Healthcare Associated Infections (HAIs)
Introduction to Human Disease
IDH.7 Disease Transmission: Introduction to Community and Healthcare-Associated Infections (HAIs)
Learning Outcomes
Discuss types of healthcare-associated infections (HAIs) and their prevalence, specifically focusing on:
Methicillin-Resistant Staphylococcus Aureus (MRSA)
Vancomycin-Resistant Enterococcus (VRE)
Clostridioides difficile (C. diff)
Explain mechanisms of transmission for these infections within healthcare environments.
Describe best practices to combat the spread of infections, encompassing:
Healthcare professional practices
Hospital maintenance and cleanliness
Effective hygiene practices
Infrastructure improvements for infection control
What are Healthcare-Associated Infections (HAIs)?
Definition: HAIs are infections that patients acquire while receiving treatment for medical or surgical conditions within a healthcare setting. These infections can manifest in various environments, including:
Post-Treatment Settings: Such as outpatient clinics and nursing homes.
Prevalent Types of HAIs include:
Respiratory Tract Infections: Often include pneumonia, among others.
Urinary Tract Infections: A common complication, particularly post-catheterization.
Bloodstream Infections (BSI): Serious and often lifethreatening conditions resulting from invasive procedures.
Gastrointestinal Infections: Frequently associated with antibiotic use disrupting normal flora.
Historical Context of HAIs
Ignaz Semmelweis: often referred to as the 'father of infection control.'
Semmelweis's significant contributions arose from his observations regarding maternal mortality rates in obstetric wards, highlighting the role of healthcare professionals in the transmission of infections.
He noticed how there were higher mortality rates associated with obstatricians who did not wash their hands compared to midwives who maintained better hygiene practices, leading him to advocate for handwashing as a simple yet vital method to reduce infections.
Importance of Healthcare-Associated Infections (HAIs)
Increased Mortality (Death Rate): ~ 25% of patients with Staphylococcus aureus blood stream infection (BSI) may die due to infection.
Increased Morbidity (Being Diseased/Unhealthy): Patients suffering from post-surgical wound infections tend to stay in the hospital longer.
Healthcare Costs:
Hospital treatment or medications (e.x., antibiotics/ x-rays)
Patients (e.x., loss of income while recovering)
Society (e.x., disability payments/ tax)
Increased Awareness: Growing public and governmental awareness regarding HAIs
Antimicrobial resistance
Origins of HAIs
Sources of HAIs are diverse, stemming primarily from:
Exogenous - pathogens originating from external sources, such as:
Other Patients
Staff
Surrounding Environment or Equipment
This way of contamination is completely preventable through proper sanitation protocols and staff training on hygiene practices!!
Endogenous - pathogens originating from the patients own flora
This way of contamination is difficult to prevent!
How are Pathogens Transmitted?
Transmission Routes:
Person-to-Person Contact: Involves direct or indirect contact (e.x., skin carriage).
Respiratory Transmission: Pathogens spread through aerosolised droplets generated by coughing and sneezing.
Faecal-Oral Route: Often linked to gastrointestinal pathogens, transmitted via contaminated hands or surfaces.
Sexual Transmission: Through genital discharges or lesions.
Vertical Transmission: Infection can occur from mother to child during pregnancy (antenatal) or delivery (perinatally).
Factors Contributing to HAIs
Several factors influence the incidence of HAIs:
Microbial Growth and Adaptation:
Bacteria developing resistance to antibiotics.
Biofilm production by bacteria can significantly enhance their survival in hospital environments, making it more challenging to eradicate infections.
Spore production can also play a crucial role in bacterial survival, allowing species to endure harsh conditions and ensure their propagation even in the presence of antimicrobial treatments.
Host Vulnerability:
Immunosuppression increase infection risk
Underlying diseases/ wounds cause an increased susceptibility to infections, as the immune system is compromised, reducing the body's ability to fight off bacterial pathogens effectively.
Extremes of age, such as very young children and elderly adults, can also lead to higher infection rates due to a less robust immune response.
Devices such as IV lines, urinary catheters, or ventilators create potential entry points for pathogens
Environmental Conditions:
Equipment and infrastructure can harbour bacteria
Other humans like staff or other patients
Epidemiological Data
European Data on HAIs – ECDC PPS 2023
Over 4 million HAIs are are estimated to occur annually across European hospitals
At least 20% of these are deemed preventable.
