Escherichia coli strains isolated from the uterus and urinary bladder of bitches suffering from pyometra: comparison by restriction enzyme digestion and pulsed-field gel electrophoresis

Comparative genetic and pathogenic approaches of Escherichia coli isolated simultaneously from pyometra and urine of bitches

Escherichia coli (E. coli) are widely related to pyometra and cystitis in dogs, and these infections can occur simultaneously. The goal of this study was to determine genetic and pathogenic insights of 14 E. coli isolated simultaneously from pyometra content and bladder urine of seven bitches. To achieve this, in silico and in vitro comparative analyses were conducted. Whole-genome comparisons demonstrated that E. coli isolated from pyometra and urine of the same animal were predominantly genetic extraintestinal E. coli clones belonging to the same Sequence Type and phylogroup. The E. coli clones identified in this study included ST372, ST457, ST12, ST127, ST646, and ST961. Five isolates (35.7%) belonged to the ST12 complex. Except for two E. coli, all other isolates belonged to the B2 Clermont phylogroup. Interestingly, some genomes of E. coli from urine carried more virulence genes than those E. coli from pyometra. Both pyometra and urine E. coli isolates demonstrated a strong affinity for adhering to HeLa and T24 cells, with a low affinity for invading them. However, certain isolates from urine exhibited a greater tendency to adhere to T24 cells in qualitative and quantitative assays compared to isolates from pyometra. In conclusion, this study revealed the high genomic similarity between pyometra and urine E. coli isolates, as well as the virulent capacity of both to colonize endometrial and urothelial cells. The findings of this study underscore the importance of concurrently managing both infections clinically and could potentially contribute to future resources for the prevention of cystitis and pyometra.

Escherichia coli isolated from pyometra and cystitis in the same animal exhibit a wide phenotypic similarity

AIMS

Pyometra and cystitis caused by Escherichia coli are common diseases identified in canine or feline females. The origin of pyometra infection remains uncertain, and effective prevention strategies for this disease are still unknown. This study aimed to provide a phenotypic characterization, including antimicrobial resistance and virulence profiles, of endometrial pathogenic (EnPEC) and uropathogenic (UPEC) E. coli strains isolated simultaneously from the same animal.

METHODS AND RESULTS

Sixteen E. coli strains, from eight different animals, were analyzed in this study. The antimicrobial susceptibility profile of EnPEC and UPEC strains was determined using the disc diffusion method, which showed a similar susceptibility profile among strains (EnPEC and UPEC) from the same animal. The virulence profile of the strains was assessed through biofilm formation, as well as serum resistance abilities. EnPEC and UPEC strains from the same animal exhibited slight variations in their virulence and antimicrobial resistance capabilities. Overall, most of the strain pairs showed a high similarity in their ability to establish biofilms and survive in serum complement activity.

CONCLUSIONS

Overall, strains of E. coli isolated from both pyometra and cystitis in the same animal, despite presenting distinct clinical diseases, exhibit a wide phenotypic similarity, suggesting a common origin for the strains.

Effect of pyometra on vascularity alterations, oxidative stress, histopathology and inflammatory molecules in feline

This study aimed to investigate blood flow, hemodynamical features by Doppler ultrasound, the oxidative stress biomarkers from serum samples, and histopathology from uterine tissue, in healthy queens and queens with pyometra. Twenty queens were categorized into two groups, according to signs, history, and ultrasound findings, as pyometra and control healthy queens. Doppler ultrasonography, total antioxidant capacity (TAC), malondialdehyde (MDA), albumin, bacteriological isolation, histopathology, and immunohistochemistry of tumor necrosis factor-alpha (TNF-α) and nuclear factor kappa B (NF-κB) P65 were performed. Uterine diameter and thickness increased significantly in the pyometra group compared to control. Uterine peak velocity and flow rate were significantly higher in the control group. The pyometra group showed a significant decrease in albumin, TAC, and a significant increase in MDA. Fibrosis and mononuclear inflammatory cell infiltration were seen in the pyometra samples. The mean area percentage of TNF-α expression in the uteri of the pyometra group was higher. The expression of NF-κB P65 in the uteri in the pyometra group was significantly higher. Doppler ultrasonography can provide valuable information for diagnosing pyometra in queens by elevating the uterine thickness with reducing blood flow rate. Oxidative stress, TNF-α, and NF-κB expression alterations varied between pyometra and control groups.

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.

