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Bacteriophages Isolated in China for the Control of Pectobacterium carotovorum Causing Potato Soft Rot in Kenya

Virologica Sinica 2019年第3期34卷 287-294页

作者： Peter Muturi Junping Yu Alice Nyambura Maina samuel kariuki Frantis B.Mwaura Hongping Wei Key Laboratory of Emerging Pathogens and Biosafety Wuhan Institute of VirologyChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China Centre for Microbiology Research Kenya Medical Research InstituteNairobi 00202Kenya School of Biological and Life Sciences Technical University of KenyaNairobi 00200Kenya School of Biological Sciences University of NairobiNairobi 00100Kenya Sino-Africa Joint Research Centre Nairobi 00200Kenya

Soft rot is an economically significant disease in potato and one of the major threats to sustainable potato *** study aimed at isolating lytic bacteriophages and evaluating methods for and the efficacy of applying phages to control potato soft rot caused by Pectobacterium *** bacteriophages isolated from soil and water samples collected in Wuhan,China,were used to infect *** host strains isolated from potato tubers showing soft rot symptoms in Nakuru county,*** efficacy of the phages in controlling soft rot disease was evaluated by applying individual phage strains or a phage cocktail on potato slices and tubers at different time points before or after inoculation with a *** *** phages could lyse 20 strains of ***,but not Pseudomonas fluorescens control *** the 11 phages,Pectobacterium phage Wc5r,interestingly showed cross-activity against Pectobacterium atrosepticum and two phage-resistant *** *** slice assays showed that the phage concentration and timing of application are crucial factors for effective soft rot *** cocktail applied at a concentration of 1×10^9 plaque-forming units per milliliter before or within an hour after bacterial inoculation on potato slices,resulted in>90%reduction of soft rot *** study provides a basis for the development and application of phages to reduce the impact of potato soft rot disease.

关键词： Pectobacterium carotovorum Potato soft rot Bacteriophages Phage resistance

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Escherichia coli Pathotypes in Children with Acute Diarrhea in an Informal Settlement in Nairobi, Kenya

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Advances in Microbiology 2023年第4期13卷 181-192页

作者： Moureen Jepleting Winnie Mutai Victor Moses Musyoki Beatrice Oduor Charchil Ayodo Robert Mugoh samuel kariuki Sylvia Omulo Washington State University Global Health-Kenya Nairobi Kenya University of Nairobi Institute of Tropical and Infectious Diseases Nairobi Kenya Department of Medical Microbiology University of Nairobi Kenya Centre for Microbiology Research Kenya Medical Research Institute Nairobi Kenya Paul G. Allen School for Global Health Washington State University Pullman USA

Diarrhea is among the leading causes of morbidity and mortality in children aged Escherichia coli (DEC) accounts for 30% - 40% of childhood diarrhea cases. To identify the pathotypes involved in diarrheal outbreaks in Kenya, we analyzed archived E. coli isolates from children E. coli confirmation and antimicrobial susceptibility testing were done using the VITEK®2 instrument. Pathotype identification was performed via conventional polymerase chain reaction. Of 175 E. coli isolates, 48 (27%) were DEC pathotypes, with enteroaggregative E. coli (EAEC) predominating (71%, 34/48). Enterohemorrhagic (EHEC) and enteropathogenic E. coli (EPEC) represented 19% and 10% of isolates, respectively. Enteroinvasive and enterotoxigenic pathotypes were not identified. All DEC isolates were susceptible to amikacin, ertapenem, imipenem, meropenem and tigecycline. Conversely, most (>80%) isolates were resistant to ampicillin, ampicillin-sulbactam and sulfamethoxazole-trimethoprim. Half of all EAEC and EPEC strains were resistant to cefazolin while half of EHEC isolates were resistant to ciprofloxacin and moxifloxacin. In total, 18 resistance phenotypes were identified with “ampicillin-cefazolin-ampicillin/ sulbactam-sulfamethoxazole/trimethoprim” predominating (33%, 16/48). The majority (81%) of DEC isolates were multidrug-resistant, with extended-spectrum beta-lactamase production identified in 8% of these isolates. This study highlights the predominance of Enteroaggregative E. coli and multidrug resistance of DEC pathotypes. Studying the epidemiology of diarrheal disease and antimicrobial resistance surveillance, will aid in identifying dominant etiological agents of diarrhea and newly emerging resistant strains in informal settlements.

