Infectious disease Flashcards
Infectious disease S/S
- fever-chills
- malaise, sweating, nausea, vomiting
- inc leukocyte reaction
- Pain
- rash/skin lesions
- red streaks
- inflammation lymph nodes/joints
Special consideration- elderly
- aging immune system
- chronic diseases
- extrinsic factors
- underreport symptoms- atypical symptoms
what do we see in the aging immune system?
- decr naïve Tcells
- incr memory Tcells
- decr proinflammatory cytokines
- decr cell mediated immunity
Infection
Process of organism forming a parasitic relationship wi the host
- -organism invades, producing an immune response by host
- -cellular damage results from production of toxins, competition with host’s metabolism
colonization
microorganisms live together in host’s tissues with the host being asymptomatic
transmission of infectious pathogen depends on:
- pathogen
- environment
- susceptibility of host
successful transmission may lead to…
- destruction of pathogen (first line of defense-intact skin/mucous membrane)
- subclinical infection-rise in antibody titer, but no clinical symptoms
- infectious disease with one or more clinical symptoms
incubation period
- time between initial entrance of pathogen into host to appearance of disease symptoms
- varies from few days –> several months
latent infection
- replicated pathogen remains dormant in host
- may be up to years before becoming active
communicable period
- Pathogen can be shed and passed from host to host
- directly vs. indirectly
- varies with pathogen and disease
- usually before S/S appear and may continue through disease and even extend into convalescence stage
- asymptomatic host can pass the pathogen
Types of organisms: Viruses
- RNA or SNA nucleus with protein coat
- host dependent
- interferes with cell metabolism, growth & reproduction
- latent response
- antibiotics vs anti-virals
Types of Organisms: Mycoplasms
- bacteria with no cell wall/ small size
- sensitive to some antibiotics
- very small genomes
- host dependent
Types of organisms: Bacteria
- single-cell microorganism with cell wall
- demonstrates independent growth from host
Types of organisms: Rickettsiae
- Primarily animal host
- transmitted to humans via bite from insect vector
- host dependent
Types of Organisms: Chlamydiae
- host dependent
- DNA and RNA
- susceptible to antibiotics
Types of Organisms: Prions
- composed of proteins
- redirects folding of proteins in CNS
- transmitted animal –> human
- usually long, latent period in host
- rapidly progressive when active
- mad cow disease
Pathogen
- any microorganism that may cause disease
- viruses, mycoplasms, bacteria, rickettsiae, chlamydiae, protozoa, fungi, prions, roundworms
- principal pathogens
- opportunist pathogens
- pathogenicity-ability to induce disease
- virulence-quantitative measure of pathogenicity
- ***# people who die of disease/ #people who have disease
Reservoir
- environment for organism to live & reproduce
- Human, animal, plant, soil, food, water, equipment, &/or organic substance
- Possibly more than one at different growth stages
- carriers can provide environment for parasite and shed w/o showing S/S of disease
portal of exit
- the site of leaving reservoir
- Commonly secretions, fluids, excretions, open wounds, exudates
- possibly more than one portal
Mode of transmission
- infectious organism–> susceptible host
- may travel by more than one route
1. contact : direct or indirect
2. airborne: <5 microns in size
3. Droplet: >5 microns falling within 3ft of source
4. : vehicle: common source
5. Vector: intermediary reservoir and host
Portal of entry
- site where organism enters host
- GI tract
- respiratory tract
- mucous membranes
- genitourinary tract
- skin
- trans placental
Susceptible Host
- has characteristics and behaviors that incr probability of infectious disease
- general health
- age, sex, ethnicity, heredity
- existing disease processes
- environment
- behaviors
- anything that compromises body defense/integrity
- risk of starting an infection in host varies also to number of organisms and duration of exposure
First Line of Defense
-external protection- goal is to remove organism before it multiplies
- intact skin/ mucous membranes
- oil &perspiration on skin
- flushing of secretions
- cilia in respiratory tract
- Gag/cough reflexes
second line of defense
- inflammatory process
- local response to cell injury/prevention of further invasion. Walling off invader leading to destruction
-facilitate internal defenses: Lymphatic system, leukocytes, chemicals, proteins, enzymes to trigger defenses
third line of defense
- immune response