Pyometra in Small Animals 3.0

Pyometra is a common disease in intact bitches and queens and occurs, although less frequently, in most other female pets. In bitches and queens, the illness is generally diagnosed within 4 months after estrus, in middle-aged to older individuals. Complications such as peritonitis, endotoxemia, and systemic inflammatory response syndrome are not uncommon and associated with more severe illness. Ovary-sparing surgical options such as hysterectomy could be considered in individuals with high-risk for detrimental side effects of spaying or without infection of the uterus but has not yet been evaluated for safety in pyometra.

Antimicrobial use in the surgical treatment of canine pyometra: A questionnaire survey of Arizona-licensed veterinarians

BACKGROUND

Recent studies and consensus statements in veterinary and human medicine recommend more judicious use of antimicrobials. While guidelines have been provided for some veterinary diseases, others have poorly elucidated guidelines. Postoperative treatment of canine pyometra is a condition with minimal guidelines regarding antimicrobial use.

OBJECTIVE

To identify and investigate patterns of antimicrobial use following surgically treated canine pyometra.

METHODS

A 23-question survey, sent to 863 small and mixed animal practitioners, investigated demographics, patterns of antibiotic use, rate of culture submission and participant's recollection of outcomes of surgically treated pyometra cases. Responses were analysed for relationships between demographics, patterns of antibiotic use and culture results to better understand reasoning for antibiotic protocols.

RESULTS

One hundred and fifty-two responses were received. Overall, 76% of veterinarians stated they always use preoperative and perioperative antibiotics, and 74% stated they always use postoperative antibiotics. A total of 16 different antibiotics were reported. Twelve per cent of respondents regularly submitted a culture. Culture submission was impacted by cost, prior experience, poor owner compliance, result turnaround time and anticipated results.

CONCLUSIONS

Most respondents always used antibiotics and rarely or never submitted a culture. To optimise patient care, future clinical studies are needed to determine specific guidelines for the use of culture and antibiotics in the treatment of canine pyometra following ovariohysterectomy.

Phylogeny and Virulence Factors of Escherichia coli Isolated from Dogs with Pyometra

We aimed to investigate the occurrence, phylogeny, and virulence of E. coli in the uterine contents and urine of female dogs with pyometra, through the presence of virulence genes and their genetic similarity. Uterine secretions and urine samples from 52 female dogs with pyometra were collected and cultured. Strains identified as E. coli from 25 uterine and 7 urine samples were tested for virulence genes by PCR. Genetic similarity between the isolates was studied using RAPD-PCR. E. coli was observed in 48.07% uterine samples with pyometra and 20.0% urine samples. The strains showed high percentages for the presence of virulence genes: 96.9% had the gene sfa, 59.4% afa, 46.9% pap, 53.1% hly, and 68.75% cnf. Even with the high prevalence of virulence genes, the samples were not submitted to DNA sequencing to confirm the results. Analysis showed high genetic diversity in E. coli, however, strains isolated from the same animal indicate that cystitis and pyometra could be related. Our study indicated the association between E. coli in dogs with pyometra and cases of urinary tract infection and the pathogenic potential of strains increasing with animal age.

Successful Treatment of Pyometra Caused by Pseudomonas aeruginosa Infection in a Rabbit

This article reports an unusual presentation of pyometra in a pet rabbit. A 2-year-old mixed-breed female rabbit with pelvic limb paralysis was referred for abdominal distension associated with prolonged depression and decreased appetite. Clinical examination and diagnostic imaging (radiographs and ultrasound) led to the provisional diagnosis of pyometra that was caused by the presence of an enlarged organ containing fluid material and occupying most of the caudal abdomen. Exploratory laparotomy was performed under general anesthesia. After abdominal wall incision along the linea alba, the uterus was immediately evident and the uterine wall was over-distended and damaged, with purulent material free in the abdominal cavity. Ovariohysterectomy was performed and uterine wall samples were sent for microbiological examination and antimicrobial susceptibility testing. The agent causing the pyometra was found to be Pseudomonas aeruginosa, which was resistant to enrofloxacin and ceftazidime. This is the first report of pyometra caused by P. aeruginosa in a pet rabbit, based on a literature search. Furthermore, a peculiarity of the present case is the occurrence of pyometra in a rabbit with no history of mating or parturition.

