A 62-year-old renal transplant recipient, hospitalised for 8 days on a general ward, develops fever, cough, relative bradycardia, hyponatraemia and raised serum LDH. Urinary antigen testing is positive for Legionella pneumophila serogroup 1 and two other patients on adjacent wards had similar illnesses last month. Which reservoir is the most likely source of this nosocomial transmission?
- A Respiratory therapy nebuliser reservoirs
- B Fresh flowers and potted plants at the nurses' station
- C The hospital potable water distribution system, with amplification in amoebae within plumbing biofilms ✓
- D Contaminated parenteral nutrition fluid
Correct answer: C. The hospital potable water distribution system, with amplification in amoebae within plumbing biofilms
Explanation
Hospital-acquired legionellosis almost always arises from the building water system, where Legionella survives and multiplies inside protozoa within pipe biofilms and is aerosolised from showers and taps. Control involves heating and flushing or hyperchlorination of the water supply. Cooling towers cause community outbreaks rather than clustered ward infections, and nebulisers, plants and infusates are not established Legionella reservoirs. Culture requires buffered charcoal yeast extract agar.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.