09-Nosocomial Infections and Sterilization/Disinfection

Comprehensive vocabulary flashcards covering definitions, methods of spread, risk factors, and physical/chemical sterilization and disinfection procedures based on the microbiology lecture.

Nosocomial Infections

Also known as hospital-acquired infections, these are infections that develop during a hospital stay, were not present in latent form at the time of admission, and typically appear after $48\text{ hours}$ of admission.

National Nosocomial Surveillance System (NNSR)

The reporting system used to track and monitor the epidemiological situation of nosocomial infections within hospitals.

Intrinsic risk factors

Patient-related factors that increase the risk of nosocomial infections, such as old age, severe underlying disease, and immunosuppressed conditions.

Extrinsic risk factors

Institutional or procedural factors that increase infection risk, including invasive interventions, prolonged hospitalization, and prolonged surgery.

Droplet infection

Spread of pathogens via particles larger than $5\text{ }\mu\text{m}$ that float briefly within $1\text{ m}$ when coughing or sneezing, such as B. pertussis or N. meningitidis.

Sterilization

A process that removes, kills, or deactivates all forms of life, including microorganisms like fungi, bacteria, spores, and viruses; the resulting object is considered sterile or aseptic.

Disinfection

A process of eliminating vegetative forms of pathogen microorganisms (except bacterial spores) from inanimate objects to reduce the risk of infection.

Microbicidal

An inhibitory effect that destroys microbes, such as bactericidal, fungicidal, or virucidal actions.

Microbistatic

An inhibitory effect that prevents the growth of microbes without necessarily killing them, such as bacteriostatic or fungistatic actions.

Hot air sterilization

A dry heat physical procedure typically performed in a drying oven at $160^{\circ}\text{C}$ for $2\text{ h}$ or $135\text{--}145^{\circ}\text{C}$ for $3\text{ h}$, used for metal and glass objects.

Tyndallization

A wet heat sterilization method involving heating at $80^{\circ}\text{C}$ for $30\text{ min}$, followed by $24\text{ h}$ at room temperature, repeated three times to kill endospores.

Pasteurization

A disinfection-only wet heat process involving heating at $63^{\circ}\text{C}$ for $30\text{ min}$.

Autoclaving

Complete sterilization using wet heat in a steam-heated system under an overpressure of $1\text{ atm}$ at $121^{\circ}\text{C}$ for $20\text{ min}$; for prions, it requires $135^{\circ}\text{C}$ for $20\text{ min}$.

Filtration sterilization

The separation of microbes from liquids using membrane filters (such as nitrocellulose) with controlled pore sizes to filter bacteria or viruses.

UV irradiation

Radiation between $100\text{--}300\text{ nm}$ that kills vegetative microbes on surfaces and in the air by causing DNA damage (thymine dimers), though it has poor penetrability.

Gamma irradiation

Ionizing radiation from a $\text{Co}$ isotope source with high penetrability used to sterilize plastic medical tools and hermetically sealed materials by causing DNA strand breakage and protein denaturation.

Gaseous Sterilization agents

Chemical substances used in gas form for sterilization, including Ethylene oxide, Formaldehyde, Nitrogen dioxide ($\text{NO}_2$), and Ozone.

Ethyl alcohol (disinfection concentration)

A disinfectant that reaches its maximum efficacy when used in a $70\%$ aqueous solution.

MRSA

Methicillin-resistant Staphylococcus aureus, a common nosocomial pathogen often carried in the nose of medical personnel.

Sepsis mortality rate

In the context of nosocomial infections, this condition has a mortality rate of $20\text{--}40\%$.