Viruses with pandemic potential including H1N1, H5N1, and H5N7 influenza viruses, and severe acute respiratory syndrome (SARS)/Middle East respiratory syndrome (MERS) coronaviruses (CoV) have emerged in recent years. SARS-CoV, MERS-CoV, and influenza virus can survive on surfaces for extended periods, sometimes up to months. Factors influencing the survival of these viruses on surfaces include: strain variation, titre, surface type, suspending medium, mode of deposition, temperature and relative humidity, and the method used to determine the viability of the virus. Environmental sampling has identified contamination in field-settings with SARS-CoV and influenza virus, although the frequent use of molecular detection methods may not necessarily represent the presence of viable virus. The importance of indirect contact transmission (involving contamination of inanimate surfaces) is uncertain compared with other transmission routes, principally direct contact transmission (independent of surface contamination), droplet, and airborne routes. However, influenza virus and SARS-CoV may be shed into the environment and be transferred from environmental surfaces to hands of patients and healthcare providers. Emerging data suggest that MERS-CoV also shares these properties. Once contaminated from the environment, hands can then initiate self-inoculation of mucous membranes of the nose, eyes or mouth. Mathematical and animal models, and intervention studies suggest that contact transmission is the most important route in some scenarios. Infection prevention and control implications include the need for hand hygiene and personal protective equipment to minimize self-contamination and to protect against inoculation of mucosal surfaces and the respiratory tract, and enhanced surface cleaning and disinfection in healthcare settings.

For patients with vancomycin-resistant enterococci in stool, treatment with antianaerobic antibiotics promotes high-density colonization. Limiting the use of such agents in these patients may help decrease the spread of vancomycin-resistant enterococci.

Background. Asymptomatic fecal carriage of Clostridium difficile is common in patients staying in health care facilities, but the importance of asymptomatic carriers with regard to disease transmission is unclear.Methods. We prospectively examined the prevalence of asymptomatic carriage of epidemic North American pulsed-field gel electrophoresis type 1 and nonepidemic toxigenic C. difficile strains among long-term care patients in the context of an outbreak of C. difficile-associated disease and evaluated the frequency of skin and environmental contamination. Molecular typing was performed by pulsed-field gel electrophoresis. Logistic regression was used to assess factors associated with asymptomatic carriage, and a sensitive and specific prediction rule was developed to identify high-risk patients.Results. Thirty-five (51%) of 68 asymptomatic patients were carriers of toxigenic C. difficile, and 13 (37%) of these patients carried epidemic strains. Compared with noncarriers, asymptomatic carriers had higher percentages of skin (61% vs. 19%;) and environmental contamination (59% vs. 24%; ). Eighty-seven percent P p .001 P p .004 of isolates found in skin samples and 58% of isolates found in environmental samples were identical to concurrent isolates found in stool samples. Spores on the skin of asymptomatic patients were easily transferred to investigators' hands. Previous C. difficile-associated disease ( ) and previous antibiotic use ( ) were associated P ! .001 P p .017 with asymptomatic carriage, and the combination of these 2 variables was predictive of asymptomatic carriage (sensitivity, 77%; specificity, 58%; positive predictive value, 66%; negative predictive value, 70%).Conclusions. Our findings suggest that asymptomatic carriers of epidemic and nonepidemic C. difficile strains have the potential to contribute significantly to disease transmission in long-term care facilities. Clinical factors, such as previous C. difficile-associated disease and recent antibiotic use, may be predictive of asymptomatic carriage.

Military medical facilities treating patients injured in Iraq and Afghanistan have identified a large number of multidrug-resistant (MDR)Acinetobacter baumannii isolates. In order to anticipate the impact of these pathogens on patient care, we analyzed the antibiotic resistance genes responsible for the MDR phenotype in Acinetobacter sp. isolates collected from patients at the Walter Reed Army Medical Center (WRAMC). Susceptibility testing, PCR amplification of the genetic determinants of resistance, and clonality were determined. Seventy-five unique patient isolates were included in this study: 53% were from bloodstream infections, 89% were resistant to at least three classes of antibiotics, and 15% were resistant to all nine antibiotics tested. Thirty-seven percent of the isolates were recovered from patients nosocomially infected or colonized at the WRAMC. Sixteen unique resistance genes or gene families and four mobile genetic elements were detected. In addition, this is the first report of bla OXA-58 -like and bla PER -like genes in the U.S. MDR A. baumannii isolates with at least eight identified resistance determinants were recovered from 49 of the 75 patients. Molecular typing revealed multiple clones, with eight major clonal types being nosocomially acquired and with more than 60% of the isolates being related to three pan-European types. This report gives a "snapshot" of the complex genetic background responsible for antimicrobial resistance in Acinetobacter spp. from the WRAMC. Identifying genes associated with the MDR phenotype and defining patterns of transmission serve as a starting point for devising strategies to limit the clinical impact of these serious infections.

The intestinal tract provides an important reservoir for many nosocomial pathogens, including Enterococcus species, Enterobacteriaciae, Clostridium difficile, and Candida species. These organisms share several common risk factors and often coexist in the intestinal tract. Disruption of normal barriers, such as gastric acidity and the indigenous microflora of the colon, facilitates overgrowth of pathogens. Factors such as fecal incontinence and diarrhea contribute to the subsequent dissemination of pathogens into the health care environment. Selective pressure exerted by antibiotics plays a particularly important role in pathogen colonization, and adverse effects associated with these agents often persist beyond the period of treatment. Infection-control measures that are implemented to control individual pathogens may have a positive or negative impact on efforts to control other pathogens that colonize the intestinal tract.