Evaluation of the discriminatory power of variable number of tandem repeat typing of Mycobacterium bovis isolates from southern Africa

Whole genome sequencing improves the discrimination between Mycobacterium bovis strains on the southern border of Kruger National Park, South Africa

Background

Mycobacterium bovis forms part of the Mycobacterium tuberculosis complex and has an extensive host range and zoonotic potential. Various genotyping methods (e.g., spoligotyping) have been used to describe the molecular epidemiology of M. bovis. Advances in whole genome sequencing (WGS) have increased resolution to enable detection of genomic variants to the level of single nucleotide polymorphisms. This is especially relevant to One Health research on tuberculosis which benefits by being able to use WGS to identify epidemiologically linked cases, especially recent transmission. The use of WGS in molecular epidemiology has been extensively used in humans and cattle but is limited in wildlife. This approach appears to overcome the limitations of conventional genotyping methods due to lack of genetic diversity in M. bovis.

Methods

This pilot study investigated the spoligotype and WGS of M. bovis isolates (n = 7) from wildlife in Marloth Park (MP) and compared these with WGS data from other South African M. bovis isolates. In addition, the greater resolution of WGS was used to explore the phylogenetic relatedness of M. bovis isolates in neighbouring wildlife populations.

Results

The phylogenetic analyses showed the closest relatives to the seven isolates from MP were isolates from wildlife in Kruger National Park (KNP), which shares a border with MP. However, WGS data indicated that the KNP and MP isolates formed two distinct clades, even though they had similar spoligotypes and identical in silico genetic regions of difference profiles.

Conclusions

Mycobacterium bovis isolates from MP were hypothesized to be directly linked to KNP wildlife, based on spoligotyping. However, WGS indicated more complex epidemiology. The presence of two distinct clades which were genetically distinct (SNP distance of 19-47) and suggested multiple transmission events. Therefore, WGS provided new insight into the molecular epidemiology of the M. bovis isolates from MP and their relationship to isolates from KNP. This approach will facilitate greater understanding of M. bovis transmission at wildlife-livestock-human interfaces and advances One Health research on tuberculosis, especially across different host species.

Insight into the genetic diversity of Mycobacterium bovis isolated from cattle in Malawi

We describe the genetic diversity and phylogenetic relationships of Mycobacterium bovis, isolated from cattle in Malawi. Deletion analysis, spoligotyping, and MIRU-VNTR typing were used to genotype the isolates. Combined with a larger dataset from neighboring countries, the overall M. bovis diversity in Southern Africa was contextualized. From the southern and northern regions of Malawi, 24 isolates were confirmed as M. bovis. We pooled data for the central region (60 isolates) from our recent publication to conceptualize the genetic and phylogenetic relationships of M. bovis in Malawi. European 1 was the dominant M. bovis clonal complex, with 10 unique spoligotype patterns, and SB0131 was ubiquitous. High genetic diversity, a low clustering rate, and many singletons, coupled with a low mutation transmission index, infer a low level of recent transmission, and suggest an endemic status of bovine tuberculosis (bTB) in Malawi. M. bovis isolates from Zambia, Mozambique, and South Africa were genetically related to Malawian isolates, whereas Tanzanian isolates were distantly related. The diversity and phylogenetic analysis suggest earlier introductions and maintenance of M. bovis by constant reinfection from reservoir animals. These findings are fundamental to understanding the source and route of infection in order to establish alternative management strategies for bTB.

Evidence, Challenges, and Knowledge Gaps Regarding Latent Tuberculosis in Animals

