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Search Results: 1 - 10 of 2290 matches for " AW Muigai "
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Genetic diversity in pigeonpea [Cajanus cajan (L.) Millsp.] Landraces as revealed by simple sequence repeat markers
S Songok, M Ferguson, AW Muigai, S Silim
African Journal of Biotechnology , 2010,
Abstract: Genetic relationships among 88 pigeonpea accessions from a presumed centre of origin and diversity, India and a presumed secondary centre of diversity in East Africa were evaluated using six microsatellite markers. Forty-seven (47) alleles were detected in the populations studied, with a mean of eight alleles per locus. Populations were defined by region (India and East Africa) and sub-populations by country in the case of East Africa and State in the case of India. Substantial differentiation among regions was evident from Roger’s modified distance and Wright’s F statistic. Greatest genetic diversity in terms of number of alleles, number of rare alleles and Nei’s unbiased estimate of gene diversity (H) was found in India as opposed to East Africa. This supports the hypothesis that India is the centre of diversity and East Africa is a secondary centre of diversity. Within East Africa, germplasm from Tanzania had the highest diversity according to Nei’s unbiased estimate of gene diversity, followed by Kenya and Uganda. Germplasm from Kenya and Tanzania were more closely related than that of Uganda according to Roger’s modified distance. Within India, results did not indicate a clear centre of diversity. Values of genetic distance indicated that genetic relationships followed geographical proximity.
Detection and Characterization of Methicillin Resistant Staphylococcus aureus from Toilet and Classroom Door Handles in Selected Secondary Schools in Nairobi County  [PDF]
Caroline Mbogori, Anne Muigai, Samuel Kariuki
Open Journal of Medical Microbiology (OJMM) , 2013, DOI: 10.4236/ojmm.2013.34037
Abstract: Background: Staphylococcus aureus is found on all surfaces especially in public areas like hospitals and schools and on frequently touched areas like toilet and classroom door handles. Methicillin resistant Staphylococcus aureus (MRSA) is a strain of Staphylococcus aureus which is resistant to methicillin. There are two types of MRSA: Community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) and hospital acquired methicillin resistant Staphylococcus aureus (HA-MRSA). MRSA in the community presents a significant reservoir that could enter into healthcare facilities and spread among patients and also a risk for immune compromised persons in the community. Methodology: The study aimed at determining the prevalence of MRSA isolated from toilet and classroom door handles as a potential source of infection to the students and the workers in selected schools in Nairobi, Kenya. The study also compared the prevalence of MRSA between boarding and non-boarding girls, boys and mixed (both girls and boys in the same school) secondary schools. Twelve secondary schools in Nairobi County were randomly selected and 306 samples from both the toilet and classroom door handles were collected using sterile swabs and transported to the laboratory. Isolation of Staphylococcus aureus was done by the use of selective media Mannitol salt agar, antibiotic susceptibility of isolates was done by disk diffusion method, and molecular detection of mecA and PVL genes were done by polymerase chain reaction (PCR). Results: The prevalence of S. aureus was 20% and 15% were MRSA positive by both Antimicrobial Susceptibility Test and PCR detection. 20% showed the presence of PVL genes, 8% showed the presence of both genes and 56% of isolates with mecA gene had PVL genes. Conclusion: The presence of MRSA in this study emphasizes the need to formulate hygiene measures to prevent possible spread of MRSA and other transmissible pathogens to students and workers in the schools.
Serotypes and Antimicrobial Susceptibility Patterns of Nasopharyngeal Pneumococci Isolated from HIV-Infected Children in Selected Pediatric Clinics in Nairobi, Kenya  [PDF]
Catherine N. Mwangi, Gunturu Revathi, Anne W. Muigai, Samuel Kariuki
Open Journal of Medical Microbiology (OJMM) , 2016, DOI: 10.4236/ojmm.2016.61007
Abstract: Background: Streptococcus pneumoniae (pneumococcus) is one of the most frequent causes of bacterial infection in children and is a leading cause of otitis, sinusitis, pneumonia, and meningitis worldwide. Nasopharyngeal colonization is a risk factor for pneumococcal disease, a leading cause of complications and death in infants. HIV-infected persons are at high risk of invasive pneumococcal disease. Method: Nasopharyngeal swabs were collected from 296 HIV infected children below five years recruited from Gertrude’s Children hospital and Nazareth Hospital Nairobi, Kenya. The nasopharyngeal swabs were processed to isolate S. pneumoniae, which were serotyped and tested for drug susceptibility. Results: The carriage prevalence of S. pneumoniae in the study was 30.4% while the isolated serotypes were (in order of decreasing frequency): 35B, 19F, 3, 13, 15A, 11A, 16F, 7C and 23A. Most of the serotypes were resistant to the commonly used antibiotics but all were susceptible to vancomycin and chloramphenicol. Conclusion: Carriage prevalence of nasopharyngeal S. pneumonia in HIV infected children was lower than that of similar prevalence studies in children. Most of the S. pneumoniae isolates were however non pneumococcal vaccine isolates.
