Early Antibiotic Treatment Better to Eradicate New MRSA Infections in CF Patients, Study Suggests

Using antibiotics to fully eliminate new methicillin-resistant Staphylococcus aureus (MRSA) airway infections appears more effective than waiting for the infection to pass naturally in patients with cystic fibrosis (CF), a study reports.

In addition, this approach, recommended by the study’s researchers, may also provide benefits for the patient’s respiratory function and nutritional status.

The study, “Methicillin-resistant Staphylococcus aureus eradication in cystic fibrosis patients: A randomized multicenter study,” was published in the journal PLOS ONE.

Lung infections are a common problem in CF patients and a main cause of life-threatening complications. Most lung infections in these patients are caused by Staphylococcus aureus and Pseudomonas aeruginosa bacteria.

A type of antibiotic-resistant strain known as MRSA is of special concern as persistent infection with this bacterium “is associated with an increased rate of decline in lung function and higher mortality,” the researchers wrote.

There is no established gold standard for treating new-onset MRSA infections, and very few studies have analyzed protocols to eradicate this type of infection.

A research team at Anna Meyer Children’s University Hospital Cystic Fibrosis Center in Italy hypothesized that treating patients early to eliminate new MRSA infections is more effective than waiting for the body to clear the infection naturally.

To test their hypothesis, the team conducted an open-label trial (EudraCT number 2013-000219-25) with clinically stable CF patients, ages 4 or older, who were experiencing a new MRSA infection — this meant their airways had never tested positive for MRSA before, or they had the bacteria after a clearance period of 12 months.

Patients were randomized to one of two groups: 19 patients completed a 21-day treatment with a combination of antibiotics, specifically oral rifampicin (brand names Rifadine, Rifinah, and others) and oral trimethoprim/sulfamethoxazole (TMP/SMX; brand names Bactrim, Sulfatrim, and others), taken twice daily; 13 patients were enrolled in the observational group, which received no pharmacological treatment.

In the event of MRSA antibiotic resistance to TMP/SMX, patients in the treatment group (older than 8) were treated with rifampicin and minocycline (brand names Dynacin, Minocin, and others); if MRSA was resistant to rifampicin, they were given TMP/SMX and minocycline.

After six months, bacteria culture tests showed that MRSA had been eradicated in 12 out of 19 patients in the treatment group (63.2%). In comparison, five out of 13 patients who received no specific treatment cleared the bacteria naturally (38.5%). This translated into a 24.7% improvement in the proportion of MRSA clearance in the treatment group over the control group.

At the end of the six-month period, spirometry tests performed by most patients suggested that respiratory function had improved slightly more in the group who received antibiotic treatment. Mean FEV1 — forced expiratory volume in one second, how much air can be exhaled in one second after a deep inhaled breath — increased 7.13% in these patients, compared with an opposite trend in the control group, which had a 1.16% lower FEV1 value.

Additionally, antibiotic treatment was associated with some increase in patients’ body mass index (BMI), which may be a sign of a better nutritional status, in contrast with a slight decrease in BMI in the observational group. This difference, though, was not statistically significant.

No significant changes regarding the number of pulmonary exacerbations, days spent at the hospital, and use of antibiotics were observed between the two groups.

“In conclusion, the results of our study agree with previous experiences regarding the possibility of eradicating new-onset MRSA infection, and show favorable effects in CF patients’ FEV1 and BMI over a period of 6 months,” the researchers wrote.

“These results, together with other data from the literature and the low risk of side effects of the treatment, suggest that this strategy could be more widely implemented in the treatment of CF patients,” they concluded.