title: Acid aspiration induces bacterial pneumonia by enhanced bacterial adherence in mice.
abstract: The issue of whether acid aspiration facilitates bacterial pneumonia caused by Pseudomonas aeruginosa by enhanced bacterial adherence was examined in mice. Survival or the number of bacteria in lung tissues was evaluated after an intratracheal challenge of hydrochloric acid (HCl), a sublethal dose of P. aeruginosa, or both in mice. Bacterial adherence to the tracheal epithelium after acid aspiration was also examined by scanning electron microscopy. A simultaneous intratracheal challenge of 50 microl of 10(-1) N HCl, but not 10(-2) to 10(-4) N HCl, combined with a sublethal dose of P. aeruginosa significantly increased the number of bacteria in the lung tissues and decreased survival, while all mice that received either HCl or P. aeruginosa survived. Significantly higher numbers of adherent bacteria on the tracheal epithelium were found in mice that received 10(-1)N HCl, compared with mice that received HCl (10(-2) to 10(-4) N) or saline. These data indicate that acid aspiration induced airway epithelial injury and enhanced P. aeruginosa adherence to the epithelium, and led to the subsequent development of bacterial pneumonia in mice. Enhanced bacterial adherence on the acid-injured epithelium may explain fatal bacterial pneumonias in patients with respiratory aspiration of gastric contents.
authors.affiliation: Department of Internal Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, 852-8523, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Mitsushima
authors.forename: Kazunori
authors.initials: K
authors.lastname: Oishi
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Nagao
authors.forename: Akitoyo
authors.initials: A
authors.lastname: Ichinose
authors.forename: Masachika
authors.initials: M
authors.lastname: Senba
authors.forename: Takuya
authors.initials: T
authors.lastname: Iwasaki
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Nagatake
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D015169:Colony Count, Microbial; D006851:Hydrochloric Acid / Q000008:administration & dosage; D008168:Lung / Q000382:microbiology / Q000473:pathology / Q000648:ultrastructure; D051379:Mice; D008855:Microscopy, Electron, Scanning; D011015:Pneumonia, Aspiration / Q000209:etiology* / Q000382:microbiology / Q000473:pathology; D018410:Pneumonia, Bacterial / Q000209:etiology* / Q000382:microbiology / Q000473:pathology; D011552:Pseudomonas Infections / Q000209:etiology* / Q000382:microbiology / Q000473:pathology; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification / Q000472:pathogenicity* / Q000648:ultrastructure; D020545:Respiratory Mucosa / Q000378:metabolism / Q000648:ultrastructure; D013997:Time Factors
chemical_list: D006851:Hydrochloric Acid