Pathogen In South Africa Research Articles

Trends and pattern of antimicrobial resistance among blood culture isolates of selected bacterial pathogens in South Africa, 2005-2009

Trends and pattern of antimicrobial resistance among blood culture isolates of selected bacterial pathogens in South Africa, 2005-2009

National surveillance of private sector respiratory tract pathogens in South Africa, 2010

Antibiotics are prescribed more frequently for community-acquired respiratory tract infections than any other infection. However, antibiotic resistance is an increasing problem worldwide. When selecting an antimicrobial agent for empirical therapy, it is important to know the susceptibility patterns of the bacteria that frequently cause these infections in a particular geographical region.

Temporal spore dispersal patterns of grapevine trunk pathogens in South Africa

Trunk disease pathogens of grapevines, viz. Phaeomoniella chlamydospora, Eutypa lata and several species in Botryosphaeriaceae, Phaeoacremonium and Phomopsis are known to infect fresh pruning wounds by means of air-borne inoculum released after rainfall or prolonged periods of high relative humidity. Recent surveys have demonstrated that most or all of these pathogens are present in climatically diverse grape growing regions of South Africa. However, the factors controlling spore dispersal of these pathogens in vineyards were largely unknown. To address this question, spore trapping was done in a Chenin Blanc vineyard in the Stellenbosch area, South Africa, for 14 weeks during the grapevine pruning period from June to mid-September of 2004 and 2005. Hourly recordings of weather data were done by a weather station in the row adjacent to the spore trap. Spores of E. lata and Phomopsis and species in Botryosphaeriaceae were trapped throughout the trapping periods of 2004 and 2005, with higher levels of trapped spores recorded in 2005. The spores of all three pathogens were trapped during or after periods of rainfall and/or high relative humidity. In neither of the 2 years were spores of Pa. chlamydospora or Phaeoacremonium spp. trapped. Results indicated that spore event incidence, as well as the amount of spores released during a spore event of above-mentioned pathogens, were governed by rainfall, relative humidity, temperature and wind speed prior to and during the spore events.

RESOLVING THE STATUS OF MONILINIA spp. IN SOUTH AFRICAN STONE FRUIT ORCHARDS

Geographical distribution records of pathogens and pests are the basis for phytosanitary decision-making. Monilinia fructicola, one of the three Monilinia species responsible for brown rot of stone fruit, is listed as a regulated pest for South Africa. Many disputes about the justification of this classification have arisen during the past years as records have been published regarding the presence of this pathogen in South Africa. Results of several surveys conducted from 1985 in stone fruit orchards, revealed that M. laxa is the only causal agent of brown rot in South Africa. However, another notification of non-compliance (interception of regulated pests) was received by the National Plant Protection Organisation of South Africa in 2003 stating that M. fructicola was detected on consignments of South African Prunus fruits (P. domestica) in the United Kingdom. A detection survey according to inspections and sampling relevant to the biology of Monilinia species were conducted in the identified orchards at various stages throughout the year. Molecular techniques with species-specific primers for M. fructicola, M. laxa and M. fructigena based on the EPPO Diagnostic Protocol for M. fructicola were used for the identification of presumptive positive Monilinia isolates. The absence of M. fructicola from South African stone fruit orchards was again confirmed by this survey and its status in South Africa can be reported as: absent, not known to occur, confirmed by a detection survey. The regulated status of M. fructicola in South Africa is therefore scientifically justified by the results from this survey.

Genetic diversity in theEucalyptusstem pathogenTeratosphaeria zuluensis

Coniothyrium canker caused by the fungal pathogen Teratosphaeria (= Coniothyrium) zuluensis is one of the most important diseases affecting plantation-grown Eucalyptus trees. Little is known regarding the pathogen and this study consequently considers the genetic diversity and population structure of T. zuluensis. Eleven microsatellites markers, of which six were developed in this study, were used to analyse two temporally separated populations of T. zuluensis from South Africa, one population from Malawi and one population from China. Results showed that the populations of T. zuluensis have a moderate to high diversity and that clonal reproduction is predominant. There was also evidence that the genetic diversity of the pathogen in South Africa has increased over time. Comparison of T. zuluensis populations from South Africa, Malawi and China suggest that South Africa is most probably not the centre of origin of the pathogen as has previously been suggested.

