Antibiotics

ANTIBIOTICS IN ORAL AND MAXILLOFACIAL SURGERY

AIM: The aim of this seminar is to discuss various antibiotics and their use in

oral and maxillofacial surgery.

INTRODUCTION: Antibiotics are regarded as miracle drugs. They are our

most effective weapons against infectious diseases brought about by

microorganisms like bacteria, fungi and parasites. In the past treating the

bacterial infections was very difficult. In fact before the discovery of

antibiotics, many patients contracting bacterial infections never made it out of

hospital beds alive. This is why discovery of antibiotics was one of the most

important health advances in human history. Antibiotics have a well

documented efficacy in the trearment of established infections and as

prophylactic agents in medically compromised patients.

DEFINITION: Antibiotic is a chemical substance produced from microorganisms

have the property of inhibiting the growth of other microorganismsin high

dilution.

HISTORY: PAUL ERHLICH(1854-1915) an organic chemist observed that

methylene blue specifically killed and stained certain bacterial cells and

reasoned that chemical might be produced that could unite with and destroy

parasitic agents of disease without injuring the host cells. First accidentally

discovered in 1928 by ALEXANDER FLEMING when a dish in which he was

growing staphylococcus bacteria became contaminated with pencillium mould

was destroying bacteria. This substance was later named PENICILLIN. In 1944

WALKSMAN isolated streptomycin from streptomyces griseus in culture from

chicken throat.

MODE OF ACTION: Antibiotics act on four targets

1. Cell wall

2. Cytoplasmic membrane

3. Ribosomes

4. RNA molecules involved in transcription of genetic information.

CLASSIFICATION:

Antibiotics are broadly classified in to

Bactericidal antibiotics- they kill bacteria

Bacteriostatic antibiotics- they inhibit bacterial proliferation.

Based on their mechanism of action antibiotics are classified as

I) Inhibit cell wall synthesis: penicillins, cephalosporins, vancomycin,

bacitracin, cycloserine.

II) Damage of cell membrane causing leakage of cell contents:

polymixins, amphoterecin B, nystatin.

III) Bind to ribosomes and inhibit protein synthesis: chloramphenicol,

tetracyclines, erythromycin, clindamycin, aminoglycosides.

IV) Inhibit DNA gyrase: fluoroquinolones.

V) Inhibit DNA function: rifampicin.

VI) Inhibit DNA synthesis: acyclovir, zidovudine.

VII) Interefere with metabolism: sulfonamides, trimethoprim.

ANTIBIOTICS ANTIBACTERIAL SPECTRUM

DOSE ROUTE OF ADMINISTRATION

Fluoroquinolones Gram negative and gram positive and anaerobic organisms.

