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Stenotrophomonas maltophilia is a common opportunistic microorganism and an important respiratory pathogen in cystic fibrosis (CF). The aim of this study was to determine antimicrobial resistance phenotypes, sequence-types (ST) and genetic determinants of antibiotic resistance in S. maltophilia strains recovered from CF patients in Russia. S. maltophilia isolates recovered from 170 CF patients were analyzed. Minimum inhibitory concentrations of antibacterial agents were determined using Sensititre Gram Negative GNX2F plates and the results were interpreted according to Clinical and Laboratory Standards Institute (CLSI) criteria. Whole-genome sequencing (WGS) was performed on MGISEQ-2000 platform. SPAdes software, Galaxy, ResFinder, Integrall and PubMLST were used for analysis of WGS data. S. maltophilia strains were identified from 24/170 (14%) CF patients. In total, 25 isolates were detected, two strains were isolated from the same patient. The isolates belonged to 17 different STs, including 5 new STs; ST4 was the most prevalent ST. Resistance to ceftazidime was observed in 60% of strains, to ticarcillin-clavulanate - in 32%, to levofloxacin - in 24%, to trimethoprim/sulfamethoxazole - in 12% of strains. All isolates were susceptible to minocycline. All ST4 isolates were resistant or intermediate to ceftazidime and ticarcillin-clavulanate. In two isolates, the sul1 gene was detected. In one isolate, sul1 was part of a class 1 integron. The detected integron also contained the blaGES-7 and aac(6’)-Ib-cr genes. The ST4 sequence-type was the most prevalent ST among S. maltophilia strains recovered from CF patients in Russia. Antibiotic resistance genes, including sul1, blaGES-7, aac(6’)-Ib-cr, were detected in single strains.

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Background: Anti-inflammatory therapy is a logical approach to slowing the inevitable lung function deterioration in cystic fibrosis (CF) patients. This study's aim was to evaluate inflammatory markers and disease progression in paediatric CF patients chronically treated with azithromycin or low-dose prednisolone. Methods: The study included 204 patients with CF and 100 healthy controls; 102 CF patients were treated with basic therapy only (without anti-inflammatory treatment; WAT), and 102 individuals received basic therapy along with azithromycin (n = 59) or low-dose prednisolone (n = 43). The median duration of therapy was 24 months (range 12-82) with azithromycin and 31 months (range 12-180) with prednisolone. A cross-sectional analysis of plasma and sputum biomarkers was performed. Results: Compared with the healthy controls, the WAT group showed elevated IFN-γ, IL-10 (total), and TGFβ₁ concentrations, and decreased TNFα (total) and adrenocorticotropic hormone (ACTH) levels (all p < 0.05). Plasma TNFα (total) concentrations in azithromycin/prednisolone patients were significantly higher than those in WAT patients and similar to those of healthy children. In contrast, IL-10 (total) levels were significantly decreased in azithromycin/prednisolone-treated patients compared with WAT patients. Children from the azithromycin group demonstrated ACTH levels similar to those of healthy controls. Azithromycin-treated patients showed a significantly reduced rate of CF-related liver disease and a significantly increased incidence of glucose metabolism disturbances. Conclusions: Steady-state anti-inflammatory treatments may have a sustained immunomodulatory action at systemic and local levels in CF patients. Further investigations are needed to assess the effects of supportive azithromycin therapy on the hypothalamic-pituitary-adrenal axis and the incidence of non-pulmonary CF complications.

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