Assessment of stability and fluctuations of cultured lower airway bacterial communities in people with cystic fibrosis.

BACKGROUND: Routine clinical culture detects a subset of the cystic fibrosis (CF) airways microbiota based on culture-independent (molecular) methods. This study aimed to determine how extended sputum culture of viable bacteria changes over time in relation to clinical status and predicts exacerbations. METHODS: Sputa from patients at a baseline stable and up to three subsequent time-points were analysed by extended-quantitative culture; aerobe/anaerobe densities, ecological indexes and community structure were assessed together with clinical outcomes. RESULTS: Eighty patients were prospectively recruited. Sputa were successfully collected and cultured at 199/267 (74.5%) study visits. Eighty-two sputa from 25 patients comprised a complete sample-set for longitudinal analyses. Bacterial density, ecological indexes and clinical outcomes were unchanged in 18 patients with three sequential stable visits. Conversely, in 7 patients who had an exacerbation, total bacterial and aerobe densities differed over four study visits (P < .001) with this difference particularly apparent between the baseline visit and completion of acute antibiotic treatment where a decrease in density was observed. Bacterial communities were more similar within than between patients but stable patients had the least variation in community structure over time. Using logistic regression in a further analysis, baseline features in 37 patients without compared to 15 patients with a subsequent exacerbation showed that clinical measures rather than bacterial density or ecological indexes were independent predictors of an exacerbation. CONCLUSIONS: Greater fluctuation in the viable bacterial community during treatment of an exacerbation than between stable visits was observed. Extended-quantitative culture did not provide prognostic information of a future exacerbation.

Predictive validity of measurements of clinical competence using the team objective structured bedside assessment (TOSBA): assessing the clinical competence of final year medical students.

BACKGROUND: The importance of valid and reliable assessment of student competence and performance is gaining increased recognition. Provision of valid patient-based formative assessment is an increasing challenge for clinical teachers in a busy hospital setting. A formative assessment tool that reliably predicts performance in the summative setting would be of value to both students and teachers. AIM: This study explores the utility of the team objective structured bedside assessment (TOSBA), a novel ward-based formative assessment tool, in predicting student performance in the final clinical examination. METHODS: The performance of a cohort of final year students (n = 191) in the TOSBA was compared with their subsequent performance in the final examination. A comparison was also made between student performance in the existing formative assessment tool, the objective structured long examination record (OSLER) and the final examination. We also examined the relationship between the TOSBA and the components of the final examination using clustering around latent variables analysis. RESULTS: There was a clear relationship between student performance in the TOSBA and performance in the final examination (r(2) = 0.35). Student performance in the OSLER showed a poor relationship with performance in the final examination (r(2) = 0.15) compared with the TOSBA. The TOSBA results showed particular correlation with specific components of the final examination which were clinically based. CONCLUSION: TOSBA performance is a strong predictor of subsequent performance in the final examination. The clustering of the TOSBA with other assessments of clinical skills underlines its utility. Further research is required to determine whether performance in the TOSBA is predictive of subsequent performance during internship.