Molecular epidemiological analysis of Stenotrophomonas maltophilia strains in a teaching hospital in Shanghai / 中国感染与化疗杂志

ABSTRACT

Objective We evaluated the molecular epidemiology ofStenotrophomonas maltophilia strains in adult patients in Renji Hospital to Shanghai Jiao Tong University School of Medicine for better control ofS.maltophilia infections.Methods Nonduplicate clinical isolates of S.maltophilia were collected from Renji Hospital from January 2014 to September 2014.We examined the clonality among the S.maltophilia isolates by multilocus sequence typing (MLST) and pulsed field gel electrophoresis (PFGE).Antimicrobial resistance pattern was investigated by Kirby-Bauer method and prevalence of toxin genes (Stmpr1,Stmpr2,stmr-1,Smlt3773locus) by PCR.We also studied the biofilm formation of S.maltophilia by semiquantitative biofilm formation test.Results A total of 78 nonduplicate S.maltophilia isolates were analyzed,of which 26 were isolated from surgical intensive care unit,and 53 strains were from male patients.All patients infected by S.maltophilia had received antibiotic therapy before the strains were isolated.At least three kinds of antibiotics were used in 62.8％ of the patients.MLST analysis indicated that 49 isolates were assigned novel STs(STnewl-STnew38),with new combinations of allelic profiles.The largest cluster of isolates was ST23 (6 strains).PFGE showed that there was weak genetic linkage between S.maltophilia strains.The 78 isolates were divided into 58 groups.About 2.6％ (2/78) and 10.3％ (8/78) of these strains were resistant to levofloxacin and trimethoprim-sulfamethoxazole,respectively.All the strains were susceptible to minocycline.The prevalence of virulence genes Stmprl,Stmpr2,snf-1 and Smlt3773 locus was 79.5％ (62/78),93.6％ (73/78),94.9％ (74/78) and 48.7％ (38/78),respectively.Biofilm formation test indicated that the mean ability of biofilm formation was 0.51±0.44 in terms of D492.There was no significant difference between males and females.Conclusions All patients with Stenotrophomonas maltophilia infection had a history of antibiotic use and male patients were susceptible population.Stenotrophomonas maltophilia isolates showed high prevalence of virulence genes.No clonal dissemination was found in the same department of hospital.