The endometrium histopathology and cell ultrastructure in bitches with pyometra induced using progesterone and Escherichia coli

BACKGROUND

We investigated uterine histopathological and ultrastructural changes in female dogs with pyometra induced by Escherichia coli (E. coli) inoculation using progesterone and/or estradiol.

METHODS

Dogs were ovariectomized and classified into six groups: Groups 1-6 corresponding to estradiol treatment followed by progesterone supplementation, progesterone supplementation only, estradiol supplementation only, simultaneous treatment using estradiol and progesterone, similar to Group 1 but with a double dose, and control group, respectively.

RESULTS

Pyometra was successfully induced in Groups 1, 2, 4, and 5, but not in Group 3. An uneven endometrial surface was observed, along with a purulent discharge, bleeding, inflammatory lesions, cystic endometrial hyperplasia (CEH) or cystic endometrial atrophy. Endometrial thickness percentage, uterine wall thickness, and the percentage of endometrial cyst area increased. Endometrial epithelial mushroom-like hyperplasia and the honeycomb-like structure exposed under the epithelium after flaky exfoliation were found, and the glandular epithelial villi became longer or shorter. Mitochondria expansion and increased lysosome were observed. Endoplasmic reticulum dilation and swelling and many inflammatory cells, especially plasma cell infiltration in the stroma, were found.

CONCLUSIONS

Endometrial histopathology and ultrastructural changes in affected dogs were accompanied by induction of pyometra, and they were affected by different hormonal patterns and E. coli.

Evaluation of Biofilm Production by Escherichia coli Isolated From Clinical Cases of Canine Pyometra

Many Escherichia coli (E. coli) strains produce biofilm that confers antimicrobial resistance. However, studies of biofilm production by E. coli from canine pyometra are lacking. Objectives were to elucidate the role of biofilm production by E. coli in pyometra by: (1) assessing the ability of E. coli to produce biofilm in vitro, and (2) confirming biofilm in situ. Endometrial biopsies were obtained from bitches with pyometra and preserved for microscopic analysis (n = 25). An endometrial swab was submitted for aerobic culture. Samples with confirmed E. coli were evaluated further for biofilm production in vitro and in vivo. Seventy percent of cases (16/23) resulted in pure growth of 1 or 2 E. coli strains, totaling 20 isolates. Fifteen isolates (15/20, 75%) had higher optical densities then negative controls (P < .05). On histopathology, all tissues exhibited endometrial inflammation and mucus was located within endometrial glands and occasionally overlying epithelium on 14 slides (14/16, 88%). Bacteria was noted in 50% of slides (8/16). During FISH acellular debris within the uterine lumen consistent with biofilm was noted on 94% of samples (15/16) and E coli was positively identified on all samples (15/15). Areas suggestive of the presence of biofilm were observed on all samples on scanning electron microscopy; but, bacteria consistent with E. coli were only visualized in 9 samples (9/16, 56%). In conclusion, we demonstrated that relevant strains of E. coli produce biofilm in vitro and in vivo, which may be considered in the development of new pyometra treatments aimed at disrupting these E. coli biofilm.

PIOMETRAS EM CADELAS: RELAÇÃO ENTRE O PROGNÓSTICO CLÍNICO E O DIAGNÓSTICO LABORATORIAL

Resumo Piometra é uma afecção resultante da interação bacteriana com a hiperplasia cística do endométrio. O objetivo deste estudo foi identificar bactérias em condições de aerobiose e anaerobiose da secreção intrauterina de cadelas com piometra, presença da síndrome da resposta inflamatória sistêmica, status da cérvix, peritonite, dosagens bioquímicas séricas e comparar com o prognóstico de cadelas tratadas cirurgicamente. Utilizaram-se 15 cadelas com piometra, submetidas à ovariohisterectomia. Hemogramas e dosagens séricas de ureia, creatinina, FA e ALT foram realizados no pré-operatório imediato. Coletou-se urina por cistocentese. Após a remoção do útero e ovários, a secreção intrauterina foi aspirada; as amostras foram então cultivadas em aerobiose e anaerobiose, as amostras de urina em aerobiose. Os animais foram divididos em dois grupos, G1 (alta hospitalar em até 48 horas) e G2 (alta hospitalar após 48 horas ou óbito). Onze amostras de conteúdo intrauterino (73,3%) apresentaram crescimento bacteriano em aerobiose e anaerobiose e em uma amostra isolou-se Arizona hinshawii. Quatro amostras de urina (26,6%) tiveram crescimento bacteriano. Houve diferença significativa das variáveis status da cérvix, ureia, creatinina e fosfatase alcalina entre G1 e G2. Embora a diversidade etiológica encontrada nas culturas de conteúdo intrauterino tenha sido alta, a avaliação da azotemia, status da cérvix e dosagem de FA sérica mostraram-se bons marcadores prognósticos em cadelas com piometra.

