Lesson 12 - Healthcare Epidemiology

Epidemiology

• Study of health and disease in healthcare settings

  • Study of the occurrence, determinants, and distribution of health and disease within healthcare settings

• Goal

  • Protect patients, healthcare workers, and visitors.

Importance of Microbiology in Healthcare

• Essential for all health-related occupations:

  • Hospitals, clinics, long-term care, hospice, and home care.

• Need for standardized procedures to prevent infectious diseases.

• Carelessness can lead to preventable infections.

Healthcare-Associated Infections (HAIs)

• Infections acquired within healthcare settings

  • Excludes infections present or incubating at hospital admission.

  • Includes those that erupt within 14 days of hospital charges

  • Many come from the patient themselves because their own indigenous microbiota enters a surgical incision or otherwise gain entrance to areas of the body other than those where they normally reside

  • Categories

    • HAI

    • Community-Acquired Infections

    • Iatrogenic Infections

HAI | Healthcare-Associated Infections

A type of HAI that is develop within healthcare settings.

HAI | Community-Acquired Infections

• A type of HAI that is present at admission or incubating.

  • Infections that are acquired outside health care facilities

HAI | Iatrogenic Infections

• A type of HAI that is physician-induced infections (e.g., surgical site infections and UTI that results from urinary catheterization of patients)

  • Results from medical or surgical treatment

HAI’s Modes of Transmission | Contact Transmission

• Direct: Person-to-person transfer

• Indirect: Via contaminated intermediate objects or persons.

HAI’s Modes of Transmission | Droplet Transmission

• Respiratory droplets (>5μm) transmit infection.

  • Transmit infection when they travel from the respiratory tract of an infectious individual to susceptible mucosal surfaces of a recipient

  • E.g., Sneezing or coughing.

HAI’s Modes of Transmission | Airborne Transmission

• Airborne droplet nuclei or small particles (≤5μm).

• Occurs with dissemination of either airborne droplet nuclei or small particles containing pathogens

Most Common Type of HAI | Urinary Tract Infection (UTIs)

• ~32% of all HAIs.

• Cause ~13% of deaths associated with HAIs.

Most Common Type of HAI | Surgical Site Infections (SSIs)

~22% of all HAIs.

Cause ~8% of deaths associated with HAIs.

Most Common Type of HAI | Lower Respiratory Tract Infections

• ~15% of HAIs.

• Cause ~36% of deaths associated with HAIs.

• E.g., pneumonia

Most Common Type of HAI | Bloodstream Infections (Septicemia)

• ~14% of HAIs.

• Cause ~31% of deaths associated with HAIs.

Most Common Type of HAI | Gastrointestinal Infections (C. difficile)

• Caused by antibiotic disruption of gut flora.

  • Anaerobic, spore-forming, Gram-positive bacillus

  • Symptoms: AAD, PMC (Antibiotic-Associated Diarrhea, Pseudomembranous Colitis).

Patients Most Likely to Develop HAIs

• High-Risk Groups

  • Elderly, premature infants, newborns.

  • Women in labor, surgical, and burn patients.

  • Patients with diabetes, cancer, cystic fibrosis.

  • Immunosuppressed individuals (organ transplants, dialysis, etc.; most likely).

• ICU Patients

  • Highest infection rates.

  • HAI rates ~3x higher than general hospital patients.

• Contributing Factors

  • Aging population, increasingly aggressive medical and therapeutic interventions, an increase number of implanted prosthetic devices, organ transplantations, xenotransplantation

Major Factors Contributing to HAIs

• Increasing number of drug-resistant pathogens.

• Non-compliance with infection control guidelines.

• Growing population of immunocompromised patients.

• Contributing Factors

  • Overcrowding, staff shortages, lengthy surgeries.

  • Overuse of antibiotics and indwelling medical devices.

  • Lack of training for healthcare workers.

Reducing the Number of HAIs

• Primary Strategy

  • Strict compliance with infection control guidelines.

    • Key Measures

      • Frequent and proper handwashing:

        • Use soap, warm water, scrub for 10–15 seconds.

        • Dry from forearms to fingertips.

• Proper sterilization and disinfection.

• Isolation of infectious patients.

• Use of personal protective equipment (PPE).

• Handwashing

Infection Control Practice | Medical Asepsis (Clean Technique)

• an infection control practice which reduces pathogen transmission.

  • Goal is to exclude pathogens

  • Includes hand hygiene, cleaning equipment, and disinfection.

  • Includes all the precautionary measures necessary to prevent direct transfer of pathogens from person-to-person and indirect transfer of pathogens

Infection Control Practice | Surgical Asepsis (Sterile Technique)

• an infection control practice which excludes all microbes.

  • Used in invasive procedures (e.g., surgeries, catheterizations).

  • includes practices used to render and keep objects and areas sterile

Joseph Lister (1827-1912)

• Introduced antisepsis using phenol in surgeries.

• Developed sterilization techniques (e.g., steam, sterile gloves).

