Microbiology Flashcards
(110 cards)
1
Q
Most common inflammatory diarrhea in US?
A
- Campylobacter jejuni
- Salmonella
- Shigella
- Shiga toxin E coli (food borne outbreaks) not as common
2
Q
Severe vomiting and watery diarrhea after a meal 4 hours ago?
A
Staph Aureus
-lasts 24 hours
3
Q
S. Aureus Enterotoxin?
A
- Enterotoxin A
- Superantigen binds MHC to activate T cells and cytokines
- Stimulates vomiting center in breian
- Heat stable
- Only have to ingest toxin
4
Q
Bacillus cereus heat labile toxin MoA?
A
- spore forming Gram+ bacilli toxin that resembles heat labile toxin of E coli and V cholerae
- increase cAMP causing hypersecretion of water and electrolytes (diarrhea)
- ingest organism and toxin
5
Q
Vomiting after eating reheated rice?
A
ingestion of Bacillus cereus heat stable enterotoxin
-short incubation period and duration
6
Q
Diseases of Clostridium?
A
Anaerobic Gram+ spore forming bacillus
- Antibiotic diarrhea (C. difficile)
- Food poison (C. perfringens)
- Botulism (C. botulinum)
7
Q
Food poisoning from meat dishes like stew led to watery diarrhea and no vomiting or fever, 8-24 hours after the meal?
A
C. perfringens
8
Q
Illness from home canned foods, honey for infants, or wounds?
A
C. botulinum
9
Q
What type of environment does C. botulinum grow?
A
alkaline or neutral and anaerobic
10
Q
12-36 hours after meal, patient has blurry vision and descending B/L weakness of peripheral muscles that progresses to respiratory paralysis?
A
Neuro toxin of C. botulinum
-toxin irreversibly inhibits vesicle release of Ach at the synapse leading to flaccid paralysis
11
Q
Floppy baby syndrome?
A
consume food contaminated with botulinum spores usually in honey or infant formula
- colonizes GI
- constipation, lethargy, poor muscle tone
- look for toxin in stool
12
Q
Type of virus that causes gastroenteritis?
A
naked icosahedral viruses
13
Q
Clinical symptoms of viral gastroenteritis?
A
- incubation of few days
- abrupt onset watery diarrhea (adults): Norovirus
- vomiting (children): Rotavirus
- no blood in stool
- low grade fever
- dehydration (treat this)
14
Q
Leading cause of sporadic and outbreaks of diarrheal illness?
A
Norovirus
-naked icosahedral RNA calicivirus
15
Q
Person on cruise ship, presents with vomiting that precedes diarrhea that lasts for 12-60 hours?
A
Norovirus
-difficult to inactivate
16
Q
Cause of cholera?
A
toxigenic V. cholerae O1 and O139
17
Q
Vibriosis?
A
clinical disease not caused by V. cholerae O1 and O139
- coastal waters and sewage or raw shellfish
- Vibrio parahemolyticus from undercooked seafood
18
Q
After earthquake in Haiti, person presents with rice water stools (watery with flecks of mucous), dehydration and shock?
A
V. cholerae
- poor water sanitation
- if seen US, usually due to travel
19
Q
MoA of cholera toxin?
A
active subunit transported to adenylate cyclase to increase cAMP which decreases Na absorption and increases Cl secretion
20
Q
O157:H7 E. coli can cause what?
A
Hemolytic uremic syndrome from shiga toxin
- colonizes distal ileum and colon
- pathogen in livestock transmission by foodborne
21
Q
Patient who recently traveled presents with watery diarrhea and low grade fever that lasted about a week?
A
Enterotoxigenic E coli
- heat stable
- heat labile
22
Q
MoA of ETEC?
A
subunit transported to adenylate and guanylate cyclase to increase cAMP and cGMP to decrease absorption of Na and increase secretion of Cl
23
Q
Gram- that ferments lactose but not sorbitol?
A
O157 STEC
-non O157 ferments sorbitol
24
Q
MoA of shiga toxin?
A
cleaves 60s ribosome that prevents binding of tRNA to inhibit protein synthesis
25
Watery diarrhea that becomes bloody in a few days and severe abdominal pain, not a lot of fecal leukocytes?
