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MODULE 42: MASTERING CLINICAL SURVEILLANCE
Lesson 3: Anti-infective Stewardship
Leveraging surveillance to champion the core principles of stewardship: the right drug, for the right bug, at the right dose, for the right duration.
LESSON 3
Anti-infective Stewardship
Using real-time data to become a high-impact stewardship champion.
31.3.1 The Surveillance Pharmacist as Stewardship Champion
Antimicrobial Stewardship is one of the most critical functions of any hospital pharmacy department. It is our collective professional responsibility to ensure these life-saving drugs are used wisely to optimize patient outcomes while minimizing the development of resistance. Traditionally, much of this work has been done through manual chart reviews, retrospective data analysis, and prospective audits—all labor-intensive processes. Clinical surveillance technology fundamentally revolutionizes this practice. It transforms antimicrobial stewardship from a series of manual tasks into a dynamic, real-time, data-driven discipline.
As a surveillance pharmacist, you are on the front lines of modern stewardship. You are the first to know when a critical culture result posts, the first to detect a potential bug-drug mismatch, and the first to identify an opportunity for de-escalation. Your surveillance inbox becomes the central nervous system of the stewardship program, feeding you a prioritized list of patients who require your expert intervention. This lesson will provide a deep dive into the most common and highest-impact stewardship scenarios you will manage, giving you the clinical framework and practical tools to translate these data signals into decisive, patient-centered action.
31.3.2 The “Positive Blood Culture” Alert: From Signal to Action
Few alerts carry more weight or urgency than one for a newly positive blood culture. This is a critical, Tier 1 alert signaling bacteremia or fungemia, a potentially life-threatening condition. Your ability to rapidly assess the situation and provide expert guidance on empiric therapy can directly impact patient survival. The initial alert is often based on the first signal from the lab: the Gram stain result. This is your first clue in the mystery, and you must become an expert interpreter.
Masterclass Table: Interpreting the Initial Gram Stain
| Gram Stain Result | Commonly Implied Pathogens | Typical Sources & Clinical Implications | Immediate Empiric Therapy Considerations |
|---|---|---|---|
| Gram-Positive Cocci in Clusters (GPCc) | Most likely Staphylococcus species (e.g., S. aureus, Coagulase-Negative Staph). | Source: Often skin flora. Think line infections (central or peripheral), skin/soft tissue infections, endocarditis.
Implication: High likelihood of Methicillin-Resistant S. aureus (MRSA). Empiric coverage for MRSA is almost always required. |
Your first question: Is the patient already on Vancomycin or another MRSA-active agent? If not, this is a Tier 1 emergency. An immediate recommendation to start Vancomycin is warranted. |
| Gram-Positive Cocci in Chains/Pairs (GPCch) | Most likely Streptococcus or Enterococcus species. | Source: Varies. Strep pneumo (respiratory), Viridans Strep (endocarditis), Enterococcus (urinary, intra-abdominal).
Implication: For Enterococcus, need to consider Vancomycin-Resistant Enterococcus (VRE) risk. |
If the patient is critically ill (septic shock), broad coverage (e.g., Vancomycin) is often started. If stable, you might await further identification, but if enterococcus is suspected, VRE coverage (Linezolid, Daptomycin) may be needed based on patient risk factors. |
| Gram-Negative Rods (GNR) | Large, diverse group including E. coli, Klebsiella, Proteus (common) and Pseudomonas aeruginosa (high-risk). | Source: Most commonly urinary tract or intra-abdominal. Can also be from pneumonia (especially hospital-acquired).
Implication: This is a sepsis red flag. The main question is the risk for multi-drug resistant (MDR) organisms, especially Pseudomonas. |
Assess the patient’s risk factors for Pseudomonas (recent hospitalization, prior MDR infections, immunosuppression). If low-risk, Ceftriaxone may be sufficient. If high-risk, broad-spectrum anti-pseudomonal coverage (e.g., Piperacillin-Tazobactam, Cefepime, Meropenem) is urgently needed. |
| Yeast / Fungal Elements | Almost always Candida species. | Source: Almost always a central line, TPN, or severe immunosuppression.
Implication: Candidemia. This is a life-threatening infection with high mortality. Immediate antifungal therapy and source control are required. |
This is a Tier 1 emergency. An immediate recommendation to start an echinocandin (e.g., Micafungin, Caspofungin) is the standard of care. You must also strongly recommend evaluation of all central lines for removal (“source control”). |
Case Study A: The Gram-Negative Rod Alert
The Alert: At 2:00 AM, a Tier 1 alert fires: “New Positive Blood Culture: Gram-Negative Rods” for a 78-year-old male in the ICU.
