General Pathology 300 (Infections, cont.) Flashcards
mycobacterial infections
..
what are mycobacteria
Mycobacteria are small, slow-growing aerobic bacteria
what are mycobacteria distinguished by
distinguished by a complex, lipid-rich cell envelope
what are TWO examples of diseases caused by mycobacteria
Diseases caused by mycobacteria include TUBERCULOSIS and LEPROSY.
mycobacteria etymology
myco = “mushroom, fungus,”
Tuberculosis
An infectious, inflammatory systemic disease that affects the lungs
TB, dissemination
may disseminate to involve lymph nodes and other organs.
Tuberculosis, (PATHOGEN?)
Caused by Mycobacterium tuberculosis
tuberculosis, TRANSMISSION and MODE OF ENTRY
Infection most commonly occurs through INHALED DROPLETS
TB, pathogenesis
Once a susceptible person inhales an infected droplet, the bacteria become established in the lungs
and a proliferation of epithelial cells surrounds and encapsulates the multiplying organisms in an attempt to wall them off.
TB, pathogenesis 2
The granulomas eventually become necrotic in the center leading to fibrosis and calcification of tissues.
In later stages of the disease, the bacteria is able to enter the blood and lymph circulation and ultimately colonize distant sites.
granuloma
A granuloma is a tiny cluster of white blood cells and other tissue.
It can appear in your lungs, skin or other parts of your body.
Granulomas aren’t cancerous.
They form as a reaction to infections, inflammation, irritants or foreign objects.
TB mortality
TB kills 3 million people per year (worldwide)
which infectious disease causes the most deaths?
TB
Leading infectious disease cause of death
Represents 1/3 of world’s preventable deaths
TB, SSx
Fever
Night-time sweating
Loss of weight
Persistent cough
Constant tiredness
Loss of appetite
why loss of appetite during infection?
“When you are seriously ill, your body may not be able to use food to build itself up. Because the body recognises that it can no longer use as much food as before, your appetite becomes smaller.”
TB, Dx
culture sputum;
tuberculin skin test
tuberculin define
a sterile protein extract from cultures of tubercle bacillus, used in a test by hypodermic injection for infection with or immunity to tuberculosis, and also formerly in the treatment of the disease.
tuberculin skin test
The test is done by putting a small amount of TB protein (antigens) under the top layer of skin on your inner forearm.
If you have ever been exposed to the TB bacteria (Mycobacterium tuberculosis), your skin will react to the antigens by developing a firm red bump at the site within 2 or 3 days.
sputum culture
You will be asked to cough deeply and spit any phlegm that comes up from your lungs into a special container.
The sample is sent to a lab. There, part of it is placed in a special dish (culture). It is then watched for two to three days or longer to see if bacteria or other disease-causing germs grow.
TB, tx
antibiotic cocktail
TB, prevention
vaccination
VIRAL INFECITONS
Viruses are the smallest microorganismS.
They are always pathogens.
They depend completely on cells to reproduce. (OBLIGATE PATHOGENS)
For infection to occur, the virus first attaches to the host cell.
virus, structure
They have an outer cover of protein, and sometimes lipid, and an RNA or DNA core.
what does the virus DNA/RNA do when it finds host cell?
The viral DNA or RNA then separates from the outer cover (uncoating) and replicates inside the host cell in a process that requires specific enzymes.
what happens to the host cell after it is affected by the virus DNA/RNA?
The host cell typically dies, releasing new viruses that infect other host cells.
viral infections, E.g.
Rubella – caused by rubella virus
AIDS – caused by HIV
Flu – caused by influenza virus
Cold – caused by rhinovirus
Pneumonia
Measles
Hepatitis
Herpesvirus
Family of DNA viruses that cause active or latent infections
herpes virus types
Herpes simplex 1 (HSV-1)
Herpes simplex 2 (HSV-2)
Varicella-zoster virus (VZV)
Epstein-Barr virus (EBV)
Cytomegalovirus (CMV)
Herpes Simplex
Causes oral herpes – cold sores (most common)
—> usually via HSV1
Causes genital herpes (second most common)
—> usually via HSV2
Easily transmitted via direct contact, but can also be transmitted via indirect contact
indirect contact?
(objects with viruses on surface, surviving for variable periods depending on environment and depening on virus)
(?)
