Serotype O3 Research Articles

Isolation and characterization of a broad-spectrum bacteriophage against multi-drug resistant Escherichia coli from waterfowl field.

Escherichia coli (E. coli) is a significant pathogen responsible for intestinal infections and foodborne diseases. The rise of antibiotic resistance poses a significant challenge to global public health. Traditional antibiotic therapy is becoming increasingly ineffective, highlighting the urgent need for innovative control strategies. This study explores the potential of bacteriophages as a sustainable alternative to traditional antibiotics. From 2021 to 2022, a total of 183 non-repetitive duck source fecal samples were collected from Mianyang City, Sichuan Province, and 126 strains of E. coli were isolated. The minimum inhibitory concentration (MIC) test showed that these strains exhibited high resistance to piperacillin (96.8%), tetracycline (88.9%), and chloramphenicol (86.5%). It is concerning that 93.7% of the isolates are classified as multidrug-resistant (MDR), posing a significant threat to existing treatment options. 20 bacteriophages were isolated from fecal and soil samples, among which 5 bacteriophages were selected for further analysis. Bacteriophage YP6 showed excellent lytic effects on MDR strains, especially strain MY104, as well as representative serotypes O1 (E. coli MY51) and O18 (E. coli MY106). The identification of YP6 as a member of the Myoviridae family was conducted using transmission electron microscopy, and it was found to have an optimal infection factor of 0.1. Bacteriophages exhibit significant thermal and pH stability, maintaining survival at temperatures up to 60 °C and pH ranges of 4 to 10. Whole genome sequencing confirmed that YP6 has a double stranded DNA genome of 139,323 base pairs (bp), and no antibiotic resistance or virulence genes were found, indicating a low possibility of horizontal gene transfer. In addition, YP6 effectively inhibits the formation of E. coli biofilm, which is a key factor in chronic infections. The in vivo experiments using Galleria mellonella (G. mellonella) larvae have shown that it has a significant protective effect against MDR E. coli infection. In summary, bacteriophage YP6 is expected to become a therapeutic agent against MDR E. coli infection due to its broad host range, environmental stability, and biofilm inhibition properties. Future research should optimize bacteriophage preparations, evaluate the safety and efficacy of animal models, and establish clinical application plans in the field of food safety.

An outbreak of Shiga toxin-producing Escherichia coli serotype O103:H2 associated with unpasteurized soft cheese, England and Wales, 2022.

In July 2022, a genetically linked and geographically dispersed cluster of 12 cases of Shiga toxin-producing Escherichia coli (STEC) O103:H2 was detected by the UK Health Security Agency using whole genome sequencing. Review of food history questionnaires identified cheese (particularly an unpasteurized brie-style cheese) and mixed salad leaves as potential vehicles. A case-control study was conducted to investigate exposure to these products. Case food history information was collected by telephone. Controls were recruited using a market research panel and self-completed an online questionnaire. Univariable and multivariable analyses were undertaken using Firth Logistic Regression. Eleven cases and 24 controls were included in the analysis. Consumption of the brie-style cheese of interest was associated with illness (OR 57.5, 95% confidence interval: 3.10-1,060). Concurrently, the production of the brie-style cheese was investigated. Microbiological sample results for the cheese products and implicated dairy herd did not identify the outbreak strain, but did identify the presence of stx genes and STEC, respectively. Together, epidemiological, microbiological, and environmental investigations provided evidence that the brie-style cheese was the vehicle for this outbreak. Production of unpasteurized dairy products was suspended by the business operator, and a review of practices was performed.

First complete genome sequence of Tenacibaculum maritimum serotype O4, a rising threat in marine aquaculture.

Tenacibaculum maritimum is a Gram-negative marine fish pathogen. Here, we present the complete genome sequence of strain SP9.1, representing the emerging serotype O4. Selected as a model for pathogenesis studies, this genome provides valuable insights into the genetic basis of virulence and adaptation, complementing existing data for serotype O1.

Klebsiella pneumoniae Glycoconjugate Vaccine Leads Based on Semi-Synthetic O1 and O2ac Antigens.

