Pet Pyometra: Correlating Bacteria Pathogenicity to Endometrial Histological Changes

Abstract

Pyometra is a life-threatening infectious disease that frequently affects bitches and queens. Although histopathological patterns of pyometra have been extensively explored, the microbiological aspects, such as bacteria pathogenicity, have not been correlated to microscopy endometrial lesions so far. In this study, these two pathological aspects of pyometra were analysed and correlated. Uterus fragments and intrauterine content samples were collected from pets diagnosed with pyometra (30) and submitted to histopathology analysis and bacterial culture, respectively. The degree of endometrial histopathological lesions in pyometra cases were classified as mild, moderate and severe. Thirty different bacteria isolates were identified from intrauterine content culture. Escherichia coli (E. coli) was pure isolated in 57.7% and highly related to severe endometrial lesions. Immunohistochemistry assay revealed the adhesion and invasion of this bacteria agent to the injured endometrium. Virulence aspects of these E. coli strains were explored, demonstrating biofilm formation ability and a set of virulence genes in most isolates. These results support the adaptive genetic and phenotypic advantages of E. coli for uterus infection, and justify the high frequency of this agent involved in pyometra cases.

Characterization of Escherichia coli in Dogs with Pyometra and the Influence of Diet on the Intestinal Colonization of Extraintestinal Pathogenic E. coli (ExPEC)

“…In the present study, phylogroup B2 was the most frequent in the uterine contents of bitches, with clinical cases of pyometra caused by E. coli ( Figure 1 ), corresponding to 85% of the isolates. This frequency is similar to that found in previous studies on pyometra, suggesting a high capacity of phylogroup B2 strains to colonize the canine uterus [ 7 , 11 , 31 ].…”

“…Although the pathogenesis of pyometra is poorly understood, previous studies have suggested that the intestine is the main source of E. coli strains that ascend into the uterus [ 1 , 2 , 7 ]. This study reinforces this hypothesis, as bitches with E. coli pyometra were more likely to harbor E. coli strains from phylogroup B2 in the rectal swab when compared to the group of bitches without E. coli pyometra.…”

“…Extraintestinal pathogenic Escherichia coli (ExPEC) is the most common pathogen involved in canine pyometra and has been reported in 57–100% of cases [ 1 , 2 , 6 , 7 ]. These isolates are phylogenetically and epidemiologically distinct from E. coli strains commonly found in intestinal commensals that cause diarrhea and other gastrointestinal disorders [ 8 , 9 , 10 ].…”

“…In contrast, commensal intestinal strains of E. coli in dogs are mostly classified into phylogenetic groups B1 and A [ 5 , 9 , 12 ]. In addition, E. coli recovered from pyometra have specific virulence factors, such as adhesins, toxins, iron acquisition systems, and protectins [ 7 , 14 , 15 ], which are commonly classified as endometrial pathogenic E. coli (EnPEC), a subgroup of the ExPEC pathotype. These virulence factors may confer a selective advantage over commensal strains [ 16 ], playing a key role in the development of canine pyometra [ 11 , 14 , 17 ] as well as in other extraintestinal infections in humans and animals [ 16 , 17 , 18 ].…”

“…Although the intestinal ascension of E. coli strains is currently the most accepted hypothesis in the pathogenesis of canine pyometra [ 1 , 2 , 7 ], no studies have evaluated the influence of the dog diet on the specific colonization of ExPEC strains. In the last decade, an increasing number of owners have been feeding their dogs and cats raw meat-based diets (RMBDs), instead of regular commercial dry feed [ 19 ].…”