Pharmacist’s AIPLOL Review (90 seconds):
- A (Allergies): None listed.
- I (Indication): Admitted for urosepsis, now in septic shock.
- P (PK/PD): Currently on Ceftriaxone 1g IV daily (started in ED).
- O (Organs): New AKI with SCr 2.5 (baseline 1.2).
- L (Lines): Central line present.
- L (Labs/Logs): Vitals show persistent hypotension (SBP 85) despite fluids, requiring vasopressors. Lactate is elevated at 4.2.
Pharmacist’s Assessment & Action: “This patient is in septic shock with GNR bacteremia and is not improving on ceftriaxone. Given his severity of illness and hospital setting, his empiric coverage is too narrow and does not cover for Pseudomonas. This requires immediate escalation.”
The Intervention (Direct Phone Call to ICU Physician): “Hi Dr. Smith, this is the surveillance pharmacist. I’m calling about your patient in ICU Bed 5. His blood culture just came back positive for gram-negative rods. Given that he is in septic shock and not responding to ceftriaxone, I strongly recommend we broaden his coverage for resistant organisms. Per our stewardship protocol, Piperacillin-Tazobactam (Zosyn) would be the appropriate next step. I can enter a verbal order for a renally adjusted dose if you agree.”
31.3.3 PK/PD Surveillance: Vancomycin and Aminoglycosides
Beyond identifying the right bug and right drug, stewardship is about ensuring the right dose. For drugs with narrow therapeutic indices like vancomycin and aminoglycosides, therapeutic drug monitoring (TDM) is essential. Surveillance systems are powerful tools for optimizing TDM by alerting you to out-of-range levels and flagging patients at risk for toxicity.
The Paradigm Shift: Vancomycin AUC/MIC Monitoring
For decades, vancomycin was dosed to target a simple trough level, typically 15-20 mcg/mL for severe infections. However, modern evidence has shown that the trough is a poor surrogate for efficacy and is a primary driver of nephrotoxicity. The 2020 IDSA/ASHP/SIDP guidelines now recommend targeting an Area Under the Curve to Minimum Inhibitory Concentration ratio (AUC/MIC) of 400-600 mg*h/L to optimize efficacy while minimizing the risk of AKI.
Your surveillance system is key to implementing this. It can automatically calculate the AUC from timed levels or flag patients whose troughs suggest they are far outside the AUC target. Your role is to use this data to move your institution away from trough-based dosing and toward safer, more effective AUC-based regimens.
The Pitfall of the “Trough-in-Range” Complacency
A trough of 18 mcg/mL might seem perfect under the old guidelines, but for a patient receiving a high dose (e.g., 1.5g q8h), this could correspond to a dangerously high AUC of >700, significantly increasing their AKI risk. Conversely, a “low” trough of 12 mcg/mL might actually correspond to a perfectly therapeutic AUC of 450 in a patient with poor renal function. Do not trust the trough alone. Your surveillance alerts should be built to drive you toward an AUC-based assessment.
Case Study B: The “High Trough” Vancomycin Alert
The Alert: A Tier 1 alert fires: “Supratherapeutic Vancomycin Trough” for a 62-year-old male. The trough level is 28 mcg/mL.
Pharmacist’s AIPLOL Review (90 seconds):
- A (Allergies): Sulfa (rash).
- I (Indication): MRSA bacteremia from an infected decubitus ulcer.
- P (PK/PD): Patient has been receiving Vancomycin 1250mg IV q12h for 4 days. The trough was drawn appropriately before the 5th dose.
- O (Organs): Renal function has been declining. SCr was 1.4 on admission and is now 2.1 today. Calculated CrCl has dropped from 60 to 40 mL/min.
- L (Lines): Central line present.
- L (Labs/Logs): All prior troughs were in range (15-18). This is an acute change coinciding with the decline in renal function.
Pharmacist’s Assessment & Action: “The high trough is a direct result of the patient’s developing AKI. He is not clearing the drug as expected. The immediate priority is to hold the next dose to prevent further accumulation and toxicity. The second priority is to re-calculate a new, safer regimen based on his current, lower renal function and a target AUC.”
The Intervention (Two-Sentence Note via Secure Chat, followed by a call if no response in 15 min): “To prevent worsening nephrotoxicity, recommend holding the next dose of vancomycin based on a critical trough of 28 mcg/mL in the setting of acute kidney injury. Suggest rechecking a level in 24 hours and I will provide a new AUC-based dosing recommendation at that time.”