Irish Data on HAIs – PPS 2023
The prevalence rate of HAIs recorded stands at 7.4% in hospitals, with 33.1% of HAIs already present upon patient admission.
Top Three HAIs:
Pneumonia
Urinary Tract Infection
Surgical Site Infection
Top Five Pathogens Associated with HAIs:
E. coli: Frequently implicated in UTIs.
S. aureus: With 23.4% cases being MRSA.
SARS-CoV-2: Impacted healthcare settings significantly during the pandemic.
Clostridioides difficile: Particularly after antibiotic treatments.
E. faecium
Prevention of HAIs
Standard Precautions: Key in preventing the transmission of pathogens.
Hand hygiene
Respiratory Hygiene: Covering coughs/sneezes properly to prevent droplet spread.
Safe Injection Practices: Avoiding reuse of syringes and ensuring sterile equipment.
Transmission-based Precautions:
Safe patient placement
Use of Personal Protective Equipment (PPE): Essential for protecting healthcare workers and preventing cross-contamination.
Cleaning and disinfecting patient care areas and equipment regularly is crucial to maintaining a safe environment.
Decontamination Strategies:
Disposal of waste
Sharps Disposal: Safe and proper disposal to prevent needlestick injuries.
Management of bodily fluid spills
WHOs 5 Moments of Hand Hygeine
Designated critical times to maintain hand hygiene in healthcare settings, which include:
Before patient contact.
Before aseptic procedures.
After body fluid exposure risk.
After patient contact.
After contact with patient surroundings.
Understanding Organisms on Hands
Transient Organisms: Organisms that are easily acquired during patient care, and can be transmitted easily.
Resident Organisms: Naturally occurring skin flora that are typically more difficult to transfer but can still pose infection risks under certain conditions.
Transmission-Based Precautions
Additional precautions necessary when standard precautions are inadequate to prevent transmission of specific infectious agents.
Types include:
Contact Precautions: Used for infections spread through direct contact.
Droplet Precautions: For pathogens transmitted via respiratory droplet route.
Airborne Precautions: Required for infections carried through persistent airborne particles.
Safe Patient Placement
Aim: To reduce the dissemination of microorganisms, and to protect the immunosuppressed patients.
Techniques include isolating high-risk patients and cohorting patients with similar infectious agents to mitigate cross-infection.
Isolation of High-Risk Patients: This involves placing patients who are particularly vulnerable to infections—such as immunocompromised individuals, those with open wounds, or patients undergoing certain treatments—in separate areas. Isolation minimizes their exposure to potential pathogens from other patients and reduces the likelihood of transmission.
Cohorting Patients: This technique groups together patients who are infected or colonised with the same infectious agent. By cohorting, healthcare facilities can limit the movement of healthcare staff and visitors between these groups, thereby minimising the risk of spreading infections. Cohorting is especially effective in controlling outbreaks, as it allows for more focused management, monitoring, and care of affected patients, while also utilising designated resources and staff effectively. These strategies are crucial in infection control practices as they not only protect high-risk patients but also contribute to the overall safety and efficiency of healthcare environments, preventing cross-infection and enhancing patient outcomes.
Decontamination Methods
Cleaning: Involves the removal of visible dirt and contaminants using water and a suitable detergent.
Disinfection: Aims to significantly reduce the number of viable pathogens.
Moist heat
Chemicals
Sterilization: Complete eradication of all microbial life, excluding prions, including bacterial spores.
Heat
Radiation
Chemicals
Examples of Organisms Associated with HAIs
Staphylococcus aureus
Staphylococcus aureus (staph) is a bacterium commonly found on the skin and in the nose of about 30% of individuals. Most of the time staph does not cause any harm, but it can sometimes cause infections. In healthcare settings, infections can lead to serious or fatal outcomes.
Key Characteristics of Staphylococcus aureus:
Habitat: Commonly found in moist skin folds, mucosal surfaces, and the nasopharynx.
Colonization: A significant portion of the healthy human population (20-40%) carries Staph aureus without showing any signs of infection. This is called colonization.
Increased Colonization Risk: Certain conditions increase the likelihood of being colonized…
Diabetes mellitus: Individuals with diabetes may have compromised immune systems and skin integrity.
Injecting drug use: This can introduce the bacteria directly into the bloodstream or create skin breaches.
