Efficacy and Synergistic Potential of Cinnamon (Cinnamomum zeylanicum) and Clove (Syzygium aromaticum L. Merr. & Perry) Essential Oils to Control Food-Borne Pathogens in Fresh-Cut Fruits

The presence of microbial pathogens in ready-to-eat produce represents a serious health problem. The antibacterial activity of cinnamon (Cinnamomum zeylanicum) and clove (Syzygium aromaticum L. Merr. & Perry) essential oils (EOs) was determined toward food-borne pathogens by agar disk diffusion and minimum inhibitory concentration (MIC) assays. The growth kinetics of all strains, both in a buffer suspension assay and “on food” in artificially contaminated samples, were also investigated. The two EOs demonstrated a good antibacterial effect both alone and in combination (EO/EO). The use of EO/EO led to a synergistic antibacterial effect, also confirmed by the growth kinetics studies, where the EOs were active after 10 h of incubation (p < 0.0001) at significantly lower concentrations than those when alone. In the “on food” studies performed on artificially contaminated fruit samples stored at 4 °C for 8 days, the greatest killing activity was observed at the end of the trial (8 days) with a reduction of up to 7 log CFU/g compared to the control. These results confirm the good antibacterial activity of the EOs, which were more effective when used in combination. Data from the "on food" studies suggest cinnamon and clove essential oils, traditionally used in the food industry, as a possible natural alternative to chemical additives. Keywords: cinnamon and clove essential oils; synergistic activity; food-borne pathogens; fresh-cut fruit; bio-preservatio

Molecular Characterization of Klebsiella Pneumonia in Clinical Isolates with High Resistance toward Carbapenemases

Carbapenem-resistant Enterobacteriaceae (CRE) is spreading in worldwide and has become endemic in several countries, including Italy . In this report we present the phenotypic and molecular characterizations of KPC-producing carbapenem-resistant K. pneumoniae clinical isolates in an Italian hospital

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

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

Study of five penicillinase producing Neisseria gonorrhoeae isolated in Italy.

Five penicillinase producing Neisseria gonorrhoeae (PPNG) were isolated from urethral specimens of men admitted to the "Santa Chiara" Hospital (Trento, Italy). All strains proved to be resistant to penicillin and ampicillin, and sensitive to cefuroxime, erythromycin, tetracycline, spectinomycin, nalidixic acid and ciprofloxacin. PPNG plasmid profiles showed that four of the isolates carried the 3.2 MDa "Africa" plasmid and one the 4.5 MDa "Asia" plasmid, the two well-known phenotypes reported in the USA and Europe as well as in Asian and African countries. Membrane matings were performed using N. gonorrhoeae carrying the 24.5 MDa conjugative plasmid as donors and E. coli K12 J 53 as recipient. The transfer of beta-lactamic antibiotic resistance was supported by the presence of 4.5 or 3.2 MDa plasmid bands and by beta-lactamase production in the transconjugants. Restriction analysis of Asian and African plasmids is reported

Enterocin 416K1, an antilisterial bacteriocin produced by Enterococcus casseliflavus IM 416K1 isolated from Italian sausages.

Enterococci (118) from Italian sausages were tested for the production of antimicrobial substances. Of these, 7.6\% showed antibacterial activity against one or several closely related microorganisms used as indicators. Enterococcus casseliflavus IM 416K1 in particular produced a bacteriocin (Enterocin 416K1) with strong anti-listerial antagonistic activity. The bacteriocin withstood heating at 90 degrees C for 120 min and storage at 4 degrees C for 6 months. The mode of action was identified as bactericidal. The crude activity of Enterocin 416K1 was linked to a molecule with an apparent molecular weight smaller than 5 kDa. Plasmid analysis of E. casseliflavus IM 416K1 revealed the presence of four plasmids with different molecular weights (34, 11, 7 and 3.3 MDa). All the Bac- variants produced by curing experiments showed loss of the single plasmid of 34 MDa. Bacteriocin activity and immunity production may be linked to genes located on that same plasmid

Study of two bacteriocins produced by Enterococcus casseliflavus and Ent. faecalis.

The antimicrobial activity of two plasmid-borne bacteriocins produced by Enterococcus casseliflavus IM 416K1 and Ent. faecalis IM 388C and their mating transferability were studied.Both bacteriocins showed antibacterial activity against taxonomically related micro-organisms and Listeria monocytogenes but differ for heat sensitivity, antimicrobial titre, molecular size and class of affiliation. The transferability by mating of the antibacterial properties from producers to Enterococcus faecalis JH2-2 revealed that the bacteriocin-phenotype was linked in both strains to genes located on a 34 MDa plasmid. This result was confirmed by loss of antibacterial activity and immunity after curing treatment.Restriction analysis has shown a different profile of the two conjugative plasmids. Enterocin 416K1 and Enterocin 388C could represent natural antilisterial agents to use in food technology.The transferability of the 34 MDa conjugative plasmids might be considered a possibility for the study of bacteriocins expression in bacterial hosts different from the native strains