micro Flashcards

1
Q

woman with a painful vaginal ulcer and bilateral inguinal lymphadenopathy. negative tzanck and VDRL.
dx and tx?

A

haemophilus ducreyi, chancroid

tx - ceftriaxone or azithromhcin

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2
Q

virus with the leading risk for developing hepatocellular carcinoma?

A

hepatitis b

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3
Q

kaposi sarcoma belongs go which viral family?

A

hhv 8

herpes viruses incl hsv1 hsv2 and roseola (hhv6), EBV, CMV, and varicella

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4
Q

CSF for bacterial meningitis will have what characteristics?

A

high opening pressure
high protein
pleocytosis with PMN predominance
low glucose

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5
Q

previously healthy pt with a history significant only for mitral valve prolapse presenting with endocarditis like symptoms

A

strep viridans:

s. mutans
s. sanguinis
s. oralis
s. mitis

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6
Q

tx for hhv8?

A

alpha interferon

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7
Q

oxidasd negative motile GNR that is beta hemolytic on macconkey agar but light green with black centers on hektoen agar

A

salmonella

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8
Q

pt with new palpitations, chest pain, systolic murmur (mitral regurg), elevated cardiac enzymes. bx would show diffuse myocardial defeneration and necrosis with inflammatory infiltrate

A

cozsackie virus

naked ssrna

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9
Q

h. pylori infection is a risk factor for?

A

gastric adenocaecinoma and b-cell hodgkin gastric lymphoma (AKA MALT lymphoma)
most h. pylori infections are asymptomatic (not manifesting as PUD in the majority)

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10
Q

what PPE is recommended in a ptmwith c. diff?

A

non sterile gloves and gown

also must use soap and water to wash hands. alcohol based sanitizer is not sufficient

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11
Q

a pt with chronic granulomatous dz are at increased risk of infection with organisms with which feature?

A

catalase positive organisms
pt is NADPH osidase deficient
s. aureus, burkholderia cepacia, serratia, nocardia, aspergillus

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12
Q

what is burkholderia cepacia?

A

catalase positive, non lactose fermenter, gram neg cocobaccilli
opportunistic pathogen causing pneumonia in immune compromised hosts(cf, cgd)

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13
Q

a pt presents with mycoplasma pneumonia and anemia. he is given azithromhcin and both symptoms improve. why?

A

m. pneumoniae can cause intravascular hemolytic anemia due to similar Ags and cold agglutinins. the anemia resolves when the cold agglutinin IgM levels lower.
m. pneumo is also associated with stevens-johnson syndrome, arthralgia, encephalitis, arrythmia, and bullous myringitis

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14
Q

an infant presents to the er following a seizure and a 12 hour history of fever. 3 days after discharge she develops a maculopapular rassh on her trunk. dx?

A

roseola (hhv6)
the key is a high fever followed by a maculopapular rash on the trunk 3-5 days later
tx = supportive

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15
Q

unvaccinated kid presents with fever, runny nose, cough, bilateral conjunctival injection, and small white spots with erythematous base on buccal mucosa. dx and likely to develop what additional symptom?

A

rubeola (measles)

maculopapular rash

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16
Q

a pt with a history of smoking and alcohol abuse presents with malaise and cough with 2 month duration. yellow sputum with streaks of blood. poor dentition, ginivitis, and large submandibular nodes. ronchi in right upper lobe.

A

actinomycosis
systemic infection occurs when mucosa is disrupted (poor dentition)
pulmonary actinmycosis can follow aspiration.
dx - filamentous branching pattern
tx -penicillin

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17
Q

a kid presenting with epiglottitis probably has what in his history?

A

missed his H. flu vaccine.

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18
Q

presence of pyrrolidonyl arylamidase is associated with?

A

Strep pyogenes

PYR positive

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19
Q

pt on chemo presents with skin patches with an ulcerated appearance and occasional necrotic center.
increased PTT, neutropenia

A

psuedomonas aeruginosa

ecthyma gangrenosum is caused by psuedomona bacteremia

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20
Q

pt is newly diagnosed with CML and begins tx. later presents with HA and an eye problem. PE shows tenderness of paranasal sinus, left orbit swelling, cellulitis, mild proptosis, ptosis. bx shows hyphae with acute angles

A

aspergillus fumigatus

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21
Q

Nicotinic blockade (diplopia, dysphagia) and muscarinic blockade (dry mouth) is suggestive of

A

The 3 D’s suggests Ingestion of C. botulinum toxin
Inhibits ACh release
Can be partially overcome by high-rate repetitive nerve stimulation (CMAP)

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22
Q

Tx of a pt with a recent heart valve replacement pt that has cultures poitive for cat + coag - Staph

A

Staph epidermidis

Vanco

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23
Q

Kidney transplant patient with pleuretic chest pain, cough, and low grade fever. Infiltrate in lower lobe of lung. Not responding to abx. Brnchoalveolar lavage reveals red round organism on mucicarmine staining

A

Cryptococcus neoformans
This is the only pathogenic fungi with a polysaccharid capsule (virulence factor). Stains red with mucicarmine
Can present as meningoencephalitis or lung dz in immunocompromised

