A Search for Anti-Naegleria fowleri Agents Based on Competitive Exclusion Behavior of Microorganisms in Natural Aquatic Environments

Naegleria fowleri causes deadly primary amoebic meningoencephalitis (PAM) in humans. Humans obtain the infection by inhaling water or dust contaminated with amebae into the nostrils, wherefrom the pathogen migrates via the olfactory nerve to cause brain inflammation and necrosis. Current PAM treatment is ineffective and toxic. Seeking new effective and less toxic drugs for the environmental control of the amoeba population to reduce human exposure is logical for the management of N. fowleri infection. On the basis of the concept of competitive exclusion, where environmental microorganisms compete for resources by secreting factors detrimental to other organisms, we tested cell-free culture supernatants (CFSs) of three bacteria isolated from a fresh water canal, i.e., Pseudomonas aeruginosa, Pseudomonas otitidis, and Enterobacter cloacae, were tested against N. fowleri. The CFSs inhibited growth and caused morphological changes in N. fowleri. At low dose, N. fowleri trophozoites exposed to P. aeruginosa pyocyanin were seen to shrink and become rounded, while at high dose, the trophozoites were fragmented. While the precise molecular mechanisms of pyocyanin and products of P. otitidis and E. cloacae that also exert anti-N. fowleri activity await clarification. Our findings suggest that P. aeruginosa pyocyanin may have a role in the control of amphizoic N. fowleri in the environment

SARS-CoV-2 Variants by Whole-Genome Sequencing in a University Hospital in Bangkok: First to Third COVID-19 Waves

Background: Multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants emerged globally during the recent coronavirus disease (COVID-19) pandemic. From April 2020 to April 2021, Thailand experienced three COVID-19 waves, and each wave was driven by different variants. Therefore, we aimed to analyze the genetic diversity of circulating SARS-CoV-2 using whole-genome sequencing analysis. Methods: A total of 33 SARS-CoV-2 positive samples from three consecutive COVID-19 waves were collected and sequenced by whole-genome sequencing, of which, 8, 10, and 15 samples were derived from the first, second, and third waves, respectively. The genetic diversity of variants in each wave and the correlation between mutations and disease severity were explored. Results: During the first wave, A.6, B, B.1, and B.1.375 were found to be predominant. The occurrence of mutations in these lineages was associated with low asymptomatic and mild symptoms, providing no transmission advantage and resulting in extinction after a few months of circulation. B.1.36.16, the predominant lineage of the second wave, caused more symptomatic COVID-19 cases and contained a small number of key mutations. This variant was replaced by the VOC alpha variant, which later became dominant in the third wave. We found that B.1.1.7 lineage-specific mutations were crucial for increasing transmissibility and infectivity, but not likely associated with disease severity. There were six additional mutations found only in severe COVID-19 patients, which might have altered the virus phenotype with an inclination toward more highly pathogenic SARS-CoV-2. Conclusion: The findings of this study highlighted the importance of whole-genome analysis in tracking newly emerging variants, exploring the genetic determinants essential for transmissibility, infectivity, and pathogenicity, and helping better understand the evolutionary process in the adaptation of viruses in humans

Effect of heat on antimicrobial activity of the EF478 CFS.

<p>Effect of heat on antimicrobial activity of the EF478 CFS.</p

Effect of enzymatic treatments on activity of the EF478 CFS.

<p>Effect of enzymatic treatments on activity of the EF478 CFS.</p

A novel bacteriocin from <i>Enterococcus faecalis</i> 478 exhibits a potent activity against vancomycin-resistant enterococci

<div><p>The emergence of multidrug-resistant enterococci (MDRE) and particularly vancomycin-resistant enterococci (VRE) is considered a serious health problem worldwide, causing the need for new antimicrobials. The aim of this study was to discover and characterize bacteriocin against clinical isolates of MDRE and VRE. Over 10,000 bacterial isolates from water, environment and clinical samples were screened. <i>E</i>. <i>faecalis</i> strain 478 isolated from human feces produced the highest antibacterial activity against several MDRE and VRE strains. The optimum condition for bacteriocin production was cultivation in MRS broth at 37°C, pH 5–6 for 16 hours. The bacteriocin-like substance produced from <i>E</i>. <i>faecalis</i> strain EF478 was stable at 60°C for at least 1 hour and retained its antimicrobial activity after storage at -20°C for 1 year, at 4°C for 6 months, and at 25°C for 2 months. A nano-HPLC electrospray ionization multi-stage tandem mass spectrometry (nLC-ESI-MS/MS) analysis showed that the amino acid sequences of the bacteriocin-like substance was similar to serine protease of <i>E</i>. <i>faecalis</i>, gi|488296663 (NCBI database), which has never been reported as a bacteriocin. This study reported a novel bacteriocin with high antibacterial activity against VRE and MDRE.</p></div

Efficacy of SARS-CoV-2 detection from used surgical masks compared with standard detection method

The real-time reverse transcription-polymerase chain reaction (RT-PCR) test is the gold standard for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection. Proper specimen collection and obtaining a sufficient specimen are the most essential steps for laboratory diagnosis. The nasopharyngeal (NP) swab is recommended as the reference collection method. However, NP swab collection is invasive and uncomfortable for patients and poses some risk to healthcare workers. This study aimed to compare the efficacy of SARS-CoV-2 RNA detection from surgical masks with the NP swab method using RT-PCR testing. Of 269 patients, RT-PCR RNA from NP swabs was detected among 82 patients (30.5%) and was undetected among 187 patients (69.5%). All patients were tested for SARS-CoV-2 RNA from surgical masks. SARS-CoV-2 RNA was detected in 25/82 (30.5%) surgical mask filters, while undetected among 57 (69.5%). For the surgical mask with an average use time of 7.05 h, the sensitivity was 30.5%, the specificity was 100.0%, with positive predictive value of 100.0% and negative predictive value of 76.2%. Therefore, surgical masks could be an alternative non-invasive specimen source for SARS-CoV-2 RT-PCR testing. The results of our study suggest that the test could be employed after wearing surgical masks for at least 8-12 h, with increased sensitivity when used for more than 12 h

Ribbon diagrams of EF478 bacteriocin and <i>E</i>. <i>faecalis</i> serine protease.

<p><b>WP_002367871:</b> (A) EF478 bacteriocin, (B) <i>E</i>. <i>faecalis</i> serine protease WP_002367871. The zoomed in region is the CAP superfamily domain. There is only one amino acid difference between EF478 bacteriocin and <i>E</i>. <i>faecalis</i> serine protease WP_002367871, but they have a big difference in their secondary structure and perhaps their functions. α-helices (red), β-sheets (blue) and bulge (green).</p

Effect of pH on antimicrobial activity of the EF478 CFS.

<p>Effect of pH on antimicrobial activity of the EF478 CFS.</p

Peptide fingerprinting report of EF478 using Mascot search engine.

<p>Peptide fingerprinting report of EF478 using Mascot search engine.</p