关键词： E. coli Pathotypes Children Diarrhoea Informal Settlement Multidrug Resistance

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Detection and Characterization of Methicillin Resistant Staphylococcus aureus from Toilet and Classroom Door Handles in Selected Secondary Schools in Nairobi County

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Open Journal of Medical Microbiology 2013年第4期3卷 248-252页

作者： Caroline Mbogori Anne Muigai samuel kariuki Centres for Microbiology Research KEMRI Nairobi Kenya Jomo Kenyatta University of Agriculture and Technology Itromid KEMRI Nairobi Kenya

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.

关键词： Methicillin Resistant Staphylococcus aureus Secondary Schools Antibiotic Patterns

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Exposure to sublethal concentration of flupyradifurone alters sexual behavior and cuticular hydrocarbon profile in Heriades truncorum,an oligolectic solitary bee

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Insect Science 2024年第3期31卷 859-869页

作者： samuel Boff Manfred Ayasse Institute of Evolutionary Ecology and Conservation Genomics Ulm UniversityUlmGermany

The aboveground oligolectic bee,Heriades truncorum,is a particularly good model for studying the impact of pesticides on sexual communication,since some aspects of its mating behavior have previously been *** have tested(1)the interference of the pesticide flupyradifurone on male precopulatory behavior and male mating partner preferences,(2)the way that the pesticide interferes in male quality assessment by the female,and(3)the effects of the pesticide on the chemical compounds in the female *** exposed bees of both sexes to a sublethal concentration of *** behaviors were registered in a mating arena with two females(one unexposed and one exposed)and one male(either unexposed or exposed).Unexposed males were quicker to attempt to *** also impacted precopulatory behavior and male quality assessment by *** approached unexposed females more quickly than insecticideexposed *** exposed to insecticide produced lower amounts of some cuticular hydrocarbons(sex pheromone candidates)and appeared less choosy than unexposed *** findings suggest that insecticide exposure affects sexual communication,playing a role both in male preference and in male quality assessment by the female.

关键词： courtship display female choice flupyradifurone male partner preference sex communication sublethal effects

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Prevalence of Panton Valentine Leukocidin in Carriage and Infective Strains of <i>Staphylococcus aureus</i>at a Referral Hospital in Kenya

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Open Journal of Medical Microbiology 2013年第1期3卷 5-11页

作者： Geoffrey Omuse Patricia Shivachi samuel kariuki Gunturu Revathi Center of Microbiology Research Kenya Medical Research Institute Nairobi Kenya Department of Pathology Aga Khan University Hospital Nairobi Kenya Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya

Panton valentine leukocidin (PVL) is a pore forming exotoxin that is expressed by some Staphylococcus aureus (S. aureus) strains and is thought to add to its virulence. The prevalence of PVL in carriage and disease causing strains varies considerably from region to region. This study compared the prevalence of the PVL gene in S. aureus isolates obtained from healthcare workers and from patients seen at the Aga Khan University Hospital Nairobi (AKUHN). S. aureus isolates obtained from healthcare workers and patients attended to at AKUHN between July 2010 and March 2011 were used for this study. Forty five S. aureus isolates from healthcare workers and 63 from clinical specimens obtained from 59 patients were analysed for the PVL gene. The prevalence of PVL in isolates from healthcare workers was 24.4% compared to 39.7% in the isolates causing infection (P = 0.098). PVL prevalence was 58.8% in S. aureus isolates obtained from skin and soft tissue infections (SSIs) compared to 25.0% in carriage isolates (P = 0.002, OR 4.29). Prevalence in isolates from invasive infections was 11.1%. Patients with PVL positive S. aureus were younger than those with PVL negative isolates (P = 0.082). The high prevalence of PVL is comparable with that reported in other African countries. The significance of the high prevalence of PVL in *** isolates carried by health care workers at AKUHN is unclear at the moment. PVL prevalence is significantly higher in S. aureus isolates causing SSIs compared to carriage and invasive isolates.

