Comparative physiological study of the wild type and the small colony variant of Pseudomonas aeruginosa 20265 under controlled growth conditions

2013 ◽  
Vol 30 (3) ◽  
pp. 1027-1036 ◽  
Author(s):  
W. Sabra ◽  
A. M. Haddad ◽  
A.-P. Zeng
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Growth Conditions ◽  
Physiological Study ◽  
Controlled Growth ◽  
Wild Type ◽  
Small Colony Variant ◽  
Small Colony

scholarly journals Expression Analysis of a Highly Adherent and Cytotoxic Small Colony Variant of Pseudomonas aeruginosa Isolated from a Lung of a Patient with Cystic Fibrosis

2004 ◽  
Vol 186 (12) ◽  
pp. 3837-3847 ◽  
Author(s):  
Franz von Götz ◽  
Susanne Häussler ◽  
Doris Jordan ◽  
Senthil Selvan Saravanamuthu ◽  
Dirk Wehmhöner ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Dna Microarrays ◽  
Effector Proteins ◽  
Wild Type ◽  
Small Colony Variant ◽  
A Genome ◽  
Small Colony ◽  
Type Iii Protein Secretion

ABSTRACT The heterogeneous environment of the lung of the cystic fibrosis (CF) patient gives rise to Pseudomonas aeruginosa small colony variants (SCVs) with increased antibiotic resistance, autoaggregative growth behavior, and an enhanced ability to form biofilms. In this study, oligonucleotide DNA microarrays were used to perform a genome-wide expression study of autoaggregative and highly adherent P. aeruginosa SCV 20265 isolated from a CF patient's lung in comparison with its clonal wild type and a revertant generated in vitro from the SCV population. Most strikingly, SCV 20265 showed a pronounced upregulation of the type III protein secretion system (TTSS) and the respective effector proteins. This differential expression was shown to be biologically meaningful, as SCV 20265 and other hyperpiliated and autoaggregative SCVs with increased TTSS expression were significantly more cytotoxic for macrophages in vitro and were more virulent in a mouse model of respiratory tract infection than the wild type. The observed cytotoxicity and virulence of SCV 20265 required exsA, an important transcriptional activator of the TTSS. Thus, the prevailing assumption that P. aeruginosa is subject to selection towards reduced cytotoxicity and attenuated virulence during chronic CF lung infection might not apply to all clonal variants.

scholarly journals Enhanced production of exopolysaccharide matrix and biofilm by a menadione-auxotrophic Staphylococcus aureus small-colony variant

2010 ◽  
Vol 59 (5) ◽  
pp. 521-527 ◽  
Author(s):  
Rachna Singh ◽  
Pallab Ray ◽  
Anindita Das ◽  
Meera Sharma
Keyword(s):  
Staphylococcus Aureus ◽  
Tricarboxylic Acid Cycle ◽  
Surface Hydrophobicity ◽  
Tricarboxylic Acid ◽  
Polysaccharide Intercellular Adhesin ◽  
Wild Type ◽  
Small Colony Variant ◽  
Enhanced Production ◽  
Small Colony

The role of Staphylococcus aureus small-colony variants (SCVs) in the pathogenesis of biofilm-associated infections remains unclear. This study investigated the mechanism behind increased biofilm-forming potential of a menadione-auxotrophic Staphylococcus aureus SCV compared with the wild-type parental strain, as recently reported by our laboratory. SCVs displayed an autoaggregative phenotype, with a greater amount of polysaccharide intercellular adhesin (PIA), significantly reduced tricarboxylic acid cycle activity and a decreased susceptibility to aminoglycosides and cell-wall inhibitors compared with wild-type. The biofilms formed by the SCV were highly structured, consisting of large microcolonies separated by channels, and contained more biomass as well as significantly more PIA than wild-type biofilms. The surface hydrophobicity of the two phenotypes was similar. Thus, the autoaggregation and increased biofilm-forming capacity of menadione-auxotrophic Staphylococcus aureus SCVs in this study was related to the enhanced production of PIA in these variants.

scholarly journals Pseudomonas aeruginosa Rugose Small-Colony Variants Have Adaptations That Likely Promote Persistence in the Cystic Fibrosis Lung

2009 ◽  
Vol 191 (11) ◽  
pp. 3492-3503 ◽  
Author(s):  
Melissa Starkey ◽  
Jason H. Hickman ◽  
Luyan Ma ◽  
Niu Zhang ◽  
Susan De Long ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Intracellular Signaling ◽  
Tricarboxylic Acid Cycle ◽  
Gene Clusters ◽  
Wild Type ◽  
Phenotypic Analysis ◽  
Small Colony Variants ◽  
Airway Infections ◽  
Small Colony

