Is S maltophilia Colistin Resistance on the Rise?

Investigators from the Universitat Autònoma de Barcelona have identified links between antibiotic resistant S maltophilia phenotypes and "quorum sensing."

Stenotrophomonas maltophilia acquisition can lead to difficult respiratory issues for the immunocompromised. The multidrug-resistant opportunistic infection has increased in incidence within health care and community settings alike.

Investigators from the Universitat Autònoma de Barcelona (UAB) have identified links between antibiotic resistant S maltophilia phenotypes and quorum sensing, a gene-regulation process which bacterium can use to coordinate adaptations to host-cell environment.

Results were published in Frontiers in Microbiology. On examining S maltophilia strains from various European countries, the UAB study team found a clonal group with unique virulence factors. The lineage possessed a higher degree of colistin-resistance and increased capacity to form biofilms.

“The main QS signaling molecule in S maltophilia is known as diffusible signal factor (DSF), and the rpf gene cluster is responsible for its synthesis and perception,” study authors wrote.

“Here, correlations between the rpf variant and antibiotic susceptibility, LPS electrophoretic profiles and virulence-related phenotypes were evaluated for a collection of 78 geographically and genetically diverse clinical strains of S maltophilia,” the authors continued.

Out of the clinical strains examined, 60.7% were multi-drug resistant. Despite this, most isolates were susceptible to trimethoprim-sulphamethoxazole and all to minocycline. More studies are needed to introduce monocycline into clinical practice, investigators noted.

Resistance to levofloxacin was detected in an increasing number of the strains evaluated in the new study, in addition to 6.5% of strains being trimethoprim-sulfamethoxazole resistant.

The results sound the alarm on the potential risk of resistant and virulent S maltophilia clones circulating in hospitals.

S maltophilia is becoming a significant opportunistic pathogen in health care settings globally, according to the UAB study team. Epidemiological and genetic studies within other settings could shed further light on the extent of the challenges ahead.

Related Coverage: A Decade of Details on Stenotrophomonas maltophilia

Frequently found in more wet environments, but also animals, food, and water sources, such infections can impact organs and tissue alike.

Sources of Stenotrophomonas maltophilia infections have included sink drains, hand-washing soap, contaminated disinfectants, nebulizers, and even hospital suction tubing. Additionally, showerheads and faucets tend to be a favorite hiding spot for the bug.

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