Can Cystic Fibrosis Patient Mobility be a Risk Factor for Pseudomonas Aeruginosa Infection?

Researchers at the University of Queensland in Australia recently reported that the mobility of cystic fibrosis (CF) patients between care centers increases the risk of transmission of the associated bacterial Pseudomonas aeruginosa infection. The study was published in the journal The Lancet Respiratory Medicine and is entitled “The social network of cystic fibrosis centre care and shared Pseudomonas aeruginosa strain infection: a cross-sectional analysis.”

CF is a rare, life-threatening genetic disease in which a defective gene (CFTR) induces a salt imbalance, causing the body to form unusually thick, sticky mucus that can obstruct the airways and promote dangerous lung infections, resulting in serious respiratory and also gastrointestinal manifestations. CF can affect the cells that produce mucus, sweat and digestive juices. Microbial infections are the major cause of morbidity and mortality in CF patients. Bacteria such as P. aeruginosa can induce chronic pulmonary infections and a serious inflammatory response, leading to respiratory failure and early death in CF patients. There is no cure for the disease and it is estimated that almost 75,000 individuals worldwide suffer from CF, including 30,000 individuals in the United States.

CF patients are thought to acquire P. aeruginosa through person-to-person transmission. Interestingly, cross-infection of shared cystic-fibrosis-specific P. aeruginosa strains has been reported across large geographical distances indicating wide dissemination of the pathogen. In the study, researchers assessed the extent to which the movement of CF patients infected with P. aeruginosa between CF centers contributes to bacterial dissemination.

The team analyzed data from CF patients infected with P. aeruginosa attending 18 different Australian CF centers between September 2007 and June 2010. Social network analysis was employed to assess the spread of P. aeruginosa infection among the patients. The predominant Australian strains are known to be AUST-01 and AUST-02.

In total, researchers assessed 983 CF patients (mean age of 25 years) from whom they isolated and identified 531 distinct genotypes of P. aeruginosa. Of these genotypes, 493 were found to be unique strains in 373 patients, whereas 38 were shared strains in 610 patients. Based on their model, researchers concluded that the mobility of CF patients within CF centers is a potential key risk factor for the acquisition of shared P. aeruginosa strain infections.

“Our study shows that the movement of patients with cystic fibrosis between different health care settings seems to be an important risk factor for the acquisition of transmissible P. aeruginosa infections,” concluded the study’s lead author Dr. Timothy J. Kidd in a news release. “These results show the importance of prioritizing infection control interventions, including prospective molecular surveillance, strict infection control, hospital design and ventilation to limit cross-infection.”