MDR TB Commentary

by Alan Cantwell MD and Dr. Lawrence Broxmeyer MD

In view of the continuing media stories regarding the killer TB and the 31-year old Atlanta man accused of spreading it via airplane travel, Dr Broxmeyer and I would like to add some comments/research to the controversy.
Alan Cantwell MD
Lawrence Broxmeyer MD is a New York internist who writes frequently on issues pertaining to tuberculosis. His recent paper "Diabetes mellitus, TB, and the mycobacteria", as well as other publications, are available on-line at the website. Alan Cantwell MD is a retired dermatologist who has written extensively on TB- related bacteria in cancer and AIDS. Some of his publications can be found at the website.
Drug-Resistant TB And The New
Global HysteriaSurrounding XDR TB
A review of the medical literature clearly shows that multi-drug resistant (MDR) tuberculosis (TB) and extensively drug-resistant (XDR) TB has been increasing in number for the past several decades. It is undoubtedly a more common problem than previously recognized.
It is also well accepted than TB is more frequent in the immigrant population than in the native born American population. For example, a TB study sponsored by the CDC in Los Angeles County during 1992-1994 concluded that foreign-born immigrants comprised 64% of all reported cases. Half were born in Mexico or in Central America. Screening procedures at that time also identified a large proportion of cases among recently arrived South-east Asians.
During the 1990s, multi-drug-resistant (MDR) tuberculosis, defined as resistance to at least isoniazid and rifampin, emerged as a threat to TB control, both in the United States and worldwide.
A CDC report in 2006 concluded that 4% of the multi-drug resistant (MDR) TB isolates in the US were extensively drug resistant (XDR). In Latvia, Europe, XDR isolates comprised 19% of the MDR isolates; and in South Korea XDR strains were 15% of the isolates.
The "extreme type" of XDR TB is certainly not rare. Many people carry TB bacteria; and TB bacteria mutate - and with bacterial mutations comes inevitable drug resistance.
Why is the CDC and the media making such a big deal about one case XDR TB discovered in a healthy-looking young white male lawyer from Atlanta when MDR and XTB cases are widespread worldwide?
Why pick on this poor guy when a spot of his lung was detected by X-rays 5 months earlier, and he was placed on anti-TB antibiotics for more than two weeks before he took his now infamous plane trip to Europe.
Until this Atlanta lawyer was made the media Poster Boy for TB, few people thought about or cared about an epidemic of TB. When the current media obsession with "killer" TB subsides, one can only hope that some sanity is restored to the realities of modern TB.
Lawrence Broxmeyer MD  
Alan Cantwell MD  
References and Summaries:
N Engl J Med. 1996 Apr 11;334(15):933-8. Links
Comment in:
N Engl J Med. 1996 Apr 11;334(15):981-2.
N Engl J Med. 1996 Aug 29;335(9):675; author reply 675-6.
Transmission of multidrug-resistant Mycobacterium tuberculosis during a long airplane flight.
Kenyon TA,
Valway SE,
Ihle WW,
Onorato IM,
Castro KG.
Epidemiology Program Office, National Center for HIV, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
BACKGROUND. In April 1994, a passenger with infectious multi-drug resistant tuberculosis traveled on commercial-airline flights from Honolulu to Chicago and from Chicago to Baltimore and returned one month later. We sought to determine whether she had infected any of her contacts on this extensive trip. METHODS. Passengers and crew were identified from airline records and were notified of their exposure, asked to complete a questionnaire, and screened by tuberculin skin tests. RESULTS. Of the 925 people on the airplanes, 802 (86.7 percent) responded. All 11 contacts with positive tuberculin skin tests who were on the April flights and 2 of 3 contacts with positive tests who were on the Baltimore-to-Chicago flight in May had other risk factors for tuberculosis. More contacts on the final, 8.75-hour flight from Chicago to Honolulu had positive skin tests than those on the other three flights (6 percent, as compared with 2.3, 3.8, and 2.8 percent). Of 15 contacts with positive tests on the May flight from Chicago to Honolulu, 6 (4 with skin-test conversion) had no other risk factors; all 6 had sat in the same section of the plane as the index patient (P=0.001). Passengers seated within two rows of the index patient were more likely to have positive tuberculin skin tests than those in the rest of the section (4 of 13, or 30.8 percent, vs. 2 of 55, or 3.6 percent; rate ratio, 8.5; 95 percent confidence interval, 1.7 to 41.3; P=0.01). CONCLUSIONS. The transmission of Mycobacterium tuberculosis that we describe aboard a commercial aircraft involved a highly infectious passenger, a long flight, and close proximity of contacts to the index patient.
