Effectiveness and Appearance of Resistant Faecal E. coli Flora during Preventive Treatment in Winter with Azidocillin and Ampicillin

The clinical effect of continuous prophylaxis in winter with a new penicillin, azidocillin, was compared with that of ampicillin and placebo in children with recurrent respiratory infections. The patients were subject to recurrent infection because of either constitutional susceptibility or because of cardiac malformation with left-right shunt. Azidocillin and ampicillin were equally effective. Compared with placebo, a difference in favour of both antibiotics was indicated in the children with ‘constitutional’ respiratory disease. The influence of the treatment on the faecal E. coli flora was also studied. Both azidocillin and ampicillin caused an increase in ampicillin-resistant E. coli strains. This finding is unexpected because E. coli shows a primary resistance to azidocillin. A possible explanation is discussed.