Urine culture doubtful in determining etiology of diffuse symptoms among elderly individuals: a cross-sectional study of 32 nursing homes

Background: The high prevalence of bacteriuria in elderly individuals makes it difficult to know if a new symptom is related to bacteria in the urine. There are different views concerning this relationship and bacteriuria often leads to antibiotic treatments. The aim of this study was to investigate the relationship between bacteria in the urine and new or increased restlessness, fatigue, confusion, aggressiveness, not being herself/himself, dysuria, urgency and fever in individuals at nursing homes for elderly when statistically considering the high prevalence of asymptomatic bacteriuria in this population. Methods: In this cross-sectional study symptoms were registered and voided urine specimens were collected for urinary cultures from 651 elderly individuals. Logistic regressions were performed to evaluate the statistical correlation between bacteriuria and presence of a symptom at group level. To estimate the clinical relevance of statistical correlations at group level positive and negative etiological predictive values (EPV) were calculated. Results: Logistic regression indicated some correlations at group level. Aside from Escherichia coli in the urine and not being herself/himself existing at least one month, but less than three months, EPV indicated no clinically useful correlation between any symptoms in this study and findings of bacteriuria. Conclusions: Urinary cultures provide little or no useful information when evaluating diffuse symptoms among elderly residents of nursing homes. Either common urinary tract pathogens are irrelevant, or urine culture is an inappropriate test.