- shares action with inflammatory response
- specific to invading organism’s antigenic character
Control Transmission: Goal
-to break chain of transmission for particular pathogen at link where most people can be protected
Control Transmission: Methods
- use of barriers, isolation, immunizations, drugs, proper nutrition, incr sanitation, address environmental factors
Isolation & Barriers
Center for disease control and the hospital infection control Practices advisory committee developed the CSC Guidelines for Isolation Precautions in hospitals
- two-tiered approach
- – standard precautions
- –transmission-based precautions: contact, airborne, droplet
Standard Precautions
-Based on the premise that every person is infected with an organism that could be transmitted in any healthcare environment
transmission based precautions
- For the care of patients known or suspected to be infected or colonized with infectious pathogens
- in addition to standard precautions to control transmission
- may be based initially on patient symptoms aand then modified once diagnosis is confirmed or ruled out
- three categories: contact, droplet, airborne
- may be combined for diseases that have multiple transmission routes
Clostridium difficile (C diff)
- anaerobic, spore-forming bacillus
- Spores can survive for months
- primarily fecal - oral route
- a leading cause of nosocomial infections
- manifests as diarrhea, but can lead to fatal inflammation of colon
- contact isolation
risk group for C diff
- antibiotic user
- > 65 yo
- residing in room which housed C diff pt 10-14 days prior
treatment of C diff
flagyl, vancomycin, probiotics
Staphylococcal Infections
- Bateria that normally resides on skin
- A leading cause of nosocomial and community acquired infections
- direct contact transmission-not easily removed by scrubbing
- most common location for colonization is nares
- hand washing/education
- manifests as local abscess filled with pus and bacteria.
- may lead to infection anywhere via bloodstream
staphyloccal infections risk group
-surgical/ burn pts, IDDM, neutropenic, prosthetics, chronic skin disease, RA, catheter, corticosteroid Rx
staphylococcal infections Pathogenesis
- usually by traumatic inoculation
- once invades, secretes membrane-damaging enzymes and toxins
Staphylococcal infections clinical manifestations
-fever, chills, pain, swelling over affected area, cellulitis
staphylococcal infections treatment
-find antibiotic to fight strain (MRSA-vancomycin)
Streptococcal Infections- Group A
- Group A streptococci (GAS)
- usually transmitted via contact with respiratory droplets
- S/S of GAS are dependent upon the location of infection
streptococcal Pharyngitis
- AKA strep throat
- incubation 1-5 days
- possible presentation: fever, sore throat, beefy red pharynx, swollen tonsils and lymph nodes, malaise, abdominal pain
- post-strep secondary conditions include Rheumatic fever or acute glomerulonephritis
streptococcal Pharyngitis treatment
antibiotics to avoid post strep syndromes
Scarlet Fever (GAS)
- usually follows untreated strep throat or wound infections
- strep strain releases pyogenic exotoxin
- common in 2-10 y/o
- transmitted by inhalation or direct contact with oral secretions
scarlet fever clinical manifestation
Fever
Sore throat
strawberry tongue
rash-sandpaper chest–> extremities
streptococcal cellulitis
- inflammation of skin and subcutaneous tissues.
- usually at wound site, but entry site not always noted
- may recur extremities with impaired lymph drainage
- lymphangitis presents with red linear streaks from affected area toward tender, swollen lymph nodes
Steptococcal Necrotizing Fasciitis (NF)
- serious,rapidly progressive infection along fascial planes. hupotension, nausea, vomiting, delirium
- type I-polymicrobial infection; p/o complication
- type II- distal break in skin or transient bacteremia
- initially, pain and fever present while skin looks unhealthy
- infection rapidly spreads –> edema and tenderness
- thrombosis of blood vessels –> dark red and indurated
- ultimately, skin becomes ischemic
treatment of NF
aggressive debridement with IV antibiotics
-culture and gram staining essential to determine antibiotics choice.
may need serial debridement
streptococcus Pneumoniae
- cause of pneumonia, sepsis, otitis media, meningitis
- transmission via direct contact or inhalation of respiratory secretions
- most common cause of community-acquired pneumonia
- most common cause of death by preventable bacterial disease by vaccination
- vaccination recommended for >65 y.o. individuals with chronic diseases or compromised immunity.
