The Antibiotic sensitivity of Stenotrophomonas maltophilia in a 5-year period and investigation of clonal outbreak with PFGE.

Introduction: Stenotrophomonas maltophilia, which is able to form a biofilm, has mostly been related to catheters when it is the agent in hospital infections; these infections generally present as bacteremia and pneumonia, which may progress with complications and result in death.

Methodology: The study included 153 S. maltophilia strains isolated from clinical samples sent to our hospital laboratory between 1 January 2014 and 30 June 2018. The bacteria were identified and their antibiotic sensitivity was determined using the VITEK-2 automated system. PFGE (Pulsed Field Gel Electrophoresis): The strains isolated from 34 patient clinical samples and from 1 patient bedcover were taken for PFGE examination.

Results: The TMP/SXT and levofloxacin sensitivity of 153 S. maltophilia strains was examined. TMP/SXT resistance was determined to be 39% and levofloxacin resistance at 5%. Among 35 S. maltophilia strains, seven genotypes were identified using the PFGE method. While three strains showed a specific genotype profile, the other 32 were determined to consist of four clusters. The cluster rate was therefore 91.4% (32/35).

Conclusions: There was a clonal relationship between the vast majority of the 35 S. maltophilia isolates, which suggests that there was a cross-contamination problem in the hospital. One strain (#4) was identified by dendrogram analysis showed a high rate of similarity to the other strains and was determined to be the common source of the cross-contamination.