[Antibiotic therapy in the elderly: features and problems]

Bacterial infections cause 30% of deaths in the elderly and are the most frequent cause of hospitalization in elderly patients. Diagnosis of infection can be difficult because aged patients may have neither fever nor leucocytosis; most patients present unusual symptoms such as changes in mental status. The clinician must be cognizant of the frequent noncompliance with drug regimens because lack of elderly adherence to a prescribed antibiotic therapy has the potential to result in treatment failure and to foster the emergence of drug-resistant bacteria. Elderly frequently are taking other drugs such as antiarrhythmics and antihypertensives; ignorance of potential antibiotic-drug interaction can result in ineffective treatment or enhanced toxicity. Aging is associated with changes in physiological processes; the age-related decline in renal function influences the excretion of some antibiotics (aminoglycosides, vancomycin, ofloxacin). The increased potential for toxicity of antimicrobial agents requires a careful drug selection as well as clinical and laboratory monitoring. The most frequent infections occurring in the elderly are pneumonia, urinary tract infection, intra-abdominal infection and soft tissue infection; prevalence and incidence of bacterial meningitis, bacterial endocarditis and bacteraemia are increasing with a mortality rate of 20 to 40%. These bacterial infections have different microbial causes and require different therapeutic approaches according to sites involved, elderly's salient features and overall susceptibility of the bacteria in the ecosystem. Appropriate empirical antibiotic treatment reduces mortality also in bacteraemic old patients.