Bacteriemia por Pasteurella multocida asociada al contacto con un animal doméstico / Pasteurella multocida bacteremia associated with contact with a domestic animal: case report

Resumen Pasteurella multocida es reconocida por ser una de las especies más frecuentemente aisladas en la microbiota oral de animales domésticos y salvajes; asociadas a infecciones de piel y tejidos blandos secundarias a mordeduras y rasguños. Las infecciones sistémicas son poco frecuentes, asociadas a la diseminación desde infecciones localizadas y a factores de riesgo asociados a inmunosupresión. Presentamos un caso de bacteriemia por Pasteurella multocida en un paciente de 88 años, relacionada con alimentos compartidos con su mascota; un mecanismo de producción de bacteriemia nunca antes descrito en la literatura médica.

Pasteurella species are known to be one of the most frequently isolated in oral microbiota of domestic and wild animals, because of that, they are associated with skin and soft tissues infections secondary to bites and scratches. Systemic infections are uncommon, but are associated with dissemination from localized infections and some risks factors related to immunosuppression. We report a case of Pasteurella multocida bacteremia in an 88 years old patient, associated with food sharing with his dog; a bacteremia mechanism never described before in the medical literature.

Variation in the molecular weight of Photobacterium damselae subsp. piscicida antigens when cultured under different conditions in vitro

The antigenicity of Photobacterium damselae (Ph. d.)subsp. piscicida, cultured in four different growth media[tryptone soya broth (TSB), glucose-rich medium (GRM),iron-depleted TSB (TSB+IR-), and iron-depleted GRM(GRM+IR-)] was compared by enzyme-linked immuno-sorbent assay (ELISA) and Western blot analysis usingsera obtained from sea bass (Dicentrarchus labrax) raisedagainst live or heat-killed Ph. d. subsp. piscicida. Theantigenic expression of Ph. d. subsp. piscicida was found todiffer depending on the culture medium used. A significantlyhigher antibody response was obtained with iron-depletedbacteria by ELISA compared with non-iron depletedbacteria obtained from the sera of sea bass raised againstlive Ph. d. subsp. piscicida. The sera from sea bass raisedagainst live bacteria showed a band at 22kDa in bacteriacultured in TSB+IR- or GRM+IR- when bacteria thathad been freshly isolated from fish were used for thescreening, while bands at 24 and 47kDa were observedwith bacteria cultured in TSB or GRM. When bacteriawere passaged several times on tryptic soya agar prior toculturing in the four different media, only bands at 24 and47kDa were recognized, regardless of the medium used toculture the bacteria. It would appear that the molecularweight of Ph. d. subsp. piscicida antigens change in thepresence of iron restriction, and sera from sea bassinfected with live bacteria are able to detect epitopes onthe antigens after this shift in molecular weight.

Immunologic reactivity of a lipopolysaccharide-protein complex of type A Pasteurella multocida in mice

The immunologic reactivity of a lipopolysaccharide (LPS)-protein complex isolated from a potassium thiocyanate extract of a Pasteurella multocida (capsular type A and somatic type 3) strain was evaluated in mice. The LPS-protein complex provided 100% protection in mice against a challenge with the homologous strain. However, when the complex was fractionated into LPS and protein moieties by phenol-water treatment, both components lacked immunogenicity. The complex and extracted components were mitogenic for mouse B lymphocytes with the protein moiety the most active. Although immune serum against the LPS-protein complex protected mice against challenge thereby indicating a role for humoral immunity, the LPS-protein complex of P. multocida was also found to induce cell-mediated immunity. This cell-mediated immunity was demonstrated in mice immunized with the complex by: (1). mitogenic responses of T lymphocytes, (2). induction of delayed type hypersensitivity reaction in the hind footpads, and (3). enhanced resistance to challenge infection with Salmonella enteritidis.