Phytophthora capsicion vegetable hosts in South Africa: distribution, host range and genetic diversity

The oomycete Phytophthora capsici is an economically important plant pathogen worldwide. Not much is known about this pathogen in South Africa. Therefore, the first aim of the study was to obtain a better understanding of the host range and distribution of the pathogen. Second, South African P. capsici isolates were characterised through mating-type tests and genotyping with eight microsatellite markers (simple sequence repeat markers (SSR)) that were developed from the draft genome sequence. Analyses of diseased samples from 2000 to 2008 showed that P. capsici was present in at least five provinces on cucurbitaceous (Cucumis melo and Cucurbita spp.) and solanaceous (Capsicum spp. and Lycopersicon esculentum) crops. Mating-type analyses of 78 isolates collected from these hosts showed that both mating types were present in all the sampled production regions. The mating-type frequency in the total South African population did not deviate significantly from a 1: 1 ratio. Microsatellite genotyping of the isolates revealed that genotypic diversity was high in all regional populations with 59 of 78 isolates representing unique SSR multilocus genotypes (MLG). The remaining 19 isolates consisted of eight MLG that each included two to three isolates with identical SSR alleles. These identical isolates were considered to be clones that were derived from asexual reproduction due to significant Psex <0.003 and Psex( f ) <0.008 probability values. Clonal genotypes were identified within and between production regions (Limpopo and Mpumalanga), on different crops (bell pepper, piquante pepper and tomato) and across years.

Trends in udder health and emerging mastitogenic pathogens in South African dairy herds

The aim of this study was to retrospectively analyse the results of milk samples obtained from South African dairy herds during the period 1996 to April 2007 in order to identify possible trends in isolates of microorganisms and their pathogenicity under field conditions. Milk samples were obtained from 7 of the 9 provinces in South Africa where there are low numbers of dairy cows. Although there is scientific limitation to a country wide survey, such as the variation in herd size, management skills, parity, milk yield, milking frequency and other parameters, the size of this database helps to give a fair indication of general udder health in South Africa. Cytology and routine bacteriology were performed on 379,000 milk samples of lactating cows and bacteriology on 11,946 samples from non-lactating cows. According to the results obtained, mastitis did not decrease in South Africa over the test period. The prevalence of mastitis and teat canal infection was lowest in 2002. Mastitis and teat canal infection increased from 2002 to 2006 from 8.1% and 24.1% to 15.4 and 30.0% respectively. The percentage of mastitogenic pathogens isolated from cows over these years also varied. Previously unknown or almost eradicated mastitogenic pathogens such as alphabeta haemolytic Staphylococcus aureus which is thought to be of human origin, Streptococcus agalactiae and Enterococcus canis were responsible for numerous mastitis outbreaks seen in the test samples. Coagulase-negative staphylococci were the most frequently isolated bacteria in milk samples from both lactating and dry cows, followed by Staphylococcus aureus and Streptococcus agalactiae. Although Staphylococcus aureus remained the principal mastitogenic pathogen in South Africa, owing to its chronic nature and resultant economic losses, most cases of mastitis were caused by coagulase-negative staphylococci. This finding increases the importance of coagulase-negative staphylococci (formerly described as a minor pathogen) significantly. Isolations of Streptococcus agalactiae peaked between 2000 and 2005 and decreased again by 2007. Coagulase-negative staphylococcal isolates increased from 2002 and were still on the increase in 2007. Streptococcus agalactiae, Streptococcus uberis and Enterococcus canis were isolated more frequently from milk samples of lactating cows compared with dry cows, while Enterococcus faecalis was isolated more frequently from dry cow samples.

