Novel model integrating computed tomography-based image markers with genetic markers for discriminating radiation pneumonitis in patients with unresectable stage III non-small cell lung cancer receiving radiotherapy: a retrospective multi-center radiogenomics study.

BACKGROUND: Chemoradiotherapy is a critical treatment for patients with locally advanced and unresectable non-small cell lung cancer (NSCLC), and it is essential to identify high-risk patients as early as possible owing to the high incidence of radiation pneumonitis (RP). Increasing attention is being paid to the effects of endogenous factors for RP. This study aimed to investigate the value of computed tomography (CT)-based radiomics combined with genomics in analyzing the risk of grade ≥ 2 RP in unresectable stage III NSCLC. METHODS: In this retrospective multi-center observational study, 100 patients with unresectable stage III NSCLC who were treated with chemoradiotherapy were analyzed. Radiomics features of the entire lung were extracted from pre-radiotherapy CT images. The least absolute shrinkage and selection operator algorithm was used for optimal feature selection to calculate the Rad-score for predicting grade ≥ 2 RP. Genomic DNA was extracted from formalin-fixed paraffin-embedded pretreatment biopsy tissues. Univariate and multivariate logistic regression analyses were performed to identify predictors of RP for model development. The area under the receiver operating characteristic curve was used to evaluate the predictive capacity of the model. Statistical comparisons of the area under the curve values between different models were performed using the DeLong test. Calibration and decision curves were used to demonstrate discriminatory and clinical benefit ratios, respectively. RESULTS: The Rad-score was constructed from nine radiomic features to predict grade ≥ 2 RP. Multivariate analysis demonstrated that histology, Rad-score, and XRCC1 (rs25487) allele mutation were independent high-risk factors correlated with RP. The area under the curve of the integrated model combining clinical factors, radiomics, and genomics was significantly higher than that of any single model (0.827 versus 0.594, 0.738, or 0.641). Calibration and decision curve analyses confirmed the satisfactory clinical feasibility and utility of the nomogram. CONCLUSION: Histology, Rad-score, and XRCC1 (rs25487) allele mutation could predict grade ≥ 2 RP in patients with locally advanced unresectable NSCLC after chemoradiotherapy, and the integrated model combining clinical factors, radiomics, and genomics demonstrated the best predictive efficacy.

Characteristics and predictors of low-grade renal artery stenosis in female patients with CKD.

AIM: Renal artery stenosis (RAS) is an important cause of chronic kidney disease (CKD). The main purpose of this study was to explore the clinical characteristics and predictors of low-grade RAS in female patients with CKD. METHODS: One hundred and five female CKD patients from Huadong Hospital affiliated with Fudan University who underwent 3 T non-contrast renal artery magnetic resonance angiography (MRA) were analyzed. Basic statistics methods were used in the study, such as independent-sample t test,non-parametric test, binary logistic regression analysis and ROC analysis. RESULTS: In this cross-sectional study, there were 50 patients with RAS and 55 without RAS (47.6% versus 52.4%). Binary logistic regression analysis demonstrated that low-level ALB and lymphocyte count, high-level SP, BUN and NLR were independent risk factors for low-grade RAS in female patients with CKD. ROC analysis indicated that eGFR, FeNa and UBCR, ALB, lymphocyte count and NLR had the best predictive value for low-grade RAS, especially eGFR with a sensitivity of 65.50% and specificity of 72.00% and FeNa with a sensitivity of 71.10% and specificity of 72.20% and BUCR with a sensitivity of 71.10% and specificity of 68.10%. CONCLUSION: In female patients with CKD, FeNa, eGFR, ALB, UBCR, lymphocyte count and NLR may be good predictors of low-grade RAS, especially eGFR, FeNa and BUCR.

Luteolin increases susceptibility to macrolides by inhibiting MsrA efflux pump in Trueperella pyogenes.