• Reduced surgical wound infections significantly.

Ignaz Semmelweis

• Introduced handwashing

• “Father of Handwashing”, “Father of Hand Disinfection”, and “Father of Hospital Epidemiology”

Disinfection

Eliminates most pathogenic microbes on inanimate objects.

Category of Disinfectant | Chemical Sterilants

Kill bacterial spores with prolonged exposure (3–12 hours).

Category of Disinfectant | High-Level Disinfectants

Eliminate all microbes except high numbers of spores.

Category of Disinfectant | Intermediate-Level Disinfectant

Kill mycobacteria, bacteria, viruses, and fungi but not bacterial spores.

Category of Disinfectant | Low-Level Disinfectants

• Effective against vegetative bacteria, some fungi, and viruses in ~10 minutes.

• May be used for noncritical items

Spaulding System for Instrument Classification | Critical Items

• High risk of infection if they are contaminated with any microbe; require sterilization

  • Examples: Surgical instruments, cardiac and urinary catheters, and implants.

  • Methods: Steam sterilization, ethylene oxide gas, or chemical sterilants.

Spaulding System for Instrument Classification | Semi-critical Items

• Contact mucous membranes or non-intact skin; need high-level disinfection (glutaraldehyde, hydrogen peroxide, peracetic acid with hydrogen peroxide).

  • Examples: Respiratory therapy and anesthesia equipment, and endoscopes.

Spaulding System for Instrument Classification | Noncritical Items

• Contact intact skin only; low-level disinfection is sufficient.

  • Divided into 2 categories

    • Noncritical Patient-Care Items

    • Noncritical Environmental Surfaces

  • Examples: Bedpans, blood pressure cuffs, bedside tables.

Techniques for Surgical Asepsis

• Preparation

  • Surgical scrubbing of hands and fingernails.

  • Wearing sterile masks, gloves, caps, gowns, and shoe covers.

• Environment

  • Use of sterile solutions, drapes, and fields.

  • Heat-sterilized surgical instruments.

• Goal

  • Prevent the introduction of microbes into sterile fields.

Regulations | OSHA Bloodborne Pathogen Standard (29 CFR 1910.1030)

• requires facilities having employees who have occupational exposure to blood or other potentially infectious materials to prepare and update a written plan

• Exposure Control Plan

• Designed to protect health care personnel

• Topics Covered

  • Postexposure follow-up

  • Recordkeeping for bloodborne pathogens

  • Needlestick injuries and sharps handling

  • Universal precautions and latex allergy

  • Bloodborne illnesses: HIV, HBV, HCV

  • Labeling and signage requirements

Regulations | Standard Precautions

• Combines Universal Precautions and Body Substance Isolation Precautions

  • This applies to all patients in all healthcare settings

  • Its implementation constitutes the primary strategy for the prevention of health care-associated transmission of infectious agents between patients and health care personnel

  • Protects both health care personnel and patients

  • Key Elements

    • Hand hygiene and personal protective equipment (PPE)

  • Safe injection practices

  • Environmental cleaning and disinfection

  • Handling soiled linens and sharps disposal

Regulations | Handhygiene

• Most critical infection prevention method

• Most important and most basic technique in preventing and controlling infections and preventing the transmission of pathogens

  • Guidelines

    • Wash hands before and after patient contact

    • Use antimicrobial agents in specific scenarios

    • Alcohol-based hand rubs for unsoiled hands

    • Avoid artificial nails and rings during patient care

PPE Component | Gloves

• a PPE component use during exposure to blood, body fluids, or contaminated items

  • Can protect both patients and health care personnel from exposure to infectious materials that may be carried on hands

  • must be worn when:

    • anticipating direct contact with blood or body fluids, mucous membranes, non-intact skin, and other potentially infectious materials

    • having direct contact with patients who are colonized or infected with pathogens transmitted by the contact route

    • handling or touching visibly or potentially contaminated patient-care equipment and environmental surfaces

PPE Component | Gowns

• Worn to protect skin and clothing

• Protect the health care worker’s arms and exposed body areas and prevent contamination of clothing with blood, body fluids, and other potentially infectious material

  • Standard Precaution

    • Worn if contact with blood or body fluid is anticipated

  • Contact Precautions

    • Used, donning of both gown and gloves upon room entry is indicated

PPE Component | Masks

• For protection against infectious droplets or during sterile procedures

• Removed after gloves are removed

PPE Component | Eye Protection

• Goggles or face shields for splash prevention

  • Removed after gloves are removed

PPE Component | Respiratory Protection

a PPE component that refers to the use of N95 respirators for airborne pathogens

Regulations | Environmental Control

• Routine cleaning and disinfection of surfaces

• Proper handling of soiled linens and patient-care equipment

• Sharps Disposal

  • Use rigid, puncture-resistant containers

  • Avoid recapping or bending needles

  • Placed in sharp containers

Regulations | Transmission-Based Precautions

• Used for patients who are known or suspected to be infected or colonized with highly transmissible or epidemiologically important pathogens for which additional safety precautions beyond Standard Precautions are required to interrupt transmission within hospitals

  • Used in addition to Standard Precautions

  • Enforced only for certain specific types of infections

Type of Transmission-Based Precautions | Contact Precautions

• Used for patients known or suspected to be infected or colonized with epidemiologically important pathogens that can be transmitted by direct or indirect contact

  • For multidrug-resistant organisms, C. difficile, etc.

