Whole-genome sequencing of Klebsiella pneumoniae isolated from clinical specimens in Chattogram, Bangladesh.

The emergence of multidrug-resistant Klebsiella pneumoniae (Kpn) is a global concern due to the increasing rate of mortality and hospital cost burden in the affected population. This study reports the whole-genome sequences of nine multidrug-resistant Kpn from a hospital in Chattogram city of Bangladesh.

Genetic determinants of SARS-CoV-2 and the clinical outcome of COVID-19 in Southern Bangladesh.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has had a severe impact on population health. The genetic determinants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in southern Bangladesh are not well understood. METHODS: This study aimed to determine the genomic variation in SARS-CoV-2 genomes that have evolved over 2 years of the pandemic in southern Bangladesh and their association with disease outcomes and virulence of this virus. We investigated demographic variables, disease outcomes of COVID-19 patients and genomic features of SARS-CoV-2. RESULTS: We observed that the disease severity was significantly higher in adults (85.3%) than in children (14.7%), because the expression of angiotensin-converting enzyme-2 (ACE-2) diminishes with ageing that causes differences in innate and adaptive immunity. The clade GK (n = 66) was remarkable between June 2021 and January 2022. Because of the mutation burden, another clade, GRA started a newly separated clustering in December 2021. The burden was significantly higher in GRA (1.5-fold) highlighted in mild symptoms of COVID-19 patients than in other clades (GH, GK, and GR). Mutations were accumulated mainly in S (22.15 mutations per segment) and ORF1ab segments. Missense (67.5%) and synonymous (18.31%) mutations were highly noticed in adult patients with mild cases rather than severe cases, especially in ORF1ab segments. Moreover, we observed many unique mutations in S protein in mild cases compared to severe, and homology modeling revealed that those might cause more folding in the protein's alpha helix and beta sheets. CONCLUSION: Our study identifies some risk factors such as age comorbidities (diabetes, hypertension, and renal disease) that are associated with severe COVID-19, providing valuable insight regarding prioritizing vaccination for high-risk individuals and allocating health care and resources. The findings of this work outlined the knowledge and mutational basis of SARS-CoV-2 for the next treatment steps. Further studies are needed to confirm the effects of structural and functional proteins of SARS-CoV-2 in detail for monitoring the emergence of new variants in future.

Viral Inactivation and Biocompatibility Study of Electrically Activated Water Mist.

In addition to the ongoing global problem of healthcare-acquired infections, the COVID-19 pandemic continues to pose a serious threat to the health of the global population. This unprecedented pandemic situation has reinforced the need for the development of technologies that can curb the transmission of viruses among human beings and help to control the infection. Existing disinfection techniques using either ultraviolet light or harsh chemicals pose safety risks and are not suitable for use in the presence of humans. Thus, the need for a safe and effective disinfection technique that can be used in the presence of humans to control viral transmission is evident. A technique that can continuously disinfect air and surfaces in indoor environments, where the chances of viral transmission are high, can be an indispensable tool to fight such a pandemic. The Airlens Minus Corona (AMC) device provided by Persapien Innovations has been developed to achieve this goal. In this study, the antiviral functionality and biocompatibility of AMC were evaluated. Activated water mist (AWM) generated from this device was tested in vitro and in vivo for its toxicity to cell lines and in animal model. The AWM was found to be non-cytotoxic to L-929 cell lines and had no sign of clinical toxicity in an animal model (rabbit). This device was further used to inactivate animal viruses and bacteriophages. The AWM was found to be effective in the complete inactivation of influenza A H1N1 virus within 5 minutes of direct treatment. This device was also found to be effective in inactivating >90% of bacteriophage particles.

Genome Sequences of SARS-CoV-2 Sublineage B.1.617.2 Strains from 12 Children in Chattogram, Bangladesh.

We announce the complete genome sequences of 12 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sublineage B.1.617.2 strains (Delta variant) obtained from nasopharyngeal and oropharyngeal swab samples from 12 pediatric patients in Chittagong, Bangladesh, displaying COVID-19 symptoms. Oxford Nanopore MinION sequencing technology was used to generate the genomic sequences.

Acquisition of Plasmid-Mediated Colistin Resistance Gene mcr-1 in Escherichia coli of Livestock Origin in Bangladesh.