Trueperella pyogenes (T. pyogenes) is an opportunistic pathogen associated with a variety of diseases in many domestic animals. Therapeutic treatment options for T. pyogenes infections are becoming limited due to antimicrobial resistance, in which efflux pumps play an important role. This study aims to evaluate the inhibitory activity of luteolin, a natural flavonoid, on the MsrA efflux pump and investigate its mechanism. The results of antimicrobial susceptibility testing indicated that the susceptibility of msrA-positive T. pyogenes isolates to six macrolides increased after luteolin treatment, while the susceptibility of msrA-negative isolates showed no change after luteolin treatment. It is suspected that luteolin may increase the susceptibility of T. pyogenes isolates by inhibiting MsrA activity. After 1/2 MIC luteolin treatment for 36 h, the transcription level of the msrA gene and the expression level of the MsrA protein decreased by 55.0-97.7% and 36.5-71.5%, respectively. The results of an affinity test showed that the equilibrium dissociation constant (KD) of luteolin and MsrA was 6.462 × 10-5 M, and hydrogen bonding was predominant in the interaction of luteolin and MsrA. Luteolin may inhibit the ATPase activity of the MsrA protein, resulting in its lack of an energy source. The current study illustrates the effect of luteolin on MsrA in T. pyogenes isolates and provides insight into the development of luteolin as an innovative agent in combating infections caused by antimicrobial-resistant bacteria.

Molecular Basis for Luteolin as a Natural TatD DNase Inhibitor in Trueperella pyogenes.

TatD960 and TatD825 are DNases that contribute to biofilm formation and virulence in Trueperella pyogenes (T. pyogenes). Luteolin is a natural flavonoid commonly found in plants that exhibits antimicrobial capacity. Our study aims to investigate the effects of luteolin on TatD DNases as a natural inhibitor. In this research, the expression of tatD genes and TatD proteins in T. pyogenes treated with luteolin was detected, and then the effect of luteolin on the hydrolysis of DNA by TatD DNases was analyzed using agarose gel electrophoresis. Moreover, the interactions between luteolin and TatD DNases were tested using surface plasmon resonance (SPR) assays and molecular docking analysis. After 1/2 MIC luteolin treatment, the transcription of tatD genes and expression of TatD proteins appeared to be reduced in 80-90% of T. pyogenes (n = 20). The gel assay revealed that luteolin can inhibit the activity of TatD DNases. The SPR assay showed that the KD values of luteolin to TatD960 and TatD825 were 6.268 × 10-6 M and 5.654 × 10-6 M, respectively. We found through molecular docking that hydrogen bonding is predominant in the interaction of luteolin and TatD DNases. Our data indicate that luteolin inhibited the ability of TatD DNases by decreasing their binding to DNA. The current study provides an insight into the development of luteolin as a DNase inhibitor in preventing biofilm formation and virulence in T. pyogenes.

Mineralogical characteristics and photocatalytic properties of natural sphalerite from China.

Different natural sphalerites have a range of photocatalytic properties that can potentially be exploited for environmental remediation purposes. To develop value in the exploitation of sphalerite, samples were collected from 19 ore deposits in China and characterized for their mineralogical and photocatalytic properties. X-ray diffraction (XRD) and electron probe micro analysis (EPMA) measurements indicated that all the natural sphalerites from various localities crystallized in cubic phases with various chemical compositions. The substitution of Fe for Zn ranged from 0.235% to 14.826% by weight, Mn from 0.004% to 4.868%, Cu from 0.009% to 5.529% and Cd from 0.133% to 1.576%. As Fe became more abundant, the color of natural sphalerite darkened, becoming almost black; and higher Fe content was associated with stronger visible light absorption. Photoluminescence spectra showed emission mainly related to S-vacancies and progressively decreasing fluorescence intensity with increasing Fe content. Tests of the photocatalytic degradation of methyl orange indicated that the sample with the highest Cd content but moderate Fe content had the highest photocatalytic activity. Specifically, the degradation of Methyl Orange (30 mg/L) attained 82.11% efficiency under visible light irradiation for 4 hr of natural sphalerite with 4.262% Fe and 1.576% Cd. Overall, the Fe content in sphalerite was found to contribute to the visible light absorption ability and the recombination rate of photo-generated electrons and holes, while substitution by Cd was observed to have a greater effect on the photocatalytic properties. These findings provide a scientific basis for the profitable utilization of base metal resources like sphalerite.

