Summary - IPC Module 2 Flashcards
Normal Flora
NF = microbes living in/on body; cause no harm as long as they stay in expected site – on outer surfaces or areas exposed to outside
Found: skin and mucous membranes (GI, respiratory, genital tracts)
Composition varies depending on body site:
large intestine: most NF; mainly E.coli
upper respiratory tract: second most NF; mainly viridans streptococci
skin: less NF; mainly staphylococci
NF same from person to person for a given site
Factors that can affect NF:
excessive moisture on skin: ↑ staphylococci (ring, watch, gloves)
antibiotic therapy: kills sensitive microbes; resistant microbes can take over
Normally Sterile Areas – inside the body
– blood, CSF (spinal fluid), tissue, fluids that surround organ
contamination
unexpected microbes at body site; do not grow; no harm e.g. mouth bacteria on hands
colonization
unexpected microbes at body site; DO grow; no harm initially … maybe later
e.g. fecal bacteria colonized in upper resp. tract:
if go away → end of story
if don’t go away → may cause disease
Staphylococcus aureus / MRSA in the nares of “carrier” - passed to susceptible host
infection/disease:
unexpected microbes; Do grow; Do cause harm. Terms usually synonymous, but sometimes there is a difference:
infection: host has pathogen; no symptoms; (e.g. invasion by HIV)
disease: host has pathogen AND symptoms (e.g. AIDS resulting from HIV infection)
pathogen
disease-causing microbe
etiology
cause of a disease (HIV etiological agent of AIDS)
virulence
degree of pathogenicity of a microbe; determined by virulence factors
nonpathogen
microbe that cannot cause disease (very few)
lowgrade/opportunistic pathogen
microbe that does not usually cause disease; only if defenses of host ↓
Toxins (exotoxins & endotoxins)
produced by some bacteria
exotoxins: G+ bacteria; released from intact bacteria; carried away from infection site; specific: attack target tissue (e.g. tetanus toxin → CNS)
endotoxins: G- bacteria; part of cell wall; released when cell wall disrupted; carried away from infection site; nonspecific: effect more generalized (fever, malaise, ↓ BP), can lead to destruction of organs and fatal shock (e.g. Hamburger disease from E. coli 0157 can lead to destruction of the kidneys)
The Chain of Infection
Reservoir > Means of Transmission > Susceptible Host
Reservoirs of Infectious Microorganisms (reservoir = source)
- humans: with infections or carriers; main reservoir for human infections
- animals
- nonliving: soil; H20; because H20 is a reservoir, flowers may not be allowed on some wards
- carrier = person who
harbors pathogenic microbes but shows NO SIGNS of infection; can pass microbes on to others
-convalescent carrier: person had disease; symptoms now gone; microbes still in body
-chronic carrier: 6 months after symptoms gone, microbes STILL in body
Transmission of Infectious Microbes
- Contact Transmission - direct (person to person) , indirect(reservoir to inanimate object to host), droplet (large “globs of mucous that contain microorganisms)
- Vehicle Transmission - reservoir - food/water, droplet nuclei (very small, travel long way), infected solutions (blood transfusions)
- Vector Transmission - reservoir → insect → host
(not usually a form of health care facility transmission)
e.g., malaria, Rocky Mountain spotted fever, Hanta, West Nile
Susceptible Host
Factors that influence host susceptibility to infectious diseases:
age (the young and the elderly more susceptible)
general health: poor nutrition, pre-existing infection, underlying disease all make host more susceptible
chemotherapy, radiation, antibiotics alter immune status
surgery, anaesthesia, insertion of catheters … more susceptible infectious dose
Portals of Entry of Infectious Microorganisms
Skin: if intact, most microbes can’t penetrate; can get in:
via hair follicles/sweat glands
if skin excessively moist
if skin broken
Mucous Membranes: different mucous membranes susceptible to penetration by different microbes. e.g. genital mucosa: microbes that cause STDs (gonorrhoea, syphilis, herpes, chlamydia, HIV/AIDS)
Placenta: most microbes can’t cross ∴ fetus protected from mom’s bugs;
some exceptions: microbes that cause rubella, Hepatitis B, HIV/AIDS