Immunomodulation in the canine endometrium by uteropathogenic Escherichia coli

This study was designed to evaluate the role of E. coli α-hemolysin (HlyA) in the pathogenesis of canine pyometra, and on the immune response of canine endometrial epithelial and stromal cells. In Experiment 1, the clinical, hematological, biochemical and uterine histological characteristics of β-hemolytic and non-hemolytic E. coli pyometra bitches were compared. More (p < 0.05) metritis cases were observed in β-hemolytic E. coli pyometra uteri than in non-hemolytic E. coli pyometra uteri. β-hemolytic E. coli pyometra endometria had higher gene transcription of IL-1β and IL-8 and lower gene transcription of IL-6 than non-hemolytic E. coli pyometra endometria (p < 0.01). In Experiment 2, the immune response of endometrial epithelial and stromal cells, to hemolytic (Pyo18) and non-hemolytic E. coli strains (Pyo18 with deleted hlya-Pyo18ΔhlyA- and Pyo14) were compared. Following 4 h of incubation, Pyo18 decreased epithelial cell numbers to 54% (p < 0.001), and induced death of all stromal cells (p < 0.0001), whereas Pyo18ΔhlyA and Pyo14 had no effect on cell numbers. Compared to Pyo18ΔhlyA and Pyo14, respectively, Pyo18 induced a lower transcription level of IL-1β (0.99 vs 152.0 vs 50.9 fold increase, p < 0.001), TNFα (3.2 vs 49.9 vs 12.9 fold increase, p < 0.05) and IL-10 (0.4 vs 3.6 vs 2.6 fold increase, p < 0.001) in stromal cells, after 1 h of incubation. This may be seen as an attempt of hemolytic E. coli to delay the activation of the immune response. In conclusion, endometrial epithelial and stromal cell damage induced by HlyA is a potential relevant step of E. coli virulence in the pathogenesis of pyometra.

Intrigues of biofilm: A perspective in veterinary medicine

Biofilm has a tremendous impact in the field of veterinary medicine, especially the livestock industry, leading to a serious economic loss. Over the years, little attention has been given to biofilm in animals with most of the research geared toward human biofilm diseases. The greatest challenge posed by biofilm is in its incredible ability to resist most of the currently existing antibiotics. This mystery can best be demystified through understanding the mechanism of the quorum sensing which regulate the pathophysiology of biofilm. Ability of biofilm formation in a variety of inanimate surfaces such as animal food contact surfaces is responsible for a host of biofilm diseases affecting animals and humans. In this review, we highlighted some of the challenges of biofilm in livestock and food industries. Also highlighted are; mechanisms of biofilm development, best diagnostic approach and possible novel therapeutic measures needed to combat the menace of biofilm in veterinary medicine.

Phylo-typing of clinical Escherichia coli isolates originating from bovine mastitis and canine pyometra and urinary tract infection by means of quadruplex PCR

BACKGROUND

Escherichia coli is one of the major causative agents of bovine mastitis worldwide, and is typically associated with acute, clinical mastitis. Besides this, E. coli strains which belong to the extra-intestinal pathogenic group are also the major cause of urinary tract infections and pyometra in dogs.

OBJECTIVES

In this study, it was aimed to investigate phylo-groups/subgroups in 155 E. coli isolates obtained from acute bovine mastitis, 43 from urinary tract infections of dogs and 20 from canine pyometra by a formerly described triplex PCR and recently described new quadruplex polymerase chain reaction (PCR) method.

RESULTS

Group A1 (n = 118; 76%) and B1 (n = 71; 46%) were found to be the most prevalent groups by triplex and quadruplex PCR assays in mastitis isolates, respectively. Phylo-typing of 43 urinary tract isolates also revealed that most of the isolates belonged to A1 (n = 23; 54%) by triplex and B2 (n = 36; 84%) by quadruplex PCR assays. The isolates assigned as group A1 (n = 17; 85%) by triplex PCR could not be classified by quadruplex PCR in pyometra isolates.

