Types of zones of inhibition determined by KBDA method. With FOX discs in the center, CTX discs are placed 15 mm to the left of FOX, while CAZ discs are 15 mm to the right of FOX as shown in fig 1a. (a) Susceptible zone: no growth between FOX and CTX/CAZ, E. cloacae 02212. (b) Sl zone: slight growth between FOX and CTX/CAZ, E. agglomerans 02039. (c) C zone: CTX zone distortion near FOX, S. marcescens 02319. (d) C zone: CTX zone distortion near FOX. M. morganii 02325. (e) D zone: CTX and CAZ zone truncation near FOX, E. aerogenes 02324. (f) Resistant zone: no zone of inhibition around any disc, E. cloacae strain A.