Factors affecting the increase of R plasmids during hospitalization

The incidence of the TEM -lactamases among 3,010 Gram-negative rods isolated from 670 anorectal swabs was determined by immunological tests. The results from 44 persons without hospital contact were compared with results from 242 hospitalized patients and 30 nurses working in the hospital. The TEM -lactamase has been found in 10% of the strains isolated from the control group and from patients on day 0 and in 20% of the strains isolated from nurses. On day 10, the number of TEM strains had risen to 15% in hospitalized patients but remained stable in the control group. The increase of TEM-producing strains is significantly favored in patients receiving antimicrobial agents, but also occurred in patients without antibiotic therapy. Patients in surgery acquired TEM-producing strain as much as patients in internal medicine. Older patients (35 years) acquired more TEM-producing strains even if they did not receive antibiotics. The factors influencing the prevalence of TEM-type -lactamase were the duration of hospitalization and the age of the patient.