CONCLUSIONS

The results support the hypothesis that E. coli strains isolated from bovine mastitis cases are environmental. Also, groups C, E and F were identified as new phylo-groups for the first time in acute bovine mastitis cases. The comparison of triplex PCR with quadruplex PCR results revealed that most of the groups assigned in triplex PCR were altered by quadruplex PCR assay.

Effect of six fluoroquinolones on the expression of four efflux pumps in the multidrug resistant Escherichia coli isolates

In this study, a total of 78 Escherichia coli clinical isolates were isolated from canines diagnosed with urinary tract infections. 23/78 isolates (29.5 %) showed multidrug resistance (MDR) phenotype, including the isolates both susceptible to fluoroquinolones (FQs) (FQ(S)-MDR, n = 12) and resistant to FQs (FQ(R)-MDR, n = 11). For these MDR isolates, mutations within quinolone-resistance determining region of gyrA and parC were determined by PCR amplification and DNA sequencing. The relative quantification of emrE, acrB, macB, and mdfA genes expression in MDR isolates was determined by quantitative real-time PCR before and after exposure to the FQs (10 µg/ml). The results showed that a temporary exposure to FQs could lead to various degrees of up or down-regulation on the expression of four efflux pumps in MDR isolates depending on the resistant phenotype and the activities of the FQs. Generally, the FQ(R)-MDR isolates showed more obvious changes in average expression levels of these transporters versus the FQ(S)-MDR isolates, with a largest increase in emrE, and followed by acrB, while the expression of macB and mdfA did not change as radically. Meanwhile, there is a reverse relationship between the expression changes and the activities of the FQs tested. The expression was higher in the isolates exposed to enrofloxacin, ciprofloxacin, and orbifloxacin, and followed by the marbofloxacin, gatifloxacin, and pradofloxacin, and the average expression levels of some efflux pumps even decreased as the isolates were exposed to gatifloxacin or pradofloxacin.

Medical treatment for pyometra in dogs

Pyometra is a reproductive disorder very common in bitches over 8 years of age in which physiological effects of progesterone on the uterus play a major role. The traditional therapy for pyometra is ovariohysterectomy. The main advantage of ovariohysterectomy over medical management is that it is both curative and preventive for recurrence of pyometra. However, surgery is associated with the risk of anaesthesia and renders the bitch sterile. During the last 10 years, numerous medical treatments have been proposed to treat both open and closed cervix pyometra. The most effective medical treatment with minor side effects seems to be the repeated administration of aglepristone with or without the additional treatment with low doses of prostaglandins.

Pathogenic Escherichia coli and lipopolysaccharide enhance the expression of IL-8, CXCL5, and CXCL10 in canine endometrial stromal cells

Chemokines play a central role in cellular communication in response to bacterial infection. However, the knowledge of the chemokine responses to bacterial infections in dogs remains limited. Uterine bacterial infection (pyometra) is one of the most common bacterial diseases in dogs and causes sepsis in most of the cases. We have shown previously that dogs with pyometra have higher messenger RNA (mRNA) levels of chemokines in uterus. To assess whether the stromal part of the endometrium expresses chemokines in response to bacterial infection, we cultured endometrial stromal cells isolated from healthy dogs and exposed them to either live pathogenic Escherichia coli, isolated from the uterus of a dog with pyometra, or lipopolysaccharide. Changes in the mRNA expression of ELR(+) CXC chemokines, IL-8, CXCL5, CXCL7, and ELR(-) CXC chemokine, CXCL10, were measured after 24 hours using quantitative real-time polymerase chain reaction. Levels of IL-8, CXCL5, and CXCL10 were upregulated in endometrial stromal cells exposed to E coli and lipopolysaccharide, whereas the level of CXCL7 was decreased or unaffected. In addition, levels of IL-8 and CXCL5, but not CXCL7 or CXCL10, were significantly higher in dogs with pyometra than those in healthy dogs. Our findings show that pathogenic uterine-derived E coli induces a CXC chemokine response both in cultured endometrial stromal cells within 24 hours and in pyometra-affected uteri from dogs. Stromal cells could therefore play an important role in early neutrophil and T cell recruitment to the site of inflammation during gram-negative bacterial infection of the uterus. Further studies are needed to clarify the role of chemokines in host response to bacterial infection in dogs and the possibility of using chemokines as diagnostic parameters for bacterial infection in this species.