1) Norfloxacin 400mg BD

Oral

2) Ciprofloxacin 250-750mg BD

Oral

3) Pefloxacin 400mg BD 400mg 12hrly

Oral IV

4) Ofloxacin 200-400mg OD 200-

Oral IV

400mg 12-24 hrly

5) Lomyfloxacin 400mg OD

Oral

6) Sparfloxacin 200-400mg OD

Oral

ANTIBIOTICS ANTI BACTERIAL SPECTRUM

DOSE ROUTE OF ADMINISTRATION

Penicillins Narrow antibiotic spectrum effective against gram positive organisms

1) Sodium penicillin G 0.5-5MU 4-6hrs

IV/IM

2) Procaine penicillin G

0.5-1MU 12-24 hrs

IM

3) Benzathine penicillin G

1.2-2.4 MU 3-4 WKS

DEEP IM

SEMISYNTHETIC PENICILLINS

1) Dicloxacillin 200-500mg QID

Oral

2) Naficillin 1-2 gms 4-6hrs

IV

3) Ampicillin 250mg or 1 gm qid

Oral

4) Ampicillin and salbactum

1gm and 0.5gm 6-8hrly

IV

5) Amoxicillin 250-500mg tid

Oral

6) Amoxicillin and clauvlanic acid

250mg and 125 mg tid

Oral

7) Piperacillin 3-4 gms 4-6hrly

IV

8) Ticarcillin 3gms 4-6hrly

IV

CEPHALOSPORINS First generation Have wider

activity than penicillin. Gram positive resistent to penicillin

1) Cephalothin 1-2gms 6hrly

IV

2) Cephalozin 0.5-1gm 6hrly

IM/IV

3) Cephalexin 0.25-1gm qid

Oral

4) Cefadroxil 0.5-1gm bid

Oral

Second generation Gram negative resistent to beta lactamases

1) Cefuroxime 0.75-1.5gm 8hrly

IM/IV

2) Cefumandole 0.5 -2gms 4-8 hrly

IM/IV

3) Cefuroxime 0.25-0.5gm bd

Oral

4) Cefaclor 0.25-0.5gm

Oral

Third generation Highly resistent to beta lactamases. Effective against gram

negative organisms

1) Cefotaxime 1-2gms 8hrly

IM/IV

2) Ceftriaxone 1-2gms od

IM/IV

3) Cefperazone 1-2gms 8-12hrly

IM/IV

Fourth generation Serious gram negative infections

1) Cefipime 1-2gms 12hrly

IV

Broad spectrum antibiotics

TETRACYCLINES Gram positive, gram negative, rikketsciae, chlamydiae, mycoplasma

1) Chlortetracycline 250-500mgs qid

Oral

2) Tetracycline 250-500mgs qid

Oral

3) Doxycycline 200mgs initially then 100mgs od

Oral

4) Minocycline 200mgs initially then 100mgs od

Oral

Chloramphenicol Gram negative, gram positive, anaerobic bacteria,

chlamydiae, mycoplasma

AMINOGLYCOSIDES Gram negative anaerobic bacilli

1) Streptomycin 1-2gms/day

IM

2) Gentamycin 3-5mg/kg in three divided doses

IM/IV

3) Tobramycin 3-5mg/kg in three divided doses

IM/IV

4) Amikacin 15mg/kg in 2-3 divided doses

IM/IV

5) Netilmycin 4-6mg/kg in 2-3 divided doses

IM/IV

MACROLIDES Erythromycin Narrow

spectrum, gram positive and few gram negative organisms

1) Erythromycin stearate

250-500mgs qid 7-14 days

Oral

2) Erythromycin estolate

250-500mgs qid 7-14 days

Oral

3) Roxitromycin 150mgs Oral 4) Azitromycin 500mgs

then 250mgs od next three days

Adverse effects

1. Fluoroquinolones:--

Tendinitis with assosciated risk of tendon rupture.they damage

growing cartilage resulting in anthrppathy . Hence contraindicated up to

18 years of age.

2. Pencillin:--

(i) Hypersensitivity reactions ranging from skin

rashes,urticaria,fever,bronchospsm,serum rickness and rarely exfoliature

dermatitis and anaphylaxis.

(ii) Jarish-herxheimex reaction -when pencillin is injected in a patient

with syphilis,there is sudden destruction of spirochetes and release of its

tylio products which triggers a reaction with fever,myalgia,shivering.

3. Cephalosporins :-- 20% patients allergic to pencillon show reactivity to

cephalosporins

4. Tetracyclines:--

hepatoloxity,renal toxity,phototoxity.

out dated tetracyclines cause fanconils

syndrome.(vomting,polyuria,protienuria,glycosuria)

effect on teeth and bones:--tetracyclines chelate calicium.the

calicium tetracycline orthophosphate complexes yet deposited in

developing teeth and bones .he deormites depend on time of

tetracycline administration.

Period structures affected

deformity

mild pregnancy to 5 months of dicicluous teeth

broconish discolouration,ill portnatal

formed,more caries

suseptible

2months to 5 years of age perment teeth

pigmentation,discolouration

pregnancy and childhood up to 8 skeleton

depressed bone growth

Chloramphenicol:--

Gray baby syndrome:-- new born babies may develop vomting,

hypotension, hyperthermia and ashen gray cyanosis asthey cannot

metabolise and excret chloramphenicol.

