Incidence of virulence determinants in clinical Enterococcus faecalis and Enterococcus faecium isolates collected in Bulgaria

Species prevalence, virulence genes, and antibiotic resistance of enterococci from food-producing animals at a slaughterhouse in Turkey

Healthy cattle, sheep, and goats can be reservoirs for gastrointestinal pathogenic fecal enterococci, some of which could be multidrug-resistant to antimicrobials. The objective of this study was to determine the prevalence and diversity of Enterococcus species in healthy sheep, goat, and cattle carcasses, as well as to analyze the antimicrobial resistance phenotype/genotype and the virulence gene content. During 2019-2020, carcass surface samples were collected from 150 ruminants in a slaughterhouse. A total of 90 enterococci, comprising five species, were obtained. The overall prevalence of enterococci was found to be 60%, out of which 37.7% were identified as Enterococcus (E.) hirae, 33.3% as E. casseliflavus, 15.5% as E. faecium, 12.2% as E. faecalis, and 1.1% as E. gallinarum. Virulence-associated genes of efaA (12.2%) were commonly observed in the Enterococcus isolates, followed by gelE (3.3%), asaI (3.3%), and ace (2.2%). High resistance to quinupristin-dalfopristin (28.8%), tetracycline (21.1%), ampicillin (20%), and rifampin (15.5%) was found in two, four, four, and five of the Enterococcus species group, respectively. The resistance of Enterococcus isolates to 11 antibiotic groups was determined and multidrug resistant (MDR) strains were found in 18.8% of Enterococcus isolates. Characteristic resistance genes were identified by PCR with an incidence of 6.6%, 2.2%, 1.1%, 1.1%, 1.1%, and 1.1% for the tetM, ermB, ermA, aac(6')Ie-aph(2")-la, VanC1, and VanC2 genes in Enterococcus isolates, respectively. Efflux pump genes causing multidrug resistance were detected in Enterococcus isolates (34.4%). The results showed that there were enterococci in the slaughterhouse with a number of genes linked to virulence that could be harmful to human health.

The Impact of Enterococcus spp. in the Immunocompromised Host: A Comprehensive Review

The immunocompromised host is usually vulnerable to infectious diseases due to broad-spectrum treatments and immunological dysregulation. The Enterococcus genus consists of normal gut commensals, which acquire a leading role in infective processes among individuals with compromised immune systems. These microorganisms may express a potential virulence and resistance spectrum, enabling their function as severe pathogens. The Enterococcus spp. infections in immunocompromised hosts appear to be difficult to resolve due to the immunological response impairment and the possibility of facing antimicrobial-resistant strains. As regards the related risk factors, several data demonstrated that prior antibiotic exposure, medical device insertion, prolonged hospitalization and surgical interventions may lead to Enterococcus overgrowth, antibiotic resistance and spread among critical healthcare settings. Herein, we present a comprehensive review of Enterococcus spp. in the immunocompromised host, summarizing the available knowledge about virulence factors, antimicrobial-resistance mechanisms and host-pathogen interaction. The review ultimately yearns for more substantial support to further investigations about enterococcal infections and immunocompromised host response.

Antibiotic Resistance Characterization and Molecular Characteristics of Enterococcus Species Isolated from Combination Probiotic Preparations in China

Enterococci can act as reservoirs for antibiotic-resistant genes that are potentially at risk of being transferred to other bacteria that inhabit in the gastrointestinal tract. The aim of this study was to determine the phenotypic and molecular characteristics of antibiotic-resistant enterococci isolated from probiotic preparations. In total, we isolated 15 suspected Enterococcus species from 5 compound probiotics, which were identified by 16S rDNA as 12 Enterococcus faecium and 3 Enterococcus faecalis. Determination of antimicrobial susceptibility by the microdilution broth method showed widespread resistance to sulfamethoxazole (100%), norfloxacin (99.3%), azithromycin (99.3%), gentamicin (86.7%), and chloramphenicol (20%). Whole genome sequencing of five resistant strains revealed that all had circular DNA chromosomes and that E. faecium J-1-A to J-4-A contained a plasmid, while E. faecalis J-5-A did not. The results of the resistance gene analysis revealed that each strain contained approximately 30 resistance genes, with the antibiotic resistance genes and the multidrug resistance efflux pump genes mdtG, lmrC, and lmrD detected in all strains. The chloramphenicol resistance genes ykkC and ykkD were first identified in E. faecalis. And there were 21, 19, 21, 21, and 29 virulence factors involved in strains, respectively. Further analysis of the gene islands (GIs) revealed that each strain contained more than 10 GIs. The above results confirm the existence of hidden dangers in the safety of probiotics and remind us to carefully select probiotic preparations containing enterococcal strains to avoid the potential spread of resistance and pathogenicity.

Comparative study of virulence factor genes, β-hemolysis and biofilm production in invasive and colonizing enterococci

Objectives: In humans, enterococci are among the most important opportunistic pathogens. This study aims to compare invasive isolates obtained from blood cultures of patients with sepsis and endocarditis with colonizing isolates obtained from healthy donors’ stool samples.

Methods: A case-by-case assessment was conducted on invasive infection cases to determine whether enterococci were involved in their pathogenesis. They were tested for the presence of virulence factor genes, β-hemolysis on agars supplemented with human and sheep blood, and biofilm forming capacity.

Results: Three species of enterococci were identified among invasive isolates: Enterococcus faecalis, Enterococcus faecium, and Enterococcus durans. All endocarditis isolates were biofilm producers. Genes esp, gelE, asa1, ace, hyl, cylB, and cylA were present in 7 (41.2%), 11 (64.7%), 11 (64.7%), 13 (76.5%), 0, 3 (17.6%), and 1 (5.9%) invasive isolate, but none of them could be linked to a particular infection (sepsis or endocarditis). Colonizing isolates proved to have had more virulence factor genes, but the differences were not statistically significant. Members of that group produced a greater amount of biofilm when the ace gene was absent ( p = 0.047). The production of β-hemolysis by noninvasive strains was detected more frequently when agar was supplemented with human blood ( p = 0.021). In general, the presence of either cyl gene on that specific agar was in direct connection with the production of β-hemolysis: cylA ( p = 0.047) or cylB ( p = 0.020).

Conclusion: We have been unable to establish any correlation between invasive isolates and any virulence gene carriage and biofilm formation. β-hemolysis was produced significantly more often by colonizing strains when agar had been supplemented with human blood.

Antibiotic resistance and virulence potentials of E. faecalis and E. faecium in hospital wastewater: a case study in Ardabil, Iran

Hospital wastewater can contaminate the environment with antibiotic-resistant and virulent bacteria. We analyzed wastewater samples from four hospitals in Ardabil province, Iran for Enterococcus faecium and Enterococcus faecalis using culture and molecular methods. We also performed antimicrobial susceptibility testing and polymerase chain reaction testing for resistance and virulence genes. Out of 141 enterococci isolates, 68.8% were E. faecium and 23.4% were E. faecalis. Ciprofloxacin and rifampicin showed the highest level of resistance against E. faecalis and E. faecium isolates at 65%. High-level gentamicin resistance (HLGR), high-level streptomycin resistance (HLSR), ampicillin, and vancomycin resistance were observed in 25, 5, 10, and 5.15% of E. faecium, and 15, 6, 15, and 3.03% of E. faecalis isolates, respectively. The ant(6')-Ia and ant(3')-Ia genes that were responsible for streptomycin resistance were observed in HLSR isolates and aph(3')-IIIa and aac(6') Ie-aph(2″)-Ia genes accounting for gentamicin resistance were detected in HLGR isolates. vanA was the predominant gene detected in vancomycin-resistant isolates. The majority of isolates were positive for gelE, asa1, esp, cylA, and hyl virulence genes. We found that drug-resistant and virulent E. faecalis and E. faecium isolates were prevalent in hospital wastewater. Proper treatment strategies are required to prevent their dissemination into the environment.

Revisiting ESKAPE Pathogens: virulence, resistance, and combating strategies focusing on quorum sensing

The human-bacterial association is long-known and well-established in terms of both augmentations of human health and attenuation. However, the growing incidents of nosocomial infections caused by the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter sp.) call for a much deeper understanding of these organisms. Adopting a holistic approach that includes the science of infection and the recent advancements in preventing and treating infections is imperative in designing novel intervention strategies against ESKAPE pathogens. In this regard, this review captures the ingenious strategies commissioned by these master players, which are teamed up against the defenses of the human team, that are equally, if not more, versatile and potent through an analogy. We have taken a basketball match as our analogy, dividing the human and bacterial species into two teams playing with the ball of health. Through this analogy, we make the concept of infectious biology more accessible.

