Micro Flashcards
1
Q
P. jiroveci
CD4 count, risk factor, prophylaxis
A
CD4 <200/mm3
oropharyngeal candidiasis increases risk
TMP-SMX
2
Q
Toxoplasma gondii
CD4 count, risk factor, prophylaxis
A
CD4 <100/mm3
positive Toxoplasma IgG is a risk factor
TMP-SMX
3
Q
Mycobacterium avium complex
CD4, prophylaxis, pathogenesis in HIV, signs/symptoms, biopsy
A
CD4 <50/mm3, prevent with Azithromycin
ingestion/inhalation > prevents phagolysosome formation > insufficient IFN-y to activate macrophages in CD4 defic.
nonspecific sx (fever, weight loss, D); anemia, HSmegaly, high ALP/LDH with RES involvement
dx by blood culture (but slow); biopsy shows granulomas of foamy epitheliod cells + giant cells with IC acid-fast bacilli
4
Q
Congenital Toxoplasmosis: when does baby get it and what it do
A
in utero transplacental infection
triad = intracranial calcifications, chorioretinitis, hydrocephalus
also hepatosplenomegaly, neuro issues (seizure, eye movement problems, altered muscle tone) and rash
5
Q
Congenital HSV: when does baby get it and what it do
A
intrapartum infection
causes ophthalmia neonatorum (also via Chlamydia or Neisseria, conjunctivitis)
6
Q
Clostridium septicum
what does it cause? in whom specifically?
A
gram-pos, spore-forming, exotoxin-producing normal flora
spontaneous gas gangrene in patients with underlying COLON CANCER, IBD or immunosuppression (is normal gut flora that can get into circulation when mucosa is compromised
RAPID ONSET MUSCLE PAIN, fever, HEMORRHAGIC BULLAE, dusky skin, edema + CREPITUS
7
Q
Vibrio vulnificus
A
gram-negative
increased risk for fulminant infection in HEMOCHROMATOSIS b/c needs free iron for growth
rapid-onset sepsis and bullous skin lesions
shellfish consumption or wound infection with seawater
8
Q
fungal infection from indwelling catheter
what microbe + what sx?
A
candidemia
sepsis, abscess, and pustular skin lesions with red base
9
Q
multiple myeloma-related common infections
A
lung - S. pneumo or H. flu
UTI - E. coli
10
Q
differentiation of EBV vs. non-EBV infectious mononucleosis
causes of non-EBV IM
A
non-EBV IM often does NOT have sore throat or lymphadenopathy or heterophile Ab positivity
CMV IM can come from blood transfusions (irradiation of blood products reduces risk)
other causes of IM-like syndromes are HHV-6, HIV and toxoplasmosis
11
Q
a glycosylated HIV polyprotein that is cleaved into 2 smaller proteins
what is it? what are the 2 smaller proteins? functions of resulting proteins and why are they glycosylated?
A
GP160 is cleaved into GP120 and GP41 (Gp160 glycosylated in rER and Golgi)
gp120 is an envelope protein that mediates viral attachment
gp41 is an envelope protein that mediates fusion
glycosylation helps with immune evasion (masks antigens), host cell binding + proper protein folding
12
Q
main mechanism of aminoglycoside resistance
how does this mechanism arise in microbes?
A
antibiotic-modifying enzymes (acetylases, kinases, etc.)
aminoglycosides altered by acetylation, etc. have reduced binding of the 30S ribosomal subunit (16S component)
usually via PLASMID or TRANSPOSON transfer, not chromosomal mutation
13
Q
3 infections assoc. with acute pancreatitis
A
mumps
Coxsackie
Mycoplasma
14
Q
Staph epidermidis
biochem tests + microbiological characteristics
A
catalase-positive (as are all Staph)
coagulase negative (differentiates it from aureus)
gamma-hemolytic (no hemolysis)
novobiocin sensitive (diff from saprophyticus)
gram-positive cocci in clusters
adhesion + biofilm proteins > infects prosthetics
15
Q
Histoplasma capsulatum
general characteristics, transmission + pathogenesis
dx (culture, labs + characteristic signs)
A
dimorphic, transmitted by inhalation > transforms to yeast in lungs
replicates in phagosomes of macrophages > oval/round yeast cells in macros
intact immunity > asymptomatic or self-limited pulmonary infection (cell-mediated immunity)
impaired immunity > RES dissemination with HSmegaly, LAP, and PANCYTOPENIA
dx by BLOOD/URINE Ags, hyphae on Sabouraud culture and characteristic TONGUE ULCERS
16
Q
Schistosoma haematobium
where? how? what it do?
A
Africa and Middle East - URINARY schistosomiasis
freshwater snails release larvae > penetrate skin > migrate to + mature in liver > travel to bladder venous plexus
terminal hematuria, dysuria + frequent pissing
hydronephrosis, pyelonephritis and bladder SCC
17
Q
Schistosoma mansoni / japonicum
where? how? what it do?
