Class 1 Integrons Increase Trimethoprim-Sulfamethoxazole MICs against Epidemiologically Unrelated Stenotrophomonas maltophilia Isolates

Abstract

Twenty-five plasmid-specified antimicrobial resistance determinants common to gram-negative bacilli from nosocomial infection were investigated from 31 Stenotrophomonas maltophilia isolates. Twenty-four clones were identified by pulsed-field gel electrophoresis, and in three clones that exhibited an increased trimethoprimsulfamethoxazole MIC, the sul1 determinant was found. These results support not only the higher spread of class 1 integrons compared to other mechanisms but also the potential limitation of using trimethoprimsulfamethoxazole for therapy of severe S. maltophilia infections.

Investigation of the Presence of Class 1, 2, 3 Integrons and Their Relationships with Antibiotic Resistance in Clinical Stenotrophomonas maltophilia Isolates

“…Bizim çalışmamızda tespit edilen qacL geni taşıyan iki suşun antimikrobiyal duyarlılık durumunun, içerdikleri gen bölgeleri ile ilişkisi ileri çalışmalarda değerlendirilebilir. Bir suşta saptanan aadA geni başka benzer çalışmalarda da tespit edilmiştir 13,19,20 . Bu gen bölgesi aminoglikozid grubu antibiyotiklere karşı direnci göstermektedir 26 .…”

Stenotrophomonas maltophilia: an Emerging Global Opportunistic Pathogen

“…The drug resistance mechanisms are acquired by the horizontal transfer of antibiotic resistance through plasmids, transposons, integrons, integron-like elements, insertion element common region (ISCR) elements, and biofilms (17,18,27,146,198,328). The molecular mechanisms of antibiotic resistance in S. maltophilia are described in more detail below (see "Antibiotic Resistance").…”

“…Several molecular mechanisms of S. maltophilia contribute to its multiantibiotic resistance, including plasmids, integrons, and transposons (27). A summary of these antibiotic resistance mechanisms is shown in Table 6.…”

“…The 3=-conserved end of the class 1 integron contains the sul1 gene, encoding resistance to sulfonamides, and the qacE⌬1 gene, encoding tolerance to antiseptics containing quaternary ammonium compounds (137,321). Class 1 integrons have been found in S. maltophilia isolates in North and South America, Australia, Asia, and Europe (27,55,198,328). Clonal expansion plays an important role in drug resistance dissemination.…”

“…Class 1 integrons have been reported to be responsible for increased TMP-SMX MIC values for S. maltophilia clinical isolates (27). The sul genes that contribute to resistance to TMP-SMX (328) have been reported to be associated with class 1 integrons (27) and insertion element common region (ISCR) elements.…”