Pasteurella multocida bacterial meningitis caused by contact with pigs

Localization of Pasteurella multocida antigens in the brains of pigs naturally infected with Pasteurellosis revealing a newer aspect of pathogenesis

Pasteurella multocida is an economically important respiratory pathogen of pigs confronting swine industry worldwide. Despite extensive research over the decades, its pathogenesis is still poorly understood. Recent reports have demonstrated the nervous system affection as a newer aspect of pathogenesis by Pasteurella multocida type B:2 in Haemorrhagic Septicemia, but there are no reports of the involvement of nervous system by P. multocida in pigs. Therefore, the study was aimed to explore the neurovirulence of Pasteurella multocida in naturally infected pigs. A total of 15 brains were collected from the natural cases of pig mortality suggestive of Pasteurellosis. Grossly, the leptomeninges were markedly congested and brains were oedematously swollen. Histologically, there was moderate to severe fibrinohaemorrhagic and mononuclear cells exudates present in the leptomeningeal tissue and cerebrospinal spaces. Similar vascular inflammatory lesions (perivascular and perineuronal) along with gliosis, neuronal degeneration and necrosis were noted in various subanatomical sites of the brain (cerebrum, cerebellum, brainstem and spinal cord). The culture and biochemical tests showed the presence of P. multocida within the brain tissue. P. multocida type specific antibody staining in the brain tissues revealed intense distribution of antigens in the inflammatory exudates of meningeal vessels, neurons, glial cells and endothelial cells of the blood vessels contributing its association with neuropathological lesions. Pasteurella multocida specific PCR amplification of capsular polysaccharide gene yielded 460 bp and multiplex PCR showed the involvement of capsular serogroups A &D. All the isolates showed the presence of 10 genes for virulence factors. The disease confirmation of both serotypes was proven by Koch's postulates using Swiss albino mice. Further, histopathological brain lesions along with the immunohistochemical detection of bacterial antigens were corroborated with natural cases of P. multocida as described above. To the best of our knowledge, we first time report the neuroinvasion of P. multocida in naturally infected pigs.

Quantification of Pasteurella multocida in experimentally infected pigs using a real-time PCR assay

The aim of the study was to quantify Pasteurella multocida in experimentally infected pigs using a new qPCR assay based on the sodA gene and validated with 35 P. multocida strains, including strains isolated from pigs with pneumonia, clinically healthy pigs (nasal cavities), and human infections. The specificity of the test was verified with a collection of 60 strains of bacterial species other than P. multocida. The estimated detection threshold was 10 genome equivalents per microliter. The amplification efficiency and value of the correlation coefficients were 95.5% (±3.5%) and 0.995 (±0.005), respectively. Analysis of P. multocida suspensions in Buffered Peptone Water Broth and of samples prepared from lungs experimentally spiked with P. multocida revealed detection thresholds of 1.4CFU/μl and 8.4CFU/μl, respectively. In live pigs, experimentally-infected, approximately 10⁵, 10⁷ and 10⁸genomeequivalents/ml of P. multocida DNA was detected on Day 8 post-infection in the nasal cavities, tonsils and trachea samples, respectively. In dead pigs, approximatively 10⁷genomeequivalents/ml of P. multocida DNA was detected in the lung tissue with pneumonia. The qPCR assay's diagnostic specificity and sensitivity were 100% and 96%, respectively. This new qPCR assay should be a very useful tool for controlling enzootic pneumonia and studying the dynamics of infections in pig herds.

Meningitis caused by Pasteurella multocida in a dog owner without a dog bite: clonal lineage identification by MALDI-TOF mass spectrometry

Background

Pasteurella multocida meningitis in an immunocompetent patient is rare and commonly occurs after animal bite. To our knowledge, only 48 cases have been reported in the literature since 1989. P. multocida meningitis is commonly linked to animal contagion. Here we report on a new case of P. multocida meningitis in an immunocompetent patient who is a dog owner without a dog bite. We used the matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry to investigate the clonal lineage between animal and human isolates.

Case presentation

In our case, a 25-year-old immunocompetent French Caucasian woman with nothing notable in her medical history was admitted for meningitis caused by P. multocida. Clonal lineage of P. multocida strains from cerebrospinal fluid and blood culture and her dog’s oral cavity has been recognized by MALDI-TOF mass spectrometry dendrograms and clustering of the 21 P. multocida isolates in our centres. She was treated by a combination of intravenous ceftriaxone (2 g/day) and oral levofloxacin (1 g/day). She was discharged on the 6th day of admission. The antimicrobial therapy was conducted for 15 days. The dog was treated by clavulanic-acid amoxicillin for 3 weeks by the veterinarian. The evolution of the patient at the 5th month after the end of the antimicrobial therapy was normal without any neurological after-effects.

Conclusion

The meningitis caused by P. multocida could be considered a cause of human meningitis in dog lovers without an animal bite. MALDI-TOF mass spectrometry should be considered as it is an accurate tool to identify clonal lineage between animal and human isolates.

An unusual case of meningitis

Pasteurella multocida is a Gram-negative anaerobe that is known to colonize household pets; in fact, it has been reported to be present in a majority of cats and dogs. P multocida can cause a variety of infections in humans, of which skin infections are the most common. This article describes a case involving a 56-year-old man who developed meningitis caused by P multocida following tympanomastoidectomy. The authors discuss the treatment course and most likely route of infection in this case, and summarize the cases of P multocida-associated meningitis presented in the literature.

Pasteurella multocida is a rare cause of bacterial meningitis. A 56-year-old man with several pets developed a profoundly decreased level of consciousness following left tympanomastoidectomy. Lumbar puncture produced cerebrospinal fluid with the typical findings of meningitis (low glucose, high protein, high leukocytes). Cultures from the cerebrospinal fluid and a swab of the left ear revealed Gram-negative coccobacillus identified as P multocida. The organism was sensitive to ceftriaxone, ampicillin and penicillin, and a 14-day course of intravenous penicillin was used as definitive treatment, resulting in full recovery. Although rare, P multocida should be considered as a potential cause of meningitis in patients with animal exposure, particularly in the setting of recent cranial surgery.