Rational use of Antibiotics

Dr Malika KarunaratneConsultant Microbiologist

NIHSKalutara

Introduction

• Different from other drugs- misuse can affect the response of future

patients. Irrational use – major problem-development

of resistance

• Few groups of antibiotics to attack large number of bacterial spp

Cost of antibiotics

Not just the unit cost of the antibiotic

Materials for administration of drug

Labour costs

Cost of monitoring levels

What is Rational Use?

• Is an antibiotic necessary?

All fevers are not due to infections All infections are not due to bacteria All bacterial infections does not need antibiotics- consider other options: surgery , antiseptics, self

limiting There is no evidence that antibiotics will prevent

secondary bacterial infection in patients with viral infection

What is Rational Use?

• Correct antibiotic / choice of antibiotic

• Start at the correct time

• Correct dosage and correct route

• Correct duration

Correct antibioticfor empiric therapy

Community acquried infection- • Eg-pneumonia. UTI, skin infections• usually from pathogens sensitive even to

narrow spectrum antibiotics Hospital acquired infections –• Eg- SSI, VAP, HCA UTI , etc• pathogens are multi drug resistant- broad

spectrum antibiotic as the first line therapy

Correct antibiotic? For empiric therapy

causative agents /most likely pathogen depends on the site of infection

– Skin infections –Staph,Strep, rarely Coliforms/Pseudo

- Surgical prophylaxis – Mainly to cover skin carriers

– known colonizer (MRSA/ESBL?)

• No anarobic activity – aminoglycoside/quinalones/cephalosporins

• No Gram negative cover – clox/glycopeptides/clindamycin

• No gram positive cover – aztreonam /ceftazidime

• Less anti staph cover - CTX/CRO• Ciprofloxacin-no Pneumococcal cover• Nalidixic acid- no Staphylococcaal cover

Correct antibiotic? cont

Adequet concentration at the site

• concentrated well in bones-ciprofloxacin/fusidic acid

• Prostate – quinalones• Penetrate into deep abscesses clindamycin• 1st and 2nd gen cephalosporins,

aminoglycosides- no CSF penetration

Correct antibiotic

• Severity of the infection

• Host factors and side effects– age, renal and hepatic involvt, pregnancy allergies ect

• Antibiotic sensitivity patter of the likely pathogen - before ABST results

local sensitivity data vary from country to country ,hospital to hospital and from unit to unit

Best guess principle for correct antibiotic

• Predicting the most likely pathogen• Most likely site• The antibiotic sensitivity pattern CA/HA• local susceptibility patterns of micro organisms- • Severity of the patients illness• patient factors• Current national and local guidelines – BNF recommendations local guidelines

Correct antibiotic? Specific therapy

• Interpretation of the ABST report- what is isolated is not necessarily the pathogen. It could be a contaminent or colonizer

Was the specimen properly collected? / proper container?

sensitivity reports are at best a guide

Correct time

• As soon as diagnosis of infection made and (appropriate sp have been collected)

• Surgical prophylaxis – One hour prior to skin incision do you continue this until drain tubes are

removed?

Correct dosage

• BW

• Ability of the drug to penetrate into site of infectionHigher doses/prolonged therapy poor drug penetration to the site, difficult to eradicate

infections eg- Endocarditis septicaemia, meningitis , brain

abscess

• Impairment of excretion – dose adjustments

Correct route

• Severe infections – IV therapy

• Endocarditis septicaemia, meningitis – always parenteral

• Topical antibiotics- use only in clearly defined clinical situations -

Eg- ENT and opthalmic infectionsabsorb in sub theraputic dosages- promote resistance

development

Correct duration

• Duration varies.

• usually 7 to 10 to 14 days (Severity of the infection , Clinical and Biochemical

response)

• deep seated, difficult to eradicate from the site longer duration- 4-6 weeks

• Removal of pus – shorter duration

Correct durationDuration varies.

– All prescriptions must be reviewed after 5 days of rx.

– In severe infections prescriptions MUST BE REVIEWED in 24- 48 H to assess the clinical response

• All IV prescriptions MUST BE REVIEWED after THREE DAYS

• IV antibiotics can be switched to oral equivalents after 48 - 72 hrs if,

• temp <38 at least for 24 hrs• clinical improvement observed• WBC and CRP improving• haemodynamically stable• oral route viable

• UNLESS AN EXTENDED IV DURATION IS SPECIFICALLY STATED. ( Meningitis, Endocarditis, Osteomyelitis, Septic arthritis, Discitis, Bacteraemia (positive BC), Necrotizing fasciitis)

Combination therapy increase the spectrum of antibacterial activity -• Empirical therapy – causative organism is not known• Prevention of drug resistance eg – anti TB therapy fusidic acid alone

• Polymicrobial infections intra abdominal and pelvic infections,braain abscess

• immunocompromised pt• Synergistic effect – endocarditis• To allow dose of a toxic agent to be reduced

• Not properly combined- antagonism

Clinical problems

• 5 year old boy • Came to OPD with his mother• Fever, running nose, cough for 2 days

• O/E• Fever 101 F• Lungs – clear

Probable diagnosis?