Analysis of Antibiotic-Resistant and Virulence Genes of Enterococcus Detected in Calf Colostrum-One Health Perspective

Enterococci are considered among the most prevalent global multidrug-resistant microorganisms globally. Their dissemination is a global concern, particularly by food-producing animals for both animals and humans. The aim of this study was to identify the species and investigate the antibiotic resistance and virulence profile of Enterococcus in bovine colostrum. Out of 88 presumptive Enterococcus isolates, species identification and susceptibility to 14 antimicrobials were tested using the disk diffusion method. An analysis of the antibiotic resistance and virulence genes was performed on the most prevalent species, using specific PCR assays. Enterococcus faecalis (54.5%), E. faecium (14.8%) and E. gallinarum (6.8%) were the identified species. To the best of our knowledge, this is the first report of E. gallinarum in bovine colostrum. The majority of the isolates showed resistance to quinupristin-dalfopristin (95.9%), erythromycin (80.7%), tetracycline (80.7%) and streptomycin (58%). Ninety-two percent of isolates were classified as multidrug-resistant. The most frequently detected resistance genes were tet(K) (61.1%), tet(M) (75.9%), tet(L) (90.7%), erm(B) (55.6%) and ant(6)-Ia (46.3%). The most prevalent virulence factors were cpd, esp, agg and cylL_L. Enterococcus faecium showed a higher probability of carrying the erm(C), tet(M), ace and gel(E) genes (p < 0.05). These results demonstrated that colostrum can constitute an important reservoir and vehicle for the dissemination of antibiotic resistance and virulence genes to the three niches included in a One Health perspective (humans, animals and the environment), highlighting the importance of hygiene sanitary measures to mitigate colostrum microbial contamination.

Antibiotic Resistance of Enterococcus Species in Ornamental Animal Feed

Enterococcus is a bacterial genus that is strongly associated with nosocomial infections and has a high capacity to transfer and acquire resistance genes. In this study, the main objective was to evaluate the presence of Enterococcus species in ornamental animal feed and characterize their antimicrobial resistance and virulence factors. Antimicrobial susceptibility was determined using 14 antimicrobial agents by the disk diffusion method, complemented by genotypic analysis to identify Enterococcus species and the presence of 14 antimicrobial resistance and 10 virulence genes. From 57 samples of ornamental animal feed, 103 Enterococcus isolates were recovered from 15 bird, 9 fish and 4 reptile feed samples. Enterococcus isolates were highly resistance to rifampicin (78%) and erythromycin (48%), and 48% of isolates were classified as multidrug-resistant. Enterococcus faecalis (36.7%) and E. faecium (31.7%) were the species most frequently identified. Most isolates carried the resistance genes ermB (57%) and tetL (52%) and the virulence genes, cylL (52%) and esp (40%). Enterococcus gallinarum was the species with the highest number of multidrug-resistant isolates (50%) and virulence genes (80%). These results highlight the high levels of antibiotic-resistant Enterococcus spp. present in ornamental animal feed and the growing interaction of these animals with humans as a public health concern.

Prevalence of Genes Encoding Resistance to Aminoglycosides and Virulence Factors Among Intestinal Vancomycin-Resistant Enterococci

Background: Vancomycin-resistant enterococci (VRE) are recognized as nosocomial pathogens with increased importance in recent years. These bacteria are frequently isolated from patients admitted to intensive care units (ICUs). Enterococcal pathogenicity is enhanced by different antibiotic resistance and virulence determinants. Objectives: The present study aimed to assess the prevalence of genes encoding resistance to antibiotics and virulence factors in intestinal VRE isolates from ICU patients. Methods: In this study, 23 VREs were investigated. Minimum inhibitory concentrations (MICs) to nine antimicrobial agents were examined using E-test. Genes encoding vancomycin resistance (vanABCDMN), aminoglycoside-modifying enzymes (aac(6')-Ie-aph(2")-Ia, aph(2")-Ib, aph(2")-Ic, aph(2")-Id, aph(3')-IIIa, ant(3')-Ia, ant(4')-Ia, ant(6')-Ia), together with genes for various virulence factor (ace/acm, asa1, cylA, efaA, esp, gelE and hyl), were detected using multiplex PCR. Results: The species distribution of the tested VRE was as follows: Nine Enterococcus casseliflavus, seven E. gallinarum, and seven E. faecium. The vanA gene was found in all E. faecium, in six of which the classical VanA phenotype was observed. The vancomycin (vanC) phenotype was associated with the presence of vanC1 gene in E. gallinarum and the vanC2 gene in E. casseliflavus isolates. The aac(6')-Ie-aph(2")-Ia gene was encoding high-level gentamicin resistance (HLGR) in the studied VRE. All E. faecium were positive for acm and esp, while acm in combination with esp or hyl was detected in 2 vanC enterococci. Conclusions: According to the findings, there was a correlation between the phenotype and the genotype of glycopeptide resistance in the tested VRE. HLGR was more prevalent in E. faecium because of the presence of aac(6')-Ie-aph(2")-Ia. The higher prevalence of virulence determinants was confirmed in vanA isolates compared to the studied vanC-carrying enterococci.

Genomic insights into antibiotic-resistance and virulence genes of Enterococcus faecium strains from the gut of Apis mellifera

Enterococcus faecium is a lactic acid bacterium that confers beneficial health effects in humans. However, lately, a number of E. faecium strains have been linked to the spread of nosocomial infections in the hospital environment. Therefore, any potential commercial usage of E. faecium isolates should be preceded by an assessment of infection risk. In the current study, the genomes of two novel E. faecium strains Am1 (larval isolate) and Bee9 (adult bee isolate) isolated from the gut of Apis mellifera L. (honeybee) were sequenced to allow evaluation of their safety. In particular, their genomes were screened for antibiotic-resistance and virulence genes. In addition, their potential to spread resistance in the environment was evaluated. The analysis revealed that Am1 and Bee9 possess 2832 and 2844 protein-encoding genes, respectively. In each case, the genome size was 2.7 Mb with a G+C content of 37.9 mol%. Comparative analysis with probiotic, non-pathogenic and pathogenic enterococci revealed that there are variations between the two bee E. faecium isolates and pathogenic genomes. They were, however, closely linked to the probiotic comparison strains. Phenotypically, the Am1 and Bee9 strains were susceptible to most antibiotics tested, but showed intermediate sensitivity towards erythromycin, linezolid and trimethoprim/sulfamethoxazole. Notably, no genes associated with antibiotic resistance in clinical isolates (e.g. vancomycin resistance: vanA, vanB, vanS, vanX and vanY) were present. In addition, the insertion sequences (IS16, ISEfa11 and ISEfa5), acting as molecular pathogenicity markers in clinically relevant E. faecium strains, were also absent. Moreover, the analysis revealed the absence of three key pathogenicity-associated genes (acm, sgrA, ecbA) in the Am1 and Bee9 strains that are found in the prominent clinical isolates DO, V1836, Aus0004 and Aus0085. Overall, the findings of this investigation suggest that the E. faecium isolates from the bee gut have not suffered any recent clinically relevant antibiotic exposure. It also suggests that E. faecium Am1 and Bee9 are safe potential probiotic strains, because they lack the phenotypic and genetic features associated with strains eliciting nosocomial infections.

Enterococcus faecalis Shields Porphyromonas gingivalis in Dual-Species Biofilm in Oxic Condition

Aim: To develop a reproducible biofilm model consisting of Enterococcus faecalis (E. faecalis) and Porphyromonas gingivalis (P. gingivalis) and to evaluate the interaction between the two bacterial species. Methodology: E. faecalis and P. gingivalis were grown in mono-culture, sequential, and co-culture models for 96 h in a 96-well polystyrene microtiter plate under both aerobic and anaerobic conditions separately. The viability of the two bacterial species in the biofilms was quantified by polymerase chain reaction (qPCR). Biofilm thickness and protein contents were measured using confocal laser scanning microscopy (CLSM). Two-way analysis of variance (ANOVA) was performed to analyze cell viability and biofilm thickness among different culture models cultivated under either aerobic or anaerobic conditions. The level of significance was set at p < 0.05. Results: Different culture models tested did not show any significant difference between the viable cell counts of both E. faecalis and P. gingivalis cultivated under aerobic and anaerobic conditions (p > 0.05). Biofilm was significantly thicker (p < 0.05) in the co-culture models compared to the mono-culture and sequential models. Protein contents in the biofilms were more pronounced when both bacterial species were co-cultured under aerobic conditions. Conclusions: E. faecalis appeared to shield P. gingivalis and support its continued growth in oxic (aerobic) conditions. The co-culture model of E. faecalis and P. gingivalis produced a significantly thicker biofilm irrespective of the presence or absence of oxygen, while increased protein contents were only observed in the presence of oxygen.

Regulatory Effect of Lactiplantibacillus plantarum 2-33 on Intestinal Microbiota of Mice With Antibiotic-Associated Diarrhea

Diarrhea is one of the common adverse reactions in antibiotic treatment, which is usually caused by the imbalance of intestinal flora, and probiotics play an important role in the structure of intestinal flora. Therefore, this experiment studied the regulatory effect of Lactiplantibacillus plantarum 2-33 on antibiotic-associated diarrhea (AAD) mice. First, the AAD mice model was established by the mixed antibiotic solution of gentamicin sulfate and cefradine. Then, the physiological indexes and diarrhea of mice were observed and recorded by gastric perfusion of low dose (1.0 × 10⁷ CFU/ml), medium dose (1.0 × 10⁸CFU/ml), and high dose (1.0 × 10⁹ CFU/ml) strain 2-33. 16S rRNA gene V3-V4 regions were sequenced in colon contents of mice in control group, model group, self-healing group, and experimental group, respectively, and the diversity of intestinal flora and gene function prediction were analyzed. The results showed that the intestinal flora of AAD mice was not significantly regulated by gastric perfusion of strain 2-33 to 7 days, but the relative abundance and diversity of intestinal flora of AAD mice were significantly improved by gastric perfusion to 14 days (p < 0.05). In addition, at the genus level, the relative abundance of Lactobacillus increased significantly, and the relative abundance of Enterococcus and Bacillus decreased significantly (p < 0.05). In addition, the regulation of strain 2-33 on intestinal flora of AAD mice was time- and dose-dependent, short-term gastric perfusion, and low dose had no significant effect (p > 0.05). Strain 2-33 can significantly increase the levels of anti-inflammatory cytokines IL-4 and IL-10, significantly decrease the levels of proinflammatory cytokines TNF-α and IFN-γ (p < 0.05), and can also adjust carbohydrate metabolism, amino acid metabolism, and energy metabolism to normal levels, thus accelerating the recovery of intestinal flora structure of AAD mice. In summary, strain 2-33 can improve the structure and diversity of intestinal flora of AAD mice, balance the level of substance and energy metabolism, and play a positive role in relieving diarrhea, maintaining and improving the intestinal microecological balance.

