Genotypic and Phenotypic Characterization of Stenotrophomonas maltophilia Isolated from Maharaj Nakorn Chiang Mai Hospital

Abstract

Stenotrophomonas maltophilia is an important opportunistic pathogen that is one of the major cause of nosocomial infection. It is a multidrug resistant bacterium that can colonize in a hospital setting and become a problem of the hospital control. Little is known about characteristics of this bacterium, especially in Thailand. This study was aimed to determine the genotypic and phenotypic characteristics of S. maltophilia isolates from Maharaj Nakorn Chiang Mai Hospital. Total of 200 S. maltophilia isolates were collected from 4 types of specimens of which most isolates were from sputum specimen. The investigation of clinical features of S. maltophilia infection found that most of patients who were infected with S. maltophilia, were male and aged people. Many patients were suffered with underlying illnesses and severe condition. In addition, S. maltophilia is usually found co-infected with other microorganisms. Genetic relationship and MLST analysis showed that a high degree of genetic diversity was observed among S. maltophilia isolates. A total of 141 sequence types (STs) were observed among 200 isolates. Of these 141 STs, 130 allelic profiles were identified as new sequence types. Construction of minimum spanning tree of global S. maltophilia revealed seven large clonal complexes which S. maltophilia from Thailand were dominated in most of clonal complexes and found to be a founder of some branches. S. maltophilia of Thailand were closely related to S. maltophilia from China, South Korea and the USA. The clonal complex analysis of Thai isolates identified major six different clonal complexes. Each group exhibited different antibiotic resistant properties and different phenotypes.