How do you manage bacterial infections?

Management of Bacterial Infections

Start empiric broad-spectrum antibiotics immediately in critically ill patients with suspected bacterial infection, then narrow therapy based on culture results and clinical response. 1

Initial Assessment and Source Identification

Identify the infection source urgently to guide both antimicrobial selection and source control interventions:

• Evaluate for intravascular catheter infections by obtaining blood cultures from both the catheter and a peripheral site; a differential time to positivity (DTTP) ≥2 hours indicates catheter-related bacteremia 2
• Assess for intra-abdominal infections, surgical site infections, urinary tract sources, and skin/soft tissue involvement 2
• Obtain cultures before starting antibiotics in severe infections to guide definitive therapy 3

Empiric Antimicrobial Therapy

For Gram-Negative Suspected Infections

Use monotherapy with an anti-pseudomonal cephalosporin or carbapenem for most patients with suspected gram-negative bacteremia 2

• In critically ill patients with suspected multidrug-resistant (MDR) gram-negative pathogens, initiate two antimicrobial agents of different classes, then de-escalate to single-agent therapy once susceptibilities are available 2

For Gram-Positive Suspected Infections

Include vancomycin or daptomycin when MRSA is a concern based on local epidemiology or patient risk factors 2

For Skin and Soft Tissue Infections

• For mild cellulitis without MRSA risk: Use oral beta-lactams (penicillinase-resistant penicillins or cephalosporins) in areas where community-acquired MRSA (CA-MRSA) is not prevalent 1
• For severe cellulitis or MRSA suspected: Use parenteral glycopeptides or newer antimicrobials 1
• For simple abscesses: Incision and drainage alone is sufficient without antibiotics if there is no surrounding cellulitis or systemic signs 1
• For complex abscesses (perianal, perirectal, IV drug injection sites): Perform incision and drainage plus broad-spectrum antibiotics covering gram-positive, gram-negative, and anaerobic bacteria if systemic signs present, patient immunocompromised, or source control incomplete 1

For Intra-Abdominal Infections

In critically ill patients with hospital-acquired intra-abdominal infections (HA-IAIs), recognize that post-operative peritonitis carries high mortality and MDR risk; use of broad-spectrum antibiotics between initial intervention and reoperation significantly increases MDRO emergence 1

Pharmacokinetic Optimization in Critical Illness

Administer higher than standard loading doses of hydrophilic antimicrobials (beta-lactams) in critically ill patients due to increased volume of distribution from sepsis-related fluid shifts 1

• For time-dependent antibiotics (beta-lactams): Use multiple daily dosing or continuous infusion to maintain plasma concentrations above the MIC throughout the dosing interval 1
• For concentration-dependent antibiotics (aminoglycosides, fluoroquinolones): Ensure adequate peak concentrations relative to the MIC 1

Source Control

Remove infected intravascular catheters in the following situations 2:

• Tunnel infections or pocket infections
• Persistent bacteremia despite adequate treatment
• S. aureus catheter infections (generally recommended)
• Candidemia
• Atypical mycobacterial infection

For anorectal abscesses, drain surgically promptly as undrained abscesses can expand into adjacent spaces and progress to systemic infection 1

Duration of Therapy

For S. aureus Bacteremia 2:

• Uncomplicated bacteremia: Minimum 2 weeks
• Complicated bacteremia: 4-6 weeks
• Infective endocarditis: 6 weeks

For Skin and Soft Tissue Infections 3:

• Non-complicated cases: 5-10 days
• Severe or complicated infections: 7-14 days

Obtain repeat blood cultures 2-4 days after initial positive cultures to document clearance of bacteremia 2

Special Populations

Neutropenic Patients with Fever

Admit high-risk neutropenic patients and start broad-spectrum IV antibiotics immediately; low-risk cases may be considered for early discharge once clinically stable 2

Immunocompromised Patients

Exercise caution with oral beta-lactam step-down therapy in immunocompromised patients 4

Infection Control Measures for MDR Organisms

Hand Hygiene

Implement rigorous hand hygiene programs using alcohol-based hand rubs before and after all patient contacts; monitor compliance and provide feedback to healthcare workers 1

Contact Precautions

Use contact precautions (gloves and gowns) for all patient encounters with ESBL-producing Enterobacteriaceae, MDR-Acinetobacter baumannii, and other MDR gram-negative bacteria 1

Active Screening Cultures

Perform active screening cultures at hospital admission for high-risk patients or all patients in high-risk units (ICU, cancer wards) using rectal/perirectal swabs, inguinal area samples, and samples from manipulated sites 1

Environmental Cleaning

Monitor and audit environmental cleaning performance with protocols specifying which items to disinfect, which disinfectants to use, and frequency of disinfection 1

Antimicrobial Stewardship

Implement antimicrobial stewardship programs to limit use of specific antimicrobial agents based on patient comorbidities and local resistance patterns 1

Critical Pitfalls to Avoid

• Do not delay antibiotic administration in critically ill patients with sepsis or organ dysfunction; start empiric therapy immediately 1
• Avoid prolonged broad-spectrum antibiotics between surgical interventions in post-operative peritonitis, as this significantly increases MDRO risk 1
• Do not use antibiotics for >5 days before diagnosing anastomotic leakage in colorectal surgery patients, as this is an independent risk factor for MDRO acquisition 1
• Never use rifampicin as monotherapy or adjunctive therapy for skin and soft tissue infections 3
• Do not delay surgical drainage in purulent infections; drainage is fundamental for effective treatment 3
• Avoid continuing antibiotics until all symptoms resolve; follow evidence-based duration recommendations to prevent unnecessary antibiotic exposure 2
• Do not fail to recognize complicated infections requiring longer treatment durations (e.g., S. aureus bacteremia with metastatic foci) 2

Monitoring and Follow-up

Perform transthoracic echocardiography in all patients with S. aureus bacteremia to evaluate for endocarditis 2

Repeat imaging studies in patients with persistent bacteremia to identify undrained infection foci 3