Mycobacterium bovis and other Mycobacterium tuberculosis complex (MTBC) pathogens that cause domestic animal and wildlife tuberculosis have received considerably less attention than M. tuberculosis, the primary cause of human tuberculosis (TB). Human TB studies have shown that different stages of infection can exist, driven by host-pathogen interactions. This results in the emergence of heterogeneous subpopulations of mycobacteria in different phenotypic states, which range from actively replicating (AR) cells to viable but slowly or non-replicating (VBNR), viable but non-culturable (VBNC), and dormant mycobacteria. The VBNR, VBNC, and dormant subpopulations are believed to underlie latent tuberculosis (LTB) in humans; however, it is unclear if a similar phenomenon could be happening in animals. This review discusses the evidence, challenges, and knowledge gaps regarding LTB in animals, and possible host-pathogen differences in the MTBC strains M. tuberculosis and M. bovis during infection. We further consider models that might be adapted from human TB research to investigate how the different phenotypic states of bacteria could influence TB stages in animals. In addition, we explore potential host biomarkers and mycobacterial changes in the DosR regulon, transcriptional sigma factors, and resuscitation-promoting factors that may influence the development of LTB.

Prevalence of bovine tuberculosis and characterization of the members of the Mycobacterium tuberculosis complex from slaughtered cattle in Rwanda

Background

Bovine tuberculosis (bTB) is an endemic disease in Rwanda, but little is known about its prevalence and causative mycobacterial species. The disease causes tremendous losses in livestock and wildlife and remains a significant threat to public health.

Materials and methods

A cross-sectional study employing a systematic random sampling of cattle (n = 300) with the collection of retropharyngeal lymph nodes and tonsils (n = 300) irrespective of granulomatous lesions was carried out in six abattoirs to investigate the prevalence and identify mycobacterial species using culture, acid-fast bacteria staining, polymerase chain reaction, and GeneXpert assay. Individual risk factors and the origin of samples were analysed for association with the prevalence.

Findings

Of the 300 sample pools, six were collected with visible TB-like lesions. Our findings demonstrated the presence of Mycobacterium tuberculosis complex (MTBC) in 1.7% (5/300) of sampled slaughtered cattle. Mycobacterium bovis was isolated from 1.3% (4/300) animals while one case was caused by a rifampicin-resistant (RR) M. tuberculosis. Non-tuberculous mycobacteria were identified in 12.0% (36/300) of the sampled cattle. There were no significant associations between the prevalence and abattoir category, age, sex, and breeds of slaughtered cattle.

Conclusions

This study is the first in Rwanda to isolate both M. bovis and RR M. tuberculosis in slaughtered cattle indicating that bTB is present in Rwanda with a low prevalence. The isolation of RR M. tuberculosis from cattle indicates possible zooanthroponotic transmission of M. tuberculosis and close human-cattle contact. To protect humans against occupational zoonotic diseases, it is essential to control bTB in cattle and raise the awareness among all occupational groups as well as reinforce biosafety at the farm level and in the abattoirs.

Tuberculosis in cattle (bTB) causes financial losses to livestock owners and is a disease transmissible to humans especially those with an occupational risk through exposure to infected animals and animal products. This study aimed to identify the prevalence of bTB and characterize the mycobacterial species from cattle slaughtered in the six abattoirs in Rwanda. Four M. bovis, as well as one rifampicin-resistant (RR) M. tuberculosis, were identified from slaughtered cattle and, thus, the apparent bTB prevalence was 1.7% (5/300). Likely, the RR M. tuberculosis isolate was mostly likely of human origin and transmitted to cattle during close human-cattle contact. It is therefore essential to control bTB in cattle and reinforce the protection of farmworkers and abattoir workers who are always exposed to infected animals.

Bovine tuberculosis in Taiwan, 2008-2019

Bovine tuberculosis (bTB) is a zoonosis caused by Mycobacterium bovis. The impact of bTB on global TB control has been underestimated. We adopted the One Health approach to human bTB surveillance in Taiwan. Of 20,972 human TB cases, 202 (1.0%) were bTB, 78.2% were in males, 85.1% were new cases, 83.2% were pulmonary TB, and most were in Central (52.5%) and Southern (24.8%) Taiwan. Only 18.8% of bTB patients had known animal contact. Of the 202 human M. bovis strains, 100% were resistant to pyrazinamide (PZA), 30.2% were concurrently resistant to isoniazid (INH) and 2.0% were multidrug resistant, defined as being resistant to at least INH and rifampin. Whereas, of the 22 animal M. bovis strains, 100% and 22.7% were resistant to PZA and INH, respectively. Seven spoligotypes and 25 mycobacterial interspersed repetitive unit genotypes were identified. The predominant genotype, SB0265, was also prevalent in livestock. Notably, six animal-specific M. bovis genotypes were identified. bTB differential diagnosis and drug resistance detection are crucial for TB control. Comprehensive surveillance and human-animal interface investigations are needed.

