Legionella outbreak

Question 1

describe the microscope findings of Legionella

what does this bug require for growth?

Answer 1

it is a gram neg, rod shaped

this bug requires iron salts and L-cysteine for growth.

Question 2

where is legionella found?

is there any other species that are particular for QLD?

Answer 2

it is found in soil and fresh water, particularly lakes, rivers, streams, mud and thermal pools

L. longbeachiae is found in potting mix

Question 3

how do we catch legionella?

Answer 3

it is from inhalation of aerosols/aspiration

these aerosols can survive whilst drifting up to 3km!

Question 4

what are the infectious syndromes of legionella?

Answer 4

1. severe pneumonia - Legionnaire’s disease - mostly legionella pneumophilia 1
2. pontiac fever - mild, febrile URTI

Question 5

how do we test for legionella?

Answer 5

urinary antigen detection is good, but it only tests for L. pneumophilia serogroup 1. Not Lp 2-14 and not longbeachiae

it is pretty quick and pretty sensitive.

a better test is PCR on a sputum/BAL

usually, however, we do serology - but this is not great because there can be a huge delay! may take weeks