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Improving Control of Health Care-associated Infections
From the University of Wisconsin School of Medicine and Public Health’s Update on Infectious Diseases
Dennis G. Maki, MD, Ovid O. Meyer Professor of Medicine, Section of Infectious Diseases, University of Wisconsin School of Medicine and Public Health, Attending Physician, Center for Trauma and Life Support, and Hospital Epidemiologist, University of Wisconsin Hospital and Clinics, Madison
The goal of this program is to reduce the incidence of healthcare-associated infections (HCAIs). After hearing and assimilating this program, the clinician will be better able to:
1. Explain why the risk for HCAIs is higher in intensive care units (ICUs).
2. Discuss possible reasons for failure of hospital to reduce the incidence of HCAIs.
3. Describe how HCAIs are transmitted in the hospital, particularly in the ICU.
4. Adopt evidence-based preventive measures, (eg, hand hygiene), barrier precautions, and chlorhexidine sponge baths).
5. Utilize innovative technologies to prevent HCAIs.
In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the planning committee to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, Dr. Maki and the planning committee reported nothing to disclose.
Dr. Maki was recorded at the 2008 Update on Infectious Diseases, held July 23-25, 2008, in Middleton, WI, and sponsored by the Section of Infectious Diseases, Department of Medicine, University of Wisconsin School of Medicine and Public Health and the Office of Continuing Professional Development in Medicine and Public Health. The Audio-Digest Foundation thanks Dr. Maki and the sponsors for their cooperation in the production of this program.
Profile of Nosocomial Infections
Epidemiology: 5% to 7% of patients admitted to acute-care secondary or tertiary hospitals develop infection; in small community hospitals, risk significantly lower (2%-3%); most infections bacterial; major sites catheter-associated urinary tract infections (UTIs), surgical-site infections, pneumonias, and bacteremias (incidence now almost 1%); Clostridium difficile infection increasing; multiresistant gram-positive organisms more common than gram-negative; health care (HC)-associated infections (HCAIs) synonymous with antibacterial resistance; resistance seen in virtually all pathogens acquired in hospital; risk 3 to 5 times higher in intensive care unit (ICU) than in non-ICU patient-care areas, with almost 10 times higher rates of bacteremia and pneumonia; infection powerful predictor of nonsurvival in ICU; ICUs — breeding ground for antibiotic-resistant organisms; for past 15 yr, Pseudomonas aeruginosa number one pathogen in ICUs in United States; methicillin-resistant Staphylococcus aureus (MRSA) 60% of time; coagulase-negative staphylococci, resistant enterococci (one-third of all enterococcal isolates), and multiresistant enterobacteriaceae common in ICU setting; two-thirds of all HCAIs occur in 10% to 15% of patients in ICU at any given time; workers in ICU more vulnerable to developing occupationally acquired infections
Evolution of infection control: development of hospital infection control programs with formally trained personnel; measures —surveillance of infections; more consistent hand washing; better aseptic technique with invasive devices; compliance with isolation of patients colonized or infected with contagious or especially resistant organisms; universal precautions for preventing bloodborne viral infections in HC workers; aggressive outbreak investigations; cohort nursing in epidemics; education; behavior modification to implement measures
Reasons for failure: patients becoming more vulnerable to infections — nearly one-third of 1 million patients in United States have organ transplants (commonly readmitted to hospitals and have higher vulnerability to infections, particularly HCAI); progressive shortage of ICU nurses — literature shows that by assigning ICU nurses to more patients, risk for infections, particularly bacteremia and pneumonia, increases from 50% to 2- to 3-fold; surveillance almost nonexistent in some hospitals — many hospitals perform only spot surveillance, so unable to grasp extent of problem; resistance rates (legitimate surrogate marker for effectiveness of infection control) rising; rates of C difficile infection in general population approaching 1% of adults >65 yr of age; rapid spread of supertoxigenic strain of C difficile most alarming (associated with high rates of mortality); resources for infection control stretched too thin in many hospitals; favorable factors — majority of nosocomial infections device- or procedure-related (good grasp of pathogenesis and epidemiology of most nosocomial infections, particularly those related to devices and procedures); should be able to apply this information to develop strategies for prevention
Goals in infection control: improve safety of high-risk procedures, eliminating them when possible; protect patients from colonization, since colonized patients major source of cross-infection
Transmission: organisms acquired from environment, contact with medical personnel, or occasionally, by airborne route; contact — major mode of transmission of majority of bacterial pathogens, some viruses, and ectoparasites; growing evidence that MRSA, vancomycin-resistant enterococci (VRE), Acinetobacter, and C difficile common contaminants of environmental surfaces contiguous to patients; possible important source of infection in ICU; air — major source of spread of tuberculosis, filamentous fungi (eg, Aspergillus), severe acute respiratory syndrome (SARS), influenza virus, and exanthem viruses; water — major reservoir of Legionella, and in some settings, reservoir of Pseudomonas; HC worker — can become chronic carrier of S aureus, coagulase-negative staphylococci, and Acinetobacter, and spread disease (relatively rare)
