Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 3 complete abstracts (687 words), 9 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
Cyclic amides formed from aminocarboxylic acids by the elimination of water. Lactims are the enol forms of lactams.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Lactam; Lactims; Lactim.
Where it fits in the MeSH classification
- Broader topics
- Amides; Heterocyclic Compounds, 1-Ring
- Narrower topics
- beta-Lactams; Caprolactam; Lactams, Macrocyclic; Monobactams
Related concepts
Research landscape
PubMed indexes 158,731 records tagged with the MeSH heading “Lactams” (counts retrieved 2026-10-31). 22,550 of them (14.2%) were published from 2020 onward, and the busiest period so far is through 1999 with 84,532 records.
Reviews account for 10,013 records (6.3%) and meta-analyses for 878. Randomized controlled trials number 8,077 (5.1%) as a share of all records on the topic.
Show the data
| Period | Records |
|---|---|
| through 1999 | 84,532 |
| 2000-2009 | 22,353 |
| 2010-2019 | 29,296 |
| 2020 onward | 22,550 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 10,013 | 6.3% |
| Meta-analyses | 878 | 0.6% |
| Randomized controlled trials | 8,077 | 5.1% |
Method: PubMed query "Lactams"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in drugs and chemicals
Studies of a chemical or drug can answer very different questions: what it is and how it behaves in cells and animals, how the body handles it, and whether it changes outcomes in people. Laboratory and animal findings often do not carry over to patients, and observational studies of exposures are confounded by who uses a substance and why. Nothing on this page is a recommendation to use, avoid, start or stop any substance or medicine; talk to a qualified clinician or pharmacist about your own situation. Check the dose, the species, the comparison group and whether a patient-relevant outcome was measured.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Cefazolin for Methicillin-Susceptible Staphylococcus aureus Bacteremia | 2026 | Randomized controlled trial Design not recorded in structured metadata | 10 | cc by PMID 42308484 · DOI · PMC7619232 |
| Development and validation of an interpretable machine learning-based model for predicting carbapenem-resistant Acinetobacter baumannii infection in postoperative ICU patients: a retrospective cohort study | 2026 | Research article Design not recorded in structured metadata | 5 | cc by PMID 41959558 · DOI · PMC13057271 |
| A review of the randomized clinical trial results from the Staphylococcus aureus network adaptive platform (SNAP) meticillin-susceptible (MSSA) and penicillin-susceptible (PSSA) domains and CloCeBa | 2026 | Review article Design not recorded in structured metadata | 2 | cc by PMID 42396858 · DOI · PMC13329659 |
Cefazolin for Methicillin-Susceptible Staphylococcus aureus Bacteremia [1]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundStaphylococcus aureus bacteremia is associated with high mortality.
- Closing excerpt
- ).
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (268 words)
BackgroundStaphylococcus aureus bacteremia is associated with high mortality. Whether cefazolin or an antistaphylococcal penicillin should be preferred for the treatment of methicillin-susceptible S. aureus bacteremia is unclear.MethodsIn an ongoing international Bayesian adaptive platform trial, we conducted an open-label, randomized comparison of cefazolin with an antistaphylococcal penicillin (flucloxacillin or cloxacillin) in adult patients with penicillin-resistant, methicillin-susceptible S. aureus bacteremia. The primary outcome, which was evaluated with a hierarchical Bayesian logistic-regression model, was death from any cause within 90 days after enrollment in the platform. We assessed the posterior probability of the noninferiority of cefazolin to flucloxacillin or cloxacillin (with the criterion for noninferiority prespecified as an adjusted odds ratio of ResultsThis domain of the ongoing trial was conducted between February 17, 2022, and August 7, 2024, by which time the criterion for noninferiority had been met. Mortality at 90 days among adults who could be evaluated was 15.0% (97 deaths among 645 patients) in the cefazolin group and 17.0% (109 deaths among 642 patients) in the antistaphylococcal-penicillin group (adjusted odds ratio, 0.81; 95% credible interval, 0.59 to 1.12; probability of noninferiority, 99.2%; probability of superiority, 89.8%). Acute kidney injury occurred in 92 of 660 patients (13.9%) in the cefazolin group, as compared with 127 of 648 (19.6%) in the antistaphylococcal-penicillin group (adjusted odds ratio, 0.67; 95% credible interval, 0.50 to 0.89; probability of superiority, 99.7%).ConclusionsIn patients with methicillin-susceptible S. aureus bacteremia, cefazolin was noninferior to flucloxacillin or cloxacillin with respect to 90-day mortality and was associated with a lower incidence of acute kidney injury. (Funded by the National Health and Medical Research Council and others; SNAP ClinicalTrials.gov number, NCT05137119.).
