title: Assessment of combination therapy in BALB/c mice injected with carbapenem-resistant Enterobacteriaceae strains.
abstract: Monotherapeutic options for carbapenem resistant infections are limited. Studies suggest that combination therapy may be associated with better outcomes than monotherapies. However, this is still controversial. This study assessed, the efficacy of combination therapy against carbapenem resistant Enterobacteriaceae harboring singly various extended spectrum beta lactamase or carbapenemase encoding genes. Thus, four isolates harboring either bla CTXM-15, bla CTXM-15 and bla OXA-48, bla NDM-1, or bla KPC-2 genes were selected for testing. Minimal inhibitory concentration was determined by broth dilution method. Gene transcript levels on single and combined treatments were done in vitro and in vivo by qRT-PCR. Assessment of treatments was done in BALB/c mice according to a specific protocol. As such, the qRT-PCR revealed a significant decrease of transcript levels in all isolates upon using rifampicin or tigecycline, singly or in combination with colistin. However, variable levels were obtained using colistin singly or in combination with meropenem or fosfomycin. In vivo assessment showed that all combinations used were effective against isolates harboring bla CTXM-15, bla OXA-48, and bla NDM-1. Conversely, the most significant combination against the isolate harboring bla KPC-2 gene was colistin with either carbapenem, fosfomycin, or kanamycin. As a conclusion, combination therapy selected based on the type of carbapenemase produced, appeared to be non-toxic and might be effective in BALB/c mice. Therefore, the use of a rationally optimized combination therapy might lead to better results than monotherapy, however, clinical trials are needed for human consumption.
authors.affiliation: Department of Experimental Pathology, Immunology and Microbiology, Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut Beirut, Lebanon.
authors.forename: Noor A
authors.initials: NA
authors.lastname: Salloum
authors.affiliation: Department of Experimental Pathology, Immunology and Microbiology, Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut Beirut, Lebanon.
authors.forename: Kohar Annie B
authors.initials: KA
authors.lastname: Kissoyan
authors.affiliation: Department of Experimental Pathology, Immunology and Microbiology, Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut Beirut, Lebanon.
authors.forename: Sukayna
authors.initials: S
authors.lastname: Fadlallah
authors.affiliation: Department of Experimental Pathology, Immunology and Microbiology, Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut Beirut, Lebanon.
authors.forename: Katia
authors.initials: K
authors.lastname: Cheaito
authors.affiliation: Pathology and Laboratory Medicine, Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut Beirut, Lebanon.
authors.forename: George F
authors.initials: GF
authors.lastname: Araj
authors.affiliation: Pediatrics and Adolescent Medicine, Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut Beirut, Lebanon.
authors.forename: Rima
authors.initials: R
authors.lastname: Wakim
authors.affiliation: Internal Medicine, Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut Beirut, Lebanon.
authors.forename: Souha
authors.initials: S
authors.lastname: Kanj
authors.affiliation: Internal Medicine, Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut Beirut, Lebanon.
authors.forename: Zeina
authors.initials: Z
authors.lastname: Kanafani
authors.affiliation: Pediatrics and Adolescent Medicine, Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut Beirut, Lebanon.
authors.forename: Ghassan
authors.initials: G
authors.lastname: Dbaibo
authors.affiliation: Department of Experimental Pathology, Immunology and Microbiology, Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut Beirut, Lebanon.
authors.forename: Ghassan M
authors.initials: GM
authors.lastname: Matar
keywords: Enterobacteriaceae; carbapenem resistance; carbapenemase; combination therapy; gene transcript; in vivo