Improving injection safety.

Inadequate infection prevention and control (IPC) practices have highlighted concerns about the medical transmission of blood-borne and air-borne pathogens in South Africa. The National Department of Health (NDOH) and its partners have renewed efforts to minimise the risk of health care-associated transmissions. The success of this endeavour depends on the involvement and dedication of doctors, nurses and all those who handle health risk waste.

Phylogeny of the Quambalariaceae fam. nov., including important Eucalyptus pathogens in South Africa and Australia

The genus Quambalaria consists of plant-pathogenic fungi causing disease on leaves and shoots of species of Eucalyptus and its close relative, Corymbia. The phylogenetic relationship of Quambalaria spp., previously classified in genera such as Sporothrix and Ramularia, has never been addressed. It has, however, been suggested that they belong to the basidiomycete orders Exobasidiales or Ustilaginales. The aim of this study was thus to consider the ordinal relationships of Q. eucalypti and Q. pitereka using ribosomal LSU sequences. Sequence data from the ITS nrDNA were used to determine the phylogenetic relationship of the two Quambalaria species together with Fugomyces (= Cerinosterus) cyanescens. In addition to sequence data, the ultrastructure of the septal pores of the species in question was compared. From the LSU sequence data it was concluded that Quambalaria spp. and F. cyanescens form a monophyletic clade in the Microstromatales, an order of the Ustilaginomycetes. Sequences from the ITS region confirmed that Q. pitereka and Q. eucalypti are distinct species. The ex-type isolate of F. cyanescens, together with another isolate from Eucalyptus in Australia, constitute a third species of Quambalaria, Q. cyanescens (de Hoog & G.A. de Vries) Z.W. de Beer, Begerow & R. Bauer comb. nov. Transmission electron-microscopic studies of the septal pores confirm that all three Quambalaria spp. have dolipores with swollen lips, which differ from other members of the Microstromatales (i.e. the Microstromataceae and Volvocisporiaceae) that have simple pores with more or less rounded pore lips. Based on their unique ultrastructural features and the monophyly of the three Quambalaria spp. in the Microstromatales, a new family, Quambalariaceae Z.W. de Beer, Begerow & R. Bauer fam. nov., is described.

First Report of Pink Disease on Native Trees in South Africa and Phylogenetic Placement of Erythricium salmonicolor in the Homobasidiomycetes.

Erythricium salmonicolor causes a canker and die-back disease, commonly known as pink disease, on many tree species. During an investigation of diseases of Podocarpus henkellii and P. latifolius in the Mpumalanga Province of South Africa, typical symptoms of pink disease were observed on the branches of these trees. Stem and branch cankers covered with cracked bark and abundant pink mycelial growth were common on the affected trees. In subsequent surveys, the disease was also found on native Dais cotonifolia in the same area, as well as on native Ekebergia capensis and Maesa lanceolata in the KwaZulu-Natal Midlands. Phylogenetic analyses of ribosomal large subunit DNA sequence data were used to confirm the identity of the pathogen and obtain an indication of its phylogenetic placement within the Homobasidiomycetes. Isolates from all the native hosts recorded in this study, as well as from exotic Eucalyptus sp. and Acacia mearnsii, formed a strongly supported clade together with isolates from other parts of the world. Results confirmed that the pathogen in South Africa is Erythricium salmonicolor. Isolates from South Africa and Ethiopia grouped closely together, slightly different from E. salmonicolor isolates from the rest of the world. Our data also suggest that the genus name for E. salmonicolor possibly should be reconsidered because it groups separately from E. laetum or Corticium roseum. Phylogenetic analyses further indicated that the genus Erythricium is most closely related to Marchandiomyces aurantiacus, M. lignicola, C. roseum, E. laetum, Dendrothele maculata, D. roseacarneum, Vuilleminia comedens, V. macrospora, Punctularia strigoso-zonata and Galzinia incrustans. These genera form a separate subclade, the corticioid clade, within the Homobasidiomycetes. Pink disease is potentially important in South Africa because it affects a wide range of native and exotic tree species, and this study provides a foundation for further research.

