1486. Phylogenetic and alpha toxin variant analyses of Staphylococcus aureus strains isolated from patients during the SAATELLITE study

Abstract Background Suvratoxumab is a human monoclonal antibody that neutralizes S. aureus (SA) alpha toxin (AT). SAATELLITE, a phase 2 study of the safety and efficacy of suvratoxumab for reducing the incidence of SA pneumonia (NCT02296320), was conducted within the consortium for Combatting Bacterial Resistance in Europe. Methods A total of 304 SA isolates (baseline, onset and last available isolates from suspected serious bacterial infections, SSBIs) collected from the lower respiratory tract samples from 165 subjects during SAATELLITE were subjected to whole genome sequencing. AT gene (hla) sequences were translated and amino acid variation was identified in comparison to the reference SA USA300 FPR3757. Phylogenetic analysis, genomic annotation and ST analysis were performed. AT expression in SA culture supernatants was performed by ELISA. Representative isolates with novel AT subtypes that had not been identified in previous studies were tested for hemolytic activity and suvratoxumab neutralizing activity. Wilcoxon rank sum test and Fisher’s exact test were performed, respectively: a) to compare difference in baseline AT expression in relation to SA pneumonia incidence; b) to evaluate the association between occurrence of AT stop codons and incidence of SA pneumonia at baseline, as well as the association between occurrence of AT stop codons and treatment arms at post baseline. Results We identified a total of 44 sequence types (STs) and 21 unique AT subtypes, 7 of which have not been described previously. No substitutions were located in the suvratoxumab binding region and all novel AT subtypes displaying lytic activity were neutralized by suvratoxumab. We detected stop codons Q113B and W205B in AT sequences in 53 and 2 SA isolates, respectively. We uncovered no significant associations of: 1) baseline AT expression with SA pneumonia incidence [p=0.967]; 2) occurrence of AT gene stop codon with either SA pneumonia incidence [p >0.999] or suvratoxumab treatment [p=0.103; lower frequency of stop codons in suvratoxumab arm versus placebo]. Conclusion Our data indicated that: 1) suvratoxumab target region in (AT) remains conserved; 2) suvratoxumab is active against all AT variants identified to date; 3) suvratoxumab did not exert pressure on SA clinical isolates for selection of escape mutants. Disclosures David E. Tabor, PhD, AstraZeneca (Employee, Shareholder) Andrey Tovchigrechko, PhD, AstraZeneca (Employee, Shareholder)KitePharma, a Gilead company (Employee, Shareholder) Bret R. Sellman, PhD, AstraZeneca (Employee, Shareholder) Michael McCarthy, n/a, AstraZeneca (Employee) Kathryn Shoemaker, MS, AstraZeneca (Employee) Hasan S. Jafri, MD, FAAP, AstraZeneca (Employee) Mark T. Esser, PhD, AstraZeneca (Employee) Alexey Ruzin, PhD, AstraZeneca (Employee, Shareholder)

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Ectopic Transcript Analysis Indicates that Allelic Exclusion is an Important Cause of Type I Protein C Deficiency in Patients with Nonsense and Frameshift Mutations in the PROC Gene

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650386 ◽

1996 ◽

Vol 75 (06) ◽

pp. 870-876 ◽

Cited By ~ 4

Author(s):

José Manuel Soria ◽

Lutz-Peter Berg ◽

Jordi Fontcuberta ◽

Vijay V Kakkar ◽

Xavier Estivill ◽

...

Keyword(s):

