Microbiology Key Terms
Master these terms for the BSMIC domain. Terms are grouped by topic area.
Pathogenic Organisms
Bacteria
Single-celled microorganisms, some pathogenic, classified by shape, Gram stain reaction, and oxygen requirement.
Gram-positive vs. Gram-negative
A classification based on bacterial cell wall structure and Gram stain reaction, relevant to antibiotic selection.
Spore-forming bacteria
Bacteria (such as Clostridium and Bacillus species) capable of forming highly resistant spores that survive disinfection and require sterilization for elimination.
Virus
A non-cellular infectious agent that requires a host cell to replicate.
Fungus
A eukaryotic organism (yeasts, molds) that can cause infection, particularly in immunocompromised patients.
Prion
An infectious misfolded protein resistant to standard sterilization methods, requiring specialized processing protocols.
Chain of Infection
Infectious agent
The pathogen capable of causing disease.
Reservoir
The environment where a pathogen naturally lives and multiplies (human, animal, or environmental).
Portal of exit
The route by which a pathogen leaves its reservoir (e.g., respiratory secretions, blood).
Mode of transmission
How a pathogen travels from reservoir to a new host (contact, droplet, airborne, vehicle, vector).
Portal of entry
The route by which a pathogen enters a new susceptible host (e.g., a surgical incision).
Susceptible host
An individual with insufficient immunity to resist infection by a given pathogen.
Surgical Site Infection Concepts
Bioburden
The number of microorganisms present on a surface or item before decontamination.
Nosocomial (healthcare-associated) infection
An infection acquired during the course of receiving healthcare, not present at admission.
Surgical site infection (SSI)
An infection occurring at or near a surgical incision within a defined postoperative period.
Resident flora
Microorganisms normally and consistently present on the skin, not easily removed by routine handwashing.
Transient flora
Microorganisms temporarily present on the skin, typically acquired through contact and more easily removed.
Antimicrobial Concepts
Antisepsis
The use of antimicrobial agents on living tissue to reduce microbial presence.
Disinfection
The reduction of microorganisms on inanimate surfaces or objects, not reliably effective against bacterial spores.
Antibiotic prophylaxis
Preventive antibiotic administration timed before incision to reduce surgical site infection risk.
Antibiotic resistance
The ability of a microorganism to survive exposure to an antibiotic that would normally inhibit or kill it.
Standard Precautions
Standard precautions
Infection control practices applied to all patients regardless of known infection status, including hand hygiene and PPE use.
Personal protective equipment (PPE)
Barrier equipment (gloves, gowns, masks, eye protection) used to reduce exposure to infectious material.
Bloodborne pathogen
An infectious microorganism present in blood that can cause disease (e.g., HIV, hepatitis B, hepatitis C).
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