Effect of citral and carvacrol on the susceptibility of Listeria monocytogenes and Listeria innocua to antibiotics.

UNLABELLED: The aim of this study was to evaluate the antibiotic susceptibility of Listeria innocua (L. innocua) and Listeria monocytogenes (L. monocytogenes) cells in the presence of citral and carvacrol at sublethal concentrations in an agar medium. The presence of terpenes in the L. monocytogenes and L. innocua culture medium provided a reduction in the minimal inhibitory concentration (MIC) of all the antibiotics tested. These effects were dependent on the concentration of terpenes present in the culture medium. The combination of citral and carvacrol potentiated antibiotic activity by reducing the MIC values of bacitracin and colistin from 32.0 and 128.0 µg ml⁻¹ to 1.0 and 2.0 µg ml⁻¹, respectively. Thus, both Listeria species became more susceptible to these drugs. In this way, the colistin and bacitracin resistance of L. monocytogenes and L. innocua was reversed in the presence of terpenes. Results obtained in this study show that the phytochemicals citral and carvacrol potentiate antibiotic activity, reducing the MIC values of cultured L. monocytogenes and L. innocua. SIGNIFICANCE AND IMPACT OF THE STUDY: Phytochemicals citral and carvacrol potentiate antibiotic activity of erythromycin, bacitracin and colistin by reducing the MIC values of cultured Listeria monocytogenes and Listeria innocua. This effect in reducing the MIC values of the antibiotics tested in both micro-organisms was increased when natural antimicrobials were combined. This finding indicated that the combination among terpenes and antibiotic may contribute in reducing the required dosage of antibiotics due to the possible effect of terpenes on permeation barrier of the micro-organism cell membrane.

A new de novo mutation in a non-hot spot region at the DMD gene in a Mexican family.

In this report we present the analysis of a sporadic case of DMD and his family. In the present case, a deletion of exons 18-47 is presented which predicts abolition of the reading frame and is located between the well-known deletion hot spots of the DMD gene. This mutation was not previously reported in the Leiden database (LOVD). Both MLPA and segregation analysis with short tandem repeat markers elucidated the status of the mother, sister and the younger brother of the proband, who were not carriers of the mutation. This case provides a description of a new pathogenic variant presented as de novo mutation in a DMD patient. Haplotype analysis and complete gene screening may improve genetic counseling in cases of germline mosaicism and de novo mutations.

Synergistic effect of pulsed electric fields and CocoanOX 12% on the inactivation kinetics of Bacillus cereus in a mixed beverage of liquid whole egg and skim milk.

With a view to extending the shelf-life and enhancing the safety of liquid whole egg/skim milk (LWE-SM) mixed beverages, a study was conducted with Bacillus cereus vegetative cells inoculated in skim milk (SM) and LWE-SM beverages, with or without antimicrobial cocoa powder. The beverages were treated with Pulsed Electric Field (PEF) technology and then stored at 5 degrees C for 15 days. The kinetic results were modeled with the Bigelow model, Weibull distribution function, modified Gompertz equation, and Log-logistic models. Maximum inactivation registered a reduction of around 3 log cycles at 40 kV/cm, 360 micros, 20 degrees C in both the SM and LWE-SM beverages. By contrast, in the beverages supplemented with the aforementioned antimicrobial compound, higher inactivation levels were obtained under the same treatment conditions, reaching a 3.30 log(10) cycle reduction. The model affording the best fit for all four beverages was the four-parameter Log-logistic model. After 15 days of storage, the antimicrobial compound lowered Bacillus cereus survival rates in the samples supplemented with CocoanOX 12% by a 4 log cycle reduction, as compared to the untreated samples without CocoanOX 12%. This could indicate that the PEF-antimicrobial combination has a synergistic effect on the bacterial cells under study, increasing their sensitivity to subsequent refrigerated storage.

An epizootic attributable to western equine encephalitis virus infection in emus in Texas.

An epizootic of encephalomyelitis attributable to western equine encephalitis virus was identified in emus (Dromaius novaehollandiae) from several flocks in western Texas in July 1992. Affected emus ranged from 3 months to 3 years old. Morbidity of emus in 8 flocks ranged from 15 to 50%, and 17 of 193 (8.8%) emus died. The diagnosis was confirmed by isolation and characterization of the causative virus and detection of antibody to the virus in emus that were currently ill and emus that had been ill but recovered. Clinical signs varied from mild to severe and included anorexia, lethargy with sternal recumbency, ataxia, muscle tremors, head tilt, unnatural positioning of the head on the back, acute onset of paralysis, and lateral recumbency with paddling. A few emus died without prior evidence of clinical disease. Post-mortem examination revealed 3 to 5 ml of clear pale-yellow pericardial fluid that contained a fibrin clot. Volume of the contents of the proventriculus and ventriculus were less than anticipated. Microscopic examination of numerous tissues revealed multifocal vasculitis with infiltration of plasmacytes, lymphocytes, and a few heterophilic leukocytes. The epizootic developed during a period of unseasonably heavy rainfall that resulted in higher numbers of mosquitoes than was typical for that season of year. A concurrent increase in the number of horses with encephalomyelitis attributable to western equine encephalities virus was not reported.

Clinical and epizootiologic characteristics of dogs seropositive for Borrelia burgdorferi in Texas: 110 cases (1988).

Of 2,409 canine serum samples submitted to the Texas Veterinary Medical Diagnostic Laboratory between Jan 1, 1988 and Dec 31, 1988 and tested by immunofluorescent antibody technique for antibody to Borrelia borgdorferi, 132 (5.5%) had positive results. Clinical and epizootiologic characteristics of seropositive dogs from Texas (n = 110) were examined. Male dogs were more likely than female dogs to be seropositive for B burgdorferi. The most frequent clinical sign of disease described in seropositive dogs was lameness; neurologic, ophthalmologic, dermatologic, renal, and hepatic signs also were reported by referring veterinarians.

Interferon, antibody responses and protection induced by an intranasal infectious bovine rhinotracheitis vaccine.

The interferon and antibody response induced by an intranasal infectious bovine rhinotracheitis vaccine was followed in 22 calves over a nine month period and the ability of these vaccinated calves to withstand challenge with virulent infectious bovine rhinotracheitis virus was assessed. Interferon was detected two to three days post-vaccination and disappeared by the tenth day. Nasal and serum antibodies appeared by day 7 and persisted for nine months. The calves challenged three days postvaccination came down with disease typical of infectious bovine rhinotracheitis, whereas calves challenged three weeks, three months or nine months postvaccination resisted infection.