Phylogenetics in plant biotechnology: principles, obstacles and opportunities for the resource poor
JW Ochieng, AWT Muigai, GN Ude
African Journal of Biotechnology , 2007,
Abstract: Phylogenetic inference has become routine for most studies of genetic variation among plant taxa. However, inferring phylogenies can be confounded by both biological and computational or statistical complexities, resulting in misleading evolutionary hypotheses. This is particularly critical because the “true tree” can only truly be known in exceptional circumstances. Moreover, selecting appropriate marker(s), characters, sample sizes and the appropriate reconstruction methods offers a challenge to most evolutionary geneticists. Textbooks are generic (and sometimes outdated), and in resource poor labs, they may altogether be inaccessible. In this review, we take the worker through the low-down on reconstructing a phylogeny, review the enigmatic biological and computational problems, and examine cases where cheaper markers and extremely small sample sizes can recover a reliable phylogeny.
Localizing genes using linkage disequilibrium in plants: integrating lessons from the medical genetics
JW Ochieng, AWT Muigai, GN Ude
African Journal of Biotechnology , 2007,
Abstract: Finding genes controlling quantitative traits will aid molecular breeding for crops and livestock with superior yields, growth rates, and evolutionary potential. Such genes can be located using the candidate gene approach, genome wide scans, or by within family mapping. Linkage disequilibrium (LD) or association mapping, is a candidate gene approach that relies on detecting a statistical association between the desired quantitative trait and a molecular marker allele. This approach is emerging as a leading tool for precise estimation of QTL positions, because it offers several advantages over family-based mapping: LD mapping detects associations with greater resolution, the associations detected are relevant population wide, and in plants, the use of natural populations would circumvent the need to raise large controlled crosses. However, LD approach is facing obstacles, with well over 60% of studies reporting associations in the medical genetics disapproved in subsequent tests. A large proportion of these false associations (or lack of it) result from population stratification, while the rest may be caused by other demographic and evolutionary processes that create a statistical association between a marker allele and the trait, such as bottlenecks, natural selection, hybridization and genetic drift. The problem is expected to escalate in plants, owing to the complex population structures. Regardless of the many recent methods that purport to take into account population stratification during association tests, we discuss the reasons why in plants, a priori knowledge of population structures is essential in any robust association analysis.
Analysis of Trends in Resistance to Fluoroquinolones and Extended Spectrum Beta-Lactams among Salmonella Typhi Isolates Obtained from Patients at Four Outpatient Clinics in Nairobi County, Kenya  [PDF]
Susan Mutile Kavai, Mourine Kangogo, Anne W. T. Muigai, Samuel Kariuki
Advances in Microbiology (AiM) , 2018, DOI: 10.4236/aim.2018.87038
Abstract: Typhoid fever caused by the bacterium Salmonella enterica serovar Typhi (S. Typhi) causes an estimated 25 million illnesses and approximately 200,000 deaths annually mostly in developing countries. Although the management of typhoid fever has been effectively through antibiotic treatment, S. Typhi is increasingly becoming resistant to the currently recommended drugs. This study utilized a quasi-experimental design focusing on archived samples to describe antimicrobial susceptibility patterns of S. Typhi and determine the genetic basis of resistance to the two most commonly used classes of antimicrobials. A total sample size of 287 isolates of S. Typhi isolates stored in -80°C freezer at the Centre for Microbiology Research was utilized. Isolates were subjected to anti-microbial susceptibility testing to commonly available antimicrobials using disk diffusion method, then analyzed for trends in resistance to fluoroquinolones and extended spectrum beta lactams. Among the 287 isolates 158 (55.5%) were found to be Multi Drug Resistant (MDR). This implied that these isolates were resistant to all first line classes of treatment such as ampicillin, chloramphenicol and sulfamethoxazole-trimethroprim. In addition to this, these isolates were also resistant to at least one of the currently recommended drugs of choice, either a β-lactam or a fluoroquinolone. This study observed resistances at 18.2% and 15.4% to fluoroquinolones and cephalosporins respectively. PCR results revealed presence of blaTEM, blaINT and blaCTX-M genes coding for resistance to β-lactams in 80% of the isolates that had combined resistance to β-lactams and fluoroquinolones. It is likely that recent heavy use of these classes of antimicrobials is driving resistances to these antimicrobials.