Presence of foreign bodies/implants: These provide surfaces for bacteria to adhere and form biofilms, making them harder to eradicate.
Infection Potential: Staph aureus can cause infection if there is a break in the skin, such as a cut or wound.
Types of Infections: These infections can range from minor skin issues like boils and pimples to serious and potentially life-threatening infections of the heart (endocarditis), bones (osteomyelitis), and bloodstream (bacteremia/sepsis).
Antibiotic Susceptibility: Generally, Staph aureus strains are susceptible to penicillin-based antibiotics. However, it's important to note that antibiotic resistance, particularly to penicillin and related drugs (like methicillin, leading to MRSA - Methicillin-resistant Staphylococcus aureus), is a significant and growing concern. This information doesn't explicitly mention MRSA, so it likely refers to general, susceptible strains.
Transmission: The primary mode of spread is person-to-person contact, especially via healthcare workers whose hands are not properly washed or cleansed between patient interactions. It can also be acquired from contaminated surfaces.
Methicillin-resistant Staphylococcus aureus (MRSA)
Overview: MRSA is a strain of Staphylococcus aureus that has developed resistance to methicillin and other beta-lactam antibiotics, making it a significant cause of healthcare-associated infections.
Resistance Mechanisms: The resistance of MRSA arises from the acquisition of the mecA gene, which encodes a specific penicillin-binding protein (PBP2a) that does not bind methicillin or other beta-lactam antibiotics.
Prevalence: MRSA is commonly found in hospitals, nursing homes, and other healthcare settings.
Types of MRSA Infections:
Skin and soft tissue Infections
Bloodstream Infections
Bone and Joint Infections
Endocarditis (Infection of the heart valves)
Transmission Risk Factors:
Healthcare-Associated:
Invasive devices (drips, drains)
Open wounds
Weakened immune system
Hospitalization/long-term care
Recent antibiotic use
Surgery
Community-Associated:
Previous MRSA history
Chronic conditions (diabetes, cancer, vascular disease, lung disease)
Intravenous drug use (IVDU)
Close contact with MRSA
Contact sports
Poor hygiene
Community Aquired MSRA: A type of anti-biotic resistant Staphylococcus Aureus that affects healthy individuals in the community.
→ Common Infections in skin and soft tissue and present as boils, abscesses, and cellulitis. It can also lead to necrotising pneumonia in severe cases.
→ Patient Demographics are often young and relatively healthy (ex. athletes, daycare children, prisoners, military, injection drug users…)
→ Antibiotic Resistance is low, but Virulence is high
→ Common in the U.S.
Management and Treatment: Due to its antibiotic resistance, treatment of MRSA infections often requires the use of alternative antibiotics such as vancomycin or linezolid. Infection control measures, including:
Hand Hygiene: Regular and thorough handwashing is crucial to prevent MRSA transmission.
Antimicrobial Stewardship: Prescribing them wisely and correctly.
Isolation: of colonised patients with contact precautions
Topical Decolonisation: of colonised individuals
Vancomycin-resistant Enterococci (VRE)
Enterococci are bacteria that are found in healthy human intestines. While it tends to be harmless in that environment, it has the potential to cause a serious infection if it spreads to other areas of the body.
Natural Antibiotics Resistance: Enterococci have an inherent characteristic of being resistant to multiple different kinds of antibiotics
Vancomycin - Resistant Enterococci (VRE) have developed mechanisms to survive exposure to vancomycin, making infections caused by these bacteria particularly difficult to treat.
Mostly seen in healthcare settings
Can cause:
Urinary tract infections
Intra-abdominal infections
wounds
DOESN’T cause DIARRHOEA
Clostridioides difficile (C. diff)
Definition: Clostridioides difficile (formerly Clostridium difficile) is a gram-positive, anaerobic, spore-forming bacterium and a leading cause of antibiotic-associated diarrhea, particularly in healthcare settings.
Found In: It is a bacteria that can be in the gut in small amounts, but it is also found in the soil, air, water, and faeces.
Mechanism: Antibiotic use disrupts normal gut flora, allowing C. diff spores to germinate, proliferate, and produce toxins that damage the intestinal lining. This leads to a range of symptoms from diarrhea to severe colitis.
Spores:
Survive long periods in harsh environments
Resistant to many disinfectants and requires special cleaning protocols to eradicate from contaminated surfaces.
Resistant to alcohol