Bacteriology 8/27 Chp. 3

define Healthcare-associated infections (HAIs)

infections from a healthcare setting while receiving care

define Community-acquired infections

infections from a community area

define Iatrogenic infections

specific subset of infections acquired directly after a medical or surgical procedure

define Surveillance (in healthcare)

ongoing, systematic collection, analysis, and interpretation of data surrounding a disease or health event to monitor trends.

define Baseline data

The initial measurement of information collected prior to the start of an intervention. It is used to determine if a problem exists, show change over time, and monitor progress.

define prevalence

The number of cases of a disease that occur at a given moment in time or during a specific period within a given population.

define case definition

A set of standard criteria used by epidemiologists to classify whether a person has a particular disease, syndrome, or health condition.

define antiogram

A compiled annual report showing the patterns of sensitivity and resistance of local bacterial isolates to various antimicrobial agents, used by clinicians to guide empiric therapy.

define molecular epidemiology

The analysis of molecules (such as proteins and nucleic acids) to detect, identify, and characterize microorganisms, generating isolate-specific markers to assess epidemiologic relatedness

define standard precautions

Infection control practices safety-mandated under the assumption that all patients and specimens are potentially infectious, requiring proper hand hygiene, PPE, and safe disposal of waste.

define the acronym for HAIs in acute care hospitals: SSI

Surgical Site Infection

define the acronym fro HAIs in acute care hospitals: CLABSI

Central Line Associated Bloodstream Infection

define the acronym fro HAIs in acute care hospitals: CAUTI

Catheter Associated Urinary Tract Infection

define the acronym fro HAIs in acute care hospitals: VAP

Ventilator Associated Pneumonia

What rule determines if an infection is hospital-acquired (HAI) versus community-acquired upon admission?

The infection must occur more than 48 hours after arrival at the hospital and must not have been incubating in the community prior to admission.

What are four common causes of HAIs and iatrogenic infections?

1. Contaminated instrumentation

2. Increased use of antimicrobial agents

3. Breaks in aseptic technique

4. Poor hand hygiene

Which foodborne and waterborne pathogens are frequently identified in public health and community settings?

Giardia lamblia, Cryptosporidium, Salmonella, Shigella, and Campylobacter

define MSSA (Methicillin-Sensitive Staphylococcus aureus)

Sensitive to first-line oxacillin/methicillin antibiotics.

define MRSA (Methicillin-Resistant Staphylococcus aureus)

Resistant to oxacillin/methicillin, requiring alternative treatments.

What is VRSA and why is it a major current concern?

Vancomycin-Resistant Staphylococcus aureus. Vancomycin is a highly potent IV drug used to treat MRSA, so resistance to it represents a severe clinical threat.

What causes Clostridium difficile infections in hospital patients, and what are the clinical symptoms?

Long-term or broad-spectrum antibiotic use wipes out the normal GI flora, allowing C. difficile to colonize and produce toxins that cause severe diarrhea.

What opportunistic pathogens are of greatest concern in extended care and home care settings?

Pseudomonas aeruginosa, Candida, Staphylococcus aureus (including MRSA), Vancomycin-Resistant Enterococci (VRE), Acinetobacter spp., and Clostridium difficile.

What is the difference between total surveillance and targeted surveillance?

Total surveillance: Monitoring and recording all infections across the entire healthcare facility.


Targeted surveillance: Focusing close watch only on specific high-risk, high-volume, or high-consequence procedures/infections.

What is an LIS and what is its role in infection control?

Laboratory Information System. It is computer software that processes, stores, and manages laboratory data. It is used to run daily positive culture reviews to spot infection trends.

Why must the clinical laboratory stay informed about ongoing community health events?

1. To acquire necessary media or reagents ahead of surges.
2. To proactively educate providers on proper specimen collection/transport.

3. To ensure adequate laboratory staffing for high testing volumes.

What are the acceptable baseline rates for blood culture contamination in hospitals?

The contamination rate should remain below 3%. Rates higher than 3% indicate a need for refresher training on aseptic collection for nurses and phlebotomists.

What are the 9 sequential steps of an outbreak investigation?

1. Establish a case definition


2. Confirm that an outbreak exists


3. Find additional cases


4. Gather info (person, place, time; epidemiologic curve)


5. Form a hypothesis


6. Test the hypothesis (using control groups)


7. Establish interventions to stop the outbreak


8. Evaluate the effectiveness of the intervention


9. Communicate the findings

What strain typing technique, used since the 1980s, separates enzyme-digested chromosomal fragments of bacteria electrophoretically to check for relatedness?

Pulsed-Field Gel Electrophoresis (PFGE)

When do air-quality-related infections typically occur in healthcare settings, and what process must be performed before culturing the air?

They typically occur during construction. An Infection Control Risk Assessment (ICRA) must be performed before any decision to culture the air is made.

What are the two main methods for collecting air samples?

High-volume air sampling (the preferred method) and settle plates (exposing agar plates to the air).

How often does the CDC recommend performing water cultures of water and dialysis fluids in hospitals?

at least once a month

What are Class A1 diseases, and how must they be reported?

Extreme infectious diseases and bioterrorism threats (such as anthrax, botulinum, diphtheria, plague, smallpox, and rabies) that must be reported to public health authorities as soon as they are suspected or identified.

define emerging pathogens?

Newly recognized agents that have not been seen before (e.g., COVID-19, SARS, West Nile virus).

define re-emerging pathogens

Pathogens that were once thought to be eliminated or eradicated but have reappeared (e.g., smallpox).