthesized in 1908 from azo dyes,
and it was not used until 1932.
 Is a generic name for derivatives of PARA-
AMINOBENZENE SULFONAMIDE. They contain a
sulfonamido (SO2 NH2) group.

• Mechanism of action :
 Sulfonamides, being structural analogues of PABA,
inhibit bacterial foliate synthetase – FA is not formed and
a number of essential metabolic reactions suffer.
 Sulfonamides competitively inhibit the union of PABA.
 Being chemically similar to PABA, the sulfonamide may
itself get incorporated to form an altered foliate which is
metabolically injurious.
 Human cells also require FA but they utilize preformed
FA supplied in diet and are unaffected by sulfonamides.

Pharmacokinetics :
Sulfonamides are rapidly and nearly completely
absorbed from G.I.T.
They highly protein bound members and are long acting.
Widely distributed in the body
Are excreted mainly by the kidney
Adverse effects :
Urinary tract – crystallurea, albuminurea, hematuria.
Hematopoietic system – acute hemolytic anemia
Hypersensitivity reaction - Rashes, Steven Johnson
syndrome

Uses :
UTI
Toxoplasmosis
Acute bacillary dysentery
Meningococcal meningitis
Ulcerative colitis
Chancroid
Trachoma and inclusion conjunctivitis
Used in prophylaxis

PENICILLINS
Most important antibiotics first extracted from the mould
PENICILLIUM NOTATUM
First used in 1941 clinically and was a miracle
drug with a least toxic effect.

CLASSIFICATION OF PENICILLINS
1. Natural penicillin
• Penicillin G (benzyl penicillin)
• Procaine penicillin G
• Benzathine penicillin G
2. Acid resistant penicillin
• Phenoxymethyl penicillin (penicillin V)
• Phenoxyethylpenicillin (phenethecillin)
3. Penicillianse – resistant penicillins
• Acid labile – methecillin, nafcillin, cloxacillin,
dicloxacillin
• Acid resistant – flucloxacillin

4. Penicillins effective against gram positive and some
gram-negative organisms
• Ampicillin
• Amoxycillin
• Talampicillin
4. Extended spectrum penicillins
• Carboxypenicillins – carbenicillin, ticarcillin
• Ureidopenicillins – piperacillin, mezlocillin
• Amidino penicillins – mecillinam, pivmecillinam
4. Penicillins with betalactamase inhibitors
• Amoxycillin – clavulanic acid (Augmentin)

BENZYL PENICILLIN (PENCILLIN G)
• PnG is a narrow spectrum antibiotic; activity is limited
primarily to gram positive bacteria
• Is available in the form of water soluble sodium and
potassium salts
• This salts in a dry state are stable at room temperature for
years. The aqueous solution however requires refrigeration
and deteriorates considerably with in 72 hours.
Antibacterial activity
• Most potent AMA, inhibits the growth of susceptible
organism.
• Mainly gram +ve, gram –ve cocci and some gram +ve
bacilli with exception of enterococci.

Mechanism of action :
• Bactericidal drug effective mainly against multiplying
organisms.
• Penicillin requires cell wall that contains peptidoglycans.
• Peptidoglycans is heteropolymeric component of cell
wall provides rigid mechanical, cross linked lattice like
structure. .
• Penicillins bind to these proteins and inactivate them,
thereby preventing the synthesis and cross linkage.
• This weakens bacterial cell wall and makes organism
vulnerable to damage.

Absorption fate and excretion :
• About 1/3 of drug is activated on oral administration.
• Absorbed from the duodenum.
• Because of the inadequate absorption the oral dose
should be 4/5 times larger than the intramuscular dose.
• As food interferes with its absorption PnG should be
given orally at least 30 min after food or 2 to 3 hours
before food.
• B. Penicillin in aqueous solution is rapidly absorbed after
SC or IM administration.
• Peak plasma level of 8 to 10 units per ml is reached with
in 15 to 30 min and drug disappears from plasma with in
3-6 hours.

