No abstract

Human Salmonella infections are common; most infections are self-limiting, however severe disease may occur. Antimicrobial agents, while not essential for the treatment of Salmonella gastroenteritis, are essential for the treatment of thousands of patients each year with invasive infections. Fluoroquinolones and third-generation cephalosporins are the drugs-of-choice for invasive Salmonella infections in humans; alternative antimicrobial choices are limited by increasing antimicrobial resistance, limited efficacy, and less desirable pharmacodynamic properties. Antimicrobial-resistant Salmonella results from the use of antimicrobial agents in food animals, and these antimicrobial resistant Salmonella are subsequently transmitted to humans, usually through the food supply. The antimicrobial resistance patterns of isolates collected from persons with Salmonella infections show more resistance to antimicrobial agents used in agriculture than to antimicrobial agents used for the treatment of Salmonella infections in humans. Because of the adverse health consequences in humans and animals associated with the increasing prevalence of antimicrobial-resistant Salmonella, there is an urgent need to emphasize non-antimicrobial infection control strategies, such as improved sanitation and hygiene, to develop guidelines for the prudent usage of antimicrobial agents, and establishment of adequate public health safeguards to minimize the development and dissemination of antimicrobial resistance and dissemination of Salmonella resistant to these agents.

Drug-susceptible and drug-resistant isolates of Mycobacterium tuberculosis were recovered from 2 patients, 1 with isoniazid-resistant tuberculosis (patient 1) and another with multidrug-resistant tuberculosis (patient 2). An investigation included patient interviews, record reviews, and genotyping of isolates. Both patients worked in a medical-waste processing plant. Transmission from waste was responsible for at least the multidrug-resistant infection. We found no evidence that specimens were switched or that cross-contamination of cultures occurred. For patient 1, susceptible and isoniazid-resistant isolates, collected 15 days apart, had 21 and 19 restriction fragments containing IS6110, 18 of which were common to both. For patient 2, a single isolate contained both drug-susceptible and multidrug-resistant colonies, demonstrating 10 and 11 different restriction fragments, respectively. These observations indicate that simultaneous infections with multiple strains of M. tuberculosis occur in immunocompetent hosts and may be responsible for conflicting drug-susceptibility results, though the circumstances of infections in these cases may have been unusual.