Table 2 Frequency of antimicrobial resistance among APEC isolates from broiler chickens by disc diffusion method
Antimicrobials (abbreviation) | Disc content (μg) | Disc diffusion interpretive criteriaa (mm) | E. coli (n =  269) | |
|---|---|---|---|---|
R | S | Number ( % )of resistant isolates | ||
β – lactams | ||||
 Amoxicillin (AX) | 25 | <14 | ≥14 | 251 (93.3%) |
 Azetronem (ATM) | 30 | ≤21 | ≥26 | 15 (5.6%) |
 Imipenem (IPM) | 10 | ≤16 | ≥22 | 0 (0%) |
β – lactamase inhibitors | ||||
 amoxicillin – clavulanic acid (AML) | 20/10 | <19 | ≥19 | 190 (70.6%) |
 Tetracyclines | ||||
 Doxycycline (DO) | 30 | ≤10 | ≥ 14 | 248 (92.2%) |
 Oxytetracyclin (OT) | 30 | ≤11 | ≥15 | 148 (55%) |
 Chlortetracycline (CHL) | 10 | ≤13 | ≥17 | 201 (74.7%) |
Sulfonamides | ||||
 Sulphamethoxazole-trimethoprim (SXT) | 23.75/1.25 | ≤11 | ≥14 | 257 (95.5%) |
Fluoroquinolones | ||||
 Enrofloxacin (ENR) | 5 | ≤15 | ≥21 | 227 (84.4%) |
 Ciprofloxacin (CIP) | 5 | ≤24 | ≥26 | 172 (63.9%) |
Aminoglycosides | ||||
 Spectinomycin (SH) | 25 | ≤11 | ≥15 | 248 (92.2%) |
 Gentamicin (CN) | 10 | ≤14 | ≥17 | 154 (57.2%) |
 Apramycin (APR) | 15 | ≤12 | ≥15 | 147 (54.6%) |
Cephalosporin | ||||
 Cephalexin (CL) | 30 | <14 | ≥14 | 236 (87.7%) |
 Ceftazidime (CZC) | 30 | ≤19 | ≥22 | 20 (7.4%) |
 Ceftriaxone (CRO) | 30 | ≤22 | ≥25 | 13 (4.8%) |
 Cefepime (FEP) | 30 | ≤24 | ≥27 | 9 (3.3%) |
Phosphoric acid derivatives | ||||
 Fosfomycin (FOS) | 50 | <24 | ≥24 | 80 (30%) |
Phenicol | ||||
 Florfenicol (FFC) | 30 | ≤10 | ≥21 | 252 (93.7%) |