Infections are a leading cause of mortality worldwide. In 2008, respiratory infections, diarrheal diseases and HIV/AIDS accounted for over 9 million deaths globally . Most infections are caused by bacteria or viruses , which can be transmitted through direct contact with skin or mucous membranes, inhalation of infectious agents, exposure to blood, bodily fluids and secretions, and other methods . To further complicate the problem of infections, the unabated global spread of antimicrobial resistance has resulted in pathogens that are no longer treatable with traditional antibiotics, leading to longer hospital stays and increased patient mortality [4, 5] .
While infections pervade communities and healthcare facilities worldwide, many are preventable [6, 7]. Organizations such as the Centers for Disease Control and Prevention, World Health Organization, Agency for Healthcare Research and Quality, Association for Professionals in Infection Control and Epidemiology, and Society for Healthcare Epidemiology of America are committed to preventing the spread of infectious diseases and have made a wealth of knowledge surrounding infection prevention publicly available.
Antimicrobial resistance occurs when pathogens are no longer sensitive to traditional treatment. While antibiotics have been used to treat infections for the past seventy years, their widespread use has enabled pathogens to adapt, rendering once effective antimicrobials less effective . This is evidenced by the emergence of methicillin-resistant Staphylococcus aureus (MRSA), multi-drug resistant Klebsiella species and Escherichia coli, as well as antibiotic-resistant Streptococcus pneumoniae . Rates of infections associated with organisms such as Clostridium difficile and Klebsiella pneumoniae are increasing due to the emergence of novel strains and biologic variants [9, 10] . Similarly, there is a growing proportion of cases of multidrug-resistant tuberculosis (MDR-TB) globally . See Figure 1. Such resistance causes treatment complications, leading to longer hospital stays, increased costs and greater patient morbidity and mortality [4, 5].
Figure 1. Percentage of MDR-TB among new TB cases, 1994-2010 
Antimicrobial Resistance Key Resources
- Diseases/Pathogens Associated with Antimicrobial Resistance
- Education Campaigns
- Task Forces on Antimicrobial Resistance
Healthcare-associated infections (HAIs) are infections that patients develop while receiving treatment within hospitals, long-term care facilities, ambulatory and rehabilitation centers, nursing homes, and community clinics . Approximately 1 in every 20 hospitalized patients develops an infection , and rates are even higher in long-term care facilities and among particularly vulnerable groups, such as those receiving chronic dialysis or other invasive procedures . About 1.7 million infections occur in hospitals annually, resulting in approximately 99,000 deaths . The four major types of HAIs are catheter-associated urinary tract infections (CAUTI), surgical site infections (SSI), ventilator-associated pneumonia (VAP), and central line-associated bloodstream infections (CLABSI) . See Figure 2. The estimated cost of these infections ranges from $28.4 to $33.8 billion annually in the United States . In recent years, literature has emphasized that HAIs are preventable, namely through provider practice and the promotion of a culture of safety [18-20] .
|Figure 2. Leading Types of Healthcare-Associated Infections 
HAI Key Resources
- Types of HAIs
- Diseases and Organisms in Healthcare Settings
- State-based HAI Prevention and Reporting Laws
- Practice Guidelines for Providers
Community-associated infections remain a leading cause of death worldwide with infections such as influenza, HIV/AIDS, and diarrheal diseases claiming approximately 4.5 million lives each year [1, 21]. In the United States, common community-associated infections include skin infections, such as community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), droplet-caused infections, such as influenza and ingestion-based infections such as norovirus. CA-MRSA has increased seven times from 1999-2006 , and of the 1,518 outbreaks of norovirus between 2010-2011, 22% occurred in the community . See Figure 3. The prevention of community associated infections has been highlighted in the literature; CA-MRSA and norovirus prevention emphasizes good hygiene, such as usage of hand sanitizers and the maintenance of a clean environment [24, 25]; and influenza prevention emphasizes vaccination as well as good hygiene . Of note, community-associated infections have become more complicated as antimicrobial resistant infections, which were once confined to hospital settings, have emerged as significant health problems in communities, perhaps due to shifting care patterns from inpatient to outpatient settings .
|Figure 3. Setting of 1,518 Confirmed Norovirus Outbreaks, U.S., 2010-2011: Long-term Care Facility 59% (889 Outbreaks); Restaurants 8% (123 Outbreaks); Party & Event 7% (99 Outbreaks); Hospital 4% (65 Outbreaks); School 4% (64 Outbreaks); Cruise Ship 4% (55 Outbreaks); Other & Unknown 14% (223 Outbreaks) 
Community-associated Infections Key References
- Community-associated MRSA
- World Health Organization. The top 10 causes of death. 2011 March 20, 2012]; Available from: http://www.who.int/mediacentre/factsheets/fs310/en/index.html.
- Centers for Disease Control and Prevention. Cold and Flu Season: No Reason for Antibiotics. Get Smart Know When Antibiotics Work March 24, 2012]; Available from: http://www.cdc.gov/getsmart/campaign-materials/press_kit/Cold-Flu_Season-508.pdf.
