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: 4 complete abstracts (693 words), 10 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
An antibiotic first isolated from cultures of Streptomyces venequelae in 1947 but now produced synthetically. It has a relatively simple structure and was the first broad-spectrum antibiotic to be discovered. It acts by interfering with bacterial protein synthesis and is mainly bacteriostatic. (From Martindale, The Extra Pharmacopoeia, 29th ed, p106)
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: Cloranfenicol; Kloramfenikol; Chloromycetin; Chlornitromycin; Chlorocid; Detreomycin; Ophthochlor; Syntomycin.
Where it fits in the MeSH classification
- Broader topics
- Propylene Glycols; Nitrobenzenes
- Narrower topics
- Thiamphenicol
Research landscape
PubMed indexes 21,155 records tagged with the MeSH heading “Chloramphenicol” (counts retrieved 2026-10-31). 1,121 of them (5.3%) were published from 2020 onward, and the busiest period so far is through 1999 with 17,521 records.
Reviews account for 686 records (3.2%) and meta-analyses for 16. Randomized controlled trials number 265 (1.3%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.
Show the data
| Period | Records |
|---|---|
| through 1999 | 17,521 |
| 2000-2009 | 1,149 |
| 2010-2019 | 1,364 |
| 2020 onward | 1,121 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 686 | 3.2% |
| Meta-analyses | 16 | 0.1% |
| Randomized controlled trials | 265 | 1.3% |
Method: PubMed query "Chloramphenicol"[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 |
|---|---|---|---|---|
| Azithromycin and Chloramphenicol Diminish Neutrophil Extracellular Traps (NETs) Release | 2017 | Research article Design not recorded in structured metadata | 81 | cc by PMID 29292737 · DOI · PMC5751268 |
| New insights into chloramphenicol biosynthesis in Streptomyces venezuelae ATCC 10712 | 2014 | Research article Design not recorded in structured metadata | 69 | cc by PMID 25267678 · DOI · PMC4249514 |
| Prevalence and Abundance of Florfenicol and Linezolid Resistance Genes in Soils Adjacent to Swine Feedlots | 2016 | Research article Design not recorded in structured metadata | 65 | cc by PMID 27573068 · DOI · PMC5004119 |
| Selection for florfenicol resistance at sub-MIC concentrations in Pasteurella multocida | 2025 | Research article Design not recorded in structured metadata | 2 | cc by PMID 40554597 · DOI · PMC12186936 |
Azithromycin and Chloramphenicol Diminish Neutrophil Extracellular Traps (NETs) Release [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Neutrophils are one of the first cells to arrive at the site of infection, where they apply several strategies to kill pathogens: degranulation, respiratory burst, phagocytosis, and release of neutrophil extracellular traps (NETs).
- Closing excerpt
- It can be concluded that antibiotics modulate the ability of neutrophils to release NETs influencing human innate immunity.
- 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 (203 words)
Neutrophils are one of the first cells to arrive at the site of infection, where they apply several strategies to kill pathogens: degranulation, respiratory burst, phagocytosis, and release of neutrophil extracellular traps (NETs). Antibiotics have an immunomodulating effect, and they can influence the properties of numerous immune cells, including neutrophils. The aim of this study was to investigate the effects of azithromycin and chloramphenicol on degranulation, apoptosis, respiratory burst, and the release of NETs by neutrophils. Neutrophils were isolated from healthy donors by density-gradient centrifugation method and incubated for 1 h with the studied antibiotics at different concentrations (0.5, 10 and 50 μg/mL-azithromycin and 10 and 50 μg/mL-chloramphenicol). Next, NET release was induced by a 3 h incubation with 100 nM phorbol 12-myristate 13-acetate (PMA). Amount of extracellular DNA was quantified by fluorometry, and NETs were visualized by immunofluorescent microscopy. Degranulation, apoptosis and respiratory burst were assessed by flow cytometry. We found that pretreatment of neutrophils with azithromycin and chloramphenicol decreases the release of NETs. Moreover, azithromycin showed a concentration-dependent effect on respiratory burst in neutrophils. Chloramphenicol did not affect degranulation, apoptosis nor respiratory burst. It can be concluded that antibiotics modulate the ability of neutrophils to release NETs influencing human innate immunity.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 29292737 · DOI · PMC5751268
New insights into chloramphenicol biosynthesis in Streptomyces venezuelae ATCC 10712 [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Comparative genome analysis revealed seven uncharacterized genes, sven0909 to sven0915, adjacent to the previously identified chloramphenicol biosynthetic gene cluster (sven0916-sven0928) of Streptomyces venezuelae strain ATCC 10712 that was absent in a closely related Streptomyces strain that does not produce chloramphenicol.