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24
Q

Characteristics of scarlet fever (S. pyrogenes

A

fever, pharyngitis, sandpaper-like rash, circumoral pallor, strawberry tongue

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25
Physical characteristics of candida
Pseudohyphae with bloastoconidia
26
Physical characteristics of blastomyces
Yeast with distinctive broad-based budding
27
Physical characteristics of Coccidioides
Spherules with endospores
28
Physical characteristics of cryptococcus
Capsule (India ink stain)
29
Physical chracteristics of Histoplasma
Small oval yeast within macrophages
30
Nearly all Candida infections can be treated with
fluconazole
31
Woman with recurrent transient pulmonary infiltrates and history of bronchial asthma, especially in winter. She does use albuterol. Labs demonstrate Eosinophilia. CT shows proximal bronchiectasis.
Aspergillus fumigatus Allergic bronchopulmonary aspergillosis Pts with a history of asthma or CF are prone to allergic hypersensitivity reaction to the fungus.
32
Pt with persistant fever, chills, fatigue, dyspnea for 10 days. History significant for splenectomy and recent travel to Conneticut. Bilateral infiltrates on CXR. Labs show normocytic normochromic anemia with a cross-shaped intraerythrocytic inclusion
Babesiosis Tick borne infection (like borrelia) Coinfection is common
33
Live cycle of Hep B
dsDNA -> +RNA template -> dsDNA progeny
34
Apiration pneumonia
Lung parenchyma infection Aspiration of oral microbes (anaerobes) Presents days after aspiration with fever, cough, and sputum. Usually in RLL and can progress to abscess Tx - Clindamycin
35
Aspiration pneumonitis
Lung parenchyman inflammation Aspiration of gastric contents presenting hours after event. Range os symptoms and CXR infiltrates resolve without abx Tx - supportive
36
Farm worker presenting with shortness of breath, fatigue, myalgia, and severe retroobital headaches. Elevated ALT/AST and throbocytopenia
Coxiella burnetii Q fever - acute phase Inhalation of bacteria from animal waste Fatal if untreated and progressis to infective endocarditis
37
A female pt presents with pelvic pain, fever, and chills following a D&C 2 days ago. On PE she has lower abdominal tenderness, an open os, foul-smelling tissue in vaginal canal and moderate CVA tenderness
Septic abortion = infection of the retained products of conception in the uterus S. aureus is the most common cause but can also be E. coli, Group B strep Organisms usually stay in the placenta but pt can become septic if they enter the intervillous space Tx - abx and surgical evacuation Can have long term complications (Asherman syndrome) involving adhesions in the uterus leading to amenorrhea and infertility
38
Co innoculation of H. flu and S. aureus allows H. flu to grow larger colonies on sheeps blood agar. Why?
S. Aureus provides NAD+ (Factor V) "satellite phenomenon" | Hemattin (Factor X) will be released from lysed RBC's
39
How do you manage a pt with a recent staph infection that presents with fever and tenderness over the upper lumbar vertebrae without overlying skin changes?
Pt probably has vertebral osteomyelitis. Hmatogenous spread. Initial evaluation should include blood cultures and MRI of the spine.
40
If soil is heated to 100C for 15 min what bacteria could survive?
Bacillus anthracis | Just because it's in the soil in the form of a spores. Spore forming bacteria can survive boiling water
41
reovirus with dsRNA
Rotavirus
42
Flu-like febrile illness with myalgia, joint pain, retro-orbital pain, bleeding, rash, thrombocytopenia, leukopenia, and elevated LFT's following travel to mexico
Dengue Hemorrhagic fever Do have life long immunity following infection, but can get a secondary infection with a different serotype and can cause a more severe illness
43
Sexually active female pt with UTI. Organism is Gram + cocci, catalase +
S. saprophyticus | Also noboviocin resistant
44
Pt being treated for Hodgkins dz presents with fever, chills, and malaise. Culture grows Gram positive rods with a very narrow zone of beta hemolysis on blood agar and grow well in the cold.
Listeria monocytogenes Need cell-mediated immunity to clear them Tumbling motility at 22C
45
A neonate presents with clenched muscles and difficulty feeding following an uncomplicated home delivery. The umbilical cord with covered with soil. Other than hygienic umbilical cord care, what other strategy could have prevented the condition?
Neonatal tetanus | Prevent with: good hygienic umbilical care and vaccination of the pregnant mom
46
A grandfather had HA, myalgia, malaise, cough, and throat pain and was set home on conservative management. He presents 5 days later with dyspnea, chest pain, and productive cough and is admitted
Pt initially had influenza Elderly pts can develop a secondary bacterial pneumonia due to damaged mucocilliary epithelium. Generally acquire Strep pneumo, Staph aureus, or H. flu
47
How does Corynebacterium diphtheriae acquire virulence?
Transduction or lysogenization of exotoxin (Tox gene)
48
A pt with C. diff is placed on a po macrocyclic abx that is bacteriocidal and minimal systemic absorption
Fidaxomicin | inhibits RNA polymerase
49
What is the most important factor in the pathogenesis of Shigella dysentery
Mucosal invasion (M cells that overlie Peyer's patches)
50
The virulence in rabies is due to its ability to bind which receptor?
Nicotinic Acethlcholine receptors
51
A kid has a 2 day history of diarrhea and his puppy had diarrhea about a week ago. Kid is up to date on vax. Stool is negative for ova and parasites
Campylobacter jejuni can be transmitted from animal to human. Yersinia too Abdominal pain can mimic appendicitis
52
What is malignant otitis externa?
Severe ear infection seen in DM pts. Presents with ssevere ear pain and drainage and granulation tissue. Can progress to osteomyelitis of the skull Pseudomonas aeruginosa - non lactose fermenting, oxidase +, Motile GNR Tx - Ciprofloxacin
