This document provides information about antibiotics, including their history, types, mechanisms of action, and uses. It begins with definitions and explains that antibiotics are substances produced by microorganisms that selectively kill or suppress the growth of bacteria and fungi. The document then discusses the early history of antibiotic discovery and highlights key findings and researchers throughout the 18th-20th centuries that led to modern antibiotics. It also provides summaries of several major classes of antibiotics like penicillins, cephalosporins, aminoglycosides, and tetracyclines and describes their mechanisms of action, spectra of activity, uses, and mechanisms of resistance.

2. WHAT ARE ANTIBIOTICS?
THE WORD “ANTIBIOTICS” MEANS “AGAINST LIFE”. THEY ARE SUBSTANCES
PRODUCED BY MICROORGANISMS WHICH SELECTIVELY KILL OR SUPPRESS THE
GROWTH OF MICROORGANISMS SPECIALLY BACTERIA AND FUNGI AT VERY LOW
CONCENTRATION.

3. HISTORY OF ANTIBIOTICS
Year Origin Description
1640 England
John Parkington recommended using mold
for treatment in his book on
1870 England
Sir John Scott Burdon-Sanderson observed
that culture fluid covered with mould did
produce bacteria
1871 England
Joseph Lister experimented with the
antibacterial action on human tissue on
he called Penicillium glaucium
1875 England
John Tyndall explained antibacterial
the Penicillium fungus to the Royal
1877 France
Louis Pasteur postulated that bacteria
kill other bacteria (anthrax bacilli)
1897 France
Ernest Duchesne healed infected guinea
from typhoid using mould (Penicillium
glaucium)
1928 England
Sir Alexander Fleming discovered enzyme
lysozyme and the antibiotic substance
penicillin from the fungus Penicillium
notatum
1932
German
y
Gerhard Domagk discovered
Sulfonamidochrysoidine (Prontosil )
During 1940's and 50's streptomycin, chloramphenicol, and
tetracycline were discovered and Selman Waksman used the
"antibiotics" to describe them (1942)
EARLY HISTORY
During ancient times;
•Greeks and Indians used moulds and other plants to treat infections.
•In Greece and Serbia, mouldy bread was traditionally used to treat wounds and
infections.
•Warm soil was used in Russia by peasants to cure infected wounds.
•Sumerian doctors gave patients beer soup mixed with turtle shells and snake skins.
•Babylonian doctors healed the eyes using a mixture of frog bile and sour milk.
•Sri Lankan army used oil cake (sweetmeat) to server both as desiccant and
antibacterial.
MODERN HISTORY

4. SIR ALEXANDER FLEMMING AND HIS DISCOVERY
Sir Alexander Fleming, a Scottish biologist, defined new horizons for modern antibiotics with his
discoveries of enzyme lysozyme (1921) and the antibiotic substance penicillin (1928). The discovery of
penicillin from the fungus Penicillium notatum perfected the treatment of bacterial infections such as,
syphilis, gangrene and tuberculosis. He also contributed immensely towards medical sciences with his
writings on the subjects of bacteriology, immunology and chemotherapy.
Alexander Fleming was born in Loudon, Scotland on 6 August, 1881 in a farming family. He carried on his
schooling at Regent Street Polytechnic after his family moved to London in 1895. He joined St. Mary's
Medical School and became research assistant to renowned Sir Almroth Wright after he qualified with
distinction in 1906. He completed his degree (M.B.B.S.) with gold medal in 1908 from the University of
London and lectured at St. Mart till 1914. He served as Captain during the World War I and worked in
battlefield hospitals in France. After the war he returned to St. Mary in 1918 and got elected Professor of
Bacteriology in 1928.
The Discovery of Penicillin
His research and study during his military career inspired him to discover naturally antiseptic enzyme in
1921, which he named lysozyme. This substance existed in tissues and secretions like mucus, tears and
egg-white but it did not have much effect on the strongly harmful bacteria. Six years later; as a result of
some intelligent serendipity, he stumbled on discovering penicillin. It was in 1928 when he observed
while experimenting on influenza virus that a common fungus, Penicillium notatum had destroyed
bacteria in a staphylococcus culture plate. Upon subsequent investigation, he found out that mould juice
had developed a bacteria-free zone which inhibited the growth of staphylococci. This newly discovered
active substance was effective even when diluted up to 800 times. He named it penicillin.
He was knighted in 1944 and was given the Nobel Prize in Physiology or Medicine in 1945 for his
extraordinary achievements which revolutionized the medical sciences

