[Varying sensitivity of Gram-negative bacteria in the urine to nitrofurantoin itself, to combined nitrofurantoin-sulphadiazine and combined sulphonamide-trimethoprim (author's transl)].

In connexion with the compound produce, nitrofurantoin sulphadiazine (ratio 1:3), it was questioned whether the relative disc (ratio 1:1, produced by BBL-USA on the findings of Tiesler, 1969), should be incorporated in the routine testing of urinary bacteria in addition to the testing of pure nitrofurantoin. Since pure sulphonamide is not in our routine test programme the sulphonamide-trimethoprim combination was also included in the study at a later time on the basis of initial results. Statistical analysis showed the overall superiority of the combination of nitrofurantoin with sulphadiazine and, moreover, a significant difference in sensitivity of E. coli in comparison with problematic gram-negative bacteria where the sensitivity values and likewise, the discordance quota were markedly higher for the compound preparation. The sulphonamide-trimethoprim combination proved even less effective and demonstrated a higher level of discordance than with pure nitrofurantoin. Annually about 45% of all examined urinary samples yield gram-negative bacteria posing therapeutic problems. Hence, the nitrofurantoin-sulphadiazine compound product (BBL-disc) was incorporated in our routine test programme.