Tracing cross species transmission of Mycobacterium bovis at the wildlife/livestock interface in South Africa

BACKGROUND

Bovine tuberculosis (bTB) affects cattle and wildlife in South Africa with the African buffalo (Syncerus caffer) as the principal maintenance host. The presence of a wildlife maintenance host at the wildlife/livestock interface acting as spill-over host makes it much more challenging to control and eradicate bTB in cattle. Spoligotyping and mycobacterial interspersed repetitive unit-variable number of tandem repeat (MIRU-VNTR) genotyping methods were performed to investigate the genetic diversity of Mycobacterium bovis (M. bovis) isolates from cattle and wildlife, their distribution and transmission at the wildlife/livestock interface in northern Kwa-Zulu Natal (KZN), South Africa.

RESULTS

SB0130 was identified as the dominant spoligotype pattern at this wildlife/livestock interface, while VNTR typing revealed a total of 29 VNTR profiles (strains) in the KZN province signifying high genetic variability. The detection of 5 VNTR profiles shared between cattle and buffalo suggests M. bovis transmission between species. MIRU-VNTR confirmed co-infection in one cow with three strains of M. bovis that differed at a single locus, with 2 being shared with buffalo, implying pathogen introduction from most probably unrelated wildlife sources.

CONCLUSION

Our findings highlight inter and intra species transmission of bTB at the wildlife/livestock interface and the need for the implementation of adequate bTB control measures to mitigate the spread of the pathogen responsible for economic losses and a public health threat.

Challenges for controlling bovine tuberculosis in South Africa

All effects taken together, bovine tuberculosis (bTB) has a long-term detrimental effect on bovine herds and many wildlife species in South Africa. The disease is not only found in domestic cattle but also in African buffaloes and has to date been diagnosed in 21 wildlife species, including several rare and endangered species, thus having a potentially serious effect on conservation and biodiversity. In cattle, bTB is mostly characterised by sporadic outbreaks, but bovine herds chronically infected with the clinical disease are not uncommon. Presently, the recognised bTB control strategy in South Africa is based on 'test and slaughter', using the intradermal tuberculin test, followed by the slaughter of animals that have tested positive. Affected herds are placed under veterinary quarantine with movement restrictions until the outbreak is eradicated; this can take several years or last indefinitely if the outbreak cannot be eradicated. The same measures apply to infected buffalo populations, often with no prospect of ever being eradicated. This strategy is neither practical nor viable in the context of a communal farming system and becomes unethical when dealing with valuable wildlife reservoir hosts. Transmission of bTB between wildlife and cattle has been demonstrated and emphasises the need for an effective, affordable and culturally acceptable control strategy to curb the spread of bTB in South Africa. In countries with similar challenges, vaccination has been used and found to be promising for treating wild and domestic reservoir species and may hence be of value as a complementary tool for bTB control in South Africa.

Risk Factors for Zoonotic Tuberculosis at the Wildlife-Livestock-Human Interface in South Africa

A cross-sectional study was conducted to investigate the risk factors associated with zoonotic tuberculosis in humans and its transmission to people living at the wildlife–livestock–human interface. A questionnaire was administered to collect information on food consumption habits, food handling practices, and knowledge of zoonotic TB. Sputum samples were also collected from 150 individuals that belonged to households of cattle farmers with or without a bTB infected herd. In addition, 30 milk samples and 99 nasal swabs were randomly collected from cattle in bTB infected herds for isolation of Mycobacterium bovis (M. bovis). The sputum samples were screened for TB using the GeneXpert test and this was followed by mycobacterial culture and speciation using molecular techniques. No M. bovis was isolated from TB positive sputum samples and only one sample was confirmed as Mycobacterium tuberculosis (M. tuberculosis). M. bovis was isolated from 6.6% (n = 2/30) milk samples and 9% (n = 9/99) of nasal swabs. Ownership of a bTB infected herd and consumption of milk were recognized as highly significant risk factors associated with a history of TB in the household using multiple correspondence analysis (MCA) and logistic regression. The findings from this study have confirmed the potential for zoonotic TB transmission via both unpasteurized milk and aerosol thus, the role of M. bovis in human TB remains a concern for vulnerable communities.

