Infection Risk Cardiac Surgery And Mycobacteria

Overview

Some people who have had heart (cardiac) surgery later develop an infection caused by a group of germs called mycobacteria — most often a type called Mycobacterium chimaera (say: my-ko-bak-TEER-ee-um ki-MAIR-uh). These germs are not the same as the one that causes tuberculosis. They live quietly in water and can sometimes grow inside the machines that keep blood cool and warm during heart surgery. These machines are called heater-cooler units. If the machine releases tiny water droplets into the air of the operating room, those droplets can land in the open chest and settle on things like replacement heart valves or grafts. The germs grow very slowly, so an infection may not show up for months or even years after the operation. This is rare, but it is serious enough that hospitals and heart surgery teams around the world now take special steps to prevent it.

No, it is uncommon. Millions of heart operations are done worldwide and only a small number have been linked to this kind of infection. Even so, because the infection can be hard to spot and slow to develop, heart surgery teams treat it as an important safety issue and follow strict prevention routines.

It affects only people who have had heart surgery, particularly open-heart surgery where a heater-cooler machine was used. The risk seems higher for people who received an implanted device during surgery, such as a replacement heart valve or a man-made blood vessel (graft). There is no evidence that it spreads from person to person, so family members and carers are not at risk of catching it from someone who has it.

Symptoms

Common symptoms

• A fever that keeps coming back, or a mild fever that never fully settles
• Night sweats and feeling chilled
• Losing weight without trying
• Unusual tiredness or low energy that does not improve
• Shortness of breath, especially with activity
• A general feeling of being unwell that lasts for weeks
• Pain, swelling, redness or discharge around the surgery scar
• Joint or muscle aches
• Signs that a heart valve is not working as well, such as a new heart murmur, ankle swelling, or breathlessness when lying flat

Symptoms in children

• Children rarely have this kind of surgery, but if they do, signs can be vague
• Poor feeding, slow weight gain, or being unusually sleepy
• Irritability or fussiness that does not settle
• Fever that keeps returning
• Faster or more laboured breathing than usual
• Any concern after heart surgery in a child should be checked by the child's heart team early

Symptoms in older adults

• Confusion or new forgetfulness can sometimes be the main sign of infection in older adults
• Falls or a general decline in strength and mobility
• Low appetite and weight loss
• Fever may be absent or lower than expected, even with a serious infection
• Breathlessness or tiredness blamed on 'just getting older' — worth mentioning to the heart team

Causes

Main causes

• The germs (mycobacteria, mostly Mycobacterium chimaera) can grow inside the water tanks of heater-cooler machines used to keep the body at the right temperature during heart surgery.
• When the machine is running, tiny droplets or mist can drift into the air of the operating room and reach the open surgical area.
• The germs can then settle on an implanted device, such as a heart valve or blood vessel graft, where they are hard for the body's immune system to clear.
• Because these germs grow very slowly, an infection can take many months to cause noticeable symptoms.
• This is not spread from person to person. It comes from the equipment and water system, not from other patients or visitors.

Risk factors

• Having had open-heart surgery where a heater-cooler machine was used
• Receiving an implanted device during surgery, such as a replacement valve or graft
• A weaker immune system, from illness or from medicines that dampen it
• Diabetes or other long-term health conditions
• Having had a long or complex operation
• The type and model of heater-cooler machine used — some designs were more prone to this problem, which is why they have been redesigned

When to see a doctor

See a doctor urgently if:

• You have a fever that keeps coming back, or a fever with shaking chills
• You have night sweats, weight loss, or feel unwell for more than two weeks
• You are more breathless than before, or your ankles are newly swollen
• Your surgery scar becomes red, warm, swollen, or starts to leak
• You feel confused, very weak, or feel that something is clearly wrong

Book a routine appointment if:

• You had heart surgery in the past and simply want to know whether you should be checked — ask your heart team or family doctor
• You are being seen for a routine follow-up and want to mention lingering tiredness, low-grade fevers, or weight loss
• You are planning other surgery or a procedure and want to share your heart surgery history
• You want to understand what your hospital is doing to prevent this infection

Diagnosis

There is no single quick test. Your doctor will start by asking about your surgery, your symptoms and when they began, and will examine you. Because these germs grow very slowly, special blood tests and lab techniques are needed, and results can take weeks. Your heart team may work with infectious disease specialists (doctors who focus on infections) and a microbiology laboratory to piece the picture together.

Tests that may be done

• Blood tests to look for signs of inflammation and infection
• Blood cultures — blood samples kept in a lab to see if germs grow; these may need to be watched for several weeks
• Specialised laboratory tests on blood or tissue to identify the exact germ, including genetic (DNA) testing
• Echocardiogram — an ultrasound scan of the heart, to check valves and any implanted device
• CT or PET scans to look for infection around the heart or in other parts of the body
• Sometimes a sample of tissue taken during a procedure, if other tests are unclear
• Review of your surgical records to see which equipment was used

What to expect at your appointment

The process can feel slow, and waiting for results is often the hardest part. Your team may ask for several blood samples taken at different times, and you may have more than one scan. If the tests are negative but your symptoms continue, your doctor may repeat them. You may also be referred to a specialist centre. Keep a simple diary of your symptoms, temperatures and how you feel — it genuinely helps your doctors.