5. CLASSIFICATION
1. ACCORDING TO TYPE OF ACTION
BACTERIOSTATIC BACTERICIDAL
 TETRACYCLINE
 CHLORAMPHENICOL
 SULPHONAMIDE
 MACROLIDES
 PENICILLIN
 CEPHALOSPORIN
 AMINOGLYCOSIDES
2. ACCORDING TO SPECTRUM OF ACTIVITY
BROAD SPECTRUM
 TETRACYCLINES
 CHLORAMPHENICOL
NARROW SPECTRUM
 PENICILLIN
 AMINOGLYCOSIDES
3. ACCORDING TO SOURCE THEY ARE OBTAINED FROM
FUNGI BACTERIA ACTINOMYCETES
 PENICILLIN
 CEPHALOSPORIN
 AZTREONAM
 BACITRACIN
 AMINOGLYCOSIDES
 TETRACYCLINES
 CHLORAMPHENICOL
 MACROLIDES
4. RECENTLY 4 NEW CLASS OF ANTIBIOTICS HAVE BEEN
BROUGHT TO CLINICAL USE:
•Lipopeptides-daptomycin-Used in skin and skin
structure infections against gram positive infections
•Glycylcyclines-tigecycline-used in skin infections
caused by E.coli,Staphylococcus aureus,St. pyogens
•Oxazolidinones-linezolid-used in severe infections
caused by gram +ve bac resistant to other antibiotics
•Lipiarmycins-fidaxomicin-used for the treatment of
Clostridium difficile associated diarrhea.

6. FACTORS AFFECTING CHOICE OF ANTIBIOTIC
Factors affecting
selection
Organism related factors
•Clinical Diagnosis-Empirical
therapy
•Bacteriological reports
•Resistance to antibiotics
•Cross-resistance

8. β-LACTAM ANTIBIOTICS
PENICILLINS
First Antibiotic developed & used clinically. Acts as a bactericidal agent. It was originally
obtained from the fungus Penicillium notatum, but the present source is a high yielding
mutant of P. chrysogenum
Structure of pencillin:-
Site of action of penicillin

