Polymorphisms in pfcrt, pfmdr1, dhfr genes and in vitro responses to antimalarials in Plasmodium falciparum isolates from Bangui, Central African Republic.
(25/97)
Drug resistance is probably the greatest challenge to most malaria-control programs. Given the limited resources for other malarial-control measures, rational drug used is crucial. Molecular markers for parasite resistance such as pfcrt, pfmdr-1, and dhfr have the potential to be used in an integrated fashion to provide timely information that is useful to policy makers. Therefore, we evaluated polymorphisms in these genes from Plasmodium falciparum and their association with in vitro antimalarial drug resistance to 135 parasites samples collected in Bangui in 2004. For the dhfr gene, we found a strong association between the dhfr genotype and chemosensitivity to pyrimethamine. For the pfcrt gene, we found that haplotypes with mutant-type alleles led to significant changes in the IC50 values for chloroquine, monodesethylamodiaquine, and quinine. We found no correlations for the pfmdr1 gene. These findings suggest that a regular monitoring and screening for resistance markers for antifolates and for chloroquine could act as an adjunct to in vivo trials. (+info)
Enteropathogenic Escherichia coli o157 in Bangui and N'Goila, Central African Republic: A brief report.
(26/97)
Escherichia coli O157:H7 producing Shiga like toxins is a food-borne pathogen frequently isolated in Bangui from patients with hemorrhagic colitis (HC). This survey provides comprehensive data on the high prevalence of E. coli O157:H7 infection in Bangui: carriage of E. coli O157:H7 by zebu (Bos indicus) and fish, contamination of the fields at N'Goila where the butchers kill the zebus, and contamination of the field surface water along the M'Poko River upstream of the Oubangui River where fish are caught, appear to be important contributory factors. We also describe novel strains of serogroup O157:NM isolated from zebu and from fish; a variety of assays indicate that these strains belong to the enteropathogenic pathotype, though they lack certain genetic elements thought to be diagnostic for this pathotype. (+info)
Multidrug-resistant Mycobacterium tuberculosis, Bangui, Central African Republic.
(27/97)
We investigated multidrug-resistant (MDR) Mycobacterium tuberculosis strains in Bangui, Central African Republic. We found 39.6% with the same spoligotype and synonymous single nucleotide polymorphism in the mutT1 gene. However, strains had different rpoB mutations responsible for rifampin resistance. MDR strains in Bangui may emerge preferentially from a single, MDR-prone family. (+info)
Evaluation of the diethylcarbamazine patch to evaluate onchocerciasis endemicity in Central Africa.
(28/97)
OBJECTIVE: As part of a baseline data collection for assessing the impact of the African Programme for Onchocerciasis Control, to evaluate the diethylcarbamazine (DEC) patch test in determining the endemicity of onchocerciasis. METHOD: A total of 226 untreated children aged 3-5, living in four selected endemic foci, in Cameroon, Gabon and Central African Republic, were tested. Observed graded skin reactions to the patch were analysed and compared with the prevalence of onchocercal nodules and reactive skin disease in the corresponding community. RESULTS: The proportion of children who tested positive ranged from 25.0% to 77.1%. The values were closely correlated with the prevalence of nodules, i.e. the level of endemicity for onchocerciasis. CONCLUSION: The DEC patch test, which has been so far used only in West African foci of onchocerciasis, can also constitute a valuable tool to evaluate the levels of endemicity of onchocerciasis in Central Africa, and to follow-up the intensity of transmission of Onchocerca volvulus. (+info)
Prey synchronize their vigilant behaviour with other group members.
(29/97)
It is generally assumed that an individual of a prey species can benefit from an increase in the number of its group's members by reducing its own investment in vigilance. But what behaviour should group members adopt in relation to both the risk of being preyed upon and the individual investment in vigilance? Most models assume that individuals scan independently of one another. It is generally argued that it is more profitable for each group member owing to the cost that coordination of individual scans in non-overlapping bouts of vigilance would require. We studied the relationships between both individual and collective vigilance and group size in Defassa waterbuck, Kobus ellipsiprymnus defassa, in a population living under a predation risk. Our results confirmed that the proportion of time an individual spent in vigilance decreased with group size. However, the time during which at least one individual in the group scanned the environment (collective vigilance) increased. Analyses showed that individuals neither coordinated their scanning in an asynchronous way nor scanned independently of one another. On the contrary, scanning and non-scanning bouts were synchronized between group members, producing waves of collective vigilance. We claim that these waves are triggered by allelomimetic effects i.e. they are a phenomenon produced by an individual copying its neighbour's behaviour. (+info)
Characterization of sulphonamide resistance genes and class 1 integron gene cassettes in Enterobacteriaceae, Central African Republic (CAR).
