scholarly journals Disentangling bacterial invasiveness from lethality in an experimental host-pathogen system

2018 ◽  
Author(s):  
Tommaso Biancalani ◽  
Jeff Gore
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Mortality Rate ◽  
Serratia Marcescens ◽  
Salmonella Enterica ◽  
Disease Ecology ◽  
Evolutionary Biology ◽  
Host Population ◽  
Infection Process ◽  
Laboratory Population ◽  
Treatment And Prevention

ABSTRACTQuantifying virulence remains a central problem in human health, pest control, disease ecology, and evolutionary biology. Bacterial virulence is typically quantified by theLT50(i.e.the time taken to kill 50% of infected hosts), however, such an indicator cannot account for the full complexity of the infection process, such as distinguishing between the pathogen’s ability to colonize vs. kill the hosts. Indeed, the pathogen needs to breach the primary defenses in order to colonize, find a suitable environment to replicate, and finally express the virulence factors that cause disease. Here, we show that two virulence attributes, namely pathogen lethality and invasiveness, can be disentangled from the survival curves of a laboratory population ofCaenorhabditis elegansnematodes exposed to three bacterial pathogens:Pseudomonas aeruginosa,Serratia marcescensandSalmonella enterica. We first show that the host population eventually experiences a constant mortality rate, which quantifies the lethality of the pathogen. We then show that the time necessary to reach this constant-mortality rate regime depends on the pathogen growth rate and colonization rate, and thus determines the pathogen invasiveness. Our framework reveals thatSerratia marcescensis particularly good at the initial colonization of the host, whereasSalmonella entericais a poor colonizer yet just as lethal once established.Pseudomonas aeruginosa, on the other hand, is both a good colonizer and highly lethal after becoming established. The ability to quantitatively characterize the ability of different pathogens to perform each of these steps has implications for treatment and prevention of disease and for the evolution and ecology of pathogens.

scholarly journals Application strategies by selective medium treated with entomopathogenic bacteria Serratia marcescens and Pseudomonas aeruginosa as potential biocontrol against Coptotermes curvignathus

2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Kit Ling Chin ◽  
Paik San H'ng ◽  
Chuan Li Lee ◽  
Wan Zhen Wong ◽  
Wen Ze Go ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Mortality Rate ◽  
Serratia Marcescens ◽  
Selective Medium ◽  
Subterranean Termite ◽  
High Toxicity ◽  
Entomopathogenic Bacteria ◽  
Long Period ◽  
Behaviour Changes ◽  
Wood Consumption

The success of microbial termiticides in controlling termites depends on the ability of microbes to grow in different media and the functionality of the microbes as a resistant barrier or toxic bait. This study was conducted to understand the mortality rate and behaviour changes of the subterranean termite Coptotermes curvignathus Holmgren introduced with different concentrations of Serratia marcescens strain LGMS 1 and Pseudomonas aeruginosa strain LGMS 3 using wood and soil as bacterial transfer medium. In general, higher concentration of bacteria in soil caused a reduction in tunnelling activity and wood consumption and an increase in mortality. However, application on wood revealed a different outcome. Wood treated with S. marcescens of 10 6 CFU ml −1 concentration proved to be more efficient as bait than higher concentration applications as it caused a high mortality rate while still highly palatable for termites. Wood or soil treated with S. marcescens concentration higher than 10 9 CFU ml −1 creates a high toxicity and repellent barrier for termites. Pseudomonas aeruginosa of 10 9 CFU ml −1 concentrations applied on wood served as a slow-acting toxic bait. However, the ability for S. marcescens and P. aeruginosa to survive on wood is low, which made the bait unable to retain a useful level of toxicity for a long period of time and frequent reapplication is needed.

Pertussis

2018 ◽  
Keyword(s):  
Public Health ◽  
Disease Ecology ◽  
Evolutionary Biology ◽  
Expert Knowledge ◽  
Whooping Cough ◽  
Vaccine Coverage ◽  
The United States ◽  
Vaccine Preventable Diseases ◽  
Treatment And Prevention ◽  
Evolutionary Epidemiology

Pertussis, or whooping cough, is a respiratory disease caused primarily by infection with the bacterium Bordetella pertussis. It remains one of the leading causes of death among vaccine-preventable diseases worldwide and recent years have seen its alarming re-emergence in many regions (including the United States and much of Europe), despite sustained high levels of vaccine coverage. The causes of the resurgence remain contentious, in part due to inherent complexities of the pathogen’s biology, in part due to pronounced variation in the treatment and prevention strategies between different countries and regions, and in part due to long-standing disagreement among scientific researchers studying pertussis. This edited volume brings together expert knowledge from disparate fields with the overall aim of synthesizing the current understanding of this critically important, global pathogen. Pertussis: Epidemiology, Immunology, and Evolution is an advanced text suitable for graduate-level students taking courses in evolutionary epidemiology, disease ecology, and evolutionary biology, as well as academics, public health officials, and researchers in these fields. It also offers a very useful introduction to a wider audience of public health practitioners, microbiologists, epidemiologists, medical professionals, and vaccine biologists

scholarly journals Effects of heterogeneity in infection-exposure history and immunity on the dynamics of a protozoan parasite

