Transcript Nrsg 407 Infectious Disease

Nrsg 407 Infectious
Disease
Chp 4
Viral Infections
• Acute or Chronic
• Respiratory Tract Viruses:
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Rhinoviruses-numerous types.
Causes most cases of the
common cold
Adenovirus-Upper respiratory
track infections, causing
tonsillitis
Respiratory syncytial viruslower respiratory tract. Most
common causes of
pneumonia and bronchiolitis
in children
Influenza: Type A & B. Type
B less common, more mild.
Type A causes severe
respiratory infection
• GI:
• Rotavirus- most common
causes of diarrhea in infants
and young children.
Transmission fecal-oral
• Norovirus-usually affects
older children and adults.
Transmission due to fecally
contaminated food or water,
person-to-person, and by
aerosolization. Supportive
treatment, virus is selflimiting
Latent Virus
Infections
• Virus persists in noninfectious form
• Can periodically reactivate, resulting in new infections
• Herpes simplex virus
• Herpes zoster virus/varicella-zoster virus
• Cytomegalovirus
• HIV (refer to chapter 3)
Productive & Transformative
Virus Infections
Productive:
• Virus persists in infectious
form
• Chronic infection
• Hepatitis B & C
• Transformative: stimulates
transformation of normal
tissue into a neoplasm
• Epstein-Barr virus: infectious
mononucleosis, Linked with
some non-Hodgkin
lymphomas
• Human papilloma virus: skin
& squamous mucosa, may
cause warts, cervical cancer
• Kaposi sarcoma associated
herpes: malignant skin tumor,
most common AIDS defining
neoplasm
Bacterial Infections
Gram Positive Bacilli
Gram Positive Coccci
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Staphylococci: acute pyogenic infections
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Diphtheria: acute pharyngeal/skin infection
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Listeria Monocytogenes: causes food borne
infections through refrigerated food.
Listeriosis features bacteremia, meningitis,
encephalitis, and dermatitis
Streptococci: grouped according to antigenic
properties
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Bacillus Anthracis: agent of anthrax
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Nocardia: found in soil. Nocardiosisacute/chronic occurs in immunodeficient
patients
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Clostridia: includes:
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S. aureus causes skin abscesses, pharyngitis, bone
infection, pneumonia, & heart valve infections
Spread direct contact with kin or clothing, nostrils
Antibiotic resistant strains-MRSA
Coagulase negative staph: common cause of
endocarditis in IV drug users
Can invade bloodstream & cause secondary
infections (septicemia, endocarditis, meningitis)
May also stimulate autoimmune responses in kidney
Spread by direct contact
Alpha hemolytic: S. pneumoniae
Beta hemolytic:
• Group A: infection of pharynx or skin (cellulitis)
• Group B: neonatal pneumonia, meningitis, and
sepsis. Adults-UTI
• Group D: anaerobic, common in intestines
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C. diff-commensal anaerobe usually resides in
colon. When oral antibiotics kill off
competition, it overgrows, releases toxins &
causes pseudomembranous colitis
C. perfringens-agent of gas gangrene
C. tetani-agent of tetanus (acute poisoning
from a neurotoxin
Gram Negative Cocci
• N. meningitidis (meningococcus)
• Cause of meningitis in young children
• Spread by respiratory droplets
• Epidemics occur in underdeveloped nations
• Meningococcal meningitis
• Life threatening emergency
• Diagnosis confirmed with spinal fluid & blood culture
• When individuals encounter subtypes not immune to
• Day care, college, military
Lyme Disease
• Spirochete Borrelia burgdorferi
• Spread from rodents to humans by bite of deer tick
• Three stages of disease development
• Stage 1: red skin lesion with pale center, mild fever and
lymphadenopathy
• Stage 2: lymphadenopathy, recurrent fever, skin rash, joint
& muscle pains, cardiac arrhythmias, and meningitis
• Stage 3: chronic disease, 2-3 years after bite
Mycobacteria
• Mycobacterium tuberculosis-TB
• Mycobacterium leprae-leprosy
• Mycobacterium avium-infects birds & humans
• Mycobacterium bovinum-infects cattle & humans
TB Diagnosis &
Treatment
• Primary infection asymptomatic
• Except when initial infection overwhelms defenses (pts.
With AIDS)
• Subtle onset S/S: low fever, night sweats, weight loss,
poor appetite
• Pulmonary s/s begin later
• Mantoux test: (PPD) skin test for infection
Fungus Infections
• Fungi-nucleated cells with a cell wall
• Grow in two forms: multicellular filaments (molds) or
sing cells (yeast)
• Fungus is a mycosis
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Superficial mycoses-skin, hair, nails (most common)
Subcutaneous: skin, subcutaneous tissues & lymphatics
Endemic: serious systemic disease in health people
Opportunistic: fatal systemic disease in
immunosuppressed, or where indwelling
catheters/medical hardware is present
Candida
• Skin, mouth, GI, & vagina
• C. albicans most common
• Infection occurs when normal flora breach skin or
mucosal barriers
• May spread systemically especially in patients with low
neutrophil count
• Most common: diaper rash & vaginitis
Parasite Infections
• Parasite is an organism living in another organism &
benefits by deriving nutrients for itself at the expense
of the host
• Three types: Protozoa, Worms, & Ectoparasites
Protozoa
• Larger & more complex than bacteria and fungi
• Causes:
• Malaria-small plasmodium amoebae
• Amebiasis-food contaminated with human feces that contains
amebic cysts
• Leishmaniasis: chronic inflammation of skin, mucous
membranes, & viscera caused by Leishmania. Transmitted
from infected animals by sandflies
• Trypanosomiasis: microscopic protozoa that infect blood.
Transmitted from human to human by insects. Includes
sleeping sickness
• Giardiasis: acute/chronic diarrhea. Transmitted by ingesting
fecally contaminated water or unwashed vegetables/fruits
Worms
• Helminths-worms vary in length and migrate from point of entry
through various organs. Diagnosis is by detection of worm/eggs
by biopsy or stool examination
• Roundworms: infect intestines or subcutaneous tissues
• Intestinal roundowroms: live in intestine, spread by oral-fecal
contamination
• Hookworms: intestinal roundworms enter through skin & infect
blood
• Pinworm: common pediatric infection. Transmitted oral-fecal
route
• Trichinosis: transmitted by eating inadequately cooked infected
pork
Flatworms
• Infect blood vessels, GI, lungs, and liver
• Schistosomiasis: most important of ALL worm
infections
• Eggs passed in urine and stool into water where larvae
infect snails and mature before reentering water to invade
skin of humans and spread through the blood
Ectoparasites
• Live on Skin or Hair
• Lice: wingless, blood-sucking insects that infest the hair
of the head, body, or pubis
• Scabies: infestation of the skin mite Sarcoptes scabiei.
Lives only in skin of humans. Transmitted through direct
contact.
Sexually Transmitted
Infections (STI)
• Infection transmitted by sexual contact
• Any organism can cause STIs
• Viral, bacterial, and parasitic
• Important facts:
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Immunity not often achieved, reinfection is possible
Diagnostic testing not easily obtainable
Cases treated syndromically, lacking a definitive diagnosis
Infection often asymptomatic (especially in women)
More than one STI may be present
Patient follow-up or contagion tracing often unavailable
No cure for viral STIs (HPV, HIV/AIDS, genital herpes)
Laboratory Tools
• Microbial culture
• Gold standard