Klebsiella pneumoniae (KP) is a common opportunistic pathogen that emerged as a new critical threat to human health, due to its hypervirulence and widespread resistance against many antibiotics, including carbapenems. Alternative intervention strategies such as vaccines are not available. Cell-surface lipopolysaccharides (LPS) and capsular polysaccharides (CPS) are attractive targets for vaccine development. We present a method to synthesize LPS substructures, covering over 70% of virulent KP strains that were used to characterize the antibody repertoire of infected patients. Thereby, glycoconjugate vaccine leads against the Klebsiella pneumoniae serotypes O1, O2a, O2afg and O2ac have been identified.

Klebsiella pneumoniae Glycoconjugate Vaccine Leads Based on Semi‐Synthetic O1 and O2ac Antigens

Klebsiella pneumoniae (KP) is a common opportunistic pathogen that emerged as a new critical threat to human health, due to its hypervirulence and widespread resistance against many antibiotics, including carbapenems. Alternative intervention strategies such as vaccines are not available. Cell‐surface lipopolysaccharides (LPS) and capsular polysaccharides (CPS) are attractive targets for vaccine development. We present a method to synthesize LPS substructures, covering over 70% of virulent KP strains that were used to characterize the antibody repertoire of infected patients. Thereby, glycoconjugate vaccine leads against the Klebsiella pneumoniae serotypes O1, O2a, O2afg and O2ac have been identified.

Serotyping and Identification of Antimicrobial Resistance Genes in Avian Pathogenic Escherichia Coli Isolated from Poultry Flocks in Jiangxi Province, China.

Avian pathogenic Escherichia coli (APEC) is an important bacterial pathogen that causes severe respiratory and systemic infections in poultry. Our previous research investigated the prevalence and antimicrobial resistance phenotypes of APEC isolated from poultry flocks in Jiangxi Province, China. The present study aims to further identify the serotypes and the carbapenem-resistant gene blaNDM in APEC strains. Serotype investigations revealed that the most dominant serotype was O24 (53.2%), followed by O78 (11.9%), O2 (3.2%), O18 (2.4%), O45 (0.8%), and O88 (0.8%). Serotypes O1, O30, and O65 were not detected, and 35 strains (27.8%) were un-typed. The identified genes blaNDM-5 and blaNDM-1 shared a close phylogenetic distance with Klebsiella sp. and Acinetobacter sp. isolated from river and human feces, respectively. Two APEC strains carrying blaNDM-5 and blaNDM-1 were subjected to whole-genome sequencing and analysis. The results showed that blaNDM-5 was associated with the mobile genetic element IS5 and blaNDM-1 was associated with the mobile genetic element ISAba125. Current study findings can be helpful for effective vaccine development and provide a deep understanding of APEC infections and antimicrobial resistance in poultry flocks.

Serotype switching in Pseudomonas aeruginosa ST111 enhances adhesion and virulence.

Evolution of the highly successful and multidrug resistant clone ST111 in Pseudomonas aeruginosa involves serotype switching from O-antigen O4 to O12. How expression of a different O-antigen serotype alters pathogen physiology to enable global dissemination of this high-risk clone-type is not understood. Here, we engineered isogenic laboratory and clinical P. aeruginosa strains that express the different O-antigen gene clusters to assess the correlation of structural differences of O4 and O12 O-antigens to pathogen-relevant phenotypic traits. We show that serotype O12 is associated with enhanced adhesion, type IV pili dependent twitching motility, and tolerance to host defense molecules and serum. Moreover, we find that serotype O4 is less virulent compared to O12 in an acute murine pneumonia infection in terms of both colonization and survival rate. Finally, we find that these O-antigen effects may be explained by specific biophysical properties of the serotype repeat unit found in O4 and O12, and by differences in membrane stability between O4 and O12 expressing cells. The results demonstrate that differences in O-antigen sugar composition can affect P. aeruginosa pathogenicity traits, and provide a better understanding of the potential selective advantages that underlie serotype switching and emergence of serotype O12 ST111.