关键词： Staphylococcus aureus S. aureus Panton Valentine Leukocidin PVL

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The influence of various grease compositions and silver nanoparticle additives on electrically induced rolling-element bearing damage

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Friction 2024年第4期12卷 796-811页

作者： samuel BOND Robert L.JACKSON German MILLS Department of Chemistry and Biochemistry Auburn UniversityAuburn 36849-5412USA Department of Mechanical Engineering Auburn UniversityAuburn 36849-5412USA

Leakage currents accelerate surface degradation of metal contacts via small scale arcing across lubricating films,but recent observations suggest that metallic nanoparticle additives in lubricants may be useful to improve contact *** findings prompted a study that examined electrically induced surface pitting of steel contacts in the presence of several lubricating greases including some containing nanometer-sized colloidal silver(Ag)*** rolling sphere-on-disk experiments were conducted under electro-tribological loads employing polyurea greases derived from mineral and synthetic base oils with and without *** forces and electrical resistance were monitored continuously during the tests;surface changes were characterized by means of optical spectroscopy,stylus profilometry,and scanning electron microscopy(SEM)including compositional analysis using energy dispersive spectroscopy(EDS).The observations demonstrate that surface pitting induced by arcing occurs mainly at the points were the rolling motion changes direction and that eroded metal is deposited along the wear ***-sized pits are formed which contain carbon and oxygen indicating that arcing causes decomposition of the hydrocarbon *** findings indicate a significant inhibition of pitting is induced by the Ag nanoparticles;some greases containing other additives exhibit a similar,although less pronounced,effect.

关键词： electric motor bearings wheel bearings electric vehicles arcing electrically induced bearing damage pitting leakage current stray current

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Antimicrobial Susceptibility and Genetic Basis of Resistance of <i>Klebsiella spp</i>Isolated from Diarrheic and Non-Diarrheic Children at Health Facilities in Mukuru Informal Settlement, Nairobi, Kenya

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Advances in Microbiology 2021年第10期11卷 554-578页

作者： Celestine Wanjiku Wairimu Eddy Okoth Odari Celestine Khalechi Makobe samuel kariuki Department of Medical Microbiology College of health Science Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya Centre for Microbiology Research Kenya Medical Research Institute Nairobi Kenya

Antimicrobial resistance (AMR) is a global threat to public health and particularly to children. This study aimed to determine the prevalence of multidrug resistance of fecal Klebsiella spp on selected beta lactam (3rd generation cephalosporins and carbapenems) and fluoroquinolone classes of drugs in four health facilities serving the slum communities of Nairobi city in Kenya. Additionally, determine the genetic basis for the multidrug resistance observed. A cross sectional laboratory based study was undertaken where a total of 1171 children below 16 years were selected, from whom stool samples were collected, tested and analyzed. 395 (33.73%) Klebsiella spp were isolated, consisting of 365 (92.4%) Klebsiella pneumoniae and 30 (7.6%) Klebsiella oxytoca were isolated. The proportion of multi-drug resistance (MDR) K. pneumoniae and MDR K. oxytoca was 64.1% (234/365) and 96.67% (29/30) respectively. Third generation cephalosporins, cefotaxime ceftriaxone and ceftazidime showed the highest resistance of 30.7%, 29.9% and 27.4% respectively, whereas carbapenems including imipenem and meropenem had the least resistance of 1.6%, each, to K. pneumoniae. A significant association was observed in diarrheic children (OR = 1.88;p = 0.01) and those below 50 months (OR = 0.43;p = 0.002) and carrying K. pneumoniae resistance to one or more third generation cephalosporins. Genes associated with resistance included bla TEM 100%, bla CTX-M 95.2%, bla SHV 57.1%, bla OXA-1 66.7%, qnrS 54.1%, qnrB 47.6% and bla NDM 7.1%. In conclusion, there’s need for more effective infection control measures, antimicrobial stewardship to reduce emergence of antimicrobial resistance, improved drinking water, sanitation and hygiene (WASH) practices.

关键词： Klebsiella Antimicrobial Resistance Carriage Community Children Slums Kenya

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Risk Factors in the Transmission of Tuberculosis in Nairobi: A Descriptive Epidemiological Study

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Advances in Microbiology 2013年第2期3卷 160-165页

作者： Perpetual Wangui Ndungu Gunturu Revathi samuel kariuki Zipporah Ng’ang’a Institute of Tropical Medicine and Infectious Diseases (ITROMID) Jomo Kenyatta University of Agriculture and Technology (JKUAT) Nairobi Kenya

