Paeds SAQs · infectious-diseases
Device-associated and healthcare-associated infection — formative SAQs
Two MedVellum formative short-answer questions on device-associated and healthcare-associated infection in children, covering NHSN surveillance definitions, the multimodal prevention bundle, source control by device removal, antimicrobial de-escalation, and an outbreak scenario on a neonatal unit. The marks and timing support transparent self-assessment; they are not an official board format or pass standard.
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Target exams
SAQ 1 — A school-age child with a suspected central-line infection
Question 1 — 10 formative marks; suggested time 15 minutes [3]
A previously well 8-year-old girl with a short-bowel syndrome is six days into an admission for a line-related course of antibiotics. She has a tunneled central venous catheter for parenteral nutrition. She spikes a fever with rigors during a line flush, looks unwell, and the exit site is clean with no tunnel erythema. Blood pressure and perfusion are normal. [1] [3]
- Define the surveillance syndrome she may have and state the time and device criteria that place it in the device-associated category. (2 marks)
- Outline your immediate investigations and empiric management, including your decision on the line. (3 marks)
- State the prevention bundle that should have been in place, and name the single greatest modifiable risk factor. (3 marks)
- Two days later Staphylococcus aureus grows in both the line and peripheral cultures. What changes about your management and why? (2 marks)
Full-credit answer — SAQ 1
Reveal full-credit answer for SAQ 1
1. Surveillance syndrome and criteria
She may have a central-line-associated bloodstream infection (CLABSI): a laboratory-confirmed bloodstream infection in a patient with a central line in place for more than two calendar days, where the infection is not attributed to another site. The healthcare-associated time convention is onset more than 48 hours after admission, and she is well beyond both thresholds. I would count her against the unit's line-days denominator, but I would treat her on clinical grounds immediately rather than wait for surveillance adjudication. [3] [12]
2. Investigations, empiric therapy and the line decision
I would draw paired blood cultures from a peripheral site and from the line before antibiotics, and send a full blood count, C-reactive protein, electrolytes, renal and liver function, and a lactate. Because she is well perfused and not septic, I would start empiric antistaphylococcal cover for coagulase-negative staphylococci and Staphylococcus aureus, broadened per local guidance. Because the site is clean and she is clinically stable, immediate line removal is not mandated on the first positive culture, but I would set a clear threshold: remove the line if she develops sepsis, a tunnel or pocket infection, persisting or relapsing bacteraemia, or a resistant or high-risk organism. [3] [12]
3. Prevention bundle and the key risk factor
The bundle that should have been in place is multimodal: hand hygiene at the five moments, maximal sterile barriers at insertion, chlorhexidine skin preparation, optimal site selection, scrub-the-hub before every access, intact dressing care, and daily documented review of line necessity. The single greatest modifiable risk factor is the device itself, so the most reliable prevention is removing the line as soon as it is no longer essential. [3] [12]
4. Staphylococcus aureus changes the line decision
Staphylococcus aureus bacteraemia from a line is a high-risk organism with a strong tendency to seed distant foci, so the line should be removed, the child imaged for endocarditis and metastatic infection with echocardiography and targeted imaging, and therapy extended and guided by infectious diseases. This is one of the organisms for which line salvage is not appropriate. [3] [12]
Marking grid — SAQ 1
| Domain | Full-credit requirements | Marks |
|---|---|---|
| Surveillance definition | CLABSI with correct time (>48 h) and device (>2 day) criteria | 2 |
| Investigations and empiric therapy | Paired cultures before antibiotics; antistaphylococcal empiric cover; stated line-removal threshold | 3 |
| Prevention bundle and risk factor | Hand hygiene, barriers, chlorhexidine, hub care, daily review; device dwell as key risk | 3 |
| S. aureus management | Remove line; image for distant foci; prolonged guided therapy | 2 |
Common pitfalls — SAQ 1
- Treating the surveillance definition as the trigger for clinical action, delaying cultures and antibiotics.
- Salvaging a line in Staphylococcus aureus bacteraemia, or attributing a single positive culture to contamination without the clinical context.
