Infection Control and Microbiology

Infection Control

• Infection control is important in hospitals and clinics to prevent the spread of infection among patients and staff.
• Objectives include describing sources of microorganisms, transmission routes, and infection control principles; listing universal precautions; understanding risk assessment and management; and explaining vaccines.
• The pre-scientific era saw epidemics and plagues throughout history, with physicians fearing contagious diseases. Climate and environment were blamed for illness, not the ill themselves.

Microbiology – Scientific Era

• Anton van Leeuwenhoek (1632-1722), a Dutch linen draper and amateur scientist, first observed bacteria.
• Ignaz Semmelweis (1818-1865) linked high maternal mortality to doctors not washing their hands after post-mortems, reducing mortality by 90%.

Scientific Era Continued

• Louis Pasteur (1822-1895) showed heat destroys bacteria and fungi, disproving the theory of abiogenesis. He proved bacteria cause infection – the germ theory of disease.
• Joseph Lister (1827-1912) recognized Pasteur's work, was concerned about infections in fractures and post-operative wounds, and developed carbolic acid to disinfect instruments, patients and surgeons.
• Robert Koch (1843-1910) grew bacteria in culture media, showing which bacteria cause specific diseases, and classified most bacteria by 1900.

How Infections Occur

• The chain of infection comprises the infectious agent, reservoir, means of exit, mode of transmission, means of entry, and susceptible host.
• Infections are prevented by controlling the source, managing modes of transmission, and strengthening host defenses.

Breaking the Chain of Infection

• Source control involves coughing etiquette, cleaning, and disinfection.
• Modes of transmission include contact (hand hygiene), droplet (distance), airborne (ventilation), and vector (bednets).
• Portals of entry are managed by adding barriers like PPE.
• Host defenses are strengthened through vaccination.

What the Expert Once Said

• Florence Nightingale emphasized that hospitals should do the sick no harm.

Why Do We Need Infection Control?

• Hospitals and clinics are complex environments where patients receive treatment, yet medical/surgical interventions can introduce health risks.

Nosocomial Infection

• Nosocomial infections are hospital-acquired infections, not present or incubating in the patient when they enter the hospital.
• Consequences include additional morbidity, prolonged hospitalization, long-term physical/neurological sequelae, increased cost of hospitalization, and death.

HAI - Common Bacteria and Viruses

• Common bacteria associated with HAIs include Staphylococci, E. coli, Salmonella, Pseudomonas, Streptococci, and Proteus.
• Common viruses associated with HAIs include Hepatitis A, Hepatitis B, HIV, and Rotavirus.

Responsibilities of the Infection Control Program

• Infection control programs include surveillance of nosocomial infections, outbreak investigations, developing policies for patient isolation and policies to mitigate patient care risks, cooperation with occupational health, education of hospital staff on infection control, ongoing review of infection control techniques, and eliminating wasteful or unnecessary practices.

Universal Infection Control Precautions

• Universal precautions were devised in the US in the 1980s to combat HIV and Hepatitis B.
• Universal precautions treat all patients as potential biohazards and adopt universal routine safe infection control practices to protect patients, staff, and colleagues from infection.

Components of Universal Precautions

• Components of universal precautions include hand washing, personal protective equipment (PPE), preventing/managing sharps injuries, aseptic techniques, isolation, staff health, linen handling and disposal, waste disposal, spillage of body fluids, environmental cleaning, and risk management/assessment.

Hand Washing

• Proper handwashing is the single most effective action to prevent hospital acquired infections (HAIs). Correct technique that thoroughly cleans all hand surfaces is more important than the cleaning agent. Frequency recommendations need to be tailored to specific needs and workloads. Research indicates poor technique, infrequent handling, and lack of training as contributors to poor hand washing.

Alcohol-based Hand Rubs

• Effective when hands are not visibly soiled, but are more costly than soap and water.

Personal Protective Equipment

• PPE is used when contamination with blood or body fluids is anticipated, which includes disposable gloves, plastic aprons, face masks, safety glasses/goggles/visors, head protection, foot protection, and fluid-resistant gowns.

Sharps Injuries

• Prevention focused on correct sharps disposal, avoiding re-sheathing needles, avoiding removing needles, discarding syringes as a single unit, and avoiding over-filling sharps containers. Management involves following any local policy for sharps injuries.

Aseptic Technique

• Asepsis is the prevention of sepsis, a harmful infection by bacteria. Minimizing risk of introducing pathogens to susceptible sites and preventing pathogen transfer to prevent infection spread.

Isolation

• Isolation can be per room or group. Source isolation is used for infected patients (mainly to prevent airborne transmission via respiratory droplets such as respiratory MRSA, pulmonary Tuberculosis). Protective isolation isolates immunosuppressed patients. Isolation can negatively impact patients psychologically.

Staff Health

• Risks of acquiring/transmitting infection can be minimized through immunization, covering lesions, and restricting non-immune/pregnant staff. Staff should seek advice when suffering from infections, and report accidents/untoward incidents.

Linen Handling and Disposal

• Bed making, linen changing are key techniques. Gloves and aprons are crucial when handling linen.

Waste Disposal

• Clinical waste is high-risk and requires yellow plastic bags prior to incineration. Household waste bags are black.

Spillage of Body Fluids

• PPE (disposable gloves and aprons) is vital, followed by soaking up spills with paper towels and treating areas with hypochlorite solution (e.g., Milton) for several minutes. Clean contaminated areas with warm water and detergent before disinfecting areas. Treat spills as clinical waste and place into yellow plastic bags.

Environmental Cleaning

• Poor hygiene in hospitals can be a significant public health risk as pathogens can survive for long periods in dust, debris, and dirt. Maintaining good hospital hygiene will reduce risks to staff and patients..

Risk Assessment

• Risk assessment guidelines for infection control should be established, which involves no risk of splashing with blood/body fluids means PPE is not required; low or moderate risk of contact/splashing means only gloves and aprons are necessary; high risk means gloves, aprons, gowns, eye/face protection are required.

Body Fluids

• This category includes cerebrospinal fluid, peritoneal fluid, pleural fluid, synovial fluid, amniotic fluid, semen, vaginal secretions, and other fluids containing visible blood (e.g., urine, feces).