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Background: Enterobacter cloacae causes nosocomial infections in 15% of patients in low- and middle-income countries with emergence of carbapenem resistance. The utilisation of bacteriophages for therapeutic purposes is crucial for eradicating these resistant bacterial strains. Objective: This study evaluated the efficacy of lytic phages on bacterial isolates of E. cloacae and determined their stability in various physicochemical conditions. Methods: Twenty-nine lytic phages were isolated from the waste water of six informal settlements in Nairobi County, Kenya, from July 2019 to December 2020 and cross-reacted with 30 anonymised clinical isolates of E. cloacae. Six phages were then selected for physicochemical property studies. Phages were described as potent upon lysing any bacterial strain in the panel. Results: Selected phages were stable at 4 °C - 50 °C with a 5.1% decrease in titre in four of six phages and a 1.8% increase in titre in two of six phages at 50 °C. The phages were efficient following two weeks incubation at 4 °C with optimal activity at human body temperature (37 °C) and an optimal pH of 7.5. Phages were active at 0.002 M and 0.015 M concentrations of Ca2+ ions. The efficiency of all phages decreased with increased exposure to ultraviolet light. All phages (n = 29) showed cross-reactivity against anonymised clinical isolates of E. cloacae strains (n = 30). The most potent phage lysed 67.0% of bacterial strains; the least potent phage lysed 27.0%. Conclusion: This study reveals the existence of therapeutic phages in Kenya that are potent enough for treatment of multi-drug resistant E. cloacae.
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BACKGROUND: Malaria vector control has been implemented chiefly through indoor interventions targeting primary vectors resulting in population declines-pointing to a possible greater proportional contribution to transmission by secondary malaria vectors with their predominant exophagic and exophilic traits. With a historical focus on primary vectors, there is paucity of data on secondary malaria vectors in many countries in Africa. This study sought to determine the species compositions and bionomic traits, including proportions infected with Plasmodium falciparum and phenotypic insecticide resistance, of secondary vectors in three sites with high malaria transmission in Kisumu County, western Kenya. METHODS: Cross-sectional sampling of adult Anopheles was conducted using indoor and outdoor CDC light traps (CDC-LT) and animal-baited traps (ABTs) in Kakola-Ombaka and Kisian, while larvae were sampled in Ahero. Secondary vectors captured were exposed to permethrin using WHO bioassays and then analyzed by ELISA to test for proportions infected with P. falciparum sporozoites. All Anopheles were identified to species using morphological keys with a subset being molecularly identified using ITS2 and CO1 sequencing for species identification. RESULTS: Two morphologically identified secondary vectors captured-An. coustani and An. pharoensis-were determined to consist of four species molecularly. These included An. christyi, An. sp. 15 BSL-2014, an unidentified member of the An. coustani complex (An. cf. coustani) and a species similar to that of An. pharoensis and An. squamosus (An. cf. pharoensis). Standardized (Anopheles per trap per night) capture rates demonstrate higher proportions of secondary vectors across most trapping methods-with overall indoor and outdoor CDC-LTs and ABT captures composed of 52.2% (n = 93), 78.9% (n = 221) and 58.1% (n = 573) secondary vectors respectively. Secondary vectors were primarily caught outdoors. The overall proportion of secondary vectors with P. falciparum sporozoite was 0.63% (n = 5), with the unidentified species An. cf. pharoensis, determined to carry Plasmodium. Overall secondary vectors were susceptible to permethrin with a > 99% mortality rate. CONCLUSIONS: Given their high densities, endophily equivalent to primary vectors, higher exophily and Plasmodium-positive proportions, secondary vectors may contribute substantially to malaria transmission. Unidentified species demonstrate the need for further morphological and molecular identification studies towards further characterization. Continued monitoring is essential for understanding their temporal contributions to transmission, the possible elevation of some to primary vectors and the development of insecticide resistance.
