Jul 5, 2007 (CIDRAP News) Experts have concluded that the Atlanta man whose case of drug-resistant tuberculosis triggered an international health scare in May has a less dangerous form of the disease than was previously believed.
The patient, Andrew Speaker, has multidrug-resistant tuberculosis (MDR TB), not extensively drug-resistant TB (XDR TB), experts from the Centers for Disease Control and Prevention (CDC) and National Jewish Medical and Research Center (NJMRC) reported at a press conference on Jul 3.
The finding means it will be easier to treat him because more drugs are likely to work, but the CDC would have issued an international alert even if it had known the true diagnosis when Speaker was traveling in Europe, potentially exposing other airline passengers to the deadly disease, officials said.
Against public health officials' advice, Speaker, 31, flew from Atlanta to Paris for his wedding and honeymoon on May 12, when he was believed to have MDR TB. After learning on May 18 of his trip, the CDC tried to locate him and warn him not to travel on commercial flights because of the risk of exposing others, according to an agency timetable of the events. On May 22 a CDC test indicated he had XDR TB.
But Speaker and his wife changed their itinerary to elude health authorities and, after several flights in Europe, flew from Prague to Montreal. They then rented a car and re-entered the United States. The CDC finally located him on May 25 and ordered him into isolation, the first such action by the agency since 1963.
A few days later, on May 29, the CDC publicly announced the incident in an effort to alert people who had flown on the same transatlantic flights as Speaker so they could be tested for TB. Soon afterward, Speaker was flown to National Jewish Medical and Research Center in Denver, which specializes in treating respiratory diseases.
The change in Speaker's diagnosis was good news for him and his fellow airline passengers. But the lengthy Jul 3 news conference pointed up the lack of a foolproof test for distinguishing between MDR and XDR TB and put the CDC on the defensive concerning its testing procedures and response to the situation.
Dr. Charles Daley of NJMRC said the earlier XDR diagnosis indicated that only two drugs would be likely to help Speaker, but the change to MDR means several more may work. "We went from at the end of May basically two drugs to now all but three or four," he said.
Previously, Speaker's doctors were considering removing part of one of his lungs to cure him. Now, said Daley, "We've put surgery on hold for the time being while we build a strong treatment regimen with drugs that we didn't have available before."
He added, "Many people out there who may have been exposed have been hearing that no drugs are available. . . . Now we know that there is something we can do for them."
Speaker, in a statement read at the news conference by NJMRC spokesman William Allstetter, described himself as "incredibly relieved" by the change in diagnosis. "The truth is that my condition is the same as it was in early May, back before there was a huge health scare," he said. He has been described as not yet having any symptoms of the slow-growing infection, which was discovered as a result of an injury-related x-ray last January.
In his statement, Speaker acknowledged that health authorities must take difficult steps to protect the public at times, but added, "With great power comes great responsibility. In the future I hope they realize the terrible chilling effect they can have when they come after someone and their family on a personal level. They can, in a few days, destroy an entire family's reputation, ability to make a living, and good name."
He also expressed hope that the change in his diagnosis will calm the fears of those who flew with him and that the whole episode will focus more attention on TB, which he said accounts for a quarter of the world's preventable deaths.
Much of the news conference focused on testing issues. The CDC concluded Speaker had XDR TB after testing a bronchoscopy sample that had been taken in March at an Atlanta hospital, said Dr. Mitchell Cohen, director of the CDC's Coordinating Center for Infectious Diseases. The test involved the "agar proportion method," which is approved by the Clinical Laboratory Standards Institute, he said.
"The original sample is no longer available for retesting. All subsequent samples from induced sputums have shown MDR [TB]," Cohen added.
Daley said NJMRC used three types of tests, including the agar proportion method, on at least three samples from Speaker. "Out of all the cultures doing it three different ways, the results were consistent," he said. "We were very sure of our results that this is MDR, not XDR."
"This was repeated at the CDC and they confirmed our findings of multidrug resistant disease," Daley said. However, he said NJMRC is still waiting for test results on a sample taken from the bronchoscopy specimen in March.
"This discrepancy or discordance of results happens all the time in drug susceptibility testing, including reference labs," he added. "It's not a new thing. It's a frustration that we have to deal with. I don't know why the first result at the CDC showed XDR TB and ours did not. There are a number of ways this can happen."
In response to a question, Cohen at one point said the test that led to the XDR TB diagnosis actually revealed a mix of MDR and XDR strains, with XDR the smaller proportion. He added that the test does not yield a "yes or no answer" and is very complicated, in part because of how slowly TB organisms grow.
Daley later disagreed about the test showing both MDR and XDR strains. "They did not find XDR and MDR really in the specimen," he said. "It's a very technical and complicated test and in trying to simplify it, I'm not sure that happened."
Cohen stressed that although MDR TB is less dangerous than XDR, it is still difficult to treat, requiring 2 years of "relatively toxic" drug treatment. "It's very different from drug-susceptible TB," he said.
The cure rate for fully susceptible TB is 95% to 97%, versus about 70% for MDR TB, Cohen reported. "With XDR, the chances of being cured are probably 30 to 40%," he said.
The CDC still wants those who were on transatlantic flights with Speaker to get follow-up TB tests, Cohen said. The agency previously recommended that those passengers undergo initial skin or blood tests and then be retested 8 to 10 weeks later, since an initial positive test could reflect an earlier exposure to TB.
Speaker has had several negative sputum smear tests for TB, suggesting that his chance of spreading the disease to others is fairly low, according to the NJMRC. He is still under an isolation order from Denver public health authorities, officials at the news conference said.
Cohen noted that MDR TB is resistant to the most commonly used drugs (isoniazid and rifampin) and can be spread to others. "Therefore the public health actions that CDC took in this case . . . are sound and appropriate," he said, adding that the World Health Organization's recommendations regarding TB and airline travel are the same for MDR and XDR forms.
In response to questions, both Cohen and Daley repeatedly affirmed that the public health response is the same for MDR and XDR TB. "From a clinical perspective this [difference] is important, but from a public health perspective, no, there's no difference between MDR and XDR," said Daley.
Cohen said the CDC became formally involved in the situation on May 18, when Georgia public health officials told the agency that a patient with MDR TB had traveled out of the country. The CDC began trying to locate Speaker at that point, though XDR TB wasn't diagnosed until May 22, according to the CDC timetable of the episode.
CDC transcript of Jul 3 teleconference
May 29 CIDRAP News story "Airline trips by resistant-TB patient trigger alert"
CDC's XDR TB page