Association of genetic polymorphism at tumor necrosis factor-α gene promoter - 1031T/C and parasitic infections among children in Northern South Africa.

Intestinal parasitic diseases are common in developing countries including South Africa and have been documented to be the most common in children under the age of five. The present study aimed to identify any potential association that may exist between TNF-α promoter gene polymorphism and parasitic infections. A total of 199 blood samples were evaluated from children who were part of the MAL-ED study cohort. The DNA was used to investigate polymorphism in the promoter region of the TNF-α gene at position -1031T/C. The polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. The TC genotype at position -1031 was significantly higher in healthy controls children than in children who were infected with Entamoeba species (59.9% vs 29.4%, P = 0.015) and Entamoeba coli (59.1% vs 30.8%, P = 0.046), indicating that TC genotype may be protective against Entamoeba infections and Entamoeba coli infections. The CC genotype at position -1031 was more common among children with parasite and diarrhea and the results was statistically significant (P = 0.04). This study has revealed that the CC genotype may be is a risk factor for symptomatic parasitic infections while the TC genotype might be protective of Entamoeba infections among children in Dzimauli community.

A Markov model for the effects of virological failure on HIV/AIDS progression in tuberculosis co-infected patients receiving antiretroviral therapy in a rural clinic in northern South Africa.

BACKGROUND: The goal of antiretroviral therapy (ART) is to suppress viral replication to undetectable levels. These low viral load (VL) levels may not be attained in some patients, a situation representing potential virological failure during the course of treatment. OBJECTIVES: To present the results of a Markov model exploring how virological failure and active tuberculosis (TB) affect the progression of HIV in patients on ART. METHODS: A continuous-time non-homogeneous Markov model was used to model the progression of HIV/AIDS in patients on combination ART (cART). We define seven states in our model. The first five states are based on VL levels and the other two are absorbing states: death and withdrawal from the study. The effects of TB co-infection, baseline VL, lactic acidosis and treatment failure on transition intensities were assessed. RESULTS: The model shows that VL-based transition intensities do not follow a constant rate; rather, there are two different trends in HIV/AIDS progression. The first trend is an increase in the prevalence of state 1 (undetectable VL levels) in the first 0.5 years of treatment. The second trend follows thereafter and shows a slow decrease. Within the first 0.5 years of therapeutic intervention, the undetectable VL state is therefore attainable from any VL state. However, when virological failure occurs, there is an increased risk of death. Developing active TB while on cART increases the risk of viral rebound from undetectable levels to VLs between 50 and 10 000 copies/mL by ~1.03-fold. From a VL between 10 000 and 100 000 copies/mL, developing TB while on cART increases the rate of viral rebound by ~2.5-fold. However, if TB is detected and treated at enrolment, rates of viral rebound from undetectable levels are reduced. CONCLUSIONS: The model confirms that virological failure, coupled with developing active TB while on cART, increases mortality rates irrespective of patient CD4+ count status. It also suggests that while TB at the time of cART initiation does not increase the risk of viral rebound, development of active TB after cART initiation does increase this risk. These findings highlight the importance of strengthening VL monitoring, which should be performed every 2 months, especially in patients with TB, and addressing unsuppressed VLs appropriately if they are detected.

Antibiotic resistance patterns and beta-lactamase identification in Escherichia coli isolated from young children in rural Limpopo Province, South Africa: The MAL-ED cohort.

BACKGROUND: Antibiotic resistance is a growing problem worldwide. Mechanisms of resistance vary, and some can confer resistance to multiple classes of antibiotics. OBJECTIVE: To characterise the antibiotic resistance profiles of Escherichia coli isolates obtained from stool samples of young rural children exposed or unexposed to antibiotics. METHODOLOGY: The samples were collected from children aged 4 - 12 months who were participants in the Etiology, Risk Factors, and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) project at the South Africa research site. We isolated 87 E. coli samples (clones) from 65 individual participants, all of which were subjected to disc diffusion assay to determine resistance. We characterised the minimum inhibitory concentration of antibiotics in a subset of strains as well as the mechanism by which these strains were resistant to beta-lactam antibiotics. RESULTS: Our results revealed high resistance rates to co-trimoxazole (54.0%), penicillin (47.1%) and tetracycline (44.8%) in our isolates, and indicated that the beta-lactamase TEM-1 is a prevalent source of beta-lactam resistance. We also identified two isolates with the extended-spectrum beta-lactamase CTX-M-14. CONCLUSIONS: This study identified antibiotic-resistant E. coli in children with and without prior exposure to antibiotics, with some isolates showing resistance to multiple classes of antibiotics. Clinicians should bear in mind that transmission of extended-spectrum beta-lactamase-resistant E. coli exists at the community level, and that children as young as 2 years may be harbouring these resistant phenotypes.