Enterococcal isolates from bovine subclinical and clinical mastitis: Antimicrobial resistance and integron-gene cassette distribution.

Bovine mastitis is one of the most prevalent and costly diseases, and can be caused by a variety of bacterial pathogens including enterococci. Unfortunately, comprehensive studies about the prevalence and antimicrobial resistance profiles of entercocci are scarcely reported. This study aimed to investigate the occurrence of enterococci associated with bovine clinical mastitis and subclinical mastitis, to assess their antimicrobial resistance profiles, and to detect the distribution of integrons and gene cassette arrays in Liaoning of China. Our results indicated subclinical mastitis occurred in 34.3% of bovine, and 21.4% of bovine were positive for clinical mastitis, meanwhile Enterococcus faecium is the predominant pathogen in both clinical mastitis and subclinical mastitis. More than 50% of the total isolates were resistant to penicillin, ceftiofur, tylosin, lincomycin, and oxytetracycline. Class I integrons was detected in enterococcal isolates from both clinical and subclinical mastitis with 57.1% and 45.3%, respectively. Meanwhile, class II integrons only were observed in enterococcal isolates from subclinical mastitis. Multidrug resistance has become prevalent in enterococci isolated from clinical mastitis and subclinical mastitis in Liaoning, northeast of China. This study revealed that enterococcal isolates had shown resistant to ß-lactam antibiotics including penicillin, and different therapeutic programs should be carried out in Liaoning of China.

Correction to: Pluronic­based nano­self­assemblies of bacitracin A with a new mechanism of action for an efficient in vivo therapeutic effect against bacterial peritonitis.

In the original publication of the article [1], the Fig. 8c and d was published with incorrect values. The corrected Fig. 8c and d is given below.

Pluronic-based nano-self-assemblies of bacitracin A with a new mechanism of action for an efficient in vivo therapeutic effect against bacterial peritonitis.

BACKGROUND: Although assemblies of hydrophobic-modified bacitracin A with PLGA (Nano-BAPLGA) have demonstrated promising antibacterial activities against both Gram-positive and Gram-negative bacteria, the desirable antibacterial potency has remained challenging due to the low solubility of Nano-BAPLGA. To address this tissue, a series of Pluronic copolymers (Pluronic® F127, Pluronic® P123 and Pluronic® P85) were selected to link the N-terminus of bacitracin A to construct Pluronic-based nano-self assemblies (Nano-BAF127, Nano-BAP123 and Nano-BAP85). RESULTS: Impressively, all the newly designed Pluronic-based Nano-BAs possessed higher solubility and stronger effectiveness against both Gram-positive and Gram-negative bacteria compared with Nano-BAPLGA, especially the modification with Pluronic® P85. Surface tension measurements indicated that Nano-BAP85 was much more tensioactive than Nano-BAPLGA, which usually translated into a good membranolytic effect. Fluorescence spectroscopy and electron microscopy analyses confirmed the speculation that the cell wall/membrane might be the main action target of Nano-BAP85 by permeabilizing the cell membrane and damaging the membrane integrity. In vivo results further demonstrated that Nano-BAP85 significantly suppressed bacterial growth and prolonged survival time in the bacterial peritonitis mouse model with negligible toxicity. CONCLUSIONS: Collectively, the membrane targeting mechanism of action is entirely distinct from those of clinically used antibacterial agents. Furthermore, the new approach of construction nanoantibiotics based on the modification of commercially available antibiotics with Pluronic copolymers is demonstrated to have an efficient therapeutic effect against bacterial infection.

The phylogenetic group, antimicrobial susceptibility, and virulence genes of Escherichia coli from clinical bovine mastitis.