Treatment

Treatment for this kind of infection is a long game. It usually involves a combination of germ-fighting medicines taken for many months, and sometimes an operation to remove or replace an infected device. Your team will tailor the plan to you — which part of the heart or body is affected, how strong you are, and how you respond. Because these germs are tough and grow slowly, patience and regular follow-up are a normal part of the process.

Self-care at home

• Take your medicines exactly as prescribed and finish the full course, even when you feel better
• Keep a simple record of your temperature and symptoms to share at appointments
• Attend all follow-up visits, blood tests and scans — they show whether treatment is working
• Rest when your body asks for it, and build activity back up gradually
• Eat regular, balanced meals to help keep your strength up; ask for advice if your appetite is poor
• Tell your doctor about any new symptoms or side effects rather than waiting for the next visit
• Ask your pharmacist before taking any other medicines, supplements or herbal products, as some can interact with treatment
• Keep your surgery scar clean and check it now and then for changes

Medical treatments

Doctors usually treat this infection with a combination of antibiotics — medicines that fight bacteria — taken for a long time, often many months. Treatment is usually started in hospital so you can be watched closely, and then continued at home with regular check-ups. The exact combination and duration are decided by your specialist team based on your tests, your heart function and how you respond. Some people also need extra support, such as help with breathing, nutrition, or managing other health conditions. Never start, stop or change any medicine on your own; always check with your prescriber or pharmacist.

When is surgery considered?

Sometimes medicines alone are not enough, particularly if an implanted valve or graft is infected. In that case, your surgeons may recommend another operation to remove the infected device or tissue and replace it. This is a big decision, and your heart team will discuss the benefits and risks with you and your family. Not everyone needs further surgery — it depends on where the infection is and how well you are.

Living with this condition

Living with a slow-growing infection and a long course of treatment can be tiring, and it is normal to feel frustrated by how long everything takes. Try to keep days gentle and predictable: rest when you need to, keep appointments in a diary or phone, and let people help with shopping, cooking and chores. Many people find it useful to nominate one family member or friend to come to appointments and take notes.

Lifestyle tips

• Pace yourself — short activities with rests in between work better than pushing through
• Keep a simple symptom and temperature diary to bring to appointments
• Avoid smoking, and keep away from smoky places, to protect your heart and lungs
• Limit alcohol and check with your doctor or pharmacist about whether it is safe with your treatment
• Keep up to date with routine vaccinations, but check with your team first about timing
• Wash your hands often and avoid close contact with people who have infections while you are recovering
• Build a small support network — a neighbour who can call in, a friend who can drive you to appointments

Diet and exercise

There is no special diet that treats this infection, but eating well helps your body cope with treatment. Aim for regular meals with plenty of vegetables, fruit, beans, whole grains and protein such as fish, eggs, chicken or lentils. If your appetite is low, smaller meals more often can help, and a dietitian can give practical advice. For exercise, ask your heart team what is safe for you. Many people start with short walks and gentle movement, building up slowly over weeks. Avoid heavy lifting or strenuous activity until you are told it is safe, especially after chest surgery.

Mental health and emotional wellbeing

Waiting for results, coping with a long treatment and worrying about your heart can all take a toll on your mood. Feeling anxious, low, or tearful is common and understandable — it is not a sign of weakness. Talk to your doctor or nurse if these feelings are building up, as there is real help available, including talking therapies. If you ever feel you cannot cope or have thoughts of harming yourself, please reach out for crisis support straight away — contact your local emergency number, your local crisis line, or a trusted person who can stay with you. You do not have to manage alone.

Prevention

Hospitals take this risk seriously, and a lot has changed since the problem was first recognised. Manufacturers have redesigned heater-cooler machines to reduce the chance of germs escaping. Hospitals also follow strict routines for cleaning and disinfecting the machines, testing the water, placing machines outside or well away from the operating area, and using special air filters. Many heart surgery programmes keep records of which machines were used, so that if a concern arises they can contact the right people quickly. As a patient, you cannot prevent this yourself, but you can ask your surgical team what they do to reduce the risk — good teams are happy to explain.

Vaccines

There is no vaccine that prevents this type of mycobacterial infection. The BCG vaccine protects against tuberculosis, which is a different germ, and it does not prevent this infection. Keep up to date with other recommended vaccinations, such as flu and pneumonia vaccines, because staying well overall helps your heart and your recovery — but check with your care team about timing while you are having treatment.

Screening programmes

There is no simple screening test for the general public. Some hospitals have set up follow-up programmes for people who had heart surgery using certain machines, which may include a check-up, blood tests or a scan even if you feel well. If you are not sure whether this applies to you, contact the hospital where you had your surgery and ask. If you have symptoms, testing is based on your symptoms rather than a routine screen.

Complications

If left untreated

• The infection can damage or destroy an implanted heart valve or graft, which can lead to heart failure
• It can spread beyond the heart to other parts of the body, such as the liver, spleen, bones or joints
• Ongoing inflammation can cause serious whole-body illness
• Blood vessels can weaken or, rarely, rupture near an infected graft
• Long-term infection can make further heart surgery more difficult and higher risk

Long-term outlook

This infection is serious and treatment is long, but it can be cured. Many people are treated successfully with a combination of medicines and, where needed, further surgery. Outcomes are generally better when the infection is found early, which is exactly why knowing the warning signs matters. Your heart team will follow you closely during and after treatment. If you have had heart surgery and are worried about anything, even a mild ongoing symptom, please speak to your doctor — checking early is always worthwhile.

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