bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/726000

In vitro Evaluation of Various Antimicrobials against Field Mycoplasma gallisepticum and Mycoplasma synoviae Isolates in Egypt

Abd El-Hamid, M. I.·Awad, N. F.·Abo-Shama, U.·H, Y. M.·Abdel-Rahman, M. A.·Hetta, H. F.·Abdelaziz, A. M.
View original source ↗Export metadata ↓

Abstract

Among many avian mycoplasmas, Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) are recognized as the main etiological agents of respiratory diseases and infectious synovitis in chickens and turkeys causing tremendous economic losses worldwide. Therefore, proper treatment is promoted for the control of these diseases. This study was the first in Egypt to evaluate the in vitro efficacy of various antimicrobials against field MG and MS isolates recovered from chicken and turkey flocks using both conventional microdilution and quantitative real-time PCR (qRT-PCR) assays. Totally, 47 mycoplasma isolates were recovered from 160 collected tracheal samples (29.4%). Of these, 44 MG (27.5%) and 3 MS (1.9%) were identified using conventional and molecular assays. The in vitro susceptibilities of 4 representative mycoplasma isolates (3 MG and one MS) to 8 antibiotics and 4 essential oils were investigated. The tested isolates showed various susceptibilities to tested antimicrobials. Toldin CRD, followed by clove, cumin and cinnamon oils were commonly effective against both MG and MS clinical isolates with MIC values ranging from 0.49 to 15.63 {micro}g/mL. Similarly, tylvalosin was the most active antibiotic against MG and MS isolates with the lowest MIC values (0.015-0.03 {micro}g/mL). DNA copies of both MG mgc2 and MS vlhA genes were markedly decreased upon treatment with majority of tested antimicrobials confirming their effectiveness as was also evaluated by conventional MIC results. In conclusion, Toldin CRD and tylvalosin were found to be the most effective antimicrobials in this study, which will contribute in controlling avian mycoplasma infections.\n\nAuthor SummaryAvian mycoplasmosis is considered as one of the most prominent economic problems in the commercial poultry industry worldwide. Antimicrobial therapy is the most effective tool for treatment of mycoplasmas. Owing to the side effects of antibiotics and the development of resistance to the currently used drugs, an increased emphasis on the use of alternative antimicrobials is of utmost importance. Here, we evaluate the in vitro inhibitory effects of some essential oils and various commercial antibiotics against Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) field isolates using micro-broth dilution method and qRT-PCR assays. We found that toldin CRD, followed by clove, cumin and cinnamon oils were effective against both MG and MS clinical isolates. Similarly, tylvalosin was the most active antibiotic against MG and MS isolates. We also found that DNA copies of both MG mgc2 and MS vlhA genes were markedly decreased upon treatment with majority of tested antimicrobials. Our study provides new insights into the control of avian mycoplasma infections.

Source connections

Explore related subjects

microbiologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Abd El-Hamid, M. I., Awad, N. F., Abo-Shama, U., H, Y. M., Abdel-Rahman, M. A., Hetta, H. F., Abdelaziz, A. M.. 2019-08-05. In vitro Evaluation of Various Antimicrobials against Field Mycoplasma gallisepticum and Mycoplasma synoviae Isolates in Egypt. https://doi.org/10.1101/726000

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Reverse Transcription Loop-Mediated Isothermal Amplification Combined with Lateral Flow Assay (RT-LAMP-LFA) for Rapid Detection of the 2026 Bundibugyo Virus (BDBV) Outbreak Strain

