Bacteriophages as therapeutic & disinfectant agents to tackle multidrug-resistant Acinetobacter baumannii

Background & objectives: Multidrug-resistant (MDR) Acinetobacter baumannii is a serious threat for human health worldwide. The studies on agents targeting A. baumannii are imperative due to identified A. baumannii co-infections in COVID-19. Bacteriophages are promising antibacterial agents against drug-resistant bacteria. This study intended to isolate bacteriophages against MDR A. baumannii from the water of river Ganga, to be used potentially as therapeutic and disinfectant particles. Methods: Acinetobacter phages were isolated from the Ganga water collected from Kanpur and further tested on 50 MDR A. baumannii isolates to determine host range. The phages were morphologically characterized by transmission electron microscopy. The disinfectant property of the isolated phages was tested by spraying of bacteriophage cocktail on MDR A. baumannii contaminated plastic surface, analyzed by colony-forming unit (CFU) and bioluminescence assay (adenosine triphosphate monitoring). Results: A total of seven bacteriophages were isolated against MDR A. baumannii. The bacteriophages lysed three MDR A. baumannii isolates out of 50 tested, showing narrow host range. Electron microscopy revealed hexagonal heads and long tails of bacteriophages, belonging to order Caudovirales. The bacteriophage cocktail reduced the MDR A. baumannii load efficiently on plastic surface, evidenced by reduction in CFUs and bioluminescence. Interpretation & conclusions: The findings of this study suggest that the isolated bacteriophages are potential lytic agents for MDR A. baumannii clinical isolates, and may be used as potential therapeutic agents as well as disinfectant to combat MDR A. baumannii with due consideration to phage host specificity, with further characterization.n

Research progress of phage display vaccine / 中国生物制品学杂志

@#Bacteriophages are viruses that infect microorganisms such as bacteria,fungi,actinomycetes and spirochetes.Because of the inherent immunogenicity,genetic plasticity,stability,safety and many other advantages,it has unique potential in vaccine research and development. At present,there are countless researches using it to construct vaccine delivery platforms,mainly including three forms,phage display vaccine,phage DNA vaccine and hybrid phage DNA vaccine,of which the phage display vaccine is the most widely studied. Phage display technology is a novel vaccine preparation technology,which is a molecular biology technology using phage as carrier,integrating foreign polypeptide or protein genes into phage genes and displaying them on the surface of phage in the form of fusion protein. This review mainly elaborated the immunological basis of phage display vaccine,the display system and its application in disease prevention,so as to provide a reference for the development and application of phage display vaccine.

Clinical application strategies of bacteriophage in treatment of nontuberculous mycobacteriosis / 中华临床感染病杂志

Nontuberculous mycobacteria(NTM) diseases have become an important global public health problem attracting more and more attention because of its increasing morbidity. Mycobacteria show intrinsic and acquired resistance to multiple antibiotics, leading to higher difficulty and longer duration of treatment, and more uncertain prognosis than tuberculosis due to limited therapeutic measures. Bacterial phages are viruses that kill bacteria specifically, phage therapy for bacterial infection has been used for almost one century, now become a hot spot. This article reviews the biological characteristics, gene engineering of mycobacteriophages and its clinical applications; also discusses the existing problems in treatments of NTM with bacteriophages.

Assessment of genotyping markers in the molecular characterization of a population of clinical isolates of Fusarium in Colombia / Evaluación de marcadores de genotipificación en la caracterización molecular de una población de aislamientos clínicos de Fusarium en Colombia

Introduction: Fusarium is a very heterogeneous group of fungi, difficult to classify, with a wide range of living styles, acting as saprophytes, parasites of plants, or pathogens for humans and animals. Prevalence of clinical fusariosis and lack of effective treatments have increased the interest in the precise diagnosis, which implies a molecular characterization of Fusarium populations. Objective: We compared different genotyping markers in their assessment of the genetic variability and molecular identification of clinical isolates of Fusarium. Materials and methods: We evaluated the performance of the fingerprinting produced by two random primers: M13, which amplifies a minisatellite sequence, and (GACA)4, which corresponds to a simple repetitive DNA sequence. Using the Hunter Gaston Discriminatory Index (HGDI), an analysis of molecular variance (AMOVA), and a Mantel test, the resolution of these markers was compared to the reference sequencing-based and PCR genotyping methods. Results: The highest HGDI value was associated with the M13 marker followed by (GACA)4. AMOVA and the Mantel tests supported a strong correlation between the M13 classification and the reference method given by the partial sequencing of the transcription elongation factor 1-alpha (TEF1-α) and rDNA 28S. Conclusion: The strong correlation between the M13 classification and the sequencing-based reference together with its higher resolution demonstrates its adequacy for the characterization of Fusarium populations.