31.3.4 The Stewardship “Endgame”: IV-to-PO, Duration, & C. diff Prevention
Effective stewardship isn’t just about starting the right drug; it’s about knowing how and when to stop. The “endgame” of antibiotic therapy is just as important as the opening move. Surveillance systems are perfectly suited to identify these opportunities to transition therapy, shorten durations, and reduce the collateral damage of antibiotic use, such as Clostridioides difficile infection.
Masterclass Table: High-Bioavailability Antibiotics for IV-to-PO Conversion
| Antibiotic Class | Agent(s) | Oral Bioavailability | Common IV-to-PO Dosing Conversion |
|---|---|---|---|
| Fluoroquinolones | Levofloxacin, Moxifloxacin, Ciprofloxacin | Excellent (>90%) | Generally 1:1 conversion (e.g., Levofloxacin 750mg IV daily → 750mg PO daily). |
| Oxazolidinones | Linezolid, Tedizolid | Complete (100%) | 1:1 conversion (e.g., Linezolid 600mg IV q12h → 600mg PO q12h). |
| Azole Antifungals | Fluconazole, Voriconazole | Excellent (>90%) | 1:1 conversion (e.g., Fluconazole 400mg IV daily → 400mg PO daily). |
| Miscellaneous | Metronidazole, Doxycycline, Clindamycin, Bactrim | Very Good (>80-90%) | All are typically 1:1 conversions based on their respective dosing regimens. |
| Beta-Lactams | Amoxicillin, Amoxicillin/Clavulanate, Cephalexin | Variable (Good, but not 1:1) | This is not a direct 1:1 switch. This is a “step-down” from a broader IV beta-lactam (e.g., Ceftriaxone) to a suitable oral beta-lactam based on culture sensitivities for less severe infections (e.g., step-down to PO Augmentin for a UTI). |
The IV-to-PO Surveillance Rule: A typical rule will fire an alert when `(Patient is on a target IV antibiotic for >48 hours) AND (Patient is afebrile for 24 hours) AND (WBC is trending down) AND (Patient is on a PO diet)`. When you receive this alert, it is a Q3 “Quick Win” opportunity.
Duration Control & C. diff Prevention
One of the most significant drivers of antibiotic resistance and C. diff infection is excessively long courses of therapy. Surveillance rules can be built to fire simple reminders based on diagnosis and days of therapy.
The Duration Reminder Alert: `Patient admitted with Community-Acquired Pneumonia (CAP) AND has been on antibiotic therapy for 5 days AND is clinically stable.`
Your Intervention: This is an opportunity for a non-urgent secure message. “Per IDSA guidelines for CAP, 5 days of therapy is often sufficient for a patient who is clinically stable. Patient has been afebrile for 48 hours. Please consider discontinuing azithromycin at this time to complete the course of therapy.”
31.3.5 Retail Pharmacist Analogy: From Dispenser to Disease State Manager
A Deep Dive into the Analogy
The transition from traditional verification to stewardship-focused surveillance is the same as the transition many retail pharmacists make from simply dispensing medications to running a high-touch clinical service or disease state management program.
1. The Positive Blood Culture Alert is the “Emergency” MTM Case.
Imagine you’re running your MTM platform and you get a notification that one of your enrolled patients, Mr. Smith, just had a prescription filled from the Emergency Department for both an ACE inhibitor and an ARB—a major therapeutic duplication. You don’t just file this information away. This is a critical, unscheduled intervention. You immediately stop what you’re doing, pull up Mr. Smith’s full profile, and call him or the ER to resolve the duplication and prevent potential harm. This is the exact same priority and workflow as a STAT positive blood culture alert.
2. PK/PD Monitoring is Your In-House Anticoagulation Clinic.
If you’ve ever worked in a pharmacy with a pharmacist-run anticoagulation or diabetes clinic, you are already a surveillance expert. You’re not just dispensing warfarin. You are proactively managing a population of patients. You have a list of everyone on warfarin, you systematically track their INR results, you use a nomogram or protocol to make dose adjustments, and you document your interventions. This is a perfect real-world analog to monitoring vancomycin AUCs or aminoglycoside levels. The technology is different, but the clinical mindset of proactive population management is identical.
3. IV-to-PO, Duration, and De-escalation is Proactive “Deprescribing.”
One of the most valuable services in community MTM is deprescribing—identifying medications that are no longer needed. When you perform a comprehensive medication review, you might notice a patient has been on a PPI for years without a clear indication, or is still using an antibiotic for a UTI that should have been finished a week ago. Your recommendations to stop these medications to reduce cost, pill burden, and long-term risks (like C. diff from the antibiotic or bone fractures from the PPI) is the exact same clinical logic as recommending an IV-to-PO switch or a shorter duration of therapy in the hospital. You are optimizing the “endgame” of therapy to provide safer, more efficient care.
