Methicillin-resistant Staphylococcus aureus in cystic fibrosis patients: do we need to care? A cohort study

Abstract

CONTEXT AND OBJECTIVE: The prevalence of a variety of potentially pathogenic microorganisms in cystic fibrosis patients, such as methicillin-resistant Staphylococcus aureus (MRSA), has increased over the past decade. Given the increasing prevalence of MRSA and the few data available in the literature, better understanding of the clinical repercussions of colonization by this bacterium in cystic fibrosis patients becomes essential. This study aimed to evaluate the repercussions of chronic colonization by MRSA in cystic fibrosis patients. DESIGN AND SETTING: Retrospective cohort study from January 2004 to December 2013 in a cystic fibrosis reference center. METHODS: Each patient with cystic fibrosis was evaluated for nutritional status (body mass index, BMI, and BMI percentile), pulmonary function and tomographic abnormalities (modified Bhalla scores) at the time of chronic colonization by MRSA or methicillin-susceptible Staphylococcus aureus (MSSA) and throughout the study period. RESULTS: Twenty pairs of patients were included. There were no significant differences between the groups regarding nutritional characteristics. Spirometric data showed a trend towards greater obstruction of the airways in patients with MRSA. Patients with MRSA presented greater structural damage to their lungs, demonstrated not only by the total Bhalla score but also by its parameters individually. CONCLUSIONS: Patients colonized by MRSA presented greater functional and structural respiratory impairment at the time of chronic colonization. Disease progression was also faster in patients chronically colonized by MRSA than in those with MSSA. This was shown through comparisons that avoided possible confounding variables.

Molecular characterisation of methicillin-resistant Staphylococcus aureus from chronically colonised cystic fibrosis paediatric patients in Brazil

“…Staphylococcus aureus is one of the earliest and most prevalent pathogens isolated from the airways of CF patients. Colonisation with methicillin-resistant S. aureus (MRSA) has risen dramatically over the past decade [2] and has been associated with poor clinical outcomes in these patients [3]. According to the Brazilian Cystic Fibrosis Registry 2017, MRSA was the seventh most common microorganism isolated from respiratory cultures of CF patients [4].…”

High-resolution computed tomography findings in young infants with cystic fibrosis detected by newborn screening

“…These authors speculated that the absence of an association between early P. aeruginosa infection and abnormal subsequent chest CT findings may be attributed to aggressive treatment. Other studies including adolescent or older patients chronically colonized with methicillin-resistant Staphylococcus aureus or P. aeruginosa identified increased total modified Bhalla scores, reflecting the presence of structural lung disease (14,15). Another study on the isolation of proinflammatory pathogens ( P. aeruginosa , Streptococcus pneumoniae and Aspergillus species) in bronchoalveolar lavage fluid showed a relationship between infection status with these pathogens and CT findings in infants (29).…”

“…The total score could range from zero (absence of abnormalities) to 37 (all abnormalities present and severe). The modified Bhalla score was previously validated in CF patients in another study at this institution (14) and was subsequently established not only for clinical studies but also for patient follow-up (15,25).…”

“…The development of high-resolution computed tomography (HRCT) has allowed the early detection of pathological changes in lung parenchyma as well as in the proximal and distal airways (bronchial wall thickening, bronchiectasis, mucoid impaction and lung hyperinflation) (11). Reproducible scoring systems can be used to quantify CT findings (14,15). Furthermore, some studies that used HRCT scoring systems for children and adults with CF and well-established lung disease demonstrated more severe bronchiectasis in the upper lobes (16-18).…”

Staphylococcus aureus in cystic fibrosis

“…There is an emerging consensus that MRSA is an important pathogen in CF rather than simply a marker of severe disease 37 *. A recent case control study from Brazil 38 has shown that patients infected with MRSA have a greater respiratory impairment at the time of chronic infection and disease progression is more rapid in patients with MRSA compared to those with sensitive strains of S. aureus. CF patients with MRSA have also been shown to have worse CT appearances than those who are free of infection 39 .…”