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Volume 5,
Issue 2,
2023
Volume 5, Issue 2, 2023
- Research Articles
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Synergistic antimicrobial effect of ascorbic acid and nicotinamide with rifampicin and vancomycin against SCCmec type IV methicillin-resistant Staphylococcus aureus (MRSA)
More LessBackground. Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogenic bacteria involved in a wide spectrum of human diseases. Many virulence factors promote this widespread propagation. One important factor is acquiring antibiotic resistance genes, which leads to a reduction in the availability and efficacy of therapy options. Recently, research has suggested that the remarkable antimicrobial effect of antioxidants against superbugs such as MRSA shows synergistic effects when accompanied by antimicrobial therapy. This paper aims to examine the synergistic effects of ascorbic acid and nicotinamide with a panel of antibiotics used in antimicrobial therapy against MRSA.
Material and Methods. Two SCCmec type IV MRSA reference strains (EMRSA-15 and USA300) and 10 MRSA clinical isolates feature in this paper. SCCmec typing was conducted on the 10 clinical isolates via multiplex PCR after identification. Synergy experiments on antioxidants and antibiotics were evaluated via checkerboard assay. The minimum inhibitory concentration (MIC) of each agent was determined in accordance with the Clinical and Laboratory Standards Institute (CLSI) M100 guidelines through twofold microdilution assay.
Results and Discussion. Synergy (FIC <0.5) was demonstrated for ascorbic acid (1/2 to 1/4 MIC) with rifampicin (1/2 to 1/8 MIC), and also ascorbic acid (1/2 to 1/16 MIC) when associated with vancomycin (1/2 MIC). Similarly, nicotinamide (1/2 to 1/16 MIC) showed a synergistic effect when paired with low concentrations of rifampicin (1/2 to 1/16 MIC), and also (at 1/4 to 1/16 MIC) with vancomycin (1/2 MIC). All reduced MICs due to synergistic combinations demonstrated statistical significance (P<0.05).
Conclusion. The synergistic activity demonstrated in associating antioxidants with antibiotics shows promise in managing superbugs. However, more research is required to better understand the mechanism of the synergy and for utilization in clinical care.
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Evaluation of five commercial DNA extraction kits using Salmonella as a model for implementation of rapid Nanopore sequencing in routine diagnostic laboratories
More LessOxford Nanopore long-read sequencing offers advantages over Illumina short reads for the identification and characterization of bacterial pathogens for outbreak detection and surveillance activities within a diagnostic public health laboratory context. Compared to Illumina, Nanopore is more cost-effective for small batches, has a lower capital cost and has a faster turnaround time, in addition to the ability to assemble complete bacterial genomes. The quantity and quality of DNA required for Nanopore sequencing are greater than for Illumina, and the DNA extraction methods recommended for obtaining high-molecular-weight DNA are different from those typically used in diagnostic laboratories. Using a Salmonella isolate with a previously closed PacBio genome as a model Enterobacteriaceae organism, we evaluated the quantity, quality and fragmentation of five commercial DNA extraction kits. Nanopore sequencing performance was evaluated for the top three methods: Qiagen EZ1 DNA Tissue, Qiagen DNeasy Blood and Tissue, and a modified, in-house version of the MasterPure Complete DNA and RNA purification. To evaluate the effect of post-extraction DNA purification methods, we subjected extracted DNA from the three selected extraction methods to purification by AMPure beads or ethanol precipitation and compared these outputs with untreated DNA as a control. All methods are suitable for routine whole-genome sequencing (WGS), since all 60 replicates had very high genome recovery rates, with ≥98 % of the reference genome covered by mapped Nanopore reads. For 85 % of the replicates, assembly was able to produce a complete, circular chromosome using either Flye or Canu. In most cases, it is recommended to move directly from extraction to sequencing, as untreated DNA had the highest rates of genome closure regardless of extraction method. Using our evaluation criteria, the Qiagen DNeasy Blood and Tissue kit was found to be the best overall method due to its low cost, ability to scale from single tubes to 96-well plates, and high consistency in yield and sequencing performance.
