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93. Microbiology p194-206

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Medically important helminths
p194
Which Cestode (tapeworm) can cause brain cysts and seizures?
Taenia solium
Echinococcus granulosus (a cestode) can cause cysts in the ____when ingested in dog feces; and _____ if antigens are released from cysts
liver, anaphylaxis
What is the standard treatment for trematodes (flukes)?
Praziquantel
Which fluke penetrates human skin, forming granulomas, fibrosis, and inflammation of the spleen & liver?
Schistosoma
Larvae of the nematode (roundworm) ___ are known to penetrate skin of feet & cause anemia if infect intestine.
Ancylostoma duodenale (hookworm)
Echinococcus granulosus (a cestode) can cause cysts in the ____when ingested in dog feces; and _____ if antigens are released from cysts.
liver, anaphylaxis
Which nematode causes anal pruritis?
Enterobius vermicularis (pinworm)
Lavae of the nematode ___ are found in the soil, penetrate the skin, and cause intestinal infection.
Strongyloides stercoralis
Trichinella spiralis (a nematode) is usually found in what food?
undercooked meat, usually pork
Which nematode can be seen crawling in the conjunctiva?
Loa loa
Treatment for river blindness, caused by onchocerca volvulus, is ___
Ivermectin
Wuchereria bancrofti cause blockage of lymphatic vessels in a condition known as:
elephantiasis
Three nematodes treated with Diethylcarbamazine:
Loa loa, Toxocara canis, and Wucheria bancrofti
Parasite hints
p195
Perianal pruritis caused by:
Enterobius
Microcytic anemia a result of infection with
Ancylostoma, Necator
Schistosoma mansoni is known to result in
portal hypertension
Schistosoma haematobium can cause ___ cancer and hematuria
bladder
A trematode that causes hemoptysis is:
Paragonimus westernani
Clonorchis sinensis causes disease in the:
biliary tract
Virology
p195
All DNA viruses are dsDNA except:
parvoviridae
All DNA viruses are linear except these two:
papoviruses, hepadnavirus (circular)
All RNA viruses are ssRNA except
Reoviridae ("repeato-virus" (reovirus) is dsRNA)
Do hepadnavirus, herpesviruses, and poxvirus have an envelope?
Yes
Which virus is often responsible for "pink eye" (conjunctivitis)?
adenovirus
Which SS-linear(-) DNA virus is responsible for "slapped cheeks" rash?
Parvovirus
Which is the smallest DNA virus?
Parvovirus
Which DNA virus can cause aplastic crises in sickle cell disease?
Parvovirus (B19 virus)
Name 3 "naked" DNA virsuses (no envelope)
Parvo, Adeno, and Papovirus (you have to be naked for a PAP smearÂ…)
The largest DNA virus, one which can cause "milkmaid's blisters" or molluscum contagiosum (and could be used in germ warfare), is:
poxvirus
DNA virus characteristics
p196
Papovirus is not linear, but rather ____
circular, supercoiled
The only DNA virus that is not icosahedral is
Pox (complex)
All DNA viruses replicate in the nuclear except
Pox (carries own DNA-dependent RNA polymerase)
RNA viruses
p197
Poliovirus, Echovirus,Rhinovirus, Coxsackievirus, and HAV are all members of which viral family?
Picornaviruses ("PERCH")
Picorna-, Calci-, Flavi-, Toga-, Retro-, and Coronaviruses all share which RNA structure?
SS + linear
Which SS-linear, nonsegmented RNA virus family is responsible for measles, mumps, and croup?
PaRaMyxovirus (Parainfluenza-croups; RSV-bronchiolitis in babies; Measles, Mumps)
Hantavirus, Sanfly/Rift Valley fevers, and California encephalitis are all part of this SS-circular RNA viral family.
Bunyaviruses
Orthomyxoviruses include which ubiquitous virus?
Influenza virus
HIV and HTLV are both ____ with ____capsid symmetry.
retroviruses; icosahedral
What is the #1 cause of fatal diarrhea in children?
Rotavirus (a reovirus)
Rabies is caused by this viral family.
Rhabdoviruses
Virus family credited with the "common cold"
Coronaviruses
Ebola/Marburg hemorrhagic fever are caused by which viral family?
Filoviruses
More virology
p198
Three naked (nonenveloped) RNA viruses are:
Calcivirus, Picornavirus, Reovirus (Naked CPR)
From where to herpesviruses aquire their envelopes?
nuclear membrane
From where do enveloped viruses usually acquire their envelopes?
plasma membranes
This is the only virus that is not haploid:
retrovirus (which has 2 identical ssRNA molecules, so considered diploid)
The only DNA viruses that does not replicate in the nucleus is:
poxvirus
The two RNA viruses which do not replicate in the cytoplasm are:
Influenza virus and retroviruses
Viral Vaccines
p198
Live attenuated vaccines induce humoral and cell-mediated immunity, while killed viruses induce only ____ immunity.
humoral
Are MMR (measles, mumps, rubella) vaccines live or killed?