ABSTRACT Pseudomonas aeruginosa is recognized for its ability to colonize diverse habitats, ranging from soil to immunocompromised people. The formation of surface-associated communities called biofilms is one factor thought to enhance colonization and persistence in these diverse environments. Another factor is the ability of P. aeruginosa to diversify genetically, generating phenotypically distinct subpopulations. One manifestation of diversification is the appearance of colony morphology variants on solid medium. Both laboratory biofilm growth and chronic cystic fibrosis (CF) airway infections produce rugose small-colony variants (RSCVs) characterized by wrinkled, small colonies and an elevated capacity to form biofilms. Previous reports vary on the characteristics attributable to RSCVs. Here we report a detailed comparison of clonally related wild-type and RSCV strains isolated from both CF sputum and laboratory biofilm cultures. The clinical RSCV had many characteristics in common with biofilm RSCVs. Transcriptional profiling and Biolog phenotypic analysis revealed that RSCVs display increased expression of the pel and psl polysaccharide gene clusters, decreased expression of motility functions, and a defect in growth on some amino acid and tricarboxylic acid cycle intermediates as sole carbon sources. RSCVs also elicited a reduced chemokine response from polarized airway epithelium cells compared to wild-type strains. A common feature of all RSCVs analyzed in this study is increased levels of the intracellular signaling molecule cyclic di-GMP (c-di-GMP). To assess the global transcriptional effects of elevated c-di-GMP levels, we engineered an RSCV strain that had elevated c-di-GMP levels but did not autoaggregate. Our results showed that about 50 genes are differentially expressed in response to elevated intracellular c-di-GMP levels. Among these genes are the pel and psl genes, which are upregulated, and flagellum and pilus genes, which are downregulated. RSCV traits such as increased exopolysaccharide production leading to antibiotic tolerance, altered metabolism, and reduced immunogenicity may contribute to increased persistence in biofilms and in the airways of CF lungs.

scholarly journals Rapidly Correcting Frameshift Mutations in the Mycobacterium tuberculosis orn Gene Produce Reversible Ethambutol Resistance and Small-Colony-Variant Morphology

2020 ◽  
Vol 64 (9) ◽  
Author(s):  
Hassan Safi ◽  
Subramanya Lingaraju ◽  
Shuyi Ma ◽  
Seema Husain ◽  
Mainul Hoque ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Frameshift Mutation ◽  
Relative Increase ◽  
Wild Type ◽  
Content Type ◽  
Reading Frame ◽  
Small Colony Variant ◽  
Large Colony ◽  
Small Colony ◽  
High Level

ABSTRACT We have identified a previously unknown mechanism of reversible high-level ethambutol (EMB) resistance in Mycobacterium tuberculosis that is caused by a reversible frameshift mutation in the M. tuberculosis orn gene. A frameshift mutation in orn produces the small-colony-variant (SCV) phenotype, but this mutation does not change the MICs of any drug for wild-type M. tuberculosis. However, the same orn mutation in a low-level EMB-resistant double embB-aftA mutant (MIC = 8 μg/ml) produces an SCV with an EMB MIC of 32 μg/ml. Reversible resistance is indistinguishable from a drug-persistent phenotype, because further culture of these orn-embB-aftA SCV mutants results in rapid reversion of the orn frameshifts, reestablishing the correct orn open reading frame, returning the culture to normal colony size, and reversing the EMB MIC back to that (8 μg/ml) of the parental strain. Transcriptomic analysis of orn-embB-aftA mutants compared to wild-type M. tuberculosis identified a 27-fold relative increase in the expression of embC, which is a cellular target for EMB. Expression of embC in orn-embB-aftA mutants was also increased 5-fold compared to that in the parental embB-aftA mutant, whereas large-colony orn frameshift revertants of the orn-embB-aftA mutant had levels of embC expression similar to that of the parental embB-aftA strain. Reversible frameshift mutants may contribute to a reversible form of microbiological drug resistance in human tuberculosis.

scholarly journals Influence of the Protein Kinase C Activator Phorbol Myristate Acetate on the Intracellular Activity of Antibiotics against Hemin- and Menadione-Auxotrophic Small-Colony Variant Mutants of Staphylococcus aureus and Their Wild-Type Parental Strain in Human THP-1 Cells

