Effect of Mycoplasma synoviae strains isolated from the respiratory and reproductive tracts of chicken on SPF chicken embryos

Mycoplasma synoviae (MS) infections in poultry are an important epidemiological and economic problem in poultry production all over the world. The differences between M. synoviae strains are related to the pathogenicity and the course of the disease. In recent years, the pathogenicity of M. synoviae strains has increased, and some of them are capable of causing serious infections. Both horizontal and vertical transmission routes play an important role in MS infection in flocks. The aim of the study was to determine the impact of infection with selected MS strains obtained from chickens showing a clinical form of MS infection on SPF chicken embryos. Ten strains of M. synoviae were used for this purpose. The strains were isolated from the respiratory tract and the oviduct of chickens with symptoms typical of infection with this pathogen. Genetic material isolated from liquid cultures of these strains was confirmed by molecular (PCR and LAMP) and microbiological methods. The selected M. synoviae strains belonged to six different genotypes. Significant differences in virulence between the strains were demonstrated. In nine infected groups of embryos, M. synoviae strains caused weight loss, and in seven groups they produced anatomopathological changes characteristic of mycoplasma infections. The most pathogenic for SPF chicken embryos turned out to be strains characterized as genotype F isolated from the chicken oviduct and strains of genotype C isolated from the respiratory tract. One strain of genotype H isolated from the respiratory tract showed no pathogenic effect on SPF chicken embryos. The study showed that infections with M. synoviae can have a significant impact on the production of chicken chicks in commercial hatcheries and the economy of the poultry industry.

Antibiotic resistance of Mycoplasma Synoviae strains isolated in China from 2016 to 2019

Background In the past decade, Mycoplasma synoviae (M. synoviae) infection has become widely prevalent in China, has caused serious economic losses and has become one of the most important diseases in the chicken industry. Medication is a general approach for the control of M. synoviae infection, but antibiotics are sometimes ineffective in clinical practice. To investigate the sensitivity of M. synoviae to antimicrobials commonly used in the treatment of M. synoviae infection, the antibiotic susceptibility of 32 M. synoviae strains isolated from China from 2016 to 2019 were determined using the minimum inhibitory concentration (MIC) method. Results All isolates had low MIC values for the combination of lincomycin and spectinomycin, pleuromutilin, and macrolides. However, the M. synoviae isolates displayed variance in MICs for doxycycline hydrochloride with a range of 0.25 to 8 μg/mL, and oxytetracycline hydrochloride with a range of 0.5 to 8 μg/mL. Three and one M. synoviae isolates showed intermediate MIC values to doxycycline hydrochloride and oxytetracycline hydrochloride, respectively. High MIC values for enrofloxacin were detected in all isolates with MICs ranging from 4 to 32 μg/mL. Furthermore, comparison of the parC QRDR identified a mutation at nucleotide position 254 (C254T) resulting in a Thr 85 Ile amino acid change in all M. synoviae isolates and the reference strain ATCC 25204 being resistant to enrofloxacin. Moreover, mutations at Glu 804 Gly and Thr 686 Ala of gyrA QRDR were identified in all M. synoviae isolates and ATCC 25204. The mutation in the QRDR of the parE gene resulted in amino acid changes at positions 197 (Pro to Ser) in 27/32 M. synoviae isolates. Conclusion Three nonsynonymous mutations in gyrA and parE were first identified to be related to enrofloxacin resistance. Our results showed that M. synoviae resistance to enrofloxacin is widespread.

Complete Genome Sequencing of the Attenuated Strain Mycoplasma synoviae 5-9

Here, we present the complete genome sequence of Mycoplasma synoviae strain 5-9. Strain 5-9 was attenuated by chemical mutagenesis from a field strain isolated from egg breeders in Ningxia, China. It was completely sequenced and its genome annotated; it is presented with the relevant data as a potential vaccine candidate.

Pharmacokinetic/Pharmacodynamic Modeling of Spiramycin against Mycoplasma synoviae in Chickens

This research aimed to assess the pharmacokinetics/pharmacodynamics (PK/PD) and tissue residues of spiramycin in chickens. The PK of spiramycin were determined in 12 chickens using a parallel study design in which each group of chickens (n = 6) received a single dose of spiramycin at 17 mg/kg intravenously (IV) or orally. Plasma samples were collected at assigned times for up to 48 h to measure spiramycin concentrations. Additionally, a tissue depletion study was performed in 42 chickens receiving spiramycin at 17 mg/kg/day orally for 7 days. The area under the plasma concentration–time curve values were 29.94 ± 4.74 and 23.11 ± 1.83 µg*h/mL after IV and oral administrations, respectively. The oral bioavailability was 77.18%. The computed withdrawal periods of spiramycin were 11, 10, and 7 days for liver, muscle, and skin and fat, respectively. The minimum inhibitory concentration for spiramycin against Mycoplasma synoviae (M. synoviae) strain 1853 was 0.0625 µg/mL. Using the PK/PD integration, the appropriate oral dose of spiramycin against M. synoviae was estimated to be 15.6 mg/kg. Thus, we recommend an oral dose of 15.6 mg spiramycin/kg against M. synoviae in chickens and a withdrawal period of 11 days following oral treatment with 17 mg spiramycin/kg/day for 7 days.

Genome Analysis of Nicotinamide Adenine Dinucleotide-Independent Mycoplasma synoviae Isolates From Korea

Mycoplasma synoviae (MS) is an avian pathogen that causes respiratory disease, infectious synovitis, and eggshell apex abnormalities in chickens. Nicotinamide adenine dinucleotide (NAD)-independent MS was first reported in 1975. Despite the atypical traits of NAD-independent MS, its independence from NAD has not been studied. In this study, we isolated five NAD-independent strains from Korea and assembled their genomes using sequencing reads obtained from Illumina and Oxford Nanopore Technology platforms. The assembled genomes were compared with the genomes of MS-H vaccine strain and type strain WVU1853. We found that the coding sequences of nicotinate phosphoribosyltransferase and glycerol-3-phosphate acyltransferase, and a unique coding sequence were present only in the genomes of NAD-independent isolates.