Legionella are aerobic gram-negative bacilli that reside in association with amoeba in natural water sources, such as lakes and rivers, and multiply in the stagnant, warm water discovered in pipes systems, ac system, and public health spas.

Legionellosis is an umbrella term that includes both Pontiac fever and legionnaires’ illness: the previous is the milder of the 2 diseases, with a self-limited trajectory within 2-5 days of sign start; on the other hand, the latter manifests as bacterial pneumonia.

Legionnaires’ illness is an irregular reason for community-acquired pneumonia and represent around 4% of all brand-new medical diagnoses of pneumonia.

In Canada, less than 100 cases of legionnaires’ illness are reported each year, however owing to diagnostic difficulties, cases are most likely under-reported.

It happens more often throughout durations of warm weather condition (late summer season to early fall in North America).

Threat aspects consist of age older than 40 years, smoking cigarettes, alcohol intake, persistent lung illness, persistent kidney illness, diabetes, immunocompromise, and current travel.

Legionella infection represents a public health danger owing to its capability to spread out through direct exposure to natural water bodies and human-made water tanks,” stated Dr. Ashley Bryson, an internal medication local at the University of Manitoba.

In their brand-new paper, Dr. Bryson and coworkers explained their 77-year-old client who had actually taken a trip to Iowa 2 weeks prior, where he remained in a single-family city home and swam in a regional lake.

Over 4 days of increasing weak point integrated with fever, cough, and repeating abrupt falls in his home, he went to the emergency situation department.

Offered his travel activity, clinicians believed legionnaires’ illness after preliminary basic antibiotic treatment stopped working to treat his pneumonia.

“After evaluation of these preliminary outcomes, we bought bronchoalveolar lavage culture for Legionella spp. and urinary antigen screening,” the scientists stated.

Legionella screening was at first declined by the lab owing to lack of medical validation on the test appropriation.”

“This checkpoint was carried out at our medical website to suppress abuse of Legionella screening in clients without any threat aspects for legionnaires’ illness.”

“After more extensive interaction in between the clinicians and the medical microbiologists relating to the epidemiologic factors to consider of current travel, extended direct exposure to stagnant water, and continuous pneumonia in spite of using broad-spectrum prescription antibiotics, Legionella-particular screening was carried out.”

“Our client’s urinary antigen screening was favorable, yet his bronchoalveolar lavage culture was eventually unfavorable for Legionella spp.”

“We assume that this unfavorable outcome was because of a current dosage of azithromycin, along with other preanalytical elements such as moderate illness concern, bad sample quality, and tasting predisposition throughout bronchoscopy.”

“Given these findings, Legionella pneumonia was believed, and the transmittable illness service was sought advice from.”

The authors recommended levofloxacin 750 mg orally for 10 days, and the client was released on the 4th day of this course, as he no longer needed extra oxygen.

They assumed that their client represents an erratic case of legionnaires’ illness contracted while swimming in Iowa.

“Clinicians ought to think about legionnaires’ illness in clients with pneumonia that does not enhance in spite of using broad-spectrum prescription antibiotics, particularly if the pneumonia is extreme, taking place in immunocompromised clients or clients with current travel history, or when just antimicrobials without activity versus irregular pathogens have actually been administered,” they concluded.

“In addition to the gold requirement of bronchoalveolar lavage culture for medical diagnosis of legionnaires’ illness, urinary antigen screening is a noninvasive test that might help with medical diagnosis.”

Their paper was released in the today’s concern of the Canadian Medical Association Journal

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Ashley Bryson et al2025. Legionnaires’ illness following lake swimming in Iowa. CMAJ 197 (6 ): E155-E158; doi: 10.1503/ cmaj.241086