<i>In vitro</i> susceptibility to β-lactam antibiotics and viability of <i>Neisseria gonorrhoeae</i> strains producing plasmid-mediated broad- and extended-spectrum β-lactamases
Bibliographic record
Abstract
ABSTRACT N. gonorrhoeae strains producing plasmid-mediated broad- and extended-spectrum β-lactamases (ESBLs) have been obtained in vitro and studied for their viability and susceptibility to β-lactam antibiotics. The artificial p bla TEM-1 and p bla TEM-20 plasmids were constructed by site-directed mutagenesis from a p bla TEM-135 plasmid of the Toronto/Rio type, which was extracted from the clinical isolate. MIC values were determined for a series of β-lactam antibiotics, including benzylpenicillin, ampicillin, cefuroxime, ceftriaxone, cefixime, cefotaxime, cefepime, meropenem, imipenem, and doripenem. The N. gonorrhoeae strain carrying the p bla TEM-20 plasmid exhibited a high level of resistance to penicillins and II-IV generation cephalosporins (MIC ≥ 2 mg/L) but not to carbapenems (MIC ≤ 0.008 mg/L). However, this strain stopped growing after 6 hours of cultivation. The reduced viability was not associated with the plasmid loss but can be explained by the following factors: the presence of the plasmid itself, which requires additional costs for its reproduction, and the expression of ESBL, which can affect the structure of the peptidoglycan layer in the cell membrane. The cell growth was mathematically modeled using the generalized Verhulst equation. The parameter, characterizing the maximum possible number of cells grown under given conditions, decreased within the wild type (without plasmids) - p bla TEM-135 - p bla TEM-1 - p bla TEM-20 series, i.e. , the plasmid-bearing strains had reduced viability compared to that of the wild-type strain. The kinetics for the cell death of N. gonorrhoeae strains without the p bla TEM-20 plasmid in the presence of ceftriaxone can be described by a modified Chick-Watson law. For the N. gonorrhoeae strain that harbors the p bla TEM-20 plasmid, the kinetics for cell number changes with time reflected several processes: the hydrolysis of ceftriaxone by TEM-20 β-lactamase, growth and gradual death of cells. The demonstrated reduced viability of N. gonorrhoeae strains with the p bla TEM-20 plasmid probably explains the absence of clinical isolates of N. gonorrhoeae that produce ESBL.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".