A
Mansoni - Africa, Middle East, S. America + Carribean
Japonicum - Asia, Philippines, Japan
same pathogenesis as haemotobium, but travels thru portal veins to GI
intestinal schisto - D and pain, ulceration with IDA
hepatic schisto - HSmegaly, periportal fibrosis + portal htn
all 3 spp. have Th2 granulomatous response with eosinophils and M2 macrophages
18
Q
Echinococcus granulosus
transmission + disease
A
DOG TAPEWORM - dog host (sheep intermediate)
food contaminated with dog poop > hydatid cysts
19
Q
Diphyllobothrium latum
transmission + disease
A
FISH TAPEWORM - raw freshwater fish
vitamin B12 deficiency and megaloblastic anemia
20
Q
Taenia solium
transmission + 2 diseases
A
PIG TAPEWORM - undercooked pork (worm infection) or eggs in carrier feces (cysticercosis)
21
Q
Parvovirus B19
type of virus? transmission?
A
naked ssDNA
respiratory, hematogenous or congenital transmission
22
Q
Parvovirus B19
prodrome and 2 clinical manifestations in normal patients
A
Prodrome - HA, coryza, GI sx (heavy viremia + shedding)
Erythema Infectiosum - in KIDS; bright red cheek rash, circumoral pallor, fever +/- reticular rash on arms, legs, trunk
Acute arthropathy - in ADULTS; polyarthritis that is SYMMETRIC on PIP, knee and ankle joints; self-limited + non-destructive
(both have immune complexes + low shedding)
23
Q
Parvovirus B19
2 clinical manifestations in unique types of patients
A
Aplastic crisis - “reticulocytopenia” in pts with pre-existing RBC issues such as sickle cell or spherocytosis
Hydrops fetalis - pregnant woman infected > hydrops in baby is common; direct hemolysis + precursor interruption
24
Q
Asplenic patient
more susceptible to infection with which bacteria? (general type + species examples)
A
encapsulated bacteria
group B strep (agalactiae) H. flu Strep pneumo Meningococcus Salmonella typhi
25
Malarial life cycle
| this card is a nightmare, just for review
Anopheles bite > SPOROZOITEs infect hepatocytes
in liver - dormant infection with HYPNOZOITEs or a SCHIZONT of many MEROZOITES forms in liver cell > schizont rupture releases merozoites to blood
in blood - merozoites infect RBCs and form TROPHOZOITES > asexual formation of more schizonts in RBCS with further merozoite release or...
gametocyte formation > picked back up by mosquitos
26
Toxocara canis
manifestations? dx?
DOG ROUNDWORM - incidental infection in humans
eosinophilic GRANULOMATOUS inflammation
visceral LARVA MIGRANS
ocular larva migrans
dx by serology
27
Oncogenesis by HBV vs. HCV
| 1 mechanism for both, 2 mechanisms unique to only 1 of them
1. Increased Hepatocyte Turnover - with local inflammation > incr. mutation risk (both HBV + HCV)
2. Genome Integration - only HBV! partial dsDNA integration into host genome via topoisomerase I can cause insertional mutagenesis
3. Oncogenic Viral Proteins - viral protein "HBx" activates cell growth genes + interferes with p53 (HBV only!)
28
MCC of sepsis in asplenic pt?
MCC of osteomyelitis in asplenic pt?
prevention?
Sepsis - S. PNEUMO > H. flu > (E. coli, pseudomonas, staph, other strep)
Osteomyelitis (in sickle cell) - SALMONELLA > (S. aureus, E. coli)
penicillin prophylaxis and pneumococcal vaccination
29
Mefloquine
active against what phase of malarial life cycle? clinical consequence?
a SCHIZONTICIDE that kills replicating parasites IN RBCS
does NOT kill hepatic schizonts (is inactivated in liver)
must take for 4 WEEKS after return (liver schizonts rupture after 8-30 days)
30
Plasmodium in Africa is often which species?
Resistant to what?
Treated with what?
Falciparum
chloroquine-resistant
mefloquine, doxycycline or atovaquone-proguanil
31
Zika virus
pathogenesis? clinical? dx?
ssRNA Flavivirus; TRANSPLACENTAL transmission; targets NEURAL PROGENITORS
microcephaly, craniofacial disproportion; SPASTICITY + SEIZURE; ocular issues
imaging - calcifications, ventriculomegaly, cortical thinning
RNA detection by PCR of urine, serum or CSF
32
Shigellosis
infects which type of cells? then what?
(most common species? other species)
infects "MICROFOLD (M) CELLS" of GI mucosa (at base of villi in Peyer's patch in ileum)
is endocytosed, lyses the endosome, multiplies and spreads laterally to other cells > denuding + ulceration of mucosa > bloody D
33
HIV biding, fusion + entry process
gp120 binds CD4 plus CCR5 or CXCR4 co-receptors
gp120 undergoes conformational change to expose gp41 which mediates fusion
(Maraviroc blocks CCR5; enfuvirtide blocks gp41)
34
Two HIV regulatory genes
| not gag, pol, env
Nef - regulates MHC-I expression on infected cells
Tat - transcriptional activator, promotes viral gene expression
35
MCC viral meningitis in children
what else can it cause, more rarely?
Enterovirus, specifically Coxsackie B
more rarely, encephalitis with flaccid paralysis
36
What kind of organisms are CGD patients susceptible to?
CGD = NADPH oxidase inactivation > no ROS formation
CATALASE-POSITIVE MICROBES - without catalase, microbes can't prevent H2O2 accumulation from THEIR OWN metabolism in phagosomes > hypochlorite is formed + damages microbe; with catalase, H2O2 is broken down
37
What are the 5 most common organisms that infect CGD patients?