First detection of Mycobacterium bovis infection in Giraffe (Giraffa camelopardalis) in the Greater Kruger National Park Complex: Role and implications

Bovine tuberculosis (bovine TB) caused by Mycobacterium bovis has become endemic in some wildlife populations in South Africa. The disease has been reported in 21 wildlife species in the country. In this study, we report M. bovis infection in two female giraffes (Giraffa camelopardalis) from two different nature reserves within the Greater Kruger National Park Complex (GKNPC). Mycobacterium bovis was isolated from tissue lesions consistent with macroscopic appearance of tuberculosis (TB) and confirmed by polymerase chain reactions (PCRs), targeting the RD4 region of difference on the genome of the isolates. Spoligotyping and variable number of tandem repeat (VNTR) typing revealed infection of one giraffe with a strain (SB0294) previously not detected in South Africa, while a resident M. bovis strain (SB0121) was detected from the other giraffe. Our work is first to report M. bovis infection in free-ranging giraffes in South Africa. We have further demonstrated the existence of at least three genetically unrelated strains currently infecting wildlife species within the GKNPC. This finding suggests that the epidemiological situation of M. bovis within the GKNPC is not only driven by internal sources from its established endemic presence, but can be additionally fuelled by strains introduced from external sources. It further emphasizes that regular wildlife disease surveillance is an essential prerequisite for the timely identification of new pathogens or strains in ecospheres of high conservation value.

Prevalence of Mycobacterium bovis infection in traditionally managed cattle at the wildlife-livestock interface in South Africa in the absence of control measures

Cattle are the domestic animal reservoir for Mycobacterium bovis (M. bovis) which also affects other domestic animals, several wildlife species and humans leading to tuberculosis. The study area is in a resource-poor community that is surrounded by several game parks, where M. bovis infection has been previously diagnosed in wildlife. A cross-sectional study was carried out to determine the prevalence of M. bovis infection in 659 cattle from a total of 192 traditionally managed herds using the BOVIGAM® interferon gamma assay (IFN-γ). Infection was confirmed by post mortem examination and M. bovis isolation from three test-positive cattle. Genotyping of the M. bovis isolates was done using spoligotyping and VNTR (variable number of tandem repeats typing). The apparent M. bovis prevalence rate in cattle at animal level was 12% with a true population prevalence of 6% (95% Confidence interval (C.I) 3.8 to 8.1) and a herd prevalence of 28%. Spoligotyping analysis revealed that the M. bovis isolates belonged to spoligotype SB0130 and were shared with wildlife. Three VNTR profiles were identified among the SB0130 isolates from cattle, two of which had previously been detected in buffalo in a game reserve adjacent to the study area. The apparent widespread presence of M. bovis in the cattle population raises a serious public health concern and justifies further investigation into the risk factors for M. bovis transmission to cattle and humans. Moreover, there is an urgent need for effective bTB control measures to reduce infection in the communal cattle and prevent its spread to uninfected herds.