HSV1 vs 2 (mouth vs genitals?)
note that HSV1 can still affect genitals, and HSV2 can still affect mouth
HSV1 vs 2 severity
HSV1:
“substantially less severe both in terms of recurrences and shedding”
HSV transmission
Can be transmitted through contact with lesion or with contact of bodily fluids
Can also be transmitted during asymptomatic periods (asymptomatic viral shedding)
how can HSV be transmitted from mother to child?
Can be transmitted from mother to child via birth canal
(during birth)
(?)
HSV symptomatic vs asymptomatic phase
Symptomatic phase includes sores on face, mouth, genitals, hands
Symptomatic phase alternates with periods of remission
Virus tends to burn out over time
No treatment or vaccine
HSV, treating symptoms – and prevention
Symptoms -antiviral meds
Prevention - condoms
Varicella-Zoster Virus
Causes chicken pox
Can persist in peripheral nervous system as latent infection
Reactivated as shingles in adults
chicken pox characteristics
Chicken pox characterized by small, itchy vesicles all over body
chicken pox, children vs adults
In children, usually benign self-limiting disease
Chicken pox in adults generally more painful, more scarring
VZV, complications
Can develop into life threatening ENCEPHALITIS or pneumonia
VZV, immunity after infection
Infection generally confers life long immunity
VZV, prevention
Prevention – vaccination
Shingles
Shingles aka herpes zoster
Characterized by UNILATERAL painful blisters
shingles, treatment (SSx)
Treatment – antiviral meds, painkillers
shingles, prognosis
Prognosis – usually self-limiting within 5 weeks
EBV
Epstein-Barr virus
Cause infectious mononucleosis (“mono” or the “kissing disease”)
EBV/mono, characteristic SSx
Characterized by fatigue, malaise, sore throat
Mild except for in Immunocompromised people, elderly, newborns
CMV
Cytomegalovirus
Very common
Causes symptoms similar to IM
CMV and TORCH (exogenous (microbial) teratogens)
Can cause congenital defects in developing embryo if maternal infection (TORCH)
Enterovirus
Members of the PICORNAVIRUS family (small RNA viruses)
Affects millions of people per year
Symptoms can range from mild to severe
picornavirus
any of a group of very small RNA viruses which includes enteroviruses, rhinoviruses, and the virus of foot-and-mouth disease.
picornavirus etymology
pico
RNA
virus
The name “picornavirus” has a dual etymology.
The name derives from picorna- which is an acronym for “poliovirus, insensitivity to ether, coxsackievirus, orphan virus, rhinovirus, and ribonucleic acid”
Secondly, the name derives from pico-, which designates a very small unit of measurement (equivalent to 10−12), combined with rna to describe this group of very small RNA viruses.[8]
enterovirus, viral shedding (?)
Shed in oral secretions, stool, blood, CSF, nasal secretions
enterovirus, conditions/diseases
aseptic meningitis,
acute paralysis,
hand, foot and mouth disease,
myocarditis,
mild respiratory illness,
conjunctivitis
and polio (?)
entervirus, pathogenesis
Enters the mouth via the fecal-oral route, multiplies in tissues, reaches the CNS
Example includes polio
poliovirus
(part of larger category of enteroviruses, which is part of larger category of Picornaviruses)
Enterovirus, a genus within the family Picornaviridae, comprises enteroviruses, coxsackieviruses, rhinoviruses, polioviruses, and echoviruses.
E.g. Poliovirus
Causes poliomyelitis (“polio”)
Highly contagious via fecal-oral route or direct contact
Symptoms can range from mild/asymptomatic to severe paralysis in children
Routine vaccination (1950s)
(note Iron Lung)
Influenza Virus
Causes an acute febrile upper respiratory infection; “the flu”.
Highly contagious airborne disease
Incubation period of 1 – 4 days
—> Can be contagagious 5 -10 days after symptoms start
febrile
having or showing the symptoms of a fever.
“a febrile illness”
incubation period
the period between exposure to an infection and the appearance of the first symptoms.
“hepatitis B has an incubation period of 30 to 180 days”
influenza, symptoms
Symptoms include fever, cough, headache, nasal discharge and malaise.
Can range from mild symptoms to respiratory failure/death
which patients are at risk for severe symptoms & mortality during influenza infection?
Mortality is common in high risk patients.
