A bacteriological survey of tuberculosis due to the human tubercle bacillus (Mycobacterium tuberculosis) in south-east England: 1984-91

Mycobacterium tuberculosis pathogenesis and molecular determinants of virulence

Tuberculosis (TB), one of the oldest known human diseases. is still is one of the major causes of mortality, since two million people die each year from this malady. TB has many manifestations, affecting bone, the central nervous system, and many other organ systems, but it is primarily a pulmonary disease that is initiated by the deposition of Mycobacterium tuberculosis, contained in aerosol droplets, onto lung alveolar surfaces. From this point, the progression of the disease can have several outcomes, determined largely by the response of the host immune system. The efficacy of this response is affected by intrinsic factors such as the genetics of the immune system as well as extrinsic factors, e.g., insults to the immune system and the nutritional and physiological state of the host. In addition, the pathogen may play a role in disease progression since some M. tuberculosis strains are reportedly more virulent than others, as defined by increased transmissibility as well as being associated with higher morbidity and mortality in infected individuals. Despite the widespread use of an attenuated live vaccine and several antibiotics, there is more TB than ever before, requiring new vaccines and drugs and more specific and rapid diagnostics. Researchers are utilizing information obtained from the complete sequence of the M. tuberculosis genome and from new genetic and physiological methods to identify targets in M. tuberculosis that will aid in the development of these sorely needed antitubercular agents.

High proportion of multi-drug resistant Mycobacterium tuberculosis in Saudi Arabia

289 patients with TB, presented to a single tertiary care unit in Saudi Arabia between 1989 and 1994. The isolate from each patient was tested for in vitro susceptibility to rifampicin, isoniazid, ethambutol, pyrazinamide and streptomycin. 25 patients (8.7%) had isolates resistant to at least 1 anti-tuberculous drug. Single drug resistance (SDR)-mainly isoniazid-occurred in 14, and resistance to at least 2 drugs (multi-drug resistance-MDR) in 11, of which 8 were due to both isoniazid and rifampicin. Previous drug treatment occurred significantly more often in patients with MDR (8/11), than SDR (1/14) (p = 0.0021). A literature review of another 5571 patients from Saudi Arabia with TB revealed an incidence of resistance of M. tuberculosis isolates to at least 1 anti-tuberculous drug tested, of between 5.9% and 44%. The overall percentage of patients with resistant tuberculosis (including our own patients) was 14.9%. Resistance to streptomycin (8.9%), isoniazid (6.6%), and rifampicin (6.1%) were the commonest reported. There were as many patients with MDR as there were SDR. A history of previous anti-tuberculous treatment was found in over 40%. The high rate of anti-tuberculous resistance in Saudi Arabia may be due to poor supervision of anti-TB treatment, the embryonic healthcare system, over-the-counter antibiotic availability, treatment of endemic diseases such as brucella with rifampicin etc., a large migrant work force, and possibly increased toxicity of anti-tuberculous drugs secondary to the high incidence of chronic liver disease in the country.

Tuberculosis in inner London: evidence for an increase in young adults and immigrants

We report a marked increase in the rate of notifications of tuberculosis in young adults in the London Borough of Lambeth. Analysis of notifications made to the Proper Officer over a 10-year period showed that the age specific notification rate in the cohort aged 20-44 years increased from 30/100,000 in 1983 to 51/100,000 in 1992. Analysis of St. Thomas' Hospital laboratory records of patients seen between 1984 and 1991 from whom Mycobacterium tuberculosis was isolated showed an increase in the number of patients of African origin from five in the first half of the study period (1984-7) to 25 in the second half (1988-91): 21 of these 25 had immigrated into England within 4 years of their illness. This finding is being further investigated in a prospective study of ethnicity, travel history and date of immigration of Lambeth residents notified with tuberculosis.

Tuberculosis in London: a review, and an account of the work of the London Consultants in Communicable Disease Control Group Working Party

Tuberculosis (TB) has been recorded in London for centuries but reports have declined over the last 100 years, with a 10-fold decrease between 1948 and 1987. However, from 1987-1993 notifications of TB in London rose by 34%, compared with 15% nationally. This rise, together with concerns about undernotification and the emergence of multi-drug resistance in New York, led to establishment of a London Consultants in Communicable Disease Control Working Party on TB to review current surveillance data. Notifications to the Office of Population Censuses and Surveys from the London Boroughs declined by approximately 6.5% per year from 1982-1987. If this had continued until 1993 there would have been 3579 fewer notifications than actually received. The proportion of cases in the 15-44 age group rose markedly in males. The proportion of notifications in those aged 65 and above was higher in the Thames Regions outside London, where the total TB notifications declined by 3.5% over the same period. Recommendations were made to improve TB surveillance in London; and a city-wide surveillance function was established in 1994 to collate and monitor data on TB.

Isolation of mycobacteria from patients seropositive for the human immunodeficiency virus (HIV) in south east England: 1984-92

BACKGROUND

Tuberculosis and other mycobacterial infections are well recognised complications of HIV infection and surveillance is thus required.

METHODS

All mycobacteria isolated from HIV positive subjects and referred to the Public Health Laboratory Service South East Regional Tuberculosis Centre (SERTC) from the first such case in 1984 until the end of 1992 were reviewed.

RESULTS

A total of 803 mycobacteria isolated from 727 HIV positive subjects were referred to the SERTC during the study period. A single species was isolated from 660 patients: 150 members of the tuberculosis complex (146 M tuberculosis, two M bovis, and two M africanum), 356 M avium-intracellulare (MAI), and 154 other environmental mycobacteria. More than one mycobacterium was isolated from 67 patients. In 12 cases M tuberculosis and MAI were isolated from the same patient, almost always in that sequence, with an interval of 8-41 months between isolations. Most of the 407 isolates of MAI (74%) were considered to be clinically significant and often caused disseminated disease. In other cases single isolates of MAI were obtained from sputum or faeces and occasionally such isolates preceded disseminated disease by several months. Only 33 (14%) of the 229 isolates of environmental mycobacteria other than MAI were considered clinically significant.

CONCLUSIONS

HIV related mycobacterial disease is increasing in incidence in south east England. Further studies are required to determine the significance of single isolates of MAI and other environmental mycobacteria as a guide to the need for preventive chemotherapy or immunotherapy.