Splice Site ◽

Protein C ◽

Stop Codon ◽

Premature Stop Codon ◽

Allelic Exclusion ◽

Polymorphism Analysis ◽

Type I ◽

Protein C Deficiency ◽

Nonsense Mutations ◽

Stop Codons

SummaryNonsense mutations, deletions and splice site mutations are a common cause of type I protein C deficiency. Either directly or indirectly by altering the reading frame, these' lesions generate or may generate premature stop codons and could therefore be expected to result in premature termination of translation. In this study, the possibility that such mutations could instead exert their pathological effects at an earlier stage in the expression pathway, through “allelic exclusion” at the RNA level, was investigated. Protein C (PROC) mRNA was analysed in seven Spanish type I protein C deficient patients heterozygous for two nonsense mutations, a 7bp deletion, a 2bp insertion and three splice site mutations. Ectopic RNA transcripts from patient and control lymphocytes were analysed by RT-PCR and direct sequencing of amplified PROC cDNA fragments. The nonsense mutations and the deletion were absent from the cDNAs indicating that only mRNA derived from the normal allele had been expressed. Similarly for the splice site mutations, only normal PROC cDNAs were obtained. In one case, exclusion of the mutated allele could be confirmed by polymorphism analysis. In contrast to these six mutations, the 2 bp insertion was not associated with loss of mRNA from the mutated allele. In this case, cDNA analysis revealed the absence of 19 bases from the PROC mRNA consistent with the generation and utilization of a cryptic splice site 3’ to the site of mutation, which would result in a frameshift and a premature stop codon. It is concluded that allelic exclusion is a common causative mechanism in those cases of type I protein C deficiency which result from mutations that introduce premature stop codons

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Analysis of Stop Codons within Prokaryotic Protein-Coding Genes Suggests Frequent Readthrough Events

International Journal of Molecular Sciences ◽

10.3390/ijms22041876 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1876

Author(s):

Frida Belinky ◽

Ishan Ganguly ◽

Eugenia Poliakov ◽

Vyacheslav Yurchenko ◽

Igor B. Rogozin

Keyword(s):

Stop Codon ◽

Purifying Selection ◽

Protein Product ◽

Intermediate Step ◽

Protein Coding ◽

Stop Codons ◽

Protein Coding Genes ◽

Synonymous Sites ◽

Prokaryotic Protein ◽

Sense Codon

Nonsense mutations turn a coding (sense) codon into an in-frame stop codon that is assumed to result in a truncated protein product. Thus, nonsense substitutions are the hallmark of pseudogenes and are used to identify them. Here we show that in-frame stop codons within bacterial protein-coding genes are widespread. Their evolutionary conservation suggests that many of them are not pseudogenes, since they maintain dN/dS values (ratios of substitution rates at non-synonymous and synonymous sites) significantly lower than 1 (this is a signature of purifying selection in protein-coding regions). We also found that double substitutions in codons—where an intermediate step is a nonsense substitution—show a higher rate of evolution compared to null models, indicating that a stop codon was introduced and then changed back to sense via positive selection. This further supports the notion that nonsense substitutions in bacteria are relatively common and do not necessarily cause pseudogenization. In-frame stop codons may be an important mechanism of regulation: Such codons are likely to cause a substantial decrease of protein expression levels.

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Tackling Virulence of Pseudomonas aeruginosa by the Natural Furanone Sotolon

Antibiotics ◽

10.3390/antibiotics10070871 ◽

2021 ◽

Vol 10 (7) ◽

pp. 871

Author(s):

Mohammed F. Aldawsari ◽

El-Sayed Khafagy ◽

Ahmed Al Saqr ◽

Ahmed Alalaiwe ◽

Hisham A. Abbas ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Virulence Factors ◽

Bacterial Infections ◽

Therapeutic Agent ◽

Bacterial Resistance ◽

Inhibitory Concentration ◽

Bacterial Biofilm ◽

Resistant Bacteria ◽

Resistance Development

The bacterial resistance development due to the incessant administration of antibiotics has led to difficulty in their treatment. Natural adjuvant compounds can be co-administered to hinder the pathogenesis of resistant bacteria. Sotolon is the prevailing aromatic compound that gives fenugreek its typical smell. In the current work, the anti-virulence activities of sotolon on Pseudomonas aeruginosa have been evaluated. P. aeruginosa has been treated with sotolon at sub-minimum inhibitory concentration (MIC), and production of biofilm and other virulence factors were assessed. Moreover, the anti-quorum sensing (QS) activity of sotolon was in-silico evaluated by evaluating the affinity of sotolon to bind to QS receptors, and the expression of QS genes was measured in the presence of sotolon sub-MIC. Furthermore, the sotolon in-vivo capability to protect mice against P. aeruginosa was assessed. Significantly, sotolon decreased the production of bacterial biofilm and virulence factors, the expression of QS genes, and protected mice from P. aeruginosa. Conclusively, the plant natural substance sotolon attenuated the pathogenicity of P. aeruginosa, locating it as a plausible potential therapeutic agent for the treatment of its infections. Sotolon can be used in the treatment of bacterial infections as an alternative or adjuvant to antibiotics to combat their high resistance to antibiotics.