- Centers for Disease Control and Prevention. 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings. March 20, 2012; Available from: http://www.cdc.gov/hicpac/2007IP/2007ip_part3.html.
- O'Fallon, E., et al., Acquisition of multidrug-resistant gram-negative bacteria: incidence and risk factors within a long-term care population. Infect Control Hosp Epidemiol, 2010. 31(11): p. 1148-53.
- World Health Organization, Core components for infection prevention and control programmes: Report of the Second Meeting Informal Network on Infection Prevention and Control in Health Care, 2009: Geneva, Switzerland.
- Centers for Disease Control and Prevention. Pneumonia Can Be Prevented - Vaccines Can Help. 2012 [cited 2012 March 20]; Available from: http://www.cdc.gov/Features/Pneumonia/.
- Centers for Disease Control and Prevention. Healthcare-associated Infections. 2011 September 23, 2011; Available from: http://www.cdc.gov/HAI/bsi/bsi.html.
- Centers for Disease Control and Prevention. Antibiotic/Antimicrobial Resistance. 2010; Available from: http://www.cdc.gov/drugresistance/index.html.
- Freeman, J., et al., The changing epidemiology of Clostridium difficile infections. Clin Microbiol Rev, 2010. 23(3): p. 529-49.
- Meatherall, B.L., et al., Incidence, risk factors, and outcomes of Klebsiella pneumoniae bacteremia. Am J Med, 2009. 122(9): p. 866-73.
- World Health Organization, Antimicrobial resistance, in Fact sheets2012.
- Centers for Disease Control and Prevention. Healthcare-associated Infections. 2010 [cited 2012 March 24]; Available from: http://www.cdc.gov/hai/.
- Centers for Disease Control and Prevention. Heahtcare-associated Infections. The Burden 2010 [cited 2012 March 30]; Available from: http://www.cdc.gov/HAI/burden.html.
- Centers for Disease Control and Prevention. Dialysis Safety. 2011 [cited 2010 March 30]; Available from: http://www.cdc.gov/dialysis/.
- Agency for Healthcare Research and Quality. Ending Healthcare-Associated Infections. 2010 [cited 2012 March 30]; Available from: http://www.ahrq.gov/qual/haicusp.htm.
- U.S. Department of Health & Human Services, HHS Action Plan to Prevent Healthcare-Associated Infections: Introduction, 2010: Washington, D.C.
- Scott, R., The direct medical costs of healthcare-associated infections in U.S. hospitals and the benefits of prevention, D. Division of Healthcare Quality Promotion National Center for Preparedness, and Control of Infectious Diseases,, Editor 2009: Atlanta, GA.
- Centers for Disease Control and Prevention. Healthcare-associated Infections. Winnable Battles 2012 [cited 2012 March 24]; Available from: http://www.cdc.gov/WinnableBattles/HealthcareAssociatedInfections/index.html.
- Umscheid, C., Mitchell, M., Doshi, J., Agarwal, R., Williams, K., Brennan, P., Estimating the Proportion of Healthcare-Associated Infections That Are Reasonably Preventable and the Related Mortality and Costs. Infect Control and Hosp Epidemiolgy, 2011. 32(2).
- Pronovost P, N.D., Berenholtz S, Sinopoli D, Chu H, Cosgrove S, Sexton B, Hyzy R, Welsh R, Roth G, Bander J, Kepros J, Goeschel C., An intervention to decrease catheter-related bloodstream infections in the ICU. N Engl J. Med, 2007. 355(26).
- World Health Organization. Influenza. Media centre 2003 [cited 2012 March 30]; Available from: http://www.who.int/mediacentre/factsheets/2003/fs211/en/.
- Klein, E., Smith, D., Laximinarayan, R., Community-associated Methicillin-Resistant Staphylococcus aureus in Outpatients, United States, 1999-2006. Emerging Infectious Diseases, 2009.
- Centers for Disease Control and Prevention, Surveillance of Norovirus Outbreaks, D.o.V.D. National Center for Immunization and Respiratory Diseases, Editor 2012.
- Centers for Disease Control and Prevention. Personal Prevention of MRSA Skin Infections. MRSA Infections 2010 [cited 2012 March 30]; Available from: http://www.cdc.gov/mrsa/prevent/personal.html.
- National Center for Immunization and Respiratory Diseases. Norovirus. 2010; Available from: http://www.cdc.gov/ncidod/dvrd/revb/gastro/norovirus.htm.
- Centers for Disease Control and Prevention. CDC Says “Take 3” Actions To Fight The Flu. Seasonal Influenza 2011 [cited 2012 March 30]; Available from: http://www.cdc.gov/flu/protect/preventing.htm.
- Siegman-Igra, Y., et al., Reappraisal of community-acquired bacteremia: a proposal of a new classification for the spectrum of acquisition of bacteremia. Clin Infect Dis, 2002. 34(11): p. 1431-9.