Healthcare-associated infections (HAIs) can be defined as, (i) the infections acquired in hospital by a patient admitted for a reason other than the infection in context, (ii) the infection should not be present or incubating at the time of admission, and (iii) the symptoms should appear at least after 48 hours of admission. This also include:
- Infections acquired in the hospital but symptoms appearing after discharge.
- Occupational infections among staff of the healthcare facility (e.g. needle stick injury transmitted infections).
- Infection in a neonate that results while passage through the birth canal (in contrast to congenital infections due to transplacental transmission, which are not HAIs).
As the healthcare delivery system has increasingly shifted from inpatient hospital care based service to the ambulatory setting, the relevance of traditional terminologies such as “hospital-associated or nosocomial” infections has diminished.
Centre for Disease Control and Prevention (CDC), Atlanta recommends to use “Healthcare-associated infections” as a more accepted terminology, because it represents all type of healthcare delivery systems such as hospitals, nursing homes, rehabilitation facility, outpatient clinics, day care and other clinical settings.
Healthcare-associated infections (HAIs) are one of the most common adverse events in the care delivery system. Both the endemic burden and the occurrence of epidemics of HAI are a major public health problem, posing a significant impact on morbidity, mortality, quality of life and also present an economic burden at the societal level. In 2011, World Health Organization (WHO) reported that:
- On average at any given time 7% of patients in developed and 10% in developing countries acquire at least one HAI.
- Mortality from HAI occurs in about 10% of affected patients.
- In Europe, more than 4 million patients are affected by approximately 4.5 million episodes of HAI annually, leading to 16 million extra days of hospital stay and 37,000 attributable deaths; contributing to an annual financial burden of approximately €7 billion.
- In United States of America (USA), it was estimated that around 1.7 million patients are affected by HAI each year, representing a prevalence of 4.5% and accounting for 99,000 deaths with an annual economic impact of approximately US $ 6.5 billion.
Low and Middle-income Countries (LMIC)
Limited data are available from LMICs, but the prevalence of HAI is estimated to be between 5.7% and 19.1%.
- The increased burden of HAI in LMICs affects especially high-risk populations, such as patients admitted to intensive care units (ICUs) and neonates.
- The HAI frequency is several-fold higher in LMIC than in high-income countries, notably for device-associated infections.
- For example, the proportion of patients with an ICU-acquired infection can be as high as one in three in LMICs.
- Increased length of hospital stay associated with HAI in developing countries ranges between 5 days and 29.5 days and excess mortality due to these infections in adult patients in Latin America, Asia and Africa were 18.5%, 23.6% and 29.3% for catheter-associated urinary tract infections, central line associated bloodstream infections and ventilator-associated pneumonia, respectively.
HAIs pose a significant (and largely avoidable) economic impact both at the patient and healthcare facility level. This includes both direct hospital costs, indirect and intangible costs to both patient and healthcare services.
- Direct cost to health services due to the increased length of hospital stay and the overall impact on the facility, as well as unnecessary investigations, procedures and treatment.
- Indirect costs to patients & caregivers due to:
- Loss of job or paid working days or diminished worker productivity on the job.
- Income lost by family members.
- Intangible cost due to:
- Psychological costs, (i.e. anxiety, grief, disability, job loss).
- Pain and suffering.
- Foregone leisure time.
- Time spent by family or friends for hospital visits, travel costs, home care.
- Change in social functioning or daily activities.
EPIDEMIOLOGICAL CHAIN OF HAI2
Traditional epidemiologic triad model shows that infectious diseases result from the interaction of agent, host, and environment. More specifically, transmission occurs when the agent leaves its reservoir or host through a portal of exit, is conveyed by some mode of transmission, and enters through an appropriate portal of entry to infect a susceptible host (Table 1.1 and Fig. 1.1).
At this context, an understanding of source of infection, mode of transmission and etiological agents causing HAI is essential.
Host susceptibility plays an important role in acquiring HAIs.
- Immunity: Majority of the hospitalized patients has impaired immunity either as a part of their preexisting disease processes or, in some instances, due to the treatment they have received in the hospital.Impaired immunity poses the patients to increased risk of acquiring HAI. Healthcare workers (HCWs) exposed to the same hospital environment are at lesser risk of acquiring HAI because of their stronger immunity.
- Age: Neonates and elderly patients are more susceptible than adults.
- Underlying comorbidities such as diabetes, increases the risk of acquiring HAIs.
- Patient undergoing diagnostic or therapeutic interventions: Patients on devices such as intravenous (IV) or urinary catheters, or endotracheal tube are at increased risk of acquiring infection.
- Patient receiving transfusion: Blood, blood products and IV fluids used for transfusion, if not properly screened, can transmit many blood borne infections (BBI) such as HIV, hepatitis B and C viral infections.
Sources of Infection
The source of HAI may be either endogenous or exogenous.
- The majority of nosocomial infections are endogenous in origin, i.e. they involve patient's own microbial flora which may invade the patient's body during some surgical or instrumental manipulations.