PMID: 8596593 [PubMed - indexed for MEDLINE]
Tuber Lung Dis. 1996 Dec;77(6):524-30. Links
Tuberculosis among foreign-born persons in Los Angeles County, 1992-1994.
Zuber PL,
Knowles LS,
Binkin NJ,
Tipple MA,
Davidson PT.
Division of Tuberculosis Elimination, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
OBJECTIVES: To describe the epidemiology of foreign-born tuberculosis (TB) cases in Los Angeles County and to evaluate current TB screening and follow-up of immigrants and refugees (I&R) to the USA. DESIGN: Retrospective analysis of the Los Angeles County TB registry between October 1992 and December 1994. We matched all cases who entered the USA during fiscal year 1993 (FY93) with a database from the tracking system of I&R with suspected TB. RESULTS: Foreign-born persons accounted for 64% of all reported TB cases. Half were born in Mexico or Central America. Standardized incidence rates were 3-5 times higher than those of US- born persons for Mexicans and Central Americans, 6-7 times higher for North-east Asians, and 10-15 times higher for South-east Asians. Among foreign-born cases who arrived during FY93, 5% of the Mexicans and Central Americans, 48% of the North-east Asians and 67% of the South-east Asians were registered by the tracking system. CONCLUSION: Mexicans and Central Americans accounted for the majority of cases but had a lower incidence of TB than Asians. The current screening procedures identify a large proportion of cases among recently arrived South-east Asians, but contribute little to the control of TB among Mexicans and Central Americans.
PMID: 9039445 [PubMed - indexed for MEDLINE]
MMWR Morb Mortal Wkly Rep. 2006 Mar 24;55(11):301-5.? Links
Emergence of Mycobacterium tuberculosis with extensive resistance to second-line drugs--worldwide, 2000-2004.
Centers for Disease Control and Prevention (CDC).
During the 1990s, multidrug-resistant (MDR) tuberculosis (TB), defined as resistance to at least isoniazid and rifampin, emerged as a threat to TB control, both in the United States and worldwide. MDR TB treatment requires the use of second-line drugs (SLDs) that are less effective, more toxic, and costlier than first-line isoniazid- and rifampin-based regimens. In 2000, the Stop TB Partnership's Green Light Committee was created to increase access to SLDs worldwide while ensuring their proper use to prevent increased drug resistance. While assisting MDR TB treatment programs worldwide, the committee encountered reports of multiple cases of TB with resistance to virtually all SLDs. To assess the frequency and distribution of extensively drug-resistant (XDR) TB cases, CDC and the World Health Organization (WHO) surveyed an international network of TB laboratories. This report summarizes the results of that survey, which determined that, during 2000-2004, of 17,690 TB isolates, 20% were MDR and 2% were XDR. In addition, population-based data on drug susceptibility of TB isolates were obtained from the United States (for 1993-2004), Latvia (for 2000-2002), and South Korea (for 2004), where 4%, 19%, and 15% of MDR TB cases, respectively, were XDR. XDR TB has emerged worldwide as a threat to public health and TB control, raising concerns of a future epidemic of virtually untreatable TB. New anti- TB drug regimens, better diagnostic tests, and international standards for SLD-susceptibility testing are needed for effective detection and treatment of drug-resistant TB.
PMID: 16557213 [PubMed - indexed for MEDLINE]