Introducción. Fusarium es un grupo heterogéneo de hongos, difícil de clasificar y con una amplia gama de estilos de vida, que actúa como saprófito, parásito de plantas o patógeno de humanos y animales. La prevalencia de la fusariosis clínica y la falta de tratamientos han incrementado el interés en su diagnóstico preciso, lo que conlleva la caracterización molecular de las poblaciones. Objetivo. Comparar marcadores de genotipificación en la evaluación de la variabilidad genética e identificación de aislamientos clínicos de Fusarium. Materiales y métodos. Se evaluó la huella genética producida por dos cebadores aleatorios: M13, que amplifica una secuencia minisatélite, y (GACA)4, que corresponde a una secuencia repetitiva de ADN. Utilizando el índice discriminatorio de Hunter Gaston (HGDI), el análisis de varianza molecular (AMOVA) y una prueba de Mantel, se comparó la resolución de estos marcadores con métodos de genotipificación basados en secuenciación y PCR. Resultados. El mayor HGDI se asoció con el marcador M13, seguido de (GACA)4. Las pruebas AMOVA y Mantel mostraron correlación entre las clasificaciones obtenidas con M13 y la referencia basada en la secuenciación parcial del factor de elongación de transcripción 1-alfa (TEF1-α) y el ADNr 28S. Conclusión. La fuerte correlación entre la clasificación obtenida con M13 y el método de referencia, así como su alta resolución, demuestran su idoneidad para la caracterización de poblaciones de Fusarium.

Detection on antiserum of Yersinia pestis phage in Marmota himalayana blood in the natural plague foci of Qinghai-Tibet Plateau / 中国热带医学

@#Abstract: Objective　To detect and analyze the antiserum of Yersinia pestis phage in Marmota himalayana blood from the natural plague foci of Qinghai-Tibet Plateau by micro-bolus technique, to provide a theoretical basis for interaction between phages and mammalian immunology, phage therapy and interaction between bacteriophage and ecology in future. Methods　Using diagnostic Yersinia pestis phage and 3 wild plague phages from Qinghai-Tibet Plateau Natural Plague Foci as antigens, 847 serums of Marmota Himalayana blood, from Tongde, Guinan, Gonghe, Xinghai, Tianjun foci counties in Qinghai Plateau, were collected from July to September in 2020, 2021 and determined on antiserum of Yersinia pestis phage by microplate method and double agar plate method. Results　The neutralization reaction experiment lasted for 24 hours between 4 phage and 847 serums by microplate method independently. These mixtures were tested by double agar plate method. All results were negative on antiserum of Yersinia pestis bacteriophage. Conclusions　The positive antiserum of Yersinia pestis phage in Marmota himalayana were not found the natural plague foci of Qinghai-Tibet Plateau, which agreed with plague epidemiology in 5 foci counties in Qinghai plateau from 2020-2021, that was a characteristic of the resting period. In other words, it was in the absence of plague pathogen. It also showed indirectly that the absence or weak presence of Yersinia pestis bacteriophage in the plague foci. It showed a lower frequency on host animals coming into contact with phages naturally. The antiserum of Yersinia pestis phage may be related to the form of plague infection and the intensity of the disease.

Characterization of a Coliphage AS1 isolated from sewage effluent in Pakistan / Caracterização de um colifago AS1 isolado de efluente de esgoto no Paquistão

The emergence of multi-drug resistant (MDR) bacterial strains, which are posing a global health threat has developed the interest of scientists to use bacteriophages instead of conventional antibiotics therapy. In light of an increased interest in the use of phage as a bacterial control agent, the study aimed to isolate and characterize lytic phages from sewage effluent. During the current study, bacteriophage AS1 was isolated from sewage effluent against E.coli S2. The lytic activity of phageAS1 was limited to E.coli S2 strain showing monovalent behavior. The calculated phage titer was 3.5×109 pfu/ml. PhageAS1 was stable at a wide range of pH and temperature. The maximum stability was recorded at 37ºC and pH 7.0, while showing its normal lytic activity at temperature 60ºC and from pH 5.0 to 11.0 respectively. At temperature 70ºC, phage activity was somewhat reduced whereas, further increase in temperature and decrease or increase in pH completely inactivated the phage. From the current study, it was concluded that waste water is a best source for finding bacteriophages against multi-drug resistant bacterial strains and can be used as bacterial control agent.

