By means of the enrichment culture technique, a mixed population of microorganisms was obtained which catalyzed the dispersion of crude oil in supplemented sea water. From this enrichment culture, eight pure cultures were isolated and studied. Only one of the isolates (RAG-1) brought about a significant dispersion of crude oil. RAG-1 has been tentatively characterized as a member of the genus Arthrobacter. The other seven isolates gave rise to colonies on supplemented oil agar, but were neither able to disperse oil nor to stimulate the dispersion catalyzed by RAG-1. The dispersion of crude oil by either RAG-1 or the enrichment culture was absolutely dependent on exogenous sources of nitrogen and phosphorous and completely inhibited by 10-2 M azide. The increase in cell number of RAG-1 was directly proportional to the concentration of crude oil added to the medium over the range 0.05 to 1.0 mg/ml. Within this linear region, 1.0 mg of crude oil yielded 9 x 107 cells and approximately 65% of the oil was converted into a nonbenzene extractable form. Accompanying the emulsification was a decrease in the pH from 7.6 to 5.0. Acidic conditions, however, were neither necessary nor sufficient for oil dispersion. When sea water was supplemented with 0.029 mm K2HPO4 and 3.8 mm (NH4)2SO4 and inoculated with RAG-1, oil dispersion occurred within 1 day. This dispersion could also be brought about by the supernatant following separation of the cells from the medium. Similarly, the supernatant obtained following growth of RAG-1 on hexadecane was capable of emulsifying crude oil in 60 min.

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The aim of the present study was to assess the recent trends in the epidemiology of non-typhoid Salmonella in Israel using a sentinel laboratory-based surveillance network. Between 1999 and 2009, 8758 Salmonella stool isolates were reported by five sentinel laboratories. There was a significant decrease in the incidence rate of Salmonella isolates from 70·5/100,000 in 1999 to 21·6/100,000 in 2005 followed by a slight increase to 30·3/100,000 in 2009. Of all Salmonella, 64·3% were isolated from children in the 0-4 years age group. Up to 2008, S. Enteritidis was the most prevalent serotype and in 2009 S. Infantis emerged as the most common Salmonella serotype. The decrease in the incidence of S. Enteritidis and S. Typhimurium and increase in S. Infantis among humans were associated with a similar trend among breeding flocks, which followed significant preventive interventions conducted against S. Enteritidis and S. Typhimurium infections in poultry. Tight surveillance and education of food handlers and consumers should be enhanced to reduce the foodborne transmission of Salmonella in Israel.

Extraintestinal disease occurs in 5-8% of non-typhoid Salmonella enterica (NTS) infections and is more likely to be associated with hospitalization and death. The study examined the epidemiology of extraintestinal NTS infections in Israel and the possible effects of patients' age and sex. NTS isolates passively submitted to the National Salmonella Reference Center during 1996-2006 were the source for the study cohort. Poisson regression models were used to assess incidence trends over the study years and to evaluate the effects of patients' age and sex on the incidence of extraintestinal NTS manifestations. A total of 36,822 stool and 1,415 (3.7%) patient-unique NTS isolates from blood (74.1%), urine (18.3%), and other sources (3.7%) were studied. Serotypes Enteritidis, Virchow, and Typhimurium accounted for 66.3% of the isolates. Analysis showed a highly significant quadratic (U-shaped) relationship between patients' age and the incidence of extraintestinal isolation (p < 0.001), with increasing risk in the two extremes of age. Differences between the incidence of blood and urine sources were significant in patients <10 and >or=60 years old (relative risk [RR] = 5.88, 95% confidence interval [CI] 3.36-10.30, p < 0.001 and RR = 1.66, 95% CI 1.09-2.53, p = 0.017, respectively). Males >or=60 years of age were more likely than females of the same age to have bacteremia (RR = 1.90, 95% CI 1.39-2.61, p > 0.001) and less likely to have urinary NTS isolation (RR = 0.50, 95% CI 0.28-0.89, p = 0.018). Serotype Virchow had the highest incidence in patients <10 years of age, while serotype Enteritidis had the highest incidence in patients >or=60 years old. The study revealed a complex effect of patients' age and sex on the epidemiology of extraintestinal NTS manifestations.

This study outlines the unique epidemiology of Salmonella enterica serotype Virchow in Israel. Between 1997 and 2002, the overall incidence of non-typhoid Salmonella enterica (NTS) decreased from 69.3 to 53.3 infections/100,000 population, but the incidence of S. Virchow increased (from 7.2 to 9.1 infections/100,000). Since 2000, S. Virchow has become the second-ranking NTS isolate, accounting for 17% and 27% of all stool and blood NTS isolates, respectively. Infants aged < 1 year had the highest incidence of isolation from stools (92.8/100,000). The incidence of isolation from blood was highest for infants aged <1 year (4.4/100,000). Only 6% of isolates were susceptible to all ten antibiotic agents tested; 34% were resistant to one agent, 54% to one to three agents, and 40% to four to six agents. A high proportion of the tested isolates were resistant to nalidixic acid (89%), streptomycin (56%), tetracycline (43%), trimethoprim-sulphamethoxazole (38%) and chloramphenicol (28%), but none to ciprofloxacin or ceftriaxone. Pulsed-field gel electrophoresis revealed two closely related clusters, each containing a predominant pulsotype. Coupled with its invasive propensity, the increasing incidence of highly resistant S. Virchow in Israel is of real concern. Future research should focus on the sources of S. Virchow in the food chain in order to institute effective control measures.