(30/97)
OBJECTIVES: The aim of this study was to characterize genes encoding sulphonamide resistance and gene cassettes associated with class 1 integrons in trimethoprim-sulphamethoxazole resistant Enterobacteriaceae recovered from Bangui, Central African Republic (CAR). METHODS: We studied 78 clinical Enterobacteriaceae isolates, including 16 extended-spectrum beta-lactamases producers, 10 Salmonella and 9 Shigella, resistant to trimethoprim-sulphamethoxazole as assessed by the disc diffusion method. PCR was used to test for sul1 and sul2 genes. Class 1 integron resistance gene cassettes were characterized by directly sequencing PCR products obtained with primers recognising 5' and 3' conserved regions. RESULTS: The sul1 gene was found in 67 isolates, the sul2 gene in 72 isolates and both genes in 62 isolates, while the int1 gene was found in 74 isolates. The most prevalent dfr genes were dfrA7 (49%), dfrA1 (17%) and dfrA2d (13%). CONCLUSION: These results illustrate the wide distribution of sulphonamide and trimethoprim resistance genes among Enterobacteriaceae in Bangui (CAR). (+info)
Molecular characterization of African orthobunyaviruses.
(31/97)
The genus Orthobunyavirus is composed of segmented, negative-sense RNA viruses that are responsible for mild to severe human diseases. To date, no molecular studies of bunyaviruses in the genus Orthobunyavirus from central Africa have been reported, and their classification relies on serological testing. Four new primer pairs for RT-PCR amplification and sequencing of the complete genomic small (S) RNA segments of 10 orthobunyaviruses isolated from the Central African Republic and pertaining to five different serogroups have been designed and evaluated. Phylogenetic analysis showed that these 10 viruses belong to the Bunyamwera serogroup. The S segment sequences differ from those of the Bunyamwera virus reference strain by 5-15 % at the nucleotide level, and both overlapping reading frames, encoding the nucleocapsid (N) and non-structural (NS) proteins, were evident in sequenced genomes. This study should improve diagnosis and surveillance of African bunyaviruses. (+info)
A non-sense mutation in the putative anti-mutator gene ada/alkA of Mycobacterium tuberculosis and M. bovis isolates suggests convergent evolution.
(32/97)
BACKGROUND: Previous studies have suggested that variations in DNA repair genes of W-Beijing strains may have led to transient mutator phenotypes which in turn may have contributed to host adaptation of this strain family. Single nucleotide polymorphism (SNP) in the DNA repair gene mutT1 was identified in MDR-prone strains from the Central African Republic. A Mycobacteriumtuberculosis H37Rv mutant inactivated in two DNA repair genes, namely ada/alkA and ogt, was shown to display a hypermutator phenotype. We then looked for polymorphisms in these genes in Central African Republic strains (CAR). RESULTS: In this study, 55 MDR and 194 non-MDR strains were analyzed. Variations in DNA repair genes ada/alkA and ogt were identified. Among them, by comparison to M. tuberculosis published sequences, we found a non-sense variation in ada/alkA gene which was also observed in M. bovis AF2122 strain. SNPs that are present in the adjacent regions to the amber variation are different in M. bovis and in M. tuberculosis strain. CONCLUSION: An Amber codon was found in the ada/alkA locus of clustered M. tuberculosis isolates and in M. bovis strain AF2122. This is likely due to convergent evolution because SNP differences between strains are incompatible with horizontal transfer of an entire gene. This suggests that such a variation may confer a selective advantage and be implicated in hypermutator phenotype expression, which in turn contributes to adaptation to environmental changes. (+info)