53
A pt with recent viral esophagitis and pneumocystis pneumonia is presenting with meningitis. CSF has high protein and pleocytosis. Positive latex agglutination for soluble polysaccharide Ag
Pt likely has HIV Meningitis due to cryptococcus neoformans Light microscopy of CSF would reveal budding yeast.
54
The adult version of the S. pneumo vaccine contains which components?
Outer polysaccharide covering | This is found in both the conjugate and unconjugated vaccines
55
A pt with pyelonephritis has a culture positive for motile Gram negative rods demonstrating a green metallic sheen on eosin methylene blue (EMB) agar and hemolysis on blood agar
E. coli | Major virulence factor in UTIs = Fimbrial Ag
56
What perinatal care should be given to prevent a Strep aglactiae infection in a neonate?
Interpartum ampicillin
57
pt presents with fever and jar pain. PE shows a swelling of the postauricular area extending to the angle of the mandible. Dx?
Parotitis ( due to dehydration, intubation) S. aureus Elevated amylase confirms dx
58
Where is the primary site of ribosome synthesis and assembly?
nucleolus | All ribsomal rRNA is made here except 5S
59
A double stranded linear segmented RNA virus?
Rotavirus
60
Vector in Trypanosoma cruzi?
Reduviid bug
61
A gram + diplococci that causes pneumonia
S. pneumo
62
Staghorn calculi are formed by?
``` Urease producing microorganisms Staph species Ureaplasma Proteus (most common) Klebsiella Pseudomonas ```
63
What is a worrisome complication of mucormycosis?
Meningitis
64
A pt presents with right upper quadrant pain, jaundice, and fever
Bacterial cholangitis Long history of gallstones causes blockage of the bile duct leading to infection. Bacterial infection of bile duct. Usually enteric GNR
65
Most common cause of osteomyelitis in a healthy child
S. aureus
66
Most likely cause of meningitis in a 2 day old infant?
Group B strep | Most common cause in kids
67
A female is brought to the ED for suspected appendicitis, but US revealed that the mass was within the pelvic cavity. She needs a different emergent surgical procedure
Chlamydia | Causes scarring of the fallopian tubes leading to ectopic pregnancy
68
A viral cause of seizures in an HIV pt with a CD count of 150
HSV 1 or HSV 2
69
Good alternative to treat gram + organisms in a pt allergic to penicillin
Macrolides (erythromycin)
70
a pt has a sore throat, hoarseness, productive cough, and elevated gamma-glutamyltransferase level. CXR shows lobar pneumor. Tx = cefuroxime. Dx?
Klebsiella pneumoniae Nosocomial and CA pnumonia Chronic alcoholics have elevated gamma-glutamyltransferase GN encapsulated rod on sputum smear mucoid colonies on MacConkey tx = second gen cephalosporin and an aminoglycoside
71
A homosexual man with steatorrhea
Giardia
72
Viruses of the reoviridae family have what characteristics?
ds segmented RNA with icosahedral nucleocapsids | IE - rotavirus, coltivirus
73
What step of proteins translation does C. dpitheriae's toxin inhibit?
EF2 toxin inhibits elongation (translocation) Complexes with GTP to bind the ribosome
74
a pt with a history of mitral valve prolapse presents with subacute endocarditis that are throwing microemboli in the hands (Janeway, Osler), retina (Roth spots) dx?
Step veridians | Most commone cause of SAE in the setting of mitral valve prolapse
75
A pt with Aschoff nodules and a new murmur
Rheumatic heart dz
76
10 y/o with seizures, poor school performance, CSF findings consistent with viral infection. Respiratory secretions + multinucleated giant cells with intracytoplasmic and intranuclear inclusions. Rash on the trunk
Measles
77
I a pt has a penicillin allergy they should receive?
Erythromycin | Macrolide against Gram + and Gram -
78
A neonate presents with conjunctivitis on day 13 of life. Dx?
Chlamydia trachomatic (D-K) at risk of getting pneumonia
79
Trismus is?
Lock jaw | Seen in tetanus
80
Tenesmus?
Sensation of needing to empty the bowel although there is no stool to pass. Inflammatory dz of the bowel
81
Ziehl-Neelsen stain is used for?
Acid fast bacteria (M. TB)
82
Schistosoma haematobium causes which type of bladder cancer?
Squamous cell carcinoma (SCC) | Keratin pearls on bx
83
Which other organism carries a toxin with a similar MOA as Bacillis anthracis?
Edema factor = increase in intracellular cAMP | Also seen in cholera toxin
84
Germ tube postivie fungus
Candida albicans | Germ tube = hypahe
85
Germ tube negative fungus
histoplasmosis, blastomycosis, coccidioidomycosis
86
HIV pt (CD4 = 22) with hemiparesis, visual defects, cognitive impairment. Negative LP but bright spots are seen on the MRI. Dx?
JC virus Multifocal leukoencephalopathy CD4
87
Regan Lowe medium is used for?
Bordetella pertusis | Culture from a calcium alginate swab (bacteria do not transfer well on cotton)
88
What infection can occur when an HIV pts CD4 count drops
Disseminated Mycobacterium avium-intracellulare infection TB like dz Azithromycin prophylaxis
89
A 12 y/o presents with mental status changes characteristic of encephalitis x 1 wk. CSF has elevated WBCs, mildly elevated protein, and RBCs. CT show focal unilateral pathology of the temporal lobe. Dx?
Encephalitis due to HSV1 | elevated proteins + RBCs in CSF = HSV1 encephalitis
90
A poultry farmer in ohio presents with pneumonia. XR lesion in the upper lung lobe and hilar lymphadenopathy. Dx?
Histoplasmosis Ohio and Mississippi river valley Found in bat droppings
91
7 y/o immigrant presents with red itchy eyes with swelling, cough, runny nose. Oral cavity has small lesions with white centers. Dx?
Rubeola (measles) 2 C's - cough, coryza, conjunctivitis, and Koplick spots Expect to see a rash 1-2 days after the appearance of the Koplik spots that will start at the head and move its way down
92
