Spreading of Pasteurella multocida Infection in a Pet Rabbit Breeding and Possible Implications on Healed Bunnies

Abstract

The number of pets such as dogs, cats, rabbits, and parrots has increased in European families. Social benefits to owners such as decreasing feelings of loneliness and anxiety are provided by pets which are also used in Animal-assisted Therapy (AAT). Nevertheless, human-animal interactions are also associated with health problems including allergies, asthma, and zoonosis. Rabbits may carry potential pathogens for humans. One of the most common bacteria that colonizes the oro-pharynx and the upper respiratory tract of rabbits is Pasteurella (P.) multocida. Transmission of the infection to humans results from scratches, licks, and bites but it also can occur from the inhalation of air particles containing the microorganism. Immunocompromised people or persons with pulmonary disorders are particularly susceptible to the infection. Infected rabbits may carry P. multocida with or without clinical signs. In this paper, the sensitivity to antibiotics and the invasiveness ability of P. multocida identified in a farm of pet rabbits affected by severe pasteurellosis were investigated. The strain was P. multocida belonging to capsular type A which is the type most often detected in humans. The identified strain was susceptible to the tested antibiotics, but it appeared equipped with several virulence genes which are responsible for fimbriae production, adhesion processes to host cells, enzyme production, and are involved in iron acquisition processes. These findings are of particular interest because rabbits recovered from pasteurellosis very often become carriers of the bacteria. Therefore, we suggest considering P. multocida screening in the routine medical checks of rabbits, especially if they are meant to be companion animals for children and elder people, given that the transmission of the pathogen cannot be excluded.

Keywords: Pasteurella multocida; pet rabbit; vaccine; virulence genes.

Figure 1

Left side of a bunny with severe clinical signs. Note the swollen eyelids and the purulent discharge on the hair around the nostrils.

Figure 2

Left side of the head of a bunny with severe conjunctivitis. Note the purulent ocular discharge that occludes the eyelid.

Figure 3

Bunny with severe purulent rhinitis.

Figure 4

Microbiological findings from conjunctival sample: colonies were grown on blood agar and were identified as Pasteurella multocida.

Figure 5

Identification of P. multocida type A by PCR: M: Marker (O’ Gene Ruler 1kb DNA Ladder, Ready to use, 250–10,000 bp, Thermo Scientific Inc.). Lanes 1, 2, 3, 4: conjunctival samples; Lanes 5, 6, 7: nasal samples; M: Marker; Lane 8: P. multocida type A positive control; Lane 9: P. multocida type F positive control; and Lane 10: negative control.

Figure 6

Detection of virulence genes of P. multocida by PCR. Protocol A: detection of SodA (361 bp), Fim4 (488 bp): Lanes 1, 2: conjunctival samples; Lanes 3, 4: nasal samples; Lane 5: positive control; Lane 6: negative control; M: Marker: O’ Gene Ruler 1kb DNA Ladder, Ready to use, 250–10,000 bp, Thermo Scientific Inc. Protocol B: detection of SodC (235 bp), TadD (416 bp), nanB1 (544 bp), HgbB (788 bp), ExbB (1144 bp): Lanes 7, 8: conjunctival samples; Lanes 9, 10: nasal samples; Lane 11: positive control; Lane 12: negative control; M: Marker. Protocol C: detection of Fur (244 bp), NanH1 (360 bp), FimA (866 bp), Oma87 (948 bp): Lanes 13, 14: conjunctival samples; Lanes 15, 16: nasal samples; Lane 17: positive control; and Lane 18: negative control.