UW medical center has identified and treated four patients.

A fourth patient was recently contaminated with bacteria that can cause Legionella. The investigation team found contaminated equipments in the cardiac units operating room, which may be the root cause of the outbreak.

Following four infections and two deaths at the hospital’s Cascade Tower, the UW Medical Center (UWMC) has been straining to recover from and prevent further infections by the Legionella bacterium.

The bacteria, which causes Legionnaires’ disease (a form of pneumonia), has so far been found in a sink, an ice machine, and three of the hospital’s heater-cooler machines, a device used to manage the temperature of a patient’s blood during an organ transplant.

Though the water from the heater-cooler machines does not come in contact with the blood of a patient, they have been previously linked to infections and deaths at other sites.

Legionella bacteria are found naturally in the soil, air, and bodies of water like lakes and streams. However, they are also capable of thriving in artificial environments, such as air-conditioning systems, indoor plumbing, and water tanks.

UWMC has had problems with Legionella in these environments in the past. The Washington State Department of Labor & Industries previously investigated worker safety after the bacteria was detected in a cooling tower that helped moderate the hospital’s temperature.

The Legionella bacteria detected in the cooling tower had a different genomic makeup than the strain recently found in patients, suggesting they are unrelated, according to Tina Mankowski, director of UW Medicine Media Relations.

Though a source of the bacteria has yet to be identified, the hospital has taken measures to either prevent its further spread or clear the system entirely.

Infected equipment has been taken out of service and cleaned with the heater-cooler machines awaiting inspection from their manufacture before being brought back online.

Additionally, the use of water in Cascade Tower was severely restricted, with bottled water being used for drinking instead. On Tuesday night, the hospital completed a hyper-chlorination of the water system, a process in which a chlorine solution was added to the system until it reached toxic levels sufficient to kill the Legionella bacteria. The water was then cleared until the chlorine returned to safe drinking levels.

To prevent further exposure, filters that remove Legionella bacteria have been or are being installed on the showers and sinks in the inpatient section of Cascade Tower.

Though the bacteria, which can cause a lethal form of pneumonia to develop, is a grave threat to the already ill, it should not be a personal health concern to students, Mankowski said.

She went on to say workers in the hospital are also not in danger due to UW Medicine’s precautions.

The hospital is served by five separate water feeds which do not mix, preventing the spread of Legionella, she said. Other buildings at the UWMC have tested negative for the bacteria.

The UW campus itself is on an unconnected, separate system.

Transmission almost never occurs person-to-person. The primary cause of Legionnaires’ disease is the inhalation of the aerosolized water droplets (such as in a shower) infected with the bacteria.

When Legionnaires’ disease does develop, it can be treated with antibiotics. Of an estimated 25,000 cases in the United States each year, 15 percent of cases are fatal, according to OSHA. 

“People who are very ill, such as those in hospitals, are more susceptible because of their [weakened immune systems],” Mankowski said.

The most vulnerable populations are people over the age of 50, current or former smokers, people with chronic lung diseases, people with weak immune systems (such as cancer or diabetes patients), and people who take drugs that suppress the immune system (after a transplant operation or chemotherapy), according to UWMC.

Mankowski also said that many healthy people may be infected without adverse health effects such as pneumonia because of their effective immune systems.


Reach reporter Brendan Gerrity at news@dailyuw.comTwitter: @brerrity

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