streptococcus pneumonia clinical manifestations
- present with fever, pleuritis with pain, dyspnea, productive cough, purulent sputum, elderly with delirium, slight cough
Gas Gangrene
- rare, painful; caused by anaerobic bacteria
- muscles and subcutaneous tissues fill with gas and exudate
- follows trauma or surgery
- spreads rapidly and death ca follow within hours
- growth uncommon in healthy human tissue unless devitalized tissue with severe trauma present
- usually found in deep wounds
- CO2 and H gases produced subcutaneously
signs of gangrene
clinical manifestations
- cool skin, pallor/ cyanosis; sudden severe pain, sudden edema, loss of extremity pulses
- skin darkens- cutaneous necrosis and hemorrhage
- thick discharge with foul odor
- crepitation upon palpation of skin from gas bubbles
- prevention is key to avoid gangrene by cleaning wound
- surgical debridement and antibiotics
Pseudomonas
- causes pneumonia, wound infections, UTIs, sepsis
- thrives on moist environmental surfaces
- antibiotic resistant
- aggressive growth often leading to sepsis in population with decr immunity
- contact transmission: proper hand hygiene, proper cleaning of equipment, strict sterile techniques with wounds
Blooodborne Viral Pathogens
- hepatitis B, C, HIV
- bloodborne pathogens standard
- CDC Guidelines for infected HCWs treating patients
Bloodborne pathogen standard
- by occupational safety and health administration
- to minimize exposure to HBV, HCV, HIV & other bloodborne pathogens
- use of standard precautions to decr contact with potentially contaminated body fluids
CDC Guidelines for infected HCWs treating patients
- based on assumption that risk of transmission is greates when performing invasive procedures
- avoidance of such procedures unless guided by expert panel on performance safety
- must notify pt regarding infected status before performing invasive procedure
Hepatitis B Virus
- serious risk to HCWs
- incr risk dependent upon: exposure to blood-degree of exposure, presence to HBV e antigen and hepatitis surface antigen
-transmitted via percutaneous injury or direct/indirect contact with infected blood and body fluids
- HBV in blood survives up to one week on environmental surfaces
- incubation period 45-180 days
OSHA bloodborne pathogen standard mandates
- HBV vaccine and immunoglobulin
- strict adherence to hand ashing and standard precautions
- use of barriers
Hepatitis C
- highest mode of transmission to HCWs via percutaneous injuries
- incubation period 6-7 weeks
- nearly infected will develop chronic HCV
- no vaccine available
- best route is prevention
HIV
-nosocomial transmission from pt-> HCW via percutaneous or mucocutaneous exposure to blood/body fluids
-seroconversion after percutaneous exposure to infected blood depends on:
—visible blood on device prior to injury, involves needle placement into vein or artery, deep injury with contaminated device
CDC recommends if HCW exposed to HIV:
- Counseled
- offered HIV baseline & follow-up blood testing ASAP
- treated with antiviral therapy per protocol
HIV postexposure
- contact area immediately washed with antiseptic soap and rinsed
- anti-retrovirals for four weeks
Prevention HIV
Hand washing, standard precautions, barriers
Herpesvirus
-eight types of herpeviruses
-usually subclinical primary infection vs symptomatic presentations
-may exist in latent state for life of host
-reactivation in compromised host
—widespread lesions in affected organs or CNS, severe illness in infants or immunocompromised, death
Herpes Simplex Virus type 1 (HSV-1)
- usually manifests as vesicles/sores in mouth and oral cavity
- also infects genitourinary system
- systemic symptoms-fever , malaise, myalgias
- symptoms and lesions resolve 3-14 days
- herpectic whitlow-infection of finger
- some association with Bell’s palsy
Herpes simplex virus type 2 (HSV-2)
- principal cause of genital herpes via sexual contact
- ulcers may also affect cervix, buttocks, rectum, urethra, and bladder
- painful, small, grouped lesions with itching
- sores usually heal in 1-3 weeks
- women with genital hepes may pass virus to infant during birth
HSV-1 and HSV-2
- infect and visceral organ or mucocutaneous site
- asymptomatic shedding usually immediately prior to sores appearing
