Hospital-Acquired Infections (HAIs): Types, Symptoms, Prevention & Surveillance

HAIs (nosocomial infections) affect ~7% of hospitalized patients in high-income countries (higher in LMICs). Defined as infection onset ≥48h post-admission (or <48h if incubating at admission).

Major HAI Types (CDC/NHSN)

1. CAUTI (Catheter-associated UTI) – 30–40% of HAIs
2. CLABSI (Central line-associated BSI) – High mortality (12–25%)
3. VAP (Ventilator-associated pneumonia) – ICU hallmark
4. SSI (Surgical site infection) – Superficial, deep, organ/space
5. C. difficile infection – Antibiotic-associated diarrhea
6. MDRO infections: MRSA, VRE, CRE, ESBL

Clinical Presentation by Site

HAI Type	Key Symptoms
CAUTI	Fever, suprapubic pain, cloudy urine, new delirium (elderly)
CLABSI	Fever/chills, hypotension, erythema at site, positive blood cultures
VAP	New infiltrate + fever/leukocytosis + purulent sputum + ↓O2
SSI	Incisional pain, erythema, warmth, purulent drainage, dehiscence
C. diff	Watery diarrhea (≥3/day), abdominal pain, leukocytosis, + toxin assay

Systemic Signs (Any HAI)

• Fever >38.3°C (or <36°C in elderly/septic)
• Tachycardia, hypotension, altered mental status
• Leukocytosis/leukopenia, ↑ bands, ↑ lactate, ↑ procalcitonin

Prevention Bundles (Evidence-Based)

• CAUTI: Avoid catheter; aseptic insertion; closed system; daily necessity review; early removal
• CLABSI: Maximal barrier insertion; chlorhexidine skin prep; daily line review; chlorhexidine dressings
• VAP: HOB 30–45°; daily sedation vacation/SBT; oral care (chlorhexidine); subglottic suction
• SSI: Normothermia, normoglycemia, antibiotic prophylaxis timing, clippers not razors
• Hand hygiene: WHO 5 Moments – single most effective intervention
• Antimicrobial stewardship: De-escalation, duration limits, IV→PO switch

Surveillance & Reporting

NHSN (CDC), ECDC (Europe) standardized definitions enable benchmarking (SIR – Standardized Infection Ratio). Public reporting drives accountability.