• Widely distributed in the body and significant
amounts appear in liver, bile, kidney, joint fluid and
intestine.
• PnG is excreted mainly by the kidney but in small
part in the bile and other routes.
• 50% drug is eliminated in urine with in first hour.
Preparation and dose :
•PnG inj 0.5-5 MU i.m or i.v 6-12 hours
• Procaine penicillin inj 0.5, 1 MU dry powder in vial

ADVERSE REACTIONS :
a) Miscellaneous reactions :
• Nausea and vomiting on oral PnG
• Sterile inflammatory reaction at the site of IM inj.
• Prolonged IV administration may cause
thrombophlebitis
• Accidental IV administration of procaine PP cause
anxiety, mental disturbances paraesthesia and
convulsions
a) Intolerance :
• Major problem with PnG includes idiosyncratic,
anaphylactic and allergic reactions

c) Other allergic reactions are
• Skin rashes
• Serum sickness
• Renal disturbance
• Hemolytic disturbance
• Anaphylaxis
• Jarisch herxheimer reaction
• Super infection
• Hyperkalemia
• Acute non allergic reaction

Uses :
PnG is the drug of choice for infections
1. Streptococcal infections
2. Pneumococcal infections
3. Meningococcal infections
4. Gonorrhoea
5. Syphilis
6. Diphtheria
7. Tetanus and gas gangrene
8. Prophylactic uses

SEMI SYNTHETIC PENICILLINS
The major drawbacks of benzyl penicillin are :
1. Inactivation by the gastric hydrochloric acid
2. Short duration of action
3. Poor penetration into CSF
4. Activity mainly against gram +ve organism
5. Possibility of anaphylaxis
P.chrysogenum produces natural penicillins which produce
the 6 amino-penicillanic acid (6-APA) nucleus.
The attachment of side chains are inhibited and instead
various organic radicals can be substituted.

I) Acid resistant pencillins :
1. Potassium phenoxymethyl penicillin (penicillin V)
• Similar antibacterial spectrum like benzyl penicillin.
• More active against resistant staphylococci
• Less inactivated by the gastric acid.
• Plasma levels achieved is 2 to 5 times higher than
benzyl penicillin.
• 50-70% is bond to plasma proteins.
• 25% of drug is eliminated in urine
• Available as 60 & 125 mg tablets..
• This can be used in less serious infections
(pneumocci and streptococci).

Dose : infants 60 mg, children 125-250 mg given 6 hourly
2. Potassium phenoxyethyl penicillin and
3. Azidocillin
Both have similar properties to penicillin V and no difference
in the antibacterial effect

II) Pencillinase resistant pencillins :
1. Methicillin
1. Effective in staphylococci
2. It is given IM or IV (slow) in the dose of 1 gm every 4-
6 hours.
3. Hematuria, albuminurea and reversible interstitial
nephritis are the special adverse effect of methicillin.
2. Cloxacillin
1. Weaker antibacterial activity.
2. Distributed thro out the body, but highest s
concentration in kidney and liver. 30% excreted in
urine.
3. Oral dose for adults 2-4 gm divided into 4 portions
children 50-100mg/kg/day.
4. IM adults 2-12 gm/day, children 100-300 mg/kg/day
every 4-6 hours. www.indiandentalacademy.comwww.indiandentalacademy.com

Oxacillin, Dicloxacillin, Flucloxacillin are other isoxazolyl
penicillins, similar to cloxacillin, but not marketed in India.
Naficillin :
More active than methicillin and cloxacillin but less active
than PnG
80% of drug bonds with plasma proteins excreted by liver in
patients with renal failure.
Dose is similar to cloxacillin.

III) Extended spectrum penicillin's :
1. Amino penicillin's
1. Ampicillin –
• Antibacterial activity is similar to that of PnG that is
more effective than PnG against a variety of gram-ve
bacteria
• Drug is effective against H.influenzae strep. viridans,
N.gonorrhea, Salmonella, shigellae, Klebsiella and
enterococci.
Absorption, fate and excretion :
• Oral absorption is incomplete but adequate
• Partly excreted in bile and partly by kidney

Dose : 0.5-2 gm oral/IM or IV depending on severity of
infection every 6 hours
Children : 25-50 mg/kg/day
USES :
• Urinary tract infections
• Respiratory tract infections
• Meningitis
• Gonorrhoea
• Typhoid fever
• Bacillary dysentry
• Septicemias
• SBE

Adverse effects :
• Diarrhoea is frequent
• Skin rashes is more common
• Unabsorbed drug irritates lower intestines
• Patient with history of hypersensitivity to PnG should
not be given Ampicillin.

