Considerations on the isolation of Listeria monocytogenes and other Listeria spp. in food products.

Listeria monocytogenes, a Gram positive bacillus, is well adapted for survival as a saprophyte in soil and decaying vegetation, but also able to cause serious infections, due to its ability of intracellular multiplication and meningeal and placental dissemination. A total number of 43 Listeria spp. strains isolated from food were investigated. Bacterial identification was performed according to standard methodology, based on: Gram staining affinity, morphology, culture aspects on blood agar (examined in oblique light), catalase test, beta/hemolysis (on sheep blood agar), CAMP test and carbohydrates breakdown, i.e., trehalose, mannitol, mannose, rhamnoze, xylose. Out of the 43 analyzed strains, the biochemical and serological assay evidenced: 10 strains of L.monocytogenes (8 belonging to serotype la and 2 strains to the serotype 4 b), 27 of L. innocua, 2 of L. grayi and 4 of L. welshimeri. L. innoqua was the most frequently identified species. L. monocytogenes strains typing confirms that the serotype la is most commonly found in food and serotype 4b was detected in imported foods. This observation has an epidemiological importance for our country.

Antimicrobial activity of copper and silver nanofilms on nosocomial bacterial species.

Contaminated surfaces are possible vehicles in infection transmission. It is known that both Copper (Cu) and Silver (Ag) efficiently inactivate microbes by direct contact. Aiming at using these metals for benefitting from their antimicrobial effect, but to avoid subsequent toxic effects, we evaluated the antimicrobial activity of nanometric thin Silver and Copper films covering less expensive materials. Using a modified version of the Japan Industrial Standard JIS Z 2801:2000, we demonstrated the antimicrobial activity of the surfaces covered with metal ions nanofilms on microorganisms possibly involved in nosocomial infections and on Bacillus anthracis, bacteria with possible implication in bioterrorist attacks. Copper covered surfaces proved to have better antimicrobial activity than Silver surfaces. Silver covered surfaces showed better activity on Gram negative bacteria than on Gram positive cocci. Going deeper with studies on antimicrobial effects using new methods with better direct and/or functional discriminatory capacity is needed in order to provide additional information on the mechanisms of Silver and Copper nanofilms antimicrobial activity.

Susceptibility to antibiotics of Bacillus anthracis strains isolated in Romania.

A number of 21 B. anthracis strains isolated from 16 pustules, 2 blood cultures and 3 cerebrospinal fluids during 2000-2004 were studied for their susceptibility to antibiotics. The antibiosusceptibility testing was performed by disk diffusion method, on Mueller-Hinton agar medium. Two of the studied strains exhibited resistance to penicillins, considered until not long ago as antimicrobial agents of choice for the treatment of anthrax infection. The penicillin resistance explained the difficulties encountered during the treatment of these two cases as well as the fatal evolution in one of them. Both penicillin-resistant strains were subsequently tested, by using "in agar" antibiotic dilution method, in order to determine the minimum inhibitory concentrations (MIC) of the respective strains to penicillin G by the help of a serial antibiotic dilution from 16 microg/ml to 0.0075 microg/ml. The MIC values were 0.5 microg/ml and 4 microg/ml respectively, whereas in case of the standard B. anthracis 34F2 Sterne strain was < 0.015 microg/ml. All the 21 B. anthracis tested strains exhibited resistance to the IIIrd generation cephalosporins, as well as to TMP/STX, but were sensitive to tetracyclines and fluoroquinolones, these sensitivity aspects coming into agreement with the literature data. The strains proved to be also susceptible as follows: 13 strains to macrolides, 15 to rifampicin, 16 to chloramphenicol and all 21 to gentamycin; the last antibiotic can be used in association with fluoroquinolones in the treatment of B. anthracis infections. Fluoroquinolones (i.e. ciprofloxacin) become drugs of choice for the treatment of B. anthracis infections if early administered (within the first 24 hrs), in advance of the germ invasion into the lymph system and septicemia, preventing in this way the bacterial multiplication and production of edemathogenic and lethal toxins.

[Epidemiology studies regarding anthrax epidemic in Romania]. / Studii epidemiologice în epidemia de antrax din România.

Antrax infection, a major bacterial zoonosis caused by B. anthracis, affects animals, particulary the herbivores. The infection can be accidentally transmitted to man, in whom it has two forms. Cutaneous anthrax, more frequently encountered (95%), the transmission being favoured by the contact with contaminated animal or, after the sacrifice of the animal, with various contaminated products (skin, wool, hair, especially of goat, as well as bones, meat, blood); the evolution is favourable following treatment. Internal (visceral)--pulmonary, gastro-intestinal, meningo-encephalytic--anthrax causes quasi-total mortality, despite treatment. Transmission is conditioned by the presence of sporulated forms. The bacteriological diagnosis is based on the detection of the germ on smears or cultures for various pathological specimens (skin lesions, blood, tissues, exudates, c.s.f., sputum, etc), rapid results being obtained by immunofluorescence. The serological diagnosis is indicated by the elevated titer of antibodies, detectable by immunological methods (ELISA). 81 pathological specimens and 16 soil samples suspected of B. anthracis were received by our laboratory in 2000 and were investigated for their morpho-cultural characteristics, under the microscope and using pathogenecity tests. Of the total number of samples investigated, B. anthracis was confirmed in 12 (12.37%) cases.