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Type of test | Performed in | Time required | Merits | Demerits |
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Observing gross lesions | Dead birds | 1 hour | Easy diagnosis | Only presumptive diagnosis |
Acid fast staining | Dead birds | 1 hour | Easy definitive diagnosis | Less sensitive, Not able to distinguish amongst species |
Isolation/Culture | Dead birds | About 4 weeks | Definitive diagnosis | Time consuming |
Tuberculin test | Live birds | 48 hours | Easy to perform Definitive diagnosis | Time consuming, Test is not very sensitive, Possibility of false positive and false negative results |
Agglutination test | Live birds | Few minutes | Can differentiate serotypes. Useful for screening large flocks for immediate culling | Occasionally false positive reactionsNot reliable in caged birds |
ELISA | Live birds | 2 hours | Definitive diagnosis Can be used for exotic and pet birds | Less specific than tuberculin test False positives may be there |
DNA probes | Bacterial cultures | 4–6 hours | Highly sensitive and specific | Probe may react with isolates that genetically or biochemically do not fit within the MAC |
PCR | Dead/live birds/cultures | 4 hours | Highly sensitive and specific | Requires specialized laboratory and trained personnel |
RFLP | Bacterial cultures, clinical samples | 1 day | Differentiates mycobacteria to the species level Discriminative for the analysis of strain relatedness | Insufficient quantities of gene makes visualization of digested fragments difficult |
Multiplex PCR | Bacterial cultures/clinical samples | 5–8 hrs | Rapid and inexpensive technique for subspecies identification and differential diagnosis of the MAC complex | Requires specialized laboratory |
Sequencing of the 16S rRNA gene | Bacterial cultures | 2 days | Powerful technique for differentiating species | Labor-intensive and difficult to implement in routine diagnosis |
HPLC | Bacterial cultures | 1 day | Can identify Mycobacteriumisolates to the species level | Uses costly equipment and requires substantial amounts of the test organism. |
Real-Time PCR | Bacterial cultures/clinical samples | 4–6 h | Low risk of sample contaminationOffers the possibility to quantify bacterial load | Sensitivity could be affected by the initial volume of DNA present |
MIRU-VNTR/MATR-VNTR typing | Bacterial cultures/clinical samples | 1 day | Improves RFLP discrimination Useful for determination of genotypic diversity of M. avium subspecies | Requires specialized laboratory |
Pathogenicity tests | Live young birds | 5–6 weeks | Likelihood of the etiological agent can be knownUseful in cases where the typing facilities are not available | Time consuming and concerned to ethical issues |
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