Guideline on Rational Use of Antibiotics

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Rational use of medicines refers to the correct, proper and appropriate use of medicines. Rational use requires that patients receive the appropriate medicine, in the proper dose, for an adequate period of time, and at the lowest cost to them and their community.


GENERAL PRINCIPLES IN THE USE OF ANTIBIOTICS IntroductionAntibiotics are one of the most commonly prescribed drugs today. Rational use of antibiotics is extremely important as injudicious use can adversely affect the patient, cause emergence of antibiotic resistance and increase the cost of health care. Prescribing an antibiotic comprises several phases:i) perception of need - is an antibiotic necessary ? ii) choice of antibiotic - what is the most appropriate antibiotic ? iii) choice of regimen : what dose, route, frequency and duration are needed ? iv) monitoring efficacy : is the treatment effective ?

Is an antibiotic necessary? : 

Is an antibiotic necessary? Antibiotics are generally only useful for the treatment of bacterial infections. It is important to remember that not all fevers are due to infections and not all infections are caused by bacteria. The majority of infections seen in general practice are of viral origin and antibiotics can neither treat viral infections nor prevent secondary bacterial infections in these patients. Even where a bacterial aetiology is established, an antibiotic may not be always necessary. Many bacterial infections resolve spontaneously. Minor superficial skin infections may be more suitably treated with a local antiseptic. Collections of pus should be drained surgically and if drainage is adequate, antibiotics are often not required.

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Even where a bacterial aetiology is established, an antibiotic may not be always necessary. Many bacterial infections resolve spontaneously. Minor superficial skin infections may be more suitably treated with a local antiseptic. Collections of pus should be drained surgically and if drainage is adequate, antibiotics are often not required.



Choice of an antibiotic : 

Choice of an antibiotic The successful outcome of therapy would depend very much on the choice of the antibacterial agent. In the process of selecting an antibiotic, three main factors need to be considered; the aetiological agent, the patient and the antibiotic.

The aetiological agent : 

The aetiological agent Determination of the aetiological agent depends on a combination of clinical acumen and laboratory support. In many instances an antibiotic prescription has to be made based on the clinical diagnosis (empirical therapy). Even where a bacteriology report is available it is necessary to interpret the report. Bacterial isolates from culture specimens may represent normal flora, colonisers or contaminants rather than true pathogens. Sensitivity results when available are at best only a guide to treatment. Laboratory reports should always be viewed in the light of clinical findings.

The patient : 

The patient Several patient factors have to be considered in selecting an antibiotic. Age is an important factor. The very young and the very old tend to be more prone to the adverse effects of the antibiotics. Neonates have immature liver and renal functions which affect their ability to metabolise or excrete antibiotics. Antibiotics and their metabolites may adversely affect growing tissues and organs in children. Elderly patients are more likely to suffer from nephrotoxicity and allergic reactions. Dosage modifications would also have to be made in those patients with hepatic or renal impairment. Antibiotics can also give rise to severe toxic reactions in patients with certain genetic abnormalities Eg : sulphonamides in patients with glucose-6-phosphate dehydrogenase deficiency. Antibiotics should as far as possible be avoided in pregnancy and when it is necessary to use an antibiotic, betalactam antibiotics and erythromycin are probably the safest. A history of allergy to antibiotics should always be sought before administration.

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Routine intradermal test doses for penicillin allergy is of little value and may even be dangerous. If in doubt avoid betalactams and use a macrolide or tetracycline (in adults) instead. In serious infections like meningitis and bacteraemic shock the immediate institution of the best available antibiotic for the suspected pathogen(s) is imperative as delay in treatment will increase both mortality and morbidity. In less serious situations such as otitis media where spontaneous recovery is common, an antibiotic that covers for the predominant organisms is adequate.

The antibiotic : 

The antibiotic The clinician should have adequate knowledge of the pharmacokinetic properties of the antibiotic he uses. Antibiotics vary in their ability to be absorbed orally or to cross the blood brain barrier and these factors will affect their routes of administration. The ability of the antibiotic to achieve therapeutic concentrations at the site of infection is another important consideration thus antibiotics used for treating urinary infections should ideally be concentrated in urine.

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Some antibiotics have very severe toxic effects and are best avoided in certain conditions. The doctor should also be aware of drug-drug interactions since many antibiotics can interact with other non-antibiotic drugs. Finally the cost of the antibiotic is also of major concern. In calculating costs it is perhaps more reasonable to take into account the total cost of treatment rather than just the actual cost of antibiotic per dose. The route of administration, the necessity for monitoring antibiotic levels and the patient's length of stay in hospital can affect the cost of treatment as well. The patient's compliance to medication is an important factor for consideration in the choice of antibiotics.

Choice of regimen Parenteral or oral : 

Choice of regimen Parenteral or oral Whether the route of administration should be oral or parenteral would depend on whether the patient is able to take oral treatment reliably. In cases of severe sepsis where rigors, hyperthermia/hypothermia, tachycardia and hypotension are present, intravenous therapy should be instituted. When in doubt it would be safer to commence intravenous treatment and review the treatment daily.

Duration of treatment : 

Duration of treatment Except for a few conditions, the optimum duration of antibiotic treatment is unknown. Many antibiotics are often presribed for a duration of 5-7 days. Nevertheless it is reasonable to discontinue therapy even after a shorter period if the patient's symptoms have resolved. There are however certain infections where prolonged treatment is necessary (Table I). In some conditions Eg : uncomplicated cystitis in women and gonococcal urethritis in males, single dose regimens have been shown to be effective.

