Molecular Typing of Mycobacterium bovis Isolates from Cameroon

Abstract

In order to gain a better understanding of the molecular epidemiology of Mycobacterium bovis isolates in Cameroon, 75 isolates of M. bovis collected in three provinces of northern Cameroon were studied by spoligotyping. For 65 of these isolates, typing was also carried out by pulsed-field gel electrophoresis (PFGE) with DraI, and 18 of the isolates were also typed by restriction fragment length polymorphism (RFLP) analysis with probe IS6110-RHS. Molecular typing of the isolates by these techniques revealed a high degree of homogeneity, with 10 spoligotypes for 75 isolates, four PFGE profiles for 65 isolates, and three RFLP types for 18 isolates. Some types were present in the three different provinces, while some were confined to one or two areas. These results suggest that geographical mapping of M. bovis strains could be helpful for the control of bovine tuberculosis at the regional level. An interesting feature of all the spoligotypes was the absence of spacer 30, suggesting a common origin for all of the Cameroon isolates tested; an evolutionary scenario for the isolates is discussed. In addition, a comparison of the three techniques showed that for M. bovis strain differentiation in Cameroon and in surrounding countries, spoligotyping would be a more discriminating and practical tool for molecular typing than the other two techniques used in this study.Bovine tuberculosis (TB) is endemic in many African countries, but economic constraints preclude the use of skin test and slaughter control strategies, which have proved effective in the developed world. In Cameroon, the majority of cattle herds are concentrated in the north (13), which is surrounded by Nigeria, Chad, and the Central African Republic. From visible lesion data obtained in the main slaughterhouses, it would appear that the prevalence of bovine TB in Cameroon is high (7). In addition, frequent cattle movement across the different areas of the country and across frontiers favors strain dissemination. In order to reduce the transmission of bovine TB, a bill from the Ministry of Livestock, Fisheries, and Animal Industries of Cameroon (no. 76/420) was introduced in 1976 to prevent the circulation of cattle between Adamaoua and the other two areas of northern Cameroon, i.e., Extreme North and North. This action resulted in the isolation of cattle within Adamaoua.To date, few studies have been performed to determine the correct prevalence of Mycobacterium bovis infection at local and regional levels (3,16,17,19), and there are no available data regarding the variability of M. bovis isolates within Cameroon. The aim of this study was to apply a number of molecular typing techniques to M. bovis isolates from different slaughterhouses located in three different provinces of northern Cameroon-North, Extreme North, and Adamaoua-in order gain a better understanding of the geographical distribution of M. bovis strains. The typing techniques used in this study were spoligotyping (11), pulsed-field gel electrophoresis (PFGE) (14) and, for some isolates, restri...

Molecular epidemiology of human and animal tuberculosis in Ibadan, Southwestern Nigeria

“…It was shown that M. bovis was isolated from 5% of human isolates in Ibadan (Cadmus et al, 2006). Furthermore, spoligotype profiles of some M. bovis strains isolated in Nigeria had been previously reported by earlier studies in Cameroon (Njanpop-Lafourcade et al, 2001). In Mali, a strain with a similar spoligopattern to SB0944, reported previously in Nigeria, Chad and Cameroon was also observed in 13 of the 20 strains studied (Muller et al, 2008).…”

Molecular Analysis of Human and Bovine Tubercle Bacilli from a Local Setting in Nigeria

“…The four M. bovis spoligotype patterns were compared with the M. bovis spoligotype database (www.mbovis .org) to determine whether they had been previously described. Two patterns (SB0944 and SB0952) had been previously described by Njanpop-Lafourcade and colleagues (14) in a survey of M. bovis isolates from Cameroon, a country neighboring Nigeria. The remaining two patterns did not appear in the database and were therefore designated N4 and N5.…”

Spoligotype Diversity of Mycobacterium bovis Strains Isolated in France from 1979 to 2000

“…This is illustrated by two elements. First, the total number of spoligotypes is very high, relative to the total number of typed isolates, when compared to many other locations, especially islands like Great Britain (10) or Australia (12) and developing countries like Cameroon (31) or Tanzania (27). Second, the frequency of the two main spoligotypes (BCG-like and GB54) is low compared to studies in other countries.…”

“…As the BCG-like profile is the most conserved within the M. bovis subspecies in terms of the number of spacers, the hypothesis of an ancestral status of this profile is also corroborated by the accepted concept that the evolution of the DR region occurs by spacer deletions (15). It has also been sug-gested in the case of Cameroon that a BCG-like strain has constituted the parental strain for the M. bovis strains presently isolated in Cameroon, due to the similarity of the dominant spoligotype in this country with BCG-like (31).…”

“…For a more practical point of view, it is interesting to observe that for French isolates the spoligotyping technique offers a rather high level of discrimination compared to some other countries (10,12,27,31). As a screening technique, it appears to be very useful and can even be used for the spatial (geotyping) and temporal (chronotyping) traceability of outbreaks, to a certain extent, at least if rare spoligotypes are involved.…”