Leaf storage conditions and genomic DNA isolation efficiency in Ocimum gratissimum L. from Kenya
LG Matasyoh, FN Wachira, MG Kinyua, AWT Muigai, TK Mukiama
African Journal of Biotechnology , 2008,
Abstract: Storage of plant tissues for DNA is important to avoid degradation of DNA. Preliminary studies were conducted on Ocimum gratissimum L. in order to establish the storage conditions for the collected samples before DNA extraction. Secondly, the aim was to determine the best protocol for the extraction of high quality DNA, which would later be used for molecular analysis. DNA was extracted from the samples one month after field sampling. During the DNA extraction, four protocols were used; the modified hexadecyltrimethyl ammonium bromide (CTAB) mini preparation method described by Doyle and Doyle (1990), with reductants either mercaptoethanol or dithiothreitol; the modified sodium dodecyl sulphate (SDS) mini preparation method of Edwards et al. (1991) with redundant either mercaptoethanol or dithiothreitol. The DNA was purified, treated with RNase, quantified and examined for intactness using gel electrophoresis method. Good quality and high yield DNA could only be extracted with the buffer containing the detergent SDS and the reducing agent dithiothreiotol.
Characterization of Kenyan sweet potato genotypes for SPVD resistance and high dry matter content using simple sequence repeat markers
HW Karuri, EM Ateka, R Amata, AB Nyende, AWT Muigai
African Journal of Biotechnology , 2009,
Abstract: Simple sequence repeat (SSR) markers were used to characterize Kenyan sweet potato genotypes for resistance to the sweet potato virus disease (SPVD) and high dry matter content. Eighty nine (89) genotypes with a mean symptom severity score of between 1 and 1.5 were selected following graft inoculation with SPVD-infected scions and characterized using 6 SSR primers. The 6 SSR primer pairs had an average polymorphic information content (PIC) of 0.47. The average number of alleles within the 89 genotypes across the 6 loci was 13.52. Cluster analyses revealed a 50% variation among the 89 genotypes. The dendrogram did not reveal any unique clustering of the genotypes according to dry matter content and reaction to SPVD. The genetic differences among the SPVD resistant genotypes and those with high dry matter revealed by the distinct groups suggest a significant genetic variability and the presence of different sources of resistance to SPVD and high dry matter. This characterization will give valuable information for breeders and serve as a baseline for efficient development of new cultivars resistant to SPVD and containing high dry matter.
Characterization of sheep populations of Kenya using microsatellite markers: Implications for conservation and management of indigenous sheep populations
AWT Muigai, AM Okeyo, AK Kwallah, D Mburu, O Hanotte
South African Journal of Animal Science , 2010,
Abstract: Indigenous sheep of Kenya are very important to resource-poor farmers and pastoralists. They have over time adapted to the harsh environmental conditions of the arid and semi-arid lands where they are faced with challenges of persistent droughts, diseases, conflicts and poor nutrition, yet show resistance to gastrointestinal nematodes. In recent years, these indigenous sheep populations have been crossbred indiscriminately to exotic breeds particularly the Dorper. A study was undertaken to determine the level of genetic diversity and relatedness between the various sheep populations and breeds of Kenya. This paper reports results on the genetic diversity and admixture observed using microsatellite DNA markers.
Carriage rate and serotypes of Streptococcus pneumoniae amongst children in Thika Hospital, Kenya
Susan Githii,Gunturu Revathi,Anne Muigai,Samuel Kariuki
African Journal of Laboratory Medicine , 2013, DOI: 10.4102/ajlm.v2i1.45
Abstract: Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide. Rates of carriage are highest in infants and the elderly. The objectives of this study were to determine the rate of nasopharyngeal colonization by S. pneumoniae, and to describe the antibiotic resistant patterns and the serotypes of the carried isolates. A cross-sectional study design was used. Nasopharyngeal swabs were collected from 315 children in the months of Octoberand November 2010 and processed to isolate S. pneumoniae. The isolates were serotyped by the Quellung reaction and their antibiotic susceptibilities assessed by the disc diffusion method. The overall nasopharyngeal carriage rate for S. pneumoniae was 17%. Seventeen serotypes were detected amongst 55 strains analysed: 6A, 23F, 19F, 13, 6B, 14A, 20, 7C, 1,15B, 35B, 19A, 11A, 34, 5, 3 and 23A. Susceptibility testing revealed that nearly all (98%) were resistant to cotrimoxazole, 9% were resistant to penicillin and 7% to cefotaxime. Resistance to chloramphenicol and erythromycin was 2% and 4%, respectively. All isolates were fully sensitive to tetracycline. High levels of cotrimoxazole resistance and some resistance to other antimicrobial agents commonly used in Thika District Hospital shows that there is need to revise antimicrobial policy in this region in the treatment of invasive pneumococcal infections. The frequent serotypes found in this study have previously been associated with pneumococcal infectionsin children. Several of these serotypes are included in the ten-valent vaccine and therefore useof this vaccine will help reduce pneumococcal infections in Thika.
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