No presenta resumen. / Revisión por pares

Cat scratch disease (CSD) is a self limited zoonotic disease that presents most commonly as a regional lymphadenopathy. We are reporting a case of a 25-year-old male patient who presented with fever and large right inguinal lymphadenopathy. The diagnosis of cat scratch disease was confirmed based on the characteristic cytopathological features on aspirate smears from the lymph node and the serological titers for Bartonella henselae. This case report emphasizes the importance of combining Bartonella serology, and cytopathology in the diagnostic work-up of febrile lymphadenopathy and suspected CSD since the culture of this organism is arduous.

Rodents have been reported to play a significant role as reservoirs of over 22 rodent-associated Bartonella species. In this study, we contrast prevalence and diversity of Bartonella infections in 377 small mammals, representative of three terrestrial rodent genera, namely Aethomys, Gerbilliscus and Rhabdomys and one subterranean mole-rat species (Bathyergus suillus). The latter was sampled in close proximity to an informal human settlement, whereas the afore-mentioned murid rodent genera were sampled across a range of landscapes inclusive of natural, agricultural, urban, peri-urban and rural settings, from three provinces (Free State, Gauteng and Western Cape) in South Africa. Molecular estimates of Bartonella infection rates were determined through multi-gene screening of DNA extracted from clinical samples, primarily heart and spleen. PCR assays targeting the citrate synthase (gltA) and NADH dehydrogenase gamma subunit (nuoG) and/or beta subunit of bacterial RNA polymerase (rpoB) genes were used to ensure enhanced molecular estimates of Bartonella prevalence. Aethomys had the highest infection rate (86.7%), whereas Rhabdomys had the lowest (15%). Nucleotide sequencing and phylogenetic analyses revealed that the different primers sets used for Bartonella screening have different affinities to the different strains present in rodents from South Africa. Furthermore, the presence of Bartonella co-infections, confirmed through the presence of multiple peaks at 15% of the nucleotide sequences sites, ranged from 33.8% (in Aethomys) to 42.9% (in Gerbilliscus species) for the gltA gene region. For Aethomys ineptus, of the discrete Bartonella lineages recovered, one was closely related to zoonotic B. elizabethae. The latter species, which is associated with Rattus hosts worldwide and has been linked to cases of human endocarditis, suggests spillover from invasive to indigenous rodents. This is supported by previous studies indicating that indigenous Micaelamys namaquensis, a highly adaptable species, which like Aethomys is capable of utilizing natural and modified landscapes also hosts B. elizabethae-related lineages. Of potential public health importance, Bathyergus suillus were shown to be infected with a zoonotic Bartonella species, B. rochalimae. Our results further indicate that the level of anthropogenic transformation is significantly correlated with Bartonella prevalence, with Rhabdomys sampled from rural settings in the Western Cape Province having infection rates of 36% versus 0% in a nearby urban setting. This study also uncovered high levels of strain diversity in members of the Gerbilliscus cryptic species complex, sampled from an agricultural setting. The overall Bartonella PCR-positivity rate was 67.5 % and the gltA gene phylogeny confirmed the presence of six discrete Bartonella gerbil-specific lineages (I-VI). Lineages I and II clustered with Bartonella strains identified previously in G. leucogaster sampled from Sandveld nature reserves in the Free State Province South Africa, whereas lineages III-VI comprised of lineages that were restricted to either G. leucogaster or to G. brantsii, indicative of host-specificity. From the findings of this study, it is clear that the public health importance of the Bartonella species present in indigenous rodents warrants further investigation as at least two species, with known zoonotic potential (B. elizabethae and B. rochalimae) were shown to be present in rodents sampled in close proximity to human settlements. / Thesis (PhD (Zoology))--University of Pretoria, 2019. / This research was made possible through the financial support from the (AZD-IRT), CDC Co-Ag 5 NU2GGH001874-02-00 and through the NRF incentive and SARChI PI funding awarded to ADSB. / Zoology and Entomology / PhD (Zoology) / Unrestricted