O surgimento de cepas bacterianas multirresistentes (MDR), que representam uma ameaça global à saúde, desenvolveu o interesse dos cientistas em usar bacteriófagos em vez da terapia convencional com antibióticos. Diante do crescente interesse no uso de fago como agente de controle bacteriano, o estudo visou isolar e caracterizar fagos líticos de efluente de esgoto. Durante o estudo atual, o bacteriófago AS1 foi isolado de efluente de esgoto contra E. coli S2. A atividade lítica de phageAS1 foi limitada à cepa E. coli S2, apresentando comportamento monovalente. O título de fago calculado foi de 3,5 x 109 ufp/ml. PhageAS1 foi estável em uma ampla faixa de pH e temperatura. A estabilidade máxima foi registrada a 37ºC e pH 7,0, enquanto mostrou atividade lítica normal em temperatura de 60ºC e pH 5,0 a 11,0, respectivamente. Na temperatura de 70ºC, a atividade do fago foi um pouco reduzida, enquanto o aumento adicional da temperatura e a diminuição ou aumento do pH inativaram completamente o fago. Com base no estudo atual, concluiu-se que a água residual é a melhor fonte para encontrar bacteriófagos contra cepas bacterianas multirresistentes e pode ser usada como agente de controle bacteriano.

Characterization of a Coliphage AS1 isolated from sewage effluent in Pakistan

Abstract The emergence of multi-drug resistant (MDR) bacterial strains, which are posing a global health threat has developed the interest of scientists to use bacteriophages instead of conventional antibiotics therapy. In light of an increased interest in the use of phage as a bacterial control agent, the study aimed to isolate and characterize lytic phages from sewage effluent. During the current study, bacteriophage AS1 was isolated from sewage effluent against E.coli S2. The lytic activity of phageAS1 was limited to E.coli S2 strain showing monovalent behavior. The calculated phage titer was 3.5×109 pfu/ml. PhageAS1 was stable at a wide range of pH and temperature. The maximum stability was recorded at 37ºC and pH 7.0, while showing its normal lytic activity at temperature 60ºC and from pH 5.0 to11.0 respectively. At temperature 70ºC, phage activity was somewhat reduced whereas, further increase in temperature and decrease or increase in pH completely inactivated the phage. From the current study, it was concluded that waste water is a best source for finding bacteriophages against multi-drug resistant bacterial strains and can be used as bacterial control agent.

Resumo O surgimento de cepas bacterianas multirresistentes (MDR), que representam uma ameaça global à saúde, desenvolveu o interesse dos cientistas em usar bacteriófagos em vez da terapia convencional com antibióticos. Diante do crescente interesse no uso de fago como agente de controle bacteriano, o estudo visou isolar e caracterizar fagos líticos de efluente de esgoto. Durante o estudo atual, o bacteriófago AS1 foi isolado de efluente de esgoto contra E. coli S2. A atividade lítica de phageAS1 foi limitada à cepa E. coli S2, apresentando comportamento monovalente. O título de fago calculado foi de 3,5 x 109 ufp/ml. PhageAS1 foi estável em uma ampla faixa de pH e temperatura. A estabilidade máxima foi registrada a 37ºC e pH 7,0, enquanto mostrou atividade lítica normal em temperatura de 60ºC e pH 5,0 a 11,0, respectivamente. Na temperatura de 70ºC, a atividade do fago foi um pouco reduzida, enquanto o aumento adicional da temperatura e a diminuição ou aumento do pH inativaram completamente o fago. Com base no estudo atual, concluiu-se que a água residual é a melhor fonte para encontrar bacteriófagos contra cepas bacterianas multirresistentes e pode ser usada como agente de controle bacteriano.