Association between virulence factors and biofilm formation in Enterococcus faecalis isolated from semen of infertile men

PROBLEM

Enterococcus faecalis is a common microbial semen contaminant. Although virulence factors and biofilm formation have often been analyzed in Enterococcus spp., there is little information about these features in isolates obtained from the genitourinary tract. This study was intended to characterize and determine the relationship between biofilm-forming ability and the presence of E. faecalis virulence factors isolated from human semen.

METHOD OF STUDY

A total of 32 patients diagnosed with primary infertility and 28 healthy men were included in the study. Semen analyses were performed according to the WHO guidelines. PCR reactions were applied for the detection of ace, esp, efeA, gelE, asa1, and cylA genes. Microtiter plate assay, via measurement of OD_560, was used to measure the biofilm-forming ability of the isolates.

RESULTS

Sixty E. faecalis isolates from semen of infertile and fertile men were characterized by phenotypic and genotypic methods. The prevalence of ace, esp, efeA, gelE, asa1 and cylA were reported to be 81.3%/100.0%, 81.3%/89.3%, 81.3%/85.7%, 71.9%/53.6%, 8.8%/75.0%, and 62.5%/67.9% in infertile/fertile groups; respectively. Strong, weak, and non-biofilm reactions were reported to be 50.0%/21.4%, 40.6%/64.3%, and 9.4%/14.3% in infertile and fertile groups; respectively.

CONCLUSIONS

There was a significant relationship between fertility and weak biofilm reaction and also between biofilm formation and possession of the esp gene (P < .05). It could be speculated that colonization with E. faecalis with a strong ability for biofilm formation could become a potential threat to men's fertility.

High prevalence of vancomycin non-susceptible and multi-drug resistant enterococci in farmed animals and fresh retail meats in Bangladesh

The emergence of antimicrobial resistant Enterococcus spp., a main cause of untreatable nosocomial infection, in food animals and dissemination to humans is a public health risk. The study was performed to determine the prevalence and antimicrobial resistance, and virulence characteristics of Enterococcus faecalis and Enterococcus faecium in food animals and meats in Bangladesh. Enterococcus spp., were confirmed using sodA gene specific PCR, and antimicrobial resistance and virulence properties were characterized by PCR. Enterococcus spp. were recovered from 57% of the collected samples (n = 201/352). Farm samples yielded significantly higher (p ≤ 0.05) prevalence (62%) than that of retail meat samples (41%). E. faecalis (52%) is most frequently isolated species. Greater proportions of isolates exhibited resistance to tetracycline (74%), erythromycin (65%) and ciprofloxacin (34%). Fifty-one isolates are vancomycin non-susceptible enterococci (VNSE), of which forty-seven are MDR and twenty are linezolid resistant, a last line drug for VNSE. Virulence factors such as gelatinase (gelE), aggregation factor (asa1) and sex pheromone (cpd) are detected along with vancomycin resistance gene (vanA, vanB and vanC2/C3) in VNSE isolates. The high prevalence of MDR enterococci in food animals and retail meats may cause consumers infections with concomitant reduction of available therapeutic options.

Genomic Analysis of Multidrug-Resistant Enterococcus faecium Harboring vanA Gene from Wastewater Treatment Plants

The emergence of vancomycin-resistant Enterococcus faecium (Efm) harboring vanA gene and multidrug-resistant determinants is a relevant public health concern. It is an opportunistic pathogen responsible for nosocomial infections widely distributed in the environment, including wastewater treatment plants (WWTPs). Our study addresses a genomic investigation of vanA-carrying Efm from WWTPs in Brazil. Samples from five WWTPs supplied with sewage from different sources were evaluated. Here we present whole-genome sequencing of eight vanA-Efm isolates performed on Illumina MiSeq platform. All these isolates presented multidrug-resistant profile, and five strains were from treated wastewater. Multiple antimicrobial resistance genes (ARGs) were found, such as aph(3')-IIIa, ant(6')-Ia, erm(B), and msrC, some of them being allocated in plasmids. The virulence profile was predominantly constituted by efaAfm and acm genes and all isolates, except for one, were predicted as human pathogens. Multilocus sequence typing analysis revealed a new allele and five different STs, three previously described (ST32, ST168, and ST253) and two novel ones (ST1893 and ST1894). Six strains belonged to CC17, often associated with hospital outbreaks. As far as our knowledge, no genomic studies of vanA-Efm recovered from WWTPs revealed isolates belonging to CC17 in Brazil. Therefore, our findings point to the environmental spread of Efm carrying multiple ARGs.

Pharmacodynamics of Linezolid Plus Fosfomycin Against Vancomycin-Resistant Enterococcus faecium in a Hollow Fiber Infection Model

The optimal therapy for severe infections caused by vancomycin-resistant Enterococcus faecium (VREfm) remains unclear, but the combination of linezolid and fosfomycin may be a good choice. The 24-h static-concentration time-kill study (SCTK) was used to preliminarily explore the pharmacodynamics of linezolid combined with fosfomycin against three clinical isolates. Subsequently, a hollow-fibre infection model (HFIM) was used for the first time to further investigate the pharmacodynamic activity of the co-administration regimen against selected isolates over 72 h. To further quantify the relationship between fosfomycin resistance and bacterial virulence in VREfm, the Galleria mellonella infection model and virulence genes expression experiments were also performed. The results of SCTK showed that the combination of linezolid and fosfomycin had additive effect on all strains. In the HFIM, the dosage regimen of linezolid (12 mg/L, steady-state concentration) combined with fosfomycin (8 g administered intravenously every 8 h as a 1 h infusion) not only produced a sustained bactericidal effect of 3∼4 log₁₀ CFU/mL over 72 h, but also completely eradicated the resistant subpopulations. The expression of virulence genes was down-regulated to at least 0.222-fold in fosfomycin-resistant strains compared with baseline isolate, while survival rates of G. mellonella was increased (G. mellonella survival ≥45% at 72 h). For severe infections caused by VREfm, neither linezolid nor fosfomycin monotherapy regimens inhibited amplification of the resistant subpopulations, and the development of fosfomycin resistance was at the expense of the virulence of VREfm. The combination of linezolid with fosfomycin produced a sustained bactericidal effect and completely eradicated the resistant subpopulations. Linezolid plus Fosfomycin is a promising combination for therapy of severe infections caused by VREfm.

Characterizing Plasmids in Bacteria Species Relevant to Urinary Health

The urinary tract has a microbial community (the urinary microbiota or urobiota) that has been associated with human health. Whole genome sequencing of bacteria is a powerful tool, allowing investigation of the genomic content of the urobiota, also called the urinary microbiome (urobiome). Bacterial plasmids are a significant component of the urobiome yet are understudied. Because plasmids can be vectors and reservoirs for clinically relevant traits, they are important for urobiota dynamics and thus may have relevance to urinary health. In this project, we sought plasmids in 11 clinically relevant urinary species: Aerococcus urinae, Corynebacterium amycolatum, Enterococcus faecalis, Escherichia coli, Gardnerella vaginalis, Klebsiella pneumoniae, Lactobacillus gasseri, Lactobacillus jensenii, Staphylococcus epidermidis, Streptococcus anginosus, and Streptococcus mitis. We found evidence of plasmids in E. faecalis, E. coli, K. pneumoniae, S. epidermidis, and S. anginosus but insufficient evidence in other species sequenced thus far. Some identified plasmidic assemblies were predicted to have putative virulence and/or antibiotic resistance genes, although the majority of their annotated coding regions were of unknown predicted function. In this study, we report on plasmids from urinary species as a first step to understanding the role of plasmids in the bacterial urobiota. IMPORTANCE The microbial community of the urinary tract (urobiota) has been associated with human health. Whole genome sequencing of bacteria permits examination of urobiota genomes, including plasmids. Because plasmids are vectors and reservoirs for clinically relevant traits, they are important for urobiota dynamics and thus may have relevance to urinary health. Currently, urobiota plasmids are understudied. Here, we sought plasmids in 11 clinically relevant urinary species. We found evidence of plasmids in E. faecalis, E. coli, K. pneumoniae, S. epidermidis, and S. anginosus but insufficient evidence in the other 6 species. We identified putative virulence and/or antibiotic resistance genes in some of the plasmidic assemblies, but most of their annotated coding regions were of unknown function. This is a first step to understanding the role of plasmids in the bacterial urobiota.

