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Nosocomial Legionella Water System — SCE Infectious Diseases MCQ

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HardInfection Prevention & ControlNosocomial Legionella Water SystemSCE Infectious Diseases

Two postoperative patients on the same ward develop Legionella pneumophila serogroup 1 pneumonia. Environmental sampling detects an indistinguishable strain in the ward hot-water return. Which response is most appropriate?

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Correct answer: CInitiate case finding, source investigation and immediate water-system control measures

The epidemiological link plus a matching environmental isolate requires a coordinated outbreak response: active case finding, clinical and environmental microbiology, water-system risk assessment and immediate control or remediation. Legionella is acquired from contaminated aerosols rather than ordinary person-to-person spread, so negative-pressure isolation and mass antibiotic prophylaxis do not address the source. Waiting for another case risks further exposure.

Reference: UKHSA: Investigation of Legionnaires disease cases, clusters and outbreaks: https://www.gov.uk/government/publications/investigation-of-legionnaires-disease-cases-clusters-and-outbreaks