Assessment of litter prevalence of Mycoplasma hyopneumoniae in preweaned piglets utilizing an antemortem tracheobronchial mucus collection technique and a real-time polymerase chain reaction assay

Abstract

The swine industry currently lacks validated antemortem methods of detecting baseline herd prevalence of Mycoplasma hyopneumoniae. The focus of our study was to evaluate alternative antemortem detection techniques and to determine baseline litter prevalence in preweaned pig populations utilizing the selected technique and a real-time polymerase chain reaction (qPCR) assay. Preliminary data was analyzed on weaned piglets with evidence of respiratory disease (n = 32). Five sample types (antemortem nasal swab, tracheobronchial mucus, postmortem deep airway swab, bronchoalveolar lavage, and lung tissue) were collected from each pig. Individual samples were tested for M. hyopneumoniae using qPCR. Compared to nasal swabs, tracheobronchial mucus demonstrated higher test sensitivity (P < 0.0001). Tracheobronchial mucus was collected from apparently healthy preweaned piglets (n = 1,759; sow farms 1-3) and preweaned piglets exhibiting signs of respiratory disease (n = 32; sow farm 4), ranging in age from 12 to 25 days. Samples from sow farms 1-3 were pooled into 2 groups of 5 per litter (n = 360 pools from 180 litters), and qPCR was utilized to analyze each pool. A qPCR-positive result, threshold cycle <37, from either pool designated the litter positive for M. hyopneumoniae. Two out of 180 litters revealed a positive result (1.1%). Individual qPCR assays were run on the samples collected from sow farm 4. Five out of 30 samples revealed a positive result (16.7%). Tracheobronchial mucus collection in combination with qPCR is a sensitive antemortem sampling technique that can be used to estimate the prevalence of M. hyopneumoniae in preweaned pigs, thus providing insight into the infection dynamics across the entire farrow-to-finish process.

Use of trachea-bronchial swab qPCR testing to confirm Mycoplasma hyopneumoniae seropositivity in an SPF breeding herd

“…Tracheo-bronchial sampling was performed as previously described [ 6 , 7 ]. Briefly, TBS samples were obtained following restraint of the piglets with a nose snare, and subsequent use of a mouth opener.…”

“…Piglets can become infected with M. hyopneumoniae during the suckling period and many studies have shown M. hyopneumoniae -positive animals from weaning onwards [ 2 – 7 ]. Moreover, once infected with M. hyopneumoniae , animals can excrete the pathogen over a long period of time, with total clearance lasting till 254 days post-infection [ 8 ].…”

“…A recent comparative study on diagnostic sampling approach for M. hyopneumoniae detection showed that laryngeal swabs were a reliable option to establish early detection of M. hyopneumoniae , followed by brocho-alveolar lavage fluids and nasal swabs [ 18 ]. Other innovative sampling techniques, such as tracheo-bronchial swab (TBS) sampling [ 6 , 7 , 19 ] have been introduced in combination with PCR detection of M. hyopneumoniae to reliably detect the pathogen of infected animals. The objective of the current case report is to show that TBS sampling is a suitable method to confirm a suspect M. hyopneumoniae -seropositive situation.…”

Development and evaluation of an indirect ELISA for the detection of Mycoplasma hyopneumoniae natural infection but not inactivated bacterin vaccination

“…It is hard to carry out retrospective experiments when the nasal swabs are stored for a long time. Furthermore, nasal swab sample collection is inconvenient in live pigs for their curved nasal cavities, and swabs were found to be not reliable at individual pig level [14][15][16].…”

Development and evaluation of an indirect ELISA for the detection of Mycoplasma hyopneumoniae natural infection but not inactivated bacterin vaccination

“…It is hard to carry out retrospective experiments. Furthermore, nasal swab sample collection is inconvenient in live pigs for their curved nasal cavities, and swabs were found to be not reliable at individual pig level[14][15][16]. Therefore, development of an IgG-ELISA method which can differentiate convalescent and hyperimmune sera is easy to get serum samples…”