Perfil epidemiológico de la infección por Enterococcus SPP en un hospital regional

Introducción: los enterococos son responsables de múltiples infecciones y por su creciente patrón de resistencia se ha vuelto de interés en el país y en el mundo. Objetivo: caracterizar las infecciones por Enterococcus spp. Metodología: estudio descriptivo, retrospectivo observacional transversal desde enero 2015 hasta enero 2018 en un hospital regional. Resultados: la prevalencia de las infecciones por Enterococcus spp. fue de 0,154%. El E. faecalis fue el más aislado, seguido del E. faecium. La resistencia a ampicilina fue de 19% y a vancomicina de 10%; 32% de los pacientes tuvieron terapia empírica con vancomicina y 22% con piperacilina tazobactam, la mediana de antibioticoterapia fue de 10 días. Discusión: el interés por los Enterococcus spp. se ha incrementado debido a que representan una carga importante en las infecciones asociadas con la atención en salud (IAAS). La mayoría se dan en hombres con una edad mediana de 40 a 60 años, hospitalizados en UCI, con infecciones urinarias y comorbilidades como inmunosupresión y cirugías previas. Conclusión: como ha venido reportándose aumento en las tasas de resistencia a vancomicina y ampicilina, se recomienda el uso responsable de la terapia antibiótica, con la finalidad de erradicar en forma eficaz al patógeno y prevenir nuevas resistencias.

Aggrandizement of fermented cucumber through the action of autochthonous probiotic cum starter strains of Lactiplantibacillus plantarum and Pediococcus pentosaceus

Purpose

Cucumber fermentation is traditionally done using lactic acid bacteria. The involvement of probiotic cultures in food fermentation guarantees enhanced organoleptic properties and protects food from spoilage.

Methods

Autochthonous lactic acid bacteria were isolated from spontaneously fermented cucumber and identified to species level. Only strains adjudged as safe for human consumption were examined for their technological and functional characteristics. Strain efficiency was based on maintaining high numbers of viable cells during simulated GIT conditions and fermentation, significant antioxidant activity, EPS production, nitrite degradation, and antimicrobial ability against Gram-positive and Gram-negative foodborne pathogens.

Result

Two strains, Lactiplantibacillus plantarum NPL 1258 and Pediococcus pentosaceus NPL 1264, showing a suite of promising functional and technological attributes, were selected as a mixed-species starter for carrying out a controlled lactic acid fermentations of a native cucumber variety. This consortium showed a faster lactic acid-based acidification with more viable cells, at 4% NaCl and 0.2% inulin (w/v) relative to its constituent strains when tested individually. Sensory evaluation rated the lactofermented cucumber acceptable based on texture, taste, aroma, and aftertaste.

Conclusion

The results suggest that the autochthonous LAB starter cultures can shorten the fermentation cycle and reduce pathogenic organism’ population, thus improving the shelf life and quality of fermented cucumber. The development of these new industrial starters would increase the competitiveness of production and open the country’s frontiers in the fermented vegetable market.

Foodborne ESKAPE Biofilms and Antimicrobial Resistance: lessons Learned from Clinical Isolates

The ESKAPE pathogens (Enterococcus spp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) are identified to be multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan drug-resistant (PDR); thereby, imposing severe challenges in the treatment of associated infections. ESKAPE pathogens colonize on various biotic and abiotic surfaces; biofilms formed by these pathogens are a potential source for food contamination. Moreover, biofilms play a pivotal role in the development of antimicrobial-resistant (AMR) strains. Hence, the frequent isolation of antimicrobial-resistant ESKAPE pathogens from food products across the globe imposes a threat to public health. A comprehensive understanding of the adhesion signaling involved in the polymicrobial and single-species biofilm will assist in developing alternative preservation techniques and novel therapeutic strategies to combat ESKAPE pathogens. The review provides a comprehensive overview of the signaling mechanisms that prevail in the ESKAPE pathogens for adhesion to abiotic and biotic surfaces and molecular mechanisms associated with poly-microbial biofilm-assisted AMR in ESKAPE.

Bacterial communities in bovine ejaculates and their impact on the semen quality

Although bacterial contamination of ejaculates may cause difficulties in cattle reproduction, standard protocols for a routine microbiological analysis of bovine semen are still missing. Understanding of the mechanisms of bacterial damage to spermatozoa may contribute to the prevention and management of bacteriospermia in the future. Therefore, this study was designed to investigate bacterial profiles of fresh bovine ejaculates (n = 30), while at the same time we focused on assessing the relationships between bacteriospermia and selected sperm quality parameters as well as an array of oxidative stress and inflammatory markers. The samples were divided into three quality groups according to the sperm motility: Excellent (EX) - over 90% > Good (GO) - between 89% and 80% > Moderate (MO) - under 80%. The results showed a significant increase in reactive oxygen species (ROS) generation in the GO group when compared to the EX group. In the MO group, a deterioration of almost all quality parameters was observed when compared to the EX group. In particular, sperm motility, mitochondrial membrane potential, ROS production and IL-6 concentration exhibited a significant decline. Pearson correlation analysis revealed positive associations among bacterial load and the presence of leukocytes in semen (r = 0.965), malondialdehyde concentration (r = 0.816) and DNA fragmentation (r = 0.784). MALDI-TOF MS Biotyper analysis showed a prevalence of the Staphylococcus genus. The quantification of bacterial colonies revealed a significantly increased (P < 0.01) bacterial load in the MO group when compared with the EX as well as the GO group. Overall, our results suggest that sperm quality may be affected by both, bacterial composition, and bacterial load. It appears that an increased presence of bacterial species triggers the immune response, causes oxidative stress, and thereby contributes to sperm structural alterations while diminishing their fertilization ability.Abbreviations: EX: Excellent; GO: Good; MO: Moderate; MOT: Motility; ROS: Reactive Oxygen Species; MMP: Mitochondrial Membrane Potential; IL-1: Interleukin 1; IL-6: Interleukin 6; IL-8: Interleukin 8; IL-12: Interleukin 12; CRP: C-reactive protein; DNA: Deoxyribonucleic acid; MALDI-TOF MS: Matrix-assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry; LPO: Lipid peroxidation; CFU: Colony-forming units MDA: Malondialdehyde; CASA: Computer-assisted Sperm Analysis; WS: Working solution; RIPA: Radio-immunoprecipitation assay; TBARS: Thiobarbituric Acid Reactive Substances; BHB: D-β-hydroxybutyrate.

Trans-Cinnamaldehyde Attenuates Enterococcus faecalis Virulence and Inhibits Biofilm Formation

Enterococcus faecalis as an important nosocomial pathogen is critically implicated in the pathogenesis of endocarditis, urinary tract, and persistent root canal infections. Its major virulence attributes (biofilm formation, production of proteases, and hemolytic toxins) enable it to cause extensive host tissue damage. With the alarming increase in enterococcal resistance to antibiotics, novel therapeutics are required to inhibit E. faecalis biofilm formation and virulence. Trans-cinnamaldehyde (TC), the main phytochemical in cinnamon essential oils, has demonstrated promising activity against a wide range of pathogens. Here, we comprehensively investigated the effect of TC on planktonic growth, biofilm formation, proteolytic and hemolytic activities, as well as gene regulation in E. faecalis. Our findings revealed that sub-inhibitory concentrations of TC reduced biofilm formation, biofilm exopolysaccharides, as well as its proteolytic and hemolytic activities. Mechanistic studies revealed significant downregulation of the quorum sensing fsr locus and downstream gelE, which are major virulence regulators in E. faecalis. Taken together, our study highlights the potential of TC to inhibit E. faecalis biofilm formation and its virulence.

The Role of Whole Genome Sequencing in the Surveillance of Antimicrobial Resistant Enterococcus spp.: A Scoping Review

Enterococcus spp. have arisen as important nosocomial pathogens and are ubiquitous in the gastrointestinal tracts of animals and the environment. They carry many intrinsic and acquired antimicrobial resistance genes. Because of this, surveillance of Enterococcus spp. has become important with whole genome sequencing emerging as the preferred method for the characterization of enterococci. A scoping review was designed to determine how the use of whole genome sequencing in the surveillance of Enterococcus spp. adds to our knowledge of antimicrobial resistance in Enterococcus spp. Scoping review design was guided by the PRISMA extension and checklist and JBI Reviewer's Guide for scoping reviews. A total of 72 articles were included in the review. Of the 72 articles included, 48.6% did not state an association with a surveillance program and 87.5% of articles identified Enterococcus faecium. The majority of articles included isolates from human clinical or screening samples. Significant findings from the articles included novel sequence types, the increasing prevalence of vancomycin-resistant enterococci in hospitals, and the importance of surveillance or screening for enterococci. The ability of enterococci to adapt and persist within a wide range of environments was also a key finding. These studies emphasize the importance of ongoing surveillance of enterococci from a One Health perspective. More studies are needed to compare the whole genome sequences of human enterococcal isolates to those from food animals, food products, the environment, and companion animals.

