Long Term Chronic <em>Pseudomonas aeruginosa</em> Airway Infection in Mice

Abstract

A mouse model of chronic airway infection is a key asset in cystic fibrosis (CF) research, although there are a number of concerns regarding the model itself. Early phases of inflammation and infection have been widely studied by using the Pseudomonas aeruginosa agar-beads mouse model, while only few reports have focused on the long-term chronic infection in vivo. The main challenge for long term chronic infection remains the low bacterial burden by P. aeruginosa and the low percentage of infected mice weeks after challenge, indicating that bacterial cells are progressively cleared by the host. This paper presents a method for obtaining efficient long-term chronic infection in mice. This method is based on the embedding of the P. aeruginosa clinical strains in the agar-beads in vitro, followed by intratracheal instillation in C57Bl/6NCrl mice. Bilateral lung infection is associated with several measurable read-outs including weight loss, mortality, chronic infection, and inflammatory response. The P. aeruginosa RP73 clinical strain was preferred over the PAO1 reference laboratory strain since it resulted in a comparatively lower mortality, more severe lesions, and higher chronic infection. P. aeruginosa colonization may persist in the lung for over three months. Murine lung pathology resembles that of CF patients with advanced chronic pulmonary disease.This murine model most closely mimics the course of the human disease and can be used both for studies on the pathogenesis and for the evaluation of novel therapies. Video LinkThe video component of this article can be found at

Efficacy of the Novel Antibiotic POL7001 in Preclinical Models of Pseudomonas aeruginosa Pneumonia

“…In order to investigate the efficacy of POL7001 in a chronic infection environment similar to the one characteristic of lungs of CF patients, mice were infected with MDR-RP73 embedded in agar beads and inoculated i.t. according to established procedures (13,24). In order to perform endotracheal drug administration, a MicroSprayer Aerosolizer from Penn-Century was used.…”

“…Immunocompetent C57Bl/ 6NCrlBR male mice (8 to 10 weeks of age) from Charles River and gutcorrected CF transmembrane conductance regulator (CFTR)-deficient male C57BL/6 Cftr tm1UNC TgN(FABPCFTR)#Jaw mice and the corresponding congenic wild-type (wt) mice (11 to 18 weeks of age) (12), obtained from Case Western Reserve University and maintained at San Raffaele Scientific Institute (Milan, Italy), were used. Mice were infected with 1 ϫ 10 7 CFU of the planktonic multidrug-resistant (MDR)-RP73 strain for acute infection or 1 ϫ 10 6 CFU of the strain embedded in agar beads for chronic infection, as previously described (10,13,14). After infection, mice were treated with antibiotics or saline solution and monitored for body weight according to the schedule shown in Fig.…”

“…Thus, not all outcome measures were the same for each experiment. Lung CFU, counts of cytokines or chemokines, and bronchoalveolar lavage fluid (BALF) cell counts were analyzed as previously described (13,17).…”

Lentiviral Vector Gene Therapy Protects XCGD Mice From Acute Staphylococcus aureus Pneumonia and Inflammatory Response

“…In another group of mice, lungs were excised and used for histopathology or excised after BAL collection, homogenized and plated onto TBS-agar plates for CFU counting. 50 BAL collection and analysis. BAL was collected with a 22-g venous catheter by washing the lungs with 3 ml of RPMI-1640 (Euroclone, Milan, Italy) with protease inhibitors (Complete tablets, Roche Diagnostic, Basel, Switzerland) as previously described.…”

“…BAL was collected with a 22-g venous catheter by washing the lungs with 3 ml of RPMI-1640 (Euroclone, Milan, Italy) with protease inhibitors (Complete tablets, Roche Diagnostic, Basel, Switzerland) as previously described. 50 Total cells present in the BAL were counted, and a differential cell count was performed on cytospins stained with Diff Quick (Dade, Biomap, Italy). BAL was serially diluted and plated on tryptic soy broth-agar plates.…”