C.L. Obi

Inhibitory properties of selected South African medicinal plants against Mycobacterium tuberculosis.

ETHNOPHARMACOLOGICAL RELEVANCE Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB) is the most commonly notified disease and the fifth largest cause of mortality. One in 10 cases is resistant to treatment in some areas. Several plants are used locally to treat TB-related disease. AIMS OF THE STUDY The aim was to screen selected South African medicinal plants used to treat TB and related symptoms by traditional healers for antimycobacterial activity. MATERIALS AND METHODS Ethnobotanical information on these plants was obtained. Crude acetone, methanol, hexane and ethanol extracts of 21 selected medicinal plants obtained in Venda, South Africa were screened for their ability to inhibit MTB H(37)Ra and a clinical strain resistant to first-line drugs and one second-line drug using tetrazolium microplate assay to determine the minimum inhibitory concentration (MIC). Results were analyzed using Microsoft Excel 2007 and One way ANOVA; p<0.05 was considered for statistical significance. RESULTS Few acetone extracts were active against MTB with MIC under 100 microg/mL. Four plants showed lower MIC values; Berchemia discolor Klotzsch Hemsl 12, 5 microg/mL on H(37)Ra and 10.5 microg/mL on the clinical isolate, Bridelia micrantha Hochst. Baill (25 microg/mL), Warbugia salutaris Bertol. F Chiov (25 microg/mL), and Terminalia sericea Burch ex D. F (25 microg/mL) on both H(37)Ra and clinical isolate. However, the roots of Ximenia caffra Sond. Var. caffra, barks of Sclerocarya birrea (A Rich) Hochst, Asclepias fruticosa L, tubers of Allium sativum L, leaves of Carica papaya L, Solanum panduriforme E. Mey C, and roots of Securidaca longepedunculata Fresen gave MIC greater than 100 microg/mL. CONCLUSION The acetone extracts of Berchemiadiscolor, Bridelia micrantha, Terminalia sericea and Warbugia salutaris could be important sources of mycobactericidal compounds against multidrug-resistant MTB.

Evaluation of the antibacterial and anticancer activities of some South African medicinal plants

BackgroundSeveral herbs are traditionally used in the treatment of a variety of ailments particularly in the rural areas of South Africa where herbal medicine is mainly the source of health care system. Many of these herbs have not been assessed for safety or toxicity to tissue or organs of the mammalian recipients.MethodsThis study evaluated the cytotoxicity of some medicinal plants used, inter alia, in the treatment of diarrhoea, and stomach disorders. Six selected medicinal plants were assessed for their antibacterial activities against ampicillin-resistant and kanamycin-resistant strains of Escherichia coli by the broth micro-dilution methods. The cytotoxicities of methanol extracts and fractions of the six selected plants were determined using a modified tetrazolium-based colorimetric assay (3-(4, 5-dimethylthiazol)-2, 5-diphenyl tetrazolium bromide (MTT) assay).ResultsThe average minimum inhibitory concentration (MIC) values of the plants extracts ranged from 0.027 mg/mℓ to 2.5 mg/mℓ after 24 h of incubation. Eucomis autumnalis and Cyathula uncinulata had the most significant biological activity with the least MIC values. The in vitro cytotoxicity assay on human hepatocarcinoma cell line (Huh-7) revealed that the methanol extract of E. autumnalis had the strongest cytotoxicity with IC50 of 7.8 μg/mℓ. Ethyl acetate and butanol fractions of C. uncinulata, Hypoxis latifolia, E. autumnalis and Lantana camara had lower cytotoxic effects on the cancer cell lines tested with IC50 values ranging from 24.8 to 44.1 μg/mℓ; while all the fractions of Aloe arborescens and A. striatula had insignificant or no cytotoxic effects after 72 h of treatment.ConclusionsOur results indicate that the methanol fraction of E. autumnalis had a profound cytotoxic effect even though it possessed very significant antibacterial activity. This puts a query on its safety and hence a call for caution in its usage, thus a product being natural is not tantamount to being entirely safe. However, the antibacterial activities and non-cytotoxic effects of A. arborescens and A. striatula validates their continuous usage in ethnomedicine.

