Clarithromycin efficacy against Legionella?

Can the Legionella bacterium survive in the lung even after a three week course of Clarithromycin (500mg) taken twice daily, and can it then re-infect the patient about two months later?

It is unlikely that Legionella could survive 3 weeks of clarithromycin if you responded within the first 5 days. Was the Legionnaires’ disease confirmed by a Legionella test ordered by a physician? If so, what is the name of the test?

Re-infection by Legionella is theoretically possible, but we have only seen one convincing case.


Here’s the timeline of my Legionella infection and my patient history. I’m a 60 yr old male recently retired carpenter, so I am fairly fit. There was an outbreak of Legionnaires’ here in Edinburgh Scotland, UK, in May 2012 which took three lives and hospitalized ~50.

I first had symptoms on May 5th which I thought was the flu. It rapidly progressed into high fever with vomiting and diarrhea. After three days, I was too wiped out and confused to seek medical help so I tried to battle through it.

On June 7, I was well enough to visit my doctor who sent me to the hospital where a blood sample was tested. I also had a chest x-ray. The blood sample was positive for Legionella, and I was given Clarithromycin (500mg).

About two weeks of being off my antibiotics, I began having symptoms of Legionnaires’. I had lower leg pain, headaches, a bit of diarrhea, and was coughing up phlegm. This only lasted a couple of days and I got back to normal.

A week later I gave a blood sample for my Legionella follow-up survey. My doctor called to say the sample was positive for Legionella and put me on a seven day course of Clarithromycin (500mg) again. I went for a chest x-ray where it was confirmed I had an infection of the lower lung. This is why I asked if it was possible to carry the Legionella bacteria after antibiotic treatment. I’m due to give another blood sample and I will await the results with interest.


The more important test is comparison of your next chest X-ray with the chest X-ray of 20/07/12. Your next chest X-ray may be abnormal for the next 2 – 3 months, but it should not be worse. If your fever has subsided, you are probably recovering.

Your Legionella blood test may remain abnormal for many more months, but that is not of concern – this test shows you contracted Legionnaires’ disease, but it is not that useful for measuring outcome.

Although the NHS maintains that cooling towers are a primary source, the actual source is the drinking water, and for reasons unclear, UK health officials rarely will admit to this likely possibility and therefore classify the source as unknown.

The following articles may be of interest to your physicians and can be downloaded from the Publications section.

Cooling towers and Legionellosis: A conundrum with proposed solutions

Legionnaires’ disease Contracted from Patient Homes: The Coming of the Third Plague?