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

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.

Virulence Determinants and Antimicrobial Resistance Patterns of Vancomycin-resistant Enterococcus faecium Isolated from Different Sources in Southwest Iran

BACKGROUND

This study aimed to investigate the incidence of antibiotic-resistance and virulence genes in vancomycin-resistant Enterococcus faecium isolated from different sources in southwest Iran from Mar to Sep 2015.

METHODS

Overall, 120 E. faecium isolates (80 VRE and 40 vancomycin-susceptible enterococci [VSE] isolates) were obtained from four hospitals. The resistance of the VRE isolates was determined by disk diffusion method. Multiplex PCR was performed to detect the virulence genes carried by the E. faecium isolates, namely, enterococcal surface protein (esp), hyaluronidase (hyl), and collagen-binding adhesin (acm).

RESULTS

All the VRE isolates exhibited multidrug resistance, with the rates of resistance to ampicillin, erythromycin, and ciprofloxacin reaching high levels. The isolates were least resistant to chloramphenicol and nitrofurantoin, but all of them were susceptible to linezolid. 46.6%, 20.8%, and 86.6% of the E.faecium isolates carried the esp, hyl, and acm genes, respectively.

CONCLUSION

There is a significant difference between the prevalence of esp and hyl genes in the VRE and VSE isolates. In the VRE isolates, the high prevalence of multidrug resistance were found and the difference in the prevalence of esp among various sources was significant. The findings reflected a relationship between the prevalence of esp and hyl and resistance to certain antibiotics.

Molecular Mechanism of Quorum-Sensing in Enterococcus faecalis: Its Role in Virulence and Therapeutic Approaches

Quorum-sensing systems control major virulence determinants in Enterococcusfaecalis, which causes nosocomial infections. The E. faecalis quorum-sensing systems include several virulence factors that are regulated by the cytolysin operon, which encodes the cytolysin toxin. In addition, the E. faecalis Fsr regulator system controls the expression of gelatinase, serine protease, and enterocin O16. The cytolysin and Fsr virulence factor systems are linked to enterococcal diseases that affect the health of humans and other host models. Therefore, there is substantial interest in understanding and targeting these regulatory pathways to develop novel therapies for enterococcal infection control. Quorum-sensing inhibitors could be potential therapeutic agents for attenuating the pathogenic effects of E. faecalis. Here, we discuss the regulation of cytolysin, the LuxS system, and the Fsr system, their role in E. faecalis-mediated infections, and possible therapeutic approaches to prevent E. faecalis infection.

High Incidence of Virulence Factors Among Clinical Enterococcus faecalis Isolates in Southwestern Iran

BACKGROUND

Over the past two decades, enterococci have emerged as an important agent responsible for hospital acquired infection. Several virulence factors contribute to the adherence, colonization, evasion of the host immune response, and pathogenicity and severity of the infection. Enterococcus faecalis is the most common and virulent species causing infections in hospitalized patients. The aim of the present study was to examine the prevalence of genes encoding virulence factors and antimicrobial resistance patterns of E. faecalis strains isolated from hospitalized patients in Shiraz, south west of Iran.

MATERIALS AND METHODS

A total of 51 E. faecalis isolates from the urine, blood, pleural fluid, peritoneal fluid, eye discharge, endotracheal tube (ETT) and transjugular intrahepatic portosystemic shunt (TIPS) specimens of patients were identified by phenotypic and genotypic methods. Antimicrobial sensitivity tests and detection of virulence factors were performed using standard methods.

RESULTS

The efa and asa1 were the most frequently detected gene (100%) among the isolates, followed by esp (94.1%), ace (90.2%), gelE (80.4%), cylA (64.7%), and hyl (51%). More than half of the isolates (52.9%) were high level gentamicin resistant (HLGR). Vancomycin resistance was observed among 23 (45.1%) isolates. The lowest antimicrobial activity was related to erythromycin (3.9%), tetracycline (5.9%) and ciprofloxacin (9.8%). No isolate was found resistant to fosfomycin and linezolid.

CONCLUSION

Our data indicated a high incidence of virulence factors among E. faecalis strains isolated from clinical samples. Colonization of drug resistant virulent isolates in hospital environment may lead to life threatening infection in hospitalized patients. Therefore, infection control procedures should be performed.