9. MECHANISM OF ACTION OF PENICILLIN
Β LACTAM ANTIBIOTICS INCLUDING PENICILLIN PRODUCE BACTERICIDAL
EFFECT BY INHIBITING CELL WALL SYNTHESIS IN BACTERIA. BACTERIAL CELL
WALL IS COMPOSED OF PEPTIDOGLYCAN .IT HAS GLYCAN CHAIN CROSS
LINKED BY PEPTIDE CHAIN. THE GLYCAN CHAIN IS COMPOSED OF AMINO
SUGARS NAM(N-ACETYL MURAMIC ACID)AND NAG(N-ACETYL GLUCOSAMINE)
A PENTAPEPTIDE LINKED TO NAM HAS A PENTAGLYCINE ATTACHED TO IT. THIS
PENTAGLYCINE IS CROSS LINKED WITH A PENTAPEPTIDE OF ADJACENT STRAND.
TRANSPEPTIDASE (PENICILLIN BINDING PROTEIN) CAUSES CROSS LINKING BETWEEN
THE PENTAGLYCINE OF 1STRAND TO 4RTH AMINO ACID(D ALANINE)OF ADJACENT
PENTAPEPTIDE, BY CLEAVAGE OF THE TERMINAL D ALANINE.THIS GIVES IT STABILITY
Β LACTAMS, STRUCTURAL ANALOGUES OF D ALANINE, INHIBIT
TRANSPEPTIDASE AND THUS PEPTIDOGLYCAN SYNTHESIS. CELL WALL
DEFICIENT FORMS ARE PRODUCED WHICH UNDERGO LYSIS. BETA LACTAMS
EXERT THUS THEIR CIDAL EFFECT WHEN THE BACTERIA IS ACTIVELY MULTIPLYING AND SYNTHESIZING
CELL WALL.
THE CELL WALL OF GRAM POSITIVE BACTERIA IS MAINLY COMPOSED OF HIGHLY CROSS LINKED
PEPTIDOGLYCAN, WHICH IS 50-100 LAYERS THICK.IN GRAM NEGATIVE BACTERIA THE PEPTIDOGLYCAN LAYER IS
ONLY 1-2 MOLECULES THICK. MOREOVER THERE IS AN OUTER LIPOPOLYSACCHARIDE LAYER. SO,GRAM
NEGATIVE ORGANISMS ARE LESS SUSCEPTIBLE TO PENICILLIN THAN GRAM POSITIVE.
 PENICILLIN HAS SEVERAL PREPARATIONS SUCH AS PENICILLIN G (NATURAL PENICILLIN), AMPIICILLIN,
AMOXICILLIN (SEMISYNTHETIC PENICILLINS). PENICILLIN G IS GIVEN BY I.V ROUTE. SEMISYNTHETIC
PENICILLINS ARE GIVEN BY MAINLY ORAL AND ALSO BY I.V, I.M. ROUTE.

10. Pneumococcal infections-In pneumonia ,mainly 3rd generation cephalosporin is preferable, but i.v. penicillin G(20-24 million
units/day)can be given for 7-10 days.
Streptococcal infections-penicillin G 6lac units i.m. once daily for 10 days as a single dose is used in the treatment of rheumatic
fever,streptococcal pharyngitis.
Syphilis-T.pallidum is very sensitive to penicillin so it is the drug of choice.
Gonococcal infections-Penicillin was drug of choice, but due to the emergence of resistant organisms it is not preferred.
Cephalosporins are used now a days.
Diphtheria-Penicillin G is used mainly to eliminate the carrier state in the acute upper respiratory tract infections caused by
C.diphtheria
Uses:-
Adverse Effects:-
oHypersensitivity reactions such as fever, asthma ,
anaphylactic reactions.
oPain and sterile abscess at the site of i.m injection.
oJarisch-Herxheimer reaction seen in syphilis patients while
penicillin therapy.It is an acute manifestations of signs and
symptoms of syphilis during penicillin therapy due to release
of endotoxins from the dead organisms. The symptoms are
fever, chills, hypotension,circulatory collapse etc. It is treated
with aspirin and corticosteroids
PROPHYLACTIC USES:-
• Rheumatic fever-The causative organism is
grp A β-haemolytic streptococcus for
rheumatic fever penicillin G is given in a
dose of 1.2million units i.m. once a month
and continued for life. Patients allergic to
penicillin is treated with erythromycin.
• Bacterial endocarditis-Patients with valvular
lesions are at a high risk of developing
endocarditis , so,they should receive
chemoprophylactic agents such as
amoxicillin 2000mg 1hour before any
medical or dental surgical procedure to
prevent bacteraemia.

11. CLAVULANIC ACID-B-LACTAMASE INHIBITOR:-
ISOLATED FROM STREPTOMYCES CLAVULIGERUS. COMPETITIVELY & IRREVERSIBLY INHIBITS B-LACTAMASES PRODUCED BY A WIDE RANGE OF
GRAM+VE & GRAM –VE BACTERIA. IT IS A SUICIDE INHIBITOR
Therapeutic Effects:-
Used along with amoxicillin in otitis media , respiratory & urinary tract infections produced by
S.aureus,,E.coli,,H.influenzae,,and gonococci
Used with tazobactam in severe infections caused by B-lactamase producing strains of gram negative bacilli.
Sulbactam given with ampicillin is a popular oral medication(another B-lactamase inhibitor)against strains of
s.aureus

12. CEPHALOSPORINS
 Cephalosporins are obtained from a fungus, cephalosporium acremonium. These are B-lactam antibiotics
with 7-aminocephalosporanic acid nucleus . Mechanism of action are similar to that of penicillins.
 Given either orally or parenterally , excreted via tubular secretion.