Characterization of a Coliphage AS1 isolated from sewage effluent in Pakistan / Caracterização de um colifago AS1 isolado de efluente de esgoto no Paquistão

The emergence of multi-drug resistant (MDR) bacterial strains, which are posing a global health threat has developed the interest of scientists to use bacteriophages instead of conventional antibiotics therapy. In light of an increased interest in the use of phage as a bacterial control agent, the study aimed to isolate and characterize lytic phages from sewage effluent. During the current study, bacteriophage AS1 was isolated from sewage effluent against E.coli S2. The lytic activity of phageAS1 was limited to E.coli S2 strain showing monovalent behavior. The calculated phage titer was 3.5×109 pfu/ml. PhageAS1 was stable at a wide range of pH and temperature. The maximum stability was recorded at 37ºC and pH 7.0, while showing its normal lytic activity at temperature 60ºC and from pH 5.0 to11.0 respectively. At temperature 70ºC, phage activity was somewhat reduced whereas, further increase in temperature and decrease or increase in pH completely inactivated the phage. From the current study, it was concluded that waste water is a best source for finding bacteriophages against multi-drug resistant bacterial strains and can be used as bacterial control agent.

O surgimento de cepas bacterianas multirresistentes (MDR), que representam uma ameaça global à saúde, desenvolveu o interesse dos cientistas em usar bacteriófagos em vez da terapia convencional com antibióticos. Diante do crescente interesse no uso de fago como agente de controle bacteriano, o estudo visou isolar e caracterizar fagos líticos de efluente de esgoto. Durante o estudo atual, o bacteriófago AS1 foi isolado de efluente de esgoto contra E. coli S2. A atividade lítica de phageAS1 foi limitada à cepa E. coli S2, apresentando comportamento monovalente. O título de fago calculado foi de 3,5 x 109 ufp/ml. PhageAS1 foi estável em uma ampla faixa de pH e temperatura. A estabilidade máxima foi registrada a 37ºC e pH 7,0, enquanto mostrou atividade lítica normal em temperatura de 60ºC e pH 5,0 a 11,0, respectivamente. Na temperatura de 70ºC, a atividade do fago foi um pouco reduzida, enquanto o aumento adicional da temperatura e a diminuição ou aumento do pH inativaram completamente o fago. Com base no estudo atual, concluiu-se que a água residual é a melhor fonte para encontrar bacteriófagos contra cepas bacterianas multirresistentes e pode ser usada como agente de controle bacteriano.

Reducing Salmonella enterica serovar Enteritidis contamination in food: lytic bacteriophages in a homemade mayonnaise-like matrix / Reducción de la contaminación por Salmonella enterica serovar Enteritidis en alimentos: bacteriófagos líticos en una matriz similar a la mayonesa casera / Redução da contaminação por Salmonella enterica serovar Enteritidis em alimentos: bacteriófagos líticos em uma matriz caseira semelhante à maionese

Abstract Background: Salmonella enterica serovar Enteritidis (SE) is one of the major causes of food-borne disease worldwide, mainly associated with the consumption of poultry products, such as eggs. Several control methods have been implemented in the egg production process, but they have not effectively reduced the outbreaks. Therefore, the use of bacteriophages for the biocontrol of food-borne pathogens is gaining increasing acceptance. Objective: To evaluate a bacteriophage cocktail's effectiveness in reducing SE counts in an experimentally contaminated mayonnaise-like matrix. Methods: Homemade mayonnaise was contaminated with SE (103 CFU/ml) with equal volume to a matrix (1:1) treated with a bacteriophage cocktail (five phages, MOI 105), and stored at 21 °C for 24 and 72 h. Bacterial counts were performed to evaluate the bio-controlling activity of the cocktail and compared with a contaminated but not treated group. Results: Significant reductions (up to 3.75 log10 CFU/ml) were observed in the bacteriophage-treated groups (p<0.0001). Conclusions: These results demonstrate the effectiveness of bacteriophages as biocontrol agents for Salmonella Enteritidis in a raw-egg-derivative foodstuff. Further studies are needed to prove the reduction in an undiluted homemade mayonnaise.

