Infectious Disease Flashcards
What is bacteria?
single-celled microorganisms, examples are Streptococcus, Staphylococcus, Enterococcus
What is a virus?
Need a host cell to live and grow, examples are the common cold, AIDS, hepatitis, mononucleosis
What is mycoplasma?
neither a bacteria or a virus, does not require a host cell, does not have a cell wall which makes it resistant to antibiotics, usually infects the respiratory tract, examples pneumonia, pharyngitis, urethritis
What is Rickettsiae?
a form of bacteria that need a host cell to live and grow like a virus, transmitted through the bite of an arthropods, examples are Rocky Mountain Spotted Fever, typhus
What is fungi?
classified as either molds or yeasts, can live in a wide variety of environments and do not necessarily need a host, examples are candidiasis, tinea pedis, histoplasmosis
What is a parasite?
organism that lives on or in another organism and obtains nourishment, examples are hookworms, Giardia, Malaria
What is a resevoir?
Place where the causative agent can survive and may or may not multiply
Examples: human body, soil, water, equipment
Reservoirs can be carriers meaning they do not have symptoms but carry an active pathogenic microorganism
What is a portal of exit from the reservoir?
Path that allows the causative agent to escape from the reservoir
Common human portals include the respiratory, gastrointestinal, genitourinary systems, and the skin and mucous membranes
Blood, sputum, emesis, stool, urine, wound drainage, genital secretions
Methods of transmission
A mode of transmission by which the causative agent travels from the reservoir to the susceptible host
- Contact: Occurs with direct, indirect, or droplet contact
- Airborne: expelled from an infected person and suspended in the air in droplets no larger than 5 microns
- Vehicle: maintained on a nonliving object such as food, water, blood
- Vector-borne: carried by a living intermediate host such as a mosquito or tick
What is the portal of entry?
The path by which the infective organism enters the new susceptible host
Usually the same as the portal of exit
What makes a host susceptible?
Weakened defenses put the host at increased risk of infection
Stages of the infective process
- Incubation period
- Prodromal stage
- Acute illness
- Convalescent stage
What happens in the incubation period?
organism is establishing itself, no symptoms, the infected person is contagious
What happens in the prodromal stage?
symptoms begin to appear and are usually nonspecific
What happens during the acute illness?
the infective organism is growing and spreading rapidly, inflammatory and immune response, development of more specific symptoms
What happens in the convalescent stage?
damaged tissue begins to heal and symptoms resolve
Defense mechanisms
Human beings have many defenses against infectious disease including physical, chemical, and immune mechanisms
Examples include: skin, mucous membranes, respiratory cilia, secretion of oil and moisture, normal flora, chemical secretions
The immune response
Humoral response involves the antigen-antibody reactions
Cellular response involves the reaction of the WBCs
Infection prevention and control
The single most important factor in the control and prevention of infection is good hand hygiene
-Compliance with hand hygiene by healthcare workers is less than 50%
-Alcohol based agents are more effective for hand antisepsis than soap and water
Private rooms
Use of PPE
Proper disposal of soiled equipment including linens
Use of isolation precautions including neutropenic precautions
Immunization programs
Patients with increased susceptibility to infections
Very old and very young
impaired skin, aspiration, poor nutrition
Immunodeficient
cancer, HIV
any client with recurrent infections such as otitis media, pneumonia, candidiasis should be evaluated for immune dysfunction
HIV, secondary immune deficiency
Occurs when the immune system is damaged and unable to mount an appropriate immune response
Causes include chemotherapy, age, malnutrition, burns, malignancy, HIV/AIDS
Cellular level of HIV
HIV devastates the hosts immune system by invading CD4+ T cells (T-helper cells)
T cells start and stop the immune process
If unable to initiate an immune response due to loss of T cells then even benign infections can be deadly
HIV is an RNA or retrovirus. To reproduce it must take over a cells DNA where it then directs proteins and enzymes to replicate the HIV portion and create more HIV particles
HIV epidemiology
There are 36.9 million people living with HIV/AIDS
The majority are women and under the age of 15
Sub-Saharan Africa is home to 71% of the world’s HIV/AIDS population
-This is due to heterosexual transmission, lack of condom use, migration patterns, mother-to-infant transmission
-Poverty, lack of health care resources, lack of prevention education
In the US there are about 1.2 million people with HIV
-One in eight are unaware they are infected
-Groups at greatest risk in the US are gay and bisexual males, heterosexuals especially women, IV drug users
HIV transmission routes
Transmission is by contact with infected body fluids such as blood, semen, vaginal secretions, breast milk
Transmission does not occur through sweat, tears, saliva, urine, emesis, sputum, respiratory droplets, or feces
When can HIV be transmitted?