Antibiotic resistance patterns and beta-lactamase identification in Escherichia coli isolated from young children in rural Limpopo Province, South Africa: The MAL-ED cohort

Background. Antibiotic resistance is a growing problem worldwide. Mechanisms of resistance vary, and some can confer resistance to multiple classes of antibiotics.Objective. To characterise the antibiotic resistance profiles of Escherichia coli isolates obtained from stool samples of young rural children exposed or unexposed to antibiotics. Methodology. The samples were collected from children aged 4 - 12 months who were participants in the Etiology, Risk Factors, and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) project at the South Africa research site. We isolated 87 E. coli samples (clones) from 65 individual participants, all of which were subjected to disc diffusion assay to determine resistance. We characterised the minimum inhibitory concentration of antibiotics in a subset of strains as well as the mechanism by which these strains were resistant to beta-lactam antibiotics.Results. Our results revealed high resistance rates to co-trimoxazole (54.0%), penicillin (47.1%) and tetracycline (44.8%) in our isolates, and indicated that the beta-lactamase TEM-1 is a prevalent source of beta-lactam resistance. We also identified two isolates with the extended-spectrum beta-lactamase CTX-M-14.Conclusions. This study identified antibiotic-resistant E. coli in children with and without prior exposure to antibiotics, with some isolates showing resistance to multiple classes of antibiotics. Clinicians should bear in mind that transmission of extended-spectrum beta-lactamase-resistant E. coli exists at the community level, and that children as young as 2 years may be harbouring these resistant phenotypes

Diversity and antibiograms of bacterial organisms isolated from samples of household drinking-water consumed by HIV-positive individuals in rural settings, South Africa.

Diarrhoea is a hallmark of HIV infections in developing countries, and many diarrhoea-causing agents are often transmitted through water. The objective of the study was to determine the diversity and antibiotic susceptibility profiles of bacterial organisms isolated from samples of household drinking-water consumed by HIV-infected and AIDS patients. In the present study, household water stored for use by HIV-positive patients was tested for microbial quality, and isolated bacterial organisms were analyzed for their susceptibility profiles against 25 different antibiotics. The microbial quality of water was generally poor, and about 58% of water samples (n=270) were contaminated with faecal coliforms, with counts varying from 2 colony-forming unit (CFU)/100 mL to 2.4x104 CFU/100 mL. Values of total coliform counts ranged from 17 CFU/100 mL to 7.9x105/100 mL. In total, 37 different bacterial species were isolated, and the major isolates included Acinetobacter lwoffii (7.5%), Enterobacter cloacae (7.5%), Shigella spp. (14.2%), Yersinia enterocolitica (6.7%), and Pseudomonas spp. (16.3%). No Vibrio cholerae could be isolated; however, V. fluvialis was isolated from three water samples. The isolated organisms were highly resistant to cefazolin (83.5%), cefoxitin (69.2%), ampicillin (66.4%), and cefuroxime (66.2%). Intermediate resistance was observed against gentamicin (10.6%), cefepime (13.4%), ceftriaxone (27.6%), and cefotaxime (29.9%). Levofloxacin (0.7%), ceftazidime (2.2%), meropenem (3%), and ciprofloxacin (3.7%) were the most active antibiotics against all the microorganisms, with all recording less than 5% resistance. Multiple drug resistance was very common, and 78% of the organisms were resistant to three or more antibiotics. Education on treatment of household water is advised for HIV-positive patients, and measures should be taken to improve point-of-use water treatment as immunosuppressed individuals would be more susceptible to opportunistic infections.

