Inflammatory responses to individual microorganisms in the lungs of children with cystic fibrosis.

BACKGROUND: We hypothesized that the inflammatory response in the lungs of children with cystic fibrosis (CF) would vary with the type of infecting organism, being greatest with Pseudomonas aeruginosa and Staphylococcus aureus. METHODS: A microbiological surveillance program based on annual bronchoalveolar lavage (BAL) collected fluid for culture and assessment of inflammation was conducted. Primary analyses compared inflammation in samples that grew a single organism with uninfected samples in cross-sectional and longitudinal analyses. RESULTS: Results were available for 653 samples from 215 children with CF aged 24 days to 7 years. A single agent was associated with pulmonary infection (≥10(5) cfu/mL) in 67 BAL samples, with P. aeruginosa (n = 25), S. aureus (n = 17), and Aspergillus species (n = 19) being the most common. These microorganisms were associated with increased levels of inflammation, with P. aeruginosa being the most proinflammatory. Mixed oral flora (MOF) alone was isolated from 165 BAL samples from 112 patients, with 97 of these samples having a bacterial density ≥10(5) cfu/mL, and was associated with increased pulmonary inflammation (P < .001). For patients with current, but not past, infections there was an association with a greater inflammatory response, compared with those who were never infected (P < .05). However, previous infection with S. aureus was associated with a greater inflammatory response in subsequent BAL. CONCLUSIONS: Pulmonary infection with P. aeruginosa, S. aureus, or Aspergillus species and growth of MOF was associated with significant inflammatory responses in young children with CF. Our data support the use of specific surveillance and eradication programs for these organisms. The inflammatory response to MOF requires additional investigation.

A quantitative LightCycler PCR to detect Streptococcus pneumoniae in blood and CSF.

A quantitative real-time PCR targeting the Pneumolysin (ply) gene of Streptococcus pneumoniae was developed for the LightCycler instrument using Fluorescence Resonance Energy Transfer (FRET) probes. All common S. pneumoniae serotypes were detected while other bacteria and viruses were not. The sensitivity was determined to be between one and ten target copies per reaction. The PCR was applied to six CSF and 16 whole blood specimens from 17 patients with laboratory proven invasive pneumococcal disease. One hundred percent of CSF specimens and 69% of whole blood specimens were PCR positive. The bacterial loads were determined to be 7.6 to 6.01 x 10(5) copies/microL for the six CSF specimens, and 0.08 to 5.4 x 10(2) copies/microL for the 16 whole blood specimens. Ninety-seven percent of 30 culture and Gram's stain negative CSF specimens and 100% of 50 normal whole blood specimens were PCR negative. This highly sensitive and specific PCR assay has the potential to provide sufficiently rapid results to improve antibiotic treatment of S.pneumoniae infections, while bacterial load quantitation has opened up exciting possibilities for patient management.