For transmission to occur there must be a sufficient viral load and a susceptible host
Viral loads are high in the first few months after initial infection and during an AIDS-related illness
Prolonged or repeated exposure to infected fluids greatly increases the risk of transmission
Clinical manifestations of HIV
Vary and may affect almost any organ in the body
Specific clinical manifestations are related to opportunistic infections
As CD4+ counts drop to <200 cells/uL the incidence of opportunistic infections accelerates rapidly
Malignancies are common
Diagnosis of HIV
Rapid HIV test
Western Blot tests
CDC recommends HIV screening as a routine part of medical care
Rapid HIV test
Rapid HIV tests screen for HIV antibodies and provide results in 15 to 60 minutes
- Enables easy post-test counseling
- Negative result require no further testing, positive result confirmed by Western Blot
Western Blot test
Western Blot tests screen for HIV antibodies and provide results in 1 to 3 days
- 99% accurate
- Greater sensitivity and specificity
Progression of AIDS diagnosis
Progression to AIDS is confirmed with a CD4+ T cell count of <200 cells/uL and/or documentation of an AIDS defining condition
-Mycobacterium avium complex, Pneumocystis jiroveci, Histoplasmosis that has spread, etc.
HIV treatment
The virus mutates frequently which makes vaccine development and even treatment difficult
Antiretroviral drugs (HAART)
Treatment of opportunistic infections
Antiretroviral drugs to treat HIV
Antiretroviral drugs are the cornerstone of treatment, HAART
-Treatment begins when HIV RNA levels >55,000 copies/mL or <350 CD4+ T cells/uL
-Prevents viral replication
Adherence to the treatment plan is essential to avoid drug resistance. Noncompliance can be caused by:
-Complexity of dosing
-Side effects include fatigue, anorexia, diarrhea, N&V
-Socioeconomic issues
Nursing management for HIV
Education about -Prevention -Transmission -Medication regime -Prevention of opportunistic infections -When to see the doctor -Laboratory testing Emotional care Referrals for social services Counseling should be open, honest and nonjudgmental
Oral candidiasis (thrush)
Fungal opportunist infection that affects virtually all clients with AIDS
Small amounts of the candidal fungus are present in the mouth in healthy people
Oral candidiasis creates white patches in the mouth that can extend into the esophagus and stomach
Oral lesions provide a portal for candidiasis into the bloodstream causing a life-threatening fungal infection
Cause pain and difficulty swallowing which further impairs nutrition
Treatment is Mycostatin oral rinse
Monitor oral intake ability
Pneumocystis Jiroveci Pneumonia
Fungal infection that proliferates in the alveoli causing bronchial consolidation
S&S include: mild, dry cough, tachypnea, fever, SOB, decreased O2 sats
Chest x-ray shows bilateral patchy infiltrates
Sputum culture
Treatment is Bactrim and corticosteriods
It does not respond to antifungals
If untreated can lead to respiratory arrest and death
Monitor ABGs, pulse oximeter, respiratory rate and quality, lung sounds, may need supplemental oxygen or ventilator support