Achromobacter xylosoxidans in cystic fibrosis: prevalence and clinical relevance.
BACKGROUND
Achromobacter xylosoxidans is increasingly cultured in sputum from cystic fibrosis (CF) patients; nevertheless, there are few published data on the clinical impact of this infection or chronic colonisation.


METHODS
Relying on DNA fingerprinting techniques we studied the prevalence of A. xylosoxidans in our CF population. In a retrospective case control study the clinical status of patients with at least 3 sputum cultures positive for A. xylosoxidans over at least 9 months, at the moment of the first positive culture and during the period of colonisation were compared to age (+/-1 year), gender and to Pseudomonas aeruginosa colonisation controlled CF patients who had never A. xylosoxidans positive sputum cultures.


RESULTS
The prevalence of patients with at least one positive A. xylosoxidans culture was 17.9%. 5.3% of the patients fulfilled the criteria of our definition of colonisation. Colonised patients had a median age of 20 years (range 11-27 years) and a mean colonisation period of 1.5 (+/-0.9) years. At the moment of the first positive culture we found significantly lower Bhalla scores on HRCT scans of the lungs (11+/-3 versus 16+/-3, p<0.002), lower Brasfield chest X-ray scores (14+/-3 versus 18+/-3, p<0.019), lower FVC values (70%+/-22 versus 94%+/-12, p<0.017) and lower FEV(1) values (55%+/-32 versus 78%+/-23, p=0.123), although the latter did not reach significance. There was no significant difference in body mass index (BMI) (18.7+/-3 kg/m2 versus 19.6+/-3 kg/m2, p=0.8). Over the study period A. xylosoxidans-colonised patients did have more need for intravenous antibiotic treatment courses (19 versus 5, p<0.001); nevertheless, there was no significant difference in lung function decline over the study period (FVC: -6.25+/-12.34% versus -5.62+/-8.30%, p 0.77, FEV1: -5.62+/-8.30% versus -1.87+/-11.58%, p<0.47).


CONCLUSIONS
The prevalence of A. xylosoxidans infection or colonisation is probably underestimated. Colonised patients are mostly older, with more pronounced lung damage and lower lung function values. Although there was more need for intravenous antibiotic treatment courses, no faster decline in lung function was observed in A. xylosoxidans positive patients.
De Baets
Frans
F
Cystic Fibrosis Centre, University Hospital Ghent, De Pintelaan 185, 9000 Ghent, Belgium. frans.debaets@ugent.be
Schelstraete
Petra
P
Van Daele
Sabine
S
Haerynck
Filomeen
F
Vaneechoutte
Mario
M
D042441:Achromobacter denitrificans / Q000187:drug effects / Q000302:isolation & purification / Q000472:pathogenicity*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D016022:Case-Control Studies; D002648:Child; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000382:microbiology*; D005541:Forced Expiratory Volume; D016905:Gram-Negative Bacterial Infections / Q000150:complications / Q000188:drug therapy / Q000382:microbiology*; D006801:Humans; D011552:Pseudomonas Infections / Q000150:complications; D011550:Pseudomonas aeruginosa / Q000472:pathogenicity; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D013183:Sputum / Q000382:microbiology*
D000900:Anti-Bacterial Agents