2007 ◽  
Vol 4 (16) ◽  
pp. 841-849 ◽  
Author(s):  
Maite Severins ◽  
Don Klinkenberg ◽  
Hans Heesterbeek
Keyword(s):  
Dynamic Behaviour ◽  
Protozoan Parasite ◽  
Host Population ◽  
Infection Process ◽  
Control Measures ◽  
Complex Dynamic ◽  
Systems Models ◽  
Exposure History ◽  
The Relationship ◽  
Initial Contamination

Infection systems where traits of the host, such as acquired immunity, interact with the infection process can show complex dynamic behaviour with counter-intuitive results. In this study, we consider the traits ‘immune status’ and ‘exposure history’, and our aim is to assess the influence of acquired individual heterogeneity in these traits. We have built an individual-based model of Eimeria acervulina infections, a protozoan parasite with an environmental stage that causes coccidiosis in chickens. With the model, we simulate outbreaks of the disease under varying initial contaminations. Heterogeneity in the traits arises stochastically through differences in the dose and frequency of parasites that individuals pick up from the environment. We find that the relationship between the initial contamination and the severity of an outbreak has a non-monotonous ‘wave-like’ pattern. This pattern can be explained by an increased heterogeneity in the host population caused by the infection process at the most severe outbreaks. We conclude that when dealing with these types of infection systems, models that are used to develop or evaluate control measures cannot neglect acquired heterogeneity in the host population traits that interact with the infection process.

THE POTENTIAL OF BACTERIA FOR THE MICROBIAL CONTROL OF GRASSHOPPERS AND LOCUSTS

1997 ◽  
Vol 129 (S171) ◽  
pp. 147-156 ◽  
Author(s):  
B. Zelazny ◽  
M.S. Goettel ◽  
B. Keller
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacillus Thuringiensis ◽  
Serratia Marcescens ◽  
Schistocerca Gregaria ◽  
Locusta Migratoria ◽  
Microbial Control ◽  
Control Agent ◽  
Promising Agent ◽  
Laboratory Populations ◽  
The Many

AbstractBacteria have been implicated in disease epizootics observed in field populations and laboratory-reared locusts and grasshoppers. Two species [Serratia marcescens Bizio and Pseudomonas aeruginosa (Schroeter) Migula] consistently infect locusts when ingested with food and can spread in laboratory populations. However, research on developing these organisms for microbial control of locusts and grasshoppers begun in the 1950s has not been continued. In recent years strains of Bacillus thuringiensis Berliner have been studied for activity against locusts and grasshoppers. Results of additional trials by the authors are reported. Among 393 B. thuringiensis isolates and 93 preparations of other sporeforming bacteria fed to nymphs of Locusta migratoria (L.) and/or Schistocerca gregaria Forsk., none has shown any pathogenicity to the insects. The recent discovery of novel B. thuringiensis strains active against various diverse pests and the many properties of a sporeforming bacterium that satisfy the requirements for a microbial control agent, and the development of Serratia entomophila as a promising agent for control of grass grubs, provide incentive to continue the search for an orthopteran-active sporeforming bacterium and to re-investigate the potential of non-sporeforming bacterial pathogens as microbial control agents of grasshoppers and locusts.

scholarly journals OS PRINCIPAIS FATORES DE RISCO DA PNEUMONIA ASSOCIADA À VENTILAÇÃO MECÂNICA EM UTI ADULTA.

2016 ◽  
Vol 7 (1) ◽  
pp. 80-92
Author(s):  
Janice Barbieri Costa ◽  
Alessandro Alessandro Lima Costa Lima ◽  
Fernanda Torres ◽  
Antônia de Fátima Galdino da Silva ◽  
André Tomaz Terra Júnior
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Serratia Marcescens ◽  
Terapia Intensiva

A pneumonia é uma inflamação do parênquima pulmonar causada por diversos agentes etiológicos, as pneumonias hospitalares são causadas principalmente por Enterobacter, Escherichia coli, Klebsiella, Proteus, Serratia marcescens, Pseudomonas aeruginosa e Staphylococcus aureus. A pneumonia associada à ventilação mecânica (PAVM) é considerada a infecção nosocomial mais frequente em unidades de terapia intensiva (UTI) e é definida como uma inflamação do parênquima pulmonar, que aparece após 48 a 72 horas da intubação endotraqueal e do inicio da ventilação mecânica. O objetivo desse trabalho foi demonstrar os principais fatores de risco para a aquisição da PAVM. A pesquisa de revisão literária se deu através de base de dados, como PubMed e Bireme, LILACS, SciELO, o período de publicação compreenderam os anos de 1998 á 2013. A PAVM possui alguns fatores de risco, que são classificados em modificáveis ou não modificáveis.  Alguns exemplos desses fatores de risco não modificáveis são: idade, gravidade da doença de base, Doença Pulmonar Obstrutiva Crônica (DPOC). E os fatores modificáveis alguns exemplos são: educação continuada dos profissionais sobre os fatores de risco, o estabelecimento de protocolos que evitem o uso indiscriminado de antibióticos. Conclui-se através dessa revisão literária que a maioria dos pacientes internados em UTI está em ventilação mecânica (VM) e que nos pacientes intubados, a incidência de pneumonia é de 7 a 21 vezes mais elevado em relação àqueles que não necessitam de ventiladores e por isso são necessárias medidas preventivas.

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