Drug-susceptibility patterns of Mycobacterium tuberculosis in Mpumalanga province, South Africa: possible guiding design of retreatment regimen.

Multidrug-resistant tuberculosis (MDR-TB) has been a cause of concern in both developed and developing countries. The prevalence of drug resistance in Mycobacterium tuberculosis (MTB) isolates (n=692) from Mpumalanga province was assessed. In total, 692 (64%) MTB strains from cases with pulmonary TB were tested for susceptibility against rifampicin, isoniazid, ethambutol, and streptomycin using the MGIT 960 instrument. Two hundred and nine (30.2%) strains were resistant to one or more drugs. Resistance to one drug ranged from 1.4% for ethambutol to 17.7% for rifampicin. The prevalence of MDR-TB ranged from 6.7% for three drugs to 34% for four drugs, with significant predictors being patients' age-groups of 25-54 years (p=0.0012) and >55 years (p=0.007). The result showed a high level (58.4%) of MDR-TB from cases in Mpumalanga province. To achieve a higher cure rate in this province, drug-susceptibility tests must be done for every case.

Seroprevalence of Entamoeba histolytica in the context of HIV and AIDS: the case of Vhembe district, in South Africa's Limpopo province.

In a recent study in northern South Africa, the seroprevalence of Entamoeba histolytica infection among 257 HIV-positive and 117 HIV-negative individuals was determined, using an ELISA for the detection of antibodies reacting with the parasite's galactose/-acetyl-D-galactosamine(Gal/GalNAc)-inhibitable adherence lectin. Overall, 34.0% of the 374 participants (36.1% of the females and 28.1% of the males) were found seropositive for E. histolytica. Although all age-groups were affected by the amoebic pathogen, the subjects aged 50-59 years had the highest seroprevalence (69.2%). The seroprevalence of E. histolytica was also significantly higher among the HIV-positive subjects than among the HIV-negative (42.8% v. 14.5%; chi(2)=28.65; P<0.0001). Among the HIV-positive subjects, those with fewer than 200 CD4+ cells/microl were relatively more likely to be seropositive for E. histolytica (60.3% v. 43.8%; chi(2)=4.016; P=0.045). This is the first report indicating a positive association between E. histolytica infection and HIV in South Africa. Further studies, for example to determine the occurrence of diarrhoea or liver abscess in the study area, in relation to seropositivity for E. histolytica and/or HIV, are now needed.

Prevalence of intestinal parasitic and bacterial pathogens in diarrhoeal and non-diarroeal human stools from Vhembe district, South Africa.

In the present study, a cross-sectional survey of intestinal parasitic and bacterial infections in relation to diarrhoea in Vhembe district and the antimicrobial susceptibility profiles of isolated bacterial pathogens was conducted. Stool samples were collected from 528 patients attending major public hospitals and 295 children attending two public primary schools and were analyzed by standard microbiological and parasitological techniques. Entamoeba histolytica/E. dispar (34.2%) and Cryptosporidium spp. (25.5%) were the most common parasitic causes of diarrhoea among the hospital attendees while Giardia lamblia (12.8%) was the most common cause of diarrhoea among the primary school children (p < 0.05). Schistosoma mansoni (14.4%) was more common in non-diarrhoeal samples at both hospitals (16.9%) and schools (17.6%). Campylobacter spp. (24.9%), Aeromonas spp. (20.8%), and Shigella spp. (8.5%) were the most common bacterial causes of diarrhoea among the hospital attendees while Campylobacter (12.8%) and Aeromonas spp. (12.8%) were most common in diarrhoeal samples from school children. Vibrio spp. was less common (3% in the hospitals) and were all associated with diarrhoea. Antimicrobial resistance was common among the bacterial isolates but ceftriaxone (91%) and ciprofloxacin (88.6%) showed stronger activities against all the organisms. The present study has demonstrated that E. histolytica/dispar, Cryptosporidium, Giardia, and Cyclospora are common parasitic causes of diarrhoea in Vhembe district while Campylobacter spp. and Aeromonas are the most common bacterial causes of diarrhoea in Vhembe district of South Africa.

Entamoeba histolytica: genetic diversity of African strains based on the polymorphism of the serine-rich protein gene.