What is the neurological syndrome associated with Rubeola infection
Subacute Sclerosing panencephalitis (SSPE) Occurs 7-9 years after Rubeola infection Personality changes, lethargy, difficulty in school, odd behavior. Can progress to dementia, myoclonic jerking, and eventual flaccidity a decorticate rigidity.
93
After a camping trip that included interaction with many types of animals a pt presents with RUQ pain, nausea, and vommiting. An enlarged liver with a cyst is found. Dx and Tx?
Echinococcus granulosus Albendazole parasitic tapeworm in feces (dog) Albendazole inhibits tubule polymerization. Cannot go straight to surgery b/c the contents of the cysts causes anaphylactic shock
94
Which organisms cause struvite stones?
``` Urease positive Proteus Klebsiella Staphylococcus Ureaplasma Pseudomonas Alkaline urine with multiple magnesium ammonium phosphate crystals ```
95
What is the MOA of enfuvirtide?
Prevent entry of viral particles into the target host cell (gp41 mediated fusion)
96
What is the MOA of rltegravir?
Inhibits integrase and prevents viral integration into the host genome
97
MOA of maraviroc?
entry inhibitor | Binds CCR-5 on T cells and monocytes and block its interaction with gp120
98
Specific test for Syphillus infection?
Fluorescent treponemal antibody absorption test | VDRL and RPR are more sensitive but less specific
99
Virulence factor that allow S. pneumo to colonize the lung?
IgA protease | cleaves secretory IgA Ab in mucosal surfaces allowing for bacterial colonization
100
Which bacteria have lipopolysaccharide?
outter membrane of Gram-negative bacteria. Induces a strong immune response by the host
101
Pt presents with high fever, black vomitus (dark-colored blood in the vomitus as a result of GI bleeding), jaundice, HA, and back pain. Dx?
Yellow fever, flavivirus Dx with rtPCR Bx = councilman bodies (acidophilic inclusions in liver), but bx is usually not recommended due to bleeding risk
102
How is be facial n. palsy differentiated from stroke?
If the pt can furrow the brow - stroke | if the whole half of the face is paralyzed - borrelia
103
What syx are found in the second phase of Borrelia infection?
CN VII palsy, transient arthralgias, aV nodal block, secondary annular rash, carditis Tx - doxycycline However, if pt has cardio or neuro involvement tx with IV ceftriaxone
104
What makes Bells palsy different from facial n. palsy?
Bells palsy is idiopathic origin | Facial n. palsy is a known cause (ie borrelia)
105
A woman presents with a vaginal infection due to candida following a course of tetracycline. Why?
Loss of gram + faculative anaerobes Lactobacilli make up the normal vaginal flora Dx - KOH prep
106
What type of Hypersensitivity rxn is PSGN
``` Type III (Arthus rxn) Ag-Ab complexes are deposited in the GBM and activates complement ```
107
What is a type II HS rxn?
Ab mediated but IgG binds Ag on the surface of a target cell - autoimmune
108
In CMV retinitis, what would be a late finding in the dz?
Retinal detachment CMv is a common cause of blindness in AIDS pts Presents with rapidly diminishing sight and on fundoscopy cotton-wool exudates, necrotizing retinitis, perivascular hemorrhages, and ultimately retinal detachment Tx - ganciclovir and foscarnet
109
Which two toxicities are associated with isoniazid use?
Neurotoxicity (Add B6) | Hepatotoxicity
110
Infectious cause of CHF in a pt with no RF's?
Coxsackie B | Icosahedral member of the picornaviridae family
111
Which two agars can be used to culture Bordetella pertussis?
Bordet-Gengou (potato) agar Regan-Lowe medium Transfer with calcium alginate swab
112
Major cause of viral pink eye?
Adenovirus Naked icosahedral dsDNa Self-limited, no tx
113
When would you use Loffler medium?
Corynebacterium diptheriae
114
Maraviroc prevents?
CCR-5 binding to gp120
115
Enfuvirtide prevents?
gp41 mediated fusion
116
Why does Hep D need Hep B?
Coating of the viral particles | HDV needs HBV sAg so that it can enter future hosts
117
When Aspergillus forms a fungus ball within a preexisting cavity, what is this process?
Colonizing | Causes a lung hypersensitivty rxn in allergic bronchopulmonary aspergillosis in individuals with asthma
118
PSGN is which type of HS rxn?
Type III = Ag - Ab complexes leading to complement activation Type II = Ab mediated
119
What is a clue cell made of and which infection does it suggest?
Clue cell = epithelial cell covered with gram-variable rods Gardnerella vaginalis Thin off-white discharge with fishy odor, imbalance of vaginal flora, see clue cells on wet mount pH > 4.5, + whiff test (amine odor with KOH) Tx - metronidazole or clindamycin
120
In TB cord factor is?
A virulence factor | Inhibits PMNs, destroys mitochondria, and increases release of TNF
121
8 y/o presents with rapid and irregular movements of his hands and funny faces. He also has several circular, faintly erythematous lesions on his abdomen. What is the mechanism?
Cross-reactivity of Ab against bacterial and host Ag | Anti-M Ab cross-react and attack cardiace and CNS Ag
122
If a person has Anti-HBs Ab then they?
Have been vaccinated against HBV
123
Why add clavulanic acid to amoxicillin treatments?
Decrease drug cleavage by bacterial cells Sulbactam and tazobactam are beta-lactamase inhibitors. Expands amoxicillin specturm of actitivy to include stains of B-lactamase synthesizing bacteria
124
MOA of zidovudine?
Inhibits 3'-5' phosphodiester bond formation Nucleoside reverse transcriptase inhibitor Thymidine analog (no 3'OH group)
125
A pt tests positive for HBsAG and elevated LFTs. The most likely outcome of the infection is?
Complete resolution | 95% of HBV infected adults have acute hepatitis with mild or subclinical syx that eventually completely resolve
126
What mechanism do bacteria use to become resistant to rifampin?
Alter structure of enzymes involved in bacterial RNA synthesis Inhibits bacterial RNA polymerase Red-orange body fluids Inhibits transcription
