Pyometra in Small Animals 3.0

Metagenomic and 16S rRNA analysis of culture-negative uterine samples identifies Brucella spp. in a female dog with pyometra

Canine pyometra is the most prevalent reproductive disease in female dogs and involves a complex interplay of hormonal and microbial factors. Although Enterobacteriaceae are known to be the main cause of pyometra, up to 25 % of samples remain negative when classic culture methods are used. The lack of growth in conventional media raises the intriguing possibility that non-cultivable microorganisms participate in the disease. Our study aimed to address this knowledge gap by investigating the microbiota in culture-negative uterine samples from dogs with pyometra. The purulent uterine contents of dogs with pyometra (n = 79) were subjected to bacterial culture. Most of the samples showed bacterial growth of Escherichia coli (48/79, 60.7 %) or other bacterial species (25/79, 31.8 %). Samples that tested negative using the classic culture method (6/79=7.5 %) were further analyzed using 16S rRNA gene sequencing, high-throughput 16S rRNA sequencing, and shotgun metagenomics. Only three of these provided DNA of sufficient quality for further analysis, which revealed a mixture of Haemophilus/Aggregatibacter and Fusobacterium/Porphyromonas in two uterine content. In the third sample, Brucella spp. was identified as the main genus. This study suggests that pathogens that are not easily isolated by classical culture methods, including zoonotic species, may be present in the uterus of dogs with pyometra.

Expression of AMPK and PLIN2 in the regulation of lipid metabolism and oxidative stress in bitches with open cervix pyometra

The pathogenesis of canine pyometra is multifactorial, involving hormonal imbalances, aberrant immune responses, and metabolic dysregulation includes lipid metabolism and oxidative stress. This study focuses on lipid metabolism and oxidative stress, revealing the key regulatory role of AMPK and PLIN2 in canine pyometra. Bitches with open cervix pyometra (n:8) and healthy bitches undergoing elective ovariohysterectomy (n:4) were enrolled to the study. In experiment one, the serum and tissue levels of Malondialdehyde (MDA) and Superoxide Dismutase (SOD) activity were assessed. Additionally, uterine histopathological analysis, AMPK and PLIN2 expressions were determined through immunohistochemistry. Furthermore, inflammation, oxidative stress, and lipid metabolism-related factors were evaluated using Western blot analysis. In experiment two, primary cell cultures were prepared from healthy uterine endometrial cells of the dogs in control group. Cultured canine endometrial epithelial cells were treated with lipopolysaccharide (LPS) along with oleic acid (OA) to induce an inflammatory response. Tissue and serum MDA and SOD levels were greater in dogs with pyometra. Accumulated lipid droplets were observed in the uterine tissue of bitches with pyometra. The phosphorylation of AMPK and the expression of PLIN2 significantly increased in the pyometra group. The expression of related lipid synthesis proteins such as ACC1, FASN, SREBP-1c, and PLIN2 was upregulated, while PPARα and PGC1α were downregulated in bitches with pyometra. In experiment two, activation of AMPK and PLIN2 not only restores the expression of PGC1α, but also effectively alleviates inflammation and oxidative stress. The role of lipid metabolism and oxidative stress in canine pyometra is elucidated, thus contributing to the pathogenesis of pyometra in dogs.

Ultrasonographic computer-assisted quantification of the intraluminal uterine content in female dogs

In dogs, the characterization of intraluminal uterine contents has been subjectively carried out by the operators. The aims of this study were: 1) To ultrasonographically describe and compare the echogenicity and heterogeneity of the intraluminal uterine contents in bitches using digital analysis; 2) To assess the cytology of the uterine contents; 3) To evaluate the effect of clinical, ultrasonographic, bacteriological and cytological parameters on intraluminal contents echogenicity and heterogeneity. Twenty-one intact, 3-24 kg, 1-12 years of age, female dogs with ultrasonographically detected uterine content were included. According to the gross evaluation, the contents were classified as purulent (PC; n = 8), mucous (MC; n = 4), serous (SC; n = 9). Ultrasonographic images of the contents were digitally analyzed to measure echogenicity and heterogeneity, represented as the mean gray value (MGV) and the standard deviation of the gray value (SDG), respectively. Endometrial cytology samples were collected post-ovariohysterectomy. Clinical, ultrasonographic, bacteriological and cytological parameters were compared among groups using one way ANOVA and Chi-square tests. A generalized linear model was performed to analyze their effect on MGV and SDG. Uterine diagnoses included cystic endometrial hyperplasia - pyometra, cystic endometrial hyperplasia, cystic endometrial hyperplasia - mucometra, endometritis and normal uteruses. MGV was higher in PC and MC than in SC (P < 0.01), did not differ between PC and MC (P > 0.1). SDG was higher in PC than in SC (P < 0.01) and MC (P < 0.05). Digital analysis distinguished among purulent, mucous and serous fluids. Cytology revealed higher inflammation-related parameters in PC than in MC and SC. Cytological parameters, such as cellularity and bacterial presence, were associated with echogenicity and heterogeneity of uterine contents.

