Applied Pharmacy

Antimicrobial Stewardship

Empiric therapy is a bet placed before the data. Stewardship is settling the bet when the data arrive: narrow, switch to oral, set a stop date, or refuse to treat colonization at all. Susceptibility rows are S/I/R with the reasoning, never just letters.

The pneumonia that grew an answer

58-year-old admitted with community-acquired pneumonia; day 0 started on ceftriaxone + azithromycin empirically.

Improving: afebrile 24 h, eating, oxygen weaned.

The days unfold

Day 0
Blood + sputum cultures drawn; empiric ceftriaxone + azithromycin
Day 1
Sputum: gram-positive diplococci
Day 2
Culture: Streptococcus pneumoniae
Day 3
Susceptibilities below; patient ready for oral therapy

Portable chest radiograph in viral pneumonia with monitoring leads across the chest — Portable chest radiograph in pneumonia. The picture behind the stewardship case's culture.Hannover Medical School COVID-19 Image Repository (via the ieee8023 covid-chestxray-dataset) · CC BY 3.0

Sputum (good quality) + blood ×1 · Streptococcus pneumoniae

Agent	Result
Penicillin	S
Amoxicillin	S
Ceftriaxone	S
Azithromycin	RMacrolide resistance is common; this is why it was never a solo empiric plan
Levofloxacin	S

Day 3, ready for oral therapy. What does stewardship look like?

Empiric therapy is a bet placed before the data; stewardship is settling the bet when the data arrive. Narrow, switch to oral, name the stop date.

The line that grew MRSA

64-year-old dialysis patient, fever and rigors; blood cultures from line and periphery both flag gram-positive cocci in clusters.

Started empirically on vancomycin (level-guided) + piperacillin-tazobactam.

The days unfold

Day 0
Cultures; empiric vancomycin + piperacillin-tazobactam
Day 1
Clusters confirmed; awaiting identification
Day 2
MRSA confirmed in all bottles; susceptibilities below

Blood ×2 (line + peripheral) · Staphylococcus aureus (methicillin-resistant)

Agent	Result
Cloxacillin	RmecA: the definition of MRSA
Vancomycin	S
Daptomycin	S
TMP-SMX	S
Clindamycin	I

Day 2 decision set?

For S. aureus in blood, the antibiotic is half the treatment: source control, documented clearance, and a duration counted from negative cultures are the other half.

The urine that should not have been sent

82-year-old in long-term care; routine urine dip 'positive', culture grew E. coli.

No fever, no dysuria, no frequency, no new confusion. Baseline cognition, feels well.

The days unfold

Day 0
Screening dip sent 'because the urine smelled'
Day 2
Culture: E. coli >10⁸ CFU/L, susceptible to everything

Urine (no symptoms) · Escherichia coli

Agent	Result
Nitrofurantoin	S
TMP-SMX	S
Ciprofloxacin	S
Amoxicillin	S

What does the susceptibility panel change?

The strongest stewardship acts are refusals: no symptoms → no culture → no antibiotic. Smelly urine is hydration advice, not an indication.