2012 ◽  
Vol 56 (12) ◽  
pp. 6166-6174 ◽  
Author(s):  
Laetitia G. Garcia ◽  
Sandrine Lemaire ◽  
Barbara C. Kahl ◽  
Karsten Becker ◽  
Richard A. Proctor ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Parental Strain ◽  
Wild Type ◽  
Content Type ◽  
Small Colony Variant ◽  
Intracellular Activity ◽  
Kinase C ◽  
Pharmacodynamic Profile ◽  
Small Colony ◽  
Intracellular Fate

ABSTRACTIn a previous study (L. G. Garcia et al., Antimicrob. Agents Chemother. 56:3700–3711, 2012), we evaluated the intracellular fate ofmenDandhemBmutants (corresponding to menadione- and hemin-dependent small-colony variants, respectively) of the parental COL methicillin-resistantStaphylococcus aureusstrain and the pharmacodynamic profile of the intracellular activity of a series of antibiotics in human THP-1 monocytes. We have now examined the phagocytosis and intracellular persistence of the same strains in THP-1 cells activated by phorbol 12-myristate 13-acetate (PMA) and measured the intracellular activity of gentamicin, moxifloxacin, and oritavancin in these cells. Postphagocytosis intracellular counts and intracellular survival were lower in PMA-activated cells, probably due to their higher killing capacities. Gentamicin and moxifloxacin showed a 5- to 7-fold higher potency (lower static concentrations) against the parental strain, itshemBmutant, and the genetically complemented strain in PMA-activated cells and against themenDstrain in both activated and nonactivated cells. This effect was inhibited when cells were incubated withN-acetylcysteine (a scavenger of oxidant species). In parallel, we observed that the MICs of these drugs were markedly reduced if bacteria had been preexposed to H2O2. In contrast, the intracellular potency of oritavancin was not different in activated and nonactivated cells and was not decreased by the addition ofN-acetylcysteine, regardless of the phenotype of the strains. The oritavancin MIC was also unaffected by preincubation of the bacteria with H2O2. Thus, activation of THP-1 cells by PMA may increase the intracellular potency of certain antibiotics (probably due to synergy with reactive oxygen species), but this effect cannot be generalized to all antibiotics.

scholarly journals Adaptation Genomics of a Small-Colony Variant in a Pseudomonas chlororaphis 30-84 Biofilm

2014 ◽  
Vol 81 (3) ◽  
pp. 890-899 ◽  
Author(s):  
Dongping Wang ◽  
Robert J. Dorosky ◽  
Cliff S. Han ◽  
Chien-chi Lo ◽  
Armand E. K. Dichosa ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Genetic Alterations ◽  
Whole Genome Sequence ◽  
Phenotypic Switching ◽  
Whole Genome ◽  
Pseudomonas Chlororaphis ◽  
Wild Type ◽  
Content Type ◽  
Small Colony Variant ◽  
Small Colony

ABSTRACTThe rhizosphere-colonizing bacteriumPseudomonas chlororaphis30-84 is an effective biological control agent against take-all disease of wheat. In this study, we characterize a small-colony variant (SCV) isolated from aP. chlororaphis30-84 biofilm. The SCV exhibited pleiotropic phenotypes, including small cell size, slow growth and motility, low levels of phenazine production, and increased biofilm formation and resistance to antimicrobials. To better understand the genetic alterations underlying these phenotypes, RNA and whole-genome sequencing analyses were conducted comparing an SCV to the wild-type strain. Of the genome's 5,971 genes, transcriptomic profiling indicated that 1,098 (18.4%) have undergone substantial reprograming of gene expression in the SCV. Whole-genome sequence analysis revealed multiple alterations in the SCV, including mutations inyfiR(cyclic-di-GMP production),fusA(elongation factor), andcyoE(heme synthesis) and a 70-kb deletion. Genetic analysis revealed that theyfiRlocus plays a major role in controlling SCV phenotypes, including colony size, growth, motility, and biofilm formation. Moreover, a point mutation in thefusAgene contributed to kanamycin resistance. Interestingly, the SCV can partially switch back to wild-type morphologies under specific conditions. Our data also support the idea that phenotypic switching inP. chlororaphisis not due to simple genetic reversions but may involve multiple secondary mutations. The emergence of these highly adherent and antibiotic-resistant SCVs within the biofilm might play key roles inP. chlororaphisnatural persistence.

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