Table 2.

Advantages and disadvantages of available diagnostic tests to detect bacterial pathogens involved in respiratory disease in live cattle

	Use	Turnaround Time∗	Advantages	Disadvantages
Microbial Culture	Live bacteria detection	•24 h to 3 d for Pasteurellaceae •>5 d for Mycoplasmata	•Cheap •Evidence of live pathogen •Quantification possible •Antibiogram possible	•Live organisms needed •More time consuming •Lower sensitivity •Fastidious growers (eg, Histophilus somni) more easily overgrown (false-negatives) •Specific media needed for certain pathogens (eg, mycoplasmata)
PCR	DNA detection (specific genomic region)	•24 h	•Very high sensitivity •No live organisms required •Limited effects of contaminated samples •Pooling of samples possible •Quantification possible (qPCR)	•Possible detection of insignificant quantities or dead bacteria (high sensitivity) •Possible detection vaccine antigen (false-positive) •More expensive
Serology (Antibody ELISA)	Antibody detection	•Variable (24 h to 1 wk) depending on laboratory routine •3 wk for paired sera	•Longer time frame for pathogen detection •Both infection as vaccination status	•Indirect evidence of infection •Variable, but generally lower sensitivity and specificity •Results require 3 wk (paired sera) •No differentiation vaccine induced antibodies from natural infections
Culture-enriched Direct MALDI-TOF	Live bacteria detection	•6 h for Pasteurellaceae •3 d for Mycoplasmata	•Cheap (cost comparable with culture) •Rapid •Antibiogram possible with MBT-ASTRA	•MALDI-TOF required •Lower diagnostic accuracy in polymicrobial or mixed culture samples
Nanosequencing	DNA detection (whole genome)	•Possible within 1–2 d	•All possible pathogens simultaneously detected and quantified •Strain typing possible	•No classic antibiogram possible •More expensive

∗ Turnaround time is the time between arrival in the laboratory and availability of the test result. Reported times are in optimal conditions.

Abbreviations: ELISA, enzyme-linked immunosorbent assay; MALDI-TOF, matrix-assisted laser desorption/ionization time of flight; MBT-ASTRA, MALDI Biotyper Antibiotic Susceptibility Test Rapid Assay; qPCR, quantitative PCR.