Inoglyclorids:-- Ootoloxity,nephrotoxity

Erthromycin:--

Inhibits hepatic metabolism and rises plasma levels of

carbemazepine, terfanidine, valproate,aligoxin and results in their

toxicity.

Roxythromicin , clarithromicin and Azithomyccin do not have any drug

interactions.

Principles for choosing Antibiotics:---

In most clinical situations,it is easy to determine whether a patient

has an infection. Locally, the classical signs and symptoms of

pain,swelling,surface erythema,pus formation and

sustematically,fever,lymphadenopathy,malaise, a toxic appearance and

an elevated white blood cell count are formed.

Infections are ultimately cured by the host and not by antibiotics .

Antibiotic therapy reduces bacterial challenges and allows hort defences

to complete the treatment.

Initial empirical therapy may be instituted with a fair degree of reliability

if the following criteria are met .

(i) Site and features of infection have been well met

(ii) Circumstances leading to infection are well known.

(iii) Organism or organisms that most commonly cause such infections

are well known.

Definitive therapy is done after culture reports are received .

Early infections that present as cellulitis with out abcess formation

are most caused by aerobic bacteria. As the infection becomes

more severe ,the microbiology becomes more severe ,the

microbiology becomes a mixed flora of aerobic and anaerobic

bacteria are no longer able to survive in hypoxic acidic

environment.

Principles:---

1. State of host defences:--

Antibiotics help in situations which the host has been over

whelmed by bacteria or when especially virulent bacteria are

involved .When a patients defences are impaired ,antibiotics,

play a more important role in control of infections.

Eg:-- cancer,leukemias,malnutrition,poosly controlled diabetes.

Cycotoxic drugs and immune supressents like glucocorticoids,

azathioprine, cyclosprin affect host defences.

Aggressive antibiotic therapy must be considered in treating

established infections in patients in any of these categories .

Surgicaldrainage and incision may also deviate the use of an

antibiotic or may increase the effectiveness of an antibiotic as

vascular flow is restored.

Determination of Antibiotic sensitivity:--

Staphy lococcus infection must be treated with antibiotic

susceptibility information in hand.Pencillin G can be used only

if sensitivity studies support its effectiveness.Pencillinnase

resistant pencillins should be used. There is an increasing

incidenceof resistance to pencillinase resistant drugs ,which

currently is high enough to warrant antibiotic routine

susceptibility testing for staphylococcal infection.

PencillinExcellent for treatment of streptococcus infection.

Good to excellent for major odontogenic infectons

Erythromycineffective against streptococcus ,pepto

streptococcus, preuotella/

Clindamycingood for streptococcus.

CephalexinModerate active against streptococcus,good age

MetronidazoleNo action against Streptococcus.Excellent

activity against anaerobes

Use of narrow spectrum Antibiotic :--

Antibiotic with narrowest anti bacterial spectrum should be

used.

Eg:--If streptococcus is sensitive to pencillin, cephalosporin and

tetracycline . Pencillin should be used because it has narrowest

spectrum.

The other two act against a variety of gram negative organisms and their use

leads to development of resistent organisms.

Use of narrow spectrum antibiotics minimize the risk of super infections

because they allow large proportions of host flora to be maintained.

USE OF LEAST TOXIC ANTIBIOTICS:

Select least toxic drugs from among those that are effective. Eg: bacteria

causing odontogenic infections are sensitive to penicillin and chloramphenicol.

Though chloramphenicol is more effective than penicilin, it is not preferred

because of its potential to cause severe bone marrow depression.

PATIENT DRUG HISTORY:

Two aspects should be reviewed in drug history

Previous allergic reactions

Previous toxic reactions

Allergy rate to penicillin is approximately 5% so history of previous allergy

should be abtained. It is well documented that co-incident allergies to

cephalosporins and penicilins do exist. So if patient is allergic to penicillin,

cephalosporins should be used unless it is deemed necessary only after

preparations are made to treat severe reactions.