Antimicrobial resistance of Escherichia coli isolates from canine urinary tract infections

This study determined the antimicrobial resistance profiles of Escherichia coli isolates from dogs with a presumptive diagnosis of urinary tract infection (UTI). Urine samples from 201 dogs with UTI diagnosed through clinical examination and urinalysis were processed for isolation of Escherichia coli. Colonies from pure cultures were identified by biochemical reactions (n=114) and were tested for susceptibility to 18 antimicrobials. The two most frequent antimicrobials showing resistance in Urinary E. coli isolates were oxytetracycline and ampicillin. Among the resistant isolates, 17 resistance patterns were observed, with 12 patterns involving multidrug resistance (MDR). Of the 69 tetracycline-resistant E. coli isolates, tet(B) was the predominant resistance determinant and was detected in 50.9% of the isolates, whereas the remaining 25.5% isolates carried the tet(A) determinant. Most ampicillin and/or amoxicillin-resistant E. coli isolates carried bla_TEM-1 genes. Class 1 integrons were prevalent (28.9%) and contained previously described gene cassettes that are implicated primarily in resistance to aminoglycosides and trimethoprim (dfrA1, dfrA17-aadA5). Of the 44 quinolone-resistant E. coli isolates, 38 were resistant to nalidixic acid, and 6 were resistant to nalidixic acid, ciprofloxacin and enrofloxacin. Chromosomal point mutations were found in the GyrA (Ser83Leu) and ParC (Ser80Ile) genes. Furthermore, the aminoglycoside resistance gene aacC2, the chloramphenicol resistant gene cmlA and the florfenicol resistant gene floR were also identified. This study revealed an alarming rate of antimicrobial resistance among E. coli isolates from dogs with UTIs.

Frequencies of virulence genes and pulse field gel electrophoresis fingerprints in Escherichia coli isolates from canine pyometra

Escherichia coli is the most common bacterial agent isolated from canine pyometra. The frequencies of 24 virulence genes and pulsed field gel electrophoresis (PFGE) profiles were determined for 23 E. coli isolates from cases of canine pyometra in Brazil. The frequencies of virulence genes were 91.3% fimH, 91.3% irp-2, 82.6% fyuA, 56.5% iroN, 47.8% traT, 39.1% usp, 34.8% sfaD/E, 34.8% tsh, 30.4% papC, 30.4% hlyA, 26.1% papGIII, 26.1% cnf-1, 21.7% papE/F, 21.7% iss, 17.4% iutA, 17.4% ompT, 17.4% cvaC, 17.4% hlyF, 17.4% iucD, 13.0% iucC, 13.0% astA, 4.3% papGII, 0% afaB/C and 0% papGI. The high frequency of yersiniabactin (fyuA and irp2) and salmochelin (iroN) genes suggests that iron uptake systems might be important in the pathogenesis of canine pyometra. PFGE profiles of 19 isolates were heterogeneous, confirming that E. coli isolates from canine pyometra are unlikely to be epidemic clones.

Escherichia coli Strains Isolated from the Uteri Horn, Mouth, and Rectum of Bitches Suffering from Pyometra: Virulence Factors, Antimicrobial Susceptibilities, and Clonal Relationships among Strains

Pyometra is recognized as one of the main causes of disease and death in the bitch, and Escherichia coli is the major pathogen associated with this disease. In this study, 70 E. coli isolates from the uteri horn, mouth, and rectum of bitches suffering from the disease and 43 E. coli isolates from the rectum of clinically healthy bitches were examined for the presence of uropathogenic virulence genes and susceptibility to antimicrobial drugs. DNA profiles of isolates from uteri horn and mouth in bitches with pyometra were compared by REP, ERIC, and BOX-PCR. Virulence gene frequencies detected in isolates from canine pyometra were as follows: 95.7% fim, 27.1% iss, 25.7% hly, 18.5% iuc, and 17.1% usp. Predominant resistance was determined for cephalothin, ampicillin, and nalidixic acid among the isolates from all sites examined. Multidrug resistance was found on ∼50% pyometra isolates. Using the genotypic methods some isolates from uteri, pus, and saliva of the same bitch proved to have identical DNA profiles which is a reason for concern due to the close relationship between household pets and humans.

Chromosomal and plasmid-mediated fluoroquinolone resistance mechanisms among broad-spectrum-cephalosporin-resistant Escherichia coli isolates recovered from companion animals in the USA

OBJECTIVES

To determine the prevalence of plasmid-mediated quinolone resistance (PMQR) determinants and investigate mutations in gyrase and topoisomerase genes that may contribute to increased fluoroquinolone resistance in canine and feline Escherichia coli isolates in the USA that displayed reduced susceptibility to extended-spectrum cephalosporins. This study was undertaken because previous epidemiological studies identified a potential correlation between extended-spectrum cephalosporins and fluoroquinolone resistance.

