Hispanic individuals with cystic fibrosis (CF) younger than 25 years of age have an increased risk for acquiring methicillin-sensitive Staphylococcus aureus (MSSA) and acquire MSSA and methicillin-resistant SA (MRSA) at an earlier age, according to study findings published in the Journal of Cystic Fibrosis.
Previous research has indicated that among people with CF (pwCF), those who are Hispanic vs non-Hispanic and White have lower pulmonary function, lower percent predicted forced expiratory volume in the first second, and up to 2.8 times higher risk of mortality. Research has also shown that people with cystic fibrosis who are Hispanic are at increased risk for contracting Pseudomonas aeruginosa, which may evolve into a more severe form.
Investigators conducted a longitudinal cohort study to determine differences in the timing and acquisition risk for Staphylococcus aureus (S aureus) in Hispanic vs non-Hispanic White individuals with CF. Primary endpoints were age at acquiring S aureus, incident MSSA, incident MRSA, and transition from intermittent to persistent MRSA. Investigators defined persistent MRSA as at least 3 positive respiratory cultures for MRSA during follow-up.
Investigators reviewed data collected between 2008 and 2013 on people with CF in the US CF Foundation Patient Registry (CFFPR), which includes more than 80% of people in the US with CF. The researchers compared Hispanic vs non-Hispanic White people with CF with respect to how frequently they contracted MSSA, MRSA, and persistent MRSA.
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These results add to the evidence that the disease course in Hispanic pwCF is more severe than in non-Hispanic White pwCF.
Among the 10,640 people with CF whose data were reviewed by the researchers, 7.5% were Hispanic and 92.5% were non-Hispanic White. Those who were Hispanic had less frequent pancreatic sufficiency and were more likely to have mild CF transmembrane receptor (CFTR) variants or unknown/unclassified variants.
No statistically significant between-ethnicity differences were found in sex, CF-related diabetes, or age at enrollment into the CFFPR.
Risk of contracting MSSA was 19% higher and risk of contracting MRSA was 13% higher in Hispanic people with CF (hazard ratio [HR] 1.19; 95% CI, 1.10-1.28; P <.001) vs non-Hispanic White people with CF (HR, 1.13; 95% CI, 1.02-1.26; P =.02).
The investigators found no statistically significant between-ethnicity difference in persistent MRSA (HR, 1.01; 95% CI, 0.89-1.16; P =.8).
Using multivariate Cox models and adjusting among other aspects for sex, age, and CF-related diabetes, the investigators noted a significant association with ethnicity for the risk of MSSA only.
Hispanic vs non-Hispanic White people with CF had younger median ages for contracting MSSA (3.8 years vs 4.9 years; P <.001) and MRSA (20.8 years vs 22.4 years; P =.02).
Study limitations include lack of applicability of study findings to Hispanic people with CF living outside the US. Also, the generalizability of study findings is limited by the use of data from the CFFPR that was gathered prior to widespread use of CFTR modulators.
The investigators concluded that Hispanic people with CF contract MSSA and MRSA “at an earlier age and are at increased overall risk of acquiring MSSA and MRSA but not developing persistent MRSA.” They further added that “Ethnic differences in pulmonary pathogens may contribute to increased morbidity and mortality in Hispanic pwCF.” The study authors concluded, “These results add to the evidence that the disease course in Hispanic pwCF is more severe than in non-Hispanic White pwCF.”