—> Elderly, infants, immunocomprimised
influenza virus, Tx
Antivirals
Prevention
-> Vaccine
—> Has 2 strains of Influenza A and 1 strain of Influenza B
influenza virus structure
Single stranded RNA virus.
3 types of influenza virus
3 types of influenza virus
—> Types A, B, and C
which type of influenza is most often responsible for human infection?
Type A is responsible for most human infections.
4th type of influenza virus (???) —> (Not on notes)
Influenza D viruses primarily affect cattle with spillover to other animals but are not known to infect people to cause illness.
how are influenza types identified?
Identification can be from surface proteins (Type A)
—> Hemaglutinin and Neuraminidase proteins
—-> Example: H1N1, H5N1
which influenza virus type has very high mutation rate?
Influenza A has a very high mutation rate
—> Approx 300x higher than other microbes.
—> Occurs via antigenic drift and antigenic shift
antigenic drift
takes longer to occur
small mutations over time
minor structural changes
antigenic shift
occurs in shorter period of time compared to drift
combination of viruses producing new sub-type
larger structural changes
shift, define 2
“Antigenic shift is the process by which two or more different strains of a virus, or strains of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains”
example of antigenic shift
flu of bird and flu of human infect pig, and viruses combine to create new strain (ANTIGENIC SHIFT)
“If a pig catches both a human influenza A virus and an avian influenza A virus at the same time, it can spark a process known as viral reassortment — a genetic exchange in which flu viruses swap gene segments.”
Rhinovirus
RNA virus
Causes upper respiratory tract infection (URTI)
Most common cause of the “common cold”
rhinovirus, URTI, common cold – features, SSx
Acute, afebrile, mild, self-limiting infection
Symptoms include rhinorrhea, sneezing, nasal obstruction and coughing.
rhinovirus, transmission, mode of entry
Transmission is usually by direct contact or aerosol particles
Fungal infections
Mycosis - any disease induced by a fungus
Fungi include yeasts and molds
are fungi generally pathogenic in healthy individuals?
Many fungi are opportunists and are not usually pathogenic except in a compromised host.
superficial fungal infections
Superficial – limited to outermost layers of skin and hair
systemic fungal infections
Systemic - affect severely immunocompromised patients
Often have acute presentations with rapidly progressive pneumonia, fungemia, etc.
pneumonia
Pneumonia is an infection of one or both of the lungs caused by bacteria, viruses, or fungi.
fungemia
Fungemia is the presence of fungi or yeast in the blood.
The most common type, also known as candidemia, candedemia, or systemic candidiasis, is caused by Candida species.
Candidemia is also among the most common bloodstream infections of any kind.
FUNGAL PNEUMONIA, pathogen
mortality (?)
Caused by…
Pneumocystis carinii / pneumocystis jirovecii
Extremely serious form of pneumonia
Causes significant mortality in IMMUNOCOMPRIMISED patients
carinii and jirovecii etymology
carinii:
proposed the species name P. carinii in honor of Antonio Carini
jirovecii:
named in honor of Czech parasitologist Otto Jirovec
YEAST INFECTION
via Candida albicans
Normally populates GI tract, mouth, genitals
Overgrowth causes candidiasis (genitals) or thrush (mouth)
Candida albicans
Candida albicans is a naturally occurring fungus that lives on your body
candidiasis
infection with candida, especially as causing oral or vaginal thrush.
“Candidiasis is an opportunistic infection due to Candida, which can affect the oral cavity, vagina, penis, or other parts of the body.”
“Untreated Candida infection carries the risk of leading to a systemic infection in which other organs can become involved and may lead to sepsis.”
thrush
infection of the mouth and throat by a yeastlike fungus, causing whitish patches.
“a disease that is caused by a fungus (Candida albicans), occurs especially in infants and children, and is marked by white patches in the oral cavity.”
“Another name for thrush in your mouth or throat is oropharyngeal candidiasis.”
candidiasis and thrush
“candidiasis (genitals) or thrush (mouth)”
note again, candidiases vs thrush
Candidiasis (sometimes called moniliasis or a yeast infection) is an infection caused by yeast on the skin and mucous membranes.
When the infection occurs in the mouth, it is called thrush.