A survey of indigenous herbal diarrhoeal remedies of O.R. Tambo district, Eastern Cape Province, South Africa.

Indigenous health system and the use of herbal plants have been recognized as pivotal in primary health care and a system to reckon with in achieving one of the targets of the millennial goals on health. An ethnobotanical survey was conducted to identify indigenous herbal remedies for diarrhoea and associated stomach ailments in rural areas of the O.R. Tambo district municipality in the Eastern Cape province of South Africa. The main objective of the study was to gather ethnomedical data on potentially valuable indigenous medicinal plants for the eventual development of new pharmaceuticals and also emphasize the role of ethnomedicine in primary health care. The use of herbal remedies in the treatment of diarrhoea and dysentery was investigated using interviews. The survey was conducted among traditional healers and knowledgeable local elders who use medicinal plants to treat common illnesses. Data from the survey indicated the names of plants commonly used in the treatment of diarrhoea and associated ailments, the methods of preparation, parts used and administration. A total of 32 plant species belonging to 26 families were reportedly used as diarrhoea remedy in the study area. The most predominant families of medicinal plants employed and most frequently recommended were Fabaceae (16.67%), followed by Hyacinthaceae and Hydnoraceae (8.33% each). The most commonly utilized portions of plants for medicinal purposes included roots and leaves. Other parts were corms, bulbs, tubers, fruits and bark. The methods of preparation often employed were decoctions and infusions whilst medication was frequently administered orally or as enema. Some of the plants were used singly or mixed with other plant(s) while some edible ones are consumed as food. The survey documented a diversity of plants employed as remedy for diarrhoea. Integration of this form of health care system into western medicine is warranted. The propagation of such medicinal plants is vital for sustainable use of these medicinal plants.

Molecular basis of virulence in clinical isolates of Escherichia coli and Salmonella species from a tertiary hospital in the Eastern Cape, South Africa

BackgroundApart from localized gastrointestinal infections, Escherichia coli and Salmonella species are major causes of systemic disease in both humans and animals. Salmonella spp. cause invasive infections such as enteric fever, septicemia, osteomyelitis and meningitis while certain types of E. coli can cause systemic infections, includingpyelonephritis, meningitis and septicemia. These characteristic requires the involvement of a myriad of virulence factors.MethodsThis study investigated the virulence factors of Escherichia coli and Salmonella species in clinical specimens from patients with diarrhoea presenting to health care centres in Oliver R. Tambo District Municipality, Eastern Cape Province, Republic of South Africa. Microbiology analysis involved the use of cultural and molecular techniques.ResultsOut of a total of 315 samples screened, Salmonella isolates were obtained in 119 (37.8%) of cases and these comprised: S. choleraesuis (6%), S. enteritidis (4%), S. eppendorf (1%), S. hadar (1%), S. isangi (8%), S. panama (1%), S. typhi (52%), S. typhimurium (25%) and untyped Salmonella spp. (2%). Among the Salmonella species 87 (73.1%) were invasive. Using molecular diagnostic methods, diarrheagenic E. coli were detected in 90 cases (28.6%): the greater proportion of this were enteroaggregative E. coli (EAEC) 37 (41.1%), enteropathogenic E. coli (EPEC) 21 (23.3%) and enterohemorrhagic E. coli (EHEC) 21 (23.3%). The predominant virulence gene among the diarrheagenic E. coli was EAEC heat-stable enterotoxin astA genes while the virulence genes identified in the Salmonella strains were 15 (12.6%) flic and 105 (88.2%) inv genes. The amino acid identity of the representative genes showed 95-100% similarity to corresponding blast searched sequence.ConclusionsThis study showed the diversity of virulence gene expression in two major enteric pathogens. S. typhi and enteroaggregative E. coli were the predominant enteropathogens in our study area with an indication that EAEC is endemic within our study population. It was observed among other things that some diarrheagenic E. coli isolated from apparently asymptomatic subjects expressed some virulence genes at frequency as high as seen in diarrheagenic cases. This study underlines the importance of understanding the virulence composition and diversity of pathogens for enhanced clinico-epidemiological monitoring and health care delivery.

