Sketchy Micro Flashcards
Associate bird or bat droppings with what fungus?
Histoplasma
also spelunking
Where is histoplasma endemic to?
Midwestern US
How is histoplasma transmitted?
Spores, airborne
How big is histoplasma as compared with RBCs?
Smaller
Many histo spores (ovoid bodies) can be found within macrophages
What kind of fungus is histoplasma?
Dimorphic
Mold in the cold, yeast in the heat
What is the treatment for histoplasma?
Itraconazole
The calcified granulomas of histoplasma resemble what infection
TB
Where is blastomycosis endemic to?
Great lakes, Ohio River Valley, Southern US
Is blastomycosis dimorphic?
Yes
Mold in the cold, yeast in the heat
How is blastomycosis transmitted?
Inhalation of spores
How big is blastomycosis w/r/t RBCs?
Almost the same size as RBCs
How would a CXR look of a person with a blastomycosis infection?
Hazy, with patchy alveolar infiltrate
Disseminated infection with blastomycosis, as with an immunocompromised patient, presents with
Skin and bone issues such as osteomyelitis
T/F: Infection with blastomycosis can be either acute or chronic.
True
How is blastomycosis diagnosed?
KOH wet mount;
Culture;
Urine antigen test
How is blastomycosis treated?
azoles for local infection, ie itraconazole
amphotericin B for disseminated infection
How does blastomycosis appear under the microscope?
Broad based budding (looks like balls)
Where is coccidiodes endemic to?
Southwestern US
How is coccidiodes transmitted?
Inhalation
Earthquakes are a risk factor bc of dust.
What kind of organism is coccidiodes?
Dimorph
Mold in the cold
Spherules of endospores in the heat
How big is coccidiodes w/r/t RBCs?
Bigger than RBCs
What is the presentation of coccidiodes infection in a healthy person?
Asymptomatic subclinical - pneumonia-like with coughing and arthralgia
What does the CXR of a patient with coccidiodes infection look like?
CXR can show cavities or nodules
Seeing erythema nodosum on a patient with coccidiodes indicates what clinical scenario?
It indicates that the patient is having a robust immune response
Infection of coccidiodes in an immunocomprimised patient would show what?
Skin and bone involvement, as well as meningitis
How is coccidiodes diagnosed?
KOH
Culture
Serology for IgM
What is the treatment for coccidiodes?
Local lung infection, can use azole drugs;
Systemic infection, use amphotericin B
What is the regional distribution of paracoccidiodes?
South America
How does paracoccidiodes appear?
Captain’s wheel - multiple buds from one single center
What fungal form does paracoccidiodes assume in the lung?
Yeast in the lung;
Mold in the environment
What size is paracoccidiodes w/r/t RBCs?
Paracoccidiodes is larger than RBCs
What is the mode of transmission for paracoccidiodes?
Respiratory droplets
What are the symptoms of infection with paracoccidiodes?
Coughing
Cervical lymphadenopathy
Granulomas in lungs
Mucocutaneous lesions
How is infection with paracoccidiodes treated?
Itraconazole for mild infection;
Amphotericin B for severe infection
What is a unique feature of cryptococcus neoformans?
cryptococcus neoformans is heavily encapsulated
**Has a repeating polysaccharide capsular antigen which lends itself to being tested with the latex agglutination test
Where is cryptococcus neoformans found?
Soil
Pidgeon droppings
Can stay infectious for a LONG time
What is the mode of transmission of cryptococcus neoformans?
Inhalation
Primary focus of infection is the lungs
Is cryptococcus neoformans urease (+) or (-)?
Urease (+)
What population is most at risk for infection from cryptococcus neoformans?
The immunocomprimised, particularly HIV patients
How does infection with cryptococcus neoformans present?
Cryptococcal pneumonia, fever, cough, dyspnea
What is a severe presentation of cryptococcus neoformans infection?
Meningitis, often results in neurological deficits
How is cryptococcus neoformans grown in culture?
Sabauraud’s agar
silver stain = methanamine
red stain = mucicarmine
Under the microscope, what feature does cryptococcus neoformans have?
Wide capsular halo
On gross pathology, what distinctive features does cryptococcus neoformans have?
Soap bubble lesions on gray matter of brain
What is the treatment for infection with cryptococcus neoformans?
Amphotericin B and flucytozine (and fluconazole) - joint
What populations are particularly susceptible to infection with mucormycosis?
Leukemics
Diabetics
Neutropenics
(immunocompromised)
How is mucormycosis (or rhizopus) transmitted?
Spore inhalation
**DKA (excess ketones, as with unmanaged diabetes, is a major risk factor)
How does mucormycosis appear?
Wide angle branching rods, nonseptate
Where does mucormycosis like to profilerate?
Blood vessels
Where does mucormycosis like to go when it infects?
It like to cross the cribiform plate and go to the brain, it creates gigantic lesions ie rhinocerebral mucormycosis, results in eschars (abscesses) on the face
How is infection with mucormycosis treated?
