Appropriate phenotypic susceptibilities for antimicrobial susceptibility testing of Acid Fast Bacilli
Test Code
PHENO
Description
This is the orderable for appropriate phenotypic susceptibility testing only. Selection of this orderable triggers the appropriate phenotypic testing for each type of organism (Table 1), but genotypic drug resistance testing is not performed, even if appropriate. Since genotypic resistance testing can provide a fast turnaround time and important information about treatment and is only performed when relevant, PHENO is typically not the recommended test. Note that testing is not performed, reported, or billed if it is not appropriate for the organism.
PHENO can be ordered on clinical specimens sent for culture. If an organism is grown, the appropriate drugs are automatically added; testing will not be performed if no organism is cultured. PHENO may also be ordered on isolates. Note that if a customized selection of antibiotics are needed, they can be selected individually. See "Menu of Individual Drug Testing for Acid Fast Bacilli" for the full selection of antibiotics that can be ordered.
Table 1. Phenotypic and genotypic susceptibilities performed based on the organism type when APPRO is ordered.
| Organism | Phenotypic testing | |
| Billing code | Drugs | |
| M. avium complex | NTM13 | AMK, CIP, CLO, CLR, DOX, LZD, MIN, MXF, RFB, RIF, STR, TMP/SXT |
| Slowly growing mycobacteria other than M. avium complex and fastidious mycobacteria | NTM13 | AMK, CIP, CLO, CLR, DOX, LZD, MIN, MXF, RFB, RIF, STR, TMP/SXT |
| Fastidious slowly growing mycobacteria such as M. haemophilum and M. shimoidei. | BMX12 | CIP, RFB, STR, AMK, CLR, MXF, CLO, LZD, RIF, EMB |
| M. tuberculosis complex (First line drugs) | MTB2 | INH, PZA, RIF, EMB |
| Drug resistant M. tuberculosis complex (Second line drugs) | MTB1 | AMK, CAP, CS, EMB, ETH, INH, KAN, PAS, RIF, STR |
| M. abscessus and M. chelonae | NTM6, NTM6V (vet) | AMK, AUG, AXO, AZM, CIP, CLF, CLR, DOX, FEP, FOT, FOX, GEN, IPM, KAN, LZD, MIN, MXF, TGC, TOB, TMP/SXT |
| Other rapidly growing mycobacteria (e.g. M. fortuitum, M. peregrinum) | NTM6 | AMK, AUG, AXO, AZM, CIP, CLF, CLR, DOX, FEP, FOT, FOX, GEN, IPM, KAN, LZD, MIN, MXF, TGC, TOB, TMP/SXT |
| Partial acid fast bacteria (e.g. Nocardia sp., Gordonia sp., Tskuamurella sp.) | NTM4, NTM4V (vet) |
AMK, AUG, AXO, AZM, CIP, CLF, CLR, DOX, FEP, FOT, FOX, GEN, IPM, KAN, LZD, MIN, MXF, TGC, TOB, TMP/SXT |
Table 2. Drug abbreviations (used on the requisition)
| Abbreviation | Drug | Abbreviation cont'd | Drug cont'd |
| AMK | Amikacin | INH | Isoniazid |
| AUG | Augmentin | IPM | Imipenem |
| AXO | Ceftriaxone | KAN | Kanamycin |
| AZM | Azithromycin | LZD | Linezolid |
| CIP | Ciprofloxacin | MIN | Minocycline |
| CLO | Clofazimine | MXF | Moxifloxacin |
| CLO/AMK | Clofazimine & Amikacin synergy | OMC | Omadacycline |
| CLR | Clarithromycin | PAS | p- Aminosalicyclic acid |
| CAP | Capreomycin | PZA | Pyrazinamide |
| CS | Cycloserine | RFB | Rifabutin |
| DOX | Doxycycline | RIF | Rifampin |
| EMB | Ethambutol | RIF/EMB | Rifampin & Ethambutol synergy |
| ETH | Ethionamide | STR | Streptomycin |
| FEP | Cefepime | TGC | Tigecycline |
| FOT | Cefotaxime | TMP/SXT | Trimethoprim/sulfamethoxazole |
| FOX | Cefoxitin | TOB | Tobramycin |
| GEN | Gentamicin |
Collect
An identified isolate is required for testing (does not necessarily apply to veterinary rapidly growing isolates).
- This test can be ordered on a clinical specimen that has been sent to our laboratory for isolation and identification of mycobacteria. See specimen requirements for culture of mycobacteria from a clinical specimen (AFB1, AFB3 or AFB7)
- This test can also be ordered on organisms identified elsewhere. Pure mycobacterial isolates should be sent in solid media such as a Middlebrook slant (7H10 or 7H11), Lowenstein-Jensen (LJ) slant, or in broth (7H9, MGIT, MP BACT/Alert, VersaTrek).
- Specimen Volume: Laboratory must receive visible growth of an isolate on solid media or an isolate in broth media (≥3 mL).
Unacceptable Conditions
- Cultures received with incomplete identifiers.
- Mixed cultures; Note that prior to rejection, attempts will be made to isolate organisms. A re-isolation charge will be applied in these cases.
- Cultures containing mold.
- Solid media with insufficient growth.
- Cultures submitted on agar plates.
- Liquid media with < 2 mL.
- Leaking specimens.
Storage Transport Temp
Transport or mail isolates at ambient temperature. For nontuberculous mycobacteria (NTM), follow IATA/ DOT category B and for M. tuberculosis complex isolates, follow IATA/DOT category A requirements for shipping biological materials.
Performed
Typically all days
Methodology
Phenotypic susceptibilities are performed using agar proportion, broth microdilution, or broth macrodilution methods.
Reported
- MIC's for M. tuberculosis complex and other slowly growing mycobacteria are reported 4 to 6 weeks after a pure culture is achieved.
- MIC's for rapidly growing mycobacteria and aerobic actinomycetes are reported 2 to 3 weeks after a pure culture is achieved.
Department
Infectious Disease Laboratory, MycobacteriologySynonyms
BMX12, NTM13, AFB6, MTB1, MTB2, NTM4, NTM4V, NTM6, NTM6V
Interpretation
Susceptible, intermediate, or resistant (S, I, R) interpretations will be included whenever CLSI interpretations are available for a drug-organism combination.
CPT Code
| Test code performed within APPRO | CPT Code | Billing Code |
| BMX12 | 87181 x2 and 87188 x7 | BMX12 |
| MTB1 | 87190 x10 | MTBP1 |
| MTB2 | 87188 x5 | MTBP2 |
| NTM4 | 87186 | NTMP4 |
| NTM4V | 87186 | NTP4V |
| NTM6 | 87186 | NTMP6 |
| NTM6V | 87186 | NTMPV |
| NTM13 | 87186 | NTM13 |