STEC
26
Hemolytic uremic syndrome?
Renal failure
Thrombocytopenia
Hemolytic anemia
-from STEC
27
Watery diarrhea that becomes bloody, not in the US, and a lot of fecal leukocytes?
Enteroinvasive E. coli
| -shiga like
28
Infant with watery diarrhea in developing country?
Enteropathogenic E. coli
| -disrupts microvilli, non-inflammatory
29
Child with watery to mucoid diarrhea in developing country for longer than 2 weeks?
Enteroaggregative E. coli
| -attaches and forms biofilm that stimulates mucous
30
Person in US with watery diarrhea, culture shows nonmotile, non lactose fermenting. The diarrhea turns bloody in a few days. Diagnosis?
Shigella sonnei
| -enterotoxin: watery diarrhea
31
Pathophys of shigella?
internalized by enterocytes that can lead to abscesses, ulcers, and inflammation causing bloody diarrhea
32
Pathophys of salmonella?
adhesin causes ruffling of membrane then invades lamina propria of SI to induce inflammatory response
-some get into blood stream and produce systemic response
33
Watery diarrhea that becomes bloody 2 days after eating raw chicken and eggs?
Salmonella gastroenteritis (enteritidis)
34
Reservoir for enteric fever salmonella?
chronic infection of GB
| -mostly seen in travelers
35
Enteric fever pathophys?
S. typhi replicates within phagolysosome of macrophages to inhibit respiratory burst
- enters lymph to RES
- bacteremia
- take 2 weeks
36
Patient with fever, headache, slow pulse, and faint abdominal rash?
enteric fever from S. typhi
37
Bacteremia from S. typhi?
- reinfects GI causing later disease diarrhea
- can also infect bones, joints, liver, meninges, UTI
- hemorrhage from perforations through wall of terminal ileum and proximal colon
38
Enteric species of yersinia?
Y. enterocolitica
Y. pseudotuberculosis
-pigs are reservoir (undercooked pork)
39
Yersinia gastroenteritis pathophys?
- invasion of epithelial cells and impair PMN and macrophages to resist phagocytosis, disrupt actin, and induce apoptosis
- invades terminal ileum
- infects M cells of peyers patches
- inflammation of mesenteric LN
40
Patient with fever, diarrhea, RLQ pain, and mesenteric lymphadenitis?
Yersinia
41
Systemic yersinia?
- enteric fever
- polyarthritis
- intraabdominal abscesses
42
Inflammatory diarrhea from contaminated chicken in US in the summer, not an outbreak?
Campylobacter jejuni
| -curved gram- microaerophilic rod
43
Pathophys of campylobacter?
tissue damage to jejunum, ileum, and colon causing crypt abscesses and inflammation
44
Complication of campylobacter jejuni?
GBS
- acute demyelinating syndrome
- autoimmunity to LOS ganglioside core (myelin)
Reactive arthritis
45
Patient in hospital on antibiotics gets diarrhea?
C. difficile
- Abx disrupts microbiota leading to pseudomembranous colitis
- 5-10 days after Abx
46
C. difficile pathophys?
```
Toxin A (enterotoxin)
-disrupts intracellular junctions causing hyper secretion of fluids and inflammation
```
```
Toxin B (cytotoxin)
-depolymerization of actin causing loss of cytoskeleton
```
47
Most common Abx leading to C. difficile?
- Cephs
- Ampicillin
- Clindamycin
- Floroquinolones
48
Treatment of C. difficile?
Oral Vancomycin
-can get relapse if Abx resistance out compete normal flora
Fecal Transplant
-restore healthy microbiota
49
Diarrhea outbreak from cheese and ice cream?
Listeria monocytogenes
| -Gram+ rod, heat resistant and replicates at cold temps
50
Who is at risk for listeria?
Immunocompromised
- elderly
- pregnant women (stillborn)
51
Pregnant woman with diarrhea, muscle aches, stiff neck, and loss of balance?
Listeria
| -meningoencephalitis
52
Test for C. difficile?
EIA for glutamine dehydrogenase
53
Gram- curved rod with flagella and urease?