First characterization of Tn1546-like structures of vancomycin-resistant Enterococcus faecium Thai isolates

INTRODUCTION

Vancomycin-resistant Enterococcus faecium (VREfm) carrying vanA was first isolated from patient at Siriraj Hospital, Thailand in 2004. Since then, VREfm isolates have been detected increasingly in this 2500-bed university hospital. To understand the epidemiology of vanA VREfm in this setting, the isolates collected during 2004-2013 were characterized.

METHODS

A total of 49 vanA VREfm isolates previously confirmed by multiplex PCR were characterized by determining resistance phenotypes to vancomycin, teicoplanin, ampicillin and ciprofloxacin by broth microdilution method. Multilocus sequence typing (MLST) and virulence genes of those isolates were investigated. The Tn1546 structure diversity was studied by long-range overlapping PCR and primer walking sequencing.

RESULTS

Of all isolates studied, 9 sequence types (ST17, ST80, ST78, ST730, ST203, ST18, ST280, ST64, ST323) in clonal complex 17 and a novel ST1051 were revealed. The esp-positive isolates were 73.5%. Of all vanA operons characterized, at least 9 types of Tn1546-like structures were detected. All of vanA determinants contained 5'-end different from the Tn1546 prototype. Approximately 47% of them also carried the insertion sequence IS1251 at the intergenic region between vanS and vanH. Interestingly, another IS (ISEfa4) was found to be inside the sequence of IS1251 in ST17 isolate.

CONCLUSION

Heterogeneity of vanA VREfm was observed. Nearly all of isolates studied belonged to CC17. One novel ST1051 strain was detected. Isolates in the initial period carried vanA operon similar to the prototype. The diversity of vanA determinants has been increased in the recent isolates. A novel vanA operon structure was detected.

Molecular Characteristics of Enterococcus faecalis and Enterococcus faecium from Bulk Tank Milk in Korea

Simple Summary

Enterococci can be an opportunistic pathogen in milk, which can easily disseminate antimicrobial resistance and virulence genes. The purpose of this study was to characterize and compare the enterococci isolates from samples of bulk tank milk obtained from four dairy companies in Korea to prevent the spread of pathogenic and antimicrobial-resistant enterococci in dairy companies. The results demonstrated various degrees of antimicrobial resistance and virulence-factor distribution in enterococci from bulk tank milk in Korea and support the assessment that pathogens from bulk tank milk can also become a reservoir for dissemination of antimicrobial resistance and virulence factors through cross-contamination processes.

Abstract

Enterococci are considered to be environmental mastitis-causing pathogens that can easily spread antimicrobial resistance or virulence genes via horizontal transfer. In this study, the molecular characteristics of enterococci from bulk tank milk were investigated to assess the importance of dairy herd management. A total of 338 enterococci (305 Enterococcus faecalis and 33 Enterococcus faecium) were isolated from 1584 batches of bulk tank milk samples from 396 farms affiliated with four dairy companies in Korea, and significant differences (40.6–79.7%) (p < 0.05) in the prevalence of enterococci were observed in the samples from different companies. Enterococci showed the highest resistance to tetracycline (TET) (73.4%), followed by doxycycline (DOX) (49.7%) and erythromycin (ERY) (46.2%), while two enterococci isolates showed resistance to vancomycin (VAN). Among 146 tetracycline (TET) and ERY-resistant enterococci, each 50 (19.4%) enterococci carried combination-resistance and transposon gene types erm(B) + tet(M) + IntTn and erm(B) + tet(L) + tet(M) + IntTn, respectively. The virulence genes such as ace (99.0%), efaA (97.7%), cad1 (95.7%), and gelE (85.9%) were highly conserved in E. faecalis and significantly predominated over E. faecium (p < 0.001). Our results indicate that pathogens from bulk tank milk can also become a reservoir for the dissemination of antimicrobial resistance and virulence factors through cross-contamination processes.

Characteristics of Aerococcus viridans isolated from porcine fetuses in Korean farms

Swine abortion caused by viruses as well as bacteria has caused many economic losses in domestic farms over the years; however, bacterial abortion has not yet been studied in Korea. Several bacterial species were isolated from aborted fetuses (n = 103) for which the cause of death was not viral abortion. Among them, we focused on Aerococcus viridans, which had the highest positive rate within three provinces (Gangwon, Jeonnam and Gyeongnam). A total of 16 isolates were identified as A. viridans by matrix‐assisted laser desorption ionization‐time of flight mass spectrometry (MALDI‐TOF MS), and 13 were characterized by both antibiotic resistance and 16S rRNA gene analysis. Based on antibiotic susceptibility testing result, eight antimicrobials could not effectively eliminate the present isolation (more than 40% of isolates can resist these antibiotics), while all except two strains were susceptible to trimethoprim/sulfamethoxazole. Molecular analysis indicated genetic variation among these strains. This study is the first report detecting A. viridans from aborted fetuses in Korean domestic farms.

Pathogenic potential of Enterococcus faecalis strains isolated from root canals after unsuccessful endodontic treatment

OBJECTIVES

To evaluate strains of Enterococcus faecalis isolated from endodontic failures cases for (a) presence of virulence genes, namely, gelatinase production (gelE), surface protein (esp), collagen-binding adhesin (ace), cytolysin activator (cylA), E. faecalis antigen A (efaA) and aggregation substance (asa), all by using PCR; (b) biofilm formation capacity; and (c) activity of gelatinase and β-lactamase.

MATERIALS AND METHODS

Twenty-five strains of E. faecalis were tested. The DNA extracted from these strains was used for identification of virulence genes by PCR and 1% agarose gel. Biofilm formation was performed on polystyrene microplates by using the violet crystal staining method. For assessment of the gelatinase activity, inoculum of pure cultures was deposited in tubes containing gelatin and a nutrient broth, whereas nitrocefin disks were used to assess the β-lactamase action.

RESULTS

The virulence genes efaA and cylA were detected in 100% of the strains, whereas gelE was present in 84%, ace in 68%, esp in 56% and asa in 48%. Four strains had no biofilm formation, 17 had poor formation and four had moderate formation. Gelatinase production was observed in three strains and β-lactamase resistance in five strains of E. faecalis.

TOPIC

Diverse patterns of virulence gene detection were observed among the E. faecalis strains, with predominance of those capable of forming biofilm. A few strains have been found to hydrolyze gelatin proteins, whereas β-lactamase resistance was detected in different isolates.

CLINICAL RELEVANCE

To understand the influence of virulence factors in E. faecalis on the host heath status.

The Prevalence of Virulent and Multidrug-Resistant Enterococci in River Water and in Treated and Untreated Municipal and Hospital Wastewater

The aim of this study is to describe the drug resistance and virulence of enterococci in river water sampled downstream (DRW) and upstream (URW) from the wastewater discharge point, to determine the pool of virulent and drug-resistant enterococci in untreated wastewater (UWW) and the extent to which these bacteria are eliminated from hospital wastewater (HWW) and municipal wastewater treated (TWW) by biological and mechanical methods in a wastewater treatment plant (WWTP). A total of 283 strains were identified with the use of culture-dependent methods and PCR, including seven different species including E. faecalis and E. faecium which were predominant in all analyzed samples. Majority of the strains were classified as multidrug resistant (MDR), mostly on streptomycin and trimethoprim. Strains isolated from wastewater and DRW harbored van genes conditioning phenotypic resistance to vancomycin, the highest percentage of vancomycin-resistant strains (57.0%), mostly strains harboring vanC1 genes (27.6%), was noted in TWW. More than 65.0% of the isolated strains had different virulence genes, the highest number of isolates were positive for cell wall adhesin efaA and sex pheromones cob, cpd, and ccf which participate in the induction of virulence. Many of the strains isolated from TWW were resistant to a higher number of drugs and were more virulent than those isolated from UWW and HWW. The enterococci isolated from DRW and wastewater were characterized by similar multidrug resistance and virulence profiles, and significant correlations were observed between these groups of isolates. These findings suggest that pathogenic enterococci are released with TWW and can spread in the river, pose a serious epidemiological threat and a risk to public health.

Characterization of Enterococcus faecalis in different culture conditions

The aim of this study was to investigate how carbohydrates (glucose or sucrose) affect the characteristics of Enterococcus faecalis (E. faecalis) planktonic and biofilm in vitro. For this study, E. faecalis was cultured in tryptone-yeast extract broth with 0% glucose + 0% sucrose, 0.5% glucose, 1% glucose, 0.5% sucrose, or 1% sucrose. Viability of E. faecalis was examined by colony forming unit counting assays. Biofilm formation was assessed by measuring extracellular DNA (eDNA), a component of the biofilm matrix. Quantitative real-time PCR (qRT-PCR) was performed to investigate the expression of virulence-associated genes. Field emission scanning electron microscopy analysis, confocal laser scanning microscopy analysis, and crystal violet colorimetric assay were conducted to study E. faecalis biofilms. E. faecalis showed the highest viability and eDNA levels in 1% sucrose medium in biofilms. The result of qRT-PCR showed that the virulence-associated genes expressed highest in 1% sucrose-grown biofilms and in 1% glucose-grown planktonic cultures. E. faecalis showed highly aggregated biofilms and higher bacteria and exopolysaccharide (EPS) bio-volume in sucrose than in 0% glucose + 0% sucrose or glucose. The results indicate that the production of eDNA and EPS and expression of virulence-associated genes in E. faecalis are affected by the concentration of carbohydrates in biofilm or planktonic culture.