Penicillin allergy: skin testing should be done 24hrs before penicillin

administration. Potential reactions with other drugs, the patient is taking is

considered.

USE OF BACTERICIDAL RATHER THAN BACTERIOSTATIC DRUGS:

Advantages of bactericidal antibiotics:

Less reliance on host resistance

Killing of bacteria by antibiotic itself

Faster results than bacteriostatic drugs

Greater flexibility with dosage intervals

Bactericidal drugs exert their influence after they are incorporated into the

bacterial cells and the cell eventually dies.

Bacteriostatic drugs exert their action only when present in patients tissues so

the bacteria resume their growth after drug is eliminated. So rigorous time

schedule should be followed up.

In immunocompromised patients bactericidal drugs are preferred to

bacteriostatic drugs.

Cotrimoxazole, fluoroquinolones, penicillins, cephalosporins, aminoglycosides,

vancomycin, teicoplanin are bactericidal.

Sulfonamides, tetracyclines, chloramphenicol are bacteriostatic.

Erythromycin is bacteriostatic in low doses and bactericidal in higher doses.

USE OF ANTIBIOTICS WITH A PROVEN HISTORY OF SUCCESS:

The best evaluation of the efficacy of a drug in a particular situation is the

critical observation of its clinical effectiveness over a prolonged period.

Standard drug should not be disapproved for an unapproved drug without

good reason. The newer drug should be effective for bacteria against which no

other antibiotic is effective.

Eg. Methicillin for penicillinase.

Such drugs should be used only for those bacteria with proven sensitivity.

We can select a new antibiotic if it is less expensive, more potent, less toxic,

few side effects than older one but should be used with caution.

COST OF ANTIBIOTIC:

Reasonably affordable price should be considered.

PRINCIPLES OF ANTIBIOTIC ADMINISTRATION:

Antibiotic must be administered properly. This involves consideration of

dosage, route of administration and combination therapy.

PROPER DOSE:

Any drug should be administered in sufficient amounts to achieve deserved

therapeutic effect but should not cause injury to host. Minimum inhibitory

concentration of an antibiotic for a specific bacteria should be calculated. For

therapeutic purposes, the peak concentration of antibiotics at the site of

injection should be 3-4 times the minimum inhibitory concentration. Dose

above this level does not improve the therapeutic results but will cause

toxicity. Eg. Gentamicin is effective in concentrations up to 4-6 microgram/ml

but the incidence of nephrotoxicity increases dramatically at 10 microgram/dl

plasma level.

In cases of infections isolated from blood supply, increased antibiotic doses can

be given. The high plasma concentration can cause greater amount of

antibiotic to reach the sealed of bacteria by simple diffusion.

Sub therapeutic doses should not be given as they supress clinical

manifestation without actually killing microbes and hence may result in

recurrence of infection after discontinuation of drug.

PROPER TIME INTERVAL:

The usual dosage interval for the therapeutic use of antibiotic is four times the

t1/2. At five times t1/2 95% of drug is excreted.

Eg. T1/2 of cefazolin is 2hrs . so interval between doses should be 8hrs.

In patients with compromised renal function, prolonged interval should be

given because excessive plasma levels due to decreased clearance would cause

toxicity.

ROUTE OF ADMINISTRATION:

Some times only parenteral route of administration would provide adequate

serum level of antibiotic. If given orally, should be given 30mins before or 2 hrs

after meals for maximum absorption.

When long term parenteral administration is necessary IV is preferred over IM

as IM is poorly accepted by patient.

CONSISTENCY IN ROUTE OF ADMINISTRATION:

In case of serious infections parenteral route is preferred. After initial response

we usually switch to oral administration. But this may cause recurrence of

infection as blood levels of drug are lower when we switch to oral route on

second or third day of therapy. After 5 days oral levels are sufficient.

“Maintenance of peak blood levels of antibiotics for adequate period is

important to achieve maximum tissue penetration and effective bacterial

killing.” In case of mild infection oral administration is sufficient.