127
Pt presents with a urethral dischage that is rich in neutrophils with intracellular gram negative diplococci. He is given IM ceftriaxone but his syx do not improve. What tx should he receive next?
PO azithromycin It should have been assumed that he had a co-infection of neisseria and chlamydia and he should have received ceftriaxone + doxy or azithromycin
128
Tx for enterobius?
Albendazole Scotch tape test worm Pyrantel pamoate - 2nd line
129
What is the mechanism for naficillin tx is Staph aureus?
Poor interaction with binding proteins | Altered penicillin-binding protein in the peptidoglycan cell wall that does not bind beta-lactams effectively
130
Elderly pt presents with acute mental status change, seizure, HA, focal neurologic deficits. CSF reveals hemorrhagic lymphocytic pleocytosis with NL glucose. ABN MRI signal in the temporal lobes. Dx?
HSV encephalitis | Tx - acyclovir
131
A pt with methicillin-resistant S. aureus and started on an IV abx. A week later he has mascle pains and elevated creatine phosphokinase that resolves with d/c. What is the MOA of the abx?
Maintenance of membrane potential Daptomycin - gram positive organisms. Causes depolarization of bacterial cellular membrane and inhibition of DNA, RNA, and protein synthesis. Dapto is associated with increased creatine phosphokinase and increased incidence of myopathy
132
A pt with primary TB infection is put on Isoniazid monotherapy. This would result in?
Selective survival of bacterial cells secondary to gene mutation Active TB is never treated with monotherapy due to the fast emergence of mycobacterial abx resistance from rapid, selective gene mutations.
133
A strain of Candida develops a mutation in the enzyme responsible for synthesizing a fungal cell wall polysaccharide. This strain would be resistant to?
Caspofungin Inhibits the synthesis of the polysaccharide glucan Azoles, Ampho - inhibits ergosterol in the cell MEMBRANE
134
What lab findings would suggest that a HBV pt has progressed to chronic HBV?
If HBeAg persists for several months and host anti-HbeAg remains low, suspect chronic HBV with high infectivity
135
Which antifungal causes a decrease in ergosterol incorporation into the cell membrane
``` Nystatin Polyene antifungals (ampho, nystatin) act by binding ergosterol in the funagl cell membrane ```
136
MOA of Triazoles
Inhibit ergosterol synthesis | -azoles
137
MOA of Fluctosine
Converted to 5-fluorouracil interferes with fungal RNA and protein synthesis
138
HIV pt presents with esophageal hyperemia and linear ulcerations. Dx?
CMV
139
HIV pt presents with patches of adherent grey/white pseudomembranes on endoscopy. Dx?
Candida
140
HIV pt presents with small vesicle and "punched-out" ulcers on endoscopy. Dx?
HSV-1
141
Pseudomonas treatments
Penicillins - ticarcillin, piperacillin Cephalosporins - ceftazidime, cefepime aminoglycosides - amikacin, gentamicin, tobramycin fluoroquinolones - ciprofloxacin, levofloxacin Monobactams, carbapenems
142
Pt presents with mono syx with 30% atypical lymphocytes. Serum fails to agglutinate horse RBCs. Dx?
CMV + agglutination (monospot) would suggest EBV other causes of monospot negative mono are HHV6, HIV, and toxo
143
A DM pt presents with a black eschar around his nasal cavity. What test would confirm the dx?
Mucosal bx | Mucormycosis
144
Pathogenecity of H. flu depends on?
antiphagocytic polysaccharide capsule
145
Primary causes of hepatic abscesses?
underdeveloped country - parasitic (Entamoeba, echnococcal) | Developed country - bacterial (S. aureus)
146
Pt in the north east presents with flu like syx on intraerythrocytic inclusions on smear. Dx?
Babesiosis Ixodes tick vector Maltese cross
147
Pt with a UTI has gram-positive cocci in chains. Dx?
``` Enterococcus gram positive cocci in pairs or chains No hemolysis on blood again (gamma) Pyrrolidonyl arymlamidase (PYR) + Grow in bile and 6.5 % NaCl Negative nitrites on UA ```
148
S. pneumo vaccine for adults includes which component?
Outer polysaccharide covering Induces a T cell independent response Also N. meningitidis and H. flu
149
S. pneumo vaccine for kids contains?
Conjugate vaccine = polysaccharide material attached to a protein Ag, more robust T cell response
150
Pt has a lung bx with spherules packed with endospores. Dx and recent hx includes?
Coccidioides | Recent travel to Arizona
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Fungus passed through bird droppings?
Cryptococcus - pigeons, immunocompromised meningitis | Histoplasma - Mississippi and Ohio river basins, bird and bat droppings. Hx of cleaning bird coops or caving
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Fungal rhinosinusitis with acute angles and septations
Aspergillus Occurs in immunocompromised pt Granuloma formation in the lung V-shaped, narrow branching hyphae Septations look like little bubbles within the organism on bx Monomorphic, grows on decaying vegetation Tx - Amphotericin
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What process is most important for eliminating Listeria from the body?
Cell-Mediated Immunity Intracellular bacteria are protected from circulating immune factors (Ab). Listeria is able to live within the macrophage with the action of listeriolysin O (pore-forming toxin selectively activated within acidified phagosomes) Beta hemolytic (narrow), tumbling motility, grows at cold temps Neonates are especially susceptible up to 3 months of age due to naive cell-mediated immunity Contaminated dairy products
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Skin lesions following the lymph nodes following a thorn prick
Sporothrix schenckii Bx = granuloma with histiocytes, multinucleated giant cells, PMNs, surrounded by plasma cells Forms subQ noddules and ulcers along the lymphatics Dx - by culture Tx - Itraconazole