Genomic and phenotypic characterization of Chryseomicrobium imtechense from canine pyometra

Chryseomicrobium imtechense is a bacterium primarily isolated in environment samples. Here we demonstrated the virulent and antimicrobial resistant profile of the C. imtechense LBV029/19 strain, which was isolated in a pyometra infection in canines, being related as causal agent of that disease. The bacterium was recovered from purulent content of a uterus with pyometra and the identity was confirmed by both, biochemical tests followed MALDI-TOF MS and 16S-rDNA gene sequencing. Antimicrobial susceptibility test, biofilm formation assessment, genomic sequencing with Illumina MiSeq platform followed by the genome characterization and phylogenetic relationships were conducted with C. imtechense LBV029/19 strain. The phylogenetic analysis revealed a close evolutionary relationship between the C. imtechense LBV029/19 and the others publicly available 16S-rDNA genes of C. imtechense. The in vitro assays shown that C. imtechense LBV029/19 has a strong ability for biofilm formation. Additionally, the antimicrobial susceptibility tests revealed a smaller inhibition zone for novobiocin, cefuroxime, and erythromycin. To the best of our knowledge the C. imtechense LBV029/19 genome is the first genome sequenced and available of C. imtechense. Regarding the genotypic profile, resistance genes to tetracyclines, fluoroquinolones, beta-lactams, and multidrug resistance were present in this genome. Additionally, genes encoded to virulence factors, including biofilm formation, motility, and sporulation were identified. The phenotypic profile associated with the genotypic description indicates the potential of C. imtechense LBV029/19 as a primary agent of animal infectious diseases. The genomic description will contribute to the understanding of the biology of the bacterium and the pathogenesis process involved in the disease.

Bacteria associated with canine pyometra and concurrent bacteriuria: A prospective study

Canine pyometra is a common and potentially life-threatening reproductive disorder in intact female dogs. This prospective study aimed to (1) investigate the bacterial spectrum and antimicrobial susceptibilities of bacterial isolates from the uterus and urine of dogs with pyometra, (2) assess the clonal relatedness and virulence factors of Escherichia coli isolates from individual dogs, and (3) determine the occurrence of concurrent and persistent bacteriuria or clinical urinary tract infections. Bacterial isolates from 208 uterine and 203 urine specimens collected during pyometra surgery were analyzed. Additionally, follow-up urine specimens were collected from 56 dogs with perioperative bacteriuria. Bacterial growth was detected in 87 % (180/208) of uterine specimens, while concurrent bacteriuria was observed in 33 % (67/203) of cases. In one-third (18/56) of these dogs the bacteriuria persisted, being primarily (15/18) asymptomatic. E. coli was the most common isolate in both uterine (71 %) and urine (81 %) specimens. Notably, altogether 32 distinct bacterial species were identified, with mixed growth in 15 % of the specimens. The vast majority of isolates were largely susceptible to tested antimicrobials. Identification of bacterial species was performed using MALDI-ToF MS, and antimicrobial susceptibility was assessed by disk diffusion. Whole-genome sequencing of 45 E. coli strains from fifteen dogs indicated high genetic similarities within individual dogs, supporting a clonal relationship. In conclusion, canine uteri with pyometra contained a plethora of bacterial species, predominantly E. coli, and antimicrobial resistance was rare. Concurrent and persistent E. coli bacteriuria was commonly caused by the same clone as found in the uterus.

Effects of postoperative hyperbaric oxygen therapy on hematological and biochemical parameters in patients diagnoses with pyometra in sepsis

The aim of this study was to evaluate the impact of hyperbaric oxygen therapy (HBOT) on hematologic and biochemical markers in dogs with pyometra in sepsis. Eighteen patients were equally distributed between the control group (CG) and the hyperbaric group (HG). All patients underwent ovariohysterectomy, supportive therapy, and insertion of a central venous catheter. HG attended three HBOT sessions (2 absolute atmospheres, 45 min) postoperatively. Blood tests were performed on admission, 1 h postoperatively, 24 h, 48 ​​h, and 72 h postoperatively. Both groups showed a significant reduction in red blood cells (Hm) and hematocrit (Hto) after surgery, but this effect was reversed after three HBO sessions and maintained in CG. Despite the initial reduction in hemoglobin (Hg) in HG, the values ​​increased again after the end of the protocol. A reduction of >50 % in leukocytes was noted in HG in the last evaluation in relation to the values ​​at admission. Significant reduction was also found for neutrophils, metamyelocytes and rods in HG. There was no difference in biochemical markers. HBO associated with OVH and supportive therapy can be considered in the treatment of pyometra, with rapid and marked improvement, after three sessions, in the e red blood cells and leukogram.

