Ask the Doctors

Dear Doctors: I suffered extensive fatigue that I had attributed to a COVID-19 infection. Then a lung culture found something called mycobacterium avium complex. Would you kindly consider discussing this? I realize it’s not a common illness, but for that reason it can go undetected and undiagnosed.

Dear Reader: Mycobacterium avium complex refers to a group of bacteria that are naturally present in the soil, water and dust all around us. Also known as MAC, these microbes are harmless to the majority of people. But when someone is living with a chronic lung disease or a weakened immune system, inhaling the bacteria can lead to an infection. When this occurs, it is known as MAC lung disease. Unlike tuberculosis, which is also a bacterial lung infection, MAC lung disease is not contagious.

MAC lung disease can affect the lungs in two different ways. One, known as nodular bronchiectatic, causes tiny knots to develop within the smaller airways and air sacs of the lungs. Over time, the resulting inflammation leads to scarring in the tissues of the lungs. This makes it difficult to naturally clear mucus, which, in turn, increases the risk of developing a respiratory infection. The other, more aggressive form of MAC is known as fibrocavitary disease. This is when damage to the lung tissue leads to the development of pits, or even holes, in the lung tissue.

Symptoms of both forms of MAC lung disease include the pervasive fatigue that you experienced. This is due to the extra work your body is doing to try to fight off the infection, and to the damage to the lung tissue itself. Additional symptoms can include a chronic cough that can be dry or may produce mucus; shortness of breath; a sensation of heaviness or pain in the chest or lungs; a low-grade fever that is not associated with another illness; unintentional weight loss; a decrease in appetite; and night sweats. If coughing brings up mucus or sputum, it is possible that it may be tinged with blood.

Diagnosis begins with a physical exam, a medical history and a detailed description of symptoms. When MAC lung disease is suspected, sputum cultures can identify the presence of bacteria. These bacteria are common, so repeated cultures may be required to confirm a persistent infection. Scans, such as a CT or an X-ray, can reveal physical changes to the lungs. A bronchoscopy, which uses a flexible scope to examine the lungs, can confirm a diagnosis.

Treatment depends on each person’s specific symptoms, current physical health and medical history. When symptoms are mild, the condition may be closely monitored but not actively treated. This is known as watchful waiting. Some people are prescribed therapies to help clear mucus -- and bacteria -- from the lungs. When needed, antibiotics are prescribed. This therapy often lasts for a year or more. And due to the challenges of antibiotic resistance, it typically requires the use of multiple antibiotics.

To ease symptoms, your doctor has likely urged to you to eat a healthful diet, avoid tobacco, do breathing exercises and get vaccinated for flu and COVID-19. We hope you follow through.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Hello, dear readers, and welcome to the monthly letters column. We are well into the third month of the new year, and for some of us -- the data say it’s probably most of us -- the resolutions we made on Jan. 1 have already fallen by the wayside. We have been hearing from readers asking for encouragement, and have also had readers sharing tips that are helping them stay on course. We’ll have a resolution reset column coming soon. And now, onward to the mail.

-- A column about how research shows the gut microbiome gradually recovers after the use of antibiotics has caused a reader a bit of confusion. “This column says that probiotics can delay recovery after antibiotics, but it also says taking fermented foods with live cultures is helpful,” he wrote. “Are these live cultures not considered probiotics? Please clarify what is meant by ‘probiotics.’”

When you take antibiotics, both the pathogen that made you sick and the beneficial bacteria living in the gut are killed off. After treatment, it takes a month or two for the microbial colonies of the gut microbiome to be restored. Probiotic supplements, which you can buy at drug and grocery stores, and fermented foods both contain probiotics. However, supplements contain high amounts of a limited variety of microbes, and because the gut is basically a clean slate after antibiotic treatment, taking a supplement can lead to an off-balance colonization of the gut. Researchers have found that this actually slows down the natural recolonization of the gut. Fermented foods also contain probiotics, but in a wider variety and smaller numbers. Eating them creates a gentler and more natural path to recolonizing the gut with your unique microbial profile.

-- We get a lot of letters about toenail fungus, a common infection that is notoriously difficult to cure. We recently heard from a reader who has been struggling with it for several months. “Last fall, I started getting a yellow and crumbling nail on the big toe of my right foot. I used Vicks VapoRub every day and soaked with tea tree oil, and it went away,” he wrote. “About a month after I stopped treating it, the yellow color started coming back. Why did that happen?”

Unfortunately, the scenario described is quite common. It is possible to manage a toenail fungus infection with topical treatments so that the appearance of the nail improves or even returns to normal. However, the chances the infection has been eradicated are small. Topical treatments can’t adequately penetrate the tough nail to completely kill off the fungus. Oral anti-fungal medications, while more effective, are not always completely successful. If you do wish to try that route, your doctor can prescribe the medication, explain the possible side effects and guide you through the treatment.

We are hearing from a lot of new readers, so it’s time for a reminder that we can’t look at medical records, comment on medications or treatments or offer a second opinion. And, as always, thank you for your letters. We love hearing from you.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: We live in the fire zone in Altadena, California. After the evacuations ended, we came home, and now my throat is constantly sore. There’s no smoke smell, but my husband says the air can still be unhealthy. Why would that be? The air quality numbers are good, so it’s confusing.

Dear Reader: We are near one of the fire zones in Southern California and are sadly familiar with the ongoing aftermath. Over the course of 24 days, fire tore through 60 square miles, destroyed more than 16,000 homes and businesses and damaged thousands more. At least 29 people died, and many more, including rescue workers, were injured. Now the flames are out, but the health dangers continue. This is due to fine particulates released by the fires. We touched on this in a column last month, but your question allows a more detailed look at the issue.

Particulates are the microscopic bits of burned materials that become suspended in wildfire smoke. Their extremely small size means they can be inhaled into the deepest recesses of the lungs. These are the alveoli, which are minute air sacs clustered at the ends of the bronchial tubes. The delicate membranes of these air sacs are where the oxygen we breathe in enters the bloodstream and the carbon dioxide produced by metabolic processes exits. To get a sense of just how small alveoli are, an adult has about 240 million in each lung.

The particulates released in urban fires differ from those generated by forest fires. In urban fires, particulates come from the vast array of manmade materials found in the built environment. They include building materials, appliances, electronics, plastics, vehicles, batteries, gasoline, propane, paints, stains and solvents, cleaning products, pesticides, carpets, wood and tile floors and furnishings. As these burn, dangerous substances are released into the air. They include heavy metals such as lead, zinc and chromium; toxic chemicals such as formaldehyde, benzene, ethylene glycol-toluene, chlorine and asbestos from older homes; and an array of carcinogens known as polycyclic aromatic hydrocarbons, or PAHs.

The AQI, or air quality index, warns about common pollutants such as ozone, carbon monoxide, sulfur dioxide and nitrogen dioxide. However, many of the particulates generated in urban fires are outside of its scope. That’s the disconnect -- and the ongoing health risks -- that your husband is referencing. Wildfire particulates mix with the ash and soot that fall to the ground. When blown by wind or disturbed during debris removal, they can once again become airborne. Updated air quality specific to wildfire particulates is available at fire.airnow.gov.

People returning to burn areas are advised to take precautions for several months. Keep windows and doors closed whenever there’s a smoky smell. Use an appropriately sized air purifier that has a HEPA filter, and change the filter often. When it’s windy, and when debris removal occurs, use an N95 mask while outdoors.

Wildfire particulates are known to ramp up inflammation throughout the respiratory tract. If the throat irritation you are experiencing doesn’t clear up, please check in with your health care provider.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)