Making accurate diagnosis is a critical first step in patient management and control for emerging and re-emerging disease outbreaks. Bundibugyo virus (BDBV) is a filovirus that causes Ebola disease, and the 2026 outbreak highlights the need for rapid diagnostic approaches that can be deployed in settings with limited laboratory infrastructure. Here, we developed a reverse transcription loop-mediated isothermal amplification-lateral flow assay (RT-LAMP-LFA) for rapid detection of the 2026 BDBV outbreak strain. LAMP primers were designed based on the genome sequence of the 2026 outbreak strain, and the conservation of the primer binding sites among all available 2026 outbreak genomes was confirmed in silico. LAMP primers were evaluated for analytical specificity and sensitivity using in vitro-transcribed RNA (ivtRNA) from BDBV and other filoviruses, as well as RNA derived from arboviruses and mammalian cells. Amplification products were detected using a Chromatography-Printed Array Strip (C-PAS) lateral flow platform. The newly designed primers specifically detected the presence of BDBV RNA without nonspecific amplification of the other viral or cellular RNA samples tested. Consistent amplification was observed down to 103 copies per reaction. In addition, BDBV viral RNA was successfully amplified, and the amplification products were detected using C-PAS, with the total workflow being completed within 25 min. These findings demonstrate the analytical specificity and sensitivity of the developed RT-LAMP-LFA assay and its compatibility with rapid visual lateral flow detection, supporting its potential application as a point-of-care approach for BDBV detection.

microbiology↗
bioRxiv2026

Divergent methane production and microbial community responses to carbon enrichment in freshwater wetland sediments

Methane (CH4) accumulation in wetland sediments reflects interactions among organic matter, sediment chemistry, and microbial communities. We combined depth-resolved field characterization across four wetland habitats in northern Israel with complementary incubations to examine methane accumulation and responses to labile-carbon enrichment. Sediment cores were characterized using Rock-Eval analysis, porewater chemistry, oxygen profiling at three sites, and mcrA amplicon sequencing. High CH4 concentrations occurred under contrasting conditions: Ein Nimfit (EN) contained approximately 12% total organic carbon and reached 2.1 mM CH4, whereas Ein Afek site EA2 contained approximately 5% carbon and accumulated 0.7-1.7 mM CH4. Both showed sulfate depletion, but EN exhibited pronounced sulfide accumulation, whereas EA2 showed greater dissolved iron and nutrient enrichment. Their classified methanogenic assemblages also differed. EA1 remained methane poor despite increasing carbon content with depth, while EA3 combined low carbon content and CH4 accumulation with detectable methanogens and lower methanogenic diversity. In a 36-day bottle experiments using sediments from two of the four wetland habitats, sucrose-amended EA3 exhibited a transient maximum of 18.8 mmol collected CH4 kg-1 wet sediment during Days 22-29, whereas EN reached its highest collected amount during Days 29-36. Methane proportions increased before the large output increase in EA3 but remained comparatively stable and high in EN. Soluble chemical oxygen demand trajectories and microbial community changes also differed. These findings identify distinct biogeochemical settings supporting methane accumulation and demonstrate methanogenic potential in low-CH4 sediment, emphasizing the complementary information provided by field profiles, microbial characterization, and exploratory enrichment experiments.

microbiology↗
bioRxiv2026

The absence of microbiome in germ-free mice exacerbates the pathogenicity of mouse-adapted SARS-CoV-2 MA10

Germ-free mice, which are devoid of microbiota, provide a powerful system to define the contribution of the microbiome to host responses during infection. Severe COVID-19 outcomes are associated with multiple comorbidities that are themselves characterized by microbiome dysbiosis; however, the causal role of the microbiota in SARS-CoV-2 pathogenesis remains poorly understood. Here, we use germ-free mouse models to evaluate the impact of the microbiome on disease severity following infection with mouse-adapted SARS-CoV-2 MA10. Comparison with conventionally housed mice revealed that the absence of the microbiome markedly exacerbates SARS-CoV-2-induced disease in both C57BL/6 and Swiss Webster backgrounds. Germ-free mice exhibited greater weight loss, impaired lung function, worsened pulmonary pathology, and pronounced alterations in circulating cytokine and chemokine profiles compared with conventional controls. These findings show that resident microbiota limit SARS-CoV-2 pathogenicity and establish germ-free COVID-19 models as a powerful platform to identify protective microbial taxa and microbiota-based interventions to reduce severe disease.

microbiology↗