Live attenuated
Rabies, influenza, HAV, and Salk polio vaccines are of which type (live or killed)?
Killed (SalK=killed)
A recombinant viral vaccine exists for which virus?
HBV (antigen=HBsAg)
Worldwide pandemics of influenza virus are in part attributable to which type of viral genetics?
Reassortment (viruses with segmented genomes exchange segments)
Viral Pathogens
p199
What structural similarity is shared by herpesviruses, HBV, and smallpox virus?
They are DNA enveloped viruses.
RNA nucleocapsid enteroviruses include which pathogens?
poliovirus, coxsackievirus, echovirus, HAV
The viral pathogens adenovirus, papillomaviruses, and parvoviruses are all what type of viral pathogens?
DNA nucleocapsid viruses
Bunyaviruses, Orthomyxoviruses (influenza viruses), Arenaviruses, and Reoviruses are all what type of RNA virus?
segmented (BOAR)
Aseptic (viral) meningitis can be caused by which small RNA viruses?
poliovirus, coxsackievirus, echovirus (and not by two other picoRNAviruses, rhinovirus and HIV)
Reovirus considered the most important global cause of infantile gastroenteritis
Rotavirus (ROTA=Right Out The Anus)
All paramyxoviruses have 1 serotype with this exception:
parainfluenza virus (4 serotypes)
Parotitis can be caused by this paramyxovirus:
mumps virus ("mumps gives you bumps")
Triad of mumps symptoms are:
asceptic Meningitis, Orchitis, and Parotitis (MOP)
Measles virus
p. 200
What virus type causes measles?
paramyxovirus
What bluish-gray spots on the buccal mucosa are diagnostic of measles
Koplik spots
3 Cs of measles
Cough, Coryza, Conjunctivitis
3 possible sequellae
SSPE, encephalitis, giant cell pneumonia. SSPE = subacute sclerosing panencephalitis
Influenza viruses
p. 200
Five facts about Influenza: enveloped/nonenveloped, nuclear material, antigens, infection --> what risk?, protection.
1. Enveloped 2. ssRNA with segmented genome 3. Hemagglutinin and neuraminidase antigens 4. Risk of fatal bacterial superinfection 5. Protection = killed viral vaccine
Treatment for influenza A?
Amantadine, rimantadine, zanamivir, and oseltamivir
Treatment for influenza B?
Zanavir and oseltamivir (neuraminidase inhibitors)
Rabies virus
p. 200
Rabies -- _______ (cytoplasmic inclusion) in _______(cell type)
Negri bodies in neurons
Rabies -- incubation period
weeks to 3 months
Rabies -- most common sources in US
bat, raccoon, skunk (>dog)
Rabies travels to the CNS byÂ…
retrograde migration up nerve axons
Arboviruses
p. 200
Arbovirus -- mode of transmission
Transmitted by arthropods (mosquitoes, ticks)
Arbovirus -- classic illnesses
Dengue fever (in SE Asia = hemorrhagic shock syndrome) and yellow fever
Arbovirus -- members of the family
flavivirus, togavirus, bunyavirus
Yellow fever
p. 200
Yellow fever is transmitted by ____________
the Aedes mosquito
Symptoms of yellow fever
high fever, black vomitus, and jaundice.
Yellow fever -- histology
Liver: councilman bodies (acidophilic inclusions)
Herpesviruses
p. 201
Name the diseases caused by the following Herpesviridae:
HSV-1
respiratory secretions and saliva
HSV-2
sexual contact, perinatal
VSV
respiratory secretions
EBV
respiratory secretions, saliva
CMV
congenital, transfusion, sexual contact, saliva, urine, transplant
HHV-8
sexual contact
Name the routes of transmission for the following Herpesviridae:
Mononucleosis
p.201
Mononucleosis is caused by _______
EBV
symptoms of mono
fever, hepatosplenomegaly, pharyngitis, and lymphadenopathy (esp posterior auricular nodes)
how do you test for mono?
heterophil antibody test
what do you see in the peripheral blood (mono)?
atypical lymphocytes (cytotoxic T cells)
Tzank test
p.201
What's a Tzanck test?
A smear of an opened skin vesicle to detect multinucleated giant cells (seen in HSV-1, HSV-2, VSV)
Hepatitis transmission
p.201
Name the type of nucleic acid and the virus type for the following hepatitis viruses:
Hepatitis A
fecal-oral
Hepatitis B
parenteral, sexual, maternal-fetal
Hepatitis C
blood (IV drug users)
Hepatitis D
coinfection with HBV!