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Bacteriophages: A Revisited Strategy for the Treatment of Severe Bacterial Infections

JOURNAL OF BIOENGINEERING AND TECHNOLOGY APPLIED TO HEALTH ◽

10.34178/jbth.v2i3.74 ◽

2020 ◽

Vol 2 (3) ◽

pp. 78-79

Author(s):

Roberto Badaro

Keyword(s):

Antibiotic Resistance ◽

Resistance Genes ◽

Bacterial Infections ◽

Bacterial Resistance ◽

Phage Therapy ◽

Bacterial Pathogen ◽

Severe Infection ◽

Current Increase ◽

Therapeutic Alternative ◽

The Ideal

Bacteriophages are viruses that infect and parasitize bacteria. The current increase in the incidence of antibiotic resistance in human bacteria has favoredthe study of phages as a therapeutic alternative (phage therapy). Phage therapy is defined as the administration of virulent phages directly to a patient to lyse the bacterial pathogen that is causing a clinically severe infection. The ideal route of administration and modification of bacteriopaghes genetically to deactivate bacterial resistance genes is the next future to antibiotic recovery sensitivity of MDR organisms.

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A Review of the Combination Therapy of Low Frequency Ultrasound with Antibiotics

BioMed Research International ◽

10.1155/2017/2317846 ◽

2017 ◽

Vol 2017 ◽

pp. 1-14 ◽

Cited By ~ 13

Author(s):

Yun Cai ◽

Jin Wang ◽

Xu Liu ◽

Rui Wang ◽

Lei Xia

Keyword(s):

Combination Therapy ◽

Bacterial Infections ◽

Bacterial Resistance ◽

Low Frequency ◽

Bactericidal Effect ◽

Low Frequency Ultrasound ◽

Biofilm Bacteria ◽

Frequency Ultrasound

Single antimicrobial therapy has been unable to resist the global spread of bacterial resistance. Literatures of availablein vitroandin vivostudies were reviewed and the results showed that low frequency ultrasound (LFU) has a promising synergistic bactericidal effect with antibiotics against both planktonic and biofilm bacteria. It also can facilitate the release of antibiotics from medical implants. As a noninvasive and targeted therapy, LFU has great potential in treating bacterial infections. However, more in-depth and detailed studies are still needed before LFU is officially applied as a combination therapy in the field of anti-infective treatment.

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Bacteria-specific phototoxic reactions triggered by blue light and phytochemical carvacrol

Science Translational Medicine ◽

10.1126/scitranslmed.aba3571 ◽

2021 ◽

Vol 13 (575) ◽

pp. eaba3571

Author(s):

Min Lu ◽

Shen Wang ◽

Tao Wang ◽

Sisi Hu ◽

Brijesh Bhayana ◽

...

Keyword(s):

Blue Light ◽

Mammalian Cells ◽

Bacterial Infections ◽

Bacterial Resistance ◽

Combined Therapy ◽

Combined Treatment ◽

Multidrug Resistant ◽

Skin Wound ◽

Bacterial Colony ◽

Phototoxic Reaction

Development of alternatives to antibiotics is one of the top priorities in the battle against multidrug-resistant (MDR) bacterial infections. Here, we report that two naturally occurring nonantibiotic modalities, blue light and phytochemical carvacrol, synergistically kill an array of bacteria including their planktonic forms, mature biofilms, and persisters, irrespective of their antibiotic susceptibility. Combination but not single treatment completely or substantially cured acute and established biofilm-associated Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus infections of full thickness murine third-degree burn wounds and rescued mice from lethal Pseudomonas aeruginosa skin wound infections. The combined therapy diminished bacterial colony-forming units as high as 7.5 log10 within 30 min and introduced few adverse events in the survival of cocultured mammalian cells, wound healing, or host DNA. Mechanistic studies revealed that carvacrol was photocatalytically oxidized into a series of photoreactive substrates that underwent photolysis or additional photosensitization reactions in response to the same blue light, forming two autoxidation cycles that interacted with each other resulting in robust generation of cytotoxic reactive oxygen species. This phototoxic reaction took place exclusively in bacteria, initiated by blue light excitation of endogenous porphyrin-like molecules abundantly produced in bacteria compared with mammalian cells. Moreover, no bacterial resistance developed to the combined treatment after 20 successive passages. This highly selective phototoxic reaction confers a unique strategy to combat the growing threat of MDR bacteria.