Gut microbiota characteristics in mice with antibiotic-associated diarrhea

BACKGROUND

Antibiotic-associated diarrhea (AAD), defined as diarrhea that occurs in association with the administration of antibiotics and without another clear etiology, is one of the most common adverse drug events of antibiotics therapy. We established a diarrhea model induced by gentamycin and cefradine to investigate the microbiota characteristics in the intestinal lumen of mice with AAD and provide insights into noteworthy bacteria related to gentamicin and cefradine-associated diarrhea.

RESULTS

The number of OTUs in the model group and the normal group was 983 and 2107, respectively, and 872 identical OTUs were shared between two groups. Species richness and species diversity of intestinal microbe were altered by antibiotics administration. PCoA showed a clear separation between AAD and health control. The dominant phyla of AAD mice were Firmicutes (52.63%) and Proteobacteria (46.37%). Among the genus with top 20 abundance, the relative abundance of 7 genera, Ruminococcus, Blautia, Enterococcus, Eubacterium, Clostridium, Coprococcus, and Aerococcus, were enriched in the model group. Based upon the LEfSe analysis, Enterococcus, Eubacterium, Ruminococcus, and Blautia were identified as potential biomarkers for AAD.

CONCLUSIONS

The bacterial diversity of the intestinal lumen was diminished after gentamicin and cefradine administration. The alterations in the abundance and composition of gut microbiota further led to the dysfunction of gut microbiota. More specifically, gentamicin and cefradine significantly increased the abundance of the opportunistic pathogens, of which Enterococcus and Clostridium were the most prominent and most worthy of attention.

Phenotypic and Molecular Characterization of Plasmid-Mediated Virulence and Antimicrobial Resistance Traits among Multidrug Resistant Enterococcus spp. in Egypt

Enterococcus spp. are remarkable multidrug resistant (MDR) bacteria that are causing serious healthcare-associated infections. The current study investigated the frequency of Enterococcus spp., antimicrobial susceptibility, biofilm formation and the presence of some plasmid-mediated virulence characters and antimicrobial resistance determinants in enterococcal isolates from Egyptian hospitals in Cairo. Enterococcus bacterial isolates were recovered from different clinical specimens and identified using biochemical testing and KB005A HiStrep™ identification kit. Kirby-Bauer disc diffusion method and/or broth microdilution method were used to determine the antimicrobial susceptibility patterns. Phenotypic assays were performed to study biofilm formation and cytolysin and gelatinase production. PCR assays targeting the plasmid-carried genes aac(6’)-aph(2’), aph(3)-IIIa, vanA, agg and cylA were performed. In this study, 50 isolates of diverse Enterococcus spp. were identified with E. faecium was the most frequently isolated one. High resistance profiles were determined against tested antimicrobials and all isolates were MDR. Moderate biofilm formation was detected in 20% of isolates, 18% showed complete blood hemolysis and 12% produced gelatinase. All isolates carried the tested aminoglycosides resistance genes, while vanA was found only in 4 isolates (8%). The virulence genes agg and cylA were detected in 4% and 32% of isolates, respectively. In conclusion, E. faecium was the most prevalent species. The entire isolates set were MDR and the plasmid-carried aminoglycoside resistance genes were extensively disseminated among MDR isolates. Thus, regular surveillance studies, from the area of study or other geographical regions in Egypt, and strict infection control measures are required to monitor the emerging MDR enterococci.

Effect of using diode laser on Enterococcus faecalis and its lipoteichoic acid (LTA) in chronic apical periodontitis

The purpose of this study was to evaluate the effect of diode laser irradiation on Enterococcus faecalis (E. faecalis) and its lipoteichoic acid (LTA). Ninety-six freshly extracted single-rooted teeth were divided into six groups, n = 8 per group. Groups 1, 2, 3, and 4 as laser group (810 nm PILOT™ Diode Laser, 400 μm fiber diameter, continuous mode, 30 s time) with powers at 1.0 W, 1.5 W, 2.0 W, and 2.5 W respectively. Group 5 or positive control group (3 ml of 1% sodium hypochlorite (NaOCl) irrigation) and group 6 or negative control group (3 ml of normal saline (0.9% NaCl) irrigation). Root canal samples were collected before and after receiving laser irradiation and irrigation solution. Cultivable bacteria were determined by counting the colony (CFU/ml). Evaluation of temperature on the external root surface of teeth was done with K type thermocouple using laser at different powers. Enzyme-linked immunosorbant assay (ELISA) was performed to measure the LTA levels and the correlations between E. faecalis count, LTA levels, and rise in temperature were observed using Pearson's correlation test. E. faecalis LTA was subjected to laser irradiation and its structural damage was examined by thin layer chromatography (TLC). Compared with the control groups, all laser groups showed a decreased colony counts and decreased LTA levels with statistically significant difference (p ˂ 0.05). The bactericidal effect and LTA reduction of laser was better at 2.5 W power. Laser at 2.5 W power had temperature rise of more than 7 °C which is beyond the safe thermal threshold level. No statistically significant correlation was found between E. faecalis count, levels of LTA, and rise in external root surface temperature (p ˃ 0.05). TLC results showed a structural damage in the glycolipid moiety of E. faecalis LTA. Diode laser can effectively reduce the E. faecalis count and its LTA levels.

Genetic relatedness of the Enterococcus faecalis isolates in stool and urine samples of patients with community-acquired urinary tract infection

Background

Community-acquired urinary tract infection (CA-UTI) could be caused by endogenous or exogenous routes. To show this relationship, we investigated molecular fingerprints and genotypes of paired Enterococcus faecalis isolated from the urine of symptomatic patients and their fecal samples.

Results

Out of the studied patients, 63 pairs of E. faecalis isolates were obtained simultaneously from their urine and feces samples. All the strains were sensitive to vancomycin, linezolid, nitrofurantoin, and daptomycin (MIC value: ≤ 4 µg/ml), while resistance to tetracycline (urine: 88.9%; stool: 76.2%) and minocycline (urine: 87.3%, stool: 71.4%) was detected in most of them. The most common detected virulence genes were included efbA, ace, and gelE. RAPD-PCR and PFGE analyses showed the same patterns of molecular fingerprints between paired of the isolates in 26.9% and 15.8% of the patients, respectively.

Conclusions

Similarity of E. faecalis strains between the urine and feces samples confirmed the occurrence of endogenous infection via contamination with colonized bacteria in the intestinal tract. Carriage of a complete virulence genotype in the responsible strains was statistically in correlation with endogenous UTI, which shows their possible involvement in pathogenicity of uropathogenic E. faecalis strains.

Improved detection of esp, hyl, asa1, gelE, cylA virulence genes among clinical isolates of Enterococci

Objective

Virulence factors (VFs) among the clinical strains of enterococci play a vital role in pathogenesis. This study was aimed to screen for cylA, asa1, gelE, esp and hyl among Enterococcus faecalis (n = 89) and E. faecium (n = 51) by multiplex PCR. The previously reported multiplex PCR was modified to 2 duplex (asa1 and gelE, cylA and esp) PCRs and 1 simplex (hyl) PCR. The idea of the modification of the multiplex PCR proposed here emerged in the course of the research study when majority of the isolates which phenotypically exhibited virulence traits were found to be negative for the respective gene.

Results

cylA, gelE and asa1 were significantly predominant in E. faecalis (59.55%, 85.39%, 86.51%) than E. faecium (1.96%, 60.78%, 9.80%) (p < 0.0001, p = 0.001967, p < 0.0001). hyl was detected in E. faecium (5.9%) only. The number of VFs detected in each isolate was recorded as the VF score. E. faecalis isolates had a VF score pattern of score 4 (34.83%), score 3 (26.96%), score 2 (28.08%) and score 1 (8.98%) while E. faecium had score 4 (1.96%), score 3 (7.84%), score 2 (25.49%) and score 1 (41.18%). This modification of the PCR protocol could resolve the problem of decreased detection of virulence determinants in enterococci.

Antimicrobial resistance monitoring of commensal Enterococcus faecalis in broiler breeders

Enterococcus faecalis (E. faecalis) has rapidly acquired resistance to multiple antimicrobials, and the antimicrobial resistance of E. faecalis from broiler breeders has been implicated in its vertical transmission to their offspring. The objective of this study was to investigate the antimicrobial resistance and genetic diversity of commensal E. faecalis isolated from the broiler breeder farms. Among a total of 229 E. faecalis isolates from 9 broiler breeder farms, the highest resistance rate was observed in tetracycline (78.2%), followed by doxycycline (58.1%) and erythromycin (43.7%), and the prevalence of antimicrobial resistance showed significant differences among the 9 broiler breeder farms (P < 0.05). The tetM gene (77.1%) and ermB gene (85.0%) were detected at the highest levels in 179 TE-and 100 E-resistant isolates, respectively. Twenty-four high-level gentamicin-resistant isolates carried aac(6″)Ie-aph(2″)-la gene, and 9 high-level ciprofloxacin-resistant isolates showed point mutations in both gyrA and parC genes. All high-level gentamicin-resistant or high-level ciprofloxacin-resistant isolates showed one of the two different virulence gene patterns, ace-asa1-efaA-gelE complex or ace-efaA-gelE complex. These results indicate that constant epidemiological monitoring at the breeder level is required to prevent the pyramidal transmission of antimicrobial-resistant E. faecalis.