CATALASE-POSITIVES:
```
S. aureus
Burkholderia cepacia
Serratia marcescens
Nocardia
Aspergillus
```
38
Molecule linked to PG wall in Gram-positive microbes only
Teichoic acid
Ag determinant for microbe ID and Ag target for immune system
39
Which bacteria produce IgA protease? (4)
what does it do?
Neisseria (both), S. pneumo, H. flu
Cleaves IgA at its hinge region > Fab and Fc fragment
facilitates bacterial mucosa adherence
40
Bacillus anthracis
antiphagocytic feature
D-glutamic acid capsule
41
B. anthracis
toxins
edema factor - adenylate cyclase
lethal factor - hydrolyzes MAPK kinases
42
B anthracis
culture + micro characteristics
large, nonmotile, spore-former
nonhemolytic, gram-positive rod
cultures grow curled edges with "MEDUSA HEAD" shape
43
B anthracis
severe form of disease + its signs
Hemorrhagic Mediastinitis in "Pulmonary Anthrax"
prodrome > widened mediastinum on x-ray
can cause shock, brain edema/hemorrhage + death
seen in woolsorters and mail sorters
44
"Genetic Reassortment" in viruses
what happens? what kind of viruses / example?
another name for the result
2 strains infect same cell > SEGMENTS reassort > progeny with reassorted genomes (since genome is changed, progeny of the progeny will retain same changes)
SEGMENTED viruses only
in cause of INFLUENZA viruses, NA and HA are on different segments > novel strain created by reassortment = ANTIGENIC SHIFT
(drift is just point mutations)
45
segmented viruses
| 4
all are RNA viruses
Orthomyxo - INFLUENZA
Arena - LASSA FEVER virus
Bunya - HANTA virus
Reo - ROTAvirus
46
typical HEP B histo picture
"GROUND GLASS" hepatocytes have finely GRANULAR, diffusely homogeneous PALE PINK cytoplasm
due to accumulation of HBsAg in cells
47
typical Hep C histo picture
less specific picture than Hep B (no ground glass)
LYMPHOID AGGREGATES in portal tracts and MACROVESICULAR STEATOSIS
48
Strongyloides stercoralis infection
two larvae types? special infectious mechanism?
roundworm
infection - infectious FILARIFORM larvae in feces soil > penetrate skin > lungs > swallowed > adults lay eggs in GI mucosa > non-infectious RHABDITIFORM larvae release in poo
AUTOINFECTION - some rhabdi larvae molt into filari larvae and auto-infect host > widespread dissemination = HYPERINFECTION
49
Strongyloides stercoralis
hyperinfection in which patients (general answer is obvious but be more specific)
immunocompromised
specif. on drugs or HTLV-1 infection > impaired Th2
50
Strongyloides
s/s? specific findings? tx?
asymptomatic, or...
chronic GI and pulmonary sx
"LARVA CURRENS" - red itchy linear streaks on thigh/butt via subcutaneous larval migration away from butt
Dx - RHABDITIFORM larvae in stool; O+P on GI biopsy
Tx - IVERMECTIN
51
polysaccharide component of Hib capsule
polyribosylribitol phosphate
52
how does PRP capsule of Hib prevent phagocytosis?
binds "FACTOR H" in host circulation
factor H normally degrades C3b deposited on host cells > prevention of C3b deposition on Hib > no opsonization / complement mediated lysis
53
M protein
which microbe? function?
in cell wall of Strep pyogenes
binds factor H > prevents opsonization / complement mediated lysis
54
Protein A
which microbe? function?
cell wall of S. aureus
prevents opsonization by binding Fc region of Igs
55
Aeromonas hydrophila
micro characteristics?
disease?
risks?
oxidase-positive
non-lactose-fermenting
Gram-negative rod
gastroenteritis, wound infection, bacteremia
exposure to contaminated water
56
Pyrrolidonyl arylamidase test (PYR)
S. pyogenes?
S. aureus?
S. pyogenes is PYR POSITIVE
S. aureus is PYR NEGATIVE
57
Best method for confirmatory dx of Trichomonas
Saline microscopy for MOTILE TRICHOMONADS
58
Diff. dx of vaginal infections by vaginal pH
| 3 infections
Bacterial vaginosis and trichomonas show HIGH pH (>4.5)
Candidiasis shows NORMAL pH (3.8-4.5)
59
How to diff btwn two types of gram positive cocci?
Catalase
Staph - cat pos
Strep - cat neg
60
How to differentiate Strep by hemolysis?
alpha hemolytic - slight zone, greenish > S. pneumo + viridans
beta hemolytic - S. agalactiae or S. pyogenes
61
Which 2 types of cat-neg Gram+ cocci are gamma-hemolytic (no hemolysis)?
Enterococci
Strep gallolyticus (bacteremia/infective endocarditis assoc. with colon cancer)
62
How to diff btwn alpha hemolytic strep?
bile and optochin sensitive - S pneumo
bile and optochin resistant - S. viridans
63
How to diff btwn beta hemolytic strep?
S pyo - bacitracin-sensitive and PYR positive
S agalact - bacitracin resistant, PYR negative, and CAMP positive
64
How to diff btwn gamma hemolytic gram+ cocci?