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Dual functional β-peptide polymer-modified resin beads for bacterial killing and endotoxin adsorption

BMC Materials ◽

10.1186/s42833-019-0005-3 ◽

2019 ◽

Vol 1 (1) ◽

Cited By ~ 13

Author(s):

Yuxin Qian ◽

Yue Shen ◽

Shuai Deng ◽

Tingyan Liu ◽

Fan Qi ◽

...

Keyword(s):

Bacterial Infections ◽

Bacterial Resistance ◽

Resistant Bacteria ◽

High Concentration ◽

Major Step ◽

Bacterial Killing ◽

Host Defense Peptides ◽

Dual Functional ◽

Resin Beads ◽

Bacteria Killing

Abstract Background Bacterial infections and endotoxin contaminations are serious problems in the production/manufacture of food, water, drinks, and injections. The development of effective materials to kill bacteria and adsorb endotoxins, particularly those caused by gram-negative bacteria, represents a major step toward improved safety. As synthetic mimic of host defense peptides, β-peptide polymers are not susceptible to bacterial resistance and exhibit potent bacteria-killing abilities upon antibiotic-resistant bacteria. This study investigated the potential of synthetic β-peptide polymer-modified polyacrylate (PA) beads to kill bacteria and remove endotoxin, i.e. lipopolysaccharide (LPS), produced by these bacteria. Results Synthetic β-peptide polymer-modified PA beads displayed strong antimicrobial activity against Escherichia coli and methicillin-resistant Staphylococcus aureus, as well as excellent biocompatibility. In addition, these β-peptide polymer-modified beads removed around 90% of the endotoxins, even at 200 EU/mL of LPS, a very high concentration of LPS. Conclusions β-peptide polymer-modified PA beads are efficient in bacterial killing and endotoxin adsorption. Hence, these modified beads demonstrate the potential application in the production/manufacture of food, water, drinks, and injections.

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Avoiding ventilator-associated pneumonia: Curcumin-functionalized endotracheal tube and photodynamic action

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2006759117 ◽

2020 ◽

Vol 117 (37) ◽

pp. 22967-22973

Author(s):

Amanda C. Zangirolami ◽

Lucas D. Dias ◽

Kate C. Blanco ◽

Carolina S. Vinagreiro ◽

Natalia M. Inada ◽

...

Keyword(s):

Endotracheal Tube ◽

Bacterial Infections ◽

Bacterial Resistance ◽

Multidrug Resistant ◽

Resistant Bacteria ◽

Ventilator Associated Pneumonia ◽

Hospital Acquired Infection ◽

Hospital Acquired Infections ◽

Hospitalization Costs ◽

Hospital Acquired

Hospital-acquired infections are a global health problem that threatens patients’ treatment in intensive care units, causing thousands of deaths and a considerable increase in hospitalization costs. The endotracheal tube (ETT) is a medical device placed in the patient’s trachea to assist breathing and delivering oxygen into the lungs. However, bacterial biofilms forming at the surface of the ETT and the development of multidrug-resistant bacteria are considered the primary causes of ventilator-associated pneumonia (VAP), a severe hospital-acquired infection for significant mortality. Under these circumstances, there has been a need to administrate antibiotics together. Although necessary, it has led to a rapid increase in bacterial resistance to antibiotics. Therefore, it becomes necessary to develop alternatives to prevent and combat these bacterial infections. One possibility is to turn the ETT itself into a bactericide. Some examples reported in the literature present drawbacks. To overcome those issues, we have designed a photosensitizer-containing ETT to be used in photodynamic inactivation (PDI) to avoid bacteria biofilm formation and prevent VAP occurrence during tracheal intubation. This work describes ETT’s functionalization with curcumin photosensitizer, as well as its evaluation in PDI against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. A significant photoinactivation (up to 95%) against Gram-negative and Gram-positive bacteria was observed when curcumin-functionalized endotracheal (ETT-curc) was used. These remarkable results demonstrate this strategy’s potential to combat hospital-acquired infections and contribute to fighting antimicrobial resistance.

