Chapter 12: Healthcare Epidemiology: Nosocomial Infections and Infection Control

Society for Healthcare Epidemiology of America (SHEA) (4 goals)
1. Follow standardized procedures to prevent the spread of communicable diseases
2. Enhancement/Prevention
3. Programs
4. Policy, education


Hospital associated Infections (HAI)
– acquired within hospitals (nosocomial)
– The pathogens live on and in healthcare professionals, visitors, and the patient themselves
– The pathogens are usually drug-resistant and multi-drug resistant strains.
Community acquired Infections (CAP)
infections are acquired outside healthcare facilities
Iatrogenic Infections
(physician induced) diseases resulting from medical/surgical treatments (post surgical wounds, caused by a healthcare worker)
Gram-positive cocci associated with HAI (3)
1. Staphylococcus aureus (MRSA)
2. Enterococcus (VRE)
3. Coagulase- negative staphylococcus


Gram-negative cocci associated with HAI (4)
1. Pseudomonas aeruginosa
2. Escherichia coli (ESBL)
3. Enterobacter sp. (Amp C gene)
4. Klebsiella pneumoniae (ESBL)


Process of selection (4)
1. Indigenous flora contain many susceptible organisms, few resistant strains.
2. Antibiotics kill off susceptible organisms.
3. Only a few resistant strains are alive.
4. Decreased competition for nutrients and space, the resistant organisms multiply and become predominant in the patient’s indigenous flora.
Five Most Common Sources of HAI
1. UTI’s
2. Surgical site infections
3. Lower respiratory tract infections
4. Bloodstream infections (septicemia)
5. Clostridium difficile (AAD-enterotoxin, PMC-cytotoxin)


12 Steps to Prevent Resistance: Prevent Infection (1-2)
Step 1: vaccinate
Step 2: Get the catheters out
12 Steps to Prevent Resistance: Diagnose and Treat Effectively (3-4)
Step 3: Target the pathogen
Step 4: access the experts
12 Steps to Prevent Resistance: Use Antimicrobials Wisely (5-10)
Step 5: Practice antimicrobial control
Step 6: use local data
Step 7: Treat infection NOT contamination
Step 8: Treat infection, not colonization
Step 9: Know when to say “no” to vancomycin
Step 10: Stop antimicrobial treatment
12 Steps to Prevent Resistance: Prevent Transmission (11-12)
Step 11: isolate the pathogen
Step 12: break the chain of contagion
Patients Most likely to Develop HAI (7)
1. Elderly
2. Women in labor and delivery
3. Premature infants and newborns
4. Surgical and burn patients
5. Diabetic and cancer patients
6. Patients receiving treatment with steroids, anticancer drugs, radiation, and antilymphocyte serum ( or gamma globulin for immunosuppression in organ transplant patients)
7. Immunosuppressed or host defense mechanisms are not functioning properly
Ignaz Semmelweis:
Vienna General Hospital, in the 1840s, puerperal or childbirth fever, a bacterial infection of the female genital tract after childbirth, was taking the lives of up to 30% of women who gave birth in hospitals. He ordered students to WASH THEIR HANDS with chlorinated lime before examining their patients, as a result maternal death rate was reduced from 12% to 1% in two years time.
Joseph Lister
In 1866 he introduced carbolic acid as an ANTISEPTIC, to kill airborne bacteria and prevent their transmission into wounds from the air of the operating
Three major causes of HAI’s are
1: drug resistant bacteria
2: the failure of healthcare personnel to follow infection control guidelines
3: increased number of immunocompromised patients
Infection Control
numerous measures taken to prevent infections from occurring in healthcare settings (designed to break chain of infection)
Aseptic techniques
help break the chain of infection
Medical asepsis
involves procedures/practices that help reduce transmission of pathogens (clean technique to exclude pathogens)
Spalding Classification of Instrument Items for Patient Care (3)
System of classifying instruments and items for patient care; according to the degree of risk for infection, this system is used to determine how items are disinfected or sterilized; 3 categories: Critical, Semicritical, Noncritical
items at high risk for infection if they are contaminated with any microbe, items must be sterile (surgical instruments)
items that come that contact mucous membranes or nonintact skin require high-level disinfection, (probes, scopes)
Items that come in contact with intact skin, but not mucous membranes (crutches)
Alcohols: Hospital Disinfectants
– Noncritical
– Cidal for bacteria, TB, fungus, viruses, NOT spores
– disinfect thermometers, external surfaces, stethoscopes, endoscopes
– 60%-90% (ETOH,isopropyl, benzyl)
Chlorine compounds: Hospital Disinfectants
– Noncritical
– disinfect countertops, floors, blood spills, needles, syringes, water treatment
Quaternary ammonium cmp: Hospital Disinfectants
– Noncritical
– Clean floors, walls, furniture
Gluteraldehyde: Hospital Disinfectants
– Semicritical
– disinfect endoscopes, tubing, dialyzers, anesthesia, respiratory equipment
Peracetic acid & H2O2: Hospital Disinfectants
– Semicritical
– disinfect hemodialyzers
Iodine: Hospital Disinfectants
– Noncritical
– Antiseptic usage (patient tissue)
– Disinfect thermometers, endoscopes, rubber stoppers
– Povidine, Wescodyne, betadine, Isoldine, Toprep, Surgidine
Peracetic acid: Hospital Disinfectants
– disinfects automated machines
– chemically sterilize immersible medical instruments, including endoscopes & arthroscopes
Standard Precautions apply to (4)
1) blood
2) all body fluids, secretions, and excretions except sweat, regardless of whether or not they contain visible blood
3) nonintact skin
4) mucous membranes.
– Standard Precautions are designed to reduce the risk of transmission of microorganisms from both recognized and unrecognized sources of infection in hospitals
Personal Protective Equipment: “PPE” (5) Standard Standard Precautions
gloves, gown, eye, mask, face shield
Patient Care Equipment (3)
Standard Precautions

