Intestinal microbiota comprises microbial communities that reside in the gastrointestinal tract and are critical to normal host physiology. Understanding the microbiota's role in host response to invading pathogens will further advance our knowledge of host-microbe interactions. Salmonella enterica serovar Typhimurium was used as a model enteric pathogen to investigate the effect of intestinal microbiota perturbation on host susceptibility to infection. Antibiotics were used to perturb the intestinal microbiota. C57BL/6 mice were treated with clinically relevant doses of streptomycin and vancomycin in drinking water for 2 days, followed by oral infection with Salmonella enterica serovar Typhimurium. Alterations in microbiota composition and numbers were evaluated by fluorescent in situ hybridization, differential plating, and Sybr green staining. Antibiotics had a dose-dependent effect on intestinal microbiota composition. The chosen antibiotic regimen did not significantly alter the total numbers of intestinal bacteria but altered the microbiota composition. Greater preinfection perturbations in the microbiota resulted in increased mouse susceptibility to Salmonella serovar Typhimurium intestinal colonization, greater postinfection alterations in the microbiota, and more severe intestinal pathology. These results suggest that antibiotic treatment alters the balance of the microbial community, which predisposes the host to Salmonella serovar Typhimurium infection, demonstrating the importance of a healthy microbiota in host response to enteric pathogens.

Antibiotic-Induced Perturbations of the Intestinal Microbiota Alter Host Susceptibility to Enteric Infection

Salmonella species, including Salmonella Typhi

The global epidemic of hepatitis B and C is a serious public health problem. Hepatitis B and C are the major causes of chronic liver disease and liver cancer in the world. In the next 10 years, 150,000 people in the United States will die from liver disease or liver cancer associated with chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infections. Today, between 800,000 and 1.4 million people in the United States have chronic hepatitis B and between 2.7 and 3.9 million have chronic hepatitis C. People most at risk for hepatitis B and C often are the least likely to have access to medical services. Reducing the rates of illness and death associated with these diseases will require greater awareness and knowledge among health care workers, improved identification of at-risk people, and improved access to medical care.Hepatitis B is a vaccine-preventable disease. Although federal public health officials recommend that all newborns, children, and at-risk adults receive the vaccine, about 46,000 new acute cases of the HBV infection emerge each year, including 1,000 in infants who acquire the infection during birth from their HBV-positive mothers. Unfortunately, there is no vaccine for hepatitis C, which is transmitted by direct exposure to infectious blood.Hepatitis and Liver Cancer identifies missed opportunities related to the prevention and control of HBV and HCV infections. The book presents ways to reduce the numbers of new HBV and HCV infections and the morbidity and mortality related to chronic viral hepatitis. It identifies priorities for research, policy, and action geared toward federal, state, and local public health officials, stakeholder, and advocacy groups and professional organizations.

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Hepatitis and liver cancer: a national strategy for prevention and control of hepatitis B and C.

This article will focus on the impact caused by chronic viral hepatitis B and C globally and will discuss public health measures that have to be implemented in order to prevent and control these diseases. Chronic viral hepatitis is a major global public health problem, an important cause of morbidity and mortality from sequelae which include chronic hepatitis, cirrhosis and primary liver cancer. Being a 'silent' disease, the contribution of chronic hepatitis to global morbidity and mortality is generally underestimated. Hepatitis B and C prevention and control should seek to reduce both the incidence of new infections and the risk of chronic liver disease. A comprehensive public health prevention programme should include the prevention and detection of HBV and HCV infections, the diagnosis and control of viral hepatitis related chronic liver disease, conducting surveillance and monitoring the effectiveness of prevention activities, and setting up a research agenda.

Chronic viral hepatitis as a public health issue in the world

Population dynamics and antimicrobial resistance of the most prevalent poultry-associated Salmonella serotypes

Hepatitis B vaccine: a seven-year study of adherence to the immunization guidelines and efficacy in HIV-1-positive adults.

Background In July 1999, a rare strain of multidrug-resistant Salmonella enterica serovar Senftenberg was isolated from the sputum of a trauma patient. Over a 6-year period (1999-2005) in northeast Florida, this Salmonella serovar spread to 66 other patients in 16 different healthcare facilities as a result of frequent transfers of patients among institutions. To our knowledge, this is the first outbreak of healthcare-associated infection and colonization with a fluoroquinolone-resistant strain of S. Senftenberg in the United States. Objectives To investigate an outbreak of infection and colonization with an unusual strain of S. Senftenberg and assist with infection control measures. Design A case series, outbreak investigation, and microbiological study of all samples positive for S. Senftenberg on culture. Setting Cases of S. Senftenberg infection and colonization occurred in hospitals and long-term care facilities in 2 counties in northeast Florida. Results The affected patients were mostly elderly persons with multiple medical conditions. They were frequently transferred between healthcare facilities. This Salmonella serovar was capable of long-term colonization of chronically ill patients. All S. Senftenberg isolates tested shared a similar pulsed-field gel electrophoresis (PFGE) pattern. Conclusion A prolonged outbreak of infection and colonization with multidrug-resistant S. Senftenberg was identified in several healthcare facilities throughout the Jacksonville, Florida, area and became established when infection control measures failed. The bacterial agent was capable of long-term colonization in chronically ill patients. Because the dispersal pattern of this strain suggested a breakdown of infection control practices, a multipronged intervention approach was undertaken that included intense education of personnel in the different institutions, interinstitutional cooperation, and transfer paperwork notification.

Michael Sands

Papers

Hepatitis B vaccine: a seven-year study of adherence to the immunization guidelines and efficacy in HIV-1-positive adults.

Outbreak of healthcare-associated infection and colonization with multidrug-resistant Salmonella enterica serovar Senftenberg in Florida.