Aims: To investigate plasmid-borne colistin resistance mechanism (plasmid-mediated colistin resistance [mcr-1]) in Escherichia coli of human, veterinary, and environmental origin in Bangladesh. Materials and methods: A total of 810 samples were collected from different sources. Isolation and identification of E. coli was performed using classical bacteriology and then tested for antimicrobial susceptibility. Colistin-resistant isolates were further analyzed for mcr-1 gene using PCR. Minimum inhibitory concentration (MIC) was determined using microbroth dilution technique. After sequencing of mcr-1 gene, phylogenetics was conducted to see the relationship with other mcr-1 gene sequences. Results: A total of 358 E. coli were isolated from 810 samples of humans, animals, environment, and food in Bangladesh. Of them 49 (15.9%) isolates were phenotypically resistant to colistin and 254 (70.9%) were resistant to multiple antimicrobials. mcr-1 gene was detected in three E. coli isolates of poultry source. For the three mcr-1 positive isolates the MIC of colistin sulfate was 4, 8, and 128 µg/mL. Gene sequencing of two of the three mcr-1 positive isolates and phylogenetic analysis showed close similarities of one isolate to other mcr-1 sequences available at GenBank while the other appeared to have evolved locally. Conclusion: First-ever report on circulation of mcr-1 E. coli of livestock origin in Bangladesh.

Selection of retapamulin, a novel pleuromutilin for topical use.

The in vitro activity of retapamulin was determined and compared to that of topical and community antibiotics. The MIC(90)s of retapamulin against Staphylococcus aureus and Streptococcus pyogenes were 0.12 microg/ml and 0.016 microg/ml, respectively. Retapamulin has a low propensity to select resistance and produces an in vitro postantibiotic effect.

Characterization of Streptococcus pneumoniae TrmD, a tRNA methyltransferase essential for growth.

Down-regulation of expression of trmD, encoding the enzyme tRNA (guanosine-1)-methyltransferase, has shown that this gene is essential for growth of Streptococcus pneumoniae. The S. pneumoniae trmD gene has been isolated and expressed in Escherichia coli by using a His-tagged T7 expression vector. Recombinant protein has been purified, and its catalytic and physical properties have been characterized. The native enzyme displays a molecular mass of approximately 65,000 Da, suggesting that streptococcal TrmD is a dimer of two identical subunits. In fact, this characteristic can be extended to several other TrmD orthologs, including E. coli TrmD. Kinetic studies show that the streptococcal enzyme utilizes a sequential mechanism. Binding of tRNA by gel mobility shift assays gives a dissociation constant of 22 nM for one of its substrates, tRNA(Leu)(CAG). Other heterologous nonsubstrate tRNA species, like, tRNA (Thr)(GGT), tRNA(Phe), and tRNA (Ala)(TGC), bind the enzyme with similar affinities, suggesting that tRNA specificity is achieved via a postbinding event(s).

Characterization of a novel fucose-regulated promoter (PfcsK) suitable for gene essentiality and antibacterial mode-of-action studies in Streptococcus pneumoniae.

The promoter of the Streptococcus pneumoniae putative fuculose kinase gene (fcsK), the first gene of a novel fucose utilization operon, is induced by fucose and repressed by glucose or sucrose. When the streptococcal polypeptide deformylase (PDF) gene (def1, encoding PDF) was placed under the control of P(fcsK), fucose-dependent growth of the S. pneumoniae (P(fcsK)::def1) strain was observed, confirming the essential nature of PDF in this organism. The mode of antibacterial action of actinonin, a known PDF inhibitor, was also confirmed with this strain. The endogenous fuculose kinase promoter is a tightly regulated, titratable promoter which will be useful for target validation and for confirmation of the mode of action of novel antibacterial drugs in S. pneumoniae.

A global approach to identify novel broad-spectrum antibacterial targets among proteins of unknown function.

Attempted allelic replacement of 144 Streptococcus pneumoniae open reading frames of previously uncharacterized function led to the identification of 36 genes essential for growth under laboratory conditions. Of these, 14 genes (obg, spoIIIJ2, trmU, yacA, yacM, ydiC, ydiE, yjbN, yneS, yphC, ysxC, ytaG, yloI and yxeH4) were also essential in Staphylococcus aureus and Haemophilus influenzae or Escherichia coli, 2 genes (yrrK and ydiB) were only essential in H. influenzae as well as S. pneumoniae and 8 genes were necessary for growth of S.pneumoniae and S. aureus and did not have a homolog in H. influenzae(murD2, ykqC, ylqF, yqeH, ytgP, yybQ) or were not essential in that organism (yqeL, yhcT). The proteins encoded by these genes could represent good targets for novel antibiotics covering different therapeutic profiles. The putative functions of some of these essential proteins, inferred by bioinformatic analysis, are presented. Four mutants, with deletions of loci not essential for in vitro growth, were found to be severely attenuated in a murine respiratory tract infection model, suggesting that not all targets for antibacterial therapeutics are revealed by simple in vitro essentiality testing. The results of our experiments together with those collated from previously reported studies including Bacillus subtilis, E. coli and Mycoplasma sp. demonstrate that gene conservation amongst bacteria does not necessarily indicate that essentiality in one organism can be extrapolated to others. Moreover, this study demonstrates that different experimental procedures can produce apparently contradictory results.