AMOXYCILLIN :
• This is a semisynthetic penicillin
• (amino-p-hydroxy-benzylpencillin)
• Antibacterial spectrum is similar to ampicillin but less
effective than ampicillin for shigellosis.
• Oral absorption is better; food does not interfere; higher
and more sustained blood levels are produced.
• It is less protein bond and urinary excretion is higher than
that of ampicillin.
• Incidence of diarrhoea is less

Dose : 0.25-1 g TDS oral;
USES :
• Typhoid
• Bronchitis
• Urinary infection
• SBE
• Gonorrhoea

Adverse effects :
• Pain-thrombophebitis
• Rashes and Diarrhoea
Uses :
• Mixed aerobic-anaerobic infections
• Gonorrhoea
• Skin/soft tissue infections
 Obtained from a strain of streptomyces erythreus.Obtained from a strain of streptomyces erythreus.
 It may be bactericidal or bacteriostatic dependingIt may be bactericidal or bacteriostatic depending
concentration.concentration.
 Mechanism of action,Mechanism of action,
acts by interfering with with protein synthesisacts by interfering with with protein synthesis
 Uses;Uses;
1) In odontogenic infections.1) In odontogenic infections.
2) Most preferred drug for patients allergic to penicillin.2) Most preferred drug for patients allergic to penicillin.
ErythromycinErythromycin

 DosageDosage;;
Adult dose - 250mg every six hours.Adult dose - 250mg every six hours.
Child dose - 20 to 40 mg./kg body wt.Child dose - 20 to 40 mg./kg body wt.
 Oral preparations available in suspensions capsules andOral preparations available in suspensions capsules and
drops.drops.
 Adverse reactionsAdverse reactions;;
1) Gastric disturbances.1) Gastric disturbances.
2) Nausea.2) Nausea.
3) vomiting.3) vomiting.
4) Epigastric distress4) Epigastric distress
5) Hepatoxicity when lauryl sulfate salt of erythromycin5) Hepatoxicity when lauryl sulfate salt of erythromycin
is used.is used.

TETRACYCLINES
 Tetracyclines are napthacene derivatives.
 The napthacene nucleus is made up by fusion of 4
partially unsaturated cyclohexane radicals and hence the
name tetracyclines.
 Tetracycline's are bacteriostatic.

On the basis of chronology of development,
convenience of description, divided into 3 groups.
Group I Group II
Tetracycline Demeclocyline
Oxytetracycline Methacycline
Group III
Doxycycline
Minocycline
.

Tetracyclines are thought to inhibit bacterial protein
synthesis by binding to the 30 S bacterial ribosome and
preventing the access of Aminoactyl RNA to the
acceptor (A) sites on the mRNA ribosome complex
Antimicrobial activity :
Gram +ve and –ve cocci are sensitive
Gram +ve bacilli are inhibited
Enterobactereae are highly resistant
Spirochetes and Borrelia are quite sensitive
All rickettsiae and chlamydiae are highly sensitive
Mechanism of action :

Pharmacokinetics :
 Incompletely absorbed from GIT
 Absorption is impaired by iron or zinc salts
[due to chelation of cations]
 They cross the placenta and enter fetal circulation and
amniotic fluid
 Widely distributed in liver ,bone marrow and spleen
 They accumulate in dentine and enamel of unerupted
teeth
 Primarily excreted in urine through kidney

Adverse effects :
GIT- Epigastric burning, nausea, vomiting, Diarrhoea
Hepatoxicity
Renal toxicity
Effects on teeth-Orthophosphate complex
Thrombophlebitis
Hypersensitivity Reactions
Super infection

Precaution :
 Not to be used in pregnancy, lactation and in children
 Avoided in patients on diuretics
 Used cautiously in renal and hepatic insufficiency
 Beyond expiry date should not be used
 Do not mix injectable Tc with Pn- inactivation occurs
.

Uses :
 Mixed infections
 Venereal diseases
 Cholera, Brucellosis, Plague, Rickettsial infections
 Alternate to Pn / Ap, Ciprofloxacin, Azithromycin
 Other situations –UTI, Amoebiasis, chronic lung disease
Dosage ;
Chlortetracycline, Oxytetracycline, and
Tetracycline is 250mg every six hours for
adults.
Child dose:- 20 to 40mg/kg. body wt/day

STREPTOMYCIN
• Streptomycin was initially obtained from streptomyces
griseus
• It is a bactericidal agent and effective against
mycobacterium.
Therapeutic uses :
 Bacterial endocarditis
 Tuberculosis
 Tularemia, plague, Brucellosis

