Diagnostic challenges and opportunities in older adults with infectious diseases.

Infections remain a major threat to the well-being of our growing aged population. The correct and timely diagnosis of infections in older adults is increasingly important in the current age of antimicrobial resistance. Urinary tract infection, pneumonia, and bacteremia present particular challenges. In older patients with bacteremia, blood cultures have comparable yield as compared with younger patients. However, the routine triggers for ordering blood cultures may not be appropriate in older adults. In addition, resistance patterns of isolated pathogens may change with age. The main difficulties in diagnosing urinary tract infections in older adults are caused by an increased prevalence of asymptomatic bacteriuria and frequent use of urinary catheters. However, a combined noninvasive approach that includes history, physical examination, urinary dipstick testing, urine cultures, and simple blood tests can provide direction. In addition, specific guidelines for specific populations are available. In older patients suspected of bacterial pneumonia, bedside pulse oximetry and urinary antigen testing for Streptococcus pneumoniae and Legionella pneumophila provide direction for the clinician. Although infected older adults pose specific and unique diagnostic challenges, a thorough history and physical examination combined with minimally invasive testing will lead to the correct diagnosis in most older adults with infectious diseases, limiting the need for empiric antibiotics in this age group.