Effects of Tigecycline Combined with Azithromycin Against Biofilms of Multidrug-Resistant Stenotrophomonas maltophilia Isolates from a Patient in China

Abstract

Purpose Our aim was to investigate in vitro biofilm formation by S. maltophilia and the effects of antibacterial agents used to prevent biofilm formation. Methods Two trimethoprim/sulfamethoxazole-resistant S. maltophilia strains were isolated from the pleural effusion of a patient with cancer. The minimum inhibitory concentrations (MICs) of amikacin, azithromycin, cefoperazone/sulbactam, and tigecycline were determined. The checkerboard method was used to determine the fractional inhibitory concentration indices (FICIs). A crystal violet biofilm assay and confocal laser scanning microscopy (CLSM) were used to observe biofilm formation. In vitro effects of azithromycin combined with tigecycline on biofilms of S. maltophilia strains were tested. Results The two S. maltophilia isolates were confirmed to produce strong biofilms. Crystal violet biofilm assay and CLSM analysis of S. maltophilia biofilm were in the initial adhesive stage after 2 h incubation. Biofilm was in the exponential phase of growth at 12 h and reached maximal growth at 36–48 h. Compared with tigecycline or azithromycin alone, the combination of tigecycline and azithromycin increased the inhibiting effect S. maltophilia biofilm biomass after incubation for 12 h. Compared with the control group, in almost all strains treated with tigecycline and azithromycin, the biofilm was significantly suppressed significance (P<0.001). We found that 2x MIC azithromycin combined with 1x MIC tigecycline had the best inhibiting effect against the biofilm, the biofilm inhibition rates of three strains were all over 60%, the biofilm thickness was inhibited from 36.00 ± 4.00 μm to 8.00 μm, from 40.00 μm to 6.67± 2.31 μm, and from 32.00 μm to 13.33 ± 2.31 μm in SMA1, SMA2 and ATCC17666, respectively. Conclusion Azithromycin combined with tigecycline inhibited biofilm formation by S. maltophilia . Our study provides an experimental basis for a possible optimal treatment strategy for S. maltophilia biofilm-related infections.

Novel synergistic combinations of last-line antibiotics and FDA-approved drugs against Klebsiella pneumoniae revealed by in vitro synergy screenings

“…We validated the synergistic interaction of azithromycin in combination with all three PCs. This was in agreement with several studies reporting the bactericidal and antibiofilm action of azithromycin combined with tigecycline (59), and colistin (60,61) against different Gram-negative bacilli. The interaction with fosfomycin is novel.…”

Effects of Tigecycline combined with Cefoperazone on bacterial clearance and serum biochemical indexes in patients with pulmonary infections in ICU

“…This addition further improves the antibacterial effect of tigecycline against pan drugresistant pathogens. 10,11 However, tigecycline is widely distributed in tissues, resulting in relatively low blood drug concentrations. Consequently, tigecycline benefits from a combined strategy with other drugs to maximize therapeutic effect while minimizing drug resistance.…”

Antimicrobial Susceptibility, Minimum Inhibitory Concentrations, and Clinical Profiles of Stenotrophomonas maltophilia Endophthalmitis

“…A similar finding was reported by Wu et al [ 28 ], who determined the MIC 90 for tigecycline to be 1 μg/mL for S. maltophilia . Yue et al [ 29 ] demonstrated that a combination of tigecycline and azithromycin can successfully inhibit the formation of an S. maltophilia biofilm. Given the results of our study, tigecycline may be another effective treatment option for S. maltophilia infections.…”