Evidence-based Preventive Measures
Hand contamination: transient carriage of organisms on hands of HC workers still major mode of spread of most pathogens in hospital; study showed that with 15-sec rinse, 60,000 colony-forming units (CFUs) cultured from hands of average nurse or physician; at any point in time, nearly 50% of HC workers have gram-negative rods on hands, and 10% have S aureus; culturing individuals at random thrice weekly showed 100% have gram-negative rods on hands, two-thirds have S aureus, and 5% to 10% of these are MRSA; 3 days later, spectrum of organisms different (depends on contact with colonized patients); speaker’s study — found that with standard 10-sec hand washing with soap and water, more organisms cultured off individual’s hands than before hand washing; using antiseptic reduces infection — studies show that use of good antiseptic (eg, chlorhexidine), even with only 10 sec of exposure, leads to substantial reduction in organisms; study performed 25 yr ago showed that use of antiseptic with conventional hand washing in ICU translated to »30% lower incidence of nosocomial infections
Hand hygiene: encompasses conventional hand washing and use of waterless alcohol gels or hand rubs (shown as effective as hand washing with chlorhexidine and easier on hands due to incorporated emollients); recommended that HC workers use antimicrobial-containing sulfur detergent or alcohol-based hand rub before and after contact with patients or their environment or before performing invasive procedures; if hands become soiled, worker should use conventional hand washing, ideally with soap and water or antiseptic-containing hand washing agent before use of alcohol-based hand rub; conventional hand washing recommended before contact with patient suspected or known to be C difficile-positive (spores not eliminated by alcohol); hand hygiene also recommended before and after donning gloves (not based on substantial data)
Barrier precautions: placing patient in isolation; requires gown and gloves; deployment of isolation precautions inadequate (predicated upon waiting for knowledge that patient positive; by that time, patient handled by several HC workers, and good chance that resistant strain spread to other patients); due to “iceberg phenomenon” (for every known infected patient, probably 3 or 4 patients carrying infection but not known); true with MRSA, VRE, resistant gram-negative rods, and C difficile; protecting patients from MRSA and other resistant organisms in hospital —prospective studies looked at likelihood of infection if individual exposed to resistant organisms in hospital; data show that 1 in 3 manifest clinical infection during hospitalization or in subsequent hospitalization (true for VRE and gram-negative rods); risk not as great outside ICU
Screening: one approach to screen everyone for carriage of resistant organisms when they enter hospital and, if positive, initiate isolation; numerous studies suggest it reduces spread and terminates outbreaks; one study showed substantial reduction in MRSA infections with universal screening; however, screening expensive, with 24- to 72-hr delay in obtaining results; necessary to repeat every 5 to 7 days in long-term patients; addresses only one pathogen
Study data: large prospective randomized controlled trial involving 19 academic ICUs tested hypothesis that screening on admission reduces risk; outcome measure new MRSA or VRE colonization or infection while in ICU or after discharge from ICU; no benefit found; another large study with lower initial risk for infection failed to demonstrate measurable effect of universal screening on nosocomial MRSA infection rates in vulnerable surgical patients
Preemptive isolation: barrier precautions for all high-risk patients; study looked at high-risk children admitted to pediatric ICU; randomized to standard care vs simple protective barrier isolation (ie, gloves and gowns); found substantial reduction in infections, particularly resistant infections (eg, Pseudomonas, staphylococci), 2-fold reduction in fever days, antibiotic use, and mortality; benefit greater the longer child required protection; gloving alone — possibly sufficient; study from Minneapolis Veterans Hospital showed that standard gloving before all contact with patients with C difficile reduced acquisition of nosocomial C difficile by almost 80%; number of studies in burn units show substantial benefit from preemptive isolation or universal barrier precautions
Chlorhexidine sponge bath: not rinsed off; well tolerated, with no adverse effects; markedly reduces transient flora on surface of skin; study — looked at impact on VRE colonization and showed that giving patients daily chlorhexidine sponge bath resulted in 50% lower rates of colonization and environmental contamination; HC workers much less likely to have VRE on hands, compared to those working with control patients given soap-and-water sponge baths; trial — looked at MRSA infection; showed that daily chlorhexidine sponge bath reduced central line bloodstream infection and reduced MRSA bacteremia to almost zero; simple highly cost-effective approach for preventing spread of MRSA in high-risk settings, particularly ICUs