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- Short Communications
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Vaccine-induced neutralizing antibodies against SARS-CoV-2 Omicron variant isolated in Osaka, Japan
More LessTo study vaccine-induced neutralizing antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants isolated in Osaka, Japan, microneutralization tests were performed on serum samples from 32subjects who received a second dose of vaccination, and 10 of those who received the third dose of vaccination. Geometric mean titres (GMTs) for the D614G strain, Alpha variant, Delta variant, and Omicron BA.1 of the subjects after the second dose of vaccination were 19.5, 21.8, 6.3 and 2.0, respectively. The GMT for the Delta variant was significantly lower than that for the D614G strain and Alpha variant, and the GMT for the Omicron BA.1 was significantly lower than that for the Delta variant. Among the subjects who received three doses of vaccination, the GMTs for the Omicron BA.1 (62.8) and BA.2 (38.6) were significantly higher than that for the Omicron BA.1 after the second dose. Thus, in the present study, the second dose of vaccination induced neutralizing antibodies against SARS-CoV-2 strains, and the reactivity of neutralizing antibodies to the variants was thought to be enhanced by the third dose of vaccination. The serum samples used in this study will be useful in evaluating the reactivity of vaccine-induced antibodies to newly emerging variants.
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Mortality difference from Klebsiella aerogenes vs Enterobacter cloacae bloodstream infections
More LessMembers of the order Enterobacterales, including Escherichia coli , Klebsiella species and Enterobacter species, are important pathogens in healthcare-associated infections. Higher mortality has been reported from infections due to Klebsiella pneumoniae than from E. coli , but prior studies comparing Enterobacter aerogenes (recently renamed Klebsiella aerogenes ) bacteraemia and Enterobacter cloacae complex bacteraemia have yielded conflicting results regarding whether clinical outcomes differ. We found bacteraemia with K. aerogenes was independently associated with greater risk of 30-day mortality than bacteraemia with Enterobacter cloacae complex.
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- Methods
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Investigating Klebsiella pneumoniae biofilm preservation for scanning electron microscopy
More LessKlebsiella pneumoniae biofilm formation is associated with chronic and relapsing infections. Scanning electron microscopy (SEM) is a powerful tool for characterizing biofilm structure and studying their formation. Reliable visualization of biofilm structure requires careful sample preservation, otherwise there may be loss of non-covalent interactions that are susceptible to damage during the dehydration and washing preparation steps. However, no standard procedure has been adopted in the literature to fix K. pneumoniae biofilm for scanning electron microscopy studies. This lack of standardization makes it challenging to compare results between studies and determine the degree to which native structures have been preserved. To advance this critical area of study, we investigated different scanning electron microscopy fixation methods for K. pneumoniae biofilm preservation. Our study reveals the impact preparation steps can have on retaining in biofilm architecture observed using scanning electron microscopy. Using fixation methods developed through our studies, we show that although species that overproduce capsular extracellular polysaccharides produced more robust biofilms, K. pneumoniae can form a developed biofilm in the absence of capsular polysaccharides.
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- Pedagogy
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Building blocks of biofilms – an engaging and hands-on microbiology outreach activity for school children and the general public
More LessBiofilms are naturally occurring communities of micro-organisms, attached to a surface and often embedded in a matrix of self-produced polymeric substances. Biofilms are widely implicated in human infections, particularly on prostheses and medical implants. Such biofilms are difficult to eradicate, often leading to replacement of the prosthesis and resulting in a significant burden to healthcare. Here we present a fun and engaging interactive activity targeted toward primary school/early secondary school children, introducing the concept of natural and healthcare-associated biofilms, using dental plaque as an archetypal example. Dental plaque forms as a result of poor oral/dental hygiene, and develops according to a typical series of defined stages: attachment and adherence to the surface, followed by colonization and maturation of the biofilm structure, and eventually, dispersal. This activity uses dental disclosing tablets to visualize real biofilms (plaque) on the participants teeth, and uses interlocking building-blocks to represent microorganisms, where children build three-dimensional ‘biofilms’ of varying shapes and structural integrities. Each of the stages of development are discussed in detail, and after building the biofilms, balls of different shapes, sizes and weights can be used as ‘antimicrobials’ to disrupt the biofilm structure. The outcomes of the activity are to enhance knowledge and general understanding of biofilms; their ubiquitous presence in the natural environment, development, implications in healthcare, and challenges of treatment. The various ‘antimicrobial’ balls also provide a basis to introduce and discuss drug selection for infections, and the importance of using the correct antimicrobial for different infections to avoid development of resistance.
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Prevalence and resistance pattern of uropathogens from community settings of different regions: an experience from India
Sarita Mohapatra, Rajashree Panigrahy, Vibhor Tak, Shwetha J. V., Sneha K. C., Susmita Chaudhuri, Swati Pundir, Deepak Kocher, Hitender Gautam, Seema Sood, Bimal Kumar Das, Arti Kapil, Pankaj Hari, Arvind Kumar, Rajesh Kumari, Mani Kalaivani, Ambica R., Harshal Ramesh Salve, Sumit Malhotra and Shashi Kant
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