dangerous family of bacteria appear to be spreading among patients of cystic fibrosis clinics in many parts of the world, a new study reveals.
The bugs, which are resistant to multiple antibiotics, seem to be spreading both within clinics and from clinic to clinic across the globe despite rigorous safeguards against infections, a team of international researchers reported Thursday in the journal Science.
“It’s a really big problem. It causes a really devastating infection, which is very hard to treat,” Dr. Andres Floto, a senior author of the paper and a doctor who treats cystic fibrosis patients at Papworth Hospital in Cambridge, England, told STAT.
The microbes, called Mycobacterium abscessus and found in water and soil, can cause devastating infections in the weakened lungs of people with cystic fibrosis. Three patients died when an outbreak occurred in a Seattle hospital’s lung transplant unit. And patients with the infection are ineligible for lung transplants at many transplant centers.
Cystic fibrosis damages the lungs of people who inherit mutated genes from their parents. Gooey mucus builds up and clogs their airways, trapping bacteria. There are about 30,000 people in the United States with cystic fibrosis and about 70,000 people worldwide.
In decades past, children born with the condition typically died before they reached school age. But medical advances have dramatically extended the life expectancy of people with the condition. In countries such as the United States, the average life expectancy for people with CF is now about 40 years.
Outbreaks of bacterial infections among CF patients over the past 15 years or so have led to substantial changes in the ways people with the condition are cared for.
Children used to be allowed to go to CF camps, where they could befriend other kids whose experiences were similar to their own.
But in the early 2000s, outbreaks of a dangerous bacterium called Burkholderia cepacia put an end to the CF camps. Being in the presence of other CF patients was ruled to be too risky, and patients are now told they should not socialize with each other.
CF clinics have strict protocols for keeping patients apart. There are no waiting rooms, for instance. Patients wear masks whenever they are in a hospital and are assigned to a room for the entirety of their visit. While other patients might go from a doctor’s office to the lab to have blood drawn, or see a nutritionist elsewhere in the hospital, all those services come to the sequestered CF patient.
The health care professionals who see CF patients in clinics wear gowns and gloves, and rooms are stringently cleaned after each patient.
Those stringent measures have been shown to stop clinic-based outbreaks of a number of bacteria that plague this population of patients. But something appears to be different with M. abscessus.
Sporadic cases have popped up in CF patients from time to time, and the accepted wisdom was that infected patients contracted the bacteria from an environmental source.
But in recent years a number of clinics have seen a surge in cases and some have experienced outbreaks. Floto approached his senior coauthor, Julian Parkhill at Britain’s Wellcome Trust Sanger Institute, for help understanding what was going on.
Parkhill’s team generated and compared genetic sequences for over 1,000 M. abscessus samples taken from 517 CF patients treated at a number of clinics in Britain, Ireland, Sweden, Denmark, the Netherlands, the United States, and Australia.
Their conclusion: While some cases are sporadic, many are so closely linked, genetically, that they are clearly transmitting from patient to patient within clinics.
The authors suggest the spread may be occurring when the bacteria — coughed out of the lungs of an infected patient — hang in the air of a treatment room or settle on a surface that an uninfected patient touches later.
How the bugs are getting around the globe, though, is not clear. Investigations have essentially ruled out patient travels or the movement of contaminated equipment, Floto and Parkhill noted.
That raises a question: Could the medical professionals caring for CF patients be inadvertently moving this bacterium around the world when they gather at medical conventions?
There is no evidence that healthy individuals are carrying and transmitting the bugs, said Dr. Ken Olivier, a CF researcher and clinician at the National Heart, Lung, and Blood Institute in Bethesda, Md. But Olivier, who was not involved in this study, said the idea needs to be explored.
“I think there are groups that are very interested in figuring out what those transmission factors are and how that may be happening,” he said.
Floto agreed there is no evidence that healthy people are spreading the outbreak strains of the bacteria around the globe. But he said it was “the most obvious possible explanation.”
Patients are worried about the new threat, said Dr. Ahmet Uluer, director of the adult CF program at the combined CF center of Boston Children’s Hospital and Brigham and Women’s Hospital, one of the largest in the country.
Uluer said his program, which manages care for about 350 adults with CF, has not had an M. abscessus outbreak. But the pathogen is on their radar.
“Definitely those reports lead to continued efforts to shore up our infection control practices,” he said.
CF patients who contract M. abscessus can experience a precipitous decline in lung function.
Getting rid of the infection is difficult, because the bacteria are resistant to a number of antibiotics. Treatment involves several drugs, which have serious side effects, said Floto. If all goes well, that treatment can last 18 months. Unfortunately, too often all does not go well; the cure rate is low.
“They’re often chronically infected for years, even with repeated antibiotic treatment,” said Parkhill of the Wellcome Trust Sanger Institute.