Mycobacterium bovis Persistence in Two Different Captive Wild Animal Populations in Germany: a Longitudinal Molecular Epidemiological Study Revealing Pathogen Transmission by Whole-Genome Sequencing

Bovine tuberculosis (bTB) caused by Mycobacterium bovis is a transmissible disease notifiable to the World Organization for Animal Health and to the European Union, with ongoing efforts of surveillance and eradication in every EU member state. In Germany, a country which has been declared officially free from bovine tuberculosis since 1997 by the EU, M. bovis infections still occur sporadically in cattle and other mammals, including humans. Here, the transmission routes of a bTB outbreak in a wildlife park in Germany affecting different cervid species, bison, lynx, and pot-bellied pigs were followed by employing whole-genome sequencing (WGS) combined with spoligotyping and mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) typing. One single M. bovis strain persisted from 2002 to 2015, and transmission between the park and a distantly located captive cervid farm was verified. The spoligotyping patterns remained identical, while MIRU-VNTR typing of 24 loci of the standardized panel and locus 2163a as an additional locus revealed one change at locus 2165 in a strain from a fallow deer and one at locus 2461 in isolates from red deer over the whole time period. WGS analysis confirmed the close relatedness of the isolates, with a maximum of 12 single nucleotide polymorphisms (SNPs) detected between any two sequenced isolates. In conclusion, our data confirm a longitudinal outbreak of M. bovis in a German wildlife park and provide the first insights into the dynamics of different genotyping markers in M. bovis.

Genetic profiling of Mycobacterium bovis strains from slaughtered cattle in Eritrea

Mycobacterium bovis (M.bovis) is the main causative agent for bovine tuberculosis (BTB) and can also be the cause of zoonotic tuberculosis in humans. In view of its zoonotic nature, slaughterhouse surveillance, potentially resulting in total or partial condemnation of the carcasses and organs, is conducted routinely. Spoligotyping, VNTR profiling, and whole genome sequencing (WGS) of M. bovis isolated from tissues with tuberculosis-like lesions collected from 14 cattle at Eritrea’s largest slaughterhouse in the capital Asmara, were conducted.The 14 M. bovis isolates were classified into three different spoligotype patterns (SB0120, SB0134 and SB0948) and six VNTR profiles. WGS results matched those of the conventional genotyping methods and further discriminated the six VNTR profiles into 14 strains. Furthermore, phylogenetic analysis of the M. bovis isolates suggests two independent introductions of BTB into Eritrea possibly evolving from a common ancestral strain in Europe.This molecular study revealed the most important strains of M. bovis in Eritrea and their (dis)similarities with the strains generally present in East Africa and Europe, as well as potential routes of introduction of M. bovis. Though the sample size is small, the current study provides important information as well as platform for future in-depth molecular studies on isolates from both the dairy and the traditional livestock sectors in Eritrea and the region. This study provides information onthe origin of some of the M. bovis strains in Eritrea, its genetic diversity, evolution and patterns of spread between dairy herds. Such information is essential in the development and implementation of future BTB control strategy for Eritrea.

The livestock sector plays a major role in poverty and hunger reduction in the vast majority of Africa, as a source of food, cash income, manure, draught power, transportation, savings, insurance and social status. However, for livestock to play this vital role, the impact of diseases of economic and zoonotic importance need to be reduced. Bovine tuberculosis, mainly caused by Mycobacterium bovis, is such an infectious disease. Slaughterhouse (gross pathology) surveillance, followed by bacterial culture and genotyping, are options to identify the disease-causing agents, their distribution, and enabling trace back of the sources of infections, in order to prevent their re-introduction and spread. Unfortunately, genotyping is by far not generally introduced in the continent. In the present study, tissues with tuberculosis-like lesions were collected from the Asmara municipal slaughterhouse, the largest slaughterhouse in Eritrea, and bacterial culture, classical Mycobacterium tuberculosis complex typing (Spoligotyping and VNTR profiling), as well as whole genome sequencing (WGS) were used to gain insight into the spatial and temporal distribution, genetic diversity and evolution of M. bovis strains circulating in Eritrean dairy cattle. The results revealed (dis)similarities of the Eritrean M. bovis strains with the strains generally present in Africa and Europe, potential routes of introduction to Eritrea and genetic diversity of the M. bovis strains. Future in-depth molecular studies including more samples from dairy cattle as well as cattle and goats from the traditional livestock sector are recommended.