National surveillance programme on susceptibility patterns of respiratory pathogens in South Africa: moxifloxacin compared with eight other antimicrobial agents

Aims: The susceptibility patterns of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Klebsiella pneumoniae, and Streptococcus pyogenes isolated from specimens submitted to 12 private laboratories in South Africa were determined. Methods:...

Mitochondrial DNA Relationships in an Emergent Pest of Honey Bees: &lt;I&gt;Aethina tumida&lt;/I&gt; (Coleoptera: Nitidulidae) from the United States and Africa

The hive beetle Aethina tumida Murray is a new pest of honey bee colonies in North America. Specimens of A. tumida were collected throughout its current range in the southeastern United States, and from several sites in South Africa. A 1018-bp section of the mitochondrial cytochrome c oxidase I gene was amplified and sequenced in 26 beetles collected from Florida, Georgia, South Carolina, and North Carolina, and in 14 beetles collected from seven sites in South Africa. Mitochondrial DNA variation between all A. tumida samples was <0.8%, which was still considered within the range expected for a single species. The U.S. samples showed two distinct haplotypes, differing by 6 bp (0.6%). Both haplotypes were found across and within several geographic regions, a result consistent with a single introduction into the United States. However, a broad survey of 151 beetles from their new range revealed significant heterogeneity in haplotype frequencies, perhaps resulting from multiple introductions. Although the data do not allow a precise estimate of the point from which A. tumida were accidentally exported from Africa, the close genetic similarity between beetles from the United States and South Africa indicates that studies conducted on beetle physiology, parasites, and pathogens in South Africa will have a direct bearing on populations now found in the United States.

Detection of Virulence to Lr41 in a South African Pathotype of Puccinia recondita f. sp. tritici.

The Lr41 gene for resistance to leaf rust, caused by Puccinia recondita f. sp. tritici, was transferred from Triticum tauschii accession TA2460 to bread wheat (T. aestivum) at the Wheat Genetics Resource Center, Kansas State University (1). Due to the high degree of resistance (primary leaf infection types [ITs] 0; to ;1= [0 to 4 scale]) conferred to South African pathotypes of leaf rust, the gene was considered potentially valuable in local programs directed at wheat germ plasm improvement. During routine glasshouse tests for seedling resistance to the South African leaf rust pathotype UVPrt16, several sporulating pustules (IT 4) were observed among flecks on wheat line KS90WGRC10 (TAM107*3/TA2460). Rust cultures multiplied from these pustules were tested on seedlings of 31 wheat lines with different Lr genes in a growth cabinet at 20°C. Their avirulence/virulence characteristics suggested a single-step mutation for virulence to Lr41. According to North American nomenclature (2), the Lr41-virulent isolate is classified as race FDC-14b,20,23,25,33,41. Low ITs were recorded on additional testers with Lr3bg, 14a, 15, 18, 19, 27+31, 28, and 29, and intermediate ITs on lines with Lr2b, 10, 21, 32, and 36. Infection studies on adult plants showed that KS90WGRC10 and its recurrent parent TAM107 produced similar susceptible reactions (Its 3++C) to the mutant. T. tauschii accession TA2460, however, was moderately susceptible (IT 2+) to this culture. Virulence to Lr41 has not been recorded in field populations of the pathogen in South Africa. The occurrence of virulence to Lr41 emphasized the nondurability of monogenic resistance and thus the importance of conserving genetic diversity for leaf rust resistance. To protect Lr41 from becoming obsolete, it should be used only in combination with other effective resistance gene(s).