The polymorphism of the serine-rich Entamoeba histolytica protein (SREHP) among isolates obtained from different geographic regions was analyzed by a nested PCR followed by restriction analysis. Thirteen different profiles were generated from 23 E. histolytica isolates from Cameroon, Zimbabwe and South Africa while 20 others were generated from 38 E. histolytica PCR positive stool samples from South Africa. One of the profiles was common to isolates from Cameroon, Zimbabwe and South Africa and constituted the most prevalent (26.1%) of all the profiles. However, profiles unique to each country were also observed amongst the samples. A non-significant difference was observed between isolates from diarrheic and non-diarrheic samples. Of interest, of the five HIV positive stool samples three had the same profile indicating the possibility that some E. histolytica strains might be more common/pathogenic in immuno-compromised individuals. The results obtained showed that African isolates of E. histolytica may possess extremely complex genetic structures independent of geographic location. This study indicates that certain profiles might be responsible for the presentation of intestinal amoebic symptoms. However, more extended studies need to be performed in order to confirm these observations.

Cryptosporidium species: preliminary descriptions of the prevalence and genotype distribution among school children and hospital patients in the Venda region, Limpopo Province, South Africa.

In the present study, the prevalence and species distribution of Cryptosporidium among school children and hospital patients in the Venda region of South Africa was determined. Real time PCR (qPCR) was used for initial screening to detect positive samples while a nested PCR followed by restriction fragment length polymorphism was used to determine the species genotype. From a total of 244 stool samples tested, 44 (18%) had Cryptosporidium with no significant difference (chi(2)=0.04; P=0.841) between samples collected from patients attending hospitals 36/197 (18%) and the samples from primary schools 8/47 (17%). The age groups most affected were those from 2 to 5 years old (28.6%) and 50 to 59 years old (50.0%). Cryptosporidium was detected in 4 (12.5%) of the 31 HIV positive individuals. Fifty-seven percent of the Cryptosporidium positive samples were diarrheic and 26 (59.1%) had elevated lactoferrin content. C. hominis (82%) was more common than C. parvum (18%). This study has demonstrated the high prevalence of Cryptosporidium infections in the Venda region and its implications in causing diarrhea and inflammation.

Scope of potential bacterial agents of diarrhoea and microbial assessment of quality of river water sources in rural Venda communities in South Africa.

The microbial quality of several, usually untreated, surface domestic water sources, used by rural communities in the Venda Region of South Africa, was assessed to gauge their fitness for human consumption and to highlight the possible impact of waterborne diseases. The water sources studied were six points on the Levubu River and the rivers Mutale, Ngwedi, Tshinane, Makonde, Mutshindudi and Mudaswali. Total and faecal coliform, heterotrophic bacteria, enterococci and coliphage counts were used as indicators/surrogates to estimate the degree of bacterial and viral contamination respectively by standard methods. The presence of potential bacterial agents of diarrhoea such as Salmonella, Shigella, Campylobacter, Plesiomonas, Aeromonas and Vibrio was also determined. Results showed that the ranges of counts with regard to all the water sources investigated were 2.9 x 10(2) - 6.3 x 10(4) CFU/100 mL for faecal coliforms, 6.0 x 10(2) - 3.7 x 10(4) CFU/100 mL for total coliforms, 1.8 x 10(2) - 1.3 x 10(6) CFU/mL for heterotrophic plate count, 1.0 x 10(1) - 3.7 x 10(4) CFU/100 mL for enterococci and 0-13 PFU/100 mL for coliphages. These values are far higher than the acceptable maximum limits prescribed for South Africa by the Dept of Water & Forestry and the Water Research Commission - 0 CFU/100 mL, 5 CFU/100 mL, 1.0 x 10(2) CFU/mL, 0 CFU/100 mL and 1 PFU/100 mL for faecal coliforms, total coliforms, heterotrophic bacteria, enterococci and coliphages respectively. Salmonella, Shigella, Vibrio cholerae, Campylobacter, Aeromonas and Plesiomonas were isolated from several of the water sources investigated. The use of these water sources for drinking and domestic purposes poses a serious threat to the health and well being of the users and calls for urgent government intervention.