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MI10.1-5 | Healthcare-Associated Infections — PBL Case

CLINICAL SETTING

Shri Balaji Children's Hospital is a 120-bed private hospital in Hyderabad with a 10-bedded Paediatric Intensive Care Unit (PICU). Over a 6-week period in February–March, the HICC receives reports of five blood culture-positive episodes across four PICU patients, all involving central venous catheters (CVCs). All five isolates are Klebsiella pneumoniae. Three are resistant to third-generation cephalosporins and carbapenems (confirmed carbapenemase producers by mCIM test), and one is additionally resistant to colistin. The PICU team is alarmed. Dr. Ananya Krishnamurthy, the infection control officer, activates an outbreak investigation. You are a Year-2 MBBS student observing the HICC outbreak response team.

Trigger 1: The Cluster is Recognised

Dr. Krishnamurthy presents the line-listing to the team: Patient 1 (7-month-old, post-cardiac surgery, CVC day 6) — blood culture positive for K. pneumoniae ESBL on day 8 of admission; Patient 2 (2-year-old, septic shock, CVC day 4) — K. pneumoniae KPC on day 6; Patient 3 (9-month-old, bronchiolitis on CPAP, CVC day 3) — K. pneumoniae KPC on day 5; Patient 4 (4-year-old, head injury, CVC day 7) — K. pneumoniae KPC-colistin resistant on day 9. All CVCs were inserted by different junior residents. Catheter dwell times range from 3 to 7 days. All patients received pre-procedure antibiotic prophylaxis. Hand hygiene compliance audit for the PICU shows 38% adherence to Moment 2 ('Before aseptic procedure'). Environmental swabs of CVC trolleys grow K. pneumoniae in 2 of 5 samples.

DISCUSSION POINTS

  • Using the chain of HAI transmission, identify the most likely reservoir, mode of transmission, and portal of entry for these CLABSI cases. What evidence in the line-listing supports your hypothesis?
  • The hand hygiene compliance for Moment 2 is 38%. Why is Moment 2 specifically the most critical WHO moment to target in a CLABSI prevention context? What does the environmental swab result suggest about the reservoir?
  • What does the presence of both ESBL-producing and KPC-producing K. pneumoniae in the same unit suggest about the evolutionary pressures and horizontal gene transfer occurring in this PICU?
Click to reveal Trigger 2: The Root Cause Investigation (discuss previous trigger first!)

Trigger 2: The Root Cause Investigation

The HICC conducts a structured root cause analysis. Direct observation reveals: (a) Residents inserting CVCs use a non-sterile trolley with betadine but no chlorhexidine; (b) CVC dressing changes are performed without gown and face shield in 4 of 6 observed cases; (c) The CVC insertion bundle checklist exists but is completed retrospectively in 3 of 5 cases; (d) A nurse notes that alcohol-based hand rub dispensers near CVC trolleys were found empty for at least 3 consecutive days. Whole-genome sequencing of all five isolates reveals that isolates from Patients 2, 3, and 4 share a clonal lineage (ST258 K. pneumoniae) carrying blaKPC-2 on an IncFII plasmid. Patient 4's isolate additionally carries the mcr-1 gene on a separate plasmid, conferring colistin resistance.

DISCUSSION POINTS

  • From the root cause analysis findings, identify the THREE most critical system failures that directly enabled CLABSI transmission in this PICU. Use the hierarchy of controls framework (elimination, substitution, engineering, administrative, PPE) to categorise each failure.
  • The ST258 clone carrying blaKPC-2 on an IncFII plasmid is found in three patients. Explain the mechanism by which this plasmid could spread within the PICU even without direct patient-to-patient contact. Why is the emergence of mcr-1 in Patient 4's isolate a sentinel event?
  • The CVC bundle checklist was completed retrospectively. What does this indicate about institutional safety culture, and how does this connect to the HICC's role in HAI prevention beyond surveillance?
Click to reveal Trigger 3: Control Measures and Outcome (discuss previous trigger first!)