Resumen Antecedentes: La Salmonella enterica, serovar Enteritidis (SE), es una de las principales causas de enfermedades transmitidas por alimentos en todo el mundo, asociadas principalmente al consumo de productos avícolas tales como los huevos. Diferentes métodos de control se han ensayado en el proceso de producción de huevos, pero no han sido capaces de reducir eficazmente los brotes de salmonelosis en las personas. Por esta razón, el uso de bacteriófagos para el control biológico de patógenos transmitidos por los alimentos está ganando cada vez más aceptación. Objetivo: Evaluar la eficacia de un cóctel de bacteriófagos para reducir los recuentos de SE en una matriz similar a la de mayonesa contaminada experimentalmente. Método: La mayonesa casera fue contaminada con SE (103 UFC/ml) en igual volumen que la matriz (1:1), tratada con una mezcla de bacteriófagos (cinco fagos, MOI 105), y almacenada a 21 °C por 24 y 72 h. Se realizaron recuentos bacterianos para evaluar la actividad biocontroladora de la mezcla y compararlos con un grupo contaminado, pero no tratado. Resultados: Se observaron reducciones significativas (hasta 3,75 log10 CFU/ml) en los grupos tratados con bacteriófagos (p<0,0001). Conclusiones: Estos resultados demuestran la efectividad del uso de bacteriófagos como agentes de biocontrol de Salmonella Enteritidis en un alimento crudo derivado del huevo. Sin embargo, se necesita realizar más estudios para comprobar la reducción en mayonesa casera no diluida.

Resumo Antecedentes: Salmonella enterica serovar Enteritidis (SE) é uma das principais causas de doenças transmitidas por alimentos em todo o mundo, principalmente associada ao consumo de produtos derivados de aves, como ovos. Diferentes métodos de controle foram implementados no processo de produção de ovos, mas não foram capazes de reduzir efetivamente os surtos nas pessoas. Por esse motivo, o uso de bacteriófagos para o controle biológico de patógenos de origem alimentar está ganhando crescente aceitação. Objetivo: Avaliar a eficácia de um coquetel de bacteriófagos na redução da contagem de SE em uma matriz experimentalmente semelhante a maionese contaminada. Método: A maionese caseira foi contaminada com SE (103 UFC/ml) no mesmo volume da matriz (1:1), tratada com uma mistura de bacteriófagos (cinco fagos, MOI 105) e armazenada a 21 °C por 24 e 72 h. As contagens bacterianas foram realizadas para avaliar a atividade de biocontrole da mistura e comparadas com um grupo contaminado, mas não tratado. Resultados: Reduções significativas (até 3,75 log10 UFC/ ml) foram observadas nos grupos tratados com bacteriófagos (p<0,0001). Conclusões: Esses resultados demonstram a eficácia do uso de bacteriófagos como agentes de biocontrole de Salmonella Enteritidis em alimentos crus derivados de ovos, mas são necessários mais estudos para verificar a redução da maionese caseira não diluída.

Biocontrol capability of bacteriophages against soft rot disease caused by Dickeya chrysanthemi

Aims@#This study aims to evaluate the effectiveness of bacteriophages isolated from Klang and Penang, Malaysia against Dickeya chrysanthemi that causes soft rot disease.@*Methodology and results@#Basic characterization such as dextrose test, citrate test, lactose fermentation test and ornithine test were carried out on D. chrysanthemi. Activity of bacteriophages against D. chrysanthemi was evaluated using spot test. Double agar overlay assay was performed to purify and enumerate the quantify of bacteriophages.Bacteriophages were also checked for its effectiveness in controlling soft rot on post-harvested vegetables: potato (Solanum tuberosum), cucumber (Cucumis sativus) and apple (Malus domestica). Results showed that D. chrysanthemiable to utilize citrate and dextrose as the source of energy, which indicated that D. chrysanthemi inclined to choose fruits and vegetables containing citrate and dextrose as the target of attack. Clear zone observed on the bacterial lawn (spot test) indicated the ability of the bacteriophages to infect and lyse D. chrysanthemi. All the bacteriophages studied herein reached the highest concentration on day 3 and were monovalent.@*Conclusion, significance and impact of study@#All the isolated bacteriophages were able to restrain the spreading of soft rot caused by D. chrysanthemi either work alone or as cocktail. This study provides information for the formulation development of bacteriophage against soft rot disease cause by D. chrysanthemi. Furthermore, this study reveals the potential of locally isolated bacteriophages against the D. chrysanthemi and paving the application of phage treatment on agriculture products that are not limited to potatoes, cucumber and apple.