Bacterial genomes provide records of the molecular processes associated with emergence and evolution of different bacterial lifestyles. This thesis is based on whole-genome comparisons within the genus Bartonella, an excellent model system for studies of host- and vector-specificity and infection outcome in animal-associated bacteria. The louse-borne human specialist and trench fever agent Bartonella quintana was contrasted to the flea-borne generalist relatives Bartonella henselae and Bartonella grahamii, which cause asymptomatic infection in cat and mouse respectively. While B. henselae is commonly isolated from humans, and causes cat scratch disease, there is only one reported case of B. grahamii human infection. The gene complements of the three species are nested like Russian dolls with the smaller genome (B. quintana) being entirely contained in the medium sized (B. henselae), which in turned is contained in the largest (B. grahamii). Size differences reflect differences in the horizontally and vertically acquired gene content, and in the number of genus- and species- specific genes, owing to differential impact of bacteriophages and plasmids, and to different degrees of genome decay. These processes can be attributed to the three distinct lifestyles. Comparisons with other alpha-proteobacteria suggest that the Bartonella genus as a whole evolved from plant-associated species, and that horizontal transfer, in particular of genes involved in interaction with the host, played a key role in the transition to animal intracellular lifestyle. The long-term genome decay associated with this lifestyle is most advanced in the host-restricted B. quintana. The broad host-range species B. grahamii has the largest genome and the largest proportion of auxiliary DNA of the three, probably because it has access to a larger gene pool. In encodes all the known pathogenicity determinants found in the genomes of B. henselae and B. quintana, suggesting that these genes primarily evolved to facilitate colonization in the reservoir host.

Les Bartonelles sont des bactéries hémotropes responsables de zoonoses émergentes. Ces Alphaprotéobactéries sont auxotrophes pour l'hème et doivent donc l'importer du milieu extérieur pour croître. Les Bartonelles possèdent un système complet de transport de l'hème permettant de transporter ce composé dans le cytoplasme. Chez Bartonella, il a été montré que l'hème pouvait être utilisé comme source de fer. Comme pour d'autres bactéries utilisant l'hème comme une source de fer, Bartonella doit dégrader l'hème pour libérer le fer. Chez Bartonella, un ensemble de gènes codant pour le système de transport de l'hème, contient un gène codant pour un polypeptide (HemS) présentant des homologies avec des protéines liant ou dégradant l'hème. En utilisant des expériences de complémentation de mutants d'E. coli incapables de dégrader l'hème, nous avons mis en évidence que HemS de Bartonella henselae permet la libération du fer de l'hème. HemS purifié lie l'hème et le dégrade en présence de donneurs d'électrons. La diminution du niveau de HemS chez B. henselae décroit sa capacité de survivre à une exposition à H2O2. Les Bartonelles expriment quatre ou cinq protéines de la membrane externe ayant la capacité de fixer l'hème. Les gènes de structure de ces protéines sont exprimés différemment en fonction de paramètres comme la température ainsi que la concentration en oxygène ou en hème. Ces protéines ont été proposées comme étant impliquées dans divers processus cellulaires étant donné leur profil d'expression. Dans ce manuscrit, nous montrons que ces protéines sont impliquées dans la défense contre le stress oxydatif, la colonisation des cellules endothèliales et la survie dans la puce

Publicación a texto completo no autorizada por el autor / La enfermedad de Carrión, también llamada Bartonelosis es una enfermedad desatendida, presente en los países de Colombia, Ecuador y especialmente en Perú; causada por la bacteria Bartonella bacilliformis y transmitida por mosquitos del género Lutzomyia. Los flebotominos de las especies Lutzomyia verrucarum y Lutzomyia peruensis han sido descritos como los vectores principales de la enfermedad. Sin embargo, existen áreas endémicas de Bartonelosis en algunas regiones ubicadas al norte del Perú, en los departamentos de Cajamarca y Amazonas en donde no se han reportado la presencia de estos dos vectores pero se han reportado una gran abundancia de flebotominos de las especies Lutzomyia serrana y Lutzomyia maranonensis, las cuales podrían estar implicadas como potenciales vectores de la enfermedad de Carrión. El objetivo de este estudio fue evaluar molecularmente la presencia de B. bacilliformis en flebotominos de la especie L. maranonensis de 4 distritos de la provincia de Cutervo, departamento de Cajamarca, Perú. Esta especie aún no ha sido definida como portadora del agente etiológico. Se analizaron muestras de flebotonimos hembras adultas colectadas con trampas de luz de tipo CDC en los años 2007 y 2008. La comprobación de la identificación de la especie se hizo mediante claves morfológicas, se agruparon en conjuntos de cinco individuos teniendo en cuenta el distrito y lugar de muestreo (intradomiciliario o peridomiciliario). Se extrajo ADN, posteriormente se realizó una PCR convencional y una PCR en tiempo real (RT-PCR) para detectar la presencia de B. bacilliformis, posteriormente se confirmó mediante secuenciación. Se analizaron un total de 383 individuos de la especie L. maranonensis. Se identificó mediante secuenciación que 2 (2.6%) de los grupos de mosquitos positivos por PCR convencional y RT-PCR eran 2 B. bacilliformis, dichos grupos provinieron del distrito de Querocotillo. Además, 2 (2.6%) otros grupos positivos por PCR convencional pero negativos por RT-PCR se identificaron mediante secuenciación como Mesorhizobium spp., una protobacteria filogenéticamente cercana a B. bacilliformis. Este estudio presenta evidencia molecular de que L. maranonensis es portador de B. bacilliformis y potencial vector de la Enfermedad de Carrión en el distrito de Querocotillo del departamento de Cajamarca. Futuras investigaciones podrían determinar si L. maranonensis es un vector que podría transmitir B. bacilliformis. / Tesis

