Are c-reactive protein and procalcitonin effective biomarkers for urinary tract infection in elderly patients? what should be administered for empiricial treatment?

Introduction: In the absence of typical overt symptoms, diagnosis of urinary tract infection is more difficult in elderly individuals. This study investigated the benefits of C-reactive protein, procalcitonin, and leukocyte levels in supporting the diagnosis of urinary tract infection in the elderly and causative factors.Materials and Method: A retrospective examination of information from a hospital data system of patients > 65 years of age, who were diagnosed with urinary tract infection in a 4-year period, was performed. Bacterial identification and antibiotic susceptibility tests were performed.Results: In the case group, procalcitonin and C-reactive protein levels were higher than those in the control group, and a moderately positive correlation with urinary tract infection was found (p<0.001, r=0.454). Although procalcitonin was a better predictor than C-reactive protein , the risk criteria for C-reactive protein were also very close to those of procalcitonin. The cut-off values for C-reactive protein and procalcitonin were 6.93 mg/L and 0.075 ng/ml, respectively, and C-reactive protein levels were normal in 20% of cases. The most frequently isolated microorganisms were Escherichia coli (56%) and Klebsiella pneumoniae (16%). The extended-spectrum beta-lactamase rate was 35% for E. coli and 43% for K. pneumoniae isolates. Fosfomycin and ertapenem were the most effective antibiotics.Conclusion: Procalcitonin levels were high; however, the fact that C-reactive protein was found to be normal in one-fifth of cases should serve as a warning that urinary system infection can be missed in elderly patients in cases in which only C-reactive protein level is evaluated.