| Part One: Clinical characteristics of community-associated methicillin-resistant staphylococcus aureus(CA-MRSA)Objective: To analyze the clinical data of community-associated methicillin-resistant Staphylococcus aureus(CA-MRSA)pneumonia patients,summarize the clinical characteristics,and improve the understanding and diagnosis and treatment of the disease.Methods: Starting from a patient with CA-MRSA pneumonia cured by moxifloxacin,a retrospective study was used to collect information of 6 CA-MRSA patients,including clinical features,laboratory tests,imaging and therapeutic medications,from January2010 to June 2019 in Fuzhou General Hospital of Fujian Medical University.Results:Among the 6 patients,4 were male and 2 were female,aged 6～60 years.Most of them have fever(5/6,83%),body temperature is 38.5℃～40.5℃,some have cough(3/6,50%),and white sputum(3/6,50%).Most white blood cell counts are normal(4/6,67%),C-reactive protein is elevated,44.3-178 mg/L at the initial diagnosis,and some procalcitonin is elevated(3/6,50%),0.8-3.39 ng/ml at the initial diagnosis,partial erythrocyte sedimentation rate increased(3/5,60%),45-134 mm/h at the first diagnosis.Four of the 6 patients had chest CT data,all of which showed multiple lobular lesions(4/4,100%),morphological manifestations were nodular shadows with halo signs(2/4,50%),and patch consolidation(2/4,50%),in which 1 case showed multiple empty holes on the basis of nodular shadows during the review.All 6 patients were resistant to β-lactam antibiotics(6/6,100%),ciprofloxacin,levofloxacin,moxifloxacin and nitrofurantoin,rifampicin,linezolid,co-trimoxazole,vancomycin Are all sensitive(6/6,100%),most sensitive to gentamicin and tetracycline(5/6,83%),and most resistant to clindamycin and erythromycin(4/6,67%)).Before diagnosis,most empirical use of β-lactam antibiotics was used to fight infection(5/6,83%).Conclusion: Cavity and consolidation are the main CT features of CA-MRSA pneumonia.Moxifloxacin has certain antibacterial activity against CA-MRSA and can be used to treat CA-MRSA pneumonia.Part Two: Genome sequencing and comparative genomics research with CA-MRSA WXPM60Objective: A community-associated methicillin-resistant Staphylococcus aureus(CAMRSA)strain(WXPM60),which was isolated from bronchoalveolar lavage fluid(BALF)and caused community-acquired pneumonia,was analyzed for genomic sequence information,and the gene mutation of the strain was analyzed to provide a basis for the drug resistance mechanism and diagnosis and treatment of MRSA.Methods: The third-generation sequencing technology was used to perform wholegenome sequencing on WXPM60,and the software was used to perform sequence splicing,gene prediction,functional annotation,orthologous cluster annotation(COG),analysis of virulence factors and drug resistance genes.The evolutionary relationship analysis and comparison of virulence factors and drug resistance genes were conducted with domestic popular sequence type(ST type)strains.Results:The chromosome genome size of WXPM60 is 2,838,709 bp,and its genome complete sequence has been submitted to the NCBI Gen Bank database with accession number SAMN11402343.Evolutionary analysis showed that WXPM60 clustered with SA40,SA268,M013,SA957,HZW450,and ST243,which are also CA-MRSA.WXPM60 was classified as ST59.The comparative genome found that the virulence genes ebh,sak,esaB,esaA,essC,hrcN are unique to WXPM60,while the virulence genes ess C,esaB,esaA,seb,selk,selq are not included in WXPM60;WXPM60 contains resistance genes mepA,murA,arlR,mgrA,mepR,tet(38)and mecA,just like other ST59 strains.However,WXPM60 contains blaZ gene and does not contain opmE gene.Among them,mepA,murA,arlS,arlR,mepR,tet(38)and nora are all genes that are resistant to non-β-lactam drugs,but clinical susceptibility testing still suggests sensitivity.Conclusion: This study reported the whole genome sequence of CA-MRSA strain WXPM60.It was found that the virulence and drug resistance of this strain were similar to other ST59 strains,but the multiple drug resistance genes contained were not expressed. |
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