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Photophobia symptoms and visual pain thresholds in posttraumatic headache after mild traumatic brain injury

Neurology ◽

10.1212/01.wnl.0000550668.55103.10 ◽

2018 ◽

Vol 91 (23 Supplement 1) ◽

pp. S11.2-S11

Author(s):

Nicholas Jarvis ◽

Amaal J. Starling ◽

Todd J. Schwedt

Keyword(s):

Traumatic Brain Injury ◽

Brain Injury ◽

Pilot Study ◽

Mild Traumatic Brain Injury ◽

Light Sensitivity ◽

Fisher Exact Test ◽

Pain Thresholds ◽

Posttraumatic Headache ◽

Exact Test ◽

Wilcoxon Rank Sum Test

BackgroundLight sensitivity can be a disabling symptom in posttraumatic headache (PTH). The objective of this pilot study was to characterize photophobia symptoms and visual pain thresholds in PTH compared to healthy controls (HC).MethodsIndividuals with PTH attributed to mild traumatic brain injury (mTBI) (N = 18) and HC (N = 20), aged 18–65, were prospectively assessed using the Photosensitivity Assessment Questionnaire (PAQ), State Trait Anxiety Inventory (STAI), and Beck Depression Inventory (BDI). A progressive light stimulation device was used to quantify visual pain thresholds. Visual pain thresholds were determined by the intensity of light at which subjects first noted pain. The mean of 3 trials was considered the visual pain threshold. Two sample t-test, Wilcoxon rank sum test, χ2 test and Fisher exact test was used to compare the 2 groups for their demographics, clinical characteristics, and outcomes measures.ResultsThere were no differences in demographics including age, gender, or race. The average time since onset of PTH was 50.7 (73.6) months. Those with PTH had 15.8 (9.2) headache days per month. BDI and STAI scores were significantly higher in PTH compared to HC. Photophobia was higher in PTH compared to HC, 0.64 (0.25) vs 0.24 (0.24), p < 0.0001. Visual pain thresholds were lower in PTH (median 50.1 lux; quartiles 15.3 to 300.0) compared to HC (median 863.5 lux; quartiles 519.9 to 4,906.5; p = 0.0002).ConclusionPhotophobia symptoms are higher and visual pain thresholds are lower in PTH compared to HC. Light sensitivity is a well-known disabling symptom in PTH and this pilot study provides objective data through a validated photophobia scale and visual pain thresholds to characterize light sensitivity. Additional studies are needed to confirm this data, to compare acute to persistent PTH, to compare PTH to other headache disorders, and to determine if photophobia and visual pain thresholds will improve with intervention.

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N-alkylimidazolium Salts Functionalized with p-Coumaric and Cinnamic Acid: A Study of Their Antimicrobial and Antibiofilm Effects

Molecules ◽

10.3390/molecules24193484 ◽

2019 ◽

Vol 24 (19) ◽

pp. 3484

Author(s):

Oscar Forero-Doria ◽

Ramiro Araya-Maturana ◽

Anggela Barrientos-Retamal ◽

Luis Morales-Quintana ◽

Luis Guzmán

Keyword(s):

Antibacterial Activity ◽

Cinnamic Acid ◽

Bacterial Infections ◽

Bacterial Resistance ◽

Good Alternative ◽

Antibiofilm Activity ◽

Coumaric Acid ◽

Cinnamic Acids ◽

Gram Positive Bacteria ◽

Therapeutic Alternatives

The bacterial resistance to antibiotics has compromised the therapies used for bacterial infections. Nowadays, many strategies are being carried out to address this problem. Among them, the use of natural compounds like cinnamic and p-coumaric acids stands out. Nevertheless, their utilization is limited because of their unfavorable physicochemical properties. Due to the lack of new therapeutic alternatives for bacterial infections, novel strategies have emerged, such as the use of ionic liquids; given that they can show a broad spectrum of antibacterial activity, this is why we herein report the antibacterial and antibiofilm activity of a series of N-alkylimidazolium salts functionalized with p-coumaric and cinnamic acids. The results from this study showed better antibacterial activity against Gram-positive bacteria, with a predominance of the salts derived from coumaric acid and a correlation with the chain length. Additionally, a lower efficacy was observed in the inhibition of biofilm formation, highlighting the antibiofilm activity against Staphylococcus aureus, which decreased the production of the biofilm by 52% over the control. In conclusion, we suggest that the salts derived from p-coumaric acid are good alternatives as antibacterial compounds. Meanwhile, the salt derived from cinnamic acid could be a good alternative as an antibiofilm compound.

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