METHODS

Isolates (n = 54) with reduced susceptibility to ceftazidime or cefotaxime were screened by PCR for the presence of PMQR determinants and gyrase and topoisomerase genes were sequenced. Isolates were further characterized by conjugation and phylogenetic analyses.

RESULTS

PMQR determinants aac(6')-Ib-cr, qnrS and qepA were identified in 30, 23 and 5 isolates, respectively. Multiple mutations were identified in the quinolone resistance-determining region, including the novel substitutions of Glu-84 → Ala and Leu-88 → Gln in ParC and Arg-432 → Ser and Glu-460 → Val in ParE. The isolate that exhibited the highest level of enrofloxacin resistance (MIC > 256 mg/L) had a double mutation in gyrA (Ser-83 → Leu and Asp-87 → Asn) and a triple mutation in parC (Ser-80 → Ile, Glu-84 → Gly and a novel mutation, Leu-88 → Gln). The presence of PMQR genes increased the ciprofloxacin MIC values 4-fold to 8-fold in transconjugants relative to the recipient strain. Approximately 39% of the isolates belonged to phylogenetic group D and 30% to group B2, which typically contain an increased number of virulence determinants compared with other groups.

CONCLUSIONS

Novel mutations in topoisomerase genes and PMQR determinants aac(6')-Ib-cr, qnrS and qepA genes were detected among extended-spectrum β-lactamase-producing E. coli in the USA.

Pathogenic Escherichia coli found in sewage treatment plants and environmental waters

We previously demonstrated that some Escherichia coli strains with uropathogenic properties survived treatment stages of sewage treatment plants (STPs), suggesting that they may be released into the environment. We investigated the presence of such strains in the surrounding environmental waters of four STPs from which these persistent strains were isolated. In all, 264 E. coli isolates were collected from 129 receiving water sites in a 20-km radius surrounding STPs. We also included 93 E. coli strains collected from 18 animal species for comparison. Isolates were typed using a high-resolution biochemical fingerprinting method (the PhPlate system), and grouped into common (C) types. One hundred forty-seven (56%) environmental isolates were identical to strains found in STPs' final effluents. Of these, 140 (95%) carried virulence genes (VGs) associated with intestinal pathogenic E. coli (IPEC) or uropathogenic E. coli (UPEC) and were found in a variety of sites within areas sampled. Of the remaining 117 environmental strains not identical to STP strains, 105 belonged to 18 C types and 102 of them carried VGs found among IPEC or UPEC strains. These strains belonged mainly to phylogenetic groups A (A0 and A1) and B1 and to a lesser extent B2(2), B2(3), D1, and D2. Eight of 18 environmental C types, comprising 50 isolates, were also identical to bird strains. The presence of a high percentage of environmental E. coli in waters near STPs carrying VGs associated with IPEC and UPEC suggests that they may have derived from STP effluents and other nonpoint sources.

Molecular characterization of resistance to extended-spectrum cephalosporins in clinical Escherichia coli isolates from companion animals in the United States

Resistance to extended-spectrum cephalosporins (ESC) among members of the family Enterobacteriaceae occurs worldwide; however, little is known about ESC resistance in Escherichia coli strains from companion animals. Clinical isolates of E. coli were collected from veterinary diagnostic laboratories throughout the United States from 2008 to 2009. E. coli isolates (n = 54) with reduced susceptibility to ceftazidime or cefotaxime (MIC ≥ 16 μg/ml) and extended-spectrum-β-lactamase (ESBL) phenotypes were analyzed. PCR and sequencing were used to detect mutations in ESBL-encoding genes and the regulatory region of the chromosomal gene ampC. Conjugation experiments and plasmid identification were conducted to examine the transferability of resistance to ESCs. All isolates carried the bla(CTX-M-1)-group β-lactamase genes in addition to one or more of the following β-lactamase genes: bla(TEM), bla(SHV-3), bla(CMY-2), bla(CTX-M-14-like), and bla(OXA-1.) Different bla(TEM) sequence variants were detected in some isolates (n = 40). Three isolates harbored a bla(TEM-181) gene with a novel mutation resulting in an Ala184Val substitution. Approximately 78% of the isolates had mutations in promoter/attenuator regions of the chromosomal gene ampC, one of which was a novel insertion of adenine between bases -28 and -29. Plasmids ranging in size from 11 to 233 kbp were detected in the isolates, with a common plasmid size of 93 kbp identified in 60% of isolates. Plasmid-mediated transfer of β-lactamase genes increased the MICs (≥ 16-fold) of ESCs for transconjugants. Replicon typing among isolates revealed the predominance of IncI and IncFIA plasmids, followed by IncFIB plasmids. This study shows the emergence of conjugative plasmid-borne ESBLs among E. coli strains from companion animals in the United States, which may compromise the effective therapeutic use of ESCs in veterinary medicine.