Bovine mastitis is still a central problem on dairy farms despite control programs, and Escherichia coli is a crucial pathogen during the development of bovine mastitis. The virulence genes, antimicrobial susceptibility, and mortality of mice infected with different E. coli isolates from bovine mastitis were determined in this study. According to the presence of the specific genes chuA, yjaA, and TspE4.C2, these isolates mainly belonged to 2 different groups: group A (47/79) and group B1 (22/79). The ompC gene was detected in all the isolates, followed by fimH (89.9%), ECs3703 (88.6%), and ompF (73.4%), whereas most of the virulence genes were not detected in these isolates. The results of the antimicrobial susceptibility tests indicated that the isolates were susceptible to the fluoroquinolones and aminoglycosides. An inverse relationship was shown between the expression level of ompF and antimicrobial resistance; additionally, the isolates that were nonsusceptible to at least 4 classes of antimicrobial agents showed a lower mortality to mice in comparison with the susceptible isolates. This study indicated that antibiotic resistance had emerged in E. coli from bovine mastitis in this area, and appropriate measures should be taken to avoid potential threats to humans and other animals.

Trueperella pyogenes isolated from dairy cows with endometritis in Inner Mongolia, China: Tetracycline susceptibility and tetracycline-resistance gene distribution.

Trueperella pyogenes plays a crucial role in endometritis pathogenesis and is also associated with many infections, including metritis, mastitis, arthritis and liver abscessation, in many domestic animals. In this study, we investigated the prevalence of tetracycline resistance in T. pyogenes isolated from dairy cows with endometritis in Inner Mongolia, China, and we assessed tetracycline-resistance gene distribution among the isolates. Our results indicated that 68.7% and 62.5% of the isolates were resistant to tetracycline and doxycycline, respectively, and the rate of resistance to metacycline was 18.8%. The tetracycline resistance gene tetK was present in all isolates (n = 32), whereas the tetM gene was identified in 12.5% and 9.4% of the isolates, in the chromosome and plasmid, respectively. Strains carrying tetW were also common in the chromosome and plasmid, with abundances of 53.1% and 46.9%, respectively. However, tetO and otrA were absent in all isolates. The resistance phenotype analysis indicated that 6.3% of strains were susceptible to all tetracyclines, while 3.1% showed resistance to all tetracyclines.

RESEARCH ON EXTRACTION TECHNOLOGY, ANTIBACTERIAL AND ANTIOXIDANT ACTIVITY OF ETHANOL EXTRACT FROM LEAVES OF ABUTILON THEOPHRASTI MEDIC.

This paper described the extraction procedure and determination method for the total flavonoids in ethanol extract from the leaves of Abutilon theophrasti Medic., and evaluated antibacterial and antioxidant activity. Maximum extraction yield was achieved using 60% ethanol, 1 : 30 (g/mL) of a ratio of material to solvent, 20 min of extraction time, 40 kHz of ultrasonic frequency, 100 W of ultrasonic power, 600C of extraction temperature and two extraction cycles. Total flavonoids content was 16.79 RE mg/g medicinal materials. The extracts had effective antibacterial activity against 24 test strains from S. aureus and E. coli, MICs ranged from 2.18 to 8.7 mg/mL; it was also revealed that the extracts demonstrated high flavonids content and potent antioxidant activity, achieved by hydroxyl radical, DPPH radical and ABTS radical scavenging. These results indicated thathe extract may be a promising plant demonstrating antibacterial and antioxidant activities.

Antibacterial and antioxidant properties of various solvents extracts of Abutilon theophrasti Medic. leaves.

