Veterinary Medicine International / 2011 / Article / Tab 2

Review Article

Tuberculosis in Birds: Insights into the Mycobacterium avium Infections

Table 2

Diagnostic methods and tests used in birds [2, 3, 5, 23, 4347].

Type of testPerformed inTime requiredMeritsDemerits

Observing gross lesionsDead birds1 hourEasy diagnosisOnly presumptive diagnosis
Acid fast stainingDead birds1 hourEasy definitive diagnosisLess sensitive, Not able to distinguish amongst species
Isolation/CultureDead birdsAbout 4 weeksDefinitive diagnosisTime consuming
Tuberculin testLive birds48 hoursEasy to perform
Definitive diagnosis
Time consuming, Test is not very sensitive, Possibility of false positive and false negative results
Agglutination testLive birdsFew minutesCan differentiate serotypes. Useful for screening large flocks for immediate cullingOccasionally false positive reactionsNot reliable in caged birds
ELISALive birds2 hoursDefinitive diagnosis
Can be used for exotic and pet birds
Less specific than tuberculin test
False positives may be there
DNA probesBacterial cultures4–6 hoursHighly sensitive and specificProbe may react with isolates that genetically or biochemically do not fit within the MAC
PCRDead/live birds/cultures4 hoursHighly sensitive and specificRequires specialized laboratory and trained personnel
RFLPBacterial cultures, clinical samples1 dayDifferentiates mycobacteria to the species level Discriminative for the analysis of strain relatednessInsufficient quantities of gene makes visualization of digested fragments difficult
Multiplex PCRBacterial cultures/clinical samples5–8 hrsRapid and inexpensive technique for subspecies identification and differential diagnosis of the MAC complexRequires specialized laboratory
Sequencing of the 16S rRNA geneBacterial cultures2 daysPowerful technique for differentiating speciesLabor-intensive and difficult to implement in routine diagnosis
HPLCBacterial cultures1 dayCan identify Mycobacteriumisolates to the species levelUses costly equipment and requires substantial amounts of the test organism.
Real-Time PCRBacterial cultures/clinical samples4–6 hLow risk of sample contaminationOffers the possibility to quantify bacterial loadSensitivity could be affected by the initial volume of DNA present
MIRU-VNTR/MATR-VNTR typingBacterial cultures/clinical samples1 dayImproves RFLP discrimination Useful for determination of genotypic diversity of M. avium subspeciesRequires specialized laboratory
Pathogenicity testsLive young birds5–6 weeksLikelihood of the etiological agent can be knownUseful in cases where the typing facilities are not availableTime consuming and concerned to ethical issues