[Use of aminopenicillins: first cause of error in the prescription of antimicrobial agents at a hospital].

The patterns of use and quality of prescription of ampicillin and amoxycillin (A/A) as compared with the rest of antimicrobials (AM) was evaluated by means of the review of the therapeutic sheets of 4572 admitted patients, in coincidence with 5 calculations of prevalence in a university hospital. 25.7% of patients received AM. These were used in 865 instances, and 6% were disqualified. A/A participated in 57% of these errors (p = 0.002 as related with the rest of AM). 309 patients received AM as prophylactic drugs, and 70% of them did not comply with the standard rules. The election of A/A for prophylaxis was associated with 71% of these errors (p less than 0.0001). Nine out of every 10 prophylactic administrations of A/A were abnormal owing to incorrect indication (77%), dosage (10%), oral route (62%) or excessive duration (82%). The high prevalence of prescription of aminopenicillins (30%) was associated with 68% of the errors in the use of AM, owing, among other reasons, to the high resistance rates of the major recovered organisms excluding enterococci. The nonjustified overuse of aminopenicillins was the leading detected problem; it can be managed by a restrictive antibiotic policy and educational measures oriented to an adequate medical prescription.