Table 3.
Practices related to antibiotic susceptibility testing (AST) in the 25 laboratories that provide the test.
| Parameters | Proportion of laboratories (N = 25) | |
|---|---|---|
| n | % | |
| Average monthly number of samples tested for antibiotic susceptibility | ||
| ≤10 | 6 | 24 |
| 11–20 | 6 | 24 |
| >20 | 13 | 52 |
| AST method available | ||
| Antibiotic disc diffusion | 22 | 88 |
| E-test | 3 | 12 |
| Agar medium used for AST | ||
| Muller Hinton | 24 | 96 |
| Cled | 1 | 4 |
| Eosin Methylene Blue | 1 | 4 |
| Thickness of the medium in the petri dish | ||
| 4 mm | 23 | 92 |
| >4 mm | 2 | 8 |
| Procedure for determining inoculum | ||
| By eye without a standard | 21 | 84 |
| By eye using Mc Farland standard | 4 | 16 |
| Inoculum spreading techniques | ||
| Swabbing | 18 | 72 |
| Flooding | 10 | 40 |
| Automated Biomerieux VITEK® Compact system | 3 | 12 |
| Criteria for selecting the antibiotics | ||
| CA-SFM/EUCAST | 18 | 72 |
| Depends on the bacterium to be tested | 16 | 64 |
| Depends on availability of antibiotic discs in laboratory | 9 | 36 |
| Depends on availability of antibiotics in pharmacy | 1 | 4 |
| CLSI | 1 | 4 |
| Number of antibiotic discs tested per strain | ||
| ≤10 | 7 | 28 |
| 11–20 | 17 | 68 |
| >20 | 1 | 4 |
| Procedure for depositing antibiotic discs on agar plates | ||
| Sterile forceps | 23 | 92 |
| Antibiotic disc dispenser | 7 | 27 |
| Time from depositing of antibiotic discs to placing the agar plates into incubator | ||
| 20 min | 12 | 48 |
| 10 min | 11 | 44 |
| 1 h | 1 | 4 |
| 0 | 1 | 4 |
| Incubation time of the agar plates | ||
| 18–24 h | 25 | 100 |
| Tools used for measuring the diameters of the inhibition zones | ||
| Ruler | 18 | 72 |
| Vernier caliper | 5 | 20 |
| Ruler and caliper | 2 | 8 |
| Standards for interpretation of the AST results | ||
| CA-SFM/EUCAST | 15 | 60 |
| CA-SFM/EUCAST and the disc manufacturer's instructions | 5 | 20 |
| Disc manufacturer's instructions | 5 | 20 |
| Storage temperature of the antibiotic discs | ||
| Refrigerator | 24 | 96 |
| Ambient room temperature | 3 | 12 |
| Freezer | 1 | 4 |
| Carrying out quality control of antibiotic discs | ||
| Yes | 18 | 72 |
| Procedure for the disc quality control | ||
| Use of a reference bacterial strain | 13 | 52 |
| Use of bacterial reference strain and determination of MIC | 3 | 12 |
| Determination of MIC | 2 | 8 |
| Reasons for not performing quality control | ||
| Lack of materials | 3 | 12 |
| No reference strains | 2 | 8 |
| Lack of know-how | 2 | 8 |
| Skills improvement needed | ||
| Yes | 17 | 68 |
| No | 8 | 32 |
CA-SFM, Comité d'Antibiogramme de la Société Française de Microbiologie; EUCAST, European Committee on antimicrobial susceptibility testing; CLSI, clinical and laboratory standards institute; MIC, minimum inhibitory concentration.