Clinical Decision Making Discussion

Sample Solution

H-M: How does the empiric pharmacological therapy differ in a patient with healthcare-associated meningitis (such as a neurosurgical patient with an external ventricular drain) as compared to a healthy adult with community-acquired bacterial meningitis? Explain your rationale.

The empiric pharmacological therapy for healthcare-associated meningitis (HAM) differs from community-acquired bacterial meningitis (CABM) in several ways.

Differences in the most common causative organisms:

• CABM is most commonly caused by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b.

Full Answer Section

• HAM is most commonly caused by Staphylococcus aureus, Gram-negative bacilli (such as Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa), and Enterobacteriaceae.

Differences in the risk of antibiotic resistance:

• CABM is less likely to be caused by antibiotic-resistant organisms than HAM. This is because HAM patients are more likely to have been exposed to antibiotics in the recent past.

Differences in the severity of illness:

• HAM patients are often more severely ill than CABM patients. This is because HAM patients often have underlying medical conditions and are more likely to have been exposed to multiple different organisms.

Empiric pharmacological therapy for CABM:

• The recommended empiric pharmacological therapy for CABM in adults is a third-generation cephalosporin, such as ceftriaxone or cefotaxime.
• For patients with penicillin allergy, vancomycin can be used in combination with a third-generation cephalosporin or a fluoroquinolone, such as levofloxacin or moxifloxacin.

Empiric pharmacological therapy for HAM:

• The recommended empiric pharmacological therapy for HAM in adults is a combination of vancomycin and a third-generation cephalosporin.
• For patients with penicillin allergy, vancomycin can be used in combination with a fluoroquinolone and an aminoglycoside, such as gentamicin or tobramycin.

Rationale for the differences in empiric pharmacological therapy:

The empiric pharmacological therapy for HAM is more broad-spectrum than the empiric pharmacological therapy for CABM to cover the wider range of potential causative organisms, including antibiotic-resistant organisms.

Additionally, HAM patients are often more severely ill and require more aggressive antibiotic therapy.

N-S: You are admitting a 78-year-old male smoker with hx of asthma into the intensive care unit for a diagnosis of hospital acquired pneumonia. He was admitted three weeks ago with pneumonia and discharged to home on azithromycin after a 2-day hospitalization. What antimicrobial treatment will you order on his ICU admission now? Explain your rationale.

I would order empiric antimicrobial therapy with vancomycin and a third-generation cephalosporin, such as ceftriaxone or cefotaxime.

Rationale:

• The patient is at high risk for hospital-acquired pneumonia (HAP) due to his age, smoking status, and history of asthma.
• HAP is more likely to be caused by antibiotic-resistant organisms, such as Staphylococcus aureus and Pseudomonas aeruginosa.
• The patient was recently hospitalized and received azithromycin, which may have selected for antibiotic-resistant organisms.
• Vancomycin and a third-generation cephalosporin are a broad-spectrum combination that will cover the most likely causative organisms of HAP.

T-Z: What would be the alternative empiric pharmacological therapy for a 50-year-old male with a history of anaphylaxis to cephalosporins?

I would order empiric antimicrobial therapy with vancomycin and a fluoroquinolone, such as levofloxacin or moxifloxacin.

Rationale:

• Fluoroquinolones are a broad-spectrum class of antibiotics that are effective against a wide range of bacteria, including those that are resistant to cephalosporins.
• Fluoroquinolones are generally safe and well-tolerated, but they can cause serious side effects, such as seizures and tendinitis.
• The patient's history of anaphylaxis to cephalosporins is a relative contraindication to the use of cephalosporins. However, the benefits of empiric antimicrobial therapy with vancomycin and a fluoroquinolone outweigh the risks in this case.

Additionally, I would consult with an infectious disease specialist to discuss the best empiric antimicrobial therapy for this patient.

Other considerations when choosing the appropriate antibiotic for a patient with septic shock:

• The severity of the patient's illness: More severely ill patients may require more aggressive antibiotic therapy.
• The patient's underlying medical conditions: Patients with underlying medical conditions, such as diabetes and chronic kidney disease, may be at increased risk for certain infections and may require specific antibiotic therapy.
• The patient's allergies: Patients with allergies to certain antibiotics may need to be treated with alternative antibiotics.

**It is important to note that empiric antibiotic therapy is a best guess at the best antibiotic