- Closing excerpt
- This has allowed us to propose an updated and revised version of the chloramphenicol biosynthetic pathway.
- 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 (155 words)
Comparative genome analysis revealed seven uncharacterized genes, sven0909 to sven0915, adjacent to the previously identified chloramphenicol biosynthetic gene cluster (sven0916-sven0928) of Streptomyces venezuelae strain ATCC 10712 that was absent in a closely related Streptomyces strain that does not produce chloramphenicol. Transcriptional analysis suggested that three of these genes might be involved in chloramphenicol production, a prediction confirmed by the construction of deletion mutants. These three genes encode a cluster-associated transcriptional activator (Sven0913), a phosphopantetheinyl transferase (Sven0914), and a Na(+)/H(+) antiporter (Sven0915). Bioinformatic analysis also revealed the presence of a previously undetected gene, sven0925, embedded within the chloramphenicol biosynthetic gene cluster that appears to encode an acyl carrier protein, bringing the number of new genes likely to be involved in chloramphenicol production to four. Microarray experiments and synteny comparisons also suggest that sven0929 is part of the biosynthetic gene cluster. This has allowed us to propose an updated and revised version of the chloramphenicol biosynthetic pathway.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 25267678 · DOI · PMC4249514
Prevalence and Abundance of Florfenicol and Linezolid Resistance Genes in Soils Adjacent to Swine Feedlots [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Florfenicol is extensively used in livestock to prevent or cure bacterial infections.
- Closing excerpt
- It appears that amount of florfenicol used on swine farms and the spreading of soils with swine waste could promote the prevalence and abundance of FRGs, including the linezolid resistance genes cfr and optrA, in adjacent soils, and agricultural application of swine manure with florfenicol may have caused a residual level of florfenicol in the soils.
- 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 (188 words)
Florfenicol is extensively used in livestock to prevent or cure bacterial infections. However, it is not known whether the administration of florfenicol has resulted in the emergence and dissemination of florfenicol resistance genes (FRGs, including fexA, fexB, cfr, optrA, floR, and pexA) in microbial populations in surrounding farm environments. Here we collected soil samples for the detection of FRGs and the residue of florfenicol from six swine farms with the record of florfenicol usage. Quantitative polymerase chain reaction and metagenomic sequencing revealed a significantly higher relative abundance of FRGs in the soils adjacent to the three swine farms where florfenicol was heavily used compared with the other sites. Meanwhile, the detectable levels of florfenicol were also identified in soils from two of these three farms using ultra-performance liquid chromatography tandem mass spectrometry. It appears that amount of florfenicol used on swine farms and the spreading of soils with swine waste could promote the prevalence and abundance of FRGs, including the linezolid resistance genes cfr and optrA, in adjacent soils, and agricultural application of swine manure with florfenicol may have caused a residual level of florfenicol in the soils.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 27573068 · DOI · PMC5004119
Selection for florfenicol resistance at sub-MIC concentrations in Pasteurella multocida [4]
Abstract reading summary — source excerpts
- Opening excerpt
- Antimicrobial resistance is a global threat to both human and animal health, and transfer of resistance between these spheres is recognised as a key concern for all species.
- Closing excerpt
- These results have important implications for antimicrobial resistance selection at sub-inhibitory concentrations, method development for within-species differentiation in novel bacterial species, and application to policy regarding antimicrobial contamination in animal-feed.