Synthesis of methylphosphorylated oligomannosides structurally related to lipopolisaccharide O-antigens of <i>Klebsiella pneumoniae</i> serotype O3 and the study of their immunologic properties

Synthesis of methylphosphorylated oligomannosides structurally related to lipopolisaccharide O-antigens of <i>Klebsiella pneumoniae</i> serotype O3 and the study of their immunologic properties

Limited Experimental Susceptibility of Post-Smolt Atlantic salmon (Salmo salar) to an Emergent Strain of Vibrio Anguillarum Serotype O3

Preliminary evidence has showed an emergent serotype O3 (SO3) strain of Vibrio anguillarum to cause mortality in pre-smolt Atlantic salmon (Salmo salar) by injection with >105 colony forming units (cfus). Here, we sought to identify the susceptibility of Atlantic salmon post-smolts to this emergent strain by both injection and cohabitation to better understand transmission risk within cultured salmon and possibly between salmon and Atlantic menhaden (Brevoortia tyrannus), where this strain was identified. We identified that although mortality could be induced with a high-dose (>106 cfus) intraperitoneal injection of the emergent SO3 strain (cumulative mortality of 40%), post-smolt Atlantic salmon were highly refractory to a low dose (<106 cfus; cumulative mortality of 3%) or cohabitation exposure (no mortality). A qPCR assay targeting this strain was developed and analytically validated, revealing the limited presence of bacterial DNA in the spleen of low-dose-injected fish (2/36) and no detections in sampled cohabitants (0/70) across three timepoints during the 27-day challenge. These results suggest that although Atlantic salmon can succumb to high-dose artificial infections with V. anguillarum SO3, the risk of natural transmissibility and susceptibility of Atlantic salmon to this emergent strain is anticipated to be low.

Genotypic analysis of Shiga toxin-producing Escherichia coli clonal complex 17 in England and Wales, 2014-2022.

Introduction. Shiga toxin-producing Escherichia coli (STEC) are zoonotic, gastrointestinal pathogens characterized by the presence of the Shiga toxin (stx) gene. Historically, STEC O157:H7 clonal complex (CC) 11 has been the most clinically significant serotype; however, recently there has been an increase in non-O157 STEC serotypes, including STEC O103:H2 belonging to CC17.Gap statement. STEC O103:H2 is an STEC serotype frequently isolated in England, although little is known about the epidemiology, clinical significance, associated public health burden or evolutionary context of this strain.Aim. Surveillance data and whole-genome sequencing data were analysed to determine the microbiological characteristics and public health burden of CC17, including the clinically significant serotype O103:H2, in England and Wales.Methodology. Isolates of E. coli belonging to CC17 (n=425) submitted to the Gastrointestinal Bacteria Reference Unit from 2014 to 2022 were whole genome sequenced, integrated with enhanced surveillance questionnaire data and analysed retrospectively.Results. Overall, diagnoses of CC17 infection increased every year since 2014. Most cases were female (58.5%), with the highest proportion of cases belonging to the 0-4 age group (n=83/424, 19.6%). Clinical presentation data identified diarrhoea (92.1%), abdominal pain (72.4%) and blood in stool (55.3%) as the most frequent symptoms, while 20.4% cases were admitted to hospital and 1.3% developed haemolytic uraemic syndrome. The five most common established serotypes were O103:H2 (64.5%), O123:H2 (11.1%), O151:H2 (6.6%), O71:H2 (3.3%) and O4:H2 (2.6%). The majority of CC17 isolates (78.6%) had the stx1a/eae virulence gene combination. Nine outbreak clusters of STEC infections that were mainly geographically dispersed and temporally related were identified and associated with foodborne transmission.Conclusions. Nationwide implementation of PCR to detect non-O157 STEC and improvements to algorithms for the follow-up of PCR-positive faecal specimens is recommended. Enhanced surveillance is necessary to assess the incidence of CC17 infection and overall burden of this CC within the UK population.

Characterization of novel sequence type 12531 and O8:H7 serotype carbapenem-resistant Escherichia coli with strong swimming and intestinal epithelial cell barrier migration abilities.

Carbapenem-resistant Enterobacteriaceae have become widely prevalent globally because of antibiotic misuse and the spread of drug-resistant plasmids, where carbapenem-resistant Escherichia coli (CREC) is one of the most common and prevalent pathogens. Furthermore, E. coli has been identified as a member of normal gut flora and does not cause disease under normal circumstances. However, certain strains of E. coli, due to the expression of virulence genes, can cause severe intestinal and extra-intestinal infections. Therefore, clinically, drug resistance and pathogenic E. coli strains are significantly challenging to treat. In this study, a novel CREC strain DC8855 was isolated from the ascites of a patient with intestinal perforation, identified as a novel sequence type 12531 (ST12531) and an unreported serotype O8:H7. It was revealed that the resistance of ST12531 CREC was predominantly conferred by an IncFII(K) plasmid carrying blaNDM-4. Furthermore, phylogenetic analysis indicated that this is the first discovery of such plasmids in China and the first identification in E. coli. Moreover, regarding virulence, the swimming assays, qRT-PCR, and in vitro intestinal barrier model indicated that DC8855 had significantly higher motility, flagella gene expression, and intestinal epithelial cell barrier migration ability than the other sequence types CREC strains (ST167 and ST410). In conclusion, this study identified novel CREC which was multidrug resistant as well as enteropathogenic and therefore requires continuous monitoring.

