Multilocus Sequence Typing for Molecular Epidemiology of Stenotrophomonas maltophilia Clinical and Environmental Isolates from a Tertiary Hospital in West of Iran

Background: Stenotrophomonas maltophilia is an opportunistic bacterium, contributing to different hospital-acquired infections and can be acquired from different hospital setting sources. Epidemiological study of S. maltophilia in the hospital also demonstrates the intrahospital distribution of certain strains of bacteria in healthcare facilities. The aim of the current study was to identify the molecular epidemiology of S. maltophilia isolates from clinical and environmental sources within a hospital.

Methods: A total of 400 samples (clinical and environmental) were collected from the different settings of hospital. Following the standard biochemical testing and 23S rRNA genotyping, the molecular typing of S. maltophilia isolates was determined using the multilocus sequence typing (MLST) technique. Also, the frequencies of zot and entF virulence genes among S. maltophilia isolates were examined by PCR technique.

Results: Based on the biochemical testes and PCRs targeting 23S rRNA gene, 22 S. maltophilia isolates were identified. The MLST analysis demonstrated that these isolates were assigned to 14 ST, and 6 out of 14 STs were common among clinical and environmental samples. All 22 isolates were identified in the PubMLST database. The PCR screening demonstrated that none of 22 S. maltophilia isolates had zot virulence gene, while the entF gene with the 59% frequency was observed in 13 out of 22 isolates. Among these 13 isolates, 6 STs were common in clinical and environmental isolates.

Conclusion: Our study showed the clonal relatedness between clinical and environmental sources of the S. maltophilia isolates in a hospital. Further studies are required to understand the epidemic situation of this pathogen in the clinic and the environment.