Sexually transmitted infections (most common)
Herpes
Warts
Chlamydia
Gonorrhea
Hepatitis
Syphilis
Genital Warts
Human Papilloma Virus
More than 100 different types of HPV
—> Approx 35 have an affinity for genitals
WHICH CANCERS IS HPV INFECTION LINKED TO ?
linked to a higher incidence of CERVICAL, ANORECTAL and BLADDER cancers
genital warts, incidence
Incidence: 5.5 million new cases/yr;
incidence rapidly escalating
genital warts, transmission
unprotected sexual contact
Infection of newborn through delivery
where do warts appear (around genitals), and after how long (?)
Warts on genitals, anal region, cervix etc.
1-6 months after sexual contact with infected person
genital warts, treatment
Warts can be removed using chemical, ablative or surgical therapies.
—> Recurrence is common (when removed this way?)
genital warts, if untreated
Spontaneous resolution
—> 75% after 2 years
in others there is possibility for…
—> Increase in size or numbers
—> or remain unchanged
genital warts and CERVICAL cancer in women
In women abnormal pap smear can indicate possible cervical cancer
pap smear define
a test carried out on a sample of cells from the cervix to check for abnormalities that may be indicative of cervical cancer.
why called pap smear (?)
It is named after Georgios Papanikolaou, the doctor who determined its use in detecting early signs that could lead to cervical cancer.
Chlamydia
Caused by bacteria: Chlamydia trachomatus
Incidence: 3 million new cases/yr
what is the MOST COMMON STI caused by bacteria
CHLAMYDIA
chlamydia, transmission
unprotected sexual contact
infection of newborn during delivery
—> Conjunctivitis
—> Pneumonia
Chlamydia, clinical manifestations (SSx) in MEN
Asymptomatic in 50% of cases
urethritis with discharge
Pain with urination (dysuria)
Unilateral pain and swelling of scrotum (epididymitis)
Fever
Chlamydia, clinical manifestations (SSx) in WOMEN
Asymptomatic in 80% of cases
Endocervicitis with discharge
Pain during urination (dysuria)
Abdominal/pelvic pain
Intermenstrual bleeding
Painful intercourse (dyspareunia)
Fever
dyspareunia etymology
dys – difficult, bad
pareunos – lying with
-ia suffix
“Suffix meaning condition, esp. an abnormal state, and taxonomic names of genera classes or orders.”
note also -osis:
“Osis is a suffix meaning ‘disease or condition of’”
Chlamydia, COMPLICATIONS
PELVIC INFLAMMATORY DISEASE
—> Inflammation and scarring through fallopian tubes resulting in infertility
REACTIVE ARTHRITIS (Reiter Syndrome)
—> not same as psoriatic “, and septic (infective) “
Chlamydia treatment
Treatment - antibiotics
Gonorrhea
Caused by bacteria - Neisseria gonorrhoeae
Incidence: 650,000 new cases/yr
Neisseria etymology
“Neisseria is named after Albert Ludwig Sigesmund Neisser, a German physician who discovered Neisseria gonorrhoeae in 1879.”
“Neisseria is a large genus of bacteria that colonize the mucosal surfaces of many animals. Of the 11 species that colonize humans, only two are pathogens.”
gonorrhea etymology
gonos = semen
rrhea = discharge; flow.
gonorrhea typically affects…
Typically infects lower genital tract but can infect almost any mucus membrane
gonorrhea, tranmission
Unprotected sexual contact
Infection of newborn via delivery
gonorrhea, clinical manifestations (SSx) in MEN
urethritis with discharge
increased urge to urinate
pain during urination
gonorrhea, clinical manifestations (SSx) in WOMEN
Endocervicitis with discharge
pain during urination (dysuria)
Abdominal/pelvic pain
Intermenstrual bleeding
Painful intercourse (dyspareunia)
gonorrhea, asympomatic?
Can be asymptomatic in males and females
gonorrhea, COMPLICATIONS (if untreated?)
PELVIC INFLAMMATORY DISEASE
—> Inflammation and scarring through fallopian tubes leading to infertility
DISSEMINATED GONOCOCCAL INFECTION
—> Infection moves into blood and spreads.
—> Causes widespread tenosynovitis, arthralgias and dermatitis
gonorrhea, aka
gonococcal infection
which organs can DISSEMINATED GONOCOCCAL INFECTION affect?
