Treatments to clear the 'superbug' meticillin-resistant ... - Cochrane

Review question

We looked for evidence for the effects of different ways of clearing meticillin-resistant Staphylococcus aureus (MRSA), a so-called 'superbug', from the lungs of people with cystic fibrosis.

Background

MRSA is a type of bacteria resistant to some types of antibiotics (medicines that kill or inhibit bacteria). Because MRSA is hard to treat, it is sometimes called a 'superbug'. Infection with MRSA is particularly worrying for people with cystic fibrosis, an inherited condition which, amongst other things, causes thick mucus to build up in the lungs. It is very difficult for people with cystic fibrosis to cough up this thick mucus, making it an ideal breeding ground for bacteria, including MRSA, and making these people more prone to chest infections. It is thought that MRSA can cause more damage than other bacteria which are not resistant to antibiotics. We wanted to identify research evidence to support the best way for treating MRSA infections and also to see if this treatment would improve the lives of people with cystic fibrosis. This is an update of a previously published review.

Search date

The evidence is current to 31 January 2022.

Key results

We found three studies which included 135 people with cystic fibrosis and a diagnosed MRSA infection. 

Two studies (106 people) compared treatment given to one group of people versus observation only of a second group of people. In one of these studies, people in the active treatment group were given oral trimethoprim and sulfamethoxazole combined with rifampicin (all three are antibiotic medicines), plus additional decontamination treatment. In the second trial, people in the active treatment group were given two antibiotics orally (co-trimoxazole and rifampicin) and one by nose spray (mupirocin).

The results of these studies showed that clearing MRSA from the airways of people with cystic fibrosis is possible. In both trials, a larger proportion of those who were treated cleared MRSA. However, some people who were untreated also cleared MRSA spontaneously. Also, six months after treatment, the number of individuals who still had MRSA was not different between those who had received treatment and those who had not. We found no differences between treatment groups in quality of life, frequency of exacerbations (that is, flare-ups of the disease), unwanted or harmful effects of treatment, nasal colonisation with MRSA, or in changes in lung function or weight. The studies did not report the length of time until finding the next positive MRSA result in participants. In one of the studies, fewer people who were treated with antibiotics were admitted to hospital in the first 168 days. 

The third study compared treatment groups who were given either an inhaled antibiotic or an inhaled placebo (inactive substance). Both groups were also given the same oral antibiotics. In this study, there was no difference between groups in MRSA clearance. There were no differences between groups in lung function, quality of life, unwanted or harmful effects or nasal colonisation with MRSA. The trial did not report on change in weight or frequency of exacerbations. 

Treating MRSA early in people with cystic fibrosis has been shown to be possible, but it is not clear what longer-term implications this treatment will have.

Main limitations of the evidence

We had little or no confidence in the evidence we found for the different outcomes. This was due to potential issues from the study designs, where people knew which treatment each participant was receiving (groups were either given medication or just observed), and because there were small numbers of people in each study.