PURPOSE:S.maltophilia is a multi-antibiotic-resistant organism being isolated with increasing frequency from the sputa of patients with cystic fibrosis (CF). Patterns of S.maltophilia acquisition and its clinical significance remain unclear.
METHODS:Analysis of the incidence, associations, and treatment of S.maltophilia isolates in the sputa of CF patients at a major CF center.
RESULTS:199 (74 adult, 125 pediatric) patients with CF were evaluated. In 2005–06, 25 (9 adult, 16 pediatric) patients grew S.maltophilia in their sputa for the first time (incidence rate 15.24%). Prevalence, which had been 17.6% prior to 2005, increased to 30.2%. DNA fingerprinting showed no clustering of strains indicating that the new acquisitions were independent and not cross-infections from a point source. Median age for converters was not significantly different from the total population. Baseline FEV1 was also similar between the two –new converters: adults 51%, children 98% predicted; total: adults 46%, children 100 % predicted. At 18 months follow-up, there was no significant decline in FEV1 among the new converters - FEV1 (mean ± SD) baseline: 84 ± 31% predicted; follow-up: 80 ± 24% predicted, p:0.32. 62.5% of new converters received antibiotics in the six months preceding initial isolation of S.maltophilia. There was notable seasonal variation in the rate of acquiring S.maltophilia –fall: 44%; winter: 32%; summer: 16%; spring: 8%. New isolation of S.maltophilia prompted treatment in 44% of all new converters. At 18 months follow-up, 24% had cleared S.maltophilia on subsequent cultures.
CONCLUSION:There has been an increase in S.maltophilia in our CF center in both adult and pediatric populations. This appears to be due to new acquisitions rather than cross infection. Baseline FEV1 and prior antibiotic use do not seem to be predisposing factors. Even though there was no measurable impact of S.maltophilia on lung function, new acquisition prompted treatment in 44% of patients.
CLINICAL IMPLICATIONS:Larger-scale studies with longer follow up are warranted to determine impact of S.maltophilia on lung function and need for treatment.
DISCLOSURE:Subani Chandra, No Financial Disclosure Information; No Product/Research Disclosure Information