A cynomolgus monkey E. coli urinary tract infection model confirms efficacy of new FimH vaccine candidates.

The increase in urinary tract infections (UTI) caused by antibiotic-resistant Escherichia coli requires the development of new therapeutic agents and prophylactic vaccines. To evaluate the efficacy of new lead candidates, we implemented a cynomolgus macaque UTI challenge model that mimics human uncomplicated cystitis in response to transurethral challenge with a multidrug-resistant (MDR) E. coli serotype O25b ST131 isolate. E. coli fimbrial adhesin FimH and O-antigens are separately under clinical evaluation by others as vaccine candidates to prevent UTI and invasive urosepsis disease, respectively. Accordingly, we assessed the protective efficacy of three 50-µg intramuscular doses of a novel recombinant FimH antigen adjuvanted with liposomal QS21/MPLA compared with saline placebo in groups of nine animals. A third group was vaccinated with this FimH formulation in combination with 1 µg each of a four-valent mixture of serotype O1a, O2, O6, and O25b O-antigen CRM197 lattice glycoconjugates. Both vaccines elicited high levels of serum FimH IgG and adhesin blocking antibodies at the time of bacterial challenge and, for the combination group, O-antigen-specific antibodies. Following bacterial challenge, both vaccinated groups showed >200- and >700-fold reduction in bacteriuria at day 2 and day 7 post-infection compared with placebo, respectively. In parallel, both vaccines significantly reduced levels of inflammatory biomarkers IL-8 and myeloperoxidase in the urine at day 2 post-infection relative to placebo. Results provide preclinical proof-of-concept for the prevention of an MDR UTI infection by these new vaccine formulations.

Characterising virulence in a nontoxigenic non-O1/non-O139 Vibrio cholerae isolate imported from Vietnam

Vibrio cholerae is a major human pathogen that can cause life-threatening acute diarrhea. V. cholerae are classified according to O-antigen polysaccharide outer membrane properties, where the serotypes O1 and O139 are strains that cause pandemics and epidemics while non-O1/non-O139 usually cause mild disease. The dynamic evolution of V. cholerae involves acquisition of new virulence factors through horizontal gene transfer and formerly nontoxigenic serogroups are increasingly being reported to cause severe forms of human disease.In this study we have serotyped one isolate (ST588-CPH) of imported V. cholerae from Vietnam to Denmark and performed whole genome sequencing to identify known virulence genes and furthermore studied the pattern of virulence in closely related pathogenic strains of V. cholerae.ST558-CPH was found to be a non-O1/non-O139 strain. Initial analysis from the whole genome sequencing gave a 96,6 % match to the O139-specific wbfZ gene, but in a second analysis with a higher identification threshold, the wbfZ gene was absent. We suggest a “de novo” display of a database misannotation, which explains the conflicting results. The MLST analysis revealed that the isolate belongs to the nontoxigenic non-O1/non-O139 sequence type ST558. ST558 has recently been reported as a sequence type forming a cluster of ST's that should be monitored, as it has shown to have virulence causing moderate to severe illness. Our analysis of virulence genes identified MakA, a recently discovered toxin, which seems to be generally present in both toxigenic and nontoxigenic strains.

Positive assessment of an autogenous vaccine against pathogenic Escherichia coli in broiler breeders and their progeny in Morocco

Excessive use of antibiotics to control colibacillosis on poultry farms in Morocco contributes to the development of multiresistant avian pathogenic Escherichia coli. Autogenous vaccines are an alternative to antibiotic usage. The main goal of this study was to assess the efficacy of this approach to control recurrent outbreaks of colibacillosis in a large broiler production flow. A tetravalent autogenous vaccine (serotypes O78, O88, O91, and O185) was produced from multiresistant E. coli strains isolated from clinical lesions in breeding hens and used on two farms (65,000 breeding hens in total). On each farm, contemporaneous groups were included: groups vaccinated twice (12 and 18 weeks of age) and unvaccinated control groups. The performances of these flocks, as well as the performances of broilers hatched from these breeders (12 farms, over 600,000 broilers in total), were recorded. A significant reduction in lesion scores, mortality rate and a significant increase in the number of sellable day-old chicks were observed among vaccinated hens. In broilers, body weight at slaughter, lesion scores, feed conversion ratio, mortality, and condemnation rates were significantly improved. This is the first field observation of a lasting effect of breeder hen’s immunization with an autogenous vaccine against E. coli on their offspring.

