AUTHOR=Wang Lifeng , Wang Yu , Ye Kun , Qiu Xuemei , Zhao Qiang , Ye LiYan , Yang Jiyong 

TITLE=Molecular epidemiology, genetic diversity, antibiotic resistance and pathogenicity of Stenotrophomonas maltophilia complex from bacteremia patients in a tertiary hospital in China for nine years

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1424241

DOI=10.3389/fmicb.2024.1424241

ISSN=1664-302X

ABSTRACT=<sec id="sec1"><title>Background</title><p>The <italic>Stenotrophomonas maltophilia</italic> complex (Smc) has emerged as a significant nosocomial pathogen contributing to increased mortality rates, particularly in case of bloodstream infections.</p></sec><sec id="sec2"><title>Methods</title><p>This study employed whole-genome sequencing (WGS) to assess the genetic diversity, antimicrobial resistance profiles, molecular epidemiology and frequencies of virulence genes among 55 <italic>S. maltophilia</italic> isolates obtained from bacteremic cases over a 9-year period.</p></sec><sec id="sec3"><title>Results</title><p>Based on the threshold of 95% average nucleotide identity (ANI) and 70% digital DNA–DNA hybridization (dDDH) for genospecies delineation, we classified 37 isolates into 6 known species, all belonging to the Smc. The remaining 18 isolates sequenced in this study were assigned to 6 new genomospecies. Among the 55 isolates, we identified 44 different sequence types (STs), comprising 22 known and 22 novel allele combinations. The resistance rate of Smc against trimethoprim-sulfamethoxazole (TMP/SMX) was found to be 3.6%, with the <italic>sul1</italic> and class one integron integrase genes (<italic>intI</italic>) detected in these isolates. All Smc isolates were susceptible to minocycline. Furthermore, all Smc strains harbored the <italic>motA, pilU, smf-1 and Stmpr2</italic> genes. Genomospecies 1 (100%, <italic>n</italic> = 9), <italic>Stenotrophomonas maltophilia</italic> (84.21%, <italic>n</italic> = 19) and <italic>Stenotrophomonas sepilia</italic> (71.43%, <italic>n</italic> = 7) demonstrated a higher percentage of the <italic>afaD</italic> gene, which was also associated with a higher separation rate. In addition to <italic>motA</italic>, <italic>pilU</italic>, <italic>smf-1</italic>, <italic>and Stmpr2</italic> genes, all <italic>S. maltophilia</italic> strains (100%) contained <italic>entA</italic>, <italic>gspD</italic>, <italic>KatA</italic>, and <italic>stmPr1</italic> genes, while all genomospecies 1 strains (100%) contained <italic>afaD, entA</italic>, <italic>gspD</italic>, and <italic>KatA</italic> genes.</p></sec><sec id="sec4"><title>Conclusion</title><p>Our study highlights the genetic diversity among Smc isolates from patients with bacteremia, revealing 22 novel ST types, 58 new alleles and 6 new genomospecies. <italic>S. maltophilia</italic> and <italic>S. pavanii</italic> were found to carry more virulence factors, emphasizing the importance of accurate strain identification. Minocycline emerged as a promising alternative antibiotic for patients who were resistant to TMP/SMX.</p></sec>