Trigger 3: Control Measures and Outcome

The HICC implements the following interventions: CLABSI bundle retraining with direct observation assessment; replacement of betadine with 2% chlorhexidine gluconate in 70% isopropyl alcohol as the skin antiseptic for CVC insertion; daily 'CLABSI rounds' by the infection control nurse with real-time checklist verification; CVC trolley decontamination protocol using sodium hypochlorite wipes; contact precautions (gown + gloves + single-bed cohorting) for all KPC-positive patients; hand hygiene dispensers restocked daily with weekly stock checks logged. At 4 weeks, a repeat environmental swab is negative. Hand hygiene Moment 2 compliance rises to 79%. No new CLABSI cases in 6 weeks. However, the colistin-resistant isolate from Patient 4 prompts a policy question: should the hospital implement active surveillance cultures (rectal swabs for CPE screening) for all PICU admissions?

DISCUSSION POINTS

  • The bundle intervention replaced betadine with 2% chlorhexidine gluconate for CVC skin antisepsis. What is the microbiological basis for chlorhexidine being preferred over betadine for this indication? What is the principle of residual activity?
  • For the KPC-positive patients, contact precautions are implemented. Design the complete standard operating procedure for contact precautions in this PICU, including donning/doffing sequence, dedicated equipment requirements, and visitor restrictions.
  • Evaluate the proposal for active surveillance cultures (rectal swabs for CPE screening) for all PICU admissions. What are the arguments for and against routine active surveillance? What is the significance of detecting CPE colonisation versus infection?

Group Task Assignments

Group 1: HAI Classification, Chain of Transmission & ESKAPE Pathogens

  • Prepare a visual chain-of-transmission diagram for this CLABSI outbreak, annotating each link with the specific evidence from the case and identifying where the chain was (and was not) broken.
  • Summarise the ESKAPE priority pathogen framework and explain why ST258 KPC-producing K. pneumoniae is a WHO critical-priority organism in Indian PICU settings.

Competencies: MI10.1, MI10.5

Group 2: CLABSI Bundle & Standard/Transmission-Based Precautions

  • Create a poster-format CLABSI insertion bundle checklist suitable for display at the PICU CVC trolley, including all 5 evidence-based bundle elements with the rationale for each.
  • Role-play the correct donning-and-doffing of contact precautions PPE (gown, gloves, mask, eye protection) and identify the two most critical error points in the doffing sequence.

Competencies: MI10.2, MI10.3

Group 3: Environmental Surveillance & Antimicrobial Resistance Mechanisms

  • Design a post-outbreak environmental surveillance protocol for the PICU CVC trolleys: specify the method, swab sites, frequency, thresholds, and action plan for positive results.
  • Construct a comparison table of MRSA (mecA/PBP2a), KPC-K. pneumoniae (blaKPC/IncFII plasmid), and NDM-1 (blaNDM) — covering gene location, mechanism, spread potential, and treatment options.

Competencies: MI10.4, MI10.5

Learning Issues

Research these questions and bring your findings to the discussion.

  1. [MI10.1] What is the CDC definition of CLABSI and how does it differ from catheter-related bloodstream infection (CRBSI)? What are the most common causative organisms in Indian PICU settings?
  2. [MI10.1] How does catheter dwell time influence the risk of CLABSI? What is the evidence for scheduled versus as-needed catheter replacement?
  3. [MI10.2] What are the five elements of the evidence-based CLABSI prevention bundle and what is the evidence level (Grade) for each element?
  4. [MI10.2] How does the HICC's role extend beyond surveillance to include system-level safety culture change? What metrics should an HICC track in a PICU?
  5. [MI10.3] What is the correct donning-and-doffing sequence for contact precautions, and what are the most common doffing errors that lead to self-contamination?
  6. [MI10.3] Why is 2% chlorhexidine gluconate in 70% isopropyl alcohol preferred over betadine for CVC insertion site antisepsis? What is the concept of residual antimicrobial activity?
  7. [MI10.4] What sampling methods are used for microbial surface surveillance in healthcare settings (e.g., RODAC plates, swab-contact method)? What colony count thresholds indicate unacceptable contamination?
  8. [MI10.5] What is the mechanism of plasmid-mediated horizontal gene transfer (conjugation via IncFII plasmids) that explains the spread of blaKPC-2 in this outbreak?
  9. [MI10.5] What is the significance of mcr-1 conferring colistin resistance? Why is colistin considered a 'last-resort' antibiotic and what are the implications of resistance to it in a PICU setting?