Enterococcus - grow in 6.5% NaCl and bile, PYR positive
S. galloyl - grow in BILE BUT NOT SALT and are PYR negative
65
which two bacteria are PYR positive?
S. pyogenes
Enterococci spp.
66
Campylobacter jejuni
source other than contaminated food?
domesticated animals
especially puppies from kennels
67
#1 cause viral gastroenteritis
transmission? presentation?
Norovirus
feces-contaminated food/water
vomit-predominant illness with pain and moderate amt diarrhea (non-inflammatory, no blood/WBCs in stool)
68
Vibrio parahaemolyticus
where + from what? presentation? worse in whom?
marine environments; contaminated shellfish
diarrhea-predominant gastroenteritis
sepsis in liver disease / HEMOCHROMATOSIS
69
dx for Giardia
| 3 things, first 2 most important
1. Stool O + P
2. Fecal immunoassay for antigens
(3. SI biopsy - villus atrophy + crypt hyperplasia dependent on disease severity)
70
main mechanism for Giardia immunity
considering this, who gets Giardia more?
CD4 function and SECRETORY IgA (binds trophozoites > impaired adherence to upper small bowel wall)
Kids with IgA deficiency, X-linked agammaglobulinemia or COMMON VARIABLE IMMUNODEFICIENCY get giardia more
71
M protein
which microbe? structural homology with what?
S pyogenes
homologous to human tropomyosin and myosin (both have many alpha helices + coiled coils)
cross-rxn with heart myosin > rheumatic carditis
72
prophylaxis for Strep agalactiae
universal screening by maternal vaginal + rectal culture at 35-37 weeks
any woman who is CULTURE POSITIVE or has PAST CHILD AFFECTED should take...
INTRA-PARTUM PENICILLIN (or ampicillin alternative) will prevent sepsis, pneumonia + meningitis in baby
(prepartum penicillin has a risk of re-colonization before birth)
73
Primaquine
unique use in malaria?
kills HYPNOZOITES dormant in liver > prevents disease relapse
74
what 2 plasmodium spp. tend to create hypnozoites?
| consequence? tx?
P. vivax and ovale
| can cause disease recurrence after hypnozoite rupture from liver; tx with primaquine
75
how can LACTOSE-FERMENTING GRAM-NEGATIVE RODS be differentiated in UTIs in women?
differentiates what species?
Indole test - conversion of Trp to indole
E. Coli - indole-positive
Enterobacter cloacae - indole-negative
76
What is FIRST used to differentiate gram-negative rods biochemically?
MacConkey agar
Lactose fermenters form PINK colonies (Klebs, E coli, Enterobacter, Citrobacter, Serratia)
Non-fermenters form WHITE colonies (Pseudomonas, Shigella, Salmonella, Proteus)
77
Among lactose fermenting gram negative rods, how are they differentiated by fermentation speed?
Fast fermenters - Klebs, E. coli, Enterobacter
Slow fermenters - Citrobacter, Serratia
78
Among non-lactose fermenting gram-neg rods, what is the FIRST step in differentiation?
oxidase test
oxidase positive - Pseudomonas
oxidase negative - Shigella, Salmonella, Proteus
79
Among oxidase-negative non-lactose fermenting gram-negatives, how is differentiation performed?
TSI agar ("triple sugar iron")
assesses H2S production (creates BLACK color)
No H2S - Shigella
H2S production (black) - salmonella, proteus
80
#1 COD in patient hospitalized for acute rheumatic fever
PANCARDITIS
| mitral stenosis and its complications come much later
81
HIV increases chances of EBV causing what?
EBV antigen-induced B-CELL PROLIFERATION resulting in Burkitt lymphoma
"immunodeficiency-related" Burkitt is not necessarily in the jaw like endemic... can arise in the GI tract etc.
("starry sky" histo, high Ki-67 fraction, diffuse medium-sized lymphos + a t(8;14) causing c-MYC overexpression)
82
flu vaccines
what 2 types + routes of admin?
who is recommended to get it?
Parenteral inactivated
Nasal spray live-attenuated
anyone over 6; especially health care workers, elderly, chronically diseased or immunocompromised
83
main effect of INACTIVATED flu vaccine on viral function?
induces production of NEUTRALIZING ANTIBODIES against the HEMAGGLUTININ antigen
this inhibits binding of HA to sialylated receptors on host cells and thus INHIBITS VIRAL ENTRY via endocytosis
84
main effect of LIVE ATTENUATED flu vaccines on viral function?
stimulate MHC-I pathway > generate CD8+ cells that kill infected cells
85
Cephalosporin resistant organisms (5 things)
| 3 via one mechanism; 2 via another
Altered PBPs:
1. Listeria monocytogenes - but ampicillin works
2. Enterococcus
3. MRSA
No cell wall:
1. Chlamydia
2. Mycoplasma
86
Congenital Rubella Syndrome
classic triad
2 other possibilities
1. CATARACTS - present as white pupils
2. Sensorineural DEAFNESS
3. PATENT DUCTUS ARTERIOSUS
CV defect can also be peripheral pulmonic stenosis
head defects including microcephaly and retardation
87
What kind of vaccine is MMR?
live attenuated
88
Besides kids 12-15 months and booster at 4-6 years...
who should get MMR vaccine?
non-pregnant women of childbearing age with low/no rubella antibody titer
give MMR and advise to avoid pregnancy for 4 weeks
89
wet mount of CSF of meningitis pt shows MOTILE TROPHOZOITES
what is it? tx?
