A Retrospective Review of Treatment Appropriateness and Outcomes of Enterobacteriaceae (With Inducible ampC Beta [β]-lactamase) Bacteremias at a Large Academic Medical Centre: Opportunities and Implications for Antimicrobial Stewardship
Bibliographic record
Abstract
Background. Infections caused by ampC carrying Enterobacteriaceae can be problematic. β-lactamase production in these organisms can be inducible upon exposure to β-lactams and lead to treatment failure. Choice of antimicrobial therapy is important, as delay in appropriate empiric therapy is associated with mortality, while avoiding unneeded broad-spectrum antimicrobials is an important component of antimicrobial stewardship. There is little data to support the current practice of carbapenems as first-line agents to treat ampC Enterobacteriaceae infections, and a recent study showed cefepime to be as effective as carbapenems. We aimed to study treatment appropriateness and outcomes for ampC Enterobacteriaceae, and explore outcomes for carbapenem-sparing agents. Methods. Microbiology reports identified 49 patients with bacteremia caused by ampC carrying Enterobacteriaceae over 2 years at a large academic medical center. Appropriateness of empiric and definitive therapy was assessed by 2 independent reviewers. Demographics, comorbidities, microbiology, and antibiogram data was also collected. Clinical outcomes included all-cause mortality, length of stay, and microbiological cure. Results. Only 12% of Enterobacteriaceae bacteremias presented with derepression of the ampC gene upon first culture. Empiric therapy was appropriate (active based on sensitivity) in 78% of patients. For empiric therapy, most received piperacillin-tazobactam [P/T] (61%), while few (8%) received a carbapenem. Definitive therapy was often a fluoroquinolone [FQN] (63%); the rest received a carbapenem (10%), sulfamethoxazole-trimethoprim [SMX-TMP] (8%), or P/T (8%). Five patients (10%) had bacteremia persisting >1 day. In patients with appropriate definitive therapy, clinical outcomes were not different (carbapenem versus non-carbapenem). Conclusion. The majority of patients studied received an appropriate non-carbapenem as definitive therapy with good microbiological and clinical outcomes. The majority of patients also received appropriate empiric therapy. We suggest that non-β-lactams, especially SMX-TMP, should be explored as carbapenem-sparing options for ampC carrying Enterobacteriaceae which represent a large proportion of Gram-negative infections. Future work should focus on confirming clinical outcomes in a broader sample. Disclosures. All authors: No reported disclosures.
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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 | 0.002 | 0.008 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.004 | 0.006 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| 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".