1. Common ID Syndromes
March 2014

2. objectives Identifying the bug Choosing the antibiotics
Empiric coverage for common ID scenarios

3. Basics Try to collect cultures before starting antibiotics
Renally dose antibiotics (esp Vanco, levaquin)
Call the ID fellow for approval when required
Use Sanford Guide and hospital antibiograms
Sanford Guide now has a mobile app
Epocrates app also has useful guides

4. Consider your bugs!
What are you treating or covering empirically?

5. Common ID Syndromes (covered in this lecture)
Bacterial Meningitis
Infective Endocarditis
Clostridium Difficile
Urinary Tract Infections
Cellulitis
CAP & HCAP (covered elsewhere)

6. Bacterial Meningitis Common causes of meningitis: Diagnosis: LP
S. pneumoniae (30-50%)
Neisseria meningitidis (10-35%)
Listeria (2-11%)
Other less common include:
Gram-negative; Streptococci; Staphylococci; H. influenzae
Diagnosis: LP
Gram stain, C&S, cell count w/ diff, protein, and glucose
Empiric treatment for Suspected Bacterial Meningitis
3rd gen cephalosporin (ceftriaxone or cefotaxime), PLUS
Vancomycin, +/-
Ampicillin (if at risk for Listeria: age >60 or neonate)

7. Infective Endocarditis
Obtain 3 sets of blood cultures
Diagnosis: Modified Duke Criteria
Definite endocarditis:
Pathologic evidence of disease OR
2 Major clinical criteria OR
1 Major + 3 minor OR
5 minor
Possible endocarditis
1 Major + 1 minor OR
3 minor
Pathologic evidence of disease (on Echo with vegetation or valve lesion or +culture from same tissue)

8. IE Major and minor criteria
Major Criteria
1) Positive blood cultures (specific criteria)
“Typical” organisms: S. aureas, viridans strep, S. Bovis, enterococci, and HACEK
2) Abnormal echocardiogram
Minor Criteria
1) Predisposing condition (valve disease or IVDA)
2) Fever
3) Vascular phenomena
4) Immunologic phenomena
5) Positive blood culture that does not meet a major criterion
Major criterion:
organisms should be “typical” (S. aureas, viridans strep, S. Bovis, enterococci, HACEK) from 2 separate cultures at least 12 hours apart
- If suspecting HACEK, call lab for slow-growing organisms
2. Any other organisms should be in at least 3 or a majority of 4 or more cultures
3. Any 1 blood culture that grow C. burnetti is significant

9. Treatment of IE Organisms Susceptibility Drug Regimen Duration
Viridans streptococci,
S. Bovis
PCN-sensitive
PCN G or CTX
4 weeks
Prosth >4 weeks
(PCN G or ctx) + gent
2 weeks
Vancomycin (alt)
PCN-resistant
Increased dose PCN G
S. Aureus or
Coagulase-neg
Methicillin-susc
Nafcillin
6 weeks
Prosthetic (add rifampin & gent)
Methicillin-resis
Vancomycin
Staph, uncomplicated right-sided
Nafcillin + gentamicin or daptomycin
Enterococci
PCN-sens
(PCN G or amp or vanc) + gent
4-6 weeks
Prosth = 6 weeks
Amp + PCN + Vanc-resis
Very specialized
HACEK
Ceftriaxone
Source MedStudy 15th edition
Enterococci resistant to amp, PCN G, vanc  utilize variations of linezolid and imipnem/cilastin with either amp or ceftriaxone

10. Diarrhea due to C. difficile
Common causes:
Clindamycin, cephalosporins, quinolones
Diagnosis:
Confirm with stool assay for cytotoxin
Recommendations:
Mild-to-moderate: Flagyl 500mg po tid x days
Severe disease: Vanco 125mg po qid x days
Severe with complications: P.O. Vanco +/- IV Flagyl
1st relapse: Repeat the first regimen
2nd relapse: Vanco 125mg po qid and taper

11. Urinary tract infection
Microbiology for uncomplicated UTI:
E. coli (most common 75-95%)
Other species of Enterobacteriaceae:
Proteus mirabilis (associated with stones, do add’l workup)
Klebsiella pneumoniae
Staphylococcus saprophyticus
Group B strep (in pregnant women, otherwise contaminant)
Likely contamination in healthy non-pregnant individuals:
(lactobacilli, enterococci, coag-neg staph)
Broader for complicated (pseudomonas, serratia, providencia species, enteroccci, stapylococci, fungi)

12. Urinary Tract Infection
Acute uncomplicated cystitis-urethritis
Bactrim 160/800 (1 DS tab) bid x 3 days OR
Macrobid 100mg bid x 5 days OR
Fosfomycine 3g po (single dose)
Uncomplicated pyelonephritis
Ciprofloxacin 500mg bid x7 days OR
Ceftriaxone or quinolone (if requiring IV)
Complicated pyelonephritis
Ceftriaxone, cefepime, aztreonam, or quinolone
Add expanded coverage if ICP or urinary obstruction
Asymptomatic bacteruira: treatment indicated only in pregnant women and men/women undergoing invasive urologic procedures
Acute complicated UTI is associated with an underlying condition that increases the risk of infection or of failing therapy (such as obstruction, anatomic abnormality, urologic dysfunction, or a multiply-resistant uropathogen; progression of upper UTI to emphysematous pyelonephritis, renal corticomedullary abscess, perinephric abscess, or papillary necrosis.

13. Cellulitis
Purulent (drainage or exudate w/o drainable abscess) – d/t community-acquired MRSA
Clindamycin mg po tid
Bactrim 1 DS tab bid
Doxycycline 100mg bid
Minocycline 200mg x1, then 100mg bid
Linezolid 600mg bid
Non-purulent – d/t beta-hemolytic strep and MSSA
Systemic toxicity requires parenteral antibiotics
Standard empiric treatment includes coverage for both MRSA and beta-hemolytic streptococci (options: Clindamycin; Amoxicillin + Bactrim or tetracyclin; Linezolid) PO IV
Dicloxacillin 500mg q6h
Cefazolin 1-2g q8h
Keflex 400mg q6h +/- Bactrim
Oxacillin 2g q4h
Clindamycin mg q6h
Nafcillin 2g q4h
Clindamycin mg q8h

14. 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!
4. VRE:
Linezolid
Tigecycline
Daptomycin
2. Anaerobes:
Flagyl
Clindamycin
Zosyn
Unasyn
Augmentin
Carbipenem
Moxifloxacin
Tigecycline

15. Take home points Deescalate antibiotics based on sensitivities
Antibiotics should be individualized based on patient circumstances (allergy, tolerability, compliance), local community resistance prevalence, availability, cost, and patient and provider threshold for failure