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after blood tests, my 2.5 year old child was treated with Tobi then inhaled colimycin (because of bad tolerance of Tobi) for 3 months because blood results are very positive for pseudomonas but there is nothing in the sputum. .. but had ciprofloxacin for three weeks with tobi and still Pseudomonas negative in the Sputum but positive in blood test ... I do not understand why we find the pyo via the blood test but not via the spitting? What does it mean when one considers the cure iv? 7 months ago we discovered that there was Pseudomonas.
Thank you in advance for your reply
Your child has received antibiotic treatment of respiratory colonization with Pseudomonas (commonly known as Pseudomonas aeruginosa or Pyo) Ciprofloxacin and Tobi for 3 weeks followed by 3 months of inhaled colimycin. Early treatment, ie even in the absence of clinical signs of infection, is a major recommendation of the management of CF patients. Its aim is:
• to eradicate the germ before the infection grows and causes damage to the bronchi and lungs;
• to delay as much as possible re-colonization and the transition to chronic colonization/infection with this germ.
The effectiveness of treatment should be monitored by the disappearance of the germ in examination of sputum .
Serology has also been proposed for the early detection of first-colonization with Pseudomonas aeruginosa (Pa) and for monitoring the effectiveness of antibiotic therapy. Its principle is to detect an antibody in the blood which reflects the immune response of the organism to different compounds produced by the bacteria. This is therefore an indirect diagnosis.
At this stage, the data on the use of serology are contradictory in particular because of the lack of properly conducted studies and that different techniques (dosing different antibodies) are performed by laboratories making it difficult to compare results.
The latest publications on the subject state that:
• the primocolonization Pa is not always accompanied by anti-Pa positive serology
• conversely, anti-Pa serology may remain positive while the search of the germ is negative at ECBC. The latter case (which seems to be your child's) is the most common.
• the positive serology is not predictive of the first appearance of Pa in respiratory samples
• doubling the way certain antibodies (anti-exotoxin A and anti-protease) could be a predictor of re-infection Pa at shorter notice.
As you can see, the data are not conclusive at this stage of knowledge. The decision to implement a treatment uses a set of arguments (bacteriological, biological and clinical), which includes serology.
The reassuring elements for your child are his primary colonization was treated early and effectively (control ECBC remain negative): the intravenous antibiotic cure is considered only if there are general signs of infection or when the treatment by another route (oral, aerosol) has not been sufficiently effective.
Hoping to have answered your questions.
With best wishes for this new year.
Gilles RAULT, MD, Roscoff CF Center
With contributions from: Geneviève HERY-ARNAUD, Microbiology, University Hospital of Brest