Primary Amebic Meningoencephalitis
Naegleria fowleri; amphotericin B
90
4 causes of necrotizing fasciitis
1. Strep pyogenes
2. Staph aureus
3. Clostridium perfringens
4. Polymicrobial
91
Aeromonas hydrophila
microbial characteristics
3 diseases via spread by what?
oxidase-positive, non-lactose-fermenting gram negative rod
gastroenteritis, wound infections, or bacteremia after exposure to contaminated water
92
Typhoidal salmonella infection
cause + epidemiology
S typhi and paratyphi
source is HUMANS (unlike S enterica) via contaminated water/food in DEVELOPING countries
93
Typhoidal salmonella infection
pathophys of infection
enterocyte invasion > CAPSULAR ANTIGEN Vi blunts neutrophil response > extensive replication in MACROPHAGES > spreads thru lymph and RES
94
Typhoid fever
s/s
- Progressive fever with PULSE-TEMP DISSOCIATION (relative bradycardia)
- maculopapular "ROSE SPOTS" on trunk
- abdominal pain, HSmegaly, GI bleeds + perforation
95
Other than self-limited diarrhea, what can be some rare complications (3) of non-typhoidal Salmonella?
1. Osteomyelitis
2. Mycotic aneurysm
3. Endocarditis
96
Mechanism of host cell death caused by E. histolytica
contact btwn microbe + host cell inserts an AMEBIC CHANNEL-FORMING PROTEIN in the host cell membrane
97
anti-Campy Abs cross react with what host molecule to cause Guillain-Barre syndrome?
GM1 Ganglioside
98
Babesiosis
s/s (general, and more severe ones)
fever, fatigue, MYALGIA, HA + flu-like sx
```
if severe:
ARDS
CHF
DIC
SPLENIC RUPTURE
```
99
Babesiosis
diagnostic histo (stain + 2 signs)
wright giemsa stain of blood smear
intra-RBC "RING FORMS" - pleomorphic
occasional "MALTESE CROSS" forms
100
Aedes mosquito
what two viruses?
dengue fever + chikungunya
| <14 day incubation
101
3 viruses which can cause dilated cardiomyopathy
Coxsackie B
Adenovirus
Influenza
102
Neurocysticercosis
organism? transmission?
Taenia solium (pork tapeworm)
EGGS excreted in human feces > ingested in contaminated food
(as opposed to eating LARVAE in pork causing normal infection)
103
Neurocysticercosis
where? presentation?
central + south america, sub-saharan africa, asia
LONG INCUBATION (months-years)
seizures, focal neuro sx + intracranial hypertension via CSF OBSTRUCTION
104
Neurocysticercosis
Dx? Tx?
CT/MRI - show cysts + scolex (head of tapeworm with hooklets)
Eosinophilia
high ESR
albendazole
105
What pathophysiological mechanism is responsible for the neural effects of rheumatic fever? (Sydenham's chorea)
cross reactivity between antibodies against microbial N-ACETYL-BETA-D-GLUCOSAMINE, and..
host neuronal LYSOGANGLIOSIDE
106
In utero CMV infection
consequences?
(think senses, CNS and RES)
up to 5% women get primary CMV in preg - 1/3 of these transmit to fetus in utero (mostly 1st trimester)
- Chorioretinitis
- Sensorineural deafness
- Microcephaly + seizures
- HSmegaly + jaundice
107
Causes of reactive arthritis ***other than C. trachomatis***
Enteritis via...
Salmonella, shigella, yersinia, campy or c diff
108
Joint aspirates show what in reactive arthritis?
NO MICROBES - it is not a disseminated infection, but rather an inflammatory reaction caused by the infection
109
Triad for botulism
Diplopia, dysphagia and dysphonia (hoarseness)
both nicotinic and muscarinic blockade via ACh release inhibition
110
How does botulism affect muscle contraction?
How can this be tested?
Flaccid paralysis via decreased ACh release at NMJ
Results in decreased CMAP (compound muscle action potentials) that can be increased again by RAPID REPETITIVE NERVE STIMULATION
111
Where + how should lumbar puncture be performed?
pt recumbent or sitting bent forward
needle inserted btwn L3/L4 or L4/L5 (well below end of SC)
palpate ILIAC CRESTS and find body of L4 between the 2 crests
(goes through interspinous ligament, ligamentum flavum and dura into space containing cauda equina)
112
what do serovars A-C of C. trachomatis cause?
"Trachoma" - ocular infection in children
113
PG precursor disaccharide is made of what 2 molecules?
N-acetylmuramic acid
N-acetylglucosamine
114
What PG cell wall component do penicillins structurally resemble?