In-vitro cytotoxicity and antimicrobial activities, against clinical isolates of Campylobacter species and Entamoeba histolytica, of local medicinal plants from the Venda region, in South Africa

Abstract In the quest for alternative treatments against Campylobacter jejuni and Entamoeba histolytica, which are both aetiological agents of diarrhoea world-wide, the in-vitro activities against the two pathogens of extracts of 18 South African medicinal plants have recently been assessed. Forty extracts from the 18 plant species were prepared and tested against 110 clinical isolates of Campylobacter spp. In addition, extracts from eight of the plant species were tested against a standard strain (HM-1:IMSS) of E. histolytica, and the cytotoxicity of each of 19 extracts from 15 of the plant species was explored using Vero cell cultures and microdilution assays. At least one extract of each plant species investigated was found to be active against some of the Campylobacter isolates. Extracts of Lippia javanica and Pterocarpus angolensis had the highest antibacterial activity, each giving a minimum inhibitory concentration (MIC) of 90 μg/ml. Of the extracts tested against E. histolytica, however, only those of P. angolensis and Syzigium cordatum were found to have anti-amoebic activity, with MIC of 1.2 and 7.5 mg/ml, respectively. Although most of the extracts showed little toxicity against Vero cells, with most of the median inhibitory concentrations (IC50) recorded exceeding 400 μg/ml, an extract of Bauhinia galpini was quite toxic, with an IC50 of just 2.7 μg/ml. Acetone and methanol extracts of several of the plants show promise as templates for the design of new anti-diarrhoeal therapies.

Seasonal abundance and distribution of Vibrio species in the treated effluent of wastewater treatment facilities in suburban and urban communities of Eastern Cape Province, South Africa

We assessed the seasonal abundance and distribution of Vibrio species as well as some selected environmental parameters in the treated effluents of two wastewater treatment plants (WWTP), one each located in a suburban and urban community of Eastern Cape Province, South Africa. Vibrio population density ranged from 2.1×105 to 4.36×104 CFU/ml in the suburban community and from 2.80×105 to 1.80×105 CFU/ml in the urban community. Vibrio species associated with 180 μ, 60 μ, and 20 μ plankton sizes were observed at densities of 0–136×103 CFU/ml, 0–8.40×102 CFU/ml, and 0–6.80×102 CFU/ml, respectively at the suburban community’s WWTP. In the urban community, observed densities of culturable Vibrio were 0–2.80×102 CFU/ml (180 μ), 0–6.60×102 CFU/ml (60 μm), and 0–1.80× 103 CFU/ml (20 μm). The abundance of free-living Vibrio species ranged from 0 to 1.0×102 and 1.0×103 CFU/ml in the suburban and urban communities’ WWTPs, respectively. Molecular confirmation of the presumptive Vibrio isolates revealed the presence of V. fluvialis (41.38%), V. vulnificus (34.48%), and V. parahaemolyticus (24.14%) in the suburban community effluents. In the urban community molecular confirmation revealed that the same species were present at slightly different percentages, V. fluvialis (40%), V. vulnificus (36%), and V. parahaemolyticus (24%). There was no significant correlation between Vibrio abundance and season, either as free-living or plankton-associated entities, but Vibrio species abundance was positively correlated with temperature (r=0.565; p<0.01), salinity, and dissolved oxygen (p<0.05). Turbidity and pH showed significant seasonal variation (p<0.05) across the seasons in both locations. This study underscores the potential of WWTPs to be sources of Vibrio pathogens in the watershed of suburban and urban communities in South Africa.

Prevalence, antimicrobial resistance profiles of Listeria monocytognes from various foods in Gaborone, Botswana.