Surgical debridement of necrotic tissue
Amphotericin B
this baby is a killer**
What bacterial infection is often fatal in burn patients?
Pseudomonas
Pseudomonas is: Gram \_\_\_ Shape: Oxidase \_\_\_ Catalase \_\_\_ Capsule or no capsule?
Gram (-) encapsulated bacillus Oxidase + Catalase + (associated with chronic granulomatous disease) Obligate aerobe enterobacteriaciae
What is the #1 cause of nosocomial pneumonia?
Pseudomonas;
common cause of respiratory failure in CF patients
Pseudomonas can progress to what infection in diabetics and IV drug users?
Osteomyelitis
Erythema gangrenosum are black skin lesions caused by sepsis induced by what organism?
Pseudomonas
Exotoxin A is a virulence factor of what bacterium?
Pseudomonas
How is pseudomonas treated?
Pipercillin/tazobactam;
Aminoglycosides in combination in beta lactams;
Fluroquinolones for UTI (indwelling catheter patients)
Psuedomonas can cause what pruritic papulopustular infection?
Hot tub folliculitis - underchlorination of hot tubs
Legionella causes what 2 presentations?
- Legionnaire’s disease - atypical pneumonia seen in smokers;
- Pontiac fever - self-limiting
What stain should legionella be visualized with?
Silver stain
Legionella is a gram (-) bacillus but can’t use H&E
Oxidase (+)
How is legionella transmitted?
From the source, not contagious person to person
How is legionella grown?
Special agar - buffered charcoal yeast extract w/ cysteine and iron
What is seen on CXR of a patient with Legionnaire’s diseasE?
Patchy infiltrate with consolidation of 1 lobe
A patient has the following symptoms: Hyponatremia; Neurologic symptoms - HA, confusion; Diarrhea; High fever; Pneumonia-like symptoms What is the likely pathogen?
Legionella
How is legionella diagnosed?
Culture respiratory sputum
Special agar - buffered charcoal yeast extract w/ cysteine and iron
Visualize with silver stain OR
Rapid urine antigen test
What is the treatment for legionella?
Macrolides
Fluoroquinolones
What is the taxonomy of Coxielle Burnetti?
Gram (-)
Obligate intracellular
Q Fever is caused by what pathogen?
Coxielle Burnetti
How is Coxiella Burnetti transmitted?
Kicked up in dirt and farm animal droppings - aerosol transmission;
Or vets that deal in the birth of farm animals (placental secretions)
What are the symptoms of Q fever?
Caused by Coxielle Burnetti: Pneumonia HA fever HEPATITIS*** usually self-limiting
What is a rare complication of Q fever (Coxiella Burnetti) that can be seen in immunocompromised patients?
Endocarditis
The wheal seen in a + PPD is what type of hypersensitivity reaction?
Type IV
What virulence factors prevent TB from being destroyed?
Cord factor - serpentine shape - prevents mycobacterium from destruction;
Sulfatides allow TB to survive in macrophages and prevent formation of the phagolysosome
What is the taxonomy of Mycobacteerium tuberculosis?
Acid-fast
Obligate aerobe
What is a tuberculoma?
Cavitary lesion in the brain caused by TB infection
What is the acronym for TB treatment?
RIPE
Rifampin - Isoniazid - Pyrazinamide - Ethambutol
The tuberculoid form of M. leprae infection is what kind of immune response?
Th1 - cell-mediated immunity - body can contain infection within macrophages
presents with well-demarcated, hairless plaque on skin
The lepromatous form of M. leprae infection is what kind of immune response?
Th2 - humoral response - body cannot contain infection within macrophages - reason for neuropathy and lesions on extensor surfaces, leonine facies
Is there human to human transmission of M. leprae?
Yes, esp where lepromatous form predominates
What is the reservoir for M. Leprae in the U.S.?
Armadillo
Name the virus:
Naked
DNA virus
#1 cause of tonsillitis
Adenovirus
common cause of conjunctivitis also
What populations are at risk for getting adenovirus?
Military recruits (can receive a live vaccine);
People who swim in public pools;
Children
What virus is responsible for the complication of hemorrhagic cystitis?
Adenovirus
Aspergillus fumigatus is a conidia that shares what feature with bacteria?
It’s catalase +
Aflatoxins that cause hepatocellular carcinomas are what kind of aspergillus?
Aspergillus FLAVUS
How does aspergillus appear under the microscope?
Acute angles (
How is aspergillus transmitted?
Inhalation
Aspergillus causes what kinds of infections?
THREE:
- Allergic bronchopulmonary aspergillosis (ABPA) -
- Aspergillomas - balls of fungus in the lungs
- Angioinvasive Aspergillosis - WORST
Allergic bronchopulmonary aspergillosis (ABPA) is what kind of hypersensitivity reaction?