Priority order of neonatal colonization by a probiotic or pathogenic Escherichia coli strain dictates the host response to experimental colitis.

The alarming prevalence of inflammatory bowel disease (IBD) in early childhood is associated with imbalances in the microbiome, the immune response, and environmental factors. Some pathogenic Escherichia coli (E. coli) strains have been found in IBD patients, where they may influence disease progression. Therefore, the discovery of new harmful bacterial strains that have the potential to drive the inflammatory response is of great importance. In this study, we compared the immunomodulatory properties of two E. coli strains of serotype O6: the probiotic E. coli Nissle 1917 and the uropathogenic E. coli O6:K13:H1. Using the epithelial Caco-2 cell line, we investigated the different abilities of the strains to adhere to and invade epithelial cells. We confirmed the potential of E. coli Nissle 1917 to modulate the Th1 immune response in a specific manner in an in vitro setting by stimulating mouse bone marrow-derived dendritic cells (BM-DCs). In gnotobiotic in vivo experiments, we demonstrated that neonatal colonization with E. coli Nissle 1917 achieves a stable high concentration in the intestine and protects mice from the progressive effect of E. coli O6:K13:H1 in developing ulcerative colitis in an experimental model. In contrast, a single-dose treatment with E. coli Nissle 1917 is ineffective in achieving such high concentrations and does not protect against DSS-induced ulcerative colitis in mice neonatally colonized with pathobiont E. coli O6:K13:H1. Despite the stable coexistence of both E. coli strains in the intestinal environment of the mice, we demonstrated a beneficial competitive interaction between the early colonizing E. coli Nissle 1917 and the late-arriving strain O6:K13:H1, suggesting its anti-inflammatory potential for the host. This study highlights the importance of the sequence of bacterial colonization, which influences the development of the immune response in the host gut and potentially impacts future quality of life.

Induction and comparative resuscitation of viable but nonculturable state on Vibrio parahaemolyticus serotypes O3:K6 and O1:K25.

Vibrio parahaemolyticus, an important food-borne pathogens found to be associated with seafoods and marine environs. It has been a topic of debate for many decades that most pathogens are known to enter a viable but nonculturable (VBNC) state under cold temperature and nutrient limited conditions. The present study examined the time required for the induction of VBNC state and the revival strategies of both the endemic O3:K6 and O1:K25 sporadic strains of V. parahaemolyticus. The results revealed that V. parahaemolyticus survived even after 55 days of incubation in nutrient starved media such as phosphate buffered saline (PBS) and Coastal Water (CW) and could be recovered by temperature upshift method, and compared the resuscitation using Dulbecco's Modified Eagle Medium (DMEM), sheep blood serum, chitin flakes with live Artemia salina, and the results suggests that chitin plays a significant role in regulating the VBNC state. It was also confirmed by Confocal Laser Scanning Microscopy (CLSM) and Scanning Electron Microscope (SEM) analysis that VBNC cells can alter their morphology to coccoid forms in order to survive in most extreme nutrient limited environment. Further data on the promoting factors and the exact mechanism that resuscitate VBNC V. parahaemolyticus in cold natural environments and frozen foods are needed to perform a robust risk assessment.

Comparative genomics of Tn6411 transposons carrying the blaIMP-1 gene in Pseudomonas aeruginosa.

