MICs of Mutacin B-Ny266, Nisin A, Vancomycin, and Oxacillin against Bacterial Pathogens (original) (raw)
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Combined effect of bacteriocins on the survival of various Listeria species in broth and meat system
Current microbiology, 2000
The antilisterial efficiency of three bacteriocins from lactic acid bacteria, lactocin 705 (produced by L. casei CRL705, 17000 AU/ml), enterocin CRL35 (produced by E. faecium CRL35, 17000 AU/ml), and nisin (2000 IU/ml), was tested in broth, individually and in combination against Listeria monocytogenes and Listeria innocua. Both Listeria species showed an initial decrease in viable counts followed by the regrowth of the survivors after 1 h in the presence of each bacteriocin. A greater antilisterial effect was observed when the bacteriocins were combined in pairs, maximal inhibition being reached when nisin was involved. When a mix of the three bacteriocins was used, no survivors were observed after 24 h of incubation. Similar results were obtained when the bacteriocin combinations were tested in a meat system, indicating that the use of more than one LAB bacteriocin in combination may be effective in preventing the spontaneous emergence of a bacteriocin-resistant Listeria population.
Antimicrobial Agents and Chemotherapy, 1985
Antibiotic susceptibility was studied in 175 clinical isolates of Listeria monocytogenes. There were no major changes in the susceptibility of strains between 1958 and 1982. Benzylpenicillin and ampicillin had MICs for 90% of the strains (MIC90) of 0.5 micrograms/ml. Gentamicin also had good activity against L. monocytogenes, with an MIC90 of 1.0 microgram/ml. All the new beta-lactamase-stable cephalosporins tested had relatively poor activity against L. monocytogenes. Of the bacteriostatic antibiotics, trimethoprim had by far the lowest MIC90 (0.06 microgram/ml), and in combination with sulfamethoxazole (co-trimoxazole), it had an MIC90 of 0.5 microgram/ml. Both erythromycin and doxycycline had low MIC90s (0.25 microgram/ml).
2013
Results: Isolates were identified as L monocytogenes (259; 82.5%), L ivanovii (2; 0.6%), and Listeria species (53; 16.9%). Distribution of L monocytogenes serotypes: 4a/4c (0.4%), 4b (11.2%), 4d/4e (14%), 4b/4d/4e (9.3%), 1/2a (26.3%), 3a (7.7%), 1/2a/3a (6.2%), 1/2b/3b (1.2%), 1/2c (5%), 3c (1.2%), and 1/2c/3c (5.4%). Thirty-two L monocytogenes isolates (12.4%) were not typeable by PCR-REA, suggesting the possibility of serotypes 4ab/7. Susceptibility was 84.2% to 100% for most antimicrobials. Major resistance (R) and intermediate (I) susceptibility were found for clindamycin (R = 36.7%, I = 39.8% for L monocytogenes; R = 100% for L ivanovii; and R = 14%, I = 86% for Listeria species). Drugs of choice for treatment of human listeriosis (penicillin, ampicillin, and trimethoprim-sulfamethoxazole) remained effective; 1.2% of L monocytogenes were s-lactam resistant. Multidrug resistance was found only in L monocytogenes (26.6%) and Listeria species (26.4%), with (clindamycinI or R -ery...
Susceptibilities of Listeria species isolated from food to nine antimicrobial agents
Antimicrobial Agents and Chemotherapy, 1994
The agar dilution method was used to determine the activities of gentamicin, erythromycin, streptomycin, chloramphenicol, ampicillin, sulfamethazine, cephalothin, penicillin G, and tetracycline against 73 strains belonging to the genus Listeria (L. innocua, L. seeligeri, and L. monocytogenes). All strains were isolated from raw milk, cheese, the dairy processing plant, poultry, and the poultry slaughterhouse. Gentamicin, ampicillin, and erythromycin, of which the MICs for 90% of the strains tested for all three species were .5.96 ,ug/ml, were found to be the most active agents studied. Most of the L. innocua strains isolated from poultry and the poultry slaughterhouse were resistant to tetracycline. Listeriosis is an infectious disease which affects both humans and animals. Most cases of human listeriosis appear to be
Listeria monocytogenes Monographic Study
usab-tm.ro
Listeria monocytogenes is a ubiquitous bacteria with a remarkable resistance in discordant condition which produce listeriosis, an infectious disease that affects multiple domestic and wild animals' species, but also humans. Receptive to listeriosis are the majority of domestic or wild mammals and birds, in the last years being registered an increase of receptivity in humans. The concept of listeriosis in human pathology, a disease caused by eating or drinking contaminated food and water, appeared for the first time in 1981, during an outbreak in Canada with seven cases in adults and 34 cases of maternalfetal listeriosis. The alimentary origin of human listeriosis can be easily explained if considered some general characteristics of the bacteria. Thus, resistance in various conditions, especially at lower temperatures, justifies its dissemination and food contamination, particularly when is conserved by refrigeration. Also, L. monocytogenes has a significant presence in alimentary products. Some studies showed that 4% of the milk products, 29% of the meat products, 5% of the vegetable products and 26% of the products obtained from fishes and shell fishes are positive for L. monocytogenes, which allows us to say that battle against these bacteria is a war against microbial contamination.
Bacteriocin-producing lactic acid bacteria were isolated from 34 samples of dairy products. Nine bacteriocin producers were phenotypically and genotypically identified asEnterococcus faecium.By means of PCR-techniques, enterocin A was characterised in all of the nine bacteriocin-producing Enterococcusisolates. Enterocin-producing lactic acid bacteria were the most abundant in dairy products collected from different areas in Iran. Maximum bacteriocin production by Enterococcus faecium strains was detected in the stationary phase of growth. Bacteriocins produced by all isolates were found to have anti-listerial activity in sterile milk. The purified bacteriocins were identified as <6.5 kDa peptide by sodium dodecyl sulphate-polyacrylamide gel (SDS-PAGE). The molecular weights of bacteriocins were found to be the same in all strains. This bacteriocin might be useful as a natural preservative.
Characterization of antimicrobial resistance of foodborne Listeria monocytogenes
2009
The objective of this study was to evaluate the susceptibility of 120 Listeria monocytogenes strains isolated from food and food-processing environments to 19 antibiotics currently used in veterinary and human therapy. Susceptibility tests were performed by using the automated VITEK2 system. Apart from penicillin, ampicillin and trimethoprim-sulfamethoxazole, for which clinical breakpoints for Listeria susceptibility testing are defined according to the Clinical and Laboratory Standard Institute (CLSI), in the present study the CLSI criteria for staphylococci were applied. Among the 120 tested strains, 14 (11.7%) displayed resistance to at least one antibiotic. In particular, resistance to one antibiotic was more common than multiple resistance, i.e., 10 (8.3%) isolates were resistant to one antibiotic, 3 (2.5%) to two antibiotics and one (0.8%) to five antibiotics. Resistance to clindamycin was the most common, followed by linezolid, ciprofloxacin, ampicillin and rifampicin, trimethoprim/sulphamethoxazole and, finally, vancomycin and tetracycline. This study shows that L. monocytogenes strains from food and food-processing environments are susceptible to the antibiotics commonly used in veterinary and human listeriosis treatment. Considering that L. monocytogenes is slowly becoming antibiotic resistant, a continued surveillance of emerging antimicrobial resistance of this pathogen is important to ensure effective treatment of human listeriosis. These data are useful in improving background data on antibiotic resistance of strains isolated from food and food environment.