Culture Compounds which are Able to Increase the Growth and the Production of Bacteriocins by Two Different LABS

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Evaluation of the antimicrobial activity of a blend of monoglycerides against Escherichia coli and Enterococci with multiple drug resistance

Bacterial antibiotic resistance is a natural phenomenon, seriously affecting the treatment of infections. The biggest danger is that current antibiotics are not able to eradicate the resistant strains. In recent years, alternative antibacterial substances are being sought, which can help in these cases. Fatty acids and monoglycerides are known among the natural substances for their antimicrobial properties and, important detail, bacteria do not develop resistance to them. In this work, we studied the antimicrobial effects of a monoglyceride blend against some multi-resistant Enterococci and Escherichia coli strains. Based on literature data, a blend of fatty acids and their monoglycerides was created and its antimicrobial activity was evaluated against 37 strains of E. coli and 17 Enterococci presenting resistance to at least two antibiotics. A different behavior was observed in the two groups of bacteria, proving that alternative substances can be considerate for the potential treatment of multidrug-resistant strains

In vitro evaluation of the amoebicidal activity of rosemary (Rosmarinus officinalis L.) and cloves (Syzygium aromaticum L. Merr. & Perry) essential oils against Acanthamoeba polyphaga trophozoites

Several species of the genus Acanthamoeba cause human diseases. Treatment of infections involves various problems, emphasising the need to develop alternative antiprotozoal agents. We studied the anti-amoebic activity of Essential Oils (EOs), derived from rosemary (Rosmarinus officinalis L.) and cloves (Syzygium aromaticum L. Merr. & Perry), against Acanthamoeba polyphaga strain. The amoebicidal activity of cloves and rosemary EOs was preliminary demonstrated by the morphology change (modifications in the cell shape, the presence of precipitates in the cytoplasm, autophagic vesicles, membrane blends) of the treated trophozoites. The cell-counts, carried out after staining trophozoites with a Trypan blue solution, revealed that both EOs were active in a dose-dependent manner and in relation to the exposure time. This activity was evident after few hours, with encouraging results obtained in particular with cloves EO, able to act at the lower concentrations and after 1 h, probably for its high eugenol content (65.30%)

Antimicrobial resistance and virulence traits in Enterococcus strains isolated from dogs and cats

We investigated presence and prevalence of antibiotic-resistances and other biological characters in enterococci isolated from faeces of healthy dogs and cats because these microorganisms represent important human and veterinary pathogens/opportunists, and a significant burden for healthcare systems. In all samples (n=115) we detected enterococci, with a predominance of Enterococcus faecium (42; 36.5%) and Enterococcus faecalis (36; 31.3%) species, endowed with virulence traits and multidrug-resistance. The two predominant resistance patterns (erythromycin, tetracycline) were examined by polymerase chain reaction for tet and erm genes. Only tetM for tetracycline, and ermA and ermB for erythromycin were detected. PCR for gelatinase gene (gelE) was positive in 62.6% of isolates, but only 26.1% produce gelatinase suggesting the existence of silent genes. efaAfs and efaAfm genes were found in E. faecalis and E. faecium respectively. 89.6% of isolates produced bacteriocin-like substances with a prevailing action against Listeria genus and, among these, 33.9% were positive for the bacteriocin structural genes entA, entL50 or entP. According to our study, pet animals can be considered a reservoir of potentially pathogenic enterococci and we cannot exclude that those microorganisms may be responsible for opportunistic infections in high-risk pet owner

Antimicrobial activity of silver doped fabrics for the production of hospital uniforms

Among several alternatives to control hospital-acquired infections (HAIs), a strategy could be the use of hospital uniforms imbued with antimicrobial substances. For this purpose we evaluated the antibacterial activity of two different silver doped fabrics employed for the production of hospital uniforms. The study was conducted in two-step. In the first the antimicrobial activity was evaluated in vitro against Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 6538, Enterococcus faecalis ATCC 29212. In the second, we tested the total viable counts detected from beginning to end of the work shift on experimental silver doped uniforms worn by doctors, nurses, allied health assistants in different hospital wards. The in vitro tests showed a remarkable antibacterial activity of both silver doped samples (>99.9% reduction within 4h of exposure for Gram-positive and within 24 h for Gram-negative bacteria). The experimental uniforms provided results only slightly in agreement with in vitro data. Even if the increase of total viable counts was somewhat lower for experimental uniforms than traditional ones, significant differences were not observed. Despite the results on the uniforms worn, the addition of silver in fabrics to make medical equipment (supplies) remains an interesting option for HAI control

Conjugation-Mediated Transfer of Antibiotic-Resistance Plasmids Between Enterobacteriaceae in the Digestive Tract of Blaberus craniifer (Blattodea: Blaberidae).

