Molecular Epidemiological Characteristics And Biofilm-forming Ability Of Pediatric Acinetobacter Baumannii Isolates

Objective: To analyze the ST typing of clinical isolates of Acinetobacter baumannii in our hospital and understand their epidemiological characteristics;to explore the biofilm forming ability of different clinical isolates;to analyze the correlation between different film-producing strains and drug resistance and virulence;to provide a basis for clinical prevention,control and treatment of Acinetobacter baumannii infection and to improve the clearance efficiency and efficacy.Methods: Non-replicated A.baumannii strains isolated from various specimens in the clinical microbiology room of our pediatric department from March 2016 to December 2022 were collected and identified;strains were typed by multi-locus sequence analysis method(MLST);drug sensitivity assay was performed to detect drug resistance of A.baumannii isolates;96-well polystyrene plates were used to construct a biofilm model and crystalline violet staining was used to quantify biofilm formation ability and compare the resistance of A.baumannii antibacterial drugs with different biofilm formation ability;Cryptosporidium hidradi infection assay was performed to analyze the virulence of A.baumannii with different film-producing ability.Results: 1.MLST results: 48 strains belonged to 21 sequence types;ST130 was the dominant type in our pediatric department,7 strains belonged to this genotype,accounting for 14.5% of the total number of strains;other genotypes included ST606,ST2016,ST2642,etc.;2.The highest resistance rate of Ceftriaxone was 66% in our pediatric department;while the lowest resistance rates were 10% and 6% for tigecycline and cotrimoxazole;3.Among the 50 strains of A.baumannii selected for the study,43 strains(86%)were able to form biofilm,of which24 strains(48%)were strongly positive and had strong biofilm forming ability,10 strains(20%)were positive,9 strains(18%)With the increase of biofilm forming ability,the resistance rate of the tested strains to ceftriaxone showed an increasing trend,and the difference was statistically significant(P<0.05),and for cefepime,gentamicin,ciprofloxacin,levofloxacin,tobramycin and carbapenems,the resistance rate of strongly positive strains with biofilm forming ability was significantly higher than the other However,there was no statistical difference.There was no significant effect of biofilm forming ability on the resistance of tigecycline and amikacin.5.There were 14(14/24,58%),6(6/10,60%),5(5/9,56%)and 3(3/7,43%)strains of A.baumannii in each group,respectively,which caused the death of all nematodes after 96 h.The results of nematode mortality were not statistically different among the groups(P>0.05).Conclusion:1.Genomic typing of our pediatric patient Acinetobacter baumannii isolate MLST became polymorphic,in which ST130 was the dominant clonal strain;2.Low resistance rate of tigecycline and cotrimoxazole and highest resistance rate of ceftriaxone in children in our hospital;3.Positive correlation between biofilm formation ability and drug resistance of clinical isolates of Acinetobacter baumannii from our pediatric department;4.There was no correlation between the biofilm-forming ability of Acinetobacter baumannii and the virulence of the bacteria in our pediatric department.