The vaginal microbiota of healthy female cats

The vaginal microbiota of the queen (i.e., female cat) has never been described using culture independent methods. The objectives of the present research were to describe the vaginal microbiota of healthy domestic shorthair queens using both 16S rRNA sequencing and culture, and to assess the effects of age, living environment, and reproductive season on its composition. Thirty queens undergoing elective ovariectomy were included in the study. The vaginal samples were collected just before surgery, from animals under general anaesthesia. Two consecutive mini-swabs were introduced in the queens' vaginal tract. A preliminary study with 10 healthy queens aimed to negate sampling order's effect. Two consecutive samples for sequencing (5 queens, 10 swabs) and culture (5 queens, 10 swabs) were collected, confirming a match (100 % in culture, Bray-Curtis P = 0.96 in sequencing). The experiment included 20 queens that were prospectively grouped based on age (prepubertal N = 10, adult N = 10), living environment (indoor N = 10, outdoor N = 10), and time of the year, whether during the reproductive season (N = 10) or during seasonal anoestrous (N = 10). Bacteria were identified through metataxonomic analysis, amplifying the V1-V2 regions of 16S rRNA gene, and through standard culture followed by MALDI-TOF MS. The feline vaginal microbiota is dominated by Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteria. Escherichia-Shigella, Streptococcus, and Pasteurella were the most abundant genera. Although culture underestimated bacterial richness and diversity compared to sequencing, Escherichia and Streptococcus were the most isolated bacteria. No bacterial growth was observed in 15 % of samples (N = 3/20), whereas growth of one or two bacterial species was observed in 64.7 % (N = 11/17) and 35.3 % (N = 6/17) of cases, respectively. No differences in terms of alpha (Kruskal-Wallis rank sum test P = 0.65) and beta diversity (Bray-Curtis, Unweighted and Weighted UniFrac analyses P > 0.5) were observed. Although a difference in alpha diversity based on phylogenetic tree (P = 0.02) was detected between indoor and outdoor queens. In conclusion, mixed and monoculture of Escherichia coli, Streptococcus canis, Staphylococcus felis, and Enterococcus spp. are normal findings within the cat vagina. Age and reproductive season do not influence the feline vaginal microbiota, whereas further research is needed to elucidate the role of the living environment.

Antimicrobials administration, treatment outcome and bacterial susceptibility in canine pyometra cases subjected to ovariohysterectomy

Pyometra is a bacterial uterine infection that frequently affects intact older bitches. The treatment of choice is ovariohysterectomy, often associated with perioperative antimicrobial therapy. The aim of this retrospective investigation was to evaluate the antibiotic choice at different administration times (pre-surgery, at surgery/during hospitalization, and post-surgery) against complications and outcomes, considering the susceptibility profile of bacteria. The medical records of 51 bitches referred to the Veterinary Teaching Hospital of the University of Turin (January 2021-November 2023) and subjected to ovariohysterectomy and bacteriological examination (bacterial culture and susceptibility tests) of the uterine exudate, were analysed. All animals had a positive outcome without surgical site infections, with a longer hospitalization time in case of peritonitis or sepsis; antimicrobials were administered for an average of 7 days. Comparing the susceptibility of the isolated bacteria towards the antimicrobials administered before, during and after surgery, complete efficacy was observed in 42 %, 46 % and 50 % of cases, respectively. In addition, 5/16 peritonitis cases were treated with an in vitro ineffective antimicrobial, and 30 % of the bitches never received a fully effective antibiotic, according to susceptibility tests using the minimum inhibitory concentration method (MIC). Cephazolin resulted the best option for Escherichia coli, the most frequently isolated bacterium. Our study confirms that pyometra has a good prognosis following ovariohysterectomy and antibiotic administration. Monitoring the clinical evolution without changing the antibiotic according to bacterial susceptibility could represent the right choice in uncomplicated cases. Evaluation of outcomes without postoperative antibacterial treatment or with a shorter course would be another topic worth investigating, with the aim to judiciously reduce the use of antibiotics.

The reproductive microbiome in dogs: Friend or foe?

The microbiome of the reproductive tract is an area of research in full development. Specifically, the microbiome may be involved in reproductive health, disease, and pregnancy outcomes, as has been shown in humans and animals, including dogs. The aim of the present review was to summarize current knowledge on the microbiome of the canine reproductive tract, to expose the controversial role that some bacterial agents may play in canine subfertility, and to highlight future research perspectives. This review discussed whether the use of antimicrobials in dogs is appropriate to increase reproductive performance and to treat subfertility without proper diagnosis, and the possible use of probiotics to modulate the reproductive canine microbiome. Finally, we indicate areas in which scientific knowledge is currently lacking, and could be promising directions for future research.

Canine Pyometra: A Short Review of Current Advances

Pyometra, characterized by the accumulation of purulent exudate in the uterus, is the most prevalent reproductive disease in canines. While the disease often begins with mild local symptoms, it can escalate into peritonitis, sepsis, and multi-organ dysfunction, thereby posing a significant threat to life. Despite the high incidence and recognized significance of canine pyometra, gaps persist in our understanding of its epidemiology, etiology, and pathogenesis. Recent studies have, however, broadened our comprehension of this disease, shedding light on potential new infection sources, etiologies, and the application of clinical predictive biomarkers and new therapeutic protocols. This study aimed to review the current understanding of canine pyometra, with particular emphasis on the latest research concerning its etiology and epidemiology. Furthermore, it addressed key research questions and proposed directions for future investigations into various facets of canine pyometra.