Research progress on Streptococcus mutans phages in the prevention of dental caries / 口腔疾病防治

@#The Streptococcus mutans (S. mutans) phage, as one of the principal pathogenic bacteria of dental caries, is a main cause of the formation and development of dental caries due to its overproliferation in dental plaque biofilms. Bacterial viruses, also known as bacteriophages, have the capability of specifically infecting bacteria and effectively degrading bacterial biofilms. S. mutans phages, therefore, may prevent and control caries. Therapy based on phages has been applied in many fields, but the application of S. mutans phages in caries remains exploratory. This article will review the research progress of S. mutans phages in clinical caries prevention, aiming to provide a new idea for the clinical prevention of caries. The results of the literature review show that the living bacteriophage system has the advantages of high specificity, high affinity and good safety. However, due to its unstable structure, it can be processed into a more stable formulation by freeze-drying, spray drying, adding stability enhancers, or incorporating bacteriophages into ointments, biodegradable polymer matrices or particles to a certain extent to improve stability. The lysozyme produced by phages can digest the bacterial cell wall and release the assembled phage particles, which effectively cleave biofilms. In addition, the antigen binding fragment library for cariogenic pathogens was screened by phage display technology, and the purpose of caries prevention and treatment was achieved by passive immunization of antigen binding fragments. However, the host range of bacteriophages is narrow, so this kind of problem can be overcome by phage combined with traditional therapy or other drug use or cocktail therapy with multiple phages in clinical caries prevention and control.

Fagos de bactérias redutoras de sulfato em água de produção de um reservatório de petróleo offshore: método tentativo de concentração e purificação / Phages of Sulphate Reducing Bacteria in reactor water from offshore oil wells: tentative method for concentration and purification

RESUMO O controle do crescimento microbiano é um desafio crescente na produção de petróleo e gás, uma vez que a presença de determinadas bactérias traz impactos econômica e ambientalmente negativos. As bactérias redutoras de sulfato (BRS) são particularmente problemáticas, uma vez que são responsáveis pela corrosão biológica ligada à produção de sulfeto de hidrogênio, efeito conhecido como souring. A principal forma de controle das BRS atualmente é a injeção de biocidas, no entanto essa estratégia, além de requerer aplicação contínua, tem se revelado pouco efetiva na eliminação de biofilmes e é associada a um alto risco de contaminação das águas. Portanto, é necessário que se busquem abordagens mais eficientes e específicas em relação ao controle microbiológico. O uso de vírus bacteriófagos vem ao encontro dessas necessidades, pois eles, após se multiplicarem, geralmente provocam a lise celular, liberando novas partículas virais e evitando que a bactéria se prolifere. Diante disso, este estudo propõe estabelecer um método para a concentração e a determinação da eficiência de recuperação de bacteriófagos de BRS presentes em água de reator oriunda de poços de petróleo. As amostras foram coletadas de dois reatores operados em batelada alimentada e que simulam um poço de petróleo. As amostras de água de reator foram primeiramente clarificadas, os vírus eluídos desse sedimento e, em seguida, concentrados por ultracentrifugação. O concentrado viral foi então purificado com Vertrel XF. Ensaios de semeadura experimental de miofago P1 nas amostras de água do reator revelaram taxa de recuperação viral de 27,7%, contra ao 16% obtidos com outros protocolos.

ABSTRACT The control of microbial growth is an increasing challenge in the production of oil and gas, since the presence of certain bacteria has economic and environmental negative impacts. Sulphate reducing bacteria are particularly problematic, since they are responsible for the biological corrosion associated with the production of hydrogen sulfide, an effect known as souring. The main form of control is the use of biocides; however, this strategy, in addition to requiring continuous application, has proven to be ineffective in the elimination of biofilms and is associated with a high risk of water contamination. Therefore, it is necessary to seek more efficient and specific approaches to microbiological control. The use of bacteriophage viruses meets these needs, because after they multiply, they usually cause cell lysis, releasing new viral particles and preventing the bacteria from proliferating. In view of this, this study proposes to establish a method for the concentration and detection of bacteriophages of Sulphate Reducing Bacteria present in reactor water from oil wells. The samples were collected from two reactors, operated in a batch fed to simulate an oil well. The reactor water samples were first clarified, viruses adsorbed to sediment were eluted and then concentrated by ultracentrifugation. The viral concentrate was then purified with Vertrel-XF. Experimental seeding of P1 myophage in water samples from the reactor revealed a viral recovery rate of 27.7%, compared to the 16% obtained by use of other protocols.

