D359 - Pasteurella spp.

Description:

Pasteurella species are small, nonmotile, gram-negative, bi-polar-staining bacilli that are clinically significant in many dog and cat bite wounds. These organisms normally inhabit the nasal, gingival, and tonsillar regions of approximately 12% to 92% and 52% to 99% of dogs and cats, respectively, as well as many other animals. Pasteurella species are isolated in up to 45% of transtracheal washings from dogs with pneumonia. Concurrent viral infections and other stresses to the host lead to proliferation and subsequent migration of Pasteurella to lower airways. Reduced defence mechanisms lead to impaired bacterial clearance from the lung with resultant pneumonia. Pasteurella secretes a gram-negative endotoxin that decreases the quantity, and increases the surface tension, of pulmonary surfactant thereby altering pulmonary mechanics and gas exchange. Once pneumonia develops, it may be slow to resolve and abscesses or pleuritis may develop.
Pasteurella multocida is the most common respiratory pathogen in the domestic rabbit. There are many manifestations of P. multocida infection including rhinitis, conjunctivitis, pneumonia, abscesses, genital tract infections, and septicemia. P. multocida transmission occurs by aerosolization or contact, either directly or through fomites, with an infected rabbit. P. multocida initially colonizes the pharynx, then moves to the nasal cavity and surrounding tissue, with possible spread to the rest of the body. Colonization of the nasal cavity may take two weeks to occur, at which time clinical signs may or may not appear. Once rabbits are infected, they may carry P. multocida for an indefinite time without exhibiting clinical signs.

Diagnosis:

Conventionally, diagnosis of Pasteurella was based on clinical findings, culture and/ or serological testing. Although culture methods are definitive, they require special facilities and the procedures can be time consuming and sometimes costly. Also, false-negative culture results are regularly observed if P. multocida dies during transport to the laboratory or are overgrown by other bacteria (nasal flora and contaminants) in the culture. Serology can be used for cases when infection is suspected in organs for which cultures are not attainable, or when culturing has yielded no results. The presence of a positive titer to P. multocida indicates either infection with or exposure to the organism. Because many rabbits and other animals routinely harbour this organism, a diagnosis of pasteurellosis cannot be made based on serologic results alone. Fortunately, new generation, DNA-based diagnostic tests circumvent most of the problems associated with conventional diagnostic methods. PCR-based testing allows the detection of specific genetic sequences unique to Pasteurella spp. therefore contamination from other organisms in samples is not a problem. This test offers veterinarians a sensitive, accurate and timely method for detecting Pasteurella and confirming infection.

Sample:

1. Whole blood (3 ml) in a lavender (EDTA) top tube.
2. Nasal swabs.

Special Handling:

Store samples at 4°C until pick up or shipment.

Test Code:

D359