13. DRUGS FIRST GENERATION
(Cephalexin)
SECOND
GENERATION
(Cefaclor)
THIRD GENERATION
(Cefixime)
FOURTH GENERATION
(Cefepime)
Antibacterial spectrum
• Gram positive organisms
except enterococci
• Gram negative organisms
E.coli,proteus, H.influenzae
• Anaerobes
• Pseudomonas
• Salmonella
┼┼┼
┼
Effective
Not effective
Not effective
┼┼
┼┼
Effective
Not effective
Not effective
┼
┼┼┼
Effective
Effective
Effective
┼
┼┼┼
Not effective
Effective
Uses Skin and soft tissue
infections due to
streptococci and
staphylococcus aureus
Respiratory tract
infections,sinusitis
• Community acquired
pneumonia
• Gonorrhoea-
Ceftriaxone is given
250mg i.m. as a single
dose
• Typhoid-Ceftriaxone is
given in salmonella
infections
They are reserved drugs
for hospital acquired
resistant infections

14. AMINOGLYCOSIDES
They include streptomycin, gentamycin, kanamycin, neomycin etc.
MECHANISM OF ACTION :-
MECHANISM OF BACTERIAL RESISTANCE:-
Bacterial resistance to aminoglycosides
is due to-
1. Inactivation of drug by the bacterial
enzyme.
2.Decreased entry of drug into bacterial
cell
3.Decreased affinity of the drugs for the
ribosomes
Dosage:-
 Once daily dosing regimen-given as a single
injection
 Multiple daily dosing regimen-given as two or three
equally divided doses

15. USES:-
 Severe aerobic gram negative bacillary infections due to E.coli, Klebsiella, Proteus, Enterobacter
 Tuberculosis- Effective against tubercle bacilli.
 Bcaterial endocarditis
 Other gram negative infections like plague, brucellosis
ADVERSE EFFECTS:-
 Ototoxicity-vestibular and cochlear dysfunctions can occur due to VIIIth
cranial nerve damage. Aminoglycosides get concentrated in the perilymph
and endolymph of the inner ear which can lead to progressive damage to
vestibular and cochlear hair cells. Manifestations are deafness, headache,
dizziness, nausea, vomiting etc.
 Nephrotoxicity-It get concentrated in renal cortex and produces
nephrotoxicity.
 Neuromuscular blocking effect-Apnoea and muscular paralysis have been
reported. They inhibit release of acetylcholine from motor nerve.
 Hypersensitivity reactions-skin rashes, fever, eosinophilia can occur.

16. BROAD SPECTRUM ANTIBIOTICS
TETRACYCLINES
Tetracyclines are compounds with four cyclic rings . They are considered as broad spectrum antibiotics which act by
inhibiting bacterial protein synthesis.Eg:- Doxycycline, Minocycline and can be administered as oral, i.v and topical
routes.
They are called broad spectrum as:-
They are effective against a wide range of microorgranisms, such as-
• Gram positive and gram negative cocci-S.aureus, S.pneumoneae, N.gonorrhoeae
• Gram negative bacilli- V.cholera, H.influenzae, H.pylori
• Gram positive bacilli- B.anthracis, clostridia
• Others- Mycoplasma, chlamydia, actinomyces, spirochetes

17. MECHANISM OF ACTION
Actively taken up by susceptible bacteriaTetracyclines Bind reversibly to 30S ribosome subunit
Prevent binding of aminoacyl tRNA to
mRNA ribosome complex
Prevent the addition of amino
acid to the growing peptide chain
Inhibit bacterial protein
synthesis
RESISTANCE :-
Bacterial reistance to tetracycline is due to:
1.Decreased influx or increased efflux of tetracyclines
2.Inactivation of the drug by enzymes