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EBV binds which host cell receptor for entry?
CD 21
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Parvovirus binds which host cell receptor for entry?
RBC P Ag
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Small ovoid bodies with Macrophages
Histoplasma Seen in BM bx of immunocompromised Hyphae on sabouraud agar Can be dx'd with immunoassay and serology
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nonlactose-fermenting, oxidase +, motile, GNR
Pseudomonas Causes malignant otitis externa in elderly DM pts Exquisite ear pain and drainage with granulation tissue in the ear canal
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Doubly refractile wall with single broad-based bud
Blastomyces | Ohio miss river
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Thick walled spherule filled with endospore
Coccidioides | Southwest
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PYR +
Enterococcus | Strep pyogenes
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CMV infection during pregnancy increases the risk of what to the unborn fetus?
``` Chorioretinitis Sensorineural deafness Seizures Jaundice Microcephaly ```
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HHV 6 is? Syx?
Roseola | Occurs in
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flulike illness + myalgias + retro-orbital pain + recent travel hx
Classic dengue fever If pt also has thrombocytopenia and petechiae - Dengue hemorrhagic fever ssRNA viruses with 4 serotypes, Flavirus
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Why is HCV considered genetically unstable?
Lacks proofreading 3'-5' exonuclease activity in its RNA polymerase Glycoprotein sequences also have a hypervariable region prone to mutation
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Bartonella causes cat scratch fever and?
Bacillary angiomatosis in the immune compromised, culture negative endocarditis Axiallary lymphadenopathy is common
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Noneveloped ssDNA virus?
Parvo
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Most common Catalse Problem organisms?
``` S. aureus Burkholderia Serratia Nocardia Aspergillus Beware of these in a pt with Chronic Granulomatous dz (NADPH oxidase deficiency) ```
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All rRNA (except 5S) is transcribed in the?
Nucleolus Dense round structure Contains ribosomal DNA, newly transcribed rRNA, and ribosomal proteins
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Why do asplenic pts have more severe syx?
Defect in systemic bacterial clearance Fxn of spleen red pulp = 1. Filter blood, 2. Site of opsonizing Ab synthesis (esp important for clearing encapsulated species) Asplenic pts are prone to infection by encapsulated organisms (S. pneumo, H. flu, Neisseria)
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What are the key characteristics of HSV encephalitis?
Potentially fatal complication of primary dz or reactivation | Necrosis of temporal lobe causing aphasia, personality changes, and classic syx of encephalitis
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Changes in host range of a virus are usually due to a mutation in the?
Surface glycoprotein | Mediates virion attachment and fusion
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STD with Deep, purulent painful ulcers with matted/suppurative lymphadenitis?
Chancroid Haemophilus ducreyi Dx - Gram stain, culture, PCR
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STD with Painless, progressive, red serpiginous ulcerative lesions without lymphadenopathy
Klebsiella granulomatis | Dx - Gram stain, culture (tough), Bx (Donovan bodies)
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Pt presents with vomiting two hours after ingesting a food with mayo. Dx?
S. aureus Exotoxin was formed prior to ingestion B. cereus also creates a stable exotoxin but look for hx of eating reheated rice
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Diplopia Dysphagia Dysphonia
Botulism (12-36 hrs post consumption) Dysphonia = difficulty speaking Toxin prevents release of ACh
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PE - tonsilar erythema with exudates | Microscopy - clumped Fram + bacter with polar granules that stain deeply with aniline dyes
Corynebacterium diphtheriae Inhibits host cell protein synthesis by catalyzing the ADP-ribosylation of host cell elongation factor-2 Nonmotile, unencapsulated GPR found in cumps. Cytoplasm contains metachromatic granules that stain with aniline dyes (methylene blue)
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Cause of cephalosporin resistant meningitis in a kid
Listeria 1st line tx = ampicillin Causes dz in those with deficient cell-mediated immunity (kids and immunocompromised) Cephalosporins would cover - H. flu, Neisseria, Srep agalactiae, strep pneumo)
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HBV genome replication cycle
dsDNA -> + RNA -> dsDNA progeny | Replicates via reverse transcription
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Genome, syx, tx, and route of transmission of adenovirus
Genome - dsDNA syx - red eyes in croseded quarters (camp, military, dorms) tx - supportive transmission - direct contact, fecal-oral, respiratory droplets
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HIV pt presents with tonic clonic seizure and two ring-enhancing focal lesion with surrounding edema in R frontal lobe. Dx?
Toxo - multiple ring-enhancing lesions with mass efect Tx - Pyrimethamine + sulfadiazine, or pyr + clindamycin if allergic to sulfa drugs Also add leucovorin (folinic acid)
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Atypical pneumonia + watery diarrhea + smoking hx + recent travel on a cruise
Legionella | hyponatremia
