The present update on the global distribution of Mycobacterium tuberculosis complex spoligotypes provides both the octal and binary descriptions of the spoligotypes for M. tuberculosis complex, including Mycobacterium bovis, from >90 countries (13,008 patterns grouped into 813 shared types containing 11,708 isolates and 1,300 orphan patterns). A number of potential indices were developed to summarize the information on the biogeographical specificity of a given shared type, as well as its geographical spreading (matching code and spreading index, respectively). To facilitate the analysis of hundreds of spoligotypes each made up of a binary succession of 43 bits of information, a number of major and minor visual rules were also defined. A total of six major rules (A to F) with the precise description of the extra missing spacers (minor rules) were used to define 36 major clades (or families) of M. tuberculosis. Some major clades identified were the East African-Indian (EAI) clade, the Beijing clade, the Haarlem clade, the Latin American and Mediterranean (LAM) clade, the Central Asian (CAS) clade, a European clade of IS6110 low banders (X; highly prevalent in the United States and United

We present a short summary of recent observations on the global distribution of the major clades of the Mycobacterium tuberculosis complex, the causative agent of tuberculosis. This global distribution was defined by data-mining of an international spoligotyping database, SpolDB3. This database contains 11,708 patterns from as many clinical isolates originating from more than 90 countries. The 11,708 spoligotypes were clustered into 813 shared types. A total of 1,300 orphan patterns (clinical isolates showing a unique spoligotype) were also detected.

A recent European Union Directive required member states to put monitoring and control programmes in place, of which vaccination is a central component. Live Salmonella vaccines generally confer better protection than killed vaccines, because the former stimulate both cell-mediated and humoral immunity. Administering Salmonella bacteria orally to newly hatched chickens results in extensive gut colonization and a strong adaptive immune stimulus but broiler chickens are immunologically immature. However, colonization exerts a variety of rapid (within 24 h) protective effects. These include specific colonization-inhibition (competitive exclusion) in which the protective bacteria exert a profound resistance to establishment and colonization by other related bacteria. This is thought to be primarily a metabolic attribute of the vaccinating bacteria but may also involve competition for attachment sites. The presence of large numbers of bacteria originating from a live Salmonella vaccine in the intestine can also induce infiltration of polymorphonuclear cells into the intestinal wall, which confers resistance to invasion and systemic spread by virulent Salmonella strains. This opens new perspectives for vaccine usage in broilers, layers and breeding poultry but also in other animals which show increased susceptibility to infection because of their young age or for other reasons, such as oral chemoprophylaxis or chemotherapy, where the lack of established normal gut flora is an issue. We recommend that all live vaccines considered for oral administration should be tested for their ability to induce the two protective effects described above. Further developments in live Salmonella vaccines are, however, currently hindered by fears associated with the use and release of live vaccines which may be genetically modified.

To study the dissemination of Mycobacterium bovis subsp. caprae, 79 European isolates from cattle, humans, and other hosts were examined by spoligotyping and IS6110 restriction fragment length polymorphism (RFLP) analysis. Among a total of 11 different spoligotypes identified, type C1 proved to be predominant (n ‫؍‬ 62). Five of the spoligotypes are described for the first time. A total of 43 different RFLP types were identified, thus allowing further differentiation for epidemiological tracking. Isolates from a series of outbreaks in one village proved to be of the same spoligotype and of identical or closely related RFLP types. Mycobacterium bovis subsp. caprae is a member of the M. tuberculosis complex, which also includes M. tuberculosis, M. africanum, M. bovis, M. bovis BCG, M. microti, and M. canettii.General interest in this pathogen, which was isolated from tuberculous lesions in humans, cattle, goats, sheep, and deer, has been steadily increasing since its first description (3). Thus, the prevalence of M. bovis subsp. caprae was extensively studied in Spain (4, 7) and France (8). There have been several reports about its occurrence in animals and humans in Austria (18) and the Czech Republic (15,16,17) and also in Germany (13), where it is reported to account for about one-third of human M. bovis-associated cases of tuberculosis (10).Identification of the various M. tuberculosis complex organisms by spoligotyping (9, 12) is performed on the basis of the presence or absence of certain combinations of 43 spacers which are interspersed among a high number of conserved repeats in the chromosomal direct-repeat region. Additional intraspecies genetic differences can be revealed by IS6110 fingerprinting or IS6110 restriction fragment length polymorphism (RFLP) analysis (19), which takes advantage of the mobility of insertion element IS6110 along the mycobacterial chromosome.The combination of spoligotyping and IS6100 RFLP can be expected to improve the possibilities of revealing epidemiological relationships because of the different discriminatory potential of both methods (18). Recent studies of serial isolates of M. tuberculosis clearly showed that due to the relatively frequent occurrence of IS6110 transposition events, IS6100 RFLP patterns were more likely to change within a few years of a strain's appearance than spoligotyping patterns (1,6,20).

Twenty-four-hour-old, aerobically grown, Luria-Bertani broth cultures of Salmonella typhimurium F98 suppressed the growth of a spectinomycin-resistant (Spc r ) derivative of the same strain inoculated at 10 3 CFU ml ؊1 . This growth suppression is genus specific and RpoS independent, and it is not solely a result of nutrient depletion (P. A. Barrow, M. A. Lovell, and L. Zhang-Barber, J. Bacteriol. 178:3072-3076, 1996). Mutations in three genes are shown here to significantly reduce growth suppression under these conditions. The mutations were located in the nuo, cyd, and unc operons, which code for the NADH dehydrogenase I, cytochrome d oxidase, and F 0 F 1 proton-translocating ATPase complexes, respectively. When cultures were grown under strictly anaerobic conditions, only the unc mutant did not suppress growth. Prior colonization of the alimentary tract of newly hatched chickens with the S. typhimurium F98 wild type or nuo or cyd mutants suppressed colonization by an S. typhimurium F98 Spc r derivative inoculated 24 h later. In contrast, the S. typhimurium unc mutant did not suppress colonization. The nuo and unc mutants showed poorer growth on certain carbon sources. The data support the hypothesis that growth suppression operates because of the absence of a utilizable carbon source or electron acceptor.The normal microbial flora of the alimentary tract is a major factor protecting animals and humans against colonization by pathogenic bacteria (17). Newly hatched chickens without an established flora are particularly susceptible to Salmonella infection and colonization. Colonized young chicks often excrete large numbers of salmonellae into their environment for long periods, thus becoming a potential reservoir of infection (7). When chickens reach several weeks of age, the lower alimentary tract is colonized by large numbers of obligate anaerobes which confer increased resistance to the establishment of Salmonella infection. The resistance of young chicks to infection may be artificially increased by oral administration, immediately after hatching, of a suspension or culture of cecal contents obtained from healthy adult birds (23). This phenomenon has been termed "competitive exclusion," and its discovery has led to a search for individual strains of bacteria which can inhibit colonization by pathogens to the same extent as the normal flora. Oral administration of an avirulent Salmonella typhimurium strain to day-old chicks can confer protection against oral infection by a virulent strain (known as colonization inhibition) (8, 10). Colonization inhibition is normally genus specific, is not caused by bacteriophage or bacteriocin activity, and is not a consequence of immunity induced by the first strain (8). Attempts are currently under way to elucidate the mechanisms responsible for this effect. An analogous phenomenon in vitro has been observed with 24-h-old stationaryphase nutrient broth cultures of S. typhimurium (6,8,11). When such cultures are inoculated with small numbers of genetically tagged (antibiot...