Key Facts

HAIs represent a major burden on the NHS in terms of patient harm, mortality, and cost. Many are preventable through evidence-based infection prevention measures and antimicrobial stewardship.

Epidemiology

• ~300,000 HAIs/year in England
• HAI prevalence: 6.4% (PPS 2016)
• Attributable mortality: ~5,000 deaths/year in England
• MRSA bacteraemia: ~780/year (down from 7,000+ in 2007)
• C. difficile: ~13,000/year (down from 55,000 in 2007)
• E. coli bacteraemia: ~40,000/year (most common Gram-negative BSI — urinary source most common)

Aetiology

Common HAIs:

• Catheter-associated UTI (CAUTI): E. coli, Klebsiella, Enterococcus, Candida
• Central line-associated bloodstream infection (CLABSI): coag-neg staph, S. aureus, Enterococcus, Gram-negatives
• Ventilator-associated pneumonia (VAP): Pseudomonas, S. aureus, Acinetobacter, Gram-negatives
• Surgical site infection (SSI): S. aureus, coag-neg staph, Gram-negatives
• C. difficile infection: antibiotic-associated

Pathophysiology

• Healthcare devices (catheters, lines, ventilators) bypass natural defence barriers → bacterial colonisation → biofilm formation → infection
• Hospital environment: reservoirs of resistant organisms (MRSA, VRE, CPE, C. difficile spores)
• Host factors: immunosuppression, extremes of age, invasive procedures, prolonged hospitalisation
• Antibiotic pressure: selects for resistant organisms; disrupts normal microbiome

CAUTI

• Fever, dysuria, suprapubic pain, cloudy/offensive urine
• Catheterised patient — symptoms may be non-specific (confusion in elderly)

CLABSI

• Fever, rigors, especially during/after line use
• Erythema at exit site, purulent discharge
• Positive blood cultures with organism typical of line infection

VAP

• New/worsening fever, purulent secretions, new infiltrate on CXR
• Developing ≥48 hours after intubation

SSI

• Wound erythema, warmth, discharge, dehiscence
• Within 30 days of surgery (or 1 year if implant)

Red Flags

• Sepsis signs in any hospitalised patient with device
• Positive blood cultures for typical healthcare-associated organism
• New onset CDI diarrhoea during or after hospital admission
• Multi-drug resistant organism identified

General Approach

• Blood cultures: before antibiotics if HAI suspected
• Specific site cultures: urine (MSU/CSU), wound swab, sputum/BAL, line tip
• FBC, CRP, procalcitonin: infection markers
• Imaging: CXR (pneumonia), USS/CT (abscess/collection)

Surveillance

• Mandatory reporting to UKHSA: MRSA, MSSA, E. coli, Klebsiella, Pseudomonas bacteraemia; C. difficile
• SSI surveillance: optional but recommended for orthopaedic, cardiac, and other high-risk surgery
• Point prevalence surveys: periodic assessment of HAI rates

Special Tests

• MRSA screening: nasal ± groin swab on admission
• CPE screening: rectal swab for high-risk patients (travel, ICU transfer)
• C. difficile toxin: loose stool only

Non-pharmacological — Prevention

Hand hygiene (WHO 5 Moments):

1. Before patient contact
2. Before aseptic task
3. After body fluid exposure risk
4. After patient contact
5. After contact with patient surroundings

Device management:

• Urinary catheters: insert only when indicated, review daily, remove as soon as possible; aseptic insertion technique
• Central lines: aseptic insertion (Matching Michigan bundle), daily review of ongoing need, chlorhexidine dressings
• Ventilators: head of bed elevation, daily sedation holds, oral chlorhexidine, subglottic aspiration

Antimicrobial stewardship:

• Review antibiotics at 48–72 hours: stop if no infection, narrow spectrum based on cultures, switch IV to oral
• Restrict high-risk antibiotics (4Cs) — co-amoxiclav, cephalosporins, ciprofloxacin, clindamycin
• Guidelines adherence: local antibiotic guidelines based on resistance patterns

Environmental:

• Enhanced cleaning of patient areas
• Isolation of infected/colonised patients (side rooms)
• Sporicidal cleaning for C. difficile

Pharmacological — Treatment

• Treat specific HAI according to organism and site:
  • CAUTI: per local guidelines (often nitrofurantoin, trimethoprim, or gentamicin based on culture)
  • CLABSI: empirical vancomycin ± gentamicin; definitive based on culture
  • VAP: piperacillin-tazobactam or meropenem ± vancomycin; de-escalate per culture
  • SSI: flucloxacillin (MSSA) or vancomycin (MRSA); Gram-negative cover if abdominal
  • CDI: oral vancomycin per NICE NG199

Referral Criteria

• Infection prevention and control team: all HAIs
• Microbiology: resistant organisms, complex infections
• Antimicrobial stewardship team: review of antibiotic use
• Surgery: SSI requiring wound management or debridement

• HAIs increase hospital stay by an average of 5–10 days
• Attributable mortality: varies by infection type — CLABSI ~12–25%, VAP ~13%, CDI ~5–15%
• NHS cost: £1–2 billion/year
• UK programmes have achieved >80% reduction in MRSA bacteraemia and >50% reduction in CDI since 2007
• E. coli bacteraemia: remains a challenge — ambition to reduce by 50%
• Prevention is far more effective than treatment — most HAIs are preventable

Mandatory Reporting Organisms (UKHSA)

High Impact Interventions (Care Bundles)