Case reports of infections due to microbiologically contaminated water from dental unit waterlines

Reviews about – Case reports of infections due to microbiologically contaminated water from dental unit waterlines

Water splash from dental unit instrument caused painful eye infection with an amoebae, resulting in partly loss of sight

A woman went to the dentist and during treatment, the air rotor handpiece was activated 8 cm from her face and a splash of water landed on her face and her right eye. The water was wiped away and treatment proceeded. After she returned home she started feeling irritation in the right eye, and the next day the pain had increased, and she went to a medical center. The first treatment only provided temporary relief and the condition of her eye worsened over time. One month after the visit at the dentist, the protozoan “Acanthamoeba sp.” was isolated from ocular secretions. Infections with amoeba is difficult to treat and even after 4 years the patient still experienced pain, photophobia and blurred vision and visual acuity in the right eye was 20/200 (with corrected vision).


Barbeau J. Lawsuit against a dentist related to serious ocular infection possibly linked to water from a dental handpiece. JCDA 2007 vol. 73 no. 7 pp. 618-622

Healthy elderly woman died from infection with Legionella from dental unit water

Italian 82-year-old woman was in 2011 hospitalized in extensive care, and diagnosed with legionnaire’s disease (pneumonia caused by Legionella pneumophila). Even though she had no underlying disease and received antibiotic treatment she developed irreversible septic shock and died.

The woman did not have any other obvious possibilities of exposure to Legionella pneumophila during the incubation period (2-10 days) than two appointments at a dental practice. Microbiological investigation of water from tap and shower in the woman’s home, and from the cold tap water and the high-speed turbine at the dental practice, showed that there was not Legionella in the womans home, but Legionella was isolated from the dental practice. Furthermore the genomic pattern of the Legionella pneumophila strain isolated from the woman’s lung was identical to the Legionella pneumophila strain in water from the dental unit waterlines (high-speed turbine).


Ricci M L, Fontana S, Pinci F, Fiumana E, Pedna M F, Farolfi P, Sabattini M A B, and Scaturro M. Pnemonia associated with dental unit waterline. Lancet 2012 vol. 379 pp 684

Health risk for dentists and staff due to Legionella in dental unit waterlines

A Californian elderly dentist died from pneumonic legionellosis. L. dumoffii, L. pneumophila and L. longbeachae were isolated from his lung tissue and the same species were identified in water from the dental unit. Legionella species were also identified in the dentist’s home, however there were >10,000 organisms per ml in the dental unit water and <100 organisms per ml in potable water in the dentist’s home. Studies have shown that dentists and staff at dental clinics have elevated levels of anti- Legionella antibodies compared to the rest of the population, indicating that they are exposed to Legionella at their working environment. Besides pneumonic legionellosis, Legionella species can also cause Pontiac fever, which in symptoms reminds of the seasonal flu, and would rarely be tested for at the practicing doctor. Hence disease caused by Legionella in dental clinics could be highly underestimated.


Atlas R M, Williams F W and Huntington M K. Legionella contamination of dental—unit waters. Applied and Environmental Microbiology 1996 Vol. 61 No. 4 pp. 1208-1213

Szymanska J. Risk of exposure to Legionella in dental practice. Ann Agric Environ Med 2004 vol. 11 pp. 9-12

Immunocompromised man died from infection with Legionella from dental unit water

In Sweden 2013, a 67-years-old man with leukemia died from an infection of Legionella pneumophila serogroup 1 after he had been to a routine investigation at the orthodontic department before scheduled bone marrow transplantation.

In the water from the dental unit 200 CFU/100 ml water of Legionella pneumophila serogroup 1 was detected and serological testing determined that the Legionella strain isolated from the patient was the same as the one detected in the dental unit water.


Peter Lundholm. Medicinsk riskbedömning. Folktandvården SFVH Hygiendagarna i Umeå 2014