Hepatitis E
enterically; water-borne epidemics
Name the mode of transmission for the following hepatitis viruses
which Hepatitis virus causes a high mortality rate in pregnant women?
E
which hepatitis virus has a short incubation period?
A (3 weeks)
which Hep virus has a long incubation period?
B (3 months)
which Hep virus has a DNA-dependent DNA polymerase?
B; reverse transcription also occurs
which pairs of viruses are similar in course, severity, and incubation?
HAV & HEV; HBV & HCV
Which virus type infection leads to chronic-carrier-status?
B, C, and D
Hepatitis serologic markers
p. 202
If I got a Hepatitis B vaccine (no infection), for what Ab would I have a positive serology?
HBsAb
If I recently had a Hepatitis B infection, for what Ab would I have a positive serology
HBsAb and HBcAb (positive during window period)
What test tells you either that I have a current infection or that I am a chronic Hep B carrier?
HBsAg
What test demands that you(the doctor) to tell me to stop having sex with my spouse lest I give them Hep B?
HBeAg
What test tells you(the doctor) that I can resume sex with my spouse because I'm not likely to give them Hep B?
HBeAb (indicates low transmissibility)
What is the "window period"?
after the actue infection is cleared and before the humoral response produces lots and lots of Ab (HBsAg AND anti-HBs negative; HBcAb positive)
How big is the Hep B virus
42 nm
When can I detect HBV particles by DNA polymerase?
during the incubation period and the acute disease period
How can I distniguish between complete recovery from Hep B infection and the chronic carrier state?
Complete recovery: HBsAg-neg, HBsAb-pos; Chronic carrier: HBsAb-neg. HBsAb-pos; HBcAb is positive in BOTH states
HIV
p. 203
HIV has a ________ genome with __<#>__ molecules of __<nucleic acid>____
HIV has a diploid genome with 2 molecules of RNA
HIV: name the "rectangular nucleocapsid protein"
p24
HIV: name the envelope proteins
gp41 and gp120
HIV: name the matrix protein
p17
HIV: what other important protein hangs out inside the nucleocapsid?
reverse transcriptase
Does HIV integrate into the host genome?
YES. HIV syntehsizes dsDNA from RNA and integrates the dsDNA into the host genome
HIV diagnosis
p. 203
How do I make a diagnosis of HIV?
ELISA --> confirmed by Western blot
T or F: HIV testing is always positive 1-2 weeks after infection
FALSE. ELISA/Western blot look for viral PROTEINS and can be falsely negative for the first 1-2 months of HIV infection
How can I monitor the effect of HIV drug therapy?
HIV PCR/viral load
HIV immunity
p. 203
Who is immune to HIV?
homozygous for CCR5 mutation
What % of US caucasians have a slower course of HIV infection because of heterozygosity for the above allele?
20%
Persons with ______________ have a rapid progression to AIDS
CXCR1 mutation
Time course of HIV infection
p. 203
HIV become symptomatic _____ after infection
3-10 years
Anti-p24 and anti-gp120 increase between _______ after initial infection; after the onset of immunodeficiency, they ___________(increase or decrease)
1-2 months; decrease
Opportunistic infections in AIDS
p. 204
Name the opportunistic infections seen in the following categories: (for AIDS patients)
bacterial
TB, Mycobacterium avium-intercellulare complex
viral
HSV, VAV, CMV, PML (JC virus)
fungal
Thrush (Candida albicans), cryptococcosis (cryptococcal meningitis), histoplasmosis, Pneumocystis pneumonia
protozoan
toxoplasmosis, cryptosporidiosis
Prions
p. 204
Multiple choice: Prions are -- 1) infectious proteins ONLY 2) infectious RNA 3) infectious DNA 4) infectious proteins occasionally mixed with nucleic acids
1) infectious proteins
Name examples of prion diseases
CJD, kuru, scrapie, "mad cow"
Jeopardy style: pathologic prions take on this conformation
What is beta-pleated sheet
Prions are associated with ___________ encephalopathy
spongiform
Microbiology -- systems
p.204-205
Normal flora: dominant
p. 204
Name the dominant normal flora in each of these areas:
skin
Staph epidermidis
nose
Staph aureus
oropharynx
Strep viridans
dental plaque
Strep mutans
colon
Bacteroides fragilis > E. coli
vagina
Lactobacillus, colonized by E. coli and group B strep
Common causes of pneumonia
p. 204
Name the common causes of pneumonia in the following age groups:
Children (6 weeks to 18 yrs)
Virus (RSV), Mycoplasma, Chlamydia pneumoniae, Strep pneumoniae
Adults (18-40 yrs)
Mycoplasma, Chlamydia pneumoniae, Strep pneumoniae
Adults (40-65 yrs)
Strep pneumoniae, H. influenze, Anaerobes, Viruses, Mycoplasma
Elderly
Strep pneumoniae, viruses, anerobes, H. Influenzae, Gram-negative rods
An AIDS patient comes into your office with symptoms of pneumonia. What organisms are you considering?