Table I. Conditions where a minimum duration of treatment has been established. : 

Table I. Conditions where a minimum duration of treatment has been established.

Monitoring efficacy Early review of response : 

Monitoring efficacy Early review of response A routine early review ( 3 days after commencing treatment) of the patient's response is important in order to ensure that the patient is receiving appropriate treatment. After review the doctor will have to decide whether to: i) continue with the present regimen ii) increase the level of treatment by changing from oral to parenteral; increasing the dose or changing   to a broader spectrum antibiotic iii) decrease the level of treatment by changing from parenteral to oral, decreasing the dose or  changing to a more specific narrow spectrum antibiotic iv) stopping the antibiotic if the infection has resolved; the objective of treatment is achieved or   the diagnosis has been changed.

Inconsistent microbiology reports : 

Inconsistent microbiology reports If the patient is responding there is no necessity to change antibiotic even when the laboratory reports a resistant organism. The isolate in question could have been a coloniser or a contaminant. Infections may resolve spontaneously and the antibiotic could have affected the bacteria in a way that makes it more susceptible to the host's immune defenses. If the patient's condition fails to improve, a change in antibiotic may be necessary even when the laboratory reports a sensitive organism.

Causes of non-response to antibiotics : 

Causes of non-response to antibiotics A patient may fail to respond to an antibiotic for a number of reasons which include: i) the aetiological agent is resistant to the antibiotic ii) the diagnosis is incorrect iii) the choice of antibiotic is correct but the dose and/or route of administration is wrong iv) the antibiotic cannot reach the site of infection v) there is a colletion of pus that should be drained surgically or a foreign body/devitalised  tissue that should be removed vi) there is secondary infection vii) antibiotic fever viii) non-compliance of the host

Changing from intravenous to oral : 

Changing from intravenous to oral Wherever feasible intravenous therapy should be changed to oral therapy. The oral antibiotic (not necessarily the oral preparation of the intravenous antibiotic) should be selected based on clinical and laboratory findings. Similarly one should not hesitate to revert to intravenous therapy if the patient's condition warrants it.


GUIDELINES ON ANTIBIOTIC THERAPY The following guidelines are issued for the more common infections only. However even for common infections they may not apply to certain patients. When in doubt always seek a second opinion. The recommendations for first and second choice regimens are based on a global assessment of efficacy, adverse effects , prevailing sensitivity patterns and cost. It should also be noted that guidelines such as these have to be reviewed and updated from time to time.

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1. Erythromycin may be substituted for by a newer macrolide. 2. Gentamicin may be substituted for by another aminoglycoside depending on the local prevailing sensitivity pattern. 3. Where ampicillin is recommended amoxycillin may also be used.     Ampicillin/amoxycillin may be substituted for by a betalactam/betalactamase inhibitor combination depending on the local prevailing sensitivity pattern. 4. Cloxacillin is the drug of choice for severe methicillin-sensitive Staphylococcus  aureus. For oral therapy flucloxacillin is preferred to cloxacillin as the former is  more reliably absorbed and achieves higher tissue levels. In some children who  cannot tolerate cloxacillin a first or second generation cephalsoporin may be used. 5. Quinolones are not recommended in children.

Abbreviations: : 

Abbreviations: 1o : First generation 2o : Second generation 3o : Third generation







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WHO treatment revised and to be linked to  Model List of Essential Drugs : 

WHO treatment revised and to be linked to  Model List of Essential Drugs

References: : 

References: 1. Kass E H. Antimicrobial drug usage in general hospitals in Pennsylvania. Ann Int     Med 1976; 89 : 802 - 805. 2. Lim V K E, Cheong Y M and Suleiman A B. Pattern of antibiotic usage in hospitals     in Malaysia. Singapore Med J 1993; 34 : 525 - 528. 3. Ackerman V P, Pritchard R C, Groot Obink D J, Bradbury R and Lee A.     Consumer survey on microbiology reports. Lancet 1979; i : 199 - 203. 4. Cooke D, Salter A J and Phillips I. Antibiotic misuse, antibiotic policies and      information resources. J Antimicrob Chemother 1980; 6 : 435 - 443. 5. Obaseiki-Ebor E E, Akerele J O and Ebea P O. A survey of outpatient prescribing     and antibiotic self medication. J Antimicrob Chemother 1987; 20 : 759 -763. 6. Aswapokee N, Vithayapichet S and Heller R F. Pattern of antibiotic use in medical     wards of a University Hospital, Bangkok, Thailand. Rev Infect Dis 1990; 12 : 136 -     141. 7. Cheong YM, Lim VKE, Jegathesan M and Suleiman AB. Med J Malaysia 1994; 47     : 8. Kunin C M, Lipton H L, Tupasi T, Sacks T, Scheckler W E, Jivani A, Goic A,     Martin R  R, Guerrant R L and Thamlikitkul V. Social, behavioural and practical     factors affecting antibiotic use worldwide: Report of task force 4. Rev Infect Dis     1987; 9 (Suppl 1) : S270 - S285. 9. Fourth Western Pacific Congress on Chemotherapy and Infectious Diseases.     Consensus statement on policies and strategies for promoting appropriate antibiotic      use. Manila, 1994. 8. Williams J D. Antibiotic policy. Scan J Infect Dis 1986; Supplement 49 : 175 -181 9.Encyclopedia of clinical of pharmacy 857

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