HLTH module 3: infection Flashcards
when does an infection occur?
when a microbe or parasite is able to reproduce in or on the body’s tissues
reservoir
the source of infection
direct contact of infection
occurs for microbes in the blood, body secretions or a lesion
what is the cause of syphilis?
treponema pallidum
what is the cause of toxoplasmosis
toxoplasma gondii; results in many neurologic effects
how can indirect contact from injection occur?
involves an intermediate object such as a contaminated food or hand that carry organisms
droplet transmission
can be oral or respiratory and occurs when respiratory or salivary secretions containing pathogens are expelled from the body and then transferred to another person
aerosol transmission
involves small particles from the respiratory tract that remain suspended in the air and travel on air currents, infecting any new host that inhales the particles
vector-borne
occurs when an insect or animal serves as an intermediary host in a disease such as malaria
nosocomial infections
those that occurs in health care facilities such as hospitals, nursing homes, doctors offices, and dental offices
interferons
proteins produced by human host cells in response to viral invasion of the cell; these influence the activity of nearby host cells, increasing their resistance to viral invasion
factors that decrease host resistance
age (infants and elderly), genetic susceptibility, immunodeficiency, malnutrition, chronic disease, severe stress, inflammation or trauma affecting the skin or mucosa, and impaired inflammatory response
pathogenicity
the capacity of microbes to cause disease
virulence
the degree of pathogenicity of a specific microbe
factors that virulence is based on
invasive qualities, toxic qualities, adherence to tissue, and the ability to avoid host defences
toxic qualities
the production of enzymes, exotoxins, and endotoxins that damage host cells
how can microbes avoid host defences?
frequent mutations which cause antibodies to no longer be effective, so the individual is no longer protected
how can microbes adhere to tissues?
by pili, fimbriae, capsules, or specific membrane receptor sites; certain organisms tend to establish infection in particular areas of the body that are hospitable to that microbe
methods for controlling infection
locating and removing the reservoir, blocking the portal of exit of microbes, knowledge of the mode of transmission, adequate cleaning of surrounding (includes sterilization, disinfectants, and antiseptics)
universal precautions
provide the basic guidelines by which all blood, body fluids, and wastes are considered ‘infected’ in any patient regardless of their conditions; two levels (general and specific)
antisepetics
antimicrobial chemicals designed to be used on living tissue, ex. isopropyl alcohol or hand sanitizer
sterilization
complete destruction/removal of all microorganisms by exposure to heat; ex. autoclaving
disinfectants
chemical solutions designed to be used on living surfaces that destroy microorganisms and their toxins
incubation period
the time that the body is exposed to the organism and the appearance of clinical signs, these vary lots; the organism is producing lots until there are sufficient number to cause adverse effects in the body
prodromal period
the period of early symptoms when the infected person may feel fatigued, lose appetite, or have a headache; ‘im coming down with something’
acute period
period when the infectious disease develops fully and the clinical manifestations reach a peak; time varies based on pathogen and host resistance
convalescent period
the period of recovery when signs subside and body processes return to normal
4 stages of infection
incubation period, prodromal period, acute period, and convalescent period
local infection
organism enters the body and remains confined to a specific location
focal infections
pathogen spreads from a local infection to other tissues
systemic infections
infection spreads to other sites and tissue fluids, typically through the circulatory system
septicemia
caused by multiplication of pathogenic organisms in the blood and the cause of sepsis
bacteremia
presence of bacteria in the blood
toxemia
presence of toxins in the blood
viremia
presence of viruses in the blood
mixed infections
several infectious agents concurrently establish themselves at the same site
acute infections
appear rapidly with severe symptoms but are short lived
chronic infections
less severe symptoms than acute infections but persist for a long time
primary infections
initial or first time exposure/infection
secondary infections
follow a primary infection and are caused by a different microbe
subclinical infections
do not cause apparent signs or symptoms although may persist over long periods of time
local signs of infection
generally those of inflammation: red, tenderness, swelling, pain, and warmth (sometimes pus); can also be signs in the respiratory tract such as sneezing or those in the GI tract
when is pus present?
when the infection is caused by a bacteria
systemic signs of infection
fever, fatigue, weakness, headache, and nausea; severe infections can cause neurological effects like confusion, seizures, and a loss of consciousness
how are organisms identified?
by culture or staining techniques, by blood tests, by rapid tests, and radiologic examination
what do blood tests look for in infections?
the number of WBCs; bacterial infections have an increase of WBCs where viral infections have a decrease in WBCs; inflammation also results in high erythrocyte sedimentation rate and C-reactive proteins
leukopenia
decrease in WBCs
leukocytosis
increase in WBCs
rapid tests
based on metabolic and serologic characteristics of the organisms and provide quick and accurate identification of the pathogen
why is proper use of antibiotics important?
because improper use can cause resistant organisms to dominate an infection that may have had few resistant organisms at the onset; the weaker ones are thus killed and the stronger ones survive
guidelines for effective drug therapy
the drug should be taken at 24 hour interval, the drug should be taken until it is completely used, fluid and food intake must be followed, use the drug that has the smallest impact on resident flora, have a complete drug and allergy history, and not using antibacterials against viruses
antimicrobials
classified by the type of microbe against which the drug is active; includes antibiotics, antivirals, and antifungals
antibiotics
can kill or inhibit the growth of microorganisms
bactericidal drugs
drugs that kill bacteria
bacteriostatic drugs
drugs that inhibit bacterial reproduction and rely on the host to ultimately destroy the bacteria
broad spectrum
refers to antibacterials that are effective against both gram-negative and gram-positive organisms
narrow-spectrum agegents
act against either gram-negative or gram-positive microorganisms
first-generation vs second-generation drugs
first-generation are the original drug class and second-generation are the later, improved version of the same drug group
five ways that antibacterial drugs act
interference with cell wall synthesis, increase permeability of bacterial cell membrane, inference with protein synthesis, interference with nucleic acid synthesis, and disrupting critical metabolic processes
common problems with antibacterial drugs
they often cause allergic reactions, mild or severe and interfere with the GI tract
how do antiviral drugs work?
they decrease the reproduction of viruses inside the host cell or prevent the attachment/entry into a cell, but typically cannot destroy the virus
how do antifungal drugs work?
by interfering with mitosis in fungi or increasing fungal membrane permeability; most are applied topically to the skin
antiprotozoal agents
target eukaryotic cells and can be toxic to humans; similar to antifungal drugs
antihelminthic agents
similar to antifungals and antiprotozoals in that they target a eukaryotic organism; suppress a metabolic process in the helminth or inhibit movement
influenza
a viral infection that affects. both the upper and lower respiratory tracts; usually mild but is commonly complicated by secondary bacterial infections such as pneumonia
classification of the influenza virus
RNA virus of the myxovirus group; three subgroups A, B, and C
what is the most prevalent influenza subgroup
A; difficult to control as it goes through many mutations
how are new influenza vaccines produced?
by using viruses grown in a cell culture rather than eggs
where do most new influenza strains develop?
southeast asia
how are influenza vaccines administered?
by intranasal spray (live vaccine) or intramuscular injection (inactivated or killed)
how is influenza virus transmitted?
by respiratory droplet or by contact with a contaminated object
where does the influenza virus persist?
in the cells of the respiratory mucosa; here it causes inflammation and necrosis of the tissue
why does influenza cause people to be susceptible to secondary infections?
because the respiratory mucosa is necrosised, making it vunerable to other microbes entering the body
general symptoms of influenza
a sudden, acute onset with fever and chills, marked by malaise, headache, muscle aching, sore throat, drug cough, and nasal congestion