The most common spoligotype of Mycobacterium bovis isolated in the world and the recommended loci for VNTR typing; A systematic review

Mycobacterium bovis is a neglected zoonotic organism that epidemiological studies are of crucial importance in identifying its source, control it and prevent it from spreading. The aim of this study was to investigate the most common spoligotypes of Mycobacterium bovis circulating around the world and introduce the most and least strong determine powers of loci for VNTR. We have used different databases such as ISC, science direct, Embase (Elsevier), Web of Science, Scopus and Medline via PubMed. Searches were performed by key words including: Mycobacterium bovis, MIRU -VNTR, spoligotyping and discrimination power. Finally, thirty-one articles were selected after filtering out some titles, abstracts and full texts. Spoligotype SB0120 was the most common circulating type on several continents while SB0121 existed in Europe, Africa and America. SB0140 was also detected in Asia, Europe and America. QUB3232 and QUB11b were more appropriate loci among the loci with high discriminatory power. MIRU 10 and MIRU4 were among the loci with poor discriminatory power. Taking the published data into consideration, SB0120 and SB0121 are predominant spoligotypes of M. bovis circulating among animals around the world. Determining the most common spoligotype of M. bovis is the key to find source of infection, control and prevent the disease.

Genetic diversity and potential routes of transmission of Mycobacterium bovis in Mozambique

Bovine tuberculosis is a zoonotic disease with largely unknown impact in Africa, with risk factors such as HIV and direct contact with animals or consumption of Mycobacterium bovis infected animal products. In order to understand and quantify this risk and design intervention strategies, good epidemiological studies are needed. Such studies can include molecular typing of M. bovis isolates. The aim of this study was to apply these tools to provide novel information concerning the distribution of bovine tuberculosis in cattle in Mozambique and thereby provide relevant information to guide policy development and strategies to contain the disease in livestock, and reduce the risk associated with transmission to humans. A collection of 178 M. bovis isolates was obtained from cattle in Mozambique. Using spoligotyping and regions of difference analysis, we classified the isolates into clonal complexes, thus reporting the first characterisation of M. bovis strains in this region. Data from MIRU-VNTR typing was used to compare isolates from a number of African countries, revealing a deeply geographically structured diversity of M. bovis. Eastern Africa appears to show high diversity, suggesting deep evolution in that region. The diversity of M. bovis in Africa does not seem to be a function of recent importation of animals, but is probably maintained within each particular region by constant reinfection from reservoir animals. Understanding the transmission routes of M. bovis in Mozambique and elsewhere is essential in order to focus public health and veterinary resources to contain bovine tuberculosis.

Bovine tuberculosis is a rather neglected zoonotic disease caused by Mycobacterium bovis that is of global concern owing to the persistence of the bacillus in reservoirs that can spread bovine tuberculosis between animals and humans. Africa remains understudied regarding this pathogen, and should be an area of concern given that in many regions the consumption of raw milk or meat from infected animals persists and the presence of HIV infection renders the population more susceptible. In order to control the disease, we need to understand M. bovis epidemiology, which includes the sources of infection. The important conclusion drawn from the work presented here is that there is a strong association between M. bovis genetic characteristics and geography. This implies that the diversity of M. bovis isolates in Mozambique does not seem to be caused by recent introductions to the territory, but is probably maintained within reservoirs in each particular region.

Genotypes of Mycobacterium bovis strains isolated from domestic animals and wildlife in Canada in 1985-2015

