title: Effects of Fluoroquinolones and Azithromycin on Biofilm Formation of Stenotrophomonas maltophilia.
abstract: Stenotrophomonas maltophilia is an opportunistic pathogen that causes respiratory and urinary tract infections, as well as wound infections in immunocompromised patients. This pathogen is difficult to treat due to increased resistance to many antimicrobial agents. We investigated the in vitro biofilm formation of S. maltophilia, including effects of fluoroquinolones (FQs) and azithromycin on biofilm formation. The organism initiated attachment to polystyrene surfaces after a 4 h incubation period, and reached maximal growth at 18-24 h. In the presence of FQs (moxifloxacin, levofloxacin or ciprofloxacin), the biofilm biomass was significantly reduced (P < 0.05). A lower concentration of moxifloxacin (10 μg/mL) exhibited a better inhibiting effect on biofilm formation than 100 μg/mL (P < 0.01), but with no difference in effect compared to the 50 μg/mL concentration (P > 0.05). However, the inhibitory effects of 10 μg/mL of levofloxacin or ciprofloxacin were slightly less pronounced than those of the higher concentrations. A combination of azithromycin and FQs significantly reduced the biofilm inhibiting effect on S. maltophilia preformed biofilms compared to azithromycin or FQs alone. We conclude that early use of clinically acceptable concentrations of FQs, especially moxifloxacin (10 μg/mL), may possibly inhibit biofilm formation by S. maltophilia. Our study provides an experimental basis for a possible optimal treatment strategy for S. maltophilia biofilm-related infections.
authors.affiliation: State Key Laboratory of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
authors.forename: Aihua
authors.initials: A
authors.lastname: Wang
authors.affiliation: Department of Respiratory Medicine, the First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, China.
authors.forename: Qinqin
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Centre for Infectious Diseases and Microbiology Services, ICPMR-Pathology West, Westmead Hospital, University of Sydney, Darcy Road, New South Wales, Australia.
authors.forename: Timothy
authors.initials: T
authors.lastname: Kudinha
authors.affiliation: State Key Laboratory of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
authors.forename: Shunian
authors.initials: S
authors.lastname: Xiao
authors.affiliation: State Key Laboratory of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Zhuo
mesh_terms: D017963:Azithromycin / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D024841:Fluoroquinolones / Q000494:pharmacology*; D020615:Stenotrophomonas maltophilia / Q000502:physiology*
chemical_list: D024841:Fluoroquinolones; D017963:Azithromycin