Adverse effects :
Anaphylaxis is very rare.
Auditory disturbances are less common.
Streptomycin has the lowest nephrotoxicity.
Hypersensitivity reactions are rare ; rashes ; eosinophilia.
Topical use is contraindicated
Super infections are not significant.
Paresthesias are occasional.
Dosage : .
Acute infections : 1g I.m. BD for 7-10 days for adults.
40mg/kg/day divided into two
doses IM

CHLORAMPHENICOL
• Was the first broad spectrum antibiotic discovered.
• It is originally obtained from streptomyces venezuelae.
• It is now produced synthetically.
• It is unique among natural compounds because it
contains a NITROBENZENE moiety and is a derivative of
DICHLOROCETIC ACID.
• It acts by inhibiting protein synthesis (by binding
reversibly to the 50s ribosomal subunit).

Antimicrobial activity :
Broad spectrum antibiotic
Active against Salmonella, H influenza, Klebsiella
Less active Gram +ve cocci, spirochetes
Inactive against Entamoeba and Plasmodia, Pseudomonas,
Viruses and Fungi
Pharmacokinetics
Rapidly and completely absorbed on oral admins
Chloramphenicol is eliminated by conversion into active
metabolite Glucoronid, then excreted in urine

Dose :
Oral – 250 -500mg 6hrly
Children 25 – 50mg /kg/day
Adverse effects :
Bone marrow depression
Hypersensitivity reactions
Irritative effects
Super infections
Gray baby syndrome

Uses :
Typhoid fever (S.typhi)
Bacterial meningitis (H.influenzae)
Anaerobic infections
Rickettsial disease (e.g.. Rocky mountain spotted fever)
Brucellosis
UTI
 Lincomycin is synthesized by streptomyces lincolnensis.Lincomycin is synthesized by streptomyces lincolnensis.
 It is bacterostatic and bactericidal.It is bacterostatic and bactericidal.
 Uses;Uses;
odontogenic infections caused by streptococci andodontogenic infections caused by streptococci and
staphylococci.staphylococci.
 Adverse reaction;Adverse reaction;
diarrhea,diarrhea,
abdominal cramps,abdominal cramps,
jaundice,jaundice,
leucopoenia.leucopoenia.
LincomycinLincomycin

 Dosage;Dosage;
Adult dose - 500mg for every six hours orally.Adult dose - 500mg for every six hours orally.
child dose - 30 to 60 mg./kg.per day in four equallychild dose - 30 to 60 mg./kg.per day in four equally
divided doses.divided doses.

ANTIFUNGAL ANTIBIOTICS
These drugs used for superficial and deep fungal infections.
Nystatin
It is derived from streptomyces noursei.
It is both fungistatic and fungicidal.
Antifungal activity :
 Candida, Histoplasma, Blastomycoses, Trichophyton
and Microsporum audouini are sensitive.

 It combines with the cell membrane of the yeast and
interferes with vital cellular processes like respiration
and glucose utilisation.
Adverse reactions : large doses may cause gastro-
intestinal distress or diarrhea
Preparations and dosage :
 Nystatin suspension contains 100,000 units of nystatin
per ml. Oral topical application is usually made 3 times a
day.
Therapeutic uses :
 It is effective in treatment of localized candidiasis .
 Treatment schedule recommended.(1960)Treatment schedule recommended.(1960)
 For two days before dental procedure,For two days before dental procedure,
50,000 units of buffered penicillin G or phenoxymethyl50,000 units of buffered penicillin G or phenoxymethyl
penicillin ,orally four times a day.penicillin ,orally four times a day.
 Day of dental procedure,Day of dental procedure,
50,000 units of buffered penicillin G or phenoxymethyl50,000 units of buffered penicillin G or phenoxymethyl
penicillin,orally four times a day,supplemented by 60,000penicillin,orally four times a day,supplemented by 60,000
units of crystalline penicillin I.M.one hour before dentalunits of crystalline penicillin I.M.one hour before dental
procedure.procedure.
 Two days following dental procedureTwo days following dental procedure
50,000 units of penicillin50,000 units of penicillin G or penicillin V,four times aG or penicillin V,four times a
day.day.
Prophylaxis against BacterialProphylaxis against Bacterial
Endocarditis.Endocarditis.

