Prevalence of bacteriocin activities and bacteriocin-encoding genes in enterococcal clinical isolates in Iran

Characterization of bacteriocinogenic Enterococcus isolates from wild and laboratory rabbits for the selection of autochthonous probiotic strains in Tunisia

AIM

The objective of this study was to characterize lactic acid bacteria (LAB) from rabbits to be used as potential autochthonous probiotic.

METHODS AND RESULTS

Fifteen faecal samples were collected from wild and laboratory rabbits. One hundred and eight isolates were collected and tested for their inhibitory power against eight pathogenic bacteria. Among them, 43 Enterococcus isolates were able to inhibit at least one pathogen. Enterocine genes entA, entB and entP were detected in 14, 17 and 22 isolates, respectively. These isolates were tested for their antibiotic susceptibility and genes encoding virulence factors. Relevant phenotypes of antibiotic resistance were observed especially for ampicillin, vancomycin and linezolid. The following virulence genes were detected (number of positive isolates): hyl (5), esp (8), gelE (30), agg (2), ace (21), efa (6), CylL_L/s (5), cob (26), cpd (32) and ccf (33). Five isolates were considered as safe and showed tolerance to both acid and bile salt.

CONCLUSION

Bacteriocinogenic enterococci isolates from rabbits may show relevant resistance phenotypes and virulence factors. In addition, one Enterococcus durans isolate presents promising autochthonous probiotic candidate.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study reveals interesting properties for E. durans isolate and supports their utilization as autochthonous probiotic in rabbit husbandry.

Recent advances in the application of probiotic yeasts, particularly Saccharomyces, as an adjuvant therapy in the management of cancer with focus on colorectal cancer

Today, the increasing rate of cancer-related mortality, has rendered cancer a major global challenge, and the second leading cause of death worldwide. Conventional approaches in the treatment of cancer mainly include chemotherapy, surgery, immunotherapy, and radiotherapy. However, these approaches still come with certain disadvantages, including drug resistance, and different side effects such as gastrointestinal (GI) irritation (e.g., diarrhea, mucositis). This has encouraged scientists to look for alternative therapeutic methods and adjuvant therapies for a more proper treatment of malignancies. Application of probiotics as an adjuvant therapy in the clinical management of cancer appears to be a promising strategy, with several notable advantages, e.g., increased safety, higher tolerance, and negligible GI side effects. Both in vivo and in vitro analyses have indicated the active role of yeast probiotics in mitigating the rate of cancer cell proliferation, and the induction of apoptosis through regulating the expression of cancer-related genes and cellular pathways. Strain-specific anti-cancer activities of yeast probiotics strongly suggest that their administration along with the current cancer therapies may be an efficient method to reduce the side effects of these approaches. The main purpose of this article is to evaluate the efficacy of yeast probiotics in alleviating the adverse effects associated with cancer therapies.

Antimicrobial activity of enterocins against Listeria sp. and other food spoilage bacteria

OBJECTIVE

To determine bacteriocin producers and the prevalence of structural enterocin genes and to detect the spectrum of activity against foodborne pathogens, from isolates of Enterococcus faecium and Enterococcus faecalis that were isolated from food and the environment.

RESULTS

The entA, entB, entP, ent1071 and entX genes, which encode enterocins were the most frequently observed. Enterocins were thermostable, proteinaceous, and resistant to catalase. None of the isolates produced hemolysin, and inhibition resulting from bacteriophage lysis was excluded. The bactericidal effect of enterocins against L. innocua 12612 was determined by optical density and colony forming units. For the activity spectrum, elimination of mainly Listeria strains, Bacillus sp. and clinical enterococci, was observed. Imaging with scanning electron microscopy after treatment with enterocin Efm22 showed irregular rod-shaped cells and loss of cellular integrity.

CONCLUSIONS

The isolates evaluated in this study are candidates for the production of enterocins that will be used as food biopreservatives, because they have high anti-listerial activity even after 24 h of experimentation, and used in the pharmaceutical area because they inhibit clinical microorganisms.