Causes widespread tenosynovitis, arthralgias and dermatitis
Gonococcemia (aka disseminated gonococcal infection)
“Gonococcemia is a rare complication of mucosal Neisseria gonorrhoeae infection, or Gonorrhea, that occurs when the bacteria invade the bloodstream. It is characterized by fever, tender hemorrhagic pustules on the extremities or the trunk, migratory polyarthritis, and tenosynovitis”
Gonorrhea – what can happen if it is UNTREATED?
If left untreated, it may progress to
-> septic (INFECTIVE) arthritis,
-> MENINGITIS
-> or ENDOCARDITIS.
gonorrhea, tx
Antibiotics
Prevention through safe sex practices
Hepatitis B
Caused by HBV (Hepatitis B virus)
Incidence: 77,000 new cases/yr
HBV, structure
DNA virus
Hepatitis B virus, transmission
infected blood: needles/drug use
sexual contact
delivery
horizontal vs vertical transmission
vertical = from mother to newborn/child
(perinatal tranmission)
Hepatitis B, SSx
jaundice,
arthralgias,
rash,
dark urine,
anorexia,
nausea,
painful abdominal bloating,
clay-coloured stools,
fever
hepatitis, why clay-coloured stools?
You may have clay-colored stools if you have a liver infection that reduces bile production, or if the flow of bile out of the liver is blocked.
hepatitis B, why “anorexia” ?
Because your liver plays a role in digestion, you may experience a loss of appetite, feel a little nauseous, or experience pain in the upper right quadrant of your abdomen
hepatitis B, acute infection vs chronic/asymptomatic/inactive infection
After acute infection, they may progress to an inactive/asymptomatic chronic infection
—> 5%-10% progress to an active chronic infection
Hepatitis B, Tx
Vaccination
Antiviral meds
Liver transplant
Hepatitis B, prognosis
Inactive and active chronic infection can progress to liver CIRRHOSIS, liver failure and HEPATOCELLULAR CARCINOMA.
cirrhosis
a chronic disease of the liver marked by degeneration of cells, inflammation, and fibrous thickening of tissue.
It is typically a result of alcoholism or hepatitis.
hepatocellular carcinoma define
Primary liver cancer—cancer that starts in the liver—is called hepatocellular carcinoma (HCC).
It is the sixth most-common form of cancer worldwide, but the third leading cause of death from cancer.
HCC almost always occurs in people who have had liver disease for many years.
Syphilis
STI caused by bacteria - Treponema pallidum (SPIROCHETE)
Incidence: 70,000 new cases/yr
syphilis, transmission
Transmission:
unprotected sexual contact,
contact with skin and mucous membranes,
TRANSPLACENTAL,
blood transfusions
syphilis, pathogenesis
The bacteria enter through the mucous membranes or skin, reach the lymph notes and rapidly disseminate through the body.
Primary syphilis
painless lesion (chancre) at the site of inoculation (?) 3-8 weeks after infection
Secondary syphilis
flu-like symptoms and rash 6wks to 2 years after infection
syphilis – latent period
Latent Period – Can last years to decades.
Asymptomatic and non-contagious.
Tertiary syphilis
About 1/3 of untreated individuals will develop tertiary syphilis.
Not contagious at this stage.
tertiary syphilis, classification
cardiovascular syphilis,
neurosyphilis
or gummatous syphilis
gumma
a tumor of gummy or rubbery consistency that is characteristic of the tertiary stage of syphilis
“a small soft swelling which is characteristic of the late stages of syphilis and occurs in the connective tissue of the liver, brain, testes, and heart.”
gummatous syphilis
Gummatous syphilis is a rare form of tertiary disease manifested by gummas (granulomatous nodules with a somewhat rubbery texture and necrotic centers)
that typically affect the skin and are most often found internally in the liver as well as the testes, brain, heart, and bone but can also develop in any organ.
which stages of syphilis can be cured/treated?
Primary, secondary and latent syphilis can be cured with antibiotics
which stage of syphilis can create irreversible damage?
Tertiary syphilis can occur up to 20 yrs after initial infection and may cause irreversible cardiovascular neurological damage
VACCINATION
A vaccine is any suspension containing antigenic molecules derived from a microorganism, given to stimulate an immune response to infectious disease.
Vaccines can be administered intramuscularly, subcutaneously, intradermally, orally or intranasally.
what are ways that vaccines can be made?
Vaccines may be made from weakened or killed microorganisms inactivated toxins or immunologically active surface markers extracted or copied from microorganisms.
