Affects: Cats, Dogs
Pasteurella multocida is a Gram-negative, nonmotile, penicillin-sensitive coccobacillus from the family Pasteurellaceae. P. multocida is the cause of a range of diseases in mammals and birds, including fowl cholera in poultry, atrophic rhinitis in pigs, and bovine hemorrhagic septicemia in cattle and buffalo. It can also cause a zoonotic infection in humans, which typically is a result of bites or scratches from domestic pets. Many mammals (including domestic cats and dogs) and birds harbor it as part of their normal respiratory microbiota, rendering them silent sources of infection.
Diagnosis And Treatment: Diagnosis of the bacterium in humans was traditionally based on clinical findings, and culture and serological testing, but false negatives have been a problem due to easy death of P. multocida, and serology cannot differentiate between current infection and previous exposure. The quickest and most accurate method for confirming an active P. multocida infection is molecular detection using polymerase chain reaction.
This bacterium can be effectively treated with β-lactam antibiotics, which inhibit cell wall synthesis. It can also be treated with fluoroquinolones or tetracyclines; fluoroquinolones inhibit bacterial DNA synthesis and tetracyclines interfere with protein synthesis by binding to the bacterial 30S ribosomal subunit. Despite poor in vitro susceptibility results, macrolides (binding to the ribosome) also can be applied, certainly in the case of pulmonary complications. Due to the polymicrobial etiology of P. multocida infections, treatment requires the use of antimicrobials targeted at the elimination of both aerobic and anaerobic, Gram-negative bacteria. As a result, amoxicillin-clavulanate (a beta-lactamase inhibitor/penicillin combination) is seen as the treatment of choice.
Prevention: No vaccine is available for humans. If skin is broken by an animal bite, risks of infection can be reduced by thoroughly cleaning the wound, disinfection, and dressing. The would should not be closed (e.g. by suture) unless necessary as doing so increases the risk of infection. Prophylactic antibiotics may be considered in immunocompromised people, but is not routinely recommended otherwise.
Vaccination: Vaccines are available for livestock. The traditional inactivated vaccines tend to provide a short protective duration and only occasionally provides cross-protection. Many of the live attenuated vaccines provide cross-protection against infection of the same capsular serogroup or LPS serovar. Future subunits, peptide, and DNA vaccines can potentially confer immunity against more broadly shared parts of the bacterium such as a specific outer membrane protein or a secreted toxin.
Vaccine: Vaccination against progressive atrophic rhinitis was developed by using a recombinant derivative of P. multocida toxin. The vaccination was tested on pregnant gilts (female swine without previous litters). The piglets born to treated gilts were inoculated, while the piglets born to unvaccinated mothers developed atrophic rhinitis.