Two internationally recognised and standardised genotyping methods, mycobacterial interspersed repetitive unit and variable number tandem repeat analysis (MIRU-VNTR) and spoligotyping, were applied to characterise genetic variations among 137 Mycobacterium bovis isolates recovered from Canadian domestic and wild animals during 1985-2015. Spoligotyping generated seven types that were discriminated further into12 MIRU-VNTR types. The discriminatory power indexes were estimated as 0.71 and 0.77 for spoligotyping and MIRU-VNTR typing approaches, respectively. In total, 6 prominent clusters of isolates were observed by the genotyping schemes. Four genotype clusters were exclusively observed in farmed animals. Three of these four clusters were affiliated with localised tuberculosis outbreaks, and each cluster corresponded to a single specific spoligotype (SB0140, SB0673, and SB1069) and a MIRU-VNTR profile. The fourth genotype cluster, with spoligotype SB0265 which segregated into two MIRU-VNTR types, was associated with bovine tuberculosis outbreaks in several farms across Canada during 1990-2002. Two genotype clusters of M. bovis stains were associated with wildlife reservoirs: a spoligotype SB0130 with 3 unique MIRU-VNTR profiles were observed in wood bison in Wood Buffalo National Park, and unique spoligotypes SB1070 and 1071 represented by four MIRU-VNTR profiles were recovered from cervidae species in and around the Riding Mountain National Park of Manitoba. Genotyping data confirmed M. bovis transmission between wildlife and livestock in Manitoba in 1990-2008. Overall, notwithstanding the low level of genetic diversity of Canadian M. bovis strains, the spoligotyping and MIRU-VNTR typing were useful tools in monitoring transmission of endemic strains and defining new introductions to Canada. The majority of genotypes were most likely introduced into domestic animals through live animal trade, and subsequently eliminated as a result of bovine tuberculosis outbreak investigation and eradication activities.

Mycobacterium tuberculosis infection in cattle from the Eastern Cape Province of South Africa

Background

Mycobacterium tuberculosis is the main causative agent of tuberculosis (TB) in human and Mycobacterium bovis commonly causes tuberculosis in animals. Transmission of tuberculosis caused by both pathogens can occur from human to animals and vice versa.

Results

In the current study, M. tuberculosis, as confirmed by polymerase chain reaction (PCR) using primers targeting 3 regions of difference (RD4, RD9 and RD12) on the genomes, was isolated from cattle originating from two epidemiologically unrelated farms in the Eastern Cape (E.C) Province of South Africa. Although the isolates were genotyped with variable number of tandem repeat (VNTR) typing, no detailed epidemiological investigation was carried out on the respective farms to unequivocally confirm or link humans as sources of TB transmission to cattle, a move that would have embraced the ‘One Health’ concept. In addition, strain comparison with human M. tuberculosis in the database from the E.C Province and other provinces in the country did not reveal any match.

Conclusions

This is the first report of cases of M. tuberculosis infection in cattle in South Africa. The VNTR profiles of the M. tuberculosis strains identified in the current study will form the basis for creating M. tuberculosis VNTR database for animals including cattle for future epidemiological studies. Our findings however, call for urgent reinforcement of collaborative efforts between the veterinary and the public health services of the country.

Isolation and Potential for Transmission of Mycobacterium bovis at Human-livestock-wildlife Interface of the Serengeti Ecosystem, Northern Tanzania

Mycobacterium bovis, the causative agent of bovine tuberculosis (bTB), is a multihost pathogen of public health and veterinary importance. We characterized the M. bovis isolated at the human-livestock-wildlife interface of the Serengeti ecosystem to determine the epidemiology and risk of cross-species transmission between interacting hosts species. DNA was extracted from mycobacterial cultures obtained from sputum samples of 472 tuberculosis (TB) suspected patients and tissue samples from 606 livestock and wild animal species. M. bovis isolates were characterized using spoligotyping and Mycobacterial Interspersed Repetitive Units-Variable Tandem Repeats (MIRU-VNTR) on 24 loci. Only 5 M. bovis were isolated from the cultured samples. Spoligotyping results revealed that three M. bovis isolates from two buffaloes (Syncerus caffer) and 1 African civet (Civettictis civetta) belonged to SB0133 spoligotype. The two novel strains (AR1 and AR2) assigned as spoligotype SB2290 and SB2289, respectively, were identified from indigenous cattle (Bos indicus). No M. bovis was detected from patients with clinical signs consistent with TB. Of the 606 animal tissue specimens and sputa of 472 TB-suspected patients 43 (7.09%) and 12 (2.9%), respectively, yielded non-tuberculous mycobacteria (NTM), of which 20 isolates were M. intracellulare. No M. avium was identified. M. bovis isolates from wildlife had 45.2% and 96.8% spoligotype pattern agreement with AR1 and AR2 strains, respectively. This finding indicates that bTB infections in wild animals and cattle were epidemiologically related. Of the 24 MIRU-VNTR loci, QUB 11b showed the highest discrimination among the M. bovis strains. The novel strains obtained in this study have not been previously reported in the area, but no clear evidence for recent cross-species transmission of M. bovis was found between human, livestock and wild animals.