We aimed to determine the molecular characteristics of carbapenem-resistant Pseudomonas aeruginosa strains 18081308 and 18083286, which were isolated from the urine and the sputum of two Chinese patients, respectively. Additionally, we conducted a comparative analysis between Tn6411 carrying blaIMP-1 in strain 18083286 and transposons from the same family available in GenBank. Bacterial genome sequencing was carried out on strains 18081308 and 18083286 to obtain their whole genome sequence. Average nucleotide identity (ANI) was used for their precise species identification. Serotyping and multilocus sequence typing were performed. Furthermore, the acquired drug resistance genes of these strains were identified. The carbapenem-resistant P. aeruginosa strains isolated in the present study were of sequence type ST865 and serotype O6. They all carried the same resistance genes (aacC2, tmrB, and blaIMP-1). Tn6411, a Tn7-like transposon carrying blaIMP-1, was found in strain 18083286 by single molecule real time (SMRT) sequencing. We also identified the presence of this transposon sequence in other chromosomes of P. aeruginosa and plasmids carried by Acinetobacter spp. in GenBank, indicating the necessity for heightening attention to the potential transferability of this transposon.

Complete genome sequence of Vibrio parahaemolyticus ST36 strain MAVP-26, a clinical isolate from an oyster-borne human gastric infection.

A Pacific native lineage of Vibrio parahaemolyticus ST36 serotype O4:K12 was introduced into the Atlantic, which increased local source illnesses. To identify genetic determinants of virulence and ecological resiliency and track their transfer into endemic populations, we constructed a complete genome of a 2013 Atlantic-traced clinical isolate by hybrid assembly.

Klebsiella pneumoniae O-polysaccharide biosynthesis highlights the diverse organization of catalytic modules in ABC transporter-dependent glycan assembly

Klebsiella pneumoniae provides influential prototypes for lipopolysaccharide O antigen (OPS) biosynthesis in Gram-negative bacteria. Sequences of OPS-biosynthesis gene clusters in serotypes O4 and O7 suggest fundamental differences in the organization of required enzyme modules compared to other serotypes. Furthermore, some required activities were not assigned by homology shared with characterized enzymes. The goal of this study was therefore to resolve the serotype O4 and O7 pathways, to expand our broader understanding of glycan polymerization and chain termination processes. The O4 and O7 antigens were produced from cloned genetic loci in recombinant Escherichia coli. Systematic in vivo and in vitro approaches were then applied to assign each enzyme in each of the pathways, defining the necessary components for polymerization and chain termination. OPS assembly is accomplished by multiprotein complexes formed by interactions between polymerase components variably distributed in single and multi-module proteins. In each complex, a terminator function is present in a protein containing a characteristic coiled-coil molecular ruler, which determines glycan chain-length. In serotype O4, we discovered a CMP-α-3-deoxy-ᴅ-manno-octulosonic acid (Kdo)-dependent chain-terminating glycosyltransferase that is the founding member of a new glycosyltransferase family (GT137), and potentially identifies a new glycosyltransferase fold. The O7 OPS is terminated by a methylphosphate moiety, like the K. pneumoniae O3 antigen, but the methyltransferase-kinase enzyme pairs responsible for termination in these serotypes differ in sequence and predicted structures. Together, the characterization of O4 and O7 has established unique enzyme activities and provided new insight into glycan-assembly strategies that are widely distributed in bacteria.

Microbial landscape in acute purulent-catarrhal postpartum endometritis in cows

A special place among environmental factors affecting the body of animals is occupied by microorganisms— pathogens of infectious diseases. In this regard, the problem of circulation of associations of conditionally pathogenic microorganisms capable of causing a fairly wide range of pathologies in cattle in cattle is acute. The article provides a study of the microbial background of the vaginal-luminous contents selected in the acute purulent-catarrhal postpartum endomethry in cows. It was shown that 58 strains of opportunistic microorganisms of 13 species, classified into 6 genera, were isolated from 20 cows suffering from acute purulent catarrhal endometritis. The most frequently isolated cultures were St. aureus, E. coli (serotypes O4, O9 and O83), Str. pyogenes, Str. agalactiae, P. aeruginosa, Str. uberis and Str. faecalis. Moreover, the development of acute purulent-catarrhal endometritis in cows was more often caused by grampositive bacteria. Of the 58 isolated strains of microorganisms, 22 (37.9%) cultures caused the death of white mice when administered intraperitoneally. At the same time, gram-positive cocci were more likely to have pathogenic properties, namely representatives of the genera Streptococcus spp. (11 — 50.0%) and Staphylococcus spp. (6 — 27.3%) isolates, respectively. It was found that endometritis more often causes associations of opportunistic microorganisms, which included three joints in 14 (50.0%) cases, less often four joints in 7 (25.0%) cases. The isolated microorganisms were sensitive to only three antibacterial drugs: cefkin, cefepime and marbofloxacin.