Type 1
Wheezing, fever, **migratory pulmonary infiltrate, increased IgE
can be seen in CF patients
What patient populations are at risk for developing aspergillomas?
TB, Klebsiella patients
What patients are at risk for Angioinvasive Aspergillosis?
Immunocomprimised
Kidney failure, ring-enhancing lesions on brain, Endocarditis, necrosis around nose due to spread to paranasal sinuses
Treat with ampho B, surgical debridement as necessary
Aspergillosis, except for the most severe form, is treated with:
“conazoles” ie Voriconazole
Orthomyxovirus is responsible for what disease?
Influenza BITCHES
3 strains - A, B, C
8 segments –> relates to how the virus can mutate
What is the taxonomy or orthomyxovirus?
RNA
(-) sense
Enveloped
What is unique about orthomyxovirus as an RNA virus?
It’s the only RNA virus that replicates in the nucleus
Influenza A is responsible for what kinds of outbreaks?
PANdemics and epidemics
Pandemics - antigenic SHIFT - changes in Hs and Ns on surface antigens to form new viruses (reassortment)
Epidemics - antigenic DRIFT - point mutations
Influenza B is responsible for what kinds of outbreaks?
Just epidemics
Epidemics - antigenic DRIFT - point mutations
How does Tamiflu work?
NA inhibitor
Prevents NA from breaking viral babies free from sialic acid;
must give early in the course of the disease
How is influenza (orthomyxovirus) transmitted?
Respiratory droplets
What vaccines are available for influenza (orthomyxovirus)
Trivalent - 2A and 1B strains
Quadrivalent - 2A and 2B strains
can receive >6 months of age
What is the major complication of influenza (orthomyxovirus)?
Pneumonia, often by Staph aureus or Strep pneumo;
Guillain-Barre syndrome (high protein, low WBC in CSF)
What is the taxonomy of Paramyxovirus?
Single strand
RNA virus
(-) sense
Replicates in the cytoplasm
Why is the MMR vaccine not indicated for pregnant patients?
It’s live-attenuated
Associate the 4 C’s: Cough, Coryza, Koplick spots and Conjunctivitis, with what viral illness?
Measles (Rubeola)
caused by Paramyxovirus
4 days of that stuff, followed by a maculopapular rash that becomes confluent and is itchy, Starts on face and moves down the body
What are the complications of measles (rubeola)?
Pneumonia
SSPE - subacute sclerosing panencephalitis - can happen years later, no tx for it
What virulence factors does paramyxovirus-rubeola have?
Hemagglutinin
Fusion proteon –> multinucleated giant cells –> syncytia
**Vitamin A admin reduces virulence factors and complications
Mumps is caused by what kind of virus?
Paramyxovirus
RSV is caused by what kind of virus?
Paramyxovirus
Croup is caused by what kind of virus?
Paramyxovirus
Hemagglutinin, Fusion Protein and Neuraminidase are virulence factors of what paramyxovirus?
Mumps
Where does mumps replicate?
Parotid glands
Can cause orchitis and meningitis
What is the most common cause of pneumonia and bronchiolitis in infants?
RSV
Infiltrates on CXR
What is the only virulence factor of RSV?
Fusion protein (syncytia formation)
Seal bark and inspiratory stridor are characteristic of what paramyxoviral infection?
Croup aka laryngotracheobronchitis
A pediatric patient with Croup would likely have a CXR showing:
Steeple sign - narrowing of subglottal region
Croup has what virulence factors?
Croup is a paramyxovirus - parainfluenza:
HA, NA, fusion protein
What is the gram (-) rod is responsible for causing whooping cough (100 days cough)?
Bordatella pertussis
Highly contagious - transmission via respiratory droplets
Bloodwork of a patient with whooping cough would show what abnormality?
Leukocytosis
How does the bordatella pilus work to infect cells?
Filamentous hemagglutinin attaches, pertussis toxin exotoxin causes ciliary stasis and death of ciliated cells
Which bordatella vaccine is used in the U.S.?
Acellular (DTaP), has a shorter window of effectiveness than the killed version (used abroad)
Bordatella pertussis is treated with:
Macrolides
Name the pathogen:
Gram (-)
Coccobacilliary
Grows on chocolate agar with factors V and X
Haemophilus influenzae
How is Haemophilus influenzae transmitted?
Aerosol
Pneumonia, Epiglottitis, Meningitis and Otitis media are three presentations of what gram (-) bacterium?
Haemophilus influenzae
What patient population is more at risk for Haemophilus influenzae infection?
Splenectomized patients (SCD) - can develop sepsis or septic arthritis
The Haemophilus influenzae vaccine covers what type?
Type B (the cause of meningitis, encapsulated)
What are the symptoms of epilglottitis caused by Haemophilus influenzae?
Inspiratory stridor;
“cherry red epiglottis;”
drooling
What is indicated for close contacts of a patient with Haemophilus influenzae?
Rifampin prophylaxis