- For endogenous infections, the patient admitted to the facility was either priorly colonized with these microorganisms or became colonized at some point during the stay at the facility after admission.
- It may not be possible to determine whether an organism isolated from a patient with a HAI is exogenous or endogenous in origin and in such situations, the term autogenous should be used.
- Autogenous infection indicates that the infection was derived from the flora of the patient, whether or not the infecting organism became part of the patient's flora subsequent to admission.
Exogenous sources are from hospital environment, staff, or patients.
- Environmental source: The hospital environment harbors a greater magnitude of microorganisms than that of community.
- Transmission of these organisms to the patients can cause nosocomial outbreaks of infection.
- The various environmental sources include inanimate objects, air, water and food in the hospital. Inanimate objects in the hospital are medical equipment (endoscopes, catheters, etc.) bed pans, surfaces contaminated by patients’ secretions, excretions, blood and body fluids.
- Healthcare workers may be potential carriers, harboring many organisms; which may be multidrug resistant, e.g. nasal carriers of methicillin-resistant Staphylococcus aureus (MRSA).
Most of HAI causing pathogens are multi-drug resistant. This is due to the increased antibiotic usage in the hospital environment, which leads to the minor population of resistant organisms present initially to flourish under the influence of contact and selective antibiotic pressure. These drug resistant bugs slowly replace the susceptible strains.
The vast majority of HAI are caused by ESKAPE pathogens. This is an acronym proposed by the Infectious Disease Society of America (IDSA), which represent a list of pathogens that are capable of “escaping” the biocidal action of antibiotics and mutually representing new paradigms in pathogenesis, transmission and resistance:
- Enterococcus faecium
- Staphylococcus aureus
- Klebsiella pneumoniae
- Acinetobacter baumannii
- Pseudomonas aeruginosa
- Enterobacter species
This list has been expanded to “ESKAPES” to include Stenotrophomonas maltophilia. Although not enlisted by IDSA, Escherichia coli is also an important agent of multidrug-resistant organism (MDRO) causing HAI especially in Indian settings.
Other less common infections that can be transmitted in hospitals include:
- Healthcare associated M. tuberculosis
- Legionella pneumophila
- Candida albicans
- Clostridioides difficile diarrhea
- Blood borne viruses (BBVs) such as HIV, hepatitis B and C viruses transmitted through contaminated needle prick injury or mucocutaneous exposure to blood and body fluids.
Mode of Transmission
Microorganisms spread in the hospital through several modes (Table 1.2).
Though several types of HAIs exist, there are four most common types (listed below) which are often monitored to estimate the burden of HAI in a hospital. Out of these, the first three together are termed as device associated infections (DAIs):
- Catheter-associated urinary tract infection (CAUTI)
- Central line-associated blood stream infection (CLABSI)
- Ventilator-associated pneumonia (VAP)
- Surgical site infection (SSI).
The pathogenesis, laboratory diagnosis, treatment and prevention of these major HAI types have been described in detail in Chapter 3 and the surveillance aspects has been described in Chapter 4.
The preventive measures for HAIs can be broadly categorized into:
- Standard precautions
- Transmission-based or specific precautions.
Standard (Routine) Precautions
It refers to a set of infection control practices used to prevent transmission of diseases, that can be acquired by contact with blood, body fluids, non-intact skin (including rashes), and mucous membrane.
- These measures should be followed when providing care to all individuals, while handling all specimens and sharps regardless of their infectious status.
- Components of standard precautions include hand hygiene, personal protective equipment, handling of sharps, biomedical waste management, environmental disinfection practices, etc. which have been described in detail subsequently in further chapters.
Transmission-based or Specific Precautions
These are the additional precautions taken over and above the standard precautions when a disease of a specific transmission is suspected and when standard precautions may not be sufficient enough to prevent the transmission of infection.
Based on the specific modes of transmission as discussed earlier in Table 1.2; there are three types of transmission-based precautions:
- Contact precautions
- Droplet precautions
- Airborne precautions.
The detail discussion of transmission based precautions has been described in Chapter 7.
WHO'S PROPOSED CORE COMPONENTS FOR INFECTION PREVENTION AND CONTROL1
The WHO has recently published the “core components for infection prevention and control (IPC)” in 2016. It has recommended eight evidence-based core components which need to be implemented both at healthcare facility level and at national level. All the core components are equally important and crucial for the establishment and effective functioning of IPC practices.
- Infection prevention and control program with a dedicated, trained team should be in place for the purpose of preventing HAI and combating antimicrobial resistance (AMR).
- Infection prevention and control guidelines: Evidence-based IPC guidelines should be developed and implemented for the purpose of reducing HAI and AMR.
- Surveillance: Facility-based HAI surveillance should be performed to guide IPC interventions and detect outbreaks, including AMR surveillance with timely feedback of results to HCWs, stakeholders and to national networks. National HAI surveillance program and networks should be established for the purpose of creating a national benchmark of HAI rates which can be used as standard for inter-hospital comparison.
