| Objective To study the source and department distribution of Staphylococcus aureus(SA)strains isolated from clinical infected patients in our hospital,and to analyze the drug resistance of methicillin-resistant Staphylococcus aureus(MRSA)and methicillin-sensitive Staphylococcus aureus(MSSA)strain resistance;detection of virulence genes of strains isolated from different source samples,comparing differences in virulence gene distribution between MRSA and MSSA strains;studying the number of virulence genes carried by different source strains,and mastering their pathogenic characteristics and Risk factors provide assistance and guidance for clinical targeted treatment and control of the spread of the bacteria in the hospital.Methods Collecting 86 strains of non-repetitive S.aureus isolated from hospitalized and emergency department patients of Tianjin Medical University General Hospital from January 20 to January 2019,Identification of strains using traditional methods combined with mass spectrometry;The Viter-2compact automatic microbial analysis system and the supporting drug-sensitive card were used to test the susceptibility of the bacteria,the cephalosporin method was used in the initial screening experiment of MRSA,the results of drug resistance of commonly used antibacterial drugs were analyzed by WHONET5.6 software.References Synthetic primers,polymerase chain reaction(PCR)method for gene amplification of mecA gene and leukocidin gene(pvl),toxic shock syndrome toxin-I gene(tsst-I),enterotoxin gene(Detection of virulence genes such as sea and seb),hemolysin gene(hld),and fibronectin lectin genes(clfA and clfB),the amplified positive products were sequenced,Some positive products were screened for DNA sequencing,and the sequencing results were compared by Genbank online database.The positive detection rate of the virulence genes of Staphylococcus aureus from different sources was statistically analyzed using SPSS20.0 software.Results(1)This study collected 86 strains of Staphylococcus aureus,including 24strains(27.9 %)of MRSA and 62 strains(72.1 %)of MSSA,respectively;the specimens were divided into blood,wound secretion,sputum,and drainage,whichwere derived from blood specimens and There were more strains of wound secretion,and the composition ratio was 33.7% and 24.4%,respectively.The departments were mainly from ICU(including NICU,EICU),hematology,cardiovascular surgery,and nephrology,and their composition ratios were 29.1%,10.4%,9.3%,9.3%,respectively.(2)The drug sensitivity results showed that the sensitivity rate of86 strains of Staphylococcus aureus to vancomycin,tigecycline and linezolid was100.0%.The blood,secretion,sputum,and drainage specimen isolates are commonly used in clinically,10,10,9 and 8 resistant strains;blood specimen isolates to levofloxacin,ciprofloxacin and moxifloxacin The sensitivity of gentamicin and tetracycline was higher than 85.0%.The sensitivity of sputum isolates to penicillin,erythromycin and clindamycin was less than 35.0%,and that of cefoxitin-resistant strain was 24.For MRSA.(3)Results of gene amplification test: The mecA gene was detected in 23 of 24 strains of MRSA,and the mecA gene was not detected in 62 strains of MSSA.Among the 86 strains,the positive detection rate of the virulence gene clfA was 90.7%,and the positive detection rate of tsst-1 was 7.0%,all from MRSA.More than 90% of the strains carry at least 3 virulence genes;the proportion of strains carrying the four virulence genes in the MRSA strain is 50.0%.Conclusion The specimens of Staphylococcus aureus in clinical infection patients in our hospital are mainly blood and wound secretions.The distribution of the department is mainly ICU,hematology,and the source of specimens is consistent with the distribution of the departments;No vancomycin,tigecycline and linezolid resistant strains are found;Different types of strains have different resistance to antimicrobial agents;MSSA drug sensitivity is generally higher than MRSA;The mecA gene was not detected in MSSA,and almost all of MRSA carried the mecA gene;The positive rates of virulence genes pvl,sea,seb,hld,clfA,and clfB in MRSA and MSSA were statistically significant(P<0.05),and the virulence gene tsst-I was not detected in MSSA strain,sputum isolates carry more virulence genes and are more pathogenic. |
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