18. Therapeutic Uses:-
First choice drugs for treatment of rickettsial infections-doxycycline 100mg b.d. is given orally or intravenously for 5-7
days.
Doxycycline used to shorten duration of illness in pneumonia.
Cholera-Single dose of tetracycline or doxycline 300mg is effective
Low doses of Doxycycline are used in Acne.
Highly effective in plague.
Adverse Effects:-
oTetracyclines have calcium chelating property, forming tetracycline-calcium orthophosphate complex, which is deposited in
growing bones and teeth. Increased incidence of caries is seen in these teeth.
oHypersensitivity reactions.
oSuperinfection-It occurs with organisms like Candida,Proteus,Pseudomonas.Characterized by severe diarrhea,fever,abdominal pain
and treated with metronidazole.
oRenal toxicity produced by Demeclocycline is a major concern.it produce diabetes insipidus by blocking the action of ADH on
collecting duct.
oPhototoxicity- Mainly seen with doxycycline, may produce sun burn like reaction and pigmentation also.
oHepatotoxicity-Acute hepatic necrosis with fatty changes are more common.

19. MACROLIDES
Erthromycin is the prototype drug, which was obtained from Streptomyces erythreus and second choice of drugs for
patients with allergy in penicillin.
• MECHANISM OF ACTION:-
They bind to the bacterial 50s ribosomal subunit and inhibit protein synthesis. They are bacteriostatic, but at high
concentrations can act as a bactericidal agent also.
• DOSAGE:-
250-500 mg oral QID(quarter in die i.e 4times a day) for 7days
• ANTIBACTERIAL SPECTRUM:-
Includes mostly gram positive and few gram negative bacteria such as S pyogens, S. pneumoniae, N. gonorrhoea,
C. diptheriae

20. USES:-
 EFFECTIVE AGAINST MYCOBACTERIUM AVIUM COMPLEX, MYCOBACTERIUM LEPRAE,
HELICOBACTER PYLORI
 EFFECTIVE AGAINST H.INFLUENZAE, SALMONELLA, MALARIA ETC.
 WHOOPING COUGH- A 1-2 WEEK DOSE OF ERYTHROMYCIN IS EFFECTIVE FOR ERADICATING
B.PERTUSSIS
ADVERSE EFFECTS:-
 ENTERAL TOXICITY - NAUSEA, VOMITTING , EPIGASTRIC PAIN
 HYPERSENSITIVITY REACTIONS – RASHES , FEVER

21. CHLORAMPHENICOL
It is a broad spectrum antibiotic, was isolated from Streptomyces venezuelae.
MECHANISM OF ACTION:-
chloramphenicol binds reversibly to 50s ribosomal subunit→ prevents the formation of peptide bond
→ inhibits protein synthesis
It is a bacteriostatic agent, but in high concentration can be bactericidal against H.influenzae, S.pneumonia,
N.meningitidis

22. THERAPEUTIC USES:-
 TYPHOID FEVER
 BACTERIAL MENINGITIS-IT CAN BE USED IN COMBINATION WITH AMPICILLIN FOR THE TREATMENT OF MENINGITIS CAUSED BY H.INFLUENZA
,N.MENINGITIDES AND S.PNEUMONAE
 RICKETTSIAL INFECTIONS
 EYE AND EAR INFECTIONS
 BRUCELLOSIS
ADVERSE EFFECTS:-
 Hypersensitivity reactions-Skin rashes, drug fever, allergy
 Bone marrow suppression-2 ways,,1)dose dependent reversible Suppresion of bone marrow, manifested as anaemia,
leukopaenia and Thrombocytopaenia. 2)non dose dependent aplastic anaemia
 Gastrointestinal effects-nausea,vomiting,diarrhoea.
 Gray baby syndrome-In neonates, Chloramphenicol can cause reduced degradation and detoxification of the drug
in liver because of deficiency of glucoronyl transferase enzyme, manifestations are:
Nausea, vomiting, abdominal distension, diarrhoea, cyanosis, irritability and circulatory collapse
Gray baby syndrome

23. SULPHONAMIDES
Sulphonamides are the first antimicrobial agents effectively used in bacterial infection treatment in man . Well
absorbed & evenly distributed and metabolized in liver , acetylated products retain the toxic effect.
Sulphamethoxazole is the most widely used antibiotic.
Mechanism of action:- Acts by destroying the precursor of folic acid essential for growth & multiplication of
organisms.