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Suspect gonorrhea and tx with?
Macrolide (chlamydia) and 3rd generation cephalosporin (ceftriaxone) (gonorrhea)
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Morphology of Bordetella pertussis
Gram-neg coccobacillus
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Which cell type secretes IFN gamma in a quantiferon test?
Th1 | Macrophages secrete IL-2
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Pt presents with pruritic rash (worse at night) on the palmsa. excoriations with small crusted red papules. Dx?
Scabies | Dx with skin scrapings from lesions showing mites, ova, and feces
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MOA of isoniazid
Inhibits mycolic acid synthesis | Pathogen loses its acid fastness and stop proliferating
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MOA of rifampin?
Inhibit bacterial DNA dependent RNA pol
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Major virulence factor in epiglottitis?
Polyribosylribitol phosphaste | component of H. flu's capsule
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A virus is identified to have a membrane envelope with a similar composition as its host. What could it be?
CMV, EBV, HHV etc Herpesviruses bud through and acquire the lipid bilayer envelope from the host cell nuclear membrane Most other viruses bud through the host membrane without acquiring a phospholipid membrane
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Immigrant presents with tonic-clonic seizure. On MRI there is a cyst in the left sylvian fissure that has minimal enhancement and no associated edema. Dx and mode of transmission?
Neurocysticerosis Ingestion of Taenia solium (pork tapeworm) eggs from the stool of tapeworm carriers (fecal oral route) Common cause of seizures in central and south america NOTE - eating contaminated meat does not cause neuro syx, just tapeworm infestation, nbd
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What is used to treat rabies?
Inactivated vaccine | syx - agitation and muscle spasms progressing to coma
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Infant with irritability, poor feeding vomiting, large head circumference. white-yellow chorioretinal lesions bilaterally. Enlarged ventricles with intracranial calcifcation on CT. Dx?
Toxo Torches infection Hydrocephay + intracranial calcification + chorioretinits
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Agar for C. diptheria?
Cysteine-tellurite agair Loffler's medium (kid laughing at the telle)
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How can you distinguish between toxo and Neurocysticercosis (Taenia solium) on seizure pt?
Immunocomp pt - Toxo | Travel to South America - Taenia
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How does TB's cord factor establish virulence?
PMN inhibition Mitochondrial destruction TNF release
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E. coli is able to cause sepsis by entering through the?
Urinary tract | Fimbriae are essential for colonization
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Cause of fulminant hepatitis in pregnant women?
``` Hep E Unenveloped, ssRNA Fecal-oral Asia, Africa, Mexico No chronic dz Higher mortality in preggo's ```
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Fxn of the virulence factor found in the Peptidoglycan wall of S. aureus?
Protein A | binds the Fc portion of IgG -> impairs complement activation, opsonization, phagocytosis
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Congenital rubella syndrome
classic triad = white pupils (congenital cataracts) + sensory-neural deafness, PDA But also microcephaly, deafness prevent with live MMR vax
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Older woman is presenting with encephalitis, meningitis, flaccid paralysis, and a rash. dx?
``` West Nile virus (Flavivirus) Encephalitis + flaccid paralysis + rash + ssRNA Mosquito borne, see transmission in the sumer Tx - supportive ```
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Tx plan for cryptococcal meningitis?
Amphotericin B + flucytosine | followed by long term fluconazole
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MOA of C. diff toxin?
Compromises the cytoskeleton integrity of intestinal mucosal cells Disrupt actin cytoskeletal structure and intracellular signaling toxin A - causes more inflammation and fluid secretion (enterotoxin) Toxin B - is more cytotoxic
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Why does HDV need HBV?
Coating of viral particles
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Non lactose fermenting GNR causing syx in a pt with an indwelling catheter?
Pseudomonas aeruginosa
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If you see viral gastroenteritis in US school kids assume it is?
Norovirus | Rotavirus has similar syx but rarely seen in the US due to vax's
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Most likely route of infection of Listeria in immunocompromised?
Contaminated food
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Water borne gastroenteritis with high mortality in Asian countries. Oxidase-positive GN bacilli that grow well on highly alkaline selective media?
Vibrio Thiosulfate citrate bile salts sucrose again (TCBS) Pts with achlorhydria (low gastric acid production) can get the disease from a lower infectious dose (this includes taking omeprazole)
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Following an influena infection a pt presents with pneumonia due to?
Bacterial pneumonia | S. pneumo > S. aureus > H. flu
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Pt presents with appendicitis. Most likely organism?
Usually polymicrobial with Bacteroides fragilis and E. coli
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Botulinum toxin blocks?