Changes in CRP, SAA and haptoglobin produced in response to ovariohysterectomy in healthy bitches and those with pyometra

The aim of the study was to assess changes in serum C-reactive protein (CRP), serum amyloid A component (SAA) and haptoglobin (Hp) concentrations in healthy bitches and in those with pyometra undergoing ovariohysterectomy, and to establish the usefulness of such determinations for monitoring the postoperative period. Our results indicate that CRP and SAA determinations serve to evaluate the severity of the inflammatory process in pyometra since the concentrations of these acute phase proteins were increased immediately after surgery and diminished thereafter. The CRP and SAA response was rapidly produced while Hp concentrations increased in a more gradual manner. Thus, postoperative concentrations of CRP and SAA provide valuable information on the subsidence of the inflammatory response during the uneventful postoperative period. Our findings also suggest that acute phase proteins might be useful diagnostic markers of early postoperative complications.

Pyometra in bitches induces elevated plasma endotoxin and prostaglandin F2alpha metabolite levels

Endotoxemia in bitches with pyometra can cause severe systemic effects directly or via the release of inflammatory mediators. Plasma endotoxin concentrations were measured in ten bitches suffering from pyometra with moderately to severely deteriorated general condition, and in nine bitches admitted to surgery for non-infectious reasons. Endotoxin samples were taken on five occasions before, during and after surgery. In addition, urine and uterine bacteriology was performed and hematological, blood biochemical parameters, prostaglandin F2alpha metabolite 15-ketodihydro-PGF2alpha (PG-metabolite), progesterone and oestradiol (E2-17beta) levels were analysed. The results confirm significantly increased plasma levels of endotoxin in bitches with pyometra and support previous reports of endotoxin involvement in the pathogenesis of the disease. Plasma concentrations of PG-metabolite were elevated in pyometra bitches and provide a good indicator of endotoxin release since the concentrations were significantly correlated to the endotoxin levels and many other hematological and chemistry parameters. The gamma-globulin serum protein electrophoresis fraction and analysis of PG-metabolite can be valuable in the diagnosis of endotoxin involvement if a reliable, rapid and cost-effective test for PG-metabolite analysis becomes readily available in the future. Treatment inhibiting prostaglandin biosynthesis and related compounds could be beneficial for bitches suffering from pyometra.

Antimicrobial properties and phytochemical constituents of the leaves of African mistletoe (Tapinanthus dodoneifolius (DC) Danser) (Loranthaceae): an ethnomedicinal plant of Hausaland, Northern Nigeria

African mistletoe (Tapinanthus dodoneifolius (DC) Danser) called 'Kauchi' in Hausa is a hemi-plant parasite used ethnomedicinally by the Hausa and the Fulani tribes of Northern Nigeria as a remedy for several human and animal ailments that include stomach ache, diarrhoea, dysentery, wound and cancer. Screening of the plant, obtained from 14 different hosts, revealed a wide spectrum of antimicrobial activities against certain multiple drug resistant bacterial and fungal isolates of farm animals. Interestingly, the inhibition of the growth of Agrobacterium tumefaciens, Bacillus sp., Escherichia coli, Salmonella sp., Proteus sp. and Pseudomonas sp., bacterial sp. known to be associated with either crown gall or gastrointestinal tract and wound infections, by extracts of T. dodoneifolius gives credence to the ethnomedicinal usage of the plant. Phytochemical screening showed the common occurrence of anthraquinones, saponins, and tannins, a rare presence of alkaloids and the absence of phlobatannins in the hemi-parasite. Moreover, the antimicrobial activity and the presence or distribution of phytochemical substances in T. dodoneifolius appeared to be partly dependent on the host plant species.