This paper described the extraction procedure of six extracts from Abutilon theophrasti Medic. leaves and evaluated antioxidant and antibacterial activity of different extracts by hydroxyl radical, DPPH radical scavenging, broth micro-dilution and agar-well diffusion methods. The six extracts were prepared by the two extraction procedures: (I) water was the extraction solvent; (II) 90% alcohol extract was extracted by petroleum ether, chloroform, ethyl acetate and n-butanol in turn. Extract yields were 7.34%, 7.31%, 0.45%, 0.12%, 2.70% and 5.68% for extract I to VI. It was revealed that the various extracts had effective antibacterial activity against four test strains from Staphylococcus aureus (ATCC 25923), Streptococcus (ATCC 49619), Escherichia coli (ATCC 25922) and Salmonella (ATCC 01303); meanwhile, the six extracts demonstrated potent antioxidant activity, achieved by hydroxyl radical and DPPH radical scavenging assay. Minimum inhibitory concentrations (MICs) for the bacterial species ranged from 2.21 to 539.46 mg/ml, diameter of inhibition zone ranged from 2.08 to 15.05mm. The scavenging •OH and DPPH• rates were 62.37% to 81.86% with the concentration 0.06 to 1.89mg/ml and 37.80% to 81.23% with the concentration 1.07 to 35.52mg/ml. According to the results, these extracts have antioxidant and antibacterial activity. In view of all the facts collectively, the six extracts will become natural and nontoxic antioxidant and antibacterial agent, and be applied in food and pharmaceutical industries for the prevention or treatment caused by microorganisms and free radicals.

Resistance to ß-lactam antibiotic may influence nanH gene expression in Trueperella pyogenes isolated from bovine endometritis.

Virulence could be modulated by many instinctive and environmental factors including oxygen, osmolarity and antimicrobial agents. This study aimed to investigate the correlation between drug resistance and the nanH expression in Trueperella pyogenes (T. pyogenes). Minimum inhibitory concentrations (MICs) of 6 ß-lactam antimicrobial agents (penicillin G, amoxicillin, oxacillin, cefazolin, ceftiofur, and ampicillin) against T. pyogenes were tested by standard broth dilution method according to the protocols of the Clinical and Laboratory Standards Institute (CLSI), and real-time fluorescent quantitative reverse transcription-polymerase chain reaction (RT-PCR) was selected to investigate the mRNA expression levels of the nanH in T. pyogenes. All the isolates were resistant to atleast 2 of antimicrobial agents, and multidrug resistance (resistance to atleast 3 antimicrobials) was observed in 84.38% (27/32) of isolates. The mRNA expression levels of the nanH were significantly higher in comparison with that in ATCC19411, as the resistance profile enlarged, the nanH mRNA expression levels decreased in T. pyogenes. These results indicated that ß-lactam antibiotic resistance in T. pyogenes may alter the expression of the nanH.

Protective effects of apocynin on atrial electrical remodeling and oxidative stress in a rabbit rapid atrial pacing model.

It has been proposed that apocynin might be used in the prevention and management of atrial fibrillation (AF). The purpose of this study was to investigate the effects of apocynin on atrial electrical remodeling and oxidative stress promoted by rapid atrial pacing (RAP) in rabbits. New Zealand white rabbits were subjected to RAP with or without apocynin treatment. Serial electrophysiological studies (EPS) were performed at baseline and every half hour after RAP onset. Superoxide dismutase (SOD) and lactate dehydrogenase (LDH) activities and Ca²âº content in tissue homogenates of both atria were assayed after EPS. In the RAP group but not in the sham-operated and RAP with apocynin groups, atrial effective refractory periods (AERPs) at cycle length of 200 and 150 ms shortened most clearly by 20.8 ± 10.2 ms at 3 h (P < 0.001) and by 12.8 ± 11.1 ms at 2 h (P < 0.05) respectively, and AERP rate adaptation decreased to minus values. Higher AF inducibility (66.7%) and longer AF duration (an average of 37.8 min) were presented in the RAP group. Compared with the other groups, SOD activity was lower, and LDH activity and Ca²âº content were higher in the RAP group. Similar differences were not found between the sham-operated and the RAP with apocynin treatment groups. These data show that apocynin attenuates the development of atrial electrical remodeling in a short period of 3-hour RAP, and reduces RAP-mediated inducibility and duration of AF in this model.

CT-based radiomics combined with hematologic parameters for survival prediction in locally advanced esophageal cancer patients receiving definitive chemoradiotherapy.

