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Biofilm Formation among Stenotrophomonas maltophilia Isolates Has Clinical Relevance: The ANSELM Prospective
Arianna Pompilio1,2, Marco Ranalli1,2, Alessandra Piccirilli3
1Laboratory of Clinical Microbiology, Department of Medical, Oral and Biotechnological Sciences, "G. d'Annunzio" University of Chieti-Pescara, 66100 Chieti, Italy.
Abstract:
The ability to form biofilms is a recognized trait of Stenotrophomonas maltophilia, but the extent of its clinical relevance is still unclear. The present multicenter prospective study (ANSELM) aims at investigating the association between biofilm formation and clinical outcomes of S. maltophilia infections. One hundred and nine isolates were collected from various geographical origins and stratified according to their clinical relevance. Biofilm formation was evaluated by the microtiter plate assay and correlated with microbiological and clinical data from the associated strains. Antibiotic susceptibility of the planktonic cells was tested by the disk diffusion technique, while antibiotic activity against mature biofilms was spectrophotometrically assessed. Most strains (91.7%) were able to form biofilm, although bloodborne strains produced biofilm amounts significantly higher than strains causing hospital- rather than community-acquired infections, and those recognized as "definite" pathogens. Biofilm formation efficiency was positively correlated with mechanical ventilation (p = 0.032), whereas a negative relationship was found with antibiotic resistance (r2 = 0.107; p < 0.001), specifically in the case of the pathogenic strains. Mature S. maltophilia biofilms were markedly more resistant (up to 128 times) to cotrimoxazole and levofloxacin compared with their planktonic counterparts, especially in the case of bloodborne strains. Our findings indicate that biofilm formation by S. maltophilia is obviously a contributing factor in the pathogenesis of infections, especially in deep ones, thus warranting additional studies with larger cohort of patients and isolates.
Insights
Stenotrophomonas maltophilia readily forms biofilms, particularly in severe infections. Biofilm presence increases resistance to antibiotics like cotrimoxazole and levofloxacin, highlighting its clinical significance.
Area of Science:
- Microbiology
- Clinical Medicine
- Infectious Diseases
Background:
- Stenotrophomonas maltophilia is known for biofilm formation, but its clinical impact remains uncertain.
- Understanding the link between biofilm production and infection outcomes is crucial for patient care.
Purpose of the Study:
- To investigate the association between biofilm formation by S. maltophilia and clinical outcomes.
- To evaluate the role of biofilm in S. maltophilia pathogenesis and antibiotic resistance.
Main Methods:
- A multicenter prospective study (ANSELM) analyzed 109 S. maltophilia isolates.
- Biofilm formation was assessed using microtiter plate assays.
- Antibiotic susceptibility of planktonic cells and mature biofilms was evaluated.
Main Results:
- Most S. maltophilia strains (91.7%) formed biofilms, with bloodborne strains showing higher production.
- Biofilm formation correlated positively with mechanical ventilation and negatively with antibiotic resistance.
- Mature biofilms exhibited significantly increased resistance (up to 128-fold) to cotrimoxazole and levofloxacin.
Conclusions:
- Biofilm formation by S. maltophilia is a significant factor in infection pathogenesis, especially deep-seated infections.
- Increased antibiotic resistance in biofilms warrants further investigation and potential therapeutic strategies.
- Larger cohort studies are needed to confirm these findings and guide clinical practice.