- Multimodal strategies: IPC activities using multimodal strategies should be implemented to improve practices and reduce HAI and AMR. The 5 most common components of WHO's multimodal strategies include:
- System change (that is, availability of the appropriate infrastructure and supplies to enable good IPC practices).
- Education and training of HCWs and key players.
- Monitoring infrastructures, practices, processes, outcomes and providing data feedback.
- Reminders in the workplace or visual communication posters.
- Cultural change with the establishment and strengthening of a safety climate.
- Monitoring or audit of IPC practices and feedback: Regular monitoring or audit of healthcare practices according to IPC standards should be performed to prevent and control HAI and AMR at the healthcare facility level. Feedback should be provided to all audited persons and relevant staff.
- A national IPC monitoring and evaluation program should be established to assess the extent to which standards are being met and activities are being performed.
- Hand hygiene monitoring with feedback should be considered as a key performance indicator at the national level.
- Workload, staffing and bed occupancy: Bed occupancy should not exceed the standard capacity of the facility; HCWs staffing levels should be adequately assigned according to patient workload.
- Built environment, materials and equipment for IPC at the facility level: Patient care activities should be undertaken in a clean and/or hygienic environment that facilitates practices related to the prevention and control of HAI, as well as AMR. Materials and equipment to perform appropriate hand hygiene should be readily available at the point of care.
For the purpose of increase in awareness, there are several infection control events which are observed worldwide.
- World Hand Hygiene Day: 5th May is observed every year as world hand hygiene day.
- WHO theme on hand hygiene: The WHO theme on hand hygiene in last three years were:
- 2018: It's in your hands—“prevent sepsis in healthcare”
- 2017: Fight antibiotic resistance—It's in your hands.
- 2016: See your hands—hand hygiene supports safe surgical care.
- Global Handwashing Day: 15th October is observed as Global Handwashing Day. It is a campaign to motivate and mobilize people around the world to improve their handwashing habits.
- International Infection Prevention Week: 3rd week in October is designated as International Infection Prevention Week. For 2018, it was observed during 14th to 20th October with a theme of “protecting patients everywhere.”
- World Antibiotic Awareness Week: World Antibiotic Awareness Week aims to increase awareness of global antibiotic resistance and to encourage best practices among the general public, healthcare workers and policy makers to avoid further emergence of antimicrobial resistance. 2nd or 3rd week of November is celebrated every year as antibiotic awareness week. The theme used in last three years were:
- In 2018, it was observed during 12th to 18th November with a theme of “Learn on how to handle antibiotics with care.”
- In 2017, it was observed during 13th to 19th November with a theme of “Think twice, seek advice.”
- In 2016, it was observed during 14th to 20th November with a theme of “Antibiotics: handle with care.”
PIONEERS IN INFECTION PREVENTION AND CONTROL
Since time immemorial, many scientists, medical and surgical physicians have contributed largely to infection control and prevention. The historical context of hospital infection control has been briefly summarized in Table 1.3.
- World Health Organization. Guidelines on core components of infection prevention and control program at the national and acute healthcare facility level. World Health Organization; 2016.
- Scott RD. (2009). The direct medical costs of healthcare-associated infections in US hospitals and the benefits of prevention. [online] Available from https://www.cdc.gov/hai/pdfs/hai/scott_costpaper.pdf/. [Accessed October 2018].
- Ling ML, Apisarnthanarak A, Madriaga G. The burden of healthcare-associated infections in Southeast Asia: a systematic literature review and meta-analysis. Clin Infect Dis. 2015;60(11):1690–9.
- Horan TC, Andrus M, Dudeck MA. CDC/NHSN surveillance definition of healthcare-associated infection and criteria for specific types of infections in the acute care setting. Am J Infect Control. 2008;36(5):309–32.
- World Health Organization. (2018). Save Lives: Clean Your Hands 5 May 2018. [online] Available from http://www.who.int/infection-prevention/campaigns/clean-hands/5may2018/en//. [Accessed October 2018].
- Global Handwashing Day. (2018). October 15 is Global Handwashing Day. [online] Available from https://globalhandwashing.org/global-handwashing-day//. [Accessed October 2018].
- Infection Prevention and You. (2018). Member Toolkit. [online] Available from http://professionals.site.apic.org/iipw/promotional-toolkit//. [Accessed October 2018].
- World Health Organization. (2018). World Antibiotic Awareness Week, 12–18 November 2018. [online] Available from http://www.who.int/campaigns/world-antibiotic-awareness-week/en//. [Accessed October 2018].
- Sunavala A, Singhal T, Soman R. Pioneers in Infection Prevention-Part 1. J Assoc Physicians India. 2015;63(11):71–2.
- Sunavala A, Singhal T, Soman R. Pioneers in Infection Prevention-Part 2. J Assoc Physicians India. 2015;63(12):90–1.
- Smith PW, Watkins K, Hewlett A. Infection control through the ages. Am J Infect Control. 2012;40(1):35–42.