COMBINATION ANTIBIOTIC THERAPY:

Combination antibiotic therapy should be avoided for routine infections as it

may provide broad spectrum exposure leading to emergence of resistent

bacteria.

Indications of combination therapy:

When it is necessary to increase the antibacterial spectrum in patients

with life threatening sepsis of unknown cause.

When increased bactericidal effect against a specific organism is

desired.

To prevent rapid emergence of resisrent bacteria. Eg: treatment of

tuberculosis by multiple drugs.

In emperic treatment of certain odontogenic infections. Eg: severe

cellulitis type of infections rapidly progressing posteriorly around the

lateral and retropharyngeal spaces, bactericidal activity against

streptococcus and oral anaerobes is important. As prevotella is

resistent to penicillin, both parenteral penicillin and metronidazole

should be given to provide bactericidal activity against both

streptococcus and anaerobes.

Patient monitoring : patient should be monitered for response to

treatment and development of alveolar reactions.

Response to treatment: no response to antibiotics occurs in 24-48 hrs.

Action begins after second after second day.

Objective signs and symptoms are decreased temperature, swelling

pain.

Eradication of infection is reached by third day with decrease of

symptoms. In case of uncomplicated odontogenic infections

improvement begins on second day of therapy and marked resolution

is seen by third day and an additional two days is needed to resolve

the infection. In case of severe infection, seven day course is needed.

If patients condition does not improve after initial therapy, antibiotic

should not be changed immediately as it takes some time and

following clarifications should be done.

1. Carefully evaluate the patient

2. Look for need for additional surgery to drain pus or

release pressure or remove foreign body.

3. Other possible sites of infection should be evaluated

4. Portals of entry such as IV catheter should be checked

5. Adequate hydration and nutritional support are

necessary.

If initial therapy failed the following clarifications should be made

1. Is the route of administration adequate to deliver effective dose of drug

2. Is patient taking antibiotic prescribed

3. Are physcians order followed

4. Is choice of antibiotic correct

If initial therapy failed culture should be done before changing the drug. A

second empirical choice should be avoided due to low success rate.

Development of adverse reactions:

Adverse reactions may be in the form of anaphylactic reaction or less severe

reaction associated with edema urticaria and itching or there may be delayed

reaction presenting only as a low grade temperature. Patient should be

cautioned about allergy. If allergic reaction occurs it should be treated and

patient should be informed about the drug used and type of reaction and

should be advised caution in future.

ANTIBIOTIC ASSOCIATED COLLITIS:

It is a toxic reaction. It was originally associated with clindamycin but noe

ampicillin, amoxicillin and cephalosporins are also found responsible.

Clinical features: watery diarrhoea, creamping abdominal pain, fever.

Treatment: Discontinue causative antibiotic. Restore fluid and electrolyte

balance. Administer clostridial antibiotics., vancomycin and metronidazole can

be used.

SUPER INFECTION AND RECURRENT INFECTION:

In normal state, normal flora acts as a defence mechanism, but when this

mechanism is altered or eliminated due to use of antibiotics superinfection

occurs. Eg: candida infection due to long term treatment with penicillins as in

actinomycosis and osteomyelitis.

In case of osteomyelitis and actinomycosis more carefull and longer follow up

is necessary as the nonvital bone provides a barrier to antibiotic effectiveness

and is a potential focus of re-infection. In such cases, re institution of

antibiotics should be done with additional surgical intervention if necessary.

THERAPEUTIC USES OF ANTIBIOTICS IN ORAL AND MAXILLOFACIAL SURGERY:

ABSCESS: Penicillin is the drug of choice. Adjunctive treatment like endodontic

treatment, extraction of tooth or surgical drainage should be done.

PERICORONITIS: Anaerobic bacteria including gram positive cocci and gram

negative rods are obtained on culture. Penicillin is the drug of choice.