Invasive species are generally problematic where they occur, especially in terms of ecology, economy and disease. Members of the genus Rattus Fischer, 1803 particularly, are known as one of the most destructive invasive species to date since they cause widespread damage on terrestrial and island ecosystems. Two Rattus species have historically been reported as invasive species in South Africa, Rattus rattus Linnaeus, 1758, which has a widespread distribution throughout the country and Rattus norvegicus Berkenhout, 1769 which is primarily distributed along the coast of South Africa. A third species, Rattus tanezumi Temminck, 1844 (which forms part of the R. rattus species complex), a south-east Asian endemic, was first reported in 2005 to also occur in South Africa (and Africa). As this species is morphologically similar to R. rattus, its identification is reliant on molecular typing approaches. In the current study, molecular, morphological and disease aspects of South African Rattus were assessed. The nature and extent of variation between the three species was investigated using cytochrome b sequences and extensive mitochondrial d-loop database for comparative purposes. D-loop data identified one, four and two haplotypes for R. tanezumi, R. rattus and R. norvegicus, respectively whereas cytochrome b data identified additional haplotypes for R. rattus and R. tanezumi. Pairwise sequence divergence was highest between R. norvegicus and R. tanezumi (12.5% for D-loop and 12.0% for cyt b). Rattus norvegicus was recovered in the central parts of South Africa for the first time and occurred sympatrically with R. tanezumi at one locality, whereas Rattus rattus and R. tanezumi occurred sympatrically at three localities. The external and qualitative cranial morphology of all three species was compared in an attempt to find differences that could be used to morphologically differentiate between these Rattus species. Whereas R. norvegicus can easily be distinguished from R. rattus and R. tanezumi, there are no discernible morphological differences to distinguish R. rattus and R. tanezumi. A taxonomic synthesis and an identification key of the three species of Rattus based on qualitative morphology, molecular and cytogenetic data using genetically-identified individuals is provided. Members of South African Rattus were also found to be carriers of the bacteria Bartonella Strong et al., 1915 and Helicobacter Goodwin et al., 1989 emend. Vandamme et al., 1991. Bartonella elizabethae (Daly et al., 1993) Brenner et al., 1993, occurring in Rattus around the world was for the first time recovered from South African Rattus. This bacterium has been associated with infective endocarditis in humans and may pose a threat to immuno-compromised individuals in rural South African communities where Rattus occurs commensally. Two Helicobacter species, H. rodentium Shen et al., 1997 and H. muridarum Lee et al., 1992, were identified neither of which have known zoonotic potential. Apart from contributing to general small mammal studies in Africa, the present study may have implications in epidemiological, agricultural, biological conservation, and invasion biology research associated with problem rodents in the southern African subregion and beyond. / Dissertation (MSc)--University of Pretoria, 2010. / Zoology and Entomology / unrestricted