Cockroaches, insects of the order Blattodea, seem to play a crucial role in the possible conjugation-mediated genetic exchanges that occur among bacteria that harbor in the cockroach intestinal tract. The gut of these insects can be thought of as an effective in vivo model for the natural transfer of antimicrobial resistance plasmids among bacteria. In our study, we evaluated the conjugation-mediated horizontal transfer of resistance genes between Escherichia coli and other microorganisms of the same Enterobacteriaceae family within the intestinal tract of Blaberus craniifer Burmeister, 1838 (Blattodea: Blaberidae). Different in vivo mating experiments were performed using E. coli RP4 harboring the RP4 plasmid carrying ampicillin, kanamycin, and tetracycline resistance genes as the donor and E. coli K12 resistant to nalidixic acid or Salmonella enterica serovar Enteritidis IMM39 resistant to streptomycin as the recipients. The RP4 plasmid was successfully transferred to both recipients, producing E. coli K12-RP4 and S. Enteritidis IMM39-RP4 transconjugants. Conjugation frequencies in vivo were similar to those previously observed in vitro. The transfer of the RP4 plasmid in all transconjugants was confirmed by small-scale plasmid isolation and agar gel electrophoresis, suggesting that the intestinal tract of cockroaches is an effective in vivo model for natural gene transfer. Our results confirm that cockroaches allow for the exchange of antimicrobial resistance plasmids among bacteria and may represent a potential reservoir for the dissemination of antibiotic-resistant bacteria in different environments. These findings are particularly significant to human health in the context of health care settings such as hospitals

EXTENDED-SPECTRUM B-LACTAMASE AND PLASMID-MEDIATED AMPC GENES IN SWINE AND GROUND PORK

We investigated the presence of ESBL and AmpC-producing Enterobacteriaceae isolated from 200 rectal swabs of healthy swine and 200 samples of ground pork. Phenotypic testing by using the double synergy differential test (DSDT) for ESBL/ AmpC-positive strains was confirmed by PCR and DNA sequence analysis. The localization of beta-lactamase genes was established by conjugation experiments. ESBL and/or AmpC-producing Enterobacteriaceae was found in 52.2% (95/182) of the isolates collected from rectal swabs and 3% (3/100) of isolates obtained from ground pork samples. Polymerase chain reaction and sequencing confirmed the presence of blaTEM-20, blaTEM-34, blaTEM-52, blaCTX-M-1, blaSHV-12, blaTEM-11SHV-12, blaTEM-201SHV-12, blaCMY-2, blaTEM-11 CMY-2, blaACC-1 and blaACC-2. The conjugation assays yielded positive results, denoting a plasmid localization of the gene

Prevalence and characterization of extended-spectrum beta-lactamase-producing Enterobacteriaceae in food-producing animals in Northern Italy

The aim of this study was to assess the production of extended spectrum beta-lactamases (ESBL) in 56 strains of Enterobacteriaceae, obtained from 100 rectal swabs of farm animals, and to evaluate the horizontal transfer capacity of the genetic determinants of resistance. The ESBL-positive strains were confirmed by phenotypic testing, confirmed by PCR and DNA sequence analysis. The localization of beta-lactamase genes was established by conjugation experiments. Of the 56 analyzed strains, 20 (36%) resulted positive for ESBL production by the double-disk synergy test, and belonged to Escherichia coli 15 (75%) and Klebsiella ozaenae 5 (25%) species. Molecular analysis showed that all ESBL-producing isolates possessed genes encoding for TEM-type enzymes and/or CTX-M. The conjugation assays yielded positive results, thus denoting a plasmidic localization of the genes. This study highlights the high percentage of ESBL-positive Enterobacteriaceae and the mobility of the responsible genes. Gene mobility implies highly negative consequences in terms of drug therapy because of the spread of antibiotic resistance

Prevalence of multi-drug-resistant (MDR) bacteria in air samples from indoor and outdoor environments

The prevalence of multi-drug-resistant (MDR) bacteria in 48 air samples from indoor environments, surgical rooms, dental surgery and waste management plants has been investigated. A total of 280 bacterial strains belonging to different genera were isolated, and the operating rooms were the most contaminated ones (107 isolates), with all the isolates belonging to Gram-positive cocci (51.5 % Micrococcus spp., 48.5 % Staphylococcus spp.). Only 5 % of the isolates was sensitive to all the antibiotics tested, while the remaining strains resulted resistant to three (13 %), four (14 %), five (9 %) and six (10 %) antibiotics. Correlation between the resistance patterns and the environmental source of MDR bacteria isolates also emerged from the present investigation. This study confirms the high presence of antibiotic-resistant bacteria in air samples, finding that represents a threat for the possible transfer of resistance genes to pathogenic bacteria

Anti-listerial activity of coatings entrapping living bacteria

Polyvinyl alcohol (PVOH) based coatings entrapping either living bacteriocin-producer Enterococcus casseliflavus IM 416K1 bacteria or Enterocin 416K1 have been prepared and applied to poly(ethylene terephthalate) (PET) films. The antimicrobial activity of coated PET films was evaluated against Listeria monocytogenes NCTC 10888 by qualitative agar diffusion assays and by direct contact with artificially contaminated food samples (würstel and seasoned cheese) stored at 4 °C and 22 °C. Anti-listerial activity of both coatings was observed for both tests. However, the live-enterococcus doped coatings showed a much more remarkable anti-listerial activity than enterocin doped ones. Interestingly, live-enterococcus doped coatings lead to a strong decrease of L. monocytogenes viable counts even at 22 °C, indicating that they are able to contrast efficiently the fast L. monocytogenes growth occurring at this temperature in würstel samples. In this respect, they can be considered smart coatings, being able to be responsive towards an accidental rise of temperature during food storage. The capability of bacteria to survive for a long time can also assure a long lasting antibacterial activity