Innovative Technologies and Prevention
Bacteremia: 200 million intravascular devices used annually translates to almost 500,000 device-related bacteremias annually; with short-term devices, patient’s skin source of 80% of bacteremias; with long-term devices, source is luminal contaminants related to manipulation of connector; evidence-based guidelines for prevention of HCAIs — educating users cuts risk by 50%; maximum barrier precautions cut risk by »50% (with central lines); using chlorhexidine instead of povidone iodine cuts risk by »50%; removing device as soon as possible also reduces risk; during 1990s, incidence of central line-associated bacteremia dropped »30% in US ICUs; systems-based approach — involves all hospital stakeholders; shown to reduce infection to almost zero; study in developing countries — shows that implementing simple infection-control measures in hospitals reduced incidence of bloodstream infections by almost 40%, with 50% reduction at £2 yr; also shows substantial reduction in antibiotic-resistant bloodstream infections
Role of technology: Biopatch — disc impregnated with chlorhexidine; maintains high concentration in skin; prevents invasion of insertion site; effective; multicenter trial showed 60% reduction in bacteremia; no adverse effects; inexpensive; left on for 1 wk, with no need for routine site care; highly cost-effective; integrated dressing — gel impregnated with chlorhexidine that flows around catheter insertion site; in study of volunteers, found as effective as Biopatch in reducing colonization on days 7 and 10; outcome measures not studied, therefore, not yet recommended for use in hospital; treating surface of catheter to prevent formation of biofilm — study looking at chlorhexidine and silver sulfadiazine-impregnated catheter showed substantial reduction in bacteremia, with no evidence of selecting for resistance; coating catheter with minocycline or rifampin — available commercially; effective; meta-analysis of studies of anti-infective-coated central catheters show benefit, with largest study showing »60% risk reduction; however, currently used in <5% of central lines; long-term devices for vascular access — 3 million individuals receive Hickman or long-term dialysis catheter or port annually; one option use of luminal lock solution; study shows that vancomycin lock solution clearly reduced bacteremias in neonatal ICU; ethyl alcohol — speaker studied effects of ethanol on mechanical properties of commercial silicone and polyurethane catheters, exposing them to high concentrations of ethanol for £9 wk; found no evidence of negative impact on mechanical properties; trials show that use of 70% ethanol lock substantially reduced incidence of catheter-related bacteremia with long-term devices, and does not appear to increase thrombosis with locking for extended periods; needleless IV connectors — suggested as possible cause of nosocomial bacteremia; one approach to develop contamination-resistant connectors; inner portion of connector lined with micronized nano-silver preparation to prevent contamination; after 12 hr of exposure to £1 million MRSA/mL, connectors remained almost sterile; outcome study needed
Nosocomial pneumonias: primary pathogens Aspergillus and other filamentous fungi; Aspergillus most common organism in ambient air; risk for death 40% to 50% in Aspergillus invasive pneumonia; air filtration — study >20 yr ago in bone marrow transplant unit showed that filtering air in room with HEPA filter reduced contamination rate of air 10-fold, with striking reduction in invasive Aspergillus infections; nosocomial Legionella pneumonia — prevented by use of continuous addition of silver and copper ions to water; no negative effect on health; ventilator-associated pneumonia (VAP) — large proportion caused by organisms that pool in secretions above cuffed endotracheal tube (ETT); organisms also reflux up from stomach; stomach and hypopharynx continuum constitute reservoir; measures that reduce risk include avoiding intubation unless necessary; noninvasive ventilation results in markedly decreased incidence of pneumonia, length of stay in ICU, and hospital mortality; semirecumbent positioning prevents reflux of organisms from stomach into hypopharynx; Spanish study showed markedly reduced incidence of VAP; Dutch study found most patients elevated 10° to 15°; no benefit if patient not elevated to 30°; if patient placed on ventilator, must humidify lower respiratory tract to prevent desiccation; humidifiers and nebulizers generate significant amount of liquid in tubing, causing growth of organisms that enter lungs; studies show that use of heat-moisture exchanger (low liquid generation) associated with lower risk for VAP; oral care with chlorhexidine —reduces burden of organisms in mouth; results in significant reduction in infection (now standard of care); continuous subglottic suctioning promising approach to prevent VAP; ETT —biofilm forms on surfaces, and organisms may drop off into lower respiratory tract; silver-coated ETT may be resistant to colonization and biofilm formation; large multicenter trial showed significant reduction in VAP
Sharps injuries: »1 million HC workers stick themselves with contaminated needles annually; risk of acquiring hepatitis B, hepatitis C, or HIV, 1 in 1000; work-up almost $1000/case; education alone not enough; technologic changes resulted in »70% decline in incidence
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