Screening of the antibacterial effects of a variety of essential oils on microorganisms responsible for respiratory infections.

The aim of this study was to examine the cytotoxicity and the antibacterial effects of a variety of essential oils on major respiratory tract pathogens. The cytotoxicity of 13 essential oils was evaluated on Vero cells. The antibacterial activity was evaluated by the Kirby Bauer paper method, minimum inhibitory and bactericidal concentration against Streptococcus pyogenes, agalactiae, pneumoniae and Klebsiella pneumoniae, Haemophilus influenzae, Staphylococcus aureus and Stenotrophomonas maltophilia isolated from clinical specimens. The antibiotic sensitivity of these isolates was examined. Some oils showed inhibition of bacterial growth against most of the organisms examined. Cinnamon and thyme showed the strongest action followed by clove. The results reported in this paper indicate that thyme can be considered as a potential antimicrobial agent for the treatment of some respiratory tract infections in man.

Comparison of culture and immunoassay for detection of Escherichia coli O157 in raw minced meat and hamburger.

Verocytotoxin-producing Escherichia coli O157 (VTEC) is an important food-borne pathogen of humans. The serious complications of VTEC infection and the established reservoir of VTEC in cattle used for mass food production are a public health concern. In this study 500 samples of hamburger and minced meat were examined for presence of E. coli O157. For E. coli detection, Tryptic Soy Broth supplemented (with novobiocin and bile salts) and Sorbitol Mc Conkey agar were used; an automated rapid enzyme linked fluorescent immunoassay (VIDAS E. coli O157) was also evaluated. E. coli O157 was found in 5 samples of hamburger, 2 strains were found to be positive for verocytotoxin production on Vero cells.

Inhibitory activity of spices and essential oils on psychrotrophic bacteria.

This study was designed to evaluate "in vitro" the inhibitory effects of spices and essential oils on the growth of psycrotrophic food-borne bacteria: Aeromonas hydrophila, Listeria monocytogenes and Yersinia enterocolitica. The sensitivity to nine spices and their oils (chilli, cinnamon, cloves, ginger, nutmeg, oregano, rosemary, sage, thyme) was studied. Antibacterial activity was evaluated on liquid and solid medium. Spices: 1% concentration of each spice was added separately to Triptic Soy Broth and then inoculated to contain 10(8)/ml organism and held to 4 degrees C for 7 days. Populations of test organism were determined on Triptic Soy Agar. Oils: Inhibition of growth was tested by using the paper disc agar diffusion method (at 35, 20 and 4 degrees C) and measuring their inhibition zone. MIC was determined by the broth microdilution method. Some culinary spices produce antibacterial activity: inhibition of growth ranged from complete (cinnamon and cloves against A. hydrophila) to no inhibition. Antibacterial inhibition zone ranged from 8 mm to 45 mm: thyme essential oil showed the greatest inhibition against A. hydrophila.

Evaluation of a vero cell toxicity test to detect EHEC infection.

An epidemiologic investigation was carried out in Modena (Italy) to evaluate the prevalence of faecal VEROtoxin (FVT) in diarrhoeal stool specimens. One thousand and sixty-six stool specimens, submitted to the Clinical Microbiology Laboratory of the University Hospital of Modena, were collected and faecal filtrates tested for neutralizable cytotoxin by a toxicity test on VERO cells. Cytopathic effect on VERO cells was produced by 301 stool specimens (28%); neutralizable VT was detected in 40 (13%) out of 301 positive samples (3.7% of 1066 specimens). The prevalent FVT type was VT2 (50%), followed by VT1 (32.5%) and VT1+2 (17.5%). We evaluated an assay that detects both VTs directly from stool specimens to demonstrate that enterohemorrhagic strains (EHEC) should be considerated a causative agent of sporadic non-bloody diarrhoea. Our results suggest that toxin neutralization assay is a sensitive and specific technique and may be used as an alternative method to diagnose diarrhoeal infections caused by EHEC.

[Presence of bacteria belonging to the genus Yersinia in surface and ground water]. / Presenza di batteri appartenenti al genere Yersinia in acque superficiali e di falda.