Type of Transmission-Based Precautions | Contact Enteric Precautions

Used whenever a patient has C. difficile or Norovirus infection and signifies that the HCW needs to use soap and water for hand hygiene rather than alcohol-based product

Type of Transmission-Based Precautions | Droplet Precautions

• For patients known or suspected to be infected with microbes transmitted by droplets that can be generated in the ways previously mentioned

  • For respiratory droplets >5 µm (e.g., influenza)

Type of Transmission-Based Precautions | Airborne Precautions

• Applied to patients known or suspected to be infected with epidemiologically important pathogens that can be transmitted by the airborne route, such as TB or measles

  • For droplet nuclei ≤5 µm (e.g., tuberculosis)

Specialized Patient Environment | Airborne Infection Isolation Rooms (AIIR)

• Negative pressure (to prevent room air from entering the corridor when the door is opened) and HEPA filtration for airborne pathogens (to be removed when leaving)

  • Preferred placement for patients who are infected with pathogen that are spread via airborne droplet nuclei, and therefore require Airborne Precautions

Specialized Patient Environment | Protective Environments

• A well-sealed single-patient room in which vented air entering the room is passed through HEPA

  • Positive pressure rooms (to prevent corridor air from entering when door is opened) for immunocompromised patients

  • “protective isolation”, “positive pressure isolation”

Regulations | Vaccinations for Healthcare Personnel

• Hepatitis B

• Influenza (annually)

• Measles, Mumps, Rubella

• Varicella-Zoster (chickenpox)

• Tetanus-diphtheria-pertussis

• Meningococcal vaccine (for microbiologists who are routinely exposed to isolates of Neisseria meningitidis)

Regulations | Handling Food and Eating Utensils

• Safe Practices

  • Proper storage, preparation, and disposal of food

  • Hand hygiene before food handling

  • Routine health checks for food handlers

• The combination of hot water and detergents used in dishwashers is sufficient to decontaminate dishware and eating utensils

  • No special precautions are needed

Urinary Catheters

Provide a “superhighway” for indigenous microbiota of the distal urethra to gain access to the urinary bladder

Infection Prevention and Control

• Pertains to the numerous measures that are taken to prevent infections from occurring within health care settings

  • Include actions taken to eliminate or contain reservoirs of infection, interrupt the transmission of pathogens, and protect person from becoming infected

Sharp Containers

• Rigid, puncture resistant, leak proof, disposable, and clearly marked with a biohazard label

  • Must be easily accessible to all personnel needing them

Single Rooms

Always indicated for patients placed on Airborne Precautions and are preferred for patients requiring Contact or Droplet Transmission

Earle H. Spaulding

He devised a system of classifying instruments and items for patient care according to the degree of risk for infection that was involved

N95 Respirators

• They are tight-fitting, adjustable masks that are designed to protect against small droplets of respiratory fluids and other air-borne particles in addition to all the protection afforded by surgical mask

  • Filters at least 95% of airborne particles

Focus of Epidemiology

Infection control and preventing healthcare-associated infections (HAIs).

Scope of Epidemiology

• Surveillance measures.

• Risk reduction programs.

• Policy development and implementation.

• Education on infection control.

• Cost–benefit assessment of prevention programs.

• Elimination of infection reservoirs and transmission pathways.

Perfusionist

A skilled professional who operates extracorporeal circulation equipment during any medical situation in which it is necessary to support or temporarily replace the patient’s circulatory or respiratory function

Fomites

• refers to any nonliving or inanimate objects other than food that may harbor and transmit microbes

• e.g., patients’ gowns, bedding, towels, and eating and drinking utensils, and hospital equipments

Biohazards

refers to the materials or substances that are harmful to heatlh

Challenges in Infection Control

• Nurses’ Practices in a Tertiary Hospital in Baguio City

  • Good knowledge but suboptimal infection prevention practices.

• Key barriers:

  • Heavy workloads due to staff shortages.

  • Inadequate dissemination of updated guidelines.

  • Discomfort with personal protective equipment (PPE).

Predominant Pathogens | Positive Cocci

• Staphylococcus aureus (including MRSA).

• Coagulase-negative Staphylococci.

• Enterococcus spp. (including VRE).

Predominant Pathogens | Gram-Negative Bacilli

• Escherichia coli

• Pseudomonas aeruginosa

• Enterobacter spp.

• Klebsiella spp.

Drug Sensitivity | Pseudomonas species

Ceftazidime.

Drug Sensitivity | Klebsiella

Meropenem