ODONTOGENIC INFECTIONS AND DEEP FASCIAL SPACE INFECTIONS OF

DENTAL ORIGIN: Well localized and easily drained dentoalveolar abscess can

be treated by surgical drainage. Antibiotic therapy is needed in case of

Poorly localized, extensive abscess associated with diffuse

cellulitis.

Abscess in case of immunocompromised patients, patients with

poorly controlled diabetes and patients on renal dialysis.

Majority of infections consists of mixed aerobic and anaerobic flora. According

to MOENING(1989) “it would seem presumptuous to state that penicillin is

currently not effective against most odontogenic infections and premature to

consider substituting another antibiotic as the drug of chioce for mild to

moderate odontogenic infection especially when low cost and lack of toxicity is

considered.”

In case of more severe infections antibiotic sensitivity tests may be needed.

Metronidazole is effective supplement to penicillin as it acts against

anaerobes. Erythromycin is poorly absorbed and is less effective in case of

odontogenic infections. Azithromycin is better tolerated than erythromycin. In

case of very severe infections combination of amoxicillin and clavulanic acid is

preferred. First and second generation cephalosporins are used. Tetracyclines

are not recommended. Minocycline and doxycycline can be used for low grade

odontogenic infections. Patients requiring hospitalization for odontogenic

infections and for immunocompromised host, the treatment regimen is

CLINDAMYCIN alone (or)

CLINDAMYCIN+METRONIDAZOLE

(or)

GENTAMICIN

(or)

PARENTERAL AMPICILLIN+SULBACTUM

OSTEOMYELITIS: causative organisms are staphylococcus epidermis, hemolytic

streptococci, prevotella, porphyromonas. Most of these organisms are

penicillin resistent so metronidazole is effective.

ANTIBIOTIC REGIMEN FOR OSTEOMYELITIS OF JAWS:

Regimine 1: for hospitalized /medically compromised patient or when IV

therapy is indicated.

1) Aq penicillin 2 million units IV 4 hrly , metronidazole 500mg 6 hrly

When improved for 48-72hrs, switch to penicillin V 500mg per oral 4 hrly

plus metronidazole 500mg per oral 6 hrly for an additional 4-6 weeks.

Ampicillin/sulbactum 1.5 -3 gms IV 6hrly, when improved for 48-72 hrs

switch to amoxicillin/clavunate 875/125 mg per oral bid for an addditional

4-6 weeks.

Regimen 2: for out patient treatment

PenicillinV 2gm plus metronidazole 0.5 gm 8hrly per oral for 2-4 weeks

after last sequestrum removed and patient without symptoms.

Clindamycin 600-900mg 6hrly IV then clindamycin 300-450mg 6hrly per oral.

Cefoxitin 1.0 gm 8hrly IV or 2gm 4hrly IM or IV untill no symptoms, then switch

to cephalexin 500mg 6hrly per oral for 2-4 days.

For penicillin allergic patients, clindamycin and cefoxitin can be given.

Cephalosporins are not first choice in the management of osteomyelitis

because they are only moderately effective against oral anaerobes and their

broad spectrum coverage increase antibiotic complications.

Erythromycin and other macrolides like clarithromycin, azithromycin, are not

recommended for treatment of osteomyelitis because they are no longer

reliably effective against the oral streptococci and anaerobes.

CHRONIC SUPPURATIVE OSTEOMYELITIS:

Usually requires surgical procedures such as sequestrectomy and removal of

foreign bodies such as wires, bone plates etc. Treatment should begin with IV

therapy and continue even after discharge using home IV therapy usually with

ampicillin/salbactum sodium because it is stable for 24hrs after mixing with IV

fluids.

IV therapy for 2 weeks or untill the patient has shown improvement for 48-72

hrs. Oral therapy should be continued for 4-6 weeks after patient has no

symptoms or from the date of last debridement.

If ampicillin/sulbactum sodium is ineffective clindamycin therapy is indicated.