Comparative genomics of multidrug-resistant Enterococcus spp. isolated from wastewater treatment plants

BACKGROUND

Wastewater treatment plants (WWTPs) are considered hotspots for the environmental dissemination of antimicrobial resistance (AMR) determinants. Vancomycin-Resistant Enterococcus (VRE) are candidates for gauging the degree of AMR bacteria in wastewater. Enterococcus faecalis and Enterococcus faecium are recognized indicators of fecal contamination in water. Comparative genomics of enterococci isolated from conventional activated sludge (CAS) and biological aerated filter (BAF) WWTPs was conducted.

RESULTS

VRE isolates, including E. faecalis (n = 24), E. faecium (n = 11), E. casseliflavus (n = 2) and E. gallinarum (n = 2) were selected for sequencing based on WWTP source, species and AMR phenotype. The pangenomes of E. faecium and E. faecalis were both open. The genomic fraction related to the mobilome was positively correlated with genome size in E. faecium (p < 0.001) and E. faecalis (p < 0.001) and with the number of AMR genes in E. faecium (p = 0.005). Genes conferring vancomycin resistance, including vanA and vanM (E. faecium), vanG (E. faecalis), and vanC (E. casseliflavus/E. gallinarum), were detected in 20 genomes. The most prominent functional AMR genes were efflux pumps and transporters. A minimum of 16, 6, 5 and 3 virulence genes were detected in E. faecium, E. faecalis, E. casseliflavus and E. gallinarum, respectively. Virulence genes were more common in E. faecalis and E. faecium, than E. casseliflavus and E. gallinarum. A number of mobile genetic elements were shared among species. Functional CRISPR/Cas arrays were detected in 13 E. faecalis genomes, with all but one also containing a prophage. The lack of a functional CRISPR/Cas arrays was associated with multi-drug resistance in E. faecium. Phylogenetic analysis demonstrated differential clustering of isolates based on original source but not WWTP. Genes related to phage and CRISPR/Cas arrays could potentially serve as environmental biomarkers.

CONCLUSIONS

There was no discernible difference between enterococcal genomes from the CAS and BAF WWTPs. E. faecalis and E. faecium have smaller genomes and harbor more virulence, AMR, and mobile genetic elements than other Enterococcus spp.

Safety and technological application of autochthonous Streptococcus thermophilus cultures in the buffalo Mozzarella cheese

Thermophilic and mesophilic lactic acid bacteria (LAB), such as Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus helveticus, and Lactococcus lactis, play a crucial role in the technological and sensory quality of Mozzarella cheese. In this study, the safety (genes encoding virulence factors and antibiotic resistance) and acidifying activity of autochthonous S. thermophilus cultures were evaluated in order to choose the most suitable strain for industrial application. The safe and good acidifying culture was tested in two buffalo Mozzarella cheese batches: Mozzarella cheeses produced with autochthonous culture (SJRP107) and commercial culture (STM5). The cultivable LAB was evaluated by culture-dependent method (plate counting) and the quantification of S. thermophilus cultures (commercial and autochthonous) were evaluated by culture-independent method RealT-qPCR (real-time quantitative polymerase chain reaction). The texture, physicochemical and proteolytic properties of the Mozzarella cheeses were similar for both batches. The nonstarter LAB count was higher during manufacture than in the storage, and the RealT-qPCR indicated the presence of S. thermophilus culture until the end of storage. S. thermophilus SJRP107 presented high potential for safety application in the production of Mozzarella cheese. Furthermore, considering the culture characteristics and their relationship with product quality, further studies could be helpful to determine their effect on the sensory characteristics of the cheese.

Molecular Characterization Of Vancomycin-Resistant Enterococcus faecalis Among Inpatients At Iranian University Hospitals: Clonal Dissemination Of ST6 And ST422

Purpose

Over the past two decades, enterococci have emerged as an important opportunistic pathogen causing life-threatening infections in hospitals. The purpose of the present study was to examine the prevalence of genes encoding virulence factor and molecular characterization of vancomycin-resistant E. faecalis strains isolated from hospitalized patients in Isfahan, the central city of Iran.

Patients and methods

A total of 53 vancomycin-resistant E. faecalis isolates (VRE) obtained from clinical samples of hospitalized patients were characterized by phenotypic and genotypic methods, and 25 selected VRE isolates from internal and ICU wards were typed by multilocus sequence typing.

Results

The efa was the most prevalent virulence gene (100%) among isolates, followed by gelE (92.45%), asa1 (90.56%), ace (86.79%), esp (75.47%), cylA (39.62%), and hyl (18.86%). More than 80% of the isolates were HLGR. Multilocus sequence typing showed eight different sequence types including ST6, ST422, ST28, ST448, ST531, ST328, ST421, and ST495. STs were grouped into two clonal complex (CC) including CCA (ST6, ST422, ST448, ST531) and CCF (ST28, ST421) and two singletons (ST328, ST495).

Conclusion

Our data indicated a high prevalence of virulence genes among STs described in this study. In addition, the molecular analysis demonstrated a relatively high genetic diversity among selected VRE strains from the ICU in comparison with the internal ward. Therefore, in order to prevent the colonization of virulent strains in the hospital environment, infection control procedures should be performed.

Molecular Cloning and Immunogenicity Evaluation of PpiC, GelE, and VS87_01105 Proteins of Enterococcus faecalis as Vaccine Candidates

Background

Among the enterococci strains, Enterococcus faecalis is considered as one of the important nosocomial pathogens affecting immunocompromised patients. In this study, the immunogenicity of PpiC, GelE, and VS87_01105 proteins against enterococcal infection was investigated in a mice model.

Methods

The genes encoding these proteins were cloned into pET21a expression vector, and the recombinant proteins were produced. Mice and rabbits were immunized with the purified recombinant proteins, and subsequently, mice were challenged with E. faecalis for the evaluation of their survival and bacterial clearances. The antibody responses to recombinant proteins were determined by ELISA assay, and opsonophagocytic activities of the antibodies were also measured. Passive immunization was performed using purified antibodies. Mice were challenged, and their survival and bacterial clearance were determined.

Results

Immunized mice with PpiC, GelE, and VS87_01105 recombinant proteins showed 80%, 70%, and 40% survival rate, respectively. The survival rates among passively immunized mice that received 500 µg of IgG fraction in 100 µl PBS buffer of each of anti-PpiC, anti-GelE, and anti-VS87_01105 were 60%, 50%, and 20%, respectively. The rates of opsonization with anti-PpiC, anti-GelE, and anti-VS87_01105 antibodies at 1/10 dilution were 77%, 64%, and 23%, respectively.

Conclusion

Based on our findings, PpiC, and GelE proteins can protect the mice against E. faecalis ATCC 29212 and effectively induce a protective antibody response. Thus, these proteins could be used as an additional therapeutic tool against enterococcal infections. Further studies to determine the role of PpiC in ligand binding and demonstration of epitope mapping may establish a credible target for vaccination.

High incidence of virulence determinants, aminoglycoside and vancomycin resistance in enterococci isolated from hospitalized patients in Northwest Iran

BACKGROUND

Multidrug resistant (MDR) enterococci are important nosocomial pathogens causing serious problem in hospitalized patients. The aim of present study was to investigate the frequency of high-level aminoglycoside-resistant and vancomycin-resistant enterococci (VRE) and virulence encoding genes in enterococci isolated from hospitalized patients.

METHODS

A total of 100 enterococci isolated from urine samples of hospitalized patients with symptomatic urinary tract infections were investigated for antimicrobial susceptibility, the frequency of aminoglycoside and vancomycin resistance genes (including aac (6')-Ie-aph (2")-Ia, aph (3')-IIIa, ant (4')-Ia, aph (2")-Ic, aph (2")-Ib, aph (2")-Id, ant (3″)-III, ant (6')-Ia, vanA, vanB and vanC) and virulence encoding genes (including gelE, PAI, esp, ace, cyl, hyl and sprE).

RESULTS

Enterococcus faecalis species was identified as predominant enterococci (69%), followed by "other" Enterococcus species (21%) and E. faecium (10%). Ninety three percent of isolates were resistant to one or more antimicrobial agents, with the most frequent resistance found against tetracycline (86%), ciprofloxacin (73%) and quinupristin-dalfopristin (53%). Gentamicin and streptomycin resistance were detected in 50 and 34% of isolates, respectively. The most prevalent aminoglycoside resistance genes were ant (3″)-III (78%) and aph (3')-IIIa (67%). Vancomycin resistance was detected in 21% of isolates. All E. faecium isolates carried vanA gene, whereas, the vanB gene was not detected in Enterococcus species. The most frequent virulence gene was ace (88.6%), followed by esp (67.1%), PAI (45.5%) and sprE (41.7%).

CONCLUSION

Our study revealed the high frequency of gentamycin resistance and VRE in E. faecium isolates, with a high prevalence and heterogeneity of virulence and resistance genes. Due to high frequency of MDR enterococci, it seems that the appropriate surveillance and control measures are essential to prevent the emergence and transmission of these isolates in hospitals.