 Oral penicillin,Oral penicillin,
50,000 units buffered penicillin G or penicillin V orally50,000 units buffered penicillin G or penicillin V orally
four times a day for two before dental procedure,on offour times a day for two before dental procedure,on of
dental procedure, and on two following days.dental procedure, and on two following days.
 If patient sensitive to penicillin,erythromycin is used.If patient sensitive to penicillin,erythromycin is used.
Adult dose; 250mg four times a day.Adult dose; 250mg four times a day.
Child dose; 40mg/kg of body wt.Child dose; 40mg/kg of body wt.

Newer anti-microbial agentsNewer anti-microbial agents
 Cephalexin,Cephalexin,
 Gentamycin,Gentamycin,
 Carbenicillin.Carbenicillin.
 These agents are indicated only for certain specificThese agents are indicated only for certain specific
infections.infections.

COMPLICATIONSCOMPLICATIONS
 Sensitivity by the patient to the agent,Sensitivity by the patient to the agent,
 Hypersensitivity and anaphylactic reactions,Hypersensitivity and anaphylactic reactions,
 Toxic reactions,Toxic reactions,
 Resistant strains of microorganisms,Resistant strains of microorganisms,
 Super infections.Super infections.

Sensitivity of the patientSensitivity of the patient
 When ever an antibiotic us prescribed the patient mayWhen ever an antibiotic us prescribed the patient may
become sensitized to it.become sensitized to it.
 This can result when a drug with a chemicalThis can result when a drug with a chemical
configuration to the antibiotic has given to the patient.configuration to the antibiotic has given to the patient.
 Another explanation is that patient had received theAnother explanation is that patient had received the
antibiotic as a concomitant in food or other substance.antibiotic as a concomitant in food or other substance.
Ex: PenicillinEx: Penicillin

Hypersensitivity and Anaphylactic reactionHypersensitivity and Anaphylactic reaction
 Patient sensitized to a drug,subsequent use could evokePatient sensitized to a drug,subsequent use could evoke
anaphylactic reactions.anaphylactic reactions.
 Anaphylactic reactions is characterized byAnaphylactic reactions is characterized by
1) Impalpable pulse,1) Impalpable pulse,
2) loss of consciousness,2) loss of consciousness,
3) facial edema or laryngeal edema and a generalized3) facial edema or laryngeal edema and a generalized
urticaria may accompany it.urticaria may accompany it.
 Prevention ; taking a detailed history regarding drugPrevention ; taking a detailed history regarding drug
therapy,administration of testing dose.therapy,administration of testing dose.

Toxic reactionsToxic reactions
 Almost every AM agent has the ability to produce aAlmost every AM agent has the ability to produce a
toxic reactions,which is caused due to over dosage oftoxic reactions,which is caused due to over dosage of
the drug.the drug.
Ex: 1) Chloramphenicol and sulfonamides leadingEx: 1) Chloramphenicol and sulfonamides leading toto
bone marrow depression,bone marrow depression,
2) Effect of tetracycline in renal insufficiency2) Effect of tetracycline in renal insufficiency

Development of resistant strainsDevelopment of resistant strains
 There are two main theories concerning the development ofThere are two main theories concerning the development of
drug resistance namelydrug resistance namely
1)Mutation1)Mutation
2)Adaptation2)Adaptation
 Most large bacterial colonies give rise to a few mutant strainsMost large bacterial colonies give rise to a few mutant strains
which are more resistant to a particular antibiotic than thewhich are more resistant to a particular antibiotic than the
rest of bacteria in the colony.rest of bacteria in the colony.

 These are thought due to genetic variations duringThese are thought due to genetic variations during
reproduction of the bacteria.The second and third generationsreproduction of the bacteria.The second and third generations
of these resistant mutant can become extremely resistant.of these resistant mutant can become extremely resistant.
 The second theory concerning drug resistance is due to theThe second theory concerning drug resistance is due to the
ability of the organism to develop alternate metabolicability of the organism to develop alternate metabolic
pathwayspathways

Super infectionSuper infection
 Due to the suppression of the sensitive bacteria by theDue to the suppression of the sensitive bacteria by the
antibiotic,there may be an over growth of other nonantibiotic,there may be an over growth of other non
susceptible MO which will produce an infection of greatersusceptible MO which will produce an infection of greater
consequence.consequence.
Ex: Development of yeast infections after prolong antibioticEx: Development of yeast infections after prolong antibiotic
therapytherapy

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