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42308484 · DOI · PMC7619232
Development and validation of an interpretable machine learning-based model for predicting carbapenem-resistant Acinetobacter baumannii infection in postoperative ICU patients: a retrospective cohort study [2]
Abstract reading summary — source excerpts
- Opening excerpt
- BackgroundCarbapenem-resistant Acinetobacter baumannii (CRAB) is a major cause of healthcare-associated infections and is associated with poor outcomes in intensive care units, particularly among postoperative patients.
- Closing excerpt
- ConclusionsThis study provides an interpretable and clinically applicable framework for early risk assessment of CRAB infection in postoperative ICU patients, supporting targeted prevention strategies and more rational antimicrobial stewardship.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (271 words)
BackgroundCarbapenem-resistant Acinetobacter baumannii (CRAB) is a major cause of healthcare-associated infections and is associated with poor outcomes in intensive care units, particularly among postoperative patients. However, predictive tools for early identification of high-risk postoperative intensive care units (ICU) patients remain scarce.MethodsWe conducted a retrospective cohort study including 2,195 postoperative ICU patients. Clinically available demographic, treatment-related, and laboratory variables were used to develop eight machine learning models. Feature selection was performed using Boruta, and model interpretability was enhanced using Shapley Additive Explanations (SHAP) analysis. Model performance was evaluated in an independent test set using the area under the receiver operating characteristic curve (AUC), with sensitivity analyses performed using reduced feature sets.ResultsAmong 2,195 postoperative ICU patients, 694 (31.6%) developed CRAB infection. Patients with CRAB infection had significantly longer ICU stays, greater exposure to invasive procedures, higher antimicrobial use, and worse laboratory profiles than non-infected patients. Using 19 features selected by the Boruta algorithm, all eight machine learning models achieved good discrimination in the test set (AUC > 0.83). Gradient Boosting demonstrated the best overall performance, with an AUC of 0.867 (95% CI: 0.836-0.892), good calibration, and the highest net clinical benefit. SHAP analysis identified duration of mechanical ventilation, central venous catheterization, ICU length of stay (LOS), and carbapenem exposure as the most influential predictors. Sensitivity analyses showed that models using only the top 10 or top 5 SHAP-ranked features achieved performance comparable to the full model, supporting the feasibility of feature reduction for clinical application.ConclusionsThis study provides an interpretable and clinically applicable framework for early risk assessment of CRAB infection in postoperative ICU patients, supporting targeted prevention strategies and more rational antimicrobial stewardship.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 41959558 · DOI · PMC13057271
A review of the randomized clinical trial results from the Staphylococcus aureus network adaptive platform (SNAP) meticillin-susceptible (MSSA) and penicillin-susceptible (PSSA) domains and CloCeBa [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Current guidelines for the management of meticillin-susceptible Staphyloccocus aureus bloodstream infection/bacteraemia (SAB) recommend intravenous (flu)cloxacillin as the first-line treatment.
