Clonal Diversity, Biofilm Formation, and Antimicrobial Resistance among Stenotrophomonas maltophilia Strains from Cystic Fibrosis and Non-Cystic Fibrosis Patients

Abstract

The intrinsic antibiotic resistance of Stenotrophomonas maltophilia, along with its ability to form biofilm both on abiotic surfaces and host tissues, dramatically affects the efficacy of the antibiotic therapy. In this work, 85 S. maltophilia strains isolated in several hospital of central Italy and from several clinical settings were evaluated for their genetic relatedness (by pulsed-field gel electrophoresis, PFGE), biofilm formation (by microtiter plate assay), and planktonic antibiotic resistance (by Kirby–Bauer disk diffusion technique). The S. maltophilia population showed a high genetic heterogeneity: 64 different PFGE types were identified, equally distributed in cystic fibrosis (CF) and non-CF strains, and some consisted of multiple strains. Most of the strains (88.2%) were able to form biofilm, although non-CF strains were significantly more efficient than CF strains. CF strains produced lower biofilm amounts than non-CF strains, both those from respiratory tracts and blood. Non-CF PFGE types 3 and 27 consisted of strong-producers only. Cotrimoxazole and levofloxacin were the most effective antibiotics, being active respectively against 81.2% and 72.9% of strains. CF strains were significantly more resistant to piperacillin/tazobactam compared to non-CF strains (90% versus 53.3%), regardless of sample type. Among respiratory strains, cotrimoxazole was more active against non-CF than CF strains (susceptibility rates: 86.7% versus 75%). The multidrug resistant phenotype was significantly more prevalent in CF than non-CF strains (90% versus 66.7%). Overall, the multidrug-resistance level was negatively associated with efficiency in biofilm formation. Our results showed, for the first time, that in S. maltophilia both classical planktonic drug resistance and the ability of biofilm formation might favor its dissemination in the hospital setting. Biofilm formation might in fact act as a survival mechanism for susceptible bacteria, suggesting that clinical isolates should be routinely assayed for biofilm formation in diagnostic laboratories.

Antibacterial and Antivirulence Activity of Glucocorticoid PYED-1 against Stenotrophomonas maltophilia

“…Interestingly, the same concentration of PYED-1 has a synergistic effect with gentamicin or amikacin on bacterial growth inhibition. This is in agreement with other studies showing that S. maltophilia biofilm formation plays a notable role in the development of antibiotic resistance [20][21][22].…”

“…Most S. maltophilia strains form biofilms on several biotic and abiotic surfaces, and this greatly contributes to the pathogenicity of these bacteria [20][21][22]. Thus, the antibiofilm properties of PYED-1 against S. maltophilia K279a were investigated.…”

“…However, the allergenic reaction, the intolerance, and the increasing rates of resistance limit the use of Trimethoprim-sulfamethoxazole [18,19]. S. maltophilia infections are also difficult to treat due to the ability of this bacterium to form highly structured and multilayered biofilms [20][21][22]. Because of the potential for resistance development, there is need of novel antimicrobials for S. maltophilia infection treatment.…”

Modulated Response of Aspergillus fumigatus and Stenotrophomonas maltophilia to Antimicrobial Agents in Polymicrobial Biofilm

“…Mowat et al ( 2007 ) showed that amphotericin B, itraconazole, voriconazole, and caspofungin were 1,000 times less efficient on biofilm-life form than on planktonic form. Several studies showed that levofloxacin could be an alternative to treat S. maltophilia infections (King et al, 2010 ; Wu et al, 2013 ; Herrera-Heredia et al, 2017 ; Pompilio et al, 2020 ). This molecule could reduce biofilm biomass (Di Bonaventura et al, 2004 ; Passerini de Rossi et al, 2009 ), but some levofloxacin-resistant strains emerge (Wang et al, 2020 ).…”

The Toxin-Antitoxin Systems of the Opportunistic Pathogen Stenotrophomonas maltophilia of Environmental and Clinical Origin

“…The mortality rate of S. maltophilia infection can exceed 35% [ 3 ], with the World Health Organization (WHO) listing S. maltophilia as one of the leading multidrug-resistant pathogens [ 4 ]. The most known S. maltophilia features contributing to its successful adaptation in clinical environments include intrinsic antibiotic resistance mechanisms and its ability to form biofilms [ 5 ], although other less characterized factors (synthesis of extracellular enzymes, bacterial motility, and quorum sensing) are also known to influence its pathogenesis [ 6 ]. S. maltophilia is also known as a highly diverse species, since numerous studies have revealed genotypic diversity between clinical S. maltophilia isolates [ 7 , 8 , 9 ], even when analyzing samples from the same hospital [ 10 , 11 ].…”