Insights to the diphtheria toxin encoding prophages amongst clinical isolates of Corynebacterium diphtheriae from India

Diphtheria is a dreadful disease caused by Corynebacterium diphtheriae. Lysogenised bacteriophages carrying toxin gene in C. diphtheriae can make the strain toxigenic. However, such phage disseminates the toxin genes to other strains when it undergoes lytic phase. As little is known about the phage diversity in C. diphtheriae in India, the present study was undertaken to investigate the prophages integrated into the genome of 29 clinical isolates of C. diphtheriae using whole-genome shotgun sequencing. Amongst these isolates, 27 were toxigenic, while 2 were non-toxigenic strains. Of the 27 toxigenic strains, all harbored known phages carrying toxin gene and two other phages with unknown function. However, the two non-toxin strains did not harbour any of the phages in the genome. It is imperative to devise prevention strategies that hinder the dissemination of toxin by prophages, as it may increase the complications of diphtheria post-immunisation.

Productive infection and transduction by bacteriophage P1 in the species Salmonella bongori

Background: Horizontal gene transfer (HGT) is the most important mechanism in the evolution of new genetic capabilities in bacteria, including specific degradative pathways, virulence factors, and resistance to antibiotics. Among the processes involved in HGT, transduction is noteworthy. This is a mechanism for gene transmission mediated by a bacteriophage that functions both as a reservoir and as a vector of exogenous genes, which remain protected from environmental effects in the bacteriophage's capsid. Within this context, this investigation aimed to evaluate the ability of the generalized transducing bacteriophage P1 to productively infect and transduce in the bacterial species Salmonella bongori. Results: We could establish that a derivative of bacteriophage P1, P1Cm, infects strains of S. bongori with frequencies of lysogenization in the order of ~10−2 lysogens/UFP. Through thermal induction, infective viral progeny was obtained, and we could show that P1Cm readily formed plaques on S. bongori lawns, a phenomenon thus far not reported for other members of the genus Salmonella. Finally, we showed P1Cm-mediated transduction of the model plasmid RP4 at frequencies of ~10−7 transductants/donor. Conclusion: Therefore, bacteriophage P1 can be used as a tool for the genetic manipulation in the species S. bongori.

A study of efficacy of phage amplification technique in diagnosis of pulmonary and extra-pulmonary tuberculosis

Background: Tuberculosis (TB) is a leading infectious disease in India. Diagnosis of TB has always been a problem due to slow rate of growth of Mycobacterium tuberculosis. In this study, author had compared the conventional tools for diagnosis of TB with the new Fast Plaque TBTM.Methods: The study was conducted at Dr. ML Chest Hospital, Department of Tuberculosis and Respiratory Diseases, G.S.V.M. Medical College, Kanpur. Specimens were collected after taking informed consent from patients attending outpatient and indoor patients admitted in the hospital. Study consisted of cases having suspected tuberculous exudation both pulmonary and extra pulmonary.Results: Most of the patients in this study were between 21-40years of age. Most of them were male (78%). Most of the patients came from urban areas and middle socioeconomic strata. Among them 68% were smokers and 32% were non-smokers. Comparison of phage assay with clinical evidence of disease has been done and results were sensitivity 85.7%, specificity 100%, PPV 100%, NPV 84.6% found.Conclusions: Delay in diagnosis resulting in further delay to initiate drug therapy. In these circumstances the rapid detection of mycobacteria by phage amplification technique could lead to earlier institution of antitubercular treatment.

Screening and identification of polypeptides targeting hepatitis B virus HBP-TP protein / 中华微生物学和免疫学杂志

Objective To identify specific peptides binding to hepatitis B virus ( HBV) DNA pol-ymerase TP region ( HBP-TP) and to study their effects on HBV replication. -ethods The phage polypep-tide display library was screened using the HBP-TP recombinant protein expressed in Escherichia coli as a substrate to obtain the specific phage, the polypeptide region of which was then sequenced. Polypeptide se-quences with a repetition rate greater than 10％ were counted and commercially synthesized. Changes in HBV replication were detected after treatment of HBV-expressing cells with synthetic peptides as drugs. Re-sults Eight peptides targeting HBP-TP recombinant protein were screened out from the phage display librar-y. One of the peptides was found to have a significant inhibitory effect on HBV replication at cellular level. Conclusions A HBP-TP protein-targeting polypeptide with an inhibitory effect on HBV replication was ob-tained.