- 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 (147 words)
Antimicrobial resistance is a global threat to both human and animal health, and transfer of resistance between these spheres is recognised as a key concern for all species. Selection for resistance at sub-inhibitory antimicrobial concentrations has been characterised for some bacteria-antimicrobial combinations but there is little data from non-laboratory strains, and veterinary antimicrobials and bacterial species. Here, we demonstrate a minimum selective concentration of 0.06 mg/L (1/6 xMIC) for florfenicol in wild-type Pasteurella multocida, through competition experiments between a susceptible strain and a floR-resistant mutant. We also show that sub-inhibitory concentrations of florfenicol do not appear to significantly select for de novo resistance in P. multocida and present the challenges with adapting experimental protocols between bacterial species. These results have important implications for antimicrobial resistance selection at sub-inhibitory concentrations, method development for within-species differentiation in novel bacterial species, and application to policy regarding antimicrobial contamination in animal-feed.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 40554597 · DOI · PMC12186936
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 Molecular basis of bacterial resistance to chloramphenicol and florfenicol [5]
- Research article O-Acetyltransferases for chloramphenicol and other natural products [6]
- Research article Antibiotics exposure and health risks: chloramphenicol [7]
- Research article Lincosamides, Streptogramins, Phenicols, and Pleuromutilins: Mode of Action and Mechanisms of Resistance [8]
- Research article Aptasensors as the future of antibiotics test kits-a case study of the aptamer application in the chloramphenicol detection [9]
- Research article Chloramphenicol: a review [10]
References
- Bystrzycka W, Manda-Handzlik A, Sieczkowska S, Moskalik A, Demkow U, Ciepiela O. Azithromycin and Chloramphenicol Diminish Neutrophil Extracellular Traps (NETs) Release. . 2017. PMID 29292737 · DOI · PMC5751268
- Fernández-Martínez LT, Borsetto C, Gomez-Escribano JP, Bibb MJ, Al-Bassam MM, Chandra G, et al.. New insights into chloramphenicol biosynthesis in Streptomyces venezuelae ATCC 10712. . 2014. PMID 25267678 · DOI · PMC4249514
- Zhao Q, Wang Y, Wang S, Wang Z, Du XD, Jiang H, et al.. Prevalence and Abundance of Florfenicol and Linezolid Resistance Genes in Soils Adjacent to Swine Feedlots. . 2016. PMID 27573068 · DOI · PMC5004119
- Hughes A, Pelligand L, Andersson DI, Mead A. Selection for florfenicol resistance at sub-MIC concentrations in Pasteurella multocida. . 2025. PMID 40554597 · DOI · PMC12186936
- Schwarz S, Kehrenberg C, Doublet B, Cloeckaert A. Molecular basis of bacterial resistance to chloramphenicol and florfenicol. FEMS Microbiol Rev. 2004. PMID 15539072 · DOI
- Murray IA, Shaw WV. O-Acetyltransferases for chloramphenicol and other natural products. Antimicrob Agents Chemother. 1997. PMID 8980745 · DOI · PMC163650
- Hanekamp JC, Bast A. Antibiotics exposure and health risks: chloramphenicol. Environ Toxicol Pharmacol. 2015. PMID 25528412 · DOI
- Schwarz S, Shen J, Kadlec K, Wang Y, Brenner Michael G, Feßler AT, et al.. Lincosamides, Streptogramins, Phenicols, and Pleuromutilins: Mode of Action and Mechanisms of Resistance. Cold Spring Harb Perspect Med. 2016. PMID 27549310 · DOI · PMC5088508
- Khoshbin Z, Verdian A, Housaindokht MR, Izadyar M, Rouhbakhsh Z. Aptasensors as the future of antibiotics test kits-a case study of the aptamer application in the chloramphenicol detection. Biosens Bioelectron. 2018. PMID 30268964 · DOI
- Balbi HJ. Chloramphenicol: a review. Pediatr Rev. 2004. PMID 15286274 · DOI
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.
See how EvidenceLib is built. Spotted an error? Email support@evidencehelix.com.
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.