Detecting Fingerprints of Waterborne Bacteria on a Sensor

Human fecal contamination is a crucial threat that results in difficulties in access to clean water. Enterococcus faecalis is a bacteria which is utilized as an indicator in polluted water. Nevertheless, existing strategies face several challenges, including low affinity and the need for labelling, which limit their access to large scale applications. Herein, a label-free fingerprint of the surface proteins of waterborne bacteria on a sensor was demonstrated for real-time bacteria detection from aqueous and water samples. The kinetic performance of the sensor was evaluated and shown to have a range of detection that spanned five orders of magnitude, having a low detection limit (3.4 × 104 cfu/mL) and a high correlation coefficient (R2 = 0.9957). The sensor also designated a high selectivity while other competitor bacteria were employed. The capability for multiple usage and long shelf-life are superior to other modalities. This is an impressive surface modification method that uses the target itself as a recognition element, ensuring a broad range of variability to replicate others with different structure, size and physical and chemical properties.

Investigation of Gelatinase Gene Expression and Growth of Enterococcus faecalis Clinical Isolates in Biofilm Models

Objectives

Enterococcus faecalis is the major reason for biofilm-related infections and it also interacts with Staphylococcus aureus in biofilms. Gelatinase (gelE) enzyme is an important virulence factor of E. faecalis for biofilm formation. This study aimed to compare the biofilm producing E. faecalis isolates from urine and urinary catheters. The influence of S. aureus on the growth of E. faecalis biofilm cells was also investigated in a dual biofilm model in vitro. Another aim was to evaluate E. faecalis gelE gene expression during biofilm formation.

Materials and Methods

Firstly, crystal violet staining was used to measure the total biofilm biomass of the isolates. Secondly, plate counting was performed to determine the biofilm formation ability of E. faecalis isolates and the effect of S. aureus on E. faecalis biofilm formation. Finally, the gelE expression profile of the isolates was assessed by quantitative real time-polymerase chain reaction.

Results

According to crystal violet staining and plate counting, all E. faecalis isolates were biofilm producers and the number of E. faecalis sessile cells increased in the presence of S. aureus. Among the 21 E. faecalis isolates, ten expressed high levels of the gelE gene, while eight of them had low expression profiles (p<0.05).

Conclusion

When they grow together, S. aureus may give some advantages to E. faecalis such as increasing sessile cell growth. The expression of the gelE gene was not affected by E. faecalis biofilm formation of the isolates collected from the patients with urinary tract infections.

Antimicrobial resistance pattern, virulence determinants and molecular analysis of Enterococcus faecium isolated from children infections in Iran

BACKGROUND

Enterococcus species continues to be an important cause of hospital-acquired infection worldwide. This study was designed to determine the antibiotic resistance profiles, virulence genes and molecular characteristics of Enterococcus faecium strains isolated from an Iranian children hospital in a four-years period.

RESULTS

A total 189 Enterococcus strains, comprising 108 (57%) E. faecium, 67 (35%) E. faecalis and 14 (7%) isolates of other spp. were isolated during the collection period. More than 92% of E. faecium isolates were resistant to ampicillin (92.5%), ciprofloxacin (96%), erythromycin (100%) and clindamycin (96%). A high frequency of resistance to clindamycin (100%), erythromycin (98.5%) and ciprofloxacin (80.5%) was observed among E. faecalis isolates, while resistance to ampicillin (7%) was less frequent. The prevalence of vanA gene among vancomycin resistant E. faecium and vancomycin resistant E. faecalis was 95 and 50%, respectively. The analysis of 108 E. faecium isolates revealed 34 variable number tandem repeat (VNTR) patterns and 27 Multi Locus VNTR Analysis (MLVA) types (MTs).

CONCLUSIONS

The results show a shift from E. faecalis to E. faecium as the dominant enterococcal species among patients at the children Hospital. Our data revealed that the majority of E. faecium isolates (66%) belonged to three common MTs and these types were isolated from different wards in children hospital.

Antimicrobial Resistance and Virulence Genes in Enterococcus faecium and Enterococcus faecalis from Humans and Retail Red Meat

The emergence of antimicrobial-resistant and virulent enterococci is a major public health concern. While enterococci are commonly found in food of animal origin, the knowledge on their zoonotic potential is limited. The aim of this study was to determine and compare the antimicrobial susceptibility and virulence traits of Enterococcus faecalis and Enterococcus faecium isolates from human clinical specimens and retail red meat in Slovenia. A total of 242 isolates were investigated: 101 from humans (71 E. faecalis, 30 E. faecium) and 141 from fresh beef and pork (120 E. faecalis, 21 E. faecium). The susceptibility to 12 antimicrobials was tested using a broth microdilution method, and the presence of seven common virulence genes was investigated using PCR. In both species, the distribution of several resistance phenotypes and virulence genes was disparate for isolates of different origin. All isolates were susceptible to daptomycin, linezolid, teicoplanin, and vancomycin. In both species, the susceptibility to antimicrobials was strongly associated with a food origin and the multidrug resistance, observed in 29.6% of E. faecalis and 73.3% E. faecium clinical isolates, with a clinical origin (Fisher's exact test). Among meat isolates, in total 66.0% of E. faecalis and E. faecium isolates were susceptible to all antimicrobials tested and 32.6% were resistant to either one or two antimicrobials. In E. faecalis, several virulence genes were significantly associated with a clinical origin; the most common (31.0%) gene pattern included all the tested genes except hyl. In meat isolates, the virulence genes were detected in E. faecalis only and the most common pattern included ace, efaA, and gelE (32.5%), of which gelE showed a statistically significant association with a clinical origin. These results emphasize the importance of E. faecalis in red meat as a reservoir of virulence genes involved in its persistence and human infections with reported severe outcomes.

Incidence of Virulence Determinants Among Enterococcal Clinical Isolates in Egypt and Its Association with Biofilm Formation

Background: Although Enterococci compromise an essential part of normal gut microbiota of both animals and humans, they have emerged as a leading opportunistic pathogen causing infections. The pathogenesis of enterococci is attributed to an array of virulence determinants. Objectives: This study aims to explore the prevalence and characteristics of enterococcal clinical isolates collected from Mansoura University Hospitals, Egypt, assess their ability to form biofilm, and the correlation with virulence determinants and antimicrobial resistance. Materials and Methods: A total of 70 Enterococcal clinical isolates were collected from different clinical sources between June and December 2016. Biofilm formation capacity was assessed, and characterization of virulence factors and antibiotic susceptibility was performed. Clonal relatedness between isolates was assessed using enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) approach. Results and Conclusion: The molecular analysis demonstrated high genetic diversity among enterococcal clinical isolates. The gelE was the most frequently detected gene (91.4%), followed by asa1 (70%), esp (65.7%), and cylA (17.1%), while hyl was not detected in any isolate. Gelatinase activity was detected in 35.7%, while hemolysin and lipase activity was detected in 12.9% and 78.5%, respectively. Most of the enterococcal isolates were biofilm producers, of which 67.1% were strong/moderate biofilm producers. All linezolid-resistant isolates exhibited strong/moderate biofilm formation capacity. Strong/moderate biofilm formation was more frequently observed among esp-positive (esp+) and gelatinase nonproducing (gelatinase-) enterococcal isolates. Multiple regression analysis denoted that esp (odds ratio [OR] 5.371, p = 0.003) and gelatinase production (OR 0.264, p = 0.015) were associated with strong/moderate biofilm formation capacity. These findings suggest that esp gene positivity and gelatinase production may affect biofilm formation capacity among enterococcal clinical isolates.

Prevalence of Aminoglycoside Resistance Genes in Enterococcus Strains in Kermanshah, Iran

BACKGROUND

This study aimed to investigate the occurrence of aminoglycoside resistance and the prevalence of the resistance-modifying enzyme genes, ant(3")-III, ant(6')-Ia, aac(6')-Ie-aph(2")-Ia, and aph(2')-Id, in Enterococcus strains isolated in Kermanshah Province, west of Iran.

METHODS

In this cross-sectional study, 108 enterococcal isolates from urine, wound, blood, and cerebrospinal fluid samples were collected. The Enterococcus species were recognized by standard phenotypic/biochemical tests. The antimicrobial resistance forms were detected using a disc diffusion method. Polymerase chain reaction was designed to identify aminoglycoside resistance genes, including ant(3")-III, ant(6')-Ia, aac(6')-Ie-aph(2")-Ia, and aph(2')-Id.

RESULTS

Totally, 108 strains with a final diagnosis of Enterococcus were extracted from 84 (77.8%) urine, 14 (13%) wound, 6 (5.6%) blood, and 4 (3.7%) cerebrospinal fluid samples. Among the 108 Enterococcus specimens, 94 (87%) cases were Enterococcus faecalis and 14 (13%) were Enterococcus faecium. The highest frequency of resistance was observed for erythromycin (88.9%), while the lowest was found for streptomycin (44.4%). The frequency of high-level gentamicin resistance was 42.2%. Among the identified specimens, 42.6% contained the aac(6')-Ie-aph(2")-I gene, 20.4% contained the ant(6')-Ia gene, and 15.7% contained the ant(3")-III gene. A significant correlation was found between phenotypic gentamicin resistance and the presence of the aminoglycoside resistance genes (P<0.05).

CONCLUSION

This study showed the high resistance of Enterococcus strains isolated from hospital samples. Compared with the previous studies, the strains isolated in our study showed a higher percentage of resistance to aminoglycosides.