What is your management?

• Probable diagnosis –Acute bronchitis/ commonly Viral in origin

• What is your management?• Symptomatic treatment• No antibiotics

All infections are not due to bacteria

Do you give antibiotics to prevent secondary bacterial infections?There is no evidence that antibiotics will prevent secondary bacterial

infection in patients with viral infection

Meta-analysis of 9 randomised placebo controlled trials involving 2249 patients

Conclusions: There is not enough evidence of important benefits from the treatment of upper respiratory tract infections with antibiotics and there is a significant increase in adverse effects associated with antibiotic use.

Arroll and Kenealy, Antibiotics for the common cold. Cochrane Database of Systematic Reviews. Issue 4, 2003

• 69 year old female• Presented to OPD• Fever 5 days• Cough with yellow sputum• crepitations++• No recent exposure to antibiotics/no co morbidities

• What is your management

• CXR--- no consolidation• (WBC/DC – 15,000 mg/dl , neutrophil 80%)

• Amoxycillin 500mg 8hrly / • Cefuroxime 500mg 12hrly oral 5-7 days/• R/V in3days or before

• If above patient is presented with dyspnoea • CXR – Shadow at the R lung base• CURB 65 is 2 – moderate CAP

• What will you do?• admit- IV therapy is indicated.• Ix- blood culture/sputum culture/CRP

• If CURB 65 is 3 – severe CAP- patient needs urgent admission and IV antibiotics

• Common organisms for CA P• Strep.pneumoniae• Heamophilus influenzae• Mycoplasma pneumoniae

• Cefotaxime 1g 8hrly/ Ceftrioxone 1g daily/ Co-amoxyclav 1.2g 8 hrly

• + Clarythromycin 500mg 12 hrly• Consider PO step down after 48 hours if patient ‐

improving

• If CURB 65 is 4 or more –ICU

• Severe CAP in ICU- inaddition, consider antipseudomonal cover

• Levofloxacin is an option for high severity pneumonia not responding to Co-amoxiclav/clarythro combination

• ACUTE EXACERBATION OF COPD (No consolidation on Chest X ray ,no history of antibiotic exposure ‐with in last 3 months)

Only give antibiotics if 2 or more of the following are present

• • ↑ breathlessness •↑ sputum volume •↑ purulent sputum

• Amoxicillin 500mg TDS PO for 7 days OR Co-amoxiclav 625mg tds or Clarithromycin 500mg BD PO for 7 days

• SINUSITIS• Acute – most cases are viral, treat with

analgesics/anti inflammatories /steam for 3 ‐days

• Thereafter treat as chronic• Chronic 1st line: Co amoxiclav 625mg TDS PO ‐

for 5 days

BACTERIAL TONSILLITIS

Do you treat?Do you use co-amoxiclav?• 1st line: Penicillin V 500mg QDS PO for 10 days

• 2nd line (Penicillin allergy): Clarithromycin

500mg BD PO for 10 days

• BONE AND JOINT INFECTIONS

Unless the patient has clinical features suggesting ‘sepsis’ relating to their bone or joint infection it is better to delay antibiotic therapy until appropriate sampling has been undertaken

• 70 years old patient with chronic wound• no fever• no redness/unusual swelling/surrounding cellulitis• DIAGNOSIS- DIABETIC FOOT ULCER

Do you treat him with antibiotics?• Do not treat with antibiotics unless evidence of

infection• Always seek specialist advice

• BITES• Is an antibiotic necessary?

• YES

• Prophylactic co amoxiclav

• 30 year old woman• 2 days dysuria, increased frequency• No fever• No recent history of UTI

• Uncomplicated UTI(non pregnant female with no anatomical or functional defect)

• Organisms E.Coli Staph. Saphrophyticus

• Urine culture – not essential, if facilities are there test can be performed

Nitrofurantion Nalidixic acid-? Coamoxyclav Cephalexin/ cefuroxime

• 45years old patient came to OPD with watery stools 5-6 times /day for last 24 hours

• fever + , No blood in stools• no evidence of dehydration What is your management?

Salmonellosis- zoonotic, self limitingShigellosis- if severe infection, blood and mucus

• Antibiotics are indicated only for severe diarrheoa – watery stools more than 6 times per day, blood and mucus , extremes of age, immunocompromised

TAKE HOME MESSAGE

Antibiotic resistance is a major problem world-wide

Resistance is inevitable with use No new class of antibiotic introduced over

the last two decades Appropriate use is the only way of prolonging

the useful life of an antibiotic