Antibiotic impregnated beads deliver higher concentration of antibiotic into

wound bed and in immediate proximity to infected bone as antibiotic is

leached out from beads, thus low systemic toxicity. These are useful for

chronically infected bone associated with fracture and in chronic sclerosing

osteomyelitis refractory to systemic antibiotics. eg.tobramycin or gentamicin in

acrylic resin bone cement beads. They are removed after 10-14 days.

SALIVARY GLAND INFECTIONS:

Empirical therapy:

Out patient- amoxicillin+clavulanic acid

In patient- ampicillin+sulbactum(parenteral)

In case of penicillin allergy clindamycin is used. Erythromycin is not indicated

due to high bacterial resistance. Azithromycin and clarithromycin can be used

in out patient community acquired acute bacterial parotitis. Antibiotic therapy

should be continued untill atleast 1 week after resolution of signs and

symptoms.

ANTIBIOTIC PROPHYLAXIS IN HEAD AND NECK SURGERY:

Antibiotic prophylaxis in oral and maxillofacial surgery aims the prevention of

infection of the surgical wound, either due to characteristics of surgery or the

general state of the patient. Prophylactic antibiotic therapy creates an area of

resistance to microorganisms by means of antibiotic serum concentrations that

may avoid the multiplication and spread of bacteria through the surgical injury.

ADVANTAGES:

Decreased patient infection

Decreased post operative morbidity

Decreased cost of health care

Decreased amount of antibiotics used.

DISADVANTAGES:

They may alter host flora

Sometimes when the risk of infection is low, antibiotics donot have

effect.

PRINCIPLES:

1.RISK OF INFECTION MUST BE SIGNIFICANT:

a) Bacterial innoculum should be sufficient size to cause infection.

b) Prolonged and extensive surgery.

c)Presence of foriegn body

d) Depressed host defences

2.CHOOSE CORRECT ANTIBIOTIC:

a) Antibiotic must be effective against causative organism.

b) Choose narrow spectrum antibiotic

c) It should be least toxic

d) Select bactericidal antibiotic

3.ANTIBIOTIC PLASMA LEVELS MUST BE HIGH:

a) Prophylactic doses should be higher than therapeutic doses

b) Antibiotic should diffuse into all fluids and tissue spaces where surgery

is going on.

c) Doses should be atleast two times the therapeutic dose.

Eg:penicillin-1gm

Cephalosporins-1gm

Clindamycin-300mg

Clarithromycin-500mg

4.ANTIBIOTIC MUST BE TIMED CORRECTLY:

For maximum benefit ,antibiotic should be given before surgery begins.

If the surgery is prolonged and intra operative dose is required,intervels

should be shorter(half the usual therapeutic dose interval).This will ensure

that the peak plasma levels are maintained and avoids periods of inadequate

antibiotic levels in tissue fluids.

Eg: penicillin should be given every 2 hrs.

Cephalexin should be given every 2 hrs

Clindamycin should be given every 3 hrs

5.USE SHORTEST ANTIBIOTIC EXPOSURE THAT IS EFECTIVE:

No additional antibiotic is neede after surgery. Final dose of antibiotic

should be given at the termination of surgery.

ANTIBIOTIC PROPHYLAXIS OF WOUND INFECTION:

1.PARENTERAL REGIMEN:

1. Penicillin:

Preoperative 1 million units IV

Intraoperative 1 million units IV q2hrs

Post operative 1 million units IV in recovery room

2.Cephazolin(penicillin allergic patients)

Preoperatively 1gm IV

Intraoperatively 1gm Ivq 4h

Postoperatively 1gm IV in recovery room.

3.Clindamycin

Preoperatively 600mg IV

Intraoperatively 600mg IV 4h

Post operatively 600mg IV in recovery room

2.ORAL REGIMEN:

1.Penicillin

Preoperative 2mg po 30min before

Intraoperative 1mg per oral 2hrly

Post operative 1mg per oral 2hrly

2. erythromycin

Preoperative 1gm 1hr before

Intraoperative 500mg per oral 2hrs

Post operative 500mg peroral 2hrs

PROPHYLAXIS FOR SUBACUTE BACTERIAL ENDOCARDITIS:

Parenteral-oral combined regimen:

1. Preoperatively 30-60 mins

Aqueous penicilinG – 1million units IM

Procaine penicillinG – 6,00,000 units IM

2. Post operatively 8 doses

PenicillinV 500mg peroral 6hrly.