This thesis focuses on the genomic study of symbionts of two different groups of hymenopterans: bees and ants. Both groups of insects have major ecological impact, and investigating their microbiomes increases our understanding of their health, diversity and evolution. The study of the bee gut microbiome, including members of Lactobacillus and Bifidobacterium, revealed genomic processes related to the adaptation to the gut environment, such as the expansion of genes for carbohydrate metabolism and the acquisition of genes for interaction with the host. A broader genomic study of these genera demonstrated that some lineages evolve under strong and opposite substitution biases, leading to extreme GC content values. A comparison of codon usage patterns in these groups revealed ongoing shifts of optimal codons. In a separate study we analysed the genomes of several strains of Lactobacillus kunkeei, which inhabits the honey stomach of bees but is not found in their gut. We observed signatures of genome reduction and suggested candidate genes for host-interaction processes. We discovered a novel type of genome architecture where genes for metabolic functions are located in one half of the genome, whereas genes for information processes are located in the other half. This genome organization was also found in other Lactobacillus species, indicating that it was an ancestral feature that has since been retained. We suggest mechanisms and selective forces that may cause the observed organization, and describe processes leading to its loss in several lineages independently. We also studied the genome of a species of Rhizobiales bacteria found in ants. We discuss its metabolic capabilities and suggest scenarios for how it may affect the ants’ lifestyle. This genome contained a region with homology to the Bartonella gene transfer agent (GTA), which is a domesticated bacteriophage used to transfer bacterial DNA between cells. We propose that its unique behaviour as a specialist GTA, preferentially transferring host-interaction factors, originated from a generalist GTA that transferred random segments of chromosomal DNA. These bioinformatic analyses of previously uncharacterized bacterial lineages have increased our understanding of their physiology and evolution and provided answers to old and new questions in fundamental microbiology.

The main aim of the current study was to determine the prevalence and diversity of potentially zoonotic bacterial genera in accurately identified indigenous rodents from South Africa. Bacterial prevalence and diversity were determined by PCR amplification and sequence analyses. Rodents were molecularly identified by amplification and sequence analysis of the mitochondrial cytochrome b gene region. Three species (Aethomys ineptus, Mastomys coucha and Otomys angoniensis) belonging to murid species complexes were identified. Furthermore, phylogenetic analyses revealed that both the proposed subspecies (R. dilectus dilectus and R. d. chakae) within the recently erected Rhabdomys dilectus occur in Hammanskraal and at the University of Pretoria Experimental farm, both in the Gauteng Province of South Africa. An overall bacterial prevalence of 38.6 % was observed in kidney samples of commensal and natural indigenous rodents after molecular screening with broad range 16S rRNA gene primers. Nucleotide sequence analyses identified a diverse range of bacterial genera namely, Bartonella, Anaplasma, Helicobacter, Burkholderia, Streptococcus, Aerococcus and Lactobacillus. Some members of these genera have been identified as causative agents of human and animal diseases, being transmitted either through environmental contamination or through haematophagous arthropod vectors. Subsequent genus-specific bacterial screening focussed on vector-borne genera identified in the commensal and natural rodent populations sampled. Bartonella prevalence and genetic diversity was compared between a natural and commensal population of the southern multimammate mouse (M. coucha) using two gene regions (Citrate synthase gene and NADH dehydrogenase gamma subunit gene). A significantly higher infection prevalence was detected in the commensal population (92.9 %) as compared to the natural population (56.9 %). No differences however, were detected between infection status and the ectoparasite loads calculated for both rodent populations. Apart from several novel Bartonella strains identified in both M. coucha populations, phylogenetic analyses also identified a species of known zoonotic potential (B. elizabethae) in both populations. The present study represents one of the first to screen indigenous rodents for tick-borne members of the bacterial family Anaplasmataceae. Anaplasma bovis-like DNA was detected in five of the six rodent species sampled (A. ineptus, Lemniscomys rosalia, M. coucha, O. angoniensis and R. dilectus) at an overall prevalence of 39.2 %. The potentially zoonotic Ehrlichia ewingii was detected in M. coucha samples only at a prevalence of 5.3 %. The diverse bacterial genera detected in commensal and natural populations of indigenous rodents comprise members of zoonotic potential and agricultural significance, highlighting the importance of continuous disease surveillance of indigenous rodents. / Dissertation (MSc)--University of Pretoria, 2014. / National Research Foundation (NRF) / Zoology and Entomology / MSc / Unrestricted

Bed bugs (Hemiptera:Cimicidae) are a common, hematophagous ectoparasite of humans and other animals, and are experiencing an international resurgence. Cimicids have been implicated in the transmission many disease agents, including various Bartonella species, however disease transmission has not yet been confirmed. Bartonella spp. are transmitted by a variety of arthropods, including fleas, lice and sand flies, and it is speculated that bed bugs may also serve as a potential vector. In this study, we used an artificial membrane to feed two groups of adult Cimex lectularius rabbit blood, either infected or uninfected with Bartonella henselae. After two weeks, the presence of Bartonella henselae was assessed via PCR, and salivary glands from infected and uninfected bed bugs were dissected and processed for transmission electron microscopy. We were unable to visually identify Bartonella henselae in the images, and therefore unable to confirm the role of bed bugs in B. henselae transmission.