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Proteus mirabilis causing cellulitis in broiler chickens
Matheus Silva Sanches1, Ana Angelita Sampaio Baptista2, Marielen de Souza2
1Department of Microbiology, Laboratory of Bacteriology, Center of Biological Sciences, State University of Londrina, Rodovia Celso Garcia Cid PO-BOX 6001, Londrina, Paraná, 86051-980, Brazil.
Abstract:
Given the need to understand the virulence profile of Proteus mirabilis isolates from cellulitis in broiler chickens and their ability to cause lesions, the present study aimed to characterize genotypically and phenotypically the virulence profiles of two strains of P. mirabilis isolated from cellulitis in broilers, as well as to evaluate their ability to experimentally reproduce the lesions in vivo. The strain with the highest virulence potential (LBUEL-A33) possessed mrpA, pmfA, ucaA, atfA (fimbriae), zapA, ptA (proteases), hpmA (hemolysin), and ireA (siderophore) genes, formed a very strong biofilm, and expressed the pattern of aggregative adhesion and cytotoxicity in Vero cells. The strain with the lowest virulence potential (LBUEL-A34) did not present the pmfA and ucaA genes, but expressed the pattern of aggregative adhesion, formed a strong biofilm, and did not show cytotoxicity. Both strains developed cellulitis in an animal model within 24 h post-inoculation (PI), and the degree of lesions was not significantly altered up to 120 h PI. The LBUEL-A33 strain was also inoculated in combination with an avian pathogenic Escherichia coli (APEC 046), and the lesions showed no significant changes from the individual inoculation of these two strains. Histological analysis showed that the LBUEL-A33 strain developed characteristic cellulitis lesions. Thus, both strains of P. mirabilis isolated in our study have several virulence factors and the ability to develop cellulitis in broilers.
Insights
Proteus mirabilis strains isolated from broiler cellulitis possess virulence factors and can cause lesions. Both strains induced cellulitis in chickens within 24 hours post-inoculation.
Area of Science:
- Veterinary Microbiology
- Poultry Pathology
- Bacterial Pathogenesis
Background:
- Cellulitis is a significant concern in broiler chickens, impacting flock health and economic viability.
- Understanding the virulence factors of Proteus mirabilis is crucial for managing infections in poultry.
- Limited data exists on the specific virulence profiles of P. mirabilis strains causing cellulitis in broilers.
Purpose of the Study:
- To genetically and phenotypically characterize the virulence profiles of two P. mirabilis strains isolated from broiler cellulitis.
- To evaluate the in vivo capacity of these strains to induce cellulitis lesions in a broiler model.
- To compare the virulence of a high-virulence strain (LBUEL-A33) with a low-virulence strain (LBUEL-A34).
Main Methods:
- Genotypic analysis to identify virulence-associated genes (e.g., fimbriae, proteases, hemolysin, siderophore).
- Phenotypic characterization including biofilm formation, adhesion patterns (Vero cells), and cytotoxicity assays.
- In vivo experimental inoculation of broiler chickens to induce and assess cellulitis lesions.
- Histological examination of affected tissues.
Main Results:
- The high-virulence strain (LBUEL-A33) possessed multiple virulence genes, formed strong biofilms, exhibited aggregative adhesion, and showed cytotoxicity.
- The low-virulence strain (LBUEL-A34) lacked specific genes (pmfA, ucaA) but still formed strong biofilms and showed aggregative adhesion without cytotoxicity.
- Both P. mirabilis strains rapidly induced cellulitis lesions within 24 hours post-inoculation, with no significant changes up to 120 hours.
- Co-inoculation with avian pathogenic E. coli did not alter lesion severity compared to individual P. mirabilis inoculation.
- Histological analysis confirmed characteristic cellulitis lesions caused by the LBUEL-A33 strain.
Conclusions:
- Both P. mirabilis strains isolated from broiler cellulitis possess significant virulence factors.
- These strains are capable of experimentally inducing cellulitis in broiler chickens.
- Further research into P. mirabilis virulence mechanisms in poultry is warranted for effective disease control.