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Anopheles/parasitología , Malaria/epidemiología , Malaria/transmisión , Mosquitos Vectores/parasitología , Animales , Anopheles/clasificación , Estudios Transversales , Ecología , Conducta Alimentaria , Femenino , Resistencia a los Insecticidas , Kenia/epidemiología , Malaria/parasitología , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Malaria Falciparum/transmisión , Control de Mosquitos/métodos , Mosquitos Vectores/clasificaciónRESUMEN
BACKGROUND: Information about HBV sero-markers, infection stages and genotypes in HIV-1 infected and uninfected injection and non-injection drug users (IDUs) in Kenya remains elusive. METHODS: A cross-sectional study examining HBV sero-marker, infection stages and genotypes was conducted among HIV-1 infected and uninfected, respectively, IDUs (n = 157 and n = 214) and non-IDUs (n = 139 and n = 48), and HIV-1 uninfected non-drug using controls (n = 194) from coastal, Kenya. HBV sero-marker and infection stages were based on HBV 5-panel rapid test plasma sero-reactivity. DNA was extracted from acute and chronic plasma samples and genotypes established by nested-PCR and direct sequencing. RESULTS: HBsAg positivity was higher in HIV-1 infected IDUs (9.6%) relative to HIV-1 uninfected IDUs (2.3%), HIV-1 infected non-IDUs (3.6%), HIV-1 uninfected non-IDUs (0.0%) and non-drug users (2.6%; P = 0.002). Contrastingly, HBsAb positivity was higher in HIV-1 uninfected IDUs (14.6%) and non-IDUs (16.8) in comparison to HIV-1 infected IDUs (8.3%), and non-IDUs (8.6%), and non-drug users (8.2%; P = 0.023). HBcAb positivity was higher in HIV-1 infected IDUs (10.2%) compared to HIV-1 uninfected IDUs (3.3%), HIV-1 infected non-IDUs (6.5%), HIV-1 uninfected non-IDUs (2.1%) and non-drug users (4.6%; P = 0.038). Acute (5.7%, 1.4%, 0.0%, 0.0% and 1.5%) and chronic (5.1%, 0.9%, 3.6%, 0.0% and 1.5%) stages were higher in HIV-1 infected IDUs, compared to HIV-1 uninfected IDUs, HIV-1 infected and uninfected non-IDUs and non-drug users, respectively. However, vaccine type response stage was higher in HIV-1 uninfected IDUs (15.4%) relative to HIV-1 infected IDUs (6.4%), and HIV-1 infected (6.5%), and uninfected (10.4%) non-IDUs, and non-drug users (5.7%; P = 0.003). Higher resolved infection rates were also recorded in HIV-1 uninfected IDUs (11.2%) compared to HIV-1 infected IDUs (8.3%), and HIV-1 infected (7.2%), uninfected (6.3%) non-IDUs, and non-drug users (6.7%; P = 0.479), respectively. Only A1 genotype showing minimal diversity was detected among the study participants. CONCLUSION: HBV sero-markers and infection staging are valuable in diagnosis and genotyping of HBV infections. Among IDUs, higher HBsAg and HBcAb positivity in HIV-1 infected and higher HBsAb positivity in HIV-1 negative IDUs suggests frequent exposure. Additionally, HBV genotype A is the dominant circulating genotype in both high and low risk populations of Kenya.
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Consumidores de Drogas , Genotipo , Infecciones por VIH/sangre , VIH-1 , Virus de la Hepatitis B , Hepatitis B/sangre , Adolescente , Adulto , Biomarcadores/sangre , Estudios Transversales , Consumidores de Drogas/estadística & datos numéricos , Femenino , Anticuerpos Anti-VIH/análisis , Anticuerpos Anti-VIH/sangre , Infecciones por VIH/complicaciones , Infecciones por VIH/epidemiología , VIH-1/genética , VIH-1/inmunología , Anticuerpos Antihepatitis/análisis , Anticuerpos Antihepatitis/sangre , Hepatitis B/complicaciones , Hepatitis B/diagnóstico , Hepatitis B/epidemiología , Antígenos de Superficie de la Hepatitis B/inmunología , Virus de la Hepatitis B/genética , Virus de la Hepatitis B/inmunología , Humanos , Kenia/epidemiología , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Pruebas Serológicas , Abuso de Sustancias por Vía Intravenosa/sangre , Abuso de Sustancias por Vía Intravenosa/complicaciones , Abuso de Sustancias por Vía Intravenosa/epidemiología , Adulto JovenRESUMEN
BACKGROUND: The enumeration of absolute CD4 counts is of primary importance for many medical conditions especially HIV infection where therapeutic initiation depends on the count. These ranges tend to vary across populations. However, these ranges have not been comprehensively established in the Kenyan population. Therefore, this study aimed at establishing the reference ranges for the CD4 and CD8 T-lymphocytes in normal healthy individuals in Kenya. METHODS: A total of 315 individuals of the ages between 16 and 60 years old, in 5 different regions of the country, were recruited into the study. They were screened for diseases that potentially cause lymphocyte homeostasis perturbation. CD4/CD8 Counts were performed by use of a FACSCalibur flow cytometer (Becton-Dickinson, NJ) equipped with automated acquisition and analysis software. Results were analysed according to age, sex and region. RESULTS: Results were presented as means and ranges (in parenthesis) generated non parametrically as 2.5 and 97.5 percentiles as follows; In general population; CD3 1655 (614-2685 cells/µL ), CD4 920 (343-1493 cells/µL), and CD8 646 (187-1139 cells/µL), while according to sex, females; CD3 1787 (697-2841 cells/µL), CD4 1010 (422-1572 cells/µL), CD8 659 (187-1180 cells/µL); males; CD3 1610 (581-2641 cells/µL), CD4 889(320-1459 cells/µL) and CD8 644 (185-1140 cells/µL). The general reference ranges for CD4/CD8 ratios were as follows; general population 1.57(0.50-2.74), males 1.51(0.49-2.64) and females 1.69(0.55-2.95). CONCLUSION: The lymphocyte reference ranges for the Kenyan population are fairly comparable to those established in other African populations. The ranges also differ appreciably from those established in Germany, Italy and Switzerland. Furthermore, the study reported significant differences in the ranges of different population clusters within Kenya, as well us between males and females.