Antibacterial activity of bacillomycin D-like compounds isolated from Bacillus amyloliquefaciens HAB-2 against Burkholderia pseudomallei

Objective:To investigate the inhibitory effect on Burkholderia pseudomallei(B.pseudomallei)strain HNBP001 of a bacillomycin D-like cyclic lipopeptide compound named bacillomycin DC isolated from Bacillus amyloliquefaciens HAB-2.Methods:The antibacterial effect of bacillomycin DC on B.pseudomallei was determined using the disk diffusion method.The minimum inhibitory concentrations were evaluated by microdilution assay.In addition,transmission electron microscopy was performed and quantitative real-time polymerase chain reaction assay was carried out to determine the expression of Mex B,Opr D2,and qnr S genes.Results:Bacillomycin DC produced an inhibition zone against B.pseudomallei with minimum inhibitory concentration values of 12.5μg/mL 24 h after treatment and 50μg/mL at 48 and 72 h.Transmission electron microscopy showed that bacillomycin DC resulted in roughening cell surface and cell membrane damage.Quantitative real-time polymerase chain reaction analysis showed low expression of Mex B,Opr D2 and qnr S genes.Conclusions:Bacillomycin DC inhibits the growth of B.pseudomallei and can be a new candidate for antimicrobial agents of B.pseudomallei.

Burkholderia pseudomallei infection manifests as mediastinal/hilar lymphadenopathy: A case report

Rationale:This case report presents the diagnosis and etiology of hilar/mediastinal lymphadenopathy in a male patient.Patient concerns:A 49-year-old man presented with fever and dyspnea after physical exertion.Diagnosis:The patient was diagnosed with melioidosis by cultivation of lymph node aspirate on blood agar using the VITEK 2 compact system.Interventions:The patient was treated with ceftazidime intravenously,combined with trimethoprim/sulfamethoxazole orally for 1 week.Once the patient was discharged,he began a 12-week course of trimethoprim/sulfamethoxazole.Outcomes:The patient recovered after treatment with ceftazidime and trimethoprim/sulfamethoxazole.Conclusions:Melioidosis is an infectious disease that mainly occurs in tropical regions.It can cause severe sepsis and pneumonia,and the infection in some patients may become chronic.Endobronchial ultrasound-transbronchial needle aspiration is a useful technique in the diagnosis of patients with hilar/mediastinal lymphadenopathy.

Epidemiological characteristics of 369 tuberculosis patients with multidrug resistance inHainan Island: A cross-sectional study

Objective:To investigate the epidemic characteristics of multidrug resistant tuberculosis in Hainan,China,to provide basic information and theories for the prevention and control of multidrug resistant tuberculosis.Methods:A retrospective descriptive epidemiological study was conducted.Data of multidrug resistant tuberculosis in Hainan Island from January 1,2014 to December 31,2019 were collected for statistical analysis.The counting data were described by frequency(percentage),and the measurement data were described by mean±standard deviation.Chi square test was used to compare the differences between different groups.If P<0.05,the difference was statistically significant.Results:From 2014 to 2019,the multidrug resistant rate of tuberculosis in Hainan Island was 24.9%(369/1484),8.0%(63/791)in newly-treated tuberculosis,and 44.2%(306/693)in retreatedmultidrug resistant rate of tuberculosis in Hainan Island was 24.9%(369/1484),8.0%(63/791)in newly-treatedtuberculosis,and 44.2%(306/693)in retreated tuberculosis.The multidrug resistant rate of newly-treated tuberculosis decreased by 0.05%per year,while that of retreated tuberculosis increased by 0.03%per year.multidrug resistant tuberculosis was mainly distributed in the city of Haikou(83 cases),Danzhou(44 cases),Wenchang(42 cases),Wanning(37 cases)and Dongfang(32 cases),accounting for 64.5%of all multidrug resistant tuberculosis.Among 369 multidrug resistant tuberculosis,81.0%were male.The proportion of newly-treated cases was 17.1%(63/369),while the proportion of retreated cases was 82.9%(306/369),which was significantly higher than that of newly-treated cases.The multidrug resistant rate of tuberculosis in different years was different.Conclusion:The drug resistance rate of tuberculosis in Hainan Island is higher than the national average level,which needs attention.The epidemiological characteristics of multidrug resistant tuberculosis with different treatment history were different.

Research progress on the diversity and application of mosquito intestinal flora

Mosquitoes are an important medical insect and play a very important role in the process of biologically vector infectious diseases.A large number of bacterial communities are colonized in their intestines.In the process of interaction and symbiosis with mosquitoes,the bacterial community is in many ways.The life activities of mosquitoes have a significant impact.This article reviews the population structure of the mosquito intestinal flora,influencing factors,and the regulation of mosquito vector efficacy by the flora.

Construction of Burkholderia pseudomalleiΔrelA mutant and comparison of their biological characteristics

Objective: The relA gene,a gene associated with the synthesis of rigorous response signaling molecule (p)ppGpp in Burkholderia pseudomallei, was knocked out and its effects on the biological functions of bacterial growth, motility and biofilm formation were investigated. Methods: The plasmids with trimethoprim resistance (TPR) were modified by enzyme digestion and enzyme ligation method. The TPR fragment was linked to the suicide plasmid pK18mobSacB containing SacB sucrose killing gene by Bgl Ⅱ enzyme digestion site, and trimethoprim resistance was obtained Plasmid(TPR-pK18mobSacB);The relA gene of Burkholderia pseudomallei HNBP001 was knocked out by homologous recombinant gene knockout method, and the relA mutant was obtained. The growth, motility and biofilm phenotypes of Burkholderia pseudomallei HNBP001 were compared before and after the deletion of relA gene. Results: The relA mutant was successfully constructed. The growth rate, motility and biofilm formation of ΔrelA decreased. Conclusion: The modified plasmid TPR- pK18mobSacB can improve the knockout efficiency of HNBP001 strain, which can be widely used in the gene knockout of Burkholderia pseudomallei, and provide convenience for the laboratory to study the gene function of Burkholderia pseudomallei at the molecular level;The mutant of the relA gene inhibits the growth, motility and biofilm formation of HNBP001.

Basic researches on the new coronavirus and its clinical progress

The initial case of atypical pneumonia occurred in Wuhan,Hubei Province at the end of 2019 caused by a novel coronavirus,soon it broke out all over the country beyond our imagination.For the very beginning of the break-out,we were lack of acknowledge of the newly disease,but with the further researches go,we intend to know the virus and disease better in every aspect.In this review we focus on the recent paper have been published online about epidemiology,clinical characteristics and therapy,which might help doctors to have a better understanding of the very disease.