title: Molecular and Proteomic Analysis of Levofloxacin and Metronidazole ResistantHelicobacter pylori.
abstract: Antibiotic resistance in bacteria incurs fitness cost, but compensatory mechanisms may ameliorate the cost and sustain the resistance even under antibiotics-free conditions. The aim of this study was to determine compensatory mechanisms of antibiotic resistance inH. pylori. Five strains of levofloxacin-sensitiveH. pyloriwere inducedin vitroto develop resistance. In addition, four pairs of metronidazole-sensitive and -resistantH. pyloristrains were isolated from patients carrying dualH. pyloripopulations that consist of both sensitive and resistant phenotypes. Growth rate, virulence and biofilm-forming ability of the sensitive and resistant strains were compared to determine effects of compensatory response. Proteome profiles of paired sensitive and resistant strains were analyzed by liquid chromatography/mass spectrophotometry (LC/MS). Although there were no significant differences in growth rate between sensitive and resistant pairs, bacterial virulence (in terms of abilities to induce apoptosis and form biofilm) differs from pair to pair. These findings demonstrate the complex and strain-specific phenotypic changes in compensation for antibiotics resistance. Compensation forin vitroinduced levofloxacin resistance involving mutations ofgyrAandgyrBwas functionally random. Furthermore, higher protein translation and non-functional protein degradation capabilities in naturally-occuring dual population metronidazole sensitive-resistant strains may be a possible alternative mechanism underlying resistance to metronidazole without mutations inrdxAandfrxA. This may explain the lack of mutations in target genes in ~10% of metronidazole resistant strains.
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia.
authors.forename: Aimi
authors.initials: A
authors.lastname: Hanafi
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia.
authors.forename: Woon Ching
authors.initials: WC
authors.lastname: Lee
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, University of MalayaKuala Lumpur, Malaysia; Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of SingaporeSingapore, Singapore.
authors.forename: Mun Fai
authors.initials: MF
authors.lastname: Loke
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia.
authors.forename: Xinsheng
authors.initials: X
authors.lastname: Teh
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia.
authors.forename: Ain
authors.initials: A
authors.lastname: Shaari
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia.
authors.forename: Mojdeh
authors.initials: M
authors.lastname: Dinarvand
authors.affiliation: Laboratoire de Bactériologie, Université de BordeauxBordeaux, France; Institut National de la Santé et de la Recherche Médicale U853Bordeaux, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Lehours
authors.affiliation: Laboratoire de Bactériologie, Université de BordeauxBordeaux, France; Institut National de la Santé et de la Recherche Médicale U853Bordeaux, France.
authors.forename: Francis
authors.initials: F
authors.lastname: Mégraud
authors.affiliation: Department of Medicine, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia.
authors.forename: Alex Hwong Ruey
authors.initials: AH
authors.lastname: Leow
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia.
authors.forename: Jamuna
authors.initials: J
authors.lastname: Vadivelu
authors.affiliation: Department of Medicine, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia.
authors.forename: Khean Lee
authors.initials: KL
authors.lastname: Goh
keywords: Helicobacter pylori; antibiotic resistance; bacterial fitness; levofloxacin; metronidazole; proteome