24. LIST OF SULPHONAMIDES AND PHARMACOKINETICS
PHARMACOKINETICS:-
All sulphonamides are well absorbed
from the gut. They are bound to plasma
proteins, particularly albumin.
These are distributed in almost all
tissues of the body including CSF. They
cross placental barrier and reach
Fetal circulation, metabolized in liver
mainly by acetylation. Excreted partly
unchanged and partly as metabolic
products.

25. Sulphonamides are primarily bacteriostatic against many gram positive
and gram negative bacteria. However bactericidal concentrations may be
attained in urine.
Many Sterptococcus pyogens, Haemophilus influenzae,,Vibrio cholrae.
Only a few Staph. Aureus, gonococci, meningococci, pneumococci,
Escherichia coli and Shigella respond…….Anaerobic bacteria are not
susceptible.

26. Adverse Effects:-
oUrinary tract obstruction , hematuria .
oHypersensitivity reactions-Stevens- Johnson syndrome(most severe hypersensitivity reaction characterized by
fever,erythema multiforme and ulceration of mucous membranes.
oKernicterus-use of sulphonamides in neonates may cause displacement of bilirubin from plasma proteins.the free
bilirubin can cross blood brain barrier and get deposited resulting in kernicterus(it is a hyperbilirubinemic condition in
which the bilirubin accumulate in the gray matter of the central nervous system causing irreversible neurological
damage.)
Uses:-
Treatment of chloroquine resistant malaria
Nocardiosis(an infectious disease affecting either the lungs or the whole body due to the infection by bacterium of the
genus Nocardia,commonly Nocardia asteroides.)
Combined with other drugs to prevent infection of burn wound
Prophylaxis of Rheumatic fever-along with NSAIDS such as aspirin,corticosteroids sulphonamides are also used.

27. COTRIMOXAZOLE
IT IS A WHO APPROVED FIXED DOSE COMBINATION OF SULPHAMETHOXAZOLE AND TRIMETHOPRIM IN THE RATIO OF 5:1
MECHANISM OF ACTION:-

28. ANTIBACTERIAL SPECTRUM
 Antibacterial spectra of trimethoprim and sulphonamides overlap .
 Additional organisms covered by the combination are-----
Salmonella typhi, Serratia klebsiella , Enterobacter,Yersinia enterocoliticia ,Staph.aureus,Strep.
Pyogens, Shigella, E.coli,
H. influenza,Gonococci and meningococci are also covered.

29. PREPARATIONS OF COTRIMOXAZOLE
STRENGTH OF COTRIMOXAZOLE PREPARATIONS
Sulphamethoxazole 400mg+Trimethoprim 80mg Oral, i.v.
Sulphamethoxazole 800mg+Trimethoprim 160mg Double strength,oral,i.m.
Sulphamethoxazole 200mg+Trimethoprim 40mg Oral suspension
Sulphamethoxazole 100mg+Trimethoprim 20 mg Pediatric tablet

30. USES:-
 Urinary tract infection-single dose of cotrimoxazole with 4tablets has been recommended for acute cystitis.Course of 3 to 10 days have
been recommended for lower and upper UTI
 Typhoid fever-Initially cotrimoxazole was effective alternative to chloramphenicol.but,resistant S.typhi have appeared,so now it is
seldom used.Strains of S.typhi respond to 1 tab BD for 2weeks…
 Nocardiosis
 Bacterial diarrhoeas-It can be used for severe and invasive infections by Campylobacter,,E.coli,,
Shigella,,andY.enterocolitica
 Bacterial respiratory tract infections-Both upper and lower respiratory tract infections caused by gram positive cocci and H.influenzae
respond well.
ADVERSE EFFECTS:-
 GI disturbances
 Megaloblastic anaemia

31. QUINOLONES
Effective against gram-negative bacteria including E.coli , Proteus , Kleibsella, Shigella, etc excepting Pseudomonas.
Nalidixic acid interferes with the replication of bacterial DNA. Eg: Norfloxacin, Ciprofloxacin, Levofloxacin etc.

