Genomic Characterisation of Methicillin-Resistant and Methicillin-Susceptible <em>Staphylococcus aureus </em>Implicated in Bloodstream Infections, KwaZulu Natal, South Africa
Bibliographic record
Abstract
Staphylococcus aureus is an opportunistic human pathogen and a leading cause of bloodstream infections. It can acquire different antibiotic resistance genes, leading to treatment failure. Aim: We elaborate on the genomic characteristics; antibiotic resistance, virulence, pathogenicity, phylogenomics and clonal diversity of S. aureus implicated in bloodstream infections. Six multidrug-resistant (MDR) S. aureus, three methicillin-resistant S. aureus (MRSA) and three methicillin-sensitive S. aureus obtained from blood cultures underwent whole genome sequencing and bioinformatics analysis. All isolates carried different permutations and combinations of resistance genes including, blaZ, mecA, aac(6')-aph (2''), ant(9)-Ia, ant(6)-Ia, mepR, fosB, norA, norC, lmrS, arlS, arlR, mgrA, kdpD and sdrM. We found 6 spa types (t9475, t355, t045, t1265, t1257, and t7888) with varying profiles of virulence genes responsible for immune invasion, enterotoxins, adhesion/biofilm, haemolysins, and leukotoxins. Panton-Valentine leukocidin (Luk-PV) was found in one MSSA isolate. Two SCCmec types IVd(2B) and I(1B) were identified. Isolates belonged to four multilocus sequence types (MLSTs), the most common of which was ST5 (n=3). The STs were clustered into two clonal complexes CC5 and CC8. We found two MRSA clones typed as ST5-CC5-t045-SCCmec_I(1B), and the human-associated MRSA endemic clone ST612-CC8-t1257-SCCmec_IVd(2B). The insertion sequences IS30 and IS6 associated with virulence were found in two isolates. The presence of virulent MDR S. aureus in bloodstream infections poses a clinical concern because of limited treatment options and increased risk of mortality.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".