D-Ala-D-Ala
| facilitates their binding to TRANSPEPTIDASE > inhibits final "cross-linking" step of wall synth
115
Dengue fever
virus type? primary vs. secondary infection differences?
positive-sense ssRNA flavivirus
4 serotypes DENV1-4
primary infection is often asymptomatic or self-limited + results in immunity to same serotype
secondary infection with DIFFERENT serotype results in MORE SEVERE illness (via Ab-dependent enhancement, more complexes and enhanced T-cell activity)
116
S/S of "classic dengue fever"
- "Break bone fever" - fever with severe myalgia + joint pain
- RETRO-ORBITAL PAIN
- DIFFUSE MACULAR RASH - "white islands in sea of red"
- Leukopenia, thrombocytopenia (EPISTAXIS, PETECHIAE, PURPURA)
117
S/S of "dengue hemorrhagic fever"
especially 1 special sign
- high capillary permeability > worse bleeding than classic form with SHOCK, RESP/CIRC FAILURE
- TOURNIQUET SIGN - petechiae form after 5 minutes of cuff inflation
- thrombocytopenia, prolonged fever
118
What 2 cell types does EBV have tropism for?
Via what receptor?
B cells and nasopharyngeal epithelium
binds to CD21 (aka CR2) on these cells
(this is the receptor for complement C3d; EBV binds it with its gp350)
119
Most common adult meningitis vs. neonate meningitis
Adult - S. pneumo and N. meningitidis
Neonate - S. agalactiae and GRAM-NEG RODS
120
3 most common viral meningitis causes
1. ENTEROVIRUS - most common (coxsackie, echo + polio)
2. Arboviruses
3. HSV - type 2 more common than type 1
121
Difference in WBC count in CSF btwn bacterial and viral meningitis
viral - often <500/mm3 (lymphos)
bacterial - often >1,000/mm3 (neutrophils)
122
Difference in glucose and proteins in CSF btwn bacterial + viral meningitis
Viral - glucose is normal or slightly low; protein is mildly elevated (<150 mg/dl)
Bacterial - glucose is always low (<45) and protein is highly elevated (>250)
123
What are the segmented viruses?
| 4 classes
1. Orthomyxoviruses - influenza
2. Reoviruses - rotavirus, colorado tick virus
3. Bunyavirus
4. Arenavirus
ORBA
124
What can segmented viruses do if 2 different ones co-infect a cell?
REASSORTMENT - genetic shift
genetic segments reassort and create progeny with reassorted genomes (can go on to make more progeny with same genome, unlike when only surface molecules are exchanged)
125
what toxin causes the symptoms of Rotavirus infection? how?
NSP4 - increases chloride permeability in gut > watery diarrhea
126
MacConkey agar
what does it differentiate and how?
lactose fermenters vs. non in gram-neg enteric rods
lactose fermenters lower agar pH and create PINK colonies (E. coli, Enterobacter, Klebs)
non do not create pink (Pseudomonas, Proteus, Salmonella, Yersinia)
(has bile salts + crystal violet to inhibit gram-pos)
127
What can be added to MacConkey to differentiate a certain E. coli strain?
sorbitol - differentiates O157:H7 (enterohemorrhagic)
sorbitol replaces lactose; O157:H7 can't ferment sorbitol > no pink colonies
128
What might the microbe be if it produces pink colonies on MacConkey after a LONG fermentation?
Shigella sonnei
129
What might the microbe be if it produces pink colonies on MacConkey that look moist and sticky?
Klebsiella or Enterobacter
due to polysacch capsule
130
What is EMB agar and what does it differentiate?
eosin methylene blue
isolates enteric pathogens from contaminated specimens; looks for lactose fermentation
lactose fermenters bind dye and produce GREEN METALLIC SHEEN
131
What kind of hemolysis due E. coli produce?
beta hemolysis
132
What is the virulence factor in E. coli for neonatal meningitis?
K1 capsular antigen
133
What is the main treatment for TREATMENT-RESISTANT SCHIZOPHRENIA?
(poor response to at least 2 meds; continued sx)
Clozapine
134
What are the side effects of clozapine? (4)
- Neutropenia - must monitor CBC
- Seizures
- Myocarditis
- Metabolic syndrome
135
Rubella ("German measles")
vs.
Measles (Rubeola) ... rash differences
both are maculopapular, start on face + spread to trunk + limbs
Rubella SPREADS FASTER, but DOES NOT DARKEN OR COALESCE as much as measles
(Rubella also has postauricular/occipital lap)
136
3 viruses with atypical lymphocytes on peripheral smear
1. EBV
2. CMV
3. Hepatitis B
137
How long do antibody responses sometimes take to develop in syphilis?
4 weeks
so RPR, VDRL and fluorescent treponemal Ab absorption tests can be negative
nontreponemal (RPR and VDRL) are more commonly false-negative during this time
138
What is the "skin snip" test used to diagnose?
Onchocerciasis
river blindness via black fly bite
139
Main clostridium perfringens toxin involved in gas gangrene?
alpha toxin
has phospholipase/lecithinase activity > activates DAG and arachidonic acid pathways > TXA2, PAF, IL-8 and edema
140
What is RSV's virulence factor for cell entry?
a fusion protein
141
2 tx for RSV infection
Palivizumab - anti-fusion protein
Ribavirin - guanosine analog halts RNA synth
142
Bacterial infections in patients with LOW B CELLS
Anything encapsulated: picture all the sketchy capsules...
