February 7, 2015 [ ]

Antibiotics

1. Penicillin : Strept. Except viridans √√ MSSA(Methicillin-sensitive Staphylococcus aureus)√ Enterococcus √

2. Ampicillin and amoxicillin : MSSA √ but only with added clav. Acid/sulbactam Strept. Except viridans √ Enterococcus √√ Anaerobes √√ Gm –ve but only with clav. Acid /sulbactam

3. Anti-staph penicillin (naficillin/dicloxacillin) MSSA √√ Strept. Except viridans √

4. Anti-pseudomonas penicillin (pipracillin/tazobactam) MSSA √ Strept. Except viridans √ Enterococcus √ Gm –ve √√ Anaerobes √√ Pseudomonas √√

5. Cephalosporins 1st gen: Gm +ve √√ except enterococci Gm –ve √ Anaerobes ±

6. Cephalosporins 2nd gen: Gm +ve √√ except enterococci Gm –ve √√ Anaerobes √√

7. Cephalosporins 3rd gen : Gm +ve √√ except enterococcus

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Antibiotic spectrum according to class

February 7, 2015 [ ]

Gm –ve √√ Anaerobes √ Pseudomonas : only ceftazidime(fortum) √√

8. Cephalosporins 4th gen: Gm +ve √√ except enterococci Gm –ve √√ Anaerobes √ Pseudomonas √√

9. Cephalosporins 5th gen (Ceftaroline ) : Gm +ve √√ except enterococcus Gm –ve √√ MRSA √√

10. Carbapenems (imipenem /meropenem/ertapenem):They cover all organisms except

MRSA Vancomycin resistant enterococcus (VRE) Acinetobacter Atypicals Stenotrophomonas

11. Quinolones (ciprofloxacin) MSSA √√ Gm –ve √√ Pseudomonas √√ Atypicals √

12. Quinolones (levofloxacin) Gm +ve √√ Gm –ve √√ Atypicals √√ Anaerobes ±

13. Quinolones (moxifloxacin) Gm +ve √√ Gm –ve √√ Atypicals √√ Anaerobes √ MRSA ±

14. Aminoglycosides

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February 7, 2015 [ ]

Used for serious aerobic gm –ve infections including pseudomonas , used with vancomycin/β lactams in cases of endocarditis

Contraindicated in renal failure and myasthenia gravis Ototoxic-nephrotoxic : tobramycin is the safest

- Main use for cephalosporins in summary1. 1st gen : gm +ve except MRSA2. 2nd gen : anaerobes3. 3rd gen : gm –ve + pseudomonas (fortum only)4. 4th gen : pseudomonas5. 5th gen : MRSA

- Cephalosporins do not cover enterococci- Fortum is the only 3rd gen against pseudomonas

- Imipenem and meropenem active against pseudomonas- Imipenem doesn’t cross BBB- Imipenem is always combined with cilstatin that inhibit human

dehydropeptidas enzyme- Carbapenems only IV route- Ertapenem is not active against enterococcus fecalis

- Penicillin G : strept A/B, strept pneumonia- Ampicillin/amoxicillin : strept A/B , strept pneumonia , enterococcus fecalis,

listeria- Ampicillin/amoxicillin + clav. Acid/sulbactam: MSSA, strept A/B, strept

pneumonia , enterococcus fecalis, listeria- Anti-staph penicillins : MSSA mostly- Anti-pseudomonal penicillins : MSSA, strept A/B, strept pneumonia,

enterococcus fecalis- Quinolones : strept A/B, strept pneumonia , enterococcus fecalis- Quinolones are bactericidal antibiotics mostly and don’t cross BBB

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Summary and notes

February 7, 2015 [ ]

- Macrolides : weak cover for strept A/B , pneumonia , listeria- Tetracyclines : strept pneumonia- Sulpha : MSSA, strept A/B, strept pneumonia , strept viridans , listeria- Clindamycin : strept A/B, strept pneumonia , anaerobes

MSSA - Naficillin √√- Cefazolin √- Vanco √

Coagulase-ve staph - Naficilli √√- Vanco √√- Carbapenems √

Strept A/B - Penicillin + clindamycin for A √√- Any β lactams √- Vanco √

Strept pneumonia - Penicillin G √√- Any β lactams √- Vanco √

Strept viridans - Penicillin G √√- Ceftriaxone √- Vanco √

Enterococcus fecalis - Ampicillin √√- Penicillin G √- Vanco √

Enterococcus facium - Ampicillin √√- Penicillin G √- Vanco √

listeria - Ampicillin ±gentamicin √√- Sulpha √- Carbapenems √

NB:

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Generally preferred drugs for gm +ve organisms