Yersinia strains in surface waters and ground waters. After reviewing national and international writing regarding the prevalence of yersiniae in surface waters and ground waters, the Authors report data about a research carried out in the province of Modena (Italy). Over a period of 16 months (february 1986-may 1987) 89 water samples were examined (55 samples collected from rivers and streams and 34 from wells). During every sampling session two samples were collected; one was taken in a sterile bottle (1000 cm3), one by means of the Moore tampon, allowed to float in the stream for 48 h. Yersinia strains were isolated from 37% of the water samples; 33 samples gave a positive result. Forty one strains were isolated on the whole; filtration method by Millipore membrane appeared the most suitable technique in order to obtain a good recovery rate. Y. enterocolitica appeared the most represented species (43.8%), followed by Y. intermedia (21.9%) and Y. fredericksenii (17.1%). Five atypical strains were isolated, while no strain belonging to the species Y. kristensenii has been evidenced. No relevant difference in Yersinia presence appeared between surface waters and ground waters. No human pathogenic strain has been evidenced and all the isolates appeared belonging to environmental biogroups, serogroups and phage-types.

[Evaluation of the immunoenzymatic method for the study of rubella virus antibodies in relation to the traditional hemagglutination-inhibition test]. / Valutazione del metodo immunoenzimatico per la ricerca degli anticorpi anti-virus rubeolico in rapporto al tradizionale test di emoagglutinoinibizione.

The authors compare enzyme immunoassay for rubella virus antibodies (ELISA) with a customary test, hemoagglutino-inhibition test. 392 sera samples were collected from healthy boys and girls; 304 girls had been vaccinated five years before. The authors research sensitivity and specificity of ELISA in comparison with hemoagglutino-inhibition test; ELISA proves to have a high degree of sensitivity, but it is less specific than hemoagglutino-inhibition test. This underlines the possibility to have false positive results from ELISA which appears a very useful test for epidemiological screenings, but less reliable for the diagnosis of recent rubella infections. As ELISA results are usually expressed in Optical Density values, and hemoagglutino-inhibition test results in antibodies dilutions, the authors have performed a graphic analysis; Optical Density values were evaluated in correspondence to the log2 of reciprocal dilutions of hemoagglutino-inhibition test positives. There is evidence of a linear correlation; in this way one can transform ELISA values in their correspondent antibodies dilutions, which are easily understood by general physicians.

[Immune status of a school-population sample 5 years after antirubella vaccination]. / Stato immunitario di un campione di popolazione scolastica a 5 anni dalla vaccinazione antirosolia.

Hemagglutination inhibition (HI) test for rubella immunity were performed on sera collected from 830 subjects five years after rubella vaccination. 629 sera were belonging to vaccinated school- girls and 201 to school-boys and girls not submitted to vaccination. The incidence of seronegativity was significantly lower (1%) in vaccinated girls compared to untreated (12%). The data presented indicate that rubella vaccination affords a persistent antibody protection even thought the antibody titre is low.

[The incidence and variation of transferable antibiotic-resistance in Salmonella strains isolated in Modena in the years 1975-1977 (author's transl)]. / Incidenza e comportamento della antibiotico-resistenza trasferibile in ceppi di Salmonella isolati a Modena nel triennio 1975-1977.

The antibiotic-resistance of 450 strains of Salmonella isolated by the Microbiology Unit of the hospital of Modena during the years 1975-1977 was examined. During the study, the following antibiotics were assayed: ampicillin, kanamycine, tetracycline, chloramphenicol, streptomycin, sulfonamides, trimethoprim, tobramycin, gentamicin and nalidixic acid. The transfer capacity of antibiotic-resistance was measured by the double conjugation of E. coli K-12. During the period studied, a remarkable reduction was noted in those strains with multiple resistance (3 or more elements) decreasing from 72.9% in 1975 to 23.5% in 1977. These phenomena are due to the decrease of the serum-type wien during the years under study. Antibiotic-resistance demonstrated itself most frequently to streptomycin and tetracycline; and chloramphenicol-resistance showed the highest transfer capacity (97.2%).