Limits...
Phenotypic and Genotypic Characteristics of Small Colony Variants and Their Role in Chronic Infection.

Johns BE, Purdy KJ, Tucker NP, Maddocks SE - Microbiol Insights (2015)

Bottom Line: They display unique phenotypic characteristics conferred in part by heritable genetic changes.Characteristically slow growing, SCVs comprise a minor proportion of the population from which they arise but persist by virtue of their inherent resilience and host adaptability.This review discusses some of the phenotypic and genotypic changes that enable SCVs to successfully proliferate within the host environment as potential pathogens and strategies that could ameliorate the resolution of infection where SCVs are present.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Science, Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK.

ABSTRACT
Small colony variant (SCV) bacteria arise spontaneously within apparently homogeneous microbial populations, largely in response to environmental stresses, such as antimicrobial treatment. They display unique phenotypic characteristics conferred in part by heritable genetic changes. Characteristically slow growing, SCVs comprise a minor proportion of the population from which they arise but persist by virtue of their inherent resilience and host adaptability. Consequently, SCVs are problematic in chronic infection, where antimicrobial treatment is administered during the acute phase of infection but fails to eradicate SCVs, which remain within the host causing recurrent or chronic infection. This review discusses some of the phenotypic and genotypic changes that enable SCVs to successfully proliferate within the host environment as potential pathogens and strategies that could ameliorate the resolution of infection where SCVs are present.

No MeSH data available.


Related in: MedlinePlus

WT organisms undergo a shift to the SCV phenotype under the conditions of stress, where they exhibit a slower growth rate but increased antibiotic resistance. They can revert to a WT-like (indicated by a dashed line to denote that WT-like organisms are not identical to the original WT progenitor) or alternative revertant (R) phenotype when the environmental stress is removed, regaining a faster growth rate but becoming more susceptible to antibiotic treatment.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4581789&req=5

f1-mbi-8-2015-015: WT organisms undergo a shift to the SCV phenotype under the conditions of stress, where they exhibit a slower growth rate but increased antibiotic resistance. They can revert to a WT-like (indicated by a dashed line to denote that WT-like organisms are not identical to the original WT progenitor) or alternative revertant (R) phenotype when the environmental stress is removed, regaining a faster growth rate but becoming more susceptible to antibiotic treatment.

Mentions: Early studies clarified the link between environmental stress and the phenotypic changes that became associated with SCVs, including atypical colony morphology, slow growth rate, lack of pigmentation, reduced hemolytic activity, reduced coagulase activity, reduced carbohydrate utilization, low virulence potential, and elevated antibiotic resistance (Fig. 1).7–9 Indeed, the growth rate of SCVs has been estimated to be approximately nine times slower than that of the progenitor organisms.10 As such, SCVs are now better defined as a microbial subpopulation constituting a naturally occurring, slow-growing but diverse bacterial morphotype.7,11 Clinically, this is problematic; the presence of SCVs during infection is correlated with recurrent or chronic infectious disease. A combination of extended incubation time in addition to altered phenotypic and biochemical traits often means that SCVs in patient samples are overlooked by clinical microbiologists utilizing conventional diagnostic tests. This results in the cessation of antimicrobial treatment before SCVs are effectively cleared from an infection; therefore, they persist causing recurrent and chronic infection.7,12


Phenotypic and Genotypic Characteristics of Small Colony Variants and Their Role in Chronic Infection.

Johns BE, Purdy KJ, Tucker NP, Maddocks SE - Microbiol Insights (2015)

WT organisms undergo a shift to the SCV phenotype under the conditions of stress, where they exhibit a slower growth rate but increased antibiotic resistance. They can revert to a WT-like (indicated by a dashed line to denote that WT-like organisms are not identical to the original WT progenitor) or alternative revertant (R) phenotype when the environmental stress is removed, regaining a faster growth rate but becoming more susceptible to antibiotic treatment.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4581789&req=5

f1-mbi-8-2015-015: WT organisms undergo a shift to the SCV phenotype under the conditions of stress, where they exhibit a slower growth rate but increased antibiotic resistance. They can revert to a WT-like (indicated by a dashed line to denote that WT-like organisms are not identical to the original WT progenitor) or alternative revertant (R) phenotype when the environmental stress is removed, regaining a faster growth rate but becoming more susceptible to antibiotic treatment.
Mentions: Early studies clarified the link between environmental stress and the phenotypic changes that became associated with SCVs, including atypical colony morphology, slow growth rate, lack of pigmentation, reduced hemolytic activity, reduced coagulase activity, reduced carbohydrate utilization, low virulence potential, and elevated antibiotic resistance (Fig. 1).7–9 Indeed, the growth rate of SCVs has been estimated to be approximately nine times slower than that of the progenitor organisms.10 As such, SCVs are now better defined as a microbial subpopulation constituting a naturally occurring, slow-growing but diverse bacterial morphotype.7,11 Clinically, this is problematic; the presence of SCVs during infection is correlated with recurrent or chronic infectious disease. A combination of extended incubation time in addition to altered phenotypic and biochemical traits often means that SCVs in patient samples are overlooked by clinical microbiologists utilizing conventional diagnostic tests. This results in the cessation of antimicrobial treatment before SCVs are effectively cleared from an infection; therefore, they persist causing recurrent and chronic infection.7,12

Bottom Line: They display unique phenotypic characteristics conferred in part by heritable genetic changes.Characteristically slow growing, SCVs comprise a minor proportion of the population from which they arise but persist by virtue of their inherent resilience and host adaptability.This review discusses some of the phenotypic and genotypic changes that enable SCVs to successfully proliferate within the host environment as potential pathogens and strategies that could ameliorate the resolution of infection where SCVs are present.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Science, Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK.

ABSTRACT
Small colony variant (SCV) bacteria arise spontaneously within apparently homogeneous microbial populations, largely in response to environmental stresses, such as antimicrobial treatment. They display unique phenotypic characteristics conferred in part by heritable genetic changes. Characteristically slow growing, SCVs comprise a minor proportion of the population from which they arise but persist by virtue of their inherent resilience and host adaptability. Consequently, SCVs are problematic in chronic infection, where antimicrobial treatment is administered during the acute phase of infection but fails to eradicate SCVs, which remain within the host causing recurrent or chronic infection. This review discusses some of the phenotypic and genotypic changes that enable SCVs to successfully proliferate within the host environment as potential pathogens and strategies that could ameliorate the resolution of infection where SCVs are present.

No MeSH data available.


Related in: MedlinePlus