Methicillin-Resistant <i>Staphylococcus aureus</i> Nasal Carriage among Injection Drug Users: Six Years Later
Bibliographic record
Abstract
A survey in 2000 to detect methicillin-resistant Staphylococcus aureus (MRSA) colonization in Vancouver downtown east side injection drug users (IDUs) revealed an MRSA nasal colonization incidence of 7.4%. This is a follow-up study to determine the current prevalence of MRSA colonization and to further characterize the isolates and risk factors for colonization. In this point prevalence study of MRSA nasal carriage among IDUs, nasal swabs were cultured to detect S. aureus. Isolates were studied for their antimicrobial susceptibility patterns and the presence of mecA and Panton-Valentine leukocidin (PVL) genes and by pulsed-field gel electrophoresis (PFGE). S. aureus was isolated from 119 of 301 (39.5%) samples; three (2.5%) participants had both methicillin-sensitive S. aureus (MSSA) and MRSA, resulting in 122 isolates. Of these, 54.1% were MSSA and 45.9% were MRSA, with an overall MRSA rate of 18.6%. USA-300 (CMRSA-10) accounted for 75% of all MRSA isolates; 25% were USA-500 (CMRSA-5). None of the USA-500 isolates were positive for PVL; 41 (97.6%) USA-300 isolates contained PVL. One MSSA isolate, from an individual also carrying USA-300, was positive for PVL. The PFGE pattern of this MSSA isolate was related to that of the MRSA strain. The antibiograms of USA-300 compared to USA-500 isolates showed 100% versus 7.1% susceptibility to trimethoprim-sulfamethoxazole (TMP-SMX) and 54.8% versus 7.1% susceptibility to clindamycin. MRSA nasal colonization in this population has increased significantly within the last 6 years, with USA-300 replacing the previous strain. Most of these strains are PVL positive, and all are susceptible to TMP-SMX.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".