Mycobacterium Chimaera Infection: Information on Causes, Diagnosis & Treatments
Invasive mycobacterium chimaera infections are occurring at an alarming rate after individuals undergo open-heart surgery. The infection is caused by aerosols that are produced by contaminated heater-cooler units required during most open-heart surgical procedures. These infections are occurring despite intensive cleaning and disinfection procedures between surgeries.
The number of cases of Mycobacterium chimaera problems has been rising significantly in the healthcare industry. The disastrous infections now associated with heart valve replacement and vascular grafts following open-heart surgery using heater-cooler devices were once thought to be associated with surgical site infections involving non-tuberculosis mycobacteria. Research now shows that the bacteria invades the body during the surgical procedure and not afterward at the surgical incision site.
Heater-cooler devices are necessary during open-heart surgery to cool or warm the patient during the procedure. Unfortunately, mycobacterium chimaera can thrive in the water tank(s) that regulates the blood's temperature. It is essential to understand that the water in the tank never comes into direct contact with the patient's body fluids or blood. However, components in the unit can aerosolize the water, and if contaminated with Mycobacterium chimaera, can release water vapors containing the bacteria over and into the patient's open chest cavity.
- Who Is at Risk for Mycobacterium Chimaera Infections?
- FDA Safety Communication
- Mycobacterium Chimaera Infection Symptoms
- Diagnosing and Treating the Infection
Who Is at Risk for Mycobacterium Chimaera Infection?
Individuals most at risk for developing mycobacterium chimaera infections include those who have undergone aortic vascular grafts surgery or open-heart valve replacement surgery. However, even if the infection is acquired, it may not produce any symptoms or damage to the body. Typically, those most susceptible to a Mycobacterium chimaera infection caused by a heater-cooler unit tend to be very ill patients who have an underlying lung condition, a compromised immune system, are diabetic, or undergoing cancer treatment (chemotherapy).
The CDC (Centers for Disease Control and Prevention) has issued a warning to patients and healthcare providers of the potentially serious risks associated with open cavity surgeries that use heater cooler units. This affects more than 250,000 individuals who undergo these procedures in America every year.
The federal agency also released a Health Alert Network Advisory to assist healthcare providers identify and inform patients who might be at risk. The most common surgeries that use a heater-cooler device include:
- Cardiac and cardiothoracic surgeries
- Open-heart surgery
- Heart bypass surgery
- Aorta Procedure
- Ventricular implant
- Heart transplant
- Cardiopulmonary surgery
- Pulmonary artery surgery
- Liver transplants
- Partial hepatectomy
- Liver resection (tumor removal)
- Lung transplants
- Lung resection surgery
Since healthcare providers were first warned of the potential risks of patients acquiring Mycobacterium chimaera infections after undergoing open-heart surgical procedures, extra measures have been initiated. These efforts reduce the possibility of developing dangerous infections during open cavity surgical procedures. However, there is a small potential risk of the infection occurring.
FDA Safety Communication
In June 2016, the Food and Drug Administration (FDA) issued a Safety Communication announcement concerning Mycobacterium chimaera infections associated with heater cooler units used during the procedure. The communication warned healthcare providers of contamination issues in the water supply and on the production line involving heater-cooler units. This follows changes made by the manufacturer in August 2014 when they updated their cleaning and disinfecting procedures to eliminate contamination of their devices that were causing the Mycobacterium chimaera infection problem.
The Safety Communication revealed how reports have been received at the federal agency involving patients in the United States who were infected with Mycobacterium chimaera after they had undergone open-heart surgery involving the use of heater-cooler devices. The FDA notes that these devices were all manufactured before September 2014. The FDA warned healthcare providers to take immediate action including:
- "Immediately remove from service any heater cooler device, etc., tubing, connectors that tested positive for Mycobacterium chimaera or been associated with known Mycobacterium chimaera patient infections at your facility."
- "Direct and channel the heater cooler exhaust away from the patient, e.g., to the operating room exhaust vent."
- "Use of these devices should be limited to emergent and/or life-threatening situations of no other heater cooler devices are available."
When the true cause of Mycobacterium chimaera infections was first identified and verified, many hospitals responded to the recommendations made by the FDA involving the use of heater cooler units to reduce the potential risk of harming their patients. Some of these recommendations included:
- "Strictly adhere to the cleaning and disinfection instructions provided in the manufacturer's device labeling. Ensure you have the most current version of the manufacturer's instructions for use readily available to promote adherence."
- "Established regular cleaning, disinfection, and maintenance schedules for heater cooler devices according to the manufacturers' instruction to minimize the risk of bacterial growth and subsequent infection."
- "Consider performing environmental, air, and water sampling and monitoring if heater cooler contamination is suspected. Environmental monitoring requires specialized and expertise and equipment to collect and process samples, which may not be feasible for all facilities."
- "Do not use tap water to rinse, fill, refill, or top off water tanks since this may introduce non-tuberculosis Mycobacterium chimaera organisms. Use only sterile water or water that has been passed through a filter of less than or equal to 0.22 microns."
- The FDA also provided recommendations for patients to remain aware that in the United States "most cardiopulmonary bypass procedures involve the use of a heater-cooler device… [which] are important to patient care and, in appropriately selected patients, the benefits of temperature control necessary during open chest cardiothoracic procedures generally outweigh the risk of infection transmission associated with using these devices."
- The federal agency also noted that " there may be an increased risk of infections if you received a heart valve, graft, left ventricle assist device (LVAD), or any other prosthetic product/material or had a heart transplant."
Mycobacterium Chimaera Infection Symptoms
Individuals who do not feel well after undergoing open-heart surgery might consider visiting their doctor to be tested for a Mycobacterium chimaera infection. The most common symptoms associated with the disease include:
- Fever symptoms with the temperature of 100.4°F (38°C) that produce shivers and the sensation of heat
- Muscle or joint pain
- Night sweats
- Increasing shortness of breath
- Coughing up blood
- Persistent coughing
- Unexplained weight loss
- Loss of appetite
- Vomiting or feeling sick
- Unusual tiredness
- Warmth, redness, pain, or pus at the surgical site
Patients who have previously undergone open-heart surgery who experience any of the symptoms listed above should contact their health care provider for a physical examination and blood test.
Diagnosing and Treating Mycobacterium Chimaera Infection
Mycobacterium chimaera infections can be easily diagnosed using an extensive blood sample tests. While the results are not immediate, the infection can be confirmed after the sample is cultured in a growing environment for several weeks. Without treatment, mycobacterium chimaera infections can cause serious illnesses and potentially cause death. The bacteria infection is not normally spread by person-to-person contact.
Common treatments for Mycobacterium chimaera infections include strong antibiotic medications that may need to be taken for the remainder of the patient's life to ensure the infection does not recur and cause damage to the heart, liver, lung or another organ. In some cases, surgical treatments have been required to minimize the potential risks of the patient. In these cases, delaying surgery is not recommended.