"Please SHiNE SKiS"
```
Pseudomonas
S. pneumo
Hib
Neisseria
E coli
Salmonella
Klebsiella
Strep group B (agalactiae)
```
143
Bacterial infections in patients with LOW GRANULOCYTES
```
Staph
Burkholderia cepacia
Pseudomonas
Serratia
Nocardia
```
are all CATALASE+ ... affect CGD pts without NADPH oxidase bc break down the H2O2 they produce
144
2 bacteria described as "branching + filamentous"
differentiation + tx?
both NOCARDIA and ACTINOMYCES (both Gram+)
```
nocardia = aerobe in soil
actinomyces = anaerobe in oral, GI, repro tract
```
for tx remember "SNAP"
Sulfonamides > Nocardia (TMP-SMX)
Actinomyces > Penicillin
145
What stain for acid-fast bacteria is cheaper + more sensitive for screening than Ziehl Neelsen?
Auramine-Rhodamine
146
What are the 3 aerobic bacteria to remember?
picture the bellows from sketchy
Nocardia
Pseudomonas
MycoBacterium
"Nagging Pests Must Breathe"
147
What are the urease positive microbes?
for the mnemonic, think of what happens when you have struvite stones
Pee CHUNKSS
```
Proteus
CRYPTOCOCCUS (1 fungi!)
H pylori
Ureaplasma
Nocardia
Klebs
S epidermidis + S saprophyticus
```
148
Catalase+ organisms (10)
CATS Need PLACESS to Belch Hairballs
```
Pseudomonas
Listeria
Aspergillus (fungi!)
Candida (fungi!)
E coli
Staph
Serratia
Burkholderia cepacia
H pylori
```
picture the cats in sketchy; degrades H202 to water and O2 BUBBLES
149
Aside from the orofacial abscesses w/ sinus tracts...
what kind of infection can Actinomyces cause?
can cause infections in pts with IUDs leading to PID
tx with penicillin
(remember yellow "sulfur granules")
150
What microbe can mimic TB infection in immunocompromised pts? Differential?
Nocardia > cavitary lung lesions
will be negative on skin PPD test
151
cell wall mutation conveying resistance to vancomycin
D-Ala becomes D-LACTATE in vanc-resistant microbes
152
What is TRANSFORMATION in bacterial genetics?
Which bacteria do it, mostly? What can prevent it?
a bacterium BINDS + IMPORTS short pieces of naked bacterial chromosomal DNA (from other lysed bacteria) and then expresses its genes
SHiN bacteria (S pneumo, H. flu, Neisseria)
DNase degrades naked DNA + prevents
153
What type of CONJUGATION in bacterial genetics results in NO transfer of CHROMOSOMAL DNA?
what is transferred and how?
F+ x F- conjugation
F+ plasmid with genes for SEX PILUS allows an "F+" bacterium connect to an "F-" bacterium without the plasmid
a SINGLE STRAND of the double-stranded plasmid is transferred across the "mating/conjugal bridge" + then made double-stranded
(no transfer of chromosomal DNA)
154
What type of CONJUGATION in bacterial genetics results in transfer of some CHROMOSOMAL DNA?
what is transferred and how?
Hfr x F-
- F+ plasmid incorporates into the DNA of the F+ cell forming an "Hfr" (high-freq recombination) cell
- plasmid DNA plus a few flanking chromosomal genes are then transferred from the Hfr cell to an F- cell
- previously F- cell is still considered F- bc doesn't have a plasmid, but now has RECOMBINANT dna containing plasmid genes
155
What is TRANSDUCTION in bacterial genetics?
transfer of genes via a phage
156
What is GENERALIZED TRANSDUCTION in phage transfer of bacterial DNA?
via what type of phage?
a "packaging error" via LYTIC phages
phage infects bacterium > cleaves its DNA > new phage capsids are produced in infected bacterium (some contain phage DNA, some bacterial DNA) > phages are released > phage with bacterial DNA infects new bacterium and transfers old bacterium's genes to it
157
What is SPECIALIZED TRANSDUCTION in phage transfer of bacterial DNA?
via what type of phage?
an "excision" event via LYSOGENIC phages
1. lysogenic phage infects bacterium and INCORPORATES DNA into bacterial chrom.
2. phage DNA is EXCISED WITH FLANKING BACTERIAL GENES
3. new phage capsids can infect other bacteria with PHAGE/BACTERIAL DNA COMBO
158
what 5 BACTERIAL TOXIN genes are transferred via LYSOGENIC PHAGES?
ABCD'S
```
group A strep ERYTHROGENIC toxin
Botulinum toxin
Cholera toxin
Diphtheria toxin
Shiga toxin
```
159
what sterilization method is used to kill spores?
autoclave at 121 C for 15 minutes
160
what molecule does the core of a bacterial spore contain?
dipicolinic acid
161
What is TRANSPOSITION in bacterial genetics?
what bacterial process does this play a major role in?
a segment of DNA called a TRANSPOSON that can jump from one location to another (from plasmid to chromosome + vice versa)
role in plasmid-mediated transfer of MULTIPLE-ABX RESISTANCE GENES btwn bacteria
ex: Tn1546 carrying vanA gene from VRE to S. aureus
162
what kind of lymphocytes are the atypical lymphocytes in EBV?
T-lymphocytes
specifically CD8+
163
Coccidioides immitis
morphology
thick-walled spherules with endospores
much LARGER than RBC
(don't confuse the thick walls for the capsule of Cryptococcus! look for the endospores)
164
Coccidioides immitis
where? causes what?