February 7, 2015 [ ]

- Staph = naficillin (except MRSA)- Strept = penicillin G / ceftriaxone- Enterococcus/listeria = ampicillin- For cases of severe allergy against ampicillin , vanco is a good choice

Risk factors:

- Recent excess use of cephalosporins/quinolones for MRSA or vanco for VRE- Longterm hospitalization- Hemodialysis

Drug of choice:

- Vancomycin : MRSA√√ Side effects: red man syndrome , nephrotoxic , ototoxic ,neutropenia Poor BBB crossing

- Daptomycin: MRSA √√ VRE √√ Side effects : myopathy , neuropathy , esinophilia

- Linezolid: MRSA √√ VRE √ Side effects : lactic acidosis , serotonin syndrome ,neuropathy, optic

neuritis- Ceftaroline

2nd gen cephalosporins - E-coli- H.influenza

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Resistant bacteria

Generally preferred drugs for gm –ve organisms

February 7, 2015 [ ]

- Klebsiella- Proteus

3rd gen cephalosporins - The same+ Neisseria4th gen cephalosporins - The same +citrobacteria

and neisseriaAmoxicillin/ampicillin+ clav. Acid/sulbactam

- As 3rd gen

Anti-spseudomonal penicillins - As 4th genCarbapenems - As 4th genAztreonam - As 2nd genQuinolones - All except NeisseriaAminoglycosides - All except neisseria

Pseudomonas mainly

Others: stenotrophomonas ,ESBL

Drug of choice:

- Ceftazidime : √√pseudomonas , only one in 3rd gen- Cefipime: pseudomonas √√ , false +ve coombs test- Pipracillin/tazobactam: pseudomonas √√ , ↓ PLT- Carbapenems except ertapenem : pseudomonas and ESBL √√- Aztreonam : weak anti-pseudomonal- Aminoglycosides : pseudomonas √√ , poor lung penetration , ototoxic ,

nephrotoxic

NB:

1. Ciprofloxacin & levofloxacin have good anti-pseudomonal activity2. Ampicillin sulbactam has good cover for acinetobacter

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Resistant negative strains

February 7, 2015 [ ]

3. Sulpha is good for stenotrophomonas and can be used if no contraindications

When should we cover anaerobes even if there’s no growth?

- periodontal infections - Infections of deep spaces of neck- Aspiration pneumonia- Lung abscess- Empyema- Intra-abdominal abscess- Secondary peritonitis

metronidazole - Bacteroids √√- Clostridia √√- Metallic taste

carbapenems - Fair for all organisms but ertapenem is not preferred

Β lactams + clav. Acid/sulbactam - Fair against all organisms- ↓PLT

clindamycin - Fair for all organisms- Q 6hrs ↓compliance

2nd gen cephalosporins - Fair against allmoxifloxacin - Fair against actinomyces

- QT prolongation- Not recommended for pediatrics

chloramphenicol - Excellent against all except c. difficile

NB:

- If infection above diaphragm use clindamycin

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Generally preferred drugs for anaerobic infections

February 7, 2015 [ ]

- If infection below diaphragm use metronidazole- If generalized use β lactams + clav. Acid/sulbactams &moxifloxacin- Metronidazole should never be used as monotherapy except for c. difficile

that is the most common cause for infection colitis due to antibiotic use- Most gut flora is gm –ve- Vanco can be used for TTT of c. difficile but only oral because IV route is

poorly absorbed in GIT

Mycoplasma pneumonia - Atypical pneumoniaChlamydia trachomatis - PID

- Urethritis- Prostatitis- Pneumonia in neonates

Chlamydophila pneumonia - Atypical pneumoniaChlamydophila pisittaci - Bird transmissionrickettsia - Typhuslegionella - Atypical pnemonia

Drug of choice:

1. Macrolides : √√ all except rickettsia Side effects : QT prolongation , hepatic injury , exacerbate

myasthenia gravis2. Tetracycline :

√√ all except legionella Side effects: esophagitis , hyperpigmentation Should be taken with plenty of fluids

3. Quinolones:

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Generally preferred drugs for atypical organisms

February 7, 2015 [ ]

√√ for all except rickettsia Side effects : QT prolongations , exacerbate myasthenia gravis

4. Chloramphenicol: √√ for all except legionella Side effects : aplastic anemia

mycoplasma Doxycycline √√ Azithromycin √ Quinolones √

chlamydia Doxycycline √√ Azithromycin √√ Levofloxacin √

rickettsia Doxycycline √√ Azithromycin √ Quinolones √

legionella Levofloxacin √√ Moxifloxacin √√ Azithromycin √

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Key√√ means excellent activity

√ means good

activity± means

not always active