Specification of Bacteriophage Isolated Against Clinical Methicillin-Resistant Staphylococcus Aureus

OBJECTIVES: The emergence of resistant bacteria is being increasingly reported around the world, potentially threatening millions of lives. Amongst resistant bacteria, methicillin-resistant Staphylococcus aureus (MRSA) is the most challenging to treat. This is due to emergent MRSA strains and less effective traditional antibiotic therapies to Staphylococcal infections. The use of bacteriophages (phages) against MRSA is a new, potential alternate therapy. In this study, morphology, genetic and protein structure of lytic phages against MRSA have been analysed. METHODS: Isolation of livestock and sewage bacteriophages were performed using 0.4 μm membrane filters. Plaque assays were used to determine phage quantification by double layer agar method. Pure plaques were then amplified for further characterization. Sulfate-polyacrylamide gel electrophoresis and random amplification of polymorphic DNA were run for protein evaluation, and genotyping respectively. Transmission electron microscope was also used to detect the structure and taxonomic classification of phage visually. RESULTS: Head and tail morphology of bacteriophages against MRSA were identified by transmission electron microscopy and assigned to the Siphoviridae family and the Caudovirales order. CONCLUSION: Bacteriophages are the most abundant microorganism on Earth and coexist with the bacterial population. They can destroy bacterial cells successfully and effectively. They cannot enter mammalian cells which saves the eukaryotic cells from lytic phage activity. In conclusion, phage therapy may have many potential applications in microbiology and human medicine with no side effect on eukaryotic cells.

Isolation, biological characteristics and genomic safety assessment of drug-resistant Klebsiella pneumoniae phage JD902 / 上海交通大学学报（医学版）

Objective • To screen for a bacteriophage of a drug-resistant Klebsiella pneumoniae strain and assess its eligibility to be incorporated into the Klebsiella bacteriophage library. Methods • A drug-resistant Klebsiella pneumoniae strain isolated from a patient with urinary infection was used as the host strain. Phage screening was carried out in environmental sewage, and the bacteriophage was isolated, purified, characterized and sequenced. Safety evaluation was also conducted based on the genome sequence. Results • A drug-resistant Klebsiella pneumoniae bacteriophage was isolated and designated as JD902, which belonged to Caudovirales. The burst size was 88 pfu/cell, and it could maintain good activity in pH range 4.0-11.0. Genomic analysis demonstrated that it did not carry any antibiotic resistance genes and virulence factor genes. Conclusion • JD902 is a virulent phage with high stability and safety in vitro. It can be incorporated into bacteriophage library for clinical treatment.

Encapsulation of specific Salmonella Enteritidis phage f3αSE on alginate-spheres as a method for protection and dosification

Background: Bacteriophages have been proposed as an alternative to control pathogenic bacteria resistant to antibiotics. However, they are not extensively used due to different factors such as vulnerability under environmental conditions and the lack of efficient administration methods. A potential solution is the encapsulation of bacteriophages in hydrogel polymers to increase their viability and as a controlled release method. This work describes the use of alginate-Ca+2 matrixes as mechanisms for protection and dosification of the phage f3αSE which has been successfully used to prevent infections produced by Salmonella Enteritidis. Results: The viability of the pure phage is reduced in near 100% after 1-h incubation at pH 2 or 3. However, the encapsulated phage remains active in 80, 6% at pH 3, while no differences were observed at pH 2, 4 or 7. Exposition of f3αSE to different T° showed that the viability of this phage decreased with increased T° to near 15% at 60°C, while the encapsulated phage remains with 50% viability at same temperature. Finally, the encapsulation of phages showed to extend their presence for 100 h in the medium compared to non-encapsulated phages in a water flow system, which simulate automatic birdbath used in poultry industry, maintaining the phage concentration between 102 and 104 PFU/mL during 250 h. Conclusions: Encapsulation in alginate-Ca+2 spheres can be a good alternative to extend viability of phages and can be used as a phage method dosification method in water flow systems.