Parenteral: microbes get in through a “poke” (IV, intramuscular injection, insect bite … any means that bypasses GI tract)
Signs and Symptoms of Infection
- Fever
- Lymph Node Swelling
- Inflammation
Terms Used to Describe Infectious Diseases
acute disease - symptoms develop rapidly and disease runs its course quickly
chronic disease - symptoms develop slowly and disease slow to disappear
latent disease - periods of inactivity before symptoms appear or between attacks
localized infection - confined to one area of the body
focal infection - confined to one area, but pathogens or their toxins migrate to other areas
systemic infection - pathogen spreads (disseminates) to multiple organs or tissues
septicemia- pathogens (bacteria or viruses) present and multiplying in blood
bacteremia- bacteria present in blood but not multiplying
viremia - viruses present in blood but not multiplying
toxemia - toxins in blood
exogenous infection - microbes come from outside the host
endogenous infection - microbes come from within the host’s own body
primary infection - infection of a previously healthy person
secondary infection - follows a primary infection; caused by a different microbe;
e.g. bacterial infection following a viral infection, fungal (yeast) infection following antibiotics
Nosocomial Infections
- Infection acquired as result of stay in hospital or institution
- Rate in hospital patients: 5-15%
- Contributing Factors:
hospital microbes: lots of pathogens, antibiotic-resistant strains, warm and moist environment promotes their growth
compromised patients: immune system depressed due to illness or treatment
transmission of microbes facilitated: patients in close proximity; staff go from patient → patient → patient; patients have openings into normally protected areas of the body (catheters, incisions) - Top 3 nosocomial infections, in order of occurrence:
urinary tract infections
surgical wound infections
pneumonia - Surgical wounds often infected with Staphylococcus aureus; bacteria can come from health care workers who are staph carriers (carry in nasal passages; no symptoms) → transmitted to patient’s open tissue. Every health care worker should consider himself a staph carrier … keep hands away from nose… wash after touching nose for any reason
Antibiotics
- Definition – substance produced by a microorganism (often a fungus) that inhibits the growth of, or kills another microorganism (bacteria)
- Antibiotic testing – done in lab: organism on plate, add antibiotic discs, incubate
determine which antibiotics work (organism is susceptible (sensitive) and will not work resistant (insensitive) - Current “super bugs” – resistant to many antibiotics – infection not necessarily worse – just harder to treat
MRSA (Methicillin Resistant Staphyococcus aureus)
VRE (Vancomycing Resistant Enterococcus)
Clostridium difficle (C. diff, CDAD)
Antibiotic-Resistant Bacteria (ARO’s MDRO’s)
Of particular concern in health care facility: MRSA (methicillin-resistant Staphylococcus aureus) and VRE (vancomycin-resistant Enterococcus).
Clostridium difficle an emerging problem as it is resistant to treatment + is spore former and difficult to destroy when environmental surfaces are contaminated.
Why of concern:
if patient gets infection, may not be an effective antibiotic for treatment
drug-resistant strains may spread to others in the health care facility … real trouble!
Miscellaneous Methods of Controlling Infection
Silver impregnated bandages
Phages (viruses that infect specific bacterial cells and destroy them)
Infection Prevention and Control (IPC)
Organization: Alberta Health Services will oversee programs in regions and health care facilities
Health care facilities required to monitor nosocomial infections and implement infection prevention and control programs
Infection Prevention and Control Practitioners (IPC’s) are specially trained staff, who have added IPC to their professional credentials
-participate in development of policies and procedures both nationally and provincially
-implement policies and preventative measures
-determine patient placement (isolation)
-educate staff
-monitor and report outbreaks
Website for Infection Prevention and Control Strategies
Epidemiology: study of incidence, source and spread of disease
