| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Dahdouh, Elias, et al.
(författare)
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Computational Modeling and Design of New Inhibitors of Carbapenemases : A Discussion from the EPIC Alliance Network
- 2022
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 23:17
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The EPIC consortium brings together experts from a wide range of fields that include clinical, molecular and basic microbiology, infectious diseases, computational biology and chemistry, drug discovery and design, bioinformatics, biochemistry, biophysics, pharmacology, toxicology, veterinary sciences, environmental sciences, and epidemiology. The main question to be answered by the EPIC alliance is the following: "What is the best approach for data mining on carbapenemase inhibitors and how to translate this data into experiments?" From this forum, we propose that the scientific community think up new strategies to be followed for the discovery of new carbapenemase inhibitors, so that this process is efficient and capable of providing results in the shortest possible time and within acceptable time and economic costs.
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| 3. |
- El Zowalaty, Mohamed E., et al.
(författare)
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Draft genome sequence of Cronobacter sakazakii strain MEZCS99 sequence type 3 isolated from chicken in South Africa
- 2022
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Ingår i: Journal of Global Antimicrobial Resistance. - : Elsevier. - 2213-7165 .- 2213-7173. ; 31, s. 292-294
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Cronobacter sakazakii is an emerging opportunistic foodborne pathogen that is frequently as-sociated with life-threatening infections such as infantile septicemia, meningitis, and necrotizing entero-colitis. The emergence of antimicrobial-resistant, livestock-associated C. sakazakii is a great public health concern. Here, we report on the first draft genome sequence of C. sakazakii strain MEZCS99 sequence type 3 (ST3) isolated from feces from a healthy chicken in KwaZulu-Natal Province, South Africa.Methods: The genomic DNA of C. sakazakii was sequenced using an Illumina MiSeq platform (Illumina Inc., San Diego, CA). Generated reads were trimmed and de novo assembled. The assembled contigs were analyzed for virulence and antimicrobial resistance genes, extra-chromosomal plasmids, and multi -locus sequence type (MLST). To compare the sequenced strains to other previously sequenced C. sakazakii strains, available raw read sequences of C. sakazakii were downloaded and all sequence files were treated identically to generate a core genome phylogenetic tree.Results: Intrinsic beta-lactam resistance gene blaCSA-1 was detected in MEZCS99. No colistin or other antibiotic resistance genes were detected. MEZCS99 belonged to ST3 and harbored an extra-chromosomal plasmid (IncFIB (pCTU3)). The genome of MEZCS99 strain showed two CRISPR/Cas cluster arrays of I-E (n = 1) and I-F (n = 1) type.Conclusion: The genome sequence of strain MEZCS99 will serve as a reference point for molecular epi-demiological studies of livestock-associated C. sakazakii in Africa. In addition, this study allows in-depth analysis of the genomic structure and will provide valuable information that helps understand the patho-genesis and antimicrobial resistance of livestock-associated C. sakazakii.
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| 4. |
- Eze, Emmanuel C., et al.
(författare)
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Draft genome sequences of extensively drug resistant and pandrug resistant Acinetobacter baumannii strains isolated from hospital wastewater in South Africa
- 2022
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Ingår i: Journal of Global Antimicrobial Resistance. - : Elsevier. - 2213-7165 .- 2213-7173. ; 31, s. 286-291
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Acinetobacter baumannii is a significant opportunistic pathogen causing nosocomial infections. Infections caused by A. baumannii are often difficult to treat because this bacterium is often multidrug-resistant and shows high environmental adaptability. Here, we report on the analysis of three A. bauman-nii strains isolated from hospital effluents in South Africa.Methods: Strains were isolated on Leeds Acinetobacter agar and were identified using VITEK (R) 2 platform. Antibiotic susceptibility testing was performed using the Kirby-Bauer Disk diffusion method. Whole-genome sequencing was performed. The assembled contigs were annotated. Multilocus sequence type, antimicrobial resistance, and virulence genes were identified.Results: The strains showed two multilocus sequence types, ST231 (FA34) and ST1552 (PL448, FG116). Based on their antibiotic susceptibility profiles, PL448 and FG116 were classified as extensively drug -resistant and FA34 as pandrug-resistant. FA34 harbored mutations in LpxA, LpxC, and PmrB, conferring resistance to colistin, but not mcr genes. All three strains encoded virulence genes for immune evasion (capsule, lipopolysaccharide [LPS]), iron uptake, and biofilm formation. FA34 was related to human strains from South Africa; PL448 and FG116 were related to a strain isolated in the United States from a human wound.Conclusions: The detection of extensively drug-and pandrug-resistant A. baumannii strains in hospital effluents is of particular concern. It indicates that wastewater might play a role in the spread of these bacteria. Our data provide insight into the molecular epidemiology, resistance, pathogenicity, and distri-bution of A. baumannii in South Africa.
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| 5. |
- Eze, Emmanuel C., et al.
(författare)
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Genome sequence of a carbapenemase-encoding Acinetobacter baumannii isolate of the sequence type 231 isolated from hospital wastewater in South Africa
- 2022
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Ingår i: Journal of Global Antimicrobial Resistance. - : Elsevier. - 2213-7165 .- 2213-7173. ; 29, s. 150-154
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Tidskriftsartikel (refereegranskat)abstract
- ObjectivesThe resistome, virulome, mobilome and phylogenetic relationship of the Acinetobacter baumannii isolate FG121 depicting the multilocus sequence type (ST) 231 isolated from hospital effluent water in South Africa was determined using whole-genome sequence analysis.MethodA. baumannii FG121 was isolated on Leed Acinetobacter Medium (LAM) agar and the bacterial isolate was identified using the VITEK®2 platform. Antibiotic susceptibility testing was performed using Kirby–Bauer Disk diffusion method. A whole genome sequencing library was constructed from DNA extracted from the isolate using the Illumina Nextera XT library preparation kit and was sequenced using the Illumina NextSeq500 platform. Generated reads were de novo assembled using SpAdes v.3.9. The assembled contigs were annotated, and multilocus sequence type, antimicrobial resistance, and virulence genes were identified.ResultsThe resistome was consistent with the resistance phenotype of the isolate with resistance determinants for beta-lactams, aminoglycosides, and tetracycline (blaADC-25, blaOXA-23, blaOXA-51, blaNDM-1, aph[3’]-VIa and tet[B]). Global phylogenomic analysis using BacWGSTdb revealed that the isolate belonged to the multilocus sequence type ST-231, similar to previously reported isolates from South Africa, the United States, and related to the invasive KR3831 isolate identified from Oman in 2012, suggesting the isolate might be imported from abroad. Virulome analysis predicted both virulence and biofilm-determinants of A. baumannii, which may help to establish infections in adverse conditions.ConclusionThis is the first report on a carbapenemase-encoding A. baumannii ST-231 isolated from hospital effluent water. Our data will offer insight into the global phylogenetic, pathogenicity and distribution of A. baumannii in South Africa.
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