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Case-control study of Stenotrophomonas maltophilia acquisition in cystic fibrosis patients. V. Marchac, A. Equi, C. Le Bihan-Benjamin, M. Hodson, A. Bush. #ERS Journals Ltd 2004. ABSTRACT: The aims of this case-control study were to describe the characteristics of cystic fibrosis (CF) patients who isolated Stenotrophomonas maltophilia in sputum, to determine risk factors for acquisition, to assess persistence of the organism and clinical outcomes postacquisition.Data were collected from 1991-1999. CF patients and controls (who had never isolated S. maltophilia) were matched for age (¡1 yr), sex and forced expiratory volume in one second (¡10%). Data were collected from the year prior and for 2 yrs postacquisition of S. maltophilia.The prevalence of S. maltophilia increased from 3.3% to 15%. Factors associated with S. maltophilia acquisition were more than two courses of intravenous antibiotics, isolation of Aspergillus fumigatus in sputum and oral steroid use. The effect of A. fumigatus was independent of steroid use. Clinical status did not change postacquisition. The majority of patients cleared the organism from the sputum.Long-term infection or an accelerated deterioration in lung function or nutrition is not likely post-Stenotrophomonas maltophilia acquisition in cystic fibrosis. This is the first documentation of an association between Aspergillus fumigatus isolation and Stenotrophomonas maltophilia acquisition in cystic fibrosis, independently of steroid therapy.

We audited prospectively 322 cough swabs taken from cystic fibrosis children and compared cough swabs with concomitant sputum samples in 30 expectorating patients. A positive cough swab is a strong predictor of sputum culture. However, a negative cough swab does not rule out infection. Persistent symptoms should be further investigated. (Arch Dis Child 2001;85:438-439) Keywords: cystic fibrosis; cough swabs; sputum; clinic Over the past two decades survival has improved in cystic fibrosis (CF), mainly as a result of aggressive antibiotic policies and improved nutrition. However, death is still principally caused by respiratory failure as a result of progressive suppurative lung disease. It is increasingly realised that early recognition and eradication of airway pathogens may delay the progression of lung disease. 1 The majority of older patients expectorate and as sputum cultures accurately reflect lower airway secretions, antibiotic therapy can be tailored to the results of the sputum culture.2 Younger patients do not usually expectorate and so cough swabs from the upper airway are often used in an attempt to reflect lower airway secretions. Information on the value of routine cough swabs is scanty. The aim of this study was to audit prospectively the cough swabs taken from non-expectorating patients over a period of six months. In order to determine the diagnostic accuracy of cough swabs we compared cough swabs with spontaneously expectorated sputum samples in a separate group of 30 expectorating patients. Subjects and methodsAll non-expectorating patients attending a paediatric CF clinic (age range 1.3-17 years) over a six month period had a cough swab performed. The physiotherapist obtained cough swabs by asking the patient to cough onto a cotton tipped swab placed in, but not touching the posterior pharynx. Patients were divided into two groups, symptomatic and non-symptomatic. Patients were placed in the non-symptomatic group if they had either no respiratory symptoms or no increase in usual symptoms. In a diVerent group of 30 productive adult patients, a cough swab was taken and then sputum was spontaneously expectorated. Samples were cultured for the common CF pathogens using the following media: heated blood agar, McConkey, Burkholderia Cepacia, Difco Pseudomonas, Sabaurauds Dextrose, and mannitol salt agar. Plates were incubated at 37°C and assessed at 24 and 48 hours. Antibiotics were commenced empirically at the clinic visit according to respiratory symptoms, but treatment was altered as directed by the result of the microbiological culture.Cough swabs were compared to sputum samples using a Bland Altman two by two contingency table.3 4 ResultsA total of 322 cough swabs were obtained from 161 patients; 87 (27%) patients were symptomatic and 235 (73%) were asymptomatic. Eighteen of 235 (8%) cough swabs from asymptomatic patients were positive and isolated the following organisms: Pseudomonas aeruginosa (n = 8), Staphylococcus aureus (n = 6), Haemophilus influenzae (n = 5). All these result...

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Several studies have reported clinical improvements in cystic fibrosis (CF) patients on macrolide antibiotics although the mechanism of action remains unclear. We conducted an open-label study of azithromycin (500 mg daily for 2 weeks) in 9 adult CF patients to explore 3 possible mechanisms: up-regulation of the multi-drug resistance (MDR) or cystic fibrosis transmembrane regulator (CFTR) proteins, correction of epithelial ion transport and reduced bacterial adherence. End-points included nasal potential difference (PD) measurements, nasal epithelial MDR and CFTR mRNA levels and Pseudomonas aeruginosa adherence to nasal epithelium. Forced expiratory volume in the 1st second (FEV(1)) increased significantly after 2 weeks of azithromycin (pre- 41.1 [5.0]%; post- 44.6 [5.8]%; P<0.05), although improvements in forced vital capacity (FVC) did not reach significance (pre- 61.3 [4.0]%; post- 67.1 [5.4]%, NS). Before treatment all subjects had nasal PD measurements characteristic of CF. Treatment led to no significant group differences in any measures of either sodium absorption or chloride secretion. Neither CFTR nor MDR mRNA levels had altered significantly and the adherence of P. aeruginosa did not decrease. We conclude that these are unlikely to be significant contributing mechanisms accounting for the consistent beneficial results observed in clinical trials of macrolides in CF.