The Small Colony Variant of Listeria monocytogenes Is More Tolerant to Antibiotics and Has Altered Survival in RAW 264.7 Murine Macrophages

Curtis, Thomas; Gram, Lone; Knudsen, Gitte M.

doi:10.3389/fmicb.2016.01056

Cited by 19 publications

(13 citation statements)

References 59 publications

(83 reference statements)

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“…Likewise, investigations with Bacillales SCVs showed that TO efficiently killed S. aureus , B. cereus and B. subtillis but not L. monocytogenes SCVs despite its very low MIC and TO was thus bacteriostatic against that species. L. monocytogenes SCVs are indeed quite tolerant to the bactericidal effects of many classes of antibacterial agents [ 35 ]. Therefore, amelioration of the bactericidal activity of TO against this important pathogen, as seen with its derivative FC04–100, is an important breakthrough.…”

Section: Discussionmentioning

confidence: 99%

Tomatidine and analog FC04–100 possess bactericidal activities against Listeria, Bacillus and Staphylococcus spp

Guay

Boulanger

Isabelle

et al. 2018

BMC Pharmacol Toxicol

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BackgroundTomatidine (TO) is a plant steroidal alkaloid that possesses an antibacterial activity against the small colony variants (SCVs) of Staphylococcus aureus. We report here the spectrum of activity of TO against other species of the Bacillales and the improved antibacterial activity of a chemically-modified TO derivative (FC04–100) against Listeria monocytogenes and antibiotic multi-resistant S. aureus (MRSA), two notoriously difficult-to-kill microorganisms.MethodsBacillus and Listeria SCVs were isolated using a gentamicin selection pressure. Minimal inhibitory concentrations (MICs) of TO and FC04–100 were determined by a broth microdilution technique. The bactericidal activity of TO and FC04–100 used alone or in combination with an aminoglycoside against planktonic bacteria was determined in broth or against bacteria embedded in pre-formed biofilms by using the Calgary Biofilm Device. Killing of intracellular SCVs was determined in a model with polarized pulmonary cells.ResultsTO showed a bactericidal activity against SCVs of Staphylococcus aureus, Bacillus cereus, B. subtilis and Listeria monocytogenes with MICs of 0.03–0.12 μg/mL. The combination of an aminoglycoside and TO generated an antibacterial synergy against their normal phenotype. In contrast to TO, which has no relevant activity by itself against Bacillales of the normal phenotype (MIC > 64 μg/mL), the TO analog FC04–100 showed a MIC of 8–32 μg/mL. Furthermore, FC04–100 showed a strong bactericidal activity against L. monocytogenes SCVs in kill kinetics experiments, while TO did not. The addition of FC04–100 (4 μg/mL) to a cefalexin:kanamycin (3:2) combination improved the activity of the combination by 32 fold against cefalexin and kanamycin-resistant MRSA strains. In combination with gentamicin, FC04–100 also exhibited a strong bactericidal activity against biofilm-embedded S. aureus. Also, FC04–100 and TO showed comparable intracellular killing of S. aureus SCVs.ConclusionsChemical modifications of TO allowed improvement of its antibacterial activity against prototypical S. aureus and of its bactericidal activity against L. monocytogenes. Antibacterial activities against such prominent pathogens could be useful to prevent Listeria contamination in the food chain or as treatment for MRSA infections.

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Section: Discussionmentioning

confidence: 99%

Tomatidine and analog FC04–100 possess bactericidal activities against Listeria, Bacillus and Staphylococcus spp