OBJECTIVES: The purpose of this study was to investigate the prognostic significance of radiomics in conjunction with hematological parameters in relation to the overall survival (OS) of individuals diagnosed with esophageal squamous cell carcinoma (ESCC) following definitive chemoradiotherapy (dCRT). METHODS: In this retrospective analysis, a total of 122 patients with locally advanced ESCC were included. These patients were randomly assigned to either the training cohort (n = 85) or the validation cohort (n = 37). In the training group, the least absolute shrinkage and selection operator (LASSO) regression was utilized to choose the best radiomic features for calculating the Rad-score. To develop a nomogram model, both univariate and multivariate analyses were conducted to identify the clinical factors and hematologic parameters that could predict the OS. The performance of the predictive model was evaluated using the C-index, while the accuracy was assessed through the calibration curve. RESULTS: The Rad-score was calculated by selecting 10 radiomic features through LASSO regression. OS was predicted independently by neutrophil-to-monocyte ratio (NMR) and Rad-score according to the results of multivariate analysis. Patients who had a Rad-score > 0.47 and an NMR > 9.76 were at a significant risk of mortality. A nomogram was constructed using the findings from the multivariate analysis. In the training cohort, the nomogram had a C-index of 0.619, while in the validation cohort, it was 0.573. The model's accuracy was demonstrated by the calibration curve, which was excellent. CONCLUSION: A prognostic model utilizing radiomics and hematologic parameters was developed, enabling the prediction of OS in patients with ESCC following dCRT. CRITICAL RELEVANCE STATEMENT: Patients with esophageal cancer who underwent definitive chemoradiotherapy may benefit from including CT radiomics in the nomogram model. KEY POINTS: • Predicting the prognosis of ESCC patients before treatment is particularly important. • Patients with a Rad-score > 0.47 and neutrophil-to-monocyte ratio > 9.76 had a high risk of mortality. • CT-based radiomics nomogram model could be used to predict the survival of patients.

Effect of colistin exposure on calcium homeostasis and mitochondria functions in chick cortex neurons.

The study investigated the effect of colistin exposure on calcium homeostasis and mitochondria functions in neurons. We used an in vitro drug model to induce neurotoxicity that closely mimic the in vivo condition by exposing primary cultures of chick cortex neurons to different concentrations of 0, 0.83, 4.15 and 8.3 µg/mL colistin. The cell activity was determined by methods of MTT and lactate dehydrogenase release at 24 h post-beginning. The membrane potential (ΔΨm) and ultrastructure of mitochondrial were assessed. The calcium ion concentration within neurons ([Ca(2+)]i) was detected using the Fura3/AM as the probe and expression level of intracellular calmodulin (CaM) mRNA was detected by reverse transcription polymerase chain reaction. The results showed that, in the 4.15 and 8.3 µg/mL colistin groups, the functions of mitochondria altered, the ΔΨm was significantly decreased and the mitochondrial cristae was swollen and even vacuolar degeneration in mitochondria occurred. Moreover, the expression level of colistin could decrease CaM mRNA, and increase free calcium concentration. The present work revealed that colistin-induced mitochondria dysfunction and calcium homeostasis disequilibrium, providing new insight into the toxicological mechanism of colistin in neurons.

Application of improved transformer based on weakly supervised in crowd localization and crowd counting.

To the problem of the complex pre-processing and post-processing to obtain head-position existing in the current crowd localization method using pseudo boundary box and pre-designed positioning map, this work proposes an end-to-end crowd localization framework named WSITrans, which reformulates the weakly-supervised crowd localization problem based on Transformer and implements crowd counting. Specifically, we first perform global maximum pooling (GMP) after each stage of pure Transformer, which can extract and retain more detail of heads. In addition, we design a binarization module that binarizes the output features of the decoder and fuses the confidence score to obtain more accurate confidence score. Finally, extensive experiments demonstrate that the proposed method achieves significant improvement on three challenging benchmarks. It is worth mentioning that the WSITrans improves F1-measure by 4.0%.

Molecular characteristics of Staphylococcus aureus strains isolated from subclinical mastitis of water buffaloes in Guangdong Province, China.