- Naming only one bundle element rather than the multimodal bundle, or omitting the daily review of necessity. [3] [12]
SAQ 2 — A cluster of CLABSI on the neonatal unit
Question 2 — 10 formative marks; suggested time 15 minutes [1]
Over four weeks your neonatal intensive care unit records three new central-line-associated bloodstream infections, double the unit's usual rate. The organisms are coagulase-negative staphylococci in two and a Klebsiella in one. [1] [2]
- Define what makes this an outbreak and state the denominator you would use to assess it. (2 marks)
- Outline your outbreak investigation, including the bundle elements you would review. (4 marks)
- Explain how antimicrobial stewardship and device stewardship interact on the unit, and why both matter for the resistant organism. (2 marks)
- State two equity or special-population considerations for this unit. (2 marks)
Full-credit answer — SAQ 2
Reveal full-credit answer for SAQ 2
1. Outbreak definition and denominator
An outbreak is an infection rate above the unit's baseline or expected number of cases over a defined period. The denominator is line-days, so the rate is cases per 1000 central-line-days, not a raw count. I would confirm each case against the current NHSN definition before declaring the cluster, then calculate the rate against the unit's historical baseline. [1] [12]
2. Outbreak investigation and bundle review
I would convene the infection-prevention team, confirm the case definition, calculate the rate per 1000 line-days, and look for a common organism and a common failure. With coagulase-negative staphylococci predominating I would review insertion and access technique: hand hygiene compliance, maximal sterile barriers, chlorhexidine preparation, scrub-the-hub before access, dressing integrity, and daily documented review of line necessity. For the Klebsiella I would additionally review environmental and feeding-related sources, molecular typing to confirm relatedness, and cohorting if a common strain is found. I would feed the rate and the findings back to staff and sustain the audit, because outbreaks recur where surveillance lapses. [1] [2] [12]
3. Stewardship of devices and antimicrobials
The two stewardships are inseparable. Every additional line-day selects for biofilm-forming organisms, and every broad-spectrum antibiotic-day selects for resistant flora such as the Klebsiella. So I would narrow and shorten antimicrobials to the organism and remove lines as early as possible, reviewing both daily. The resistant organism is the predictable product of weak stewardship of both the device and the drug. [2] [12]
4. Equity and special-population considerations
First, the burden of device-associated infection falls on the smallest and sickest: very low birth weight neonates and complex-chronic children carry the highest risk and the most line-days. Second, indigenous and disadvantaged families experience avoidable nosocomial harm inequitably, so culturally safe care and clear communication with families matter. The unit should track these outcomes and ensure prevention reaches the children at greatest risk. [1] [2]
Marking grid — SAQ 2
| Domain | Full-credit requirements | Marks |
|---|---|---|
| Outbreak and denominator | Rate above baseline; cases per 1000 line-days | 2 |
| Investigation and bundle | Case confirmation, rate, common-organism review, full bundle audit, feedback | 4 |
| Dual stewardship | Device-day and antibiotic-day both drive resistance; narrow and remove | 2 |
| Equity and special populations | Neonatal and complex-chronic burden; indigenous and disadvantaged inequity | 2 |
Common pitfalls — SAQ 2
- Counting raw cases without the line-day denominator, so the rate is uninterpretable.
- Reviewing only one bundle element, or omitting the feeding and environmental review when a Gram-negative is involved.
- Treating antimicrobial stewardship as separate from device stewardship. [2] [12]
References
- [1]Hsu, H E; Mathew, R; Wang, R Health Care-Associated Infections Among Critically Ill Children in the US, 2013-2018. JAMA pediatrics, 2020.PMID 33017011
- [2]Weiner-Lastinger, L M; Abner, S; Benin, A L Antimicrobial-resistant pathogens associated with pediatric healthcare-associated infections: Summary of data reported to the National Healthcare Safety Network, 2015-2017. Infection control and hospital epidemiology, 2020.PMID 31762428
- [3]O'Grady, N P; Alexander, M; Burns, L A Guidelines for the prevention of intravascular catheter-related infections. American journal of infection control, 2011.PMID 21511081
- [4]Miller, M R; Griswold, M; Harris, J M 2nd Decreasing PICU catheter-associated bloodstream infections: NACHRI's quality transformation efforts. Pediatrics, 2010.PMID 20064860
- [9]McDonald, L C; Gerding, D N; Johnson, S Clinical Practice Guidelines for Clostridium difficile Infection in Adults and Children: 2017 Update by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA). Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 2018.PMID 29562266
- [12]Yokoe, D S; Anderson, D J; Berenholtz, S M A compendium of strategies to prevent healthcare-associated infections in acute care hospitals: 2014 updates. Infection control and hospital epidemiology, 2014.PMID 25026611