Is one month inhalation with inhaled tobramycin as effective as a 3 month treatment with two medicines (oral ciprofloxacin plus inhaled colistin; COMBI) for eradicating a new Pseudomonas infection?
Why is this important?
Infections with Pseudomonas aeruginosa occur in young CF patients and become more common with age. If early Pseudomonas infection is not treated, there is a high probability that patients will become chronically infected. Chronic lung infection leads to more respiratory symptoms, more treatment burden and worse lung disease compared to children without chronic Pseudomonas infection. If Pseudomonas is cultured for the first time (or again after a Pseudomonas free interval), antibiotic treatment can often efficiently eradicate it for several months to years.
The schedule used in our CF center is oral ciprofloxacin plus nebulized colistin for a period of three months. More recent studies have shown that 1 month treatment with high dose tobramycin for inhalation (TIS) is also effective for this purpose. Because the latter treatment is shorter and simpler we decided to compare both treatment regimens.
What did you do?
Children with a new Pseudomonas infection (after at least being free of Pseudomonas for 6 months) were asked to participate. They were randomly treated with one of the above treatments. We then evaluated how many patients were free of Pseudomonas at the end of treatment and how soon a Pseudomonas infection recurred.
What did you find?
Overall 58 patients participated in the study. Their mean age was 9 years and their mean lung function was 89% FEV1 % predicted. Pseudomonas was eradicated in almost 90% of patients in the COMBi group and 80% of patients in the TIS group and this was not statistically different. After eradication, a new Pseudomonas infection was detected after a mean period of 9 months in the COMBI group and 5 months in the TIS group. Although this looks quite different, statistically it was comparable. If a Pseudomonas infection recurred patients were again treated. Using these eradication treatments only 10% of patients had chronic Pseudomonas infections two years later.
What does this mean and reasons for caution?
Both treatments (inhaled tobramycin for one month and the combination of oral ciprofloxacin plus inhaled colistin for 3 months) were equally effective in eradicating early infection with Pseudomonas aeruginosa.
Most of the study patients already had 1 or more Pseudomonas infections in the past. In order to be able to participate in the study they only had to be Pseudomonas free for at least half a year which is not very strict. This may explain why many patients had recurrence of Pseudomonas infection. Our data show that repeated treatment for new isolation of Pseudomonas is efficient in preventing and postponing chronic Pseudomonas infection.
Many therapies seem efficient in eradicating new or recent Pseudomonas infection. Having more drugs available may be beneficial so that alternative strategies can be used after failure of one regimen or if the patient does not tolerate a specific treatment.