32. Route of administration:-
These drugs can be given by oral, topical and as i.v. infusion
Uses:-
Urinary tract infections-E.coli, staphylococcus ,saprophyticus infections are treated.
Bacterial diarrhoeas
Typhoid fever-A dose of 500 to 750 mg BD for 10 days is recommended. Patients unable to take drug orally is treated
with 20mg i.v 12 hourly in the beginning.
STD’s such as gonococcal infections & chancroid formation treated by ciprofloxacin-500 mg BD for 3days is an
excellent alternative to erythromycin
Urethritis, meningitis, conjunctivitis
Adverse effects:-
•Vomiting , nausea and other GI tract irritations are common.
•CNS effects-headache , dizziness, insomnia.
•Moxifloxacin causes prolongation of QT interval.
•Contraindicated in pregnancy.
•Cartilage damage ; should be avoided in young children.

33. CARBAPENEMS
It is a semisynthetic βLactam antibiotic. It acts by producing bactericidal activities. Mainly effective against gram
positive organisms like streptococci, staphylococcci, enterococci etc. Eg:-Imipenem
Can be administered through i.v. route.
MONOBACTAMS
It is also a βlactam antibiotic with only one ring in it's structure, hence the name. It also has bactericidal activity.
It is effective only against gram negative bacteria such as enterobacteriaceae. For eg:- Aztreonam.
Administered only parenterally.

34. ANTIBIOTIC PROPHYLAXIS IN DENTISTRY

36. Prophylaxis of Surgical site Infection:-
Includes superficial incisional infections(stitch abscess),deep incisional infections , organ space infection
Classification of operative wounds and their treatment(as per NRC criteria):-
Clean
Clean contaminated
Contaminated
Dirty
Dirty contaminated(including road side accidents)
Usually Cefazolin 1 g i.v 8 hourly + Vancomycin 1 g i.v 12 hourly is given . For severe cases 5 day regimen
recommended involving Ampicillin , Metronidazole & gentamycin given 8 hourly i.v.
Pathological Conditions in oral cavity:-
Leukoplakia treatment- Amphotericin B
Systemic Candidiasis- Polyene
Oral Manifestations of tuberculosis- Rifampicin
Leukoplakia in tongue

37. PROBLEMS WITH ANTIBIOTIC THERAPY
Unfortunately , irrational use of antibiotics often lead to severe problems , such as:
1)Toxicity-May be systemic or local irritancy , as discussed earlier in cases of penicillin & noted in
tetracycline
2)Hypersensitivity reactions
3)Drug Resistance in the form of either natural or acquired by gene transfer
4)Development of cross resistance
5)Superinfection as a result of the therapy
6)Nutritional deficiencies such as B-complex Vitamin deficiencies are common
7)Antibiotics may mask an infection, thereby not really curing it.for eg: Streptomycin short course in
tuberculosis.
Drug induced Oral Candidiasis

38. REASONS FOR FAILURE OF ANTIBIOTIC THERAPY
•INAPPROPRIATE CHOICE OF ANTIBIOTICS
•PATIENT FAILURE TO TAKE ANTIBIOTICS
•IMPAIRED HOST DEFENCE
•POOR PENETRATION TO INFECTED SITE
•SLOW MICROBIAL GROWTH
•FAILURE TO ERADICATE SOURCE OF INFECTION
•UNFAVOURABLE LOCAL FACTORS
•LIMITED VASCULARITY
•PRESENCE OF RESISTANT MICRO-ORGANISMS