- transmission via contact through break in mucous membranes/skin particularyly if host is immunosuppressed
- initial infection may be asymptomatic
- virus typically remains latent with periodic reactivation
- during primary infection, virus travels along axons of peripheral sensory nerves to nerve ganglia in CNS
- Recurrences usually milder
- may also cause meningitis, encephalitis
- no available vaccines
- diagnosis confirmed with cultures
HSV-1 and HSV-2 treatment
Anti-virals, education
HSV-1 and HSV-2 prevention
-hand washing, standard precautions, barriers
Varicella Zoster Virus
Aka herpesvirus type 3
- responsible for chicken pox/ shingles
- most common complication is secondary bacterial skin infection
- vesicles filled with high titers of infectious virus
- airborne and contact transmission
Varicella/chicken pox
- virus is present in WBCs up to five days before rash
- contagious one-two days prior to rash -> all lesions crusted
- successive lesions continue to appear for several days
- fever and malasie may precede rash
- rash wwith “dewdrop ona rose petaal”
- first appearance on scalp, then trunk, then extremities
- c/o pain and itching
- risk during pregnancy
Varicella/chicken treatment
- bed rest till afebrile; skin kept clean, itching creams or oral antihistamines
- antivirals for adults and children with high risk for complications
Herpes Zoster / shingles
- presents as unilateral lesions erupting along dermatome
- typically >50 yo or immunocompromised
- contagious to those who have not had chicken pox or vaccination
- complication is prostherpetic neuralgia
- vaccine has been approved for adults >60 y/o
Infectious mononucleosis
- caused by herpes type 4 virus aka epstein barr virus
- typically affects young adults and children
- transmission mainly via oral secretions, lesss likely through blood
- contagious before symptoms appear—> no fever and no lesions in mouth
- serious complication are rare but include Guillain-barre syndrome and ruptured spleen
- reactivation of virus may occur
Infectious mononucleosis symptoms
- fever, sore thorat, swollen cervical lymph nodes, malasie, left upper abdominal pain frm splenomegaly or heptomegaly
- treatment of restt and supportive care
Influenza virus
- caused by influenza virus A or B
- can cause serious illness, even death
- transmission person -> person via inhalation or direct contact
- secondary bacterial pneumonia could develop
- vaccination is recommended for >6 mos y/o
Influenza S/S:
Abrupt onset with high fever, malaise, myalgia, HA, dore throat, nasal congestion, nonproductive cough, nausea, vomiting, otitis media
Influenza treatment
Antivirals given within 48 hours of onset
Supportive therapy
Droplet precautions
Prevention
Respiratory syncytial virus
- serious disease for infants and elderly, esp with lung/hear existing conditions & immunocompromised
- recurrences = mild upper respiratory tract infections
- droplet precautions
respiratory syncytial virus S/S
low-grade fever, tachypnea, wheezing
respiratory syncytial virus treatment
Hydration, humidifier, supportive therapy
no vaccine available
prevention
Lyme disease
- US most prevalent vector-borne infectious disease
- caused by spirochete
- tick larvae contact bacteria from infected rodents
- bacteria can disseminate through blood stream or lymphatic system
lyme disease S/S
- erythema migrans
- fever/chills
- joint muscle pain
- HA
- fatigue
- swollen lymph nodes
Lyme disease stage 1
early , localized stage
-erythema migrans
Lyme disease stage 2
Disseminated infection
- nervous system, heart, joints
Lyme disease stage 3
Late , persistent infection
-intermittent arthritis, chronic neurological symptoms
Lyme disease post infection syndromes
-Resembles fibromyalgia or chronic fatigue syndrome-debatable
sexually transmitted disease
- caused by bacteria, viruses, and parasites
- chlamydia most reportable STD in US
- contact precautions and hand washing while working with patients
STD risk factors
- multiple sex partners
- history of blood transfusion
- failure to use condom during sexual intercourse
- sharing needles
four most common types of infections
- skin/soft tissue- MRSA
- endovascular- endocarditis, sepsis, abscess
- respiratory - pneumonia, lung abscess
- musculoskeletal- osteomyelitis, septic arthritis