Listeria monocytogenes is known to cause epidemic and sporadic cases of listeriosis. The present study investigated the occurrence, antibiograms and molecular serotypes of the organism in various retail outlets in Gaborone, Botswana. Food samples were obtained randomly from selected supermarkets and street vendors in 5 geographical areas of Gaborone from May, 2007 to September 2007. L. monocytogenes was isolated and positively identified by using morphological and biochemical tests. From a total of 1324 food samples tested 57(4.3 %) were positive for L. monocytogenes. Out of the 57 isolates of L. monocytogenes 7 (12.3%), 3 (5.3%), 0 (0%), 27 (47.4%) and 20 (35.1%) were isolated from cheese, raw milk, meat (biltong), frozen cabbage and salad (coleslaw), respectively. From the 5 geographical areas selected for sampling in this study, Gaborone South recorded the highest number 19 (33.3%) of L. monocytogenes isolates while Gaborone West recorded the least, 7 (12.3%). The findings in this study reveal the presence of L. monocytogenes serotypes 1/2a and 1/2b in ready to eat food and highlight the need for education and training programmes in food safety in Gaborone, Botswana.

Molecular Characterization and Serotyping of Listeria monocytogenes with a Focus on Food Safety and Disease Prevention

I.C. Morobe1,2,4, C.L. Obi1,3, M.A. Nyila2, M.I. Matsheka4 and B.A. Gashe4 1Walter Sisulu University, Nelson Mandela Drive, Mthatha, Eastern Cape, 2School of Agriculture and Life Sciences, Department of Life and Consumer Sciences, University of South Africa, Pretoria, 3Division of Academic Affairs and Research, Walter Sisulu University, Eastern Cape, 4Department of Biological Sciences, University of Botswana, Gaborone, 1,2,3South Africa 4Botswana

Prevalence and temporal distribution of Schistosoma haematobium infections in the Vhembe district, Limpopo Province, South Africa.

Although the delayed-type hypersensitivity (DTH) skin reaction to tuberculin is used worldwide for tuberculosis (TB) detection, it has poor diagnostic specificity due to the presence of common antigens in tuberculin shared by many mycobacterial species. The problem is noticed, especially in countries where the Bacillus Calmette-Gue´rin (BCG) vaccination is widely practiced. Thus, a new skin test antigen specific for the diagnosis of Mycobacterium tuberculosis (MTB) infection is urgently needed. CFP-10, a mycobacterial secretary protein that is absent in Mycobacterium bovis BCG and most other mycobacterial species including Mycobacterium avium, Mycobacterium intracellulare, has been shown to elicit cellular immune responses in MTB infected individuals and can be a good candidate for MTB specific diagnosis. We prepared recombinant MTB CFP-10, rCFP-10, and its utility as specific antigen for TB diagnosis was evaluated by skin testing in guinea pigs sensitized with M . tuberculosis, M. bovis, and M. bovis BCG. Our results show that the purified MTB rCFP-10 antigen elicits a positive skin response only in the guinea pigs sensitized with M. tuberculosis and M. bovis , and not in the animals sensitized with M. bovis BCG vaccine. The data presented in this study supports further testing of the use rCFP-10 as the specific antigen in the skin test for the diagnosis of MTB infection in humans. Key words : Recombinant CFP-10 protein, skin test, delayed-type hypersensitivity, tuberculosis infection, Mycobacterium tuberculosis, Mycobacterium bovis, Bacillus Calmette-Gue´rin.

Uropathogens isolated from HIV-infected patients from Limpopo Province, South Africa

The primary aim of this study was to determine the prevalence and antibiotic susceptibility profiles of uropathogens isolated from HIV-infected patients in Limpopo Province, South Africa. One hundred and ninety-five urine samples were obtained from HIV-infected patients between June 2008 and May 2009 and the samples were investigated using standard and conventional microbiological methods. Urinary tract infections (UTIs) were detected in 95 samples. Enterobacter species (37.6%) was the most prevalent uropathogen. Other bacterial isolates included Escherichia coli and Klebsiella species, each constituting 17.9%, Citrobacter species (9.7%), Proteus species (7.4%) and others (11.6%). Resistance to trimethoprim/sulfamethoxazole (SXT) which is used for empiric therapy was above 35%. However, majority of the isolates were susceptible to amikacin, ciprofloxacin and most of the second generation cephalosporins as well as imipenem. Resistance of uropathogens to SXT in Limpopo Province is higher than the recommended IDSA setting and this requires the introduction of an alternative first-line therapy. Keywords: Antibiotic resistance, HIV, uropathogens, urinary tract infections