Extracts of six Rubiaceae species combined with rifampicin have good in vitro synergistic antimycobacterial activity and good anti-inflammatory and antioxidant activities

Background

The Rubiaceae family has played a significant role in drug discovery by providing molecules with potential use as templates for the development of therapeutic drugs. This study was designed to study the in vitro synergistic effect of six Rubiaceae species in combination with a known anti-TB drug. The antioxidant and anti-inflammatory activity of these species were also evaluated to investigate additional benefits in antimycobacterial treatment.

Methods

The checkerboard method was used to determine the antimycobacterial synergistic activity of plant extracts combined with rifampicin. The antioxidant activity of extracts was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Anti-inflammatory activity via inhibition of nitric oxide (NO) production was performed in LPS-activated RAW 264.7 macrophages using the Griess assay.

Results

Combination of rifampicin with the crude extracts resulted in a 4 to 256-fold increase of activity of extracts. The crude extract of Cremaspora triflora produced the best synergistic effect with rifampicin, with a fractional inhibitory concentration (FIC) index of 0.08 against Mycobacterium aurum. Extracts of Psychotria zombamontana had the best antioxidant activity with an IC₅₀ value of 1.77 μg/mL, lower than the IC₅₀ of trolox and ascorbic acid (5.67 μg/mL and 4.66 μg/mL respectively). All the extracts tested inhibited nitric oxide (NO) production in a concentration dependent manner with the percentage of inhibition varying from 6.73 to 86.27 %.

Conclusion

Some of the Rubiaceae species investigated have substantial in vitro synergistic effects with rifampicin and also good free radical scavenging ability and anti-inflammatory activity. These preliminary results warrant further study on these plants to determine if compounds isolated from these species could lead to the development of bioactive compounds that can potentiate the activity of rifampicin even against resistant mycobacteria.

Isolation and molecular characterization of Mycobacterium bovis causing pulmonary tuberculosis and epistaxis in a Thoroughbred horse

BACKGROUND

Tuberculosis caused by Mycobacterium bovis (M. bovis) is very uncommon in horses worldwide.

CASE PRESENTATION

In the current study, an eight-year-old male Thoroughbred in good body condition was admitted to the Equine Clinic at the Onderstepoort Veterinary Academic Hospital in 2005 due to bilateral epistaxis accompanied by coughing. Routine examinations were conducted to determine the cause of the condition. Endoscopic examination revealed the major source of the epistaxis as the trachea, whereas thoracic radiography indicated the presence of a primary pulmonary mass. M. bovis was isolated from a broncho-alveolar lavage (BAL) sample collected. The pulmonary mass reduced in size three months later following an oral administration of enrofloxacin (7.5 mg/kg PO SID). Genetic fingerprinting by spoligotyping identified the M. bovis isolate as spoligotype SB0868 strain. This M. bovis strain type was never described previously in South Africa (SA). This is the first case of M. bovis infection in a horse in SA which has been fully documented including clinical findings, isolation and genetic characterisation of the causative pathogen.

CONCLUSIONS

This report indicates that horses may contract and harbour M. bovis despite their lower susceptibility compared to other domestic animals. It also suggests that the infection may be more easily contained and eliminated from the host.

Spillover of Mycobacterium bovis from wildlife to livestock, South Africa

During August 2012–February 2013, bovine tuberculosis was detected in communal livestock bordering the Greater Kruger National Park Complex (GKNPC) in South Africa. Using spacer oligonucleotide and variable number tandem repeat typing, we identified the Mycobacterium bovis strain endemic in GKNPC wildlife. Our findings indicate bovine tuberculosis spillover from GKNPC wildlife to neighboring livestock.