Transcript Antibiotics
Internal Medicine Mini-Lecture
Learning Points
Basics
Choosing antibiotics
Overview
Basics
Make sure you try to collect cultures before
starting antibiotics
Many antibiotics require renal dosing, such as
vancomycin. If you’re unsure the dose call the
pharmacist.
ID approval is required for many antibiotics
such as vancomycin, levofloxacin,
ciprofloxacin. Call the ID fellow for approval
when required.
Use your Sanford Guide and hospital
antibiograms to help guide you
Sanford Guide now has an app for iphones –
very useful on the wards!
Epocrates app also has useful guides
Case
A 62-year-old man with history of poorly
controlled Diabetes, HTN, and
Hyperlipidemia presents with worsening
left lower extremity pain. Physical exam
reveals cellulitis and possible wound
infection, with concern for osteomyelitis.
Factors to consider when choosing
antibiotics
patient's recent antibiotic therapy
Hospital flora
presence of underlying diseases
available culture data – current AND past
risk for drug resistant pathogens:
receipt of antibiotics within the preceding 90
days
current hospitalization of ≥5 days
antibiotic resistance in the community
immunosuppressive disease and/or therapy
presence of risk factors for resistance
Choosing an antibiotic:
Think about Location:
Where did the patient become ill? Travel?
Exposure?
Where did the infection anatomically originate?
Where in the body, has or will the infection
spread to?
Think about the bug you are treating:
Consider
your bugs!
What are
you treating
or covering
empirically?
Antibiotic classes
Beta-lactams*
Aminoglycosides
Quinolones*
Macrolides*
Lincosamides*
Metronidazole*
Glycopeptides
Oxazolidinones
Streptogramins
Lipopeptides
Tetracyclines
Chloramphenicol
Polymyxins
Sulfonamides
Trimethoprim
Rifamycins
Nitrofurantoin
* These groups will be reviewed
further
B-Lactams: Penicillins
Penicillin
Use: pneumococcus, strep, enterococcus, N. meningitidis, syphilis,
listeria, leptospirosis and oral anerobes: peptostreptococcus and
prevotella
Amoxicillin
Use: Covers same stuff as penicillin and expanded activity against
gram negatives ( E.coli, Proteus,H. influenza, H. pylori, N.
meningitidis, shigella, klebsiella); covers most spirochetes including
lyme disease. Clavulanate enhances the gram negative spectrum to
include additional anaerobes such as bacteroides.
Oxacillin/Nafcillin/Dicloxacillin
Use: Only good for staphylococcal spp (except MRSA),
pneumococcus and other streptococci
Piperacillin and Ticarcillin
Use: Piperacillin covers pneumococcus, streptococcal spp including
enterococcus, gram negative including pseudomonas.
Does not cover MRSA.
B-Lactams: Cephalosporins
1st generation
Cefazolin:
Use: staph, non-enterococal strep; prophylactic in clean
surgeries, cellultis, folliculitis
Limitations: respiratory tract infections, animal bites or surgeries
involving the colon
2nd Generation
Cefuroxime:
Use: respiratory infections--Strep pneumoniae, H.influenzae and
M.cattarhalis; , meningitis due to pneumococcus,H.flu and
N.meningitidis.
Limitations: enteric organisms/abdominal anaerobes
Cefoxitin/Cefotetan:
Use: intra-abdominal infections especially anerobes
Limitations: staph and other gram positives
B-Lactams: Cephalosporins
3rd Generation
Cefotaxime & Ceftriaxone:
Use: Good for staph and non-enterococcal strep; broad
coverage of gram negative and oral anaerobes, CNS,
pulmonary, endovascular, GI infections (excluding gut
anaerobes), sinusitis, otitis, head & neck.
Limitations: does NOT cover Pseudomonas; ceftriaxone can
cause biliary sludging and limits its utility in treating biliary tree
infections
Ceftazidime:
Use: Good gram negative coverage including Pseudomonas;
febrile neutropenia CNS infections- good for Pseudomonas
meningitis
Limitations: reduced activity against the gram positives and oral
anaerobes.
4th Generation
Cefepime & Cefpirome:
Use: Enterobacter, Citrobacter and Serratia;Pseudomonas; gram
positives; used in neutropenic fever and CNS infections.
Beta-Lactams: Carbapenems
Imepenem:
slightly more activity against gram positive
bacteria than meropenem or ertapenem
Ertapenem:
Good for aerobic gram negatives
poor coverage of pseudomonas ,E. faecalis,
nocardia
Meropenem:
Good for aerobic gram negatives
Doripenem:
Good for CNS coverage and pseudomonas
Beta-Lactams
Cautions:
Beta-lactam allergy can occur in up to 10%
5%-10% cross-sensitivity in penicillin,
cephalosporins, and carbapenems
Side effects:
diarrhea, nausea, rash
Quinolones:
Ciprofloxacin:
Use: Covers most aerobic gram negatives including
Pseudomonas.
penetrates CNS, prostate, lungs
Limited against staph
Non-ciprofloxacin quinolones: Ofloxacin, Levofloxacin,
Moxifloxacin: Gemifloxacin:
Use: Great for respiratory pathogens, most enteric gram
negatives
Only levofloxacin covers pseudomonas
Covers some atypicals: Mycoplasma, Chlamydia, Legionella
Cautions:
Can cause Qt prolongation, tendon rupture, CNS toxicity
Do not use in patients with epilepsy or existing CNS lesions or
inflammation
Side effects:
Commonly causes C diff
Macrolides:
Erythromycin, Clarithromycin, Azithromycin
Use:
○ Broad spectrum against gram positives including
strep, staph aureus (MSSA)
○ Good for atypical oganism such as Mycoplasma,
Chlamydia, Legionella
○ Covers N.gonorrhea, H flu, Legionella
Caution:
○ can interact with statin to cause myopathy
○ Can cause Qt prolongation
Side effects:
○ GI upset
Lincosamides: Clindamycin
Use:
Reasonable gram positive aerobic coverage
against strep and many staph including MRSA
Special role in treating strep in necrotizing
fascitits
Anaerobic coverage better then penicillin but not
as good as metronidazole
Caution:
can interact with neuromuscular blocking agents
and cyclosporine
Side effects:
Diarrhea, commonly causes C difficile—avoid
clindamycin if other good options exist.
Metronidazole
Use:
No aerobic activity
Does not stand alone for mixed infections
Good coverage of anaerobes
Can be used for C diff, parasites, bacterial
vaginosis
Caution:
May require reduced dose in liver disease
Can increase effect of warfarin
Side effects:
Nausea, GI toxicity, antabuse reaction with Etoh;
headache, seizure, peripheral neuropathy with
prolonged therapy.
Antibiotic Coverage Quick Guide
1. Pseudomonas:
Zosyn
Aminoglycosides
Cephalosporins: Ceftazidine,
Cefepime
Fluoroquinolones: Cipro, Levaquin
Carbipenems: Imipenem, Meropenem
Aztreonam
Colistin
3. MRSA:
Bactrim
Clindamycin
Doxycyclin
Vancomycin
Linezolid
Tigecycline
Daptomycin – cannot use in lungs!
2. Anaerobes:
Flagyl – PO
Clindamycin – PO
Zosyn – IV
Unasyn – IV
Augmentin – PO
Carbipenem
Moxifloxacin
Tigecycline
4. VRE:
Linezolid
Tigecycline
Daptomycin