Background: Tuberculosis is an infectious disease with an estimated 1.45 million deaths every year. Many patients get infected as a result of ignorance of the risk factors that contribute to disease transmission. Methodology: A descriptive epidemiological study was conducted on 258 patients presenting with pulmonary tuberculosis. Patients’ sputa were collected for laboratory analysis and patients were required to respond to a structured questionnaire on risk factors for transmission. Data among stratified groups were compared using bivariate analysis. Statistical significance was considered at p Results: There were significantly more males than females associated with pulmonary tuberculosis infection (χ2 = 0.963;df = 1;p (64.3%) patients were living in single rooms with 110 (42.6%) living with more than two people with a maximum of 10 people in a single room. Only 73 (28.3%) were living alone in a single room and only 7 families (2.7%) were living in houses with five or more rooms. Alcohol consumers and smokers were 102 (39.5%) and 93 (36%) respectively. Half of the patients (137 (53.3%)) had not completed secondary education with only 16 (6.2%) having completed tertiary education. Recurrent cases were 54 (21%) while those exposed to the disease either at home or working place were 75 (29.2%). Out of 171 patients who agreed to test for HIV, 46 (26.9%) were positive. Marital status had no effect on incidence of disease. Conclusion: Emphasis should be given to creating awareness of the risk factors associated with transmission of tuberculosis in order to reduce the rate of infection.

关键词： Tuberculosis Risk Factors Transmission

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Fish-on-Chips:unveiling neural processing of chemicals in small animals through precise fluidic control

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Neural Regeneration Research 2024年第11期19卷 2351-2353页

作者： samuel K.H.Sy Ho Ko Division of Neurology Department of Medicine and TherapeuticsFaculty of MedicineThe Chinese University of Hong KongShatinNew TerritoriesHong Kong Special Administrative RegionChina Li Ka Shing Institute of Health Sciences Faculty of MedicineThe Chinese University of Hong KongShatinNew TerritoriesHong Kong Special Administrative RegionChina Department of Electrical and Electronic Engineering Faculty of EngineeringThe University of Hong KongPok Fu LamHong Kong IslandHong Kong Special Administrative RegionChina Advanced Biomedical Instrumentation Center Hong Kong Science ParkPak Shek KokNew TerritoriesHong Kong Special Administrative RegionChina Margaret K.L.Cheung Research Center for Management of Parkinsonism Faculty of MedicineThe Chinese University of Hong KongShatinNew TerritoriesHong Kong Special Administrative RegionChina Lau Tat-chuen Research Center of Brain Degenerative Diseases in Chinese Faculty of MedicineThe Chinese University of Hong KongShatinNew TerritoriesHong Kong Special Administrative RegionChina Gerald Choa Neuroscience Institute The Chinese University of Hong KongShatinNew TerritoriesHong Kong Special Administrative RegionChina

Precise chemical cue presentation alongside advanced brainwide imaging techniques is important to the study of chemosensory processing in ***,the dynamic nature of chemical-carrying media,such as water or air,poses a significant challenge for delivering highly-controlled chemical flow to an animal ***,contact-based cue manipulation and delivery easily shift the position of the animal subject,which is often undesirable for high-quality brain ***,more advanced interfacing tools that align with the diverse range of body part sizes of an animal,ranging from micrometer-scale neurons to meter-long limbs,are much *** is particularly crucial when dealing with dimensions that are beyond the reach of conventional experimental tools.

关键词： dealing precise sizes

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Soluble p75 neurotrophic receptor as a reliable biomarker in neurodegenerative diseases: what is the evidence?

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Neural Regeneration Research 2024年第3期19卷 536-541页

作者： Georges Jourdi samuel Fleury Imane Boukhatem Marie Lordkipanidzé Research Center Montreal Heart InstituteMontrealQCCanada Faculty of Pharmacy Universitéde MontréalMontrealQCCanada UniversitéParis Cité INSERMInnovative Therapies in HaemostasisParisFrance Service d’Hématologie Biologique AP-HPHôpital LariboisièreParisFrance

Neurodegenerative diseases are often misdiagnosed,especially when the diagnosis is based solely on clinical *** p75 neurotrophic receptor(p75^(NTR))has been studied as an index of sensory and motor nerve development and *** cleavable extracellular domain(ECD)is readily detectable in various biological fluids including plasma,serum and *** is evidence for increased p75NTR ECD levels in neurodegenerative diseases such as Alzheimer’s disease,amyotrophic lateral sclerosis,age-related dementia,schizophrenia,and diabetic *** p75^(NTR) ECD could be used as a biomarker for diagnosis and/or prognosis in these disorders,and whether it could potentially lead to the development of targeted therapies,remains an open *** this review,we present and discuss published studies that have evaluated the relevance of this emerging biomarker in the context of various neurodegenerative *** also highlight areas that require further investigation to better understand the role of p75^(NTR) ECD in the clinical diagnosis and management of neurodegenerative disorders.

关键词： Alzheimer’s disease amyotrophic lateral sclerosis biomarker dementia diabetic neuropathy nerve growth factor receptor(NGFR) neurodegeneration p75^(NTR) schizophrenia

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