Detection of virulence gene and molecular typing of Shigella boydii isolated from clinical sources / 天津医药

ABSTRACT

Objective To understand genetic distribution, drug resistance, molecular typing and the epidemiological relativeness between strains of the Shigella boydii virulence. Methods Nine Shigella boydii strains were isolated form stool samples of patients with diarrhea from the Enteric Disease Clinic of the Second Hospital of Tianjin Medical University in June-October 2015. The strains were identified by biochemical test and serum agglutination test. Antibiotics susceptibility test was carried out using the Kirby-Bauer method. Polymerase chain reaction was used for detecting virulence genes. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) technique were used to determine the epidemiological relationship between nine Shigella boydii strains. Results There were three subtypes in nine isolated Shigella boydii samples, including one, three and five isolates inⅠ,Ⅱ,Ⅳsubtypes respectively. All of the 9 isolates were multi-drug resistant. The resistant rate of these strains for ampicillin was 100%(9/9), and then the resistant rates of these strains for ceftazidime, streptomycin, gentamicin, trimethoprim/sulfamethoxazole, cefotaxime, ceftriaxone, norfloxacin and levofloxacin were 1/9, 4/9, 4/9, 4/9, 5/9, 5/9, 6/9, 6/9 and 6/9, respectively. All of these strains were sensitive to amikacin, cefperazone-sulbactam and imipenem. The ipaH was carried by all the testing strains, and none of the strains carried the sen, set1A, set1B, ial, virA, icsA and SigA. The detective rates of pic, sepA and sat were 4/9, 5/9 and 7/9 strains, respectively. Nine shigella boydii strains were divided into 8 PFGE types. The similarity between the spectrums of PFGE was 63.21%-100%. Multilocus sequence typing showed that six isolates were belonged to ST648, two isolates were ST131 and one isolate was ST10. Conclusion Nine isolates of Shigella boydii (divided into three subtyping) isolated from our hospital are multi-drug resistant and they have distant relationships, belonging to the dissemination of case.