Children:

Preoperatively 30-60mins

Aqueous penicillinG- 30,000 units/kg IM

Procaine penicillinG- 6,00,000 units IM.

Post operatively 8doses

a) PenicillinV

I) Less than 27kg(60lb) 250mg peroral 6hrly

II) More than 27kg(60lb)500mg peroral 6hrly

Oral regimen:

ADULTS:

1. Preoperatively 30-60 mins

penicilinV –

Procaine penicillinG – 6,00,000 units IM

3. Post operatively 8 doses

PenicillinV 500mg peroral 6hrly.

Children:

Preoperatively 30-60mins

Aqueous penicillinG- 30,000 units/kg IM

Procaine penicillinG- 6,00,000 units IM.

Post operatively 8doses

b) PenicillinV

III) Less than 27kg(60lb) 250mg peroral 6hrly

IV) More than 27kg(60lb)500mg peroral 6hrly

FOR PATIENTS ALLERGIC TO PENICILLIN:

Adults:

Preoperatively ½-2hrs

Erythromycin 1.0gm peroral

Postoperatively 8doses

Erythromycin 500mg peroral 6hrly

Children:

Preoperatively ½-2hrs

Erythromycin 20mg/kg peroral

Postoperatively 8 doses

Erythromycin 10mg/kg peroral 6hrly

ANTIBIOTIC MISUSE:

The misuse and increased use of antibiotics are inducing the rapid growth of

antibiotic resistant bacteria(super bug), making it difficult for clinicians to treat

infections.

PREVENTION:

a) Narrow spectrum antibiotics should be prescribed.

b) Microbiology lab results should be the only factor determining the type

of antibiotic medication prescribed to patients.

c) Patients should be educated regarding misuse and increased use of

antibiotics.

d) Patients should follow prescribed directions.

e) Sale of over the counter antibiotics should be emphasized upon.

ANTIBIOTIC RESISTANCE:

The increase in antibiotic resistant bacteria is largely due to wide spread use of

antibiotics in medicine, animal care and agriculture.

MULTIPLE DRUG RESISTANT ORGANISMS:

Multiple drug resistant organisms are resistant to treatment with several,

often unrelated, antimicrobial agents. Some of the most important types of

multiple drug resistant organisms are

MRSA- methicillin/oxacillin resistant staphylococcus aureus

VRE- Vancomycin resistant enterococci

ESBLs-extended spectrum beta lactamases(which are resistant to

cephalosporins and monobactams)

PRSP-Penicillin resistant streptococcus pneumoniae

MECHANISM OF ANTIBIOTIC RESISTANCE IN BACTERIA:

1) Chloramphenicol- reduced uptake into cell

2) Tetracycline- active efflux from cell

3) Beta lactums,erythromycin, lincomycin- eliminates or reduces binding

of antibiotic to cell target.

4) Beta lactums, aminoglycosides,chloramphenicol- enzymatic cleavage

or modification to inactive antibiotic molecule

5) Sulfonamides, trimethoprim- metabolic bypass of inhibited reaction

PREVENTION:

Search for new antibiotics

Stop the use of antibiotics as growth promoting substances in farm

animals

Use the right antibiotic

Stop unnecessary antibiotic prescription

Finish antibiotic prescription

CONCLUSION:

The discovery of antibiotic was a leap in modern medicine. They have been

able to stop the growth or kill many different kinds of microorganisms.

However, bacteria have proven to be much more innovative and adaptive than

we imagined and have developed resistance to antibiotics at an ever increasing

pace. Bad practices and mismanagement have only exacerbated the situation.

However, with more research education of public and well thought out

regulations, the problems can be solved.