Risk factors for emergence of Stenotrophomonas maltophilia in cystic fibrosis.

The number of patients with cystic fibrosis (CF) whose sputum culture has yielded Stenotrophomonas maltophilia has increased in the last 5 years at St. Christopher's Hospital for Children. We conducted a case-control study to determine risk factors for recovery of S. maltophilia in respiratory secretions from patients with CF. We reviewed the outpatient and inpatient records of patients colonized with S. maltophilia between 1993 and 1997, and of age-matched (at time of initial recovery of S. maltophilia) control patients with CF who had never had a positive sputum culture for S. maltophilia. Variables included age at time of CF diagnosis, gender, severity of CF (based on Shwachman-Kulczycki (S-K) scores and spirometry), frequency of hospitalizations, use of oral, intravenous, or inhaled antibiotics, and use of oral or inhaled corticosteroids in the 2 years prior to the first isolation of S. maltophilia from respiratory secretions. Statistical methods included stepwise logistic regression to determine risk factors for acquisition of S. maltophilia. During the study period, 58 patients with CF had a positive sputum or deep throat culture for S. maltophilia. The distribution of S. maltophilia acquisition by year increased from 7 patients in 1993 (incidence, 2.8%) to 16 in 1997 (incidence, 6.2%). Patients positive for S. maltophilia were found to have significantly worse growth parameters, S-K score, and spirometric values than S. maltophilia-negative CF controls (P < 0.05). Stepwise logistic regression demonstrated that treatment with long-term antibiotics (P = 0.0016) and number of days of intravenous antibiotic therapy (P = 0.035) were significant risk factors for S. maltophilia colonization in our group of CF patients. We conclude that patients with CF whose respiratory secretions yield S. maltophilia have an overall worse clinical status at the time of initial S. maltophilia isolation than noncolonized patients, and that preceding treatment with antibiotics may have predisposed them to the acquisition of this bacterium in their respiratory secretions.

Quantitative bronchoscopic assessment of airway collapsibility in newborn lamb tracheae.

To date, quantitative studies of the inherent characteristics of the developing airway wall have required excision of an airway segment or surgical creation of an isolated segment. We hypothesized that airway wall characteristics, at various collapsing pressures, and attendant changes in stiffness after smooth muscle stimulation could be quantitated bronchoscopically from airway pressure-area relationships. Neonatal lamb tracheal segments (n = 12) were suspended over hollow mounts, in a buffer-filled chamber, and subjected to a range (0 to -4.0 kPa) of pressures to determine wall stiffness under collapsing forces before and after stimulation of the trachealis with methacholine. Luminal images were recorded through a 3.6-mm flexible bronchoscope under the same conditions, subsequently corrected for distortion, and a cross-sectional area was quantitated. Both pressure-volume and pressure-area relationships detected significant changes in airway wall stiffness after methacholine administration (p < 0.002), and the magnitude of change was similar between methods. These data suggest that quantitative flexible bronchoscopy can be used clinically in the intact airway to assess wall stiffness.

Antiemetic activity of ondansetron in acute gastroenteritis.

BACKGROUND: The mechanism of nausea and vomiting associated with gastroenteritis is unknown. The role of 5-HT3 receptors in emesis associated with gastroenteritis was investigated in paediatric patients. METHODS: A randomized, double-blind, placebo-controlled, parallel-group study was conducted in three groups of 12 patients each, receiving either a single i.v. dose of ondansetron (0.3 mg/kg), metoclopramide (0.3 mg/kg) or placebo (sterile saline). Food was restricted and oral rehydration was administered for 4 h. RESULTS: During 0-24 h, the number of emetic episodes experienced was significantly greater (P = 0.048) with placebo (mean = 5) than ondansetron (mean = 2) and the proportion of patients experiencing no emesis was significantly greater (P = 0.039) with ondansetron (58%) than placebo (17%). A numerical difference, in favour of ondansetron, was observed between ondansetron and metoclopramide groups for both of the above parameters. Fewer treatment failures were observed with ondansetron (17%) than placebo (33%) and metoclopramide (42 %). More diarrheal episodes were observed in the groups receiving anti-emetic treatment. All three treatments were well tolerated. CONCLUSIONS: Ondansetron, a 5HT3 receptor antagonist, was significantly superior to placebo in preventing emesis associated with acute gastroenteritis, in paediatric patients. Therefore, serotonin, acting through 5HT3 receptors, may play a role in this form of emesis.