Occurrence of Enterococcus faecalis and Enterococcus faecium in Various Clinical Infections: Detection of Their Drug Resistance and Virulence Determinants

The aim of this study was to characterize virulence determinants and antibiotic resistance profiles in enterococci obtained from various clinical sources in the northwest of Iran. A total of 160 enterococcal clinical isolates from various wards of University Teaching Hospitals were collected and specified by biochemical test, from September 2014 to July 2015. Identification of enterococci was confirmed by multiplex PCR in the genus and species level. Antibiotic resistance properties and virulence determinants were examined by phenotypic and molecular methods. Of 160 enterococcal isolates, 125 (78.12%) and 35 (21.88%) isolates were identified as Enterococcus faecalis and Enterococcus faecium, respectively. The most common antibiotic nonsusceptible pattern observed was resistance toward rifampicin [n = 122 (76.25%)] followed by erythromycin [n = 117 (73.12%)]. Among all isolates, gelE [n = 140 (87.5%)], cpd [n = 137 (85.6%)], and asa1 [n = 118 (73.8%)] were the most prevalent virulence genes studied. Thirty isolates (11 E. faecalis, 19 E. faecium) were found to be resistant to vancomycin, with minimum inhibitory concentration of ≥256 μg/ml. Twenty-seven isolates carried the vanA gene, whereas none of the isolates carried vanB. E. faecalis had a considerable ability to show virulence genes and drug resistance. Emergence of antibiotic-resistant enterococci and the high prevalence of virulence traits in our study could be regarded as an alarming situation.

An Overview on Novel Microbial Determination Methods in Pharmaceutical and Food Quality Control

Traditional microbiological methods tend to be labor-intensive and time-consuming. Rapid and novel methods in microbiological tests provide more sensitive, precise and reproducible results compared with conventional methods. In microbiology, the most rapid testing methods belong to the field of biotechnology such as PCR, ELISA, ATP bioluminescence and etc. Nevertheless impedance microbiology, biosensors and analytical procedures to determine microbial constituents are of significance. The present review article was conducted using internet databases and related scientific literatures and articles that provide information on developments in the rapid methods in microbiology. The main focus is on the application of rapid methods in microbial quality control of pharmaceutical products. Reviewed literature showed that rapid methods and automation in microbiology is an advanced area for studying and applying of improved methods in the early detection, and characterization of microorganisms and their products in food, pharmaceutical and cosmetic industrials as well as environmental monitoring and clinical applications. It can be concluded that rapid methods and automation in microbiology should continue as potent and efficient technologies to develop the novel tests to be performed in the future because of the ever-increasing concerns about the safety of food and pharmaceutical products. However the main issues to be considered are the scale up of developed methods and the regulatory requirements.

Efficient Inactivation of Multi-Antibiotics Resistant Nosocomial Enterococci by Purified Hiracin Bacteriocin

PURPOSE

Because of the emergence of multi-antibiotic resistant bacteria, a number of infectious diseases have become a major concern to treat in health care services worldwide. This situation is worsened by the fact that very limited progress has been made in developing new and potent antibiotics in recent years. In this context antimicrobial peptides (AMPs) represent new potential therapeutic compounds with bactericidal or bacteriostatic activity against closely related bacterial strains.

METHODS

In this study, a collection of enterococci (n=170) from clinical sources were investigated for their potential to inhibit multiresistant nosocomial enterococci from Iranian hospitals.

RESULTS

Four isolates produced antimicrobial peptides that inhibited all the antibiotic resistant enterococci. This included three Enterococcus faecium isolates producing combinations of enterocin A, B and L50 AB. The most potent antagonism was produced by E. faecalis HO91. Purification and subsequent characterization by MALDI-TOF MS, Edman degradation and DNA-sequencing revealed that the antimicrobial compound was Hiracin. The purified Hiracin was evaluated for antibacterial activity against 12 multiresistant enterococcal isolates from clinical samples. The results demonstrated that Hiracin is highly effective towards enterococci which were resistant even to antibiotics from four distinct classes.

CONCLUSION

The present research addresses Hiracin as a promising alternative to conventional antibiotics in treatment of multiresistant enterococcal infections.