Staphylococcus, gram-negative rods, fungi, viruses, Pneumocystis carinii
A patient in the CCU gets pneumonia. What organisms are you thinking?
Nosocomial infections are usually Staphylococcus and gram-negative rods
The same patient also aspirated some peas prior to getting sick. What organisms do you add to your list?
Anaerobes
His domineering wife of this same patient is mad because he also had a viral infection last week. What infectious agents would you now consider?
add H. influenzae; another common postviral pneumonia bug is Staph
The wife is so distressed she goes into labor and gives birth to a 10 lb baby girl, who also gets pneumonia. Does she have the same bug as her dad in the CCU?
Neonatal pneumonia is usually due to Group B streptococci or E. coli -- the dad could have the latter.
Of course, the wife get sick too, but her pneumonia is classified as "atypical." What might she have?
Mycoplasma, Legionella, Chlamydia
Cause of meningitis
p. 205
Name the causes of meningitis in the following age groups:
Newborn (0-6 months)
Group B strep, E. coli, Listeria
Children (6 mo to 6 years)
Strep pneumoniae, Neisseria meningitidis, Haemophilus influenze type B, Enteroviruses
6-60 years
N. meningitidis, Enteroviruses, S. pneumoniae, HSV
60+ years
Gram-negative rods, Listeria
An AIDS patient comes to you with high fevers, stiff neck, and mental status changes. What organisms might be causing his meningitis?
Cryptococcus, CMV, toxoplasmosis (brain abscess), JC virus (PML)
CSF findings in meningitis
p. 205
You do a spinal tap on your patient. The CSF pressure appears to be increased. What type of infectious agent have you eliminated?
none. It could be bacterial, TB, fungal, or viral (in viral, CSF pressure is normal to increased)
You do a quick smear of the spinal tap under the microscope and see increased polys. What type of infectious agent does this suggest?
bacterial. In fungal, TB, and viral, you see increased lymphocytes.
The lab tests show an increase in protein and a decrease in sugar in the CSF. Does that confirm your previous guess or confuse you?
Confirms. These findings are seen in bacterial, fungal, and TB infections. In viral infections the protein and sugar concentrations of the CSF are normal.
Osteomyelitis
p. 205
What population is most likely to get osteomyelitis?
children
What lab test is elevated in osteomyelitis?
ESR
For each of the following groups of persons, name the organism that is most likely to cause osteomyelitis
Most people (nonspecific)
S aureus -- assume S aureus if no other information
sexually active
Neisseria gonorrhea (rare -- septic arthritis is more common)
drug addicts
Pseudomonas aeruginosa
Sickle cell Px
Salmonella
Prosthetic replacement
S. aureus and S. epidermidis
Vertebral
Mycobacterium tuberculosis
Urinary tract infections
p. 205
What 2 groups of males are likely to get UTIs?
old men with enlarged prostates and baby boys with congenital defects
What are symptoms of pyelonephritis?
fever, chills, flank pain, CVA tenderness?
What are symptoms of a UTI?
dysuria, frequency, urgency, suprapubic pain
The 2nd most common cause of UTI in young, ambulatory women is __________________
Staphylococcus saprophyticus
Your patient gets a UTI while in the hospital. What organisms do you want to make sure his antibiotics cover while his urine culture is growing?
E. coli, Proteus, Klebsiella, Serratia, Pseudomonas
What are predisposing factors for UTIs?
female gender (10:1; short urethra colonized by fecal flora), flow obstruction, kidney surgery, catheterization, gynecologic abnormalities, diabetes, pregnancy
UTI Bugs
p. 206 "SSEEK PP"
Has a blue-green pigment and fruity odor
Pseudomonas aeruginosa
Two UTI bugs that are nosocomial and drug resistant
Pseudomonas aeruginosa and Serratia marcescens
Leading cause of UTIs
Escherichia coli
What does Proteus mirabilis produce?
Urease
Serratia marcescens produce what color pigment?
red
Large mucoid capsule and viscous colonies
Klebsiella pneumoniae
What do E. coli colonies show on EMB agar?
metallic sheen
2nd leading cause of UTIs in sexually active women
Staphylococcus saprophyticus
Associated with struvite stones and swarming on agar
Proteus mirabilis

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