title: Enhancement of antibiotic susceptibility of  Stenotrophomonas maltophilia  using a polyclonal antibody developed against an ABC multidrug efflux pump.
abstract: Stenotrophomonas maltophilia is an emerging nosocomial pathogen capable of causing healthcare-associated infections, including pneumonia and bacteremia. Intrinsic resistance in S. maltophilia is exhibited towards many broad-spectrum antibiotics, and treatment recommendations are controversial. One of the major causes of antimicrobial resistance is attributed to a robust array of efflux pumps that extrude drug compounds from the cell. Using checkerboard and growth kinetic assays, we evaluated the in vitro activity of a polyclonal antibody raised against an ATP-binding cassette efflux protein in S. maltophilia. Six clinical strains of S. maltophilia and one type strain were challenged with co-trimoxazole, ticarcillin-clavulanate, and ciprofloxacin, alone and in combination with antibody. One clinical strain was tested by growth curve experiments for each antibiotic-antibody combination. The use of antibody resulted in significantly increased susceptibility in 71.4% (15/21) of treatments tested, with 33.3% displaying synergy and 38.1% an additive effect. In growth kinetic studies, synergy was obtained for each antibiotic-antibody combination. Thus, the use of antibody raised against multidrug efflux pumps for the treatment of multidrug-resistant organisms warrants further investigation. Antibody targeting substrate recognition sites, or other functionally important epitopes, may lead to inhibition of multiple efflux pumps that share the same substrate and is an attractive area that should be explored.
authors.affiliation: Medical Microbiology, School of Medicine, University of Manchester, Manchester Royal Infirmary, UK. arifhamad@doctors.org.uk
authors.forename: Arif
authors.initials: A
authors.lastname: Al-Hamad
authors.forename: James
authors.initials: J
authors.lastname: Burnie
authors.forename: Mathew
authors.initials: M
authors.lastname: Upton
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000378:metabolism; D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000494:pharmacology*; D000907:Antibodies, Bacterial / Q000276:immunology* / Q000378:metabolism; D002939:Ciprofloxacin / Q000378:metabolism / Q000494:pharmacology; D002969:Clavulanic Acids / Q000378:metabolism / Q000494:pharmacology; D004357:Drug Synergism; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D011817:Rabbits; D020615:Stenotrophomonas maltophilia / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism; D013982:Ticarcillin / Q000378:metabolism / Q000494:pharmacology; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000378:metabolism / Q000494:pharmacology
chemical_list: D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D000907:Antibodies, Bacterial; D002969:Clavulanic Acids; D002939:Ciprofloxacin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; C043215:ticarcillin-clavulanic acid; D013982:Ticarcillin