title: Azithromycin and ciprofloxacin: a possible synergistic combination against Pseudomonas aeruginosa biofilm-associated urinary tract infections.
abstract: Biofilm formation is becoming a predominant feature in nosocomial infections. Since biofilms are increasingly resistant to antibiotics, making monotherapy ineffective, combination therapy appears to be relevant for their eradication. This study assessed the potential of azithromycin (AZM) and ciprofloxacin (CIP) alone and in combination in vitro and in a mouse model of urinary tract infection (UTI) induced with biofilm cells of Pseudomonas aeruginosa. In vitro antibacterial and antibiofilm activities of antibiotics alone and in combination were assessed using the fractional inhibitory concentration index (FICI), time-kill analysis and confocal laser scanning microscopy (CLSM). In vivo efficacy was evaluated in a UTI model by quantitation of bacterial burden in kidney and bladder tissue, renal histopathology, pathology index factors (MDA and NO), and pro-inflammatory (MIP-2 and IL-6) and anti-inflammatory (IL-10) cytokines. MICs of AZM and CIP for strain PAO1 were 256 and 0.5 μg/mL, respectively; MBECs were 4096 and 1024 μg/mL. Synergistic interaction was observed between AZM and CIP both against planktonic and biofilm bacteria (FICI<0.5). The combination was also able to inhibit biofilm formation (at MIC levels) as observed with CLSM. Oral therapy with AZM (500 mg/kg) and CIP (30 mg/kg) combination in mice for 4 days showed accelerated clearance of bacteria from kidney and bladder tissue, improved renal histopathology, decreased levels of MDA and NO, significant decline in MIP-2 and IL-6, and increased IL-10 in the kidney (P<0.0001). We conclude that AZM+CIP therapy holds promise against biofilm-associated UTIs as it confers antibacterial, immunomodulatory and anti-inflammatory effects.
authors.affiliation: Department of Microbiology, Basic Medical Sciences Block-I, South Campus, Panjab University, Chandigarh 160014, India.
authors.forename: Hina
authors.initials: H
authors.lastname: Saini
authors.affiliation: Department of Microbiology, Basic Medical Sciences Block-I, South Campus, Panjab University, Chandigarh 160014, India.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Chhibber
authors.affiliation: Department of Microbiology, Basic Medical Sciences Block-I, South Campus, Panjab University, Chandigarh 160014, India. Electronic address: kusum_harjai@hotmail.com.
authors.forename: Kusum
authors.initials: K
authors.lastname: Harjai
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D017963:Azithromycin / Q000494:pharmacology / Q000627:therapeutic use*; D058491:Bacterial Load; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002939:Ciprofloxacin / Q000494:pharmacology / Q000627:therapeutic use*; D016207:Cytokines / Q000032:analysis; D004195:Disease Models, Animal; D004359:Drug Therapy, Combination / Q000379:methods; D005260:Female; D006651:Histocytochemistry; D007668:Kidney / Q000382:microbiology / Q000473:pathology; D051379:Mice; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D018613:Microscopy, Confocal; D011552:Pseudomonas Infections / Q000188:drug therapy* / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000502:physiology; D016896:Treatment Outcome; D001743:Urinary Bladder / Q000382:microbiology; D014552:Urinary Tract Infections / Q000188:drug therapy* / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D016207:Cytokines; D002939:Ciprofloxacin; D017963:Azithromycin
keywords: Antibiofilm; Cytokines; FICI; Fractional inhibitory concentration index; Pathology index factors