Healthcare-Associated Infections _ ______________________________________________________________
Several risk factors for HAI caused by multidrug-resistant organisms have been identified [77; 78]: • Older age • Underlying disease and severity of illness • Transfer of patients from another institution, especially from a nursing home • Exposure to antimicrobial drugs, especially cephalosporins • Prolonged hospitalization • Gastrointestinal surgery or transplantation • Exposure to invasive devices (urinary catheter, central venous catheter) Antimicrobial-resistant pathogens have been reported to be the source of approximately 14% to 20% of HAIs, and these HAIs are associated with higher rates of morbidity and mortal- ity and greater economic costs than antimicrobial-susceptible infections [42; 79; 80; 81]. The most common drug-resistant HAI is MRSA, which emerged as a significant problem in the 1980s and increased steadily in prevalence, with a rate of approximately 59% of S. aureus infections in U.S. intensive care units (ICUs) in 2004 [78]. Since that time, however, the rate of MRSA associated with HAIs has decreased, most likely because of increased preventive strategies [78; 81]. Overall, the rate of HAIs attrib- utable to antimicrobial-resistant pathogens has not changed substantially since 2010 [81]. According to data on HAIs reported to the NHSN in 2018–2021, 52.1% of the infections were with antimicrobial-resistant phenotypes: MRSA (11.3%); vancomycin-resistant Enterococcus (4.1%); extended-spectrum cephalosporin-resistant Klebsiella pneumoniae and K. oxytoca (8.5%); Escherichia coli (16.2%); Enterobacter spp. (4.1); and carbapenem-resistant Pseudomonas aeruginosa (7.9%) [82]. The discovery of carbapenem-resistant Enterobacteriaceae as a new threat led the CDC to issue a guidance for control of infec- tions with carbapenem-resistant or carbapenemase-producing Enterobacteriaceae in the healthcare setting [83; 84]. Data from the 2021 NHSN network survey report showed that 45.5% of S. aureus isolates were methicillin-resistant, and among E. coli , Enterobacter , and Klebsiella isolates, 4.9% were carbapenem- resistant [82]. The COVID-19 pandemic impacted surveillance for and incidence of HAIs. Although the Centers for Medicare and Medicaid Services implemented the “extraordinary circum- stance exception” (ECE) policy that excused facilities from HAI surveillance and reporting via NHSN for the fourth quarter of 2019 through the second quarter of 2020, between 86% and 88% of acute care hospitals that conducted surveil- lance in the first half of 2019 also performed surveillance and reported data for the first half of 2020. The NHSN analysis of data from 2020 found significant increases in HAIs, including MRSA bacteremia (15% increase), compared with 2019 [85]. As previously stated, the HAI Action Plan set a target for 2020 of a 50% reduction in hospital-onset MRSA [2].
Antimicrobial-resistant HAIs are associated with substantial morbidity and mortality compared with antimicrobial-suscep- tible HAIs, with longer hospital stays (excess of approximately 7 to 13 days), greater attributable mortality (up to 15%), and higher costs (additional $7,000 to $15,000) [78]. Guidelines for the prevention and management of multidrug-resistant pathogens in the hospital setting have been developed by the CDC, SHEA, and IDSA, with the most recent guidelines focusing specifically on the treatment of MRSA [26; 33; 36; 86]. More information on antimicrobial-resistant pathogens is given in the discussions of each type of HAI. In addition, prevention of MRSA infection is addressed in the Infection Control section, as prevention is an important aspect of a healthcare facility’s infection control program. SOURCES OF HAIs In general, the sources of HAIs can be categorized as being related to environmental factors (air, water, architectural design), patient-related factors (age, degree of illness/immune status, length of hospital stay), and iatrogenic factors (invasive procedures, devices, and equipment). ENVIRONMENTAL FACTORS Factors specifically related to the healthcare environment are not common causes of HAIs [18; 87; 88]. However, consid- eration should be given to the prevention of infection with environmental pathogens, such as fungi (e.g., Aspergillus ), bacteria (e.g., Legionella species), or viruses (e.g., varicella) ( Table 4 ). CDC guidelines provide clear recommendations for infection control measures according to several environment- related categories, including air (normal ventilation and filtra- tion, as well as handling during construction or repair), water (water supply systems, ice machines, hydrotherapy tanks and pools), and environmental services (laundry, housekeeping). The infection control program of a facility has oversight of these measures. ENVIRONMENTAL SOURCES OF PATHOGENS IN THE HEALTHCARE SETTING Air Droplets containing micro-organisms can be transmitted in the air, causing infection in patients either directly or indirectly (through contamination of devices or equipment). Cleaning activities, such as sweeping, dry mopping, dusting, or shaking linen, can contribute to the transmission of airborne micro- organisms. Bacteria in the air primarily consist of gram-positive cocci from the skin, and they can be eliminated with appro- priate ventilation and circulation of air [89]. Many airborne viruses, such as influenza and other respiratory viruses and measles, do not carry far from the source; others, such as tuber- culosis and varicella zoster, may be spread over long distances [18]. The most common fungal spore to be transmitted through
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