Intramammary infections (IMI) in animals reared for milk production can result in large economic losses and distress to the animals. Staphylococcus aureus is an important causative agent of IMI in dairy cows, but its prevalence in water buffaloes has not been determined. Therefore, the current study was conducted to investigate the prevalence of subclinical mastitis in water buffaloes and the antimicrobial susceptibility, virulence genes and biofilm formation abilities of Staphylococcus aureus isolates recovered from water buffaloes in Guangdong, China. Staphylococcus aureus strains were isolated from milk samples of water buffaloes with subclinical mastitis, and twofold microdilution, PCR and crystal violet staining methods were used to determine antimicrobial susceptibility, distributions of virulence and antimicrobial resistance genes and biofilm formation ability, respectively. Our results indicated that 29.44% of water buffaloes were diagnosed with subclinical mastitis, and the most prevalent pathogens were Escherichia coli (96.17%), coagulase-negative staphylococci (CoNS) (67.60%) and S. aureus (28.57%). Most S. aureus isolates showed resistance to bacitracin, doxycycline, penicillin, florfenicol, and tetracycline but were susceptible to ciprofloxacin, ceftizoxime, cefoquinoxime, and ofloxacin. Moreover, 63.72% of S. aureus isolates were positive for tetM, and the prevalence of msrB, blaZ, mecA, fexA, and tetK ranged from 21.24 to 6.19%. All S. aureus isolates harbored clfB and icaA genes, and the virulence genes hla (93.8%), hld (91.15%), clfA (90.27%), fnbA (86.73%), and hlb (83.19%), and tsst, icaD, sec, see, fnbB, and sea showed a varied prevalence ranging from 3.5 to 65.49%. All S. aureus isolates possessed the ability to form biofilms, and 30.09% of isolates showed strong biofilm formation abilities, while 19.47% of isolates were weak biofilm producers. Our results indicated that subclinical mastitis is prevalent in water buffaloes in Guangdong, China, and S. aureus is prevalent in samples from water buffaloes with subclinical mastitis. Most S. aureus isolates were susceptible to cephalosporins and fluoroquinolones; thus, ceftizoxime and cefoquinoxime can be used to treat subclinical mastitis in water buffaloes.

The pharmacokinetics of tilmicosin in plasma and joint dialysate in an experimentally Mycoplasma synoviae infection model.

Mycoplasma synoviae (MS) infection is a serious threat to poultry industry in China, thus it is essential to study the pharmacokinetics (PK) in the target site of MS-infected chickens, but there are no relevant reports at present. The aim of this study was to compare the PK of tilmicosin in plasma and joint dialysate in MS-infected chickens. The MS infection model was established by evaluating the influence factors of the susceptibility of chicken species, day age of chicken, infection routes, infection cycle, infection dose, and stress response. The clinical symptoms, pathogen isolation, PCR identification, and ELISA antibody were detected to determine whether the MS infection model has been successfully established. Eight-week-old Mahuang chickens were challenged with MS by joint combined with footpad, 2 mL each time, twice a day for 5 d, then the MS infection model was successfully established. The infection group was orally administrated a single dose of 15 mg/kgbody weight (b. w.) tilmicosin. The joint dialysate was collected by the microdialysis technique, then the concentration of tilmicosin in plasma samples and joint dialysate were determined by triple quadrupole high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). There was no significant difference in elimination half-life (t1/2) and the mean residence time (MRT) of dialysate and plasma. In contrast, the time of the area under the concentration-time curve (AUC) and the (maximum concentration of tilmicosin in plasma) Cmax of tilmicosin in plasma was 2.1 and 1.4 times higher than in dialysate. The distribution coefficient of tilmicosin in joint and plasma (AUCdialysate/AUCplasma) was 0.51. In conclusion, tilmicosin concentration in joints of MS-infected chicken was much lower than that of plasma, which may result in the poor clinical effect and drug resistance. The study could provide a reference for the clinical use of tilmicosin against MS.