Guay

Boulanger

Isabelle

et al. 2018

BMC Pharmacol Toxicol

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“…coli 10129 LB_2, suggesting that the novel SNP in hemA influences resistance to gentamicin. Previous SNPs in hemA resulting in the SCV phenotype have been identified, which resulted in amino acid changes at position valine-45-glycine [3, 13], serine-232-stop [3, 13] and glutamine-225-stop [14, 15], with the latter two resulting in an early termination of the protein. The SNP we identified in this E.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…HemA is a glutamyl-tRNA reductase that catalyses the initial step of porphyrin biosynthesis leading to the production of haem, which is required for respiration. Single nucleotide polymorphisms (SNPs) identified within hemA have been found to result in a SCV in several bacterial genera, including Salmonella [3,13] and Listeria [14,15], as well as in E. coli [16]. The morphology of three SCVs of Listeria monocytogenes, all with a common SNP present in hemA resulting in early termination of the protein, were rescued when grown in the presence of exogenous hemin, suggesting they were auxotrophic for haem [15].…”

Section: Introductionmentioning

confidence: 99%

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A novel hemA mutation is responsible for a small-colony-variant phenotype in Escherichia coli

2021

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We identified a small colony variant (SCV) of an amoxicillin/clavulanic acid-resistant derivative of a clinical isolate of Escherichia coli from Malawi, which was selected for in vitro in a subinhibitory concentration of gentamicin. The SCV was auxotrophic for hemin and had impaired biofilm formation compared to the ancestral isolates. A single novel nucleotide polymorphism (SNP) in hemA, which encodes a glutamyl-tRNA reductase that catalyses the initial step of porphyrin biosynthesis leading to the production of haem, was responsible for the SCV phenotype. We showed the SNP in hemA resulted in a significant fitness cost to the isolate, which persisted even in the presence of hemin. However, the phenotype quickly reverted during sequential sub-culturing in liquid growth media. As hemA is not found in mammalian cells, and disruption of the gene results in a significant fitness cost, it represents a potential target for novel drug development specifically for the treatment of catheter-associated urinary tract infections caused by E. coli .

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“…Typical assays to test persistence include swarming and antibiotic-induced persistence. Reduced swarming has been correlated to persistence in several pathogens [37][38][39][40][41][42][43] . All three toxin mutant strains had reduced swarming motility even when supplemented with a higher concentration of glucose (Supplemental Figure S4A).…”

Section: Conservation and Expression Of The Predicted Host-associatedmentioning

confidence: 99%

Predicting toxins found in toxin–antitoxin systems with a role in host-induced Burkholderia pseudomallei persistence

Ross

Thiriot

Wilson

et al. 2020

Sci Rep

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Burkholderia pseudomallei (Bpm) is a bacterial pathogen that causes Melioidosis, a disease with up to 40% mortality and an infection relapse of 15–23% despite antibiotic treatment. Ineffective clearance of Bpm by antibiotics is believed to be due to persistence, a hibernation-like survival mechanism modulated, in part, by toxin–antitoxin systems (TAS). Several organisms possess a repertoire of TASs but defining environmental cues eliciting their activity is hindered by laborious in vitro experiments, especially when there are many toxins with redundant function. Here, we identified which of 103 proteins in Bpm that share features found in toxins of the TAS and repurposed transcriptional data to identify which ones play a role in surviving intracellular host defenses. Putative toxins with the strongest transcriptional response were found to have low conservation between Bpm strains, while toxins that were constitutively expressed were highly conserved. Further examination of highly conserved toxins BPSS0899, BPSS1321, and BPSL1494 showed that they were functional, and their mutation led to reduce survival within macrophages and reduced in vivo persistence-associated pathology (abscesses) during treatment, but did not affect macrophages persistence. These findings highlight the utility of a data-driven approach to select putative toxins and suggests a selective role for some TAS in host survival.

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The Small Colony Variant of Listeria monocytogenes Is More Tolerant to Antibiotics and Has Altered Survival in RAW 264.7 Murine Macrophages

Cited by 19 publications

References 59 publications

Tomatidine and analog FC04–100 possess bactericidal activities against Listeria, Bacillus and Staphylococcus spp

Tomatidine and analog FC04–100 possess bactericidal activities against Listeria, Bacillus and Staphylococcus spp

A novel hemA mutation is responsible for a small-colony-variant phenotype in Escherichia coli

Predicting toxins found in toxin–antitoxin systems with a role in host-induced Burkholderia pseudomallei persistence

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