- Closing excerpt
- We discuss how this new evidence might be combined with our existing knowledge and the results of the CloCeBa trial to guide us how to appropriately manage our patients.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (148 words)
Current guidelines for the management of meticillin-susceptible Staphyloccocus aureus bloodstream infection/bacteraemia (SAB) recommend intravenous (flu)cloxacillin as the first-line treatment. This is based on decades of clinical practice. The high acute kidney injury rates seen with (flu)cloxacillin in the recently published SNAP trial, which is the largest randomized clinical trial ever in S. aureus bacteraemia (SAB), shows us the need to regularly test and question our usual clinical practice. Acute kidney injury is common in SAB when high doses of (flu)cloxacillin are used. The contribution of (flu)cloxacillin to developing or exacerbating acute kidney injury is likely to have been under recognized until now. Caution needs to be taken with (flu)cloxacillin. Cefazolin provides a safer and equally efficacious treatment for SAB. We discuss how this new evidence might be combined with our existing knowledge and the results of the CloCeBa trial to guide us how to appropriately manage our patients.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42396858 · DOI · PMC13329659
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Systematic review and meta-analysis of mortality of patients infected with carbapenem-resistant Klebsiella pneumoniae [4]
- Research article Beta lactam monotherapy versus beta lactam-aminoglycoside combination therapy for sepsis in immunocompetent patients: systematic review and meta-analysis of randomised trials [5]
- Research article Prolonged versus short-term intravenous infusion of antipseudomonal β-lactams for patients with sepsis: a systematic review and meta-analysis of randomised trials [6]
- Research article Carbapenem resistance and mortality in patients with Acinetobacter baumannii infection: systematic review and meta-analysis [7]
- Research article Clinical outcomes following inpatient penicillin allergy testing: A systematic review and meta-analysis [8]
- Research article A Systematic Review and Meta-analyses of the Clinical Epidemiology of Carbapenem-Resistant Enterobacteriaceae [9]
References
- Staphylococcus aureus Network Adaptive Platform (SNAP) Trial Group, Lee TC, Barina LA, Walls G, Goodman AL, Yahav D, et al.. Cefazolin for Methicillin-Susceptible Staphylococcus aureus Bacteremia. . 2026. PMID 42308484 · DOI · PMC7619232
- Gao Y, Gu G, Wang R, Jia C, Zhao F, Cao D, et al.. Development and validation of an interpretable machine learning-based model for predicting carbapenem-resistant Acinetobacter baumannii infection in postoperative ICU patients: a retrospective cohort study. . 2026. PMID 41959558 · DOI · PMC13057271
- Goodman AL, Easom N, Bielopolski D, Sutherland RK, Marks M, Hensgens MPM, et al.. A review of the randomized clinical trial results from the Staphylococcus aureus network adaptive platform (SNAP) meticillin-susceptible (MSSA) and penicillin-susceptible (PSSA) domains and CloCeBa. . 2026. PMID 42396858 · DOI · PMC13329659
- Xu L, Sun X, Ma X. Systematic review and meta-analysis of mortality of patients infected with carbapenem-resistant Klebsiella pneumoniae. Ann Clin Microbiol Antimicrob. 2017. PMID 28356109 · DOI · PMC5371217
- Paul M, Benuri-Silbiger I, Soares-Weiser K, Leibovici L. Beta lactam monotherapy versus beta lactam-aminoglycoside combination therapy for sepsis in immunocompetent patients: systematic review and meta-analysis of randomised trials. BMJ. 2004. PMID 14996699 · DOI · PMC381218
- Vardakas KZ, Voulgaris GL, Maliaros A, Samonis G, Falagas ME. Prolonged versus short-term intravenous infusion of antipseudomonal β-lactams for patients with sepsis: a systematic review and meta-analysis of randomised trials. Lancet Infect Dis. 2018. PMID 29102324 · DOI
- Lemos EV, de la Hoz FP, Einarson TR, McGhan WF, Quevedo E, Castañeda C, et al.. Carbapenem resistance and mortality in patients with Acinetobacter baumannii infection: systematic review and meta-analysis. Clin Microbiol Infect. 2014. PMID 24131374 · DOI
- Sacco KA, Bates A, Brigham TJ, Imam JS, Burton MC. Clinical outcomes following inpatient penicillin allergy testing: A systematic review and meta-analysis. Allergy. 2017. PMID 28370003 · DOI
- van Loon K, Voor In 't Holt AF, Vos MC. A Systematic Review and Meta-analyses of the Clinical Epidemiology of Carbapenem-Resistant Enterobacteriaceae. Antimicrob Agents Chemother. 2018. PMID 29038269 · DOI · PMC5740327
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-31.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.