Presynaptic excocytosis of ACh vesicles
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In Mycoplasma pneumo, which Ab's cause the hemolytic anemia?
Cold agglutinins
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While in central america a pt develops watery diarrhea with cramps n/v that resolves two days later w/o abx?
``` ETEC "traveler's diarrhea" Heat labile (LT) and/or heat stable (sT) enterotoxins are endoded on a plasmid LT = cholera like toxin, increases intracellular cAMP in gut mucosal cells by activating Gs ST = increases cGMP ```
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Tx for pseudomonas?
cephalosporins (Cefepime, ceftazidime) | Penicillins (ticarcillin, piperacillin)
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Pt has dysuria and hematuria 2 weeks after visiting africa. U/S bilateral hydronephrosis and bladder wall thickening. Dx?
Schistosomiasis haematobium Transmitted by snails S. japonicum and S. mansoni cause intestinal and hepatic schistosomiasis
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Lobar pneumonia in an alcholoic is caused by?
Aspiration of oropharyngeal contents (anaerobic bacteria: Fusobacterium, Peptostreptococcus, Bacteroides) Common cause of lung abscesses
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A baby born to a mom that was infected by HBV during the third trimester is likely to have elevated levels of what in her serum?
HBeAg | Infected neonates are at high risk for chronic infection but are usually asymptomatic with very minor clinical findings
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Pt has pneumonia in the RUL. Encapsulated GNR that ferments lactose
Klebsiella pneumoniae
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Linear ulcerations in immunocompromised?
CMV
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Infection post dog bite that has mouse like odor on culture?
Pasteurella multocida | Tc - amoxicillin + clavulanate
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A woman has a stillbirth at 18 weeks gestation that has pleural effusion, pulmonary hypoplasia and ascites. Dx?
Parvo Nonenveloped ssDNA Mom had reported arthralgias Fetal hydrops = pleural effusion with secondary pulmonary hyoplasia and ascites
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Grayish white vaginal discharge Fishy odor Clue cells
Gardenella Anaerbobic gram variable rod Add KOH = whiff test Tx - metronidazole, clindamycin
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MOA of edema factor
Adenylate cyclase that increases intracellular cAMP -> PMN and macrophage dysfunction and tissue edema Found in Bacillus anthracis and Bordetella pertusis
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Infant presents with winter cough and difficulty breathing. Diffuse expiratory wheezes and scattered rales throughout
RSV
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How do we prevent vertical transmission of HIV1?
Antiretroviral therapy All HIV + moms should take ART regardless of CD4 count or viral load 2 NRTs + protease inhibitor/NNRT/integrase Infants will generally receive several weeks of zidovudine
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Group A strep is resistant to phagocytic killing when placed in fresh human blood. This could be overcome by adding Ab against?
Protein M - major virulence factor, inhibits phagocytosis and activation of complement NOT: Streptolysin O - lyses RBCs Steptokinin - catalyzes plasminogen to plasmin to facilitate strep spread
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A medium containing vancomycin, colistin, nystatin, and trimethoprim favors growth of?
Neisseria gonorrhoeae Thayer-Martin selective medium Chocolate agar + Vanco, colistin, nystatin, trimethoprim
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Which cause of gastroenteritis has a small infectious dose?
Shigella flexneri | Also entamoeba and Giardia
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Most important factor in pathogenesis of Shigella?
Mucosal invasion Non-motile, non-lactose fermenting organism Mucosal invasion of M cells that overlie Peyer's patches
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Pt develops parotitis following intubation. What serum marker would be useful in dx?
``` Elevated Amylase (nut lipase WNL to rule out pancreatitis) Typically in post op or post intubated elderly pts. Usually S. aureus ```
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Pneumonia + intranuclear cytoplasmic inclusion bodies in a post lung transplant pt?
CMV enveloped dsDNA virus Owl's eyes
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How do you treat C. diptheriae?
Passive immunization
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aedes aegypti transmit which 2 diseases?
Dengue Fever - retrorbital pain + joint and muscle pain | Chikungunya - Flu like + polyarthralgias + rash
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Filamentous bacteria with pulmonary, skin, and CNS syx?
Nocardia
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Pt with flu like illness, retroorbital headace with recent exposure to animal waste (farm animals)
Coxiella burnetii | Q fever
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HSV1 acquires acyclovir resistance from co culture with HSV 2 and the progeny continue to be resistant. What is the mechanism?
Recombination Gene exchange through cross over Can't be phenotypic mixing because the progeny would have lost resistance
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A strain of M. TB has decreased activity of intracellular catalase peroxidase. It would be resistant to?
Isoniazid INH prevents mycolic acid synthesis and INH must be processed by mycobacterial catalase peroxidase for the drug to be activated within the bacteria