Used /soiled, Reusable equipment, Single-use items
Environmental Control (2)
Standard Precautions

Routine cleaning/ disinfection, Linen exposure
Occupational and Blood borne Pathogens (2)
Standard Precautions

using needles/syringes /scalpels/sharp objects, Use mouthpieces
Three types of Precautions: (3)
Transmission- Based Precautions and Patient Placement

1. Airborne precautions
2. Droplet precautions
3. Contact precautions
Five routes of pathogen transmission:
1. Contact (direct/indirect)
2. Airborne
3. Droplet
4. Vehicular
5. Vectors
Airborne Precautions
Airborne Precautions are designed to reduce the risk of airborne transmission of infectious agents (TB).

occurs by dissemination of either airborne droplet nuclei (small-particle residue [5 ┬Ám or smaller in size]

evaporated droplets that may remain suspended in the air for long periods of time) or dust particles containing the infectious agent.

Therefore, special air handling and ventilation are required to prevent airborne transmission.(negative air pressure rooms

Droplet Precautions
Droplet Precautions are designed to reduce the risk of droplet transmission of infectious agents (bacterial meningitis, whooping cough, strep throat, influenza).

Droplets are generated from the source person primarily during coughing, sneezing, or talking and during the performance of certain procedures such as suctioning and bronchoscopy.

Transmission via large-particle droplets requires close contact between source and recipient persons, because droplets do not remain suspended in the air and generally travel only short distances, usually 3 ft or less, through
the air.

Contact Precautions
Contact Precautions are designed to reduce the risk of transmission of microorganisms by direct or indirect contact.

Direct-contact transmission involves skin-to-skin when personnel turn patients, bathe patients, or perform other patient-care activities that require physical contact

Indirect-contact transmission involves contact with a contaminated intermediate object, usually inanimate, in the patient’s environment.

Contact Precautions apply to specified patients suspected to be infected or colonized MRSA, VRE, RSV, C.difficile

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