| Objective:To explore the related virulence factors of clinical isolates of Acinetobacter baumannii.Methods:By collecting clinical data of clinical isolates of A.baumannii in the First Affiliated Hospital of Nanchang University,the correlation between its clinical characteristics and prognosis was analyzed;the multi-site sequencing method was used to identify the ST type of strains;The strain virulence was analyzed by the survival rate of Galleria mellonella after infected and the serum bactericidal assay;the strain’s biofilm formation ability was evaluated by using crystal violet staining;Moreover,we explored the relationship between the strain virulence with ST typing,biofilm formation,and strain resistance.Relusts:1.The incidence of ICU admission,mechanical ventilation,indwelling gastrointestinal tract,respiratory failure and sepsis in the group with poor prognosis were higher than those in the group with good prognosis,and the difference was statistically significant(P=0.017,P=0.0005,P=0.0003,P=0.007,P=0.017).2.The platelet count in the group with good prognosis(281.35×10~9±150.44×10~9)was higher than that in the group with poor prognosis(219.87×10~9±148.28×10~9),with statistically significant difference(P=0.027).3.The separation sites of strains were blood,sputum,alveolar lavage fluid,cerebrospinal fluid,puncture fluid,pus,throat swab,catheter tip,urine,tissue,secretions,drainage fluid and other parts respectively.The difference between the good prognosis and poor prognosis group is statistically significant(P=0.03).4.A total of 12 ST types were identified in 118 clinically isolated A.baumannii.They were ST1417(16.67%),ST191(12.5%),ST208(12.5%),ST1145(8.33%),ST1144(8.33%),ST457(4.17%),ST1712(4.17%),ST1696(4.17%),ST136(4.17%),ST368(4.17%),ST540(4.17%)and new subtypes not included in MLST Database(16.67%),the most were ST1417 and new subtypes,followed by ST191 and ST208.5.The 96 hours mortality rate of Galleria mellonella after infected in ST457,ST191,ST208,ST1144 and ST1145 was higher than that of the highly virulent standard strain(AB5075),and the difference between the mortality rate of Galleria mellonella and the mortality rate of the highly virulent strain after infected with the five types of strains was statistically significant(P=0.0001).6.The survival rates of ST191,ST457,ST1145,ST1144 and ST208 in serum were 67.65%,133.89%,89.16%and 80.9%respectively,which were higher than those of the standard strain ATCC 19606.7.Among 31 strains of A.baumannii,the number of biofilm strong positive strains was 6(19.35%),the number of positive strains was 5(16.13%),the number of weak positive strains was 13(41.94%),and the number of negative strains was 7(22.58%).The 96 hours mortality rate of biofilm positive strains was higher than that of biofilm negative strains,but the difference was not statistically significant(P=0.6549).8.Among 31 clinically isolated A.baumannii,8 were multidrug-resistant strains(25.81%),19 were multidrug-resistant strains(61.29%),and 4 were sensitive strains(12.90%).The 96 hours mortality rate of drug-resistant bacteria was higher than that of sensitive bacteria,and the difference was statistically significant(P=0.0017).Conclusion:1.Clinical epidemiology found that patients with respiratory failure,sepsis,mechanical ventilation,indwelling gastrointestinal canal and ICU admission have a poor prognosis;platelet count and different specimen source also affected the prognosis of patients.In our work,the patient’s condition should be comprehensive and give to them timely and reasonable treatment.2.A highly virulent A.baumannii strain was found in our hospital,reminding clinicians that the ST type of the strain should be identified in time,and early treatment to reduce mortality.3.The virulence of A.baumannii is related to the drug resistance of the strain,it is crucial to apply antibiotics timely and reasonably. |
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