There is still a low level of clinical awareness regarding Legionnaires' disease 25 years after it was first detected. The causative agents, legionellae, are freshwater bacteria with a fascinating ecology. These bacteria are intracellular pathogens of freshwater protozoa and utilize a similar mechanism to infect human phagocytic cells. There have been major advances in delineating the pathogenesis of legionellae through the identification of genes which allow the organism to bypass the endocytic pathways of both protozoan and human cells. Other bacteria that may share this novel infectious process are Coxiella burnetti and Brucella spp. More than 40 species and numerous serogroups of legionellae have been identified. Most diagnostic tests are directed at the species that causes most of the reported human cases of legionellosis, L. pneumophila serogroup 1. For this reason, information on the incidence of human respiratory disease attributable to other species and serogroups of legionellae is lacking. Improvements in diagnostic tests such as the urine antigen assay have inadvertently caused a decrease in the use of culture to detect infection, resulting in incomplete surveillance for legionellosis. Large, focal outbreaks of Legionnaires' disease continue to occur worldwide, and there is a critical need for surveillance for travel-related legionellosis in the United States. There is optimism that newly developed guidelines and water treatment practices can greatly reduce the incidence of this preventable illness

Fresh-pressed, unpreserved apple cider can transmit E coli O157:H7 organisms, which cause severe infections. Risk of transmission can be reduced by washing and brushing apples before pressing, and preserving cider with sodium benzoate. Consumers can reduce their risk by only drinking cider made from apples that have been washed and brushed.

New diagnostic tests and empirical therapy for pneumonia may have important ramifications for the identification, treatment, and control of legionnaires disease (LD). To determine trends in the epidemiology of LD, we analyzed data for 1980-1998 from the passive surveillance system of the Centers for Disease Control and Prevention. During this time period, there were 6757 confirmed cases of LD (median annual number, 360 cases/year). Diagnosis by culture and by direct fluorescent antibody and serologic testing decreased significantly; diagnosis by urine antigen testing increased from 0% to 69%. The frequency of isolates other than Legionella pneumophila serogroup 1 (LP1) decreased from 38% to 4% (P=.003). The case-fatality rate decreased significantly, from 34% to 12% (P<.001) for all cases, from 46% to 14% (P<.0001) for nosocomial cases, and from 26% to 10% (P=.05) for community-acquired cases. LD-related mortality has decreased dramatically. The decrease in culture-based diagnosis limits the recognition of non-LP1 disease and impairs outbreak investigation, because fewer Legionella isolates are provided for further examination.

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Escherichia coli O157:H7 is an increasingly common cause of a variety of illnesses, including bloody diarrhea and the hemolytic uremic syndrome. This emerging infectious agent was first identified in 1982 and has been isolated with increasing frequency since then. This chapter reviews the epidemiology, clinical spectrum, diagnosis, treatment, and prevention of infections with E. coli O157:H7.

A strain of enterohemorrhagic Escherichia coli serotype 0157:H7 isolated from a patient in an apple cider-related outbreak was used to study the fate ofE. coli 0157:H7 in six different lots of unpasteurized apple cider. In addition, the efficacy of two preservatives, 0.1% sodium benzoate and 0.1% potassium sorbate, used separately and in combination was evaluated for antimicrobial effects on the bacterium. Studies were done at 8 or 25°C with ciders having pH values of 3.6 to 4.0. The results revealed that E. coli 0157:H7 populations

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