SW united states
transient pulmonary sx in normal pts
progress SKIN, BONE and MENINGES in immunocompromised; "desert rheumatism" ARTHRALGIAS
can cause ERYTHEMA NODOSUM or MULTIFORME
165
Blastomyces dermatitidis
morphology
broad-based budding
SAME size as RBC
166
Blastomyces dermatitidis
s/s
lung disease can disseminate to...
SKIN / BONE
VERRUCOUS skin lesions look like SCC
forms GRANULOMATOUS nodules
167
special medium for Neisseria gonorrhoeae
its contents and what they inhibit (4)
Thayer Martin - chocolate sheep blood agar with...
1. Vancomycin - gram+
2. Colistin - gram-
3. Trimethoprim - gram-
4. Nystatin - yeast
(VCTN "vacation" from contaminating microbes)
168
Malarial form that is initially transferred by mosquito?
Sporozoite
goes to liver and forms a schizont of merozoites
169
Dormant liver malarial form?
Hypnozoite
170
Malarial structure containing many merozoites?
In what two places do they form?
SCHIZONTS are round collections of merozoites that form in the LIVER and RBCs and rupture to infect more RBCs
(liver schizonts are mefloquine resistant due to mefloquine inactivation in liver; RBC schizonts are killed by mefloquine)
171
Form of malaria that is released into circulation and infects RBCs
Merozoite
172
Which fungi form "SPORANGIA"?
Mold fungi such as RHIZOPUS
173
Aside from being round/oval cells with a noticeable polysaccharide capsule...
what is a characteristic of Cryptococcus microscopy?
NARROW-based BUDDING
| opposed to broad-based in Blasto
174
What prevents SUPERFICIAL Candida infection vs. HEMATOGENOUS spread of Candida?
superficial - T-CELLS ... so more superficial infections in HIV or similar immune disorder
hematogenous - NEUTROPHILS ... so more fungemia/endocarditis in pts with neutropenia (eg, leukemia pt)
175
Whipple disease
microbe, microbial characteristics
Tropheryma whippelii
intracellular Gram+ rods (actinomycetes)
176
Whipple disease
s/s
Older white male with...
C - Cardiac sx
A - Arthralgias - multiple joints
N - Neurologic sx - incl. psychiatric
Diarrhea/steatorrhea later
(FOAMY WHIPPed cream CAN; macros are foamy)
177
Whipple disease
histo (2 special features of affected cells)
SI mucosa with FOAMY macrophages that contain GRAM+ RODS and GRANULES that are...
1) PAS-positive
2) DIASTASE-resistant
(granules = lysosomes + partially digested microbes)
178
Tx of diphtheria (2 things)
1. Diphtheria antitoxin - preformed Ab
| 2. Abx - penicillin / erythromycin to decrease toxin formation
179
MCC of community acquired pneumonia
what about in HIV pts?
S. pneumo
SAME in HIV pts!
180
HPV strains for skin warts (verruca vulgaris)
1-4
181
HPV strains for anogenital warts
6, 11
182
How do NEURAMINIDASE inhibitors affect viral function?
inhibit VIRION RELEASE
183
Abx tx of Salmonella enterica causes what?
prolonged fecal excretion of the organism
184
What is a TYPE III SECRETION SYSTEM?
which microbes have it?
"injectisome"
needle like protein appendage that facilitates direct delivery of toxins from certain GRAM-NEG microbes
PESS - Pseudomonas, E coli, Shigella, Salmonella
185
Mechanism of Staph Scalded Skin Syndrome
epidermolytic exotoxins "EXFOLIATIN A + B"
cleave desmoglein-1 > similar sx to pemph vulgaris
(one is chromosomally encoded, other is plasmid)
186
Possible CV consequence of croup?
Pulsus paradoxus secondary to severe upper airway obstruction
187
Action of hemagglutinin
binds sialic acid and promotes viral ENTRY
188
surface molecule in ALL paramyxoviruses + its function
F (fusion) protein
causes resp. epithelial cells to fuse and form multinucleated giant cells
189
Enterococcal endocarditis
in whom? how?
OLDER MEN after CYSTOSCOPY
can also be by colonoscopy, or obstetrics procedures
190
Enterococci
main types of infections (4)
1. UTI
2. Endocarditis - after cystoscopy in old man
3. Intraabdominal
4. Pelvic
5. Wound
191
What is viral recombination?
What kind of viruses can do it?
NON-SEGMENTED dsDNA viruses (eg, HSV)
exchange of genes by CROSSOVER within homologous regions
progeny AND ALL SUBSEQUENT progeny will have recombined genomes w/ traits from both parents
192
What is phenotypic mixing in viruses?
when viruses co-infecting a cell exchange NUCLEOCAPSID / ENVELOPE proteins only
immediate progeny will have different outer surface proteins, but subsequent progeny will not because no genomic change
193
what's transformation in VIROLOGY (not bacterial genetics)?
incorporation of viral DNA into host chromosome ("lysogeny")
194
What microbe enhances Staph aureus hemolysis?
How?
Strep agalactiae
CAMP factor - a phospholipase that enhances beta-hemolysins
195
Disseminated gonococcal infection
triad
1. Polyarthralgia - moves around, resolving spontaneously in one joint and then appearing in others
2. TenoSynovitis - tenderness along tendons
3. Dermatitis - PAINLESS PUSTULES on limbs
(remember it's a triad but it's PTSD = Polyarthralgia (or purulent arthritis), TenoSynovitis and Dermatitis)