H. pylori
54
H. pylori pathophys?
- motility allows bacteria to get below mucous layer and urease produces ammonia which neutralizes acid
- VacA causes apoptosis and cell permeability
- Cag disrupts cell junctions and induces IL-8 (inflammation)
55
Most common cause of gastritis?
H. pylori
| -induces gastrin release to increase acid secretion causing ulcers, can perforate
56
H. pylori diagnosis?
Endoscopy
Urea breath test
Fecal antigen
57
Transmission of giardia?
- Fecal oral
| - sexually transmitted
58
What is the infective form of giardia?
- owl shaped parasite that infects as cyst
| - transforms into trophozoites as metabolically active form
59
Presentation of giardia?
- foul smelling, frothy stools
- steatorrhea
- on and off pattern of diarrhea
- ab pain
- belching
- post giardia lactose intolerance
60
Virulence factors of giardia?
- sucking disk
| - flagella
61
Pathophys of giardia in intestines?
- villous blunting
- crypt hyperplasia
- diminished brush border enzymes
- cell infiltration
62
Treatment of giardia?
Metronidazole
- tinidazole
- nitazoxanide
63
Carrier of giardia?
beavers
64
Cryptosporidium stain?
modified acid fast stain with oocysts (round and small)
65
AIDS patient with chronic diarrhea. Stain shows small and round cysts. Diagnosis?
Cryptosporidium
66
Source of cryptosporidium?
- sewage
- run off
- septic tank
- animal feces
- bird droppings in stored water
67
Kid who attended a school picnic where they picked apples gets diarrhea?
Cryptosporidium
68
Treatment of cryptosporidium?
Nitazoxanide
Antiretroviral therapy if AIDS patient
69
Difference between cyclosporine and cryptosporidium cysts?
Cyclo oocysts need a few days to mature whereas crypto is immediately infective
70
Outbreak of diarrhea associated with imported raspberries and strawberries from guatemala?
cyclosporidium
71
1. Traveler to nepal presents with watery diarrhea, severe fatigue, nausea, anorexia, and bloating?
2. Treatment?
1. cyclosporidium
| 2. TMP/SMX
72
Size of crypto vs cyclo?
Cyclo
- 8-10 um
- variable acid fast
- self limiting
Crypto
- 3-5um
- acid fast
- AIDS life threatening
73
1. AIDS patient with chronic diarrhea, eosinophilia, and charcot leyden crystals. Stain shows elliptical cysts. Diagnosis?
2. Treatment?
1. Cystoisospora belli
- contaminated food/water
- day care centers
2. TMP-SMX
74
What does cystoisospora look like?
elliptical oocysts
75
Entamoeba histolytic pathophys?
ingested as infective cyst, transforms to hematophagous trophozoite and lyses RBC
76
Hispanic boy with fever, dysentery, severe epigastric pain, anorexia, and liver abscesses. Aspirate obtained looks like anchovy sauce.
1. Diagnosis?
2. Treatment?
1. E. histolytica
| 2. Metronidazole and Iodoquinol
77
Why not use corticosteroids to treat amebiasis?
contraindicated due to acquisition of toxic megacolon
78
AIDS patient and IVDA presents with keratoconjunctivitis, brain lesions and spores in CSF? Treatment?
1. Cerebral Microsporidia
| 2. Abendazole
79
Microsporidia virulence factor?
polar tubule extrudes from spore and penetrates plasma membrane of host
80
Ciliated trophozoite?
Balantidium coli
81
Transmission of chagas disease?
kissing bug defecates while feeding
| -trypanosoma cruzi
82
Treatment of chagas?
Benzidazole
83
Complications of chagas?
- megaesophagus (achalasia)
- megacolon (constipation, ischemia)
- chronic: cardiomyopathy
- heart block
84
Patient with fever, hepatosplenomegaly, lymphocytosis, and closed and itchy eye?
chagas
85
Hook worms?
Necator americanus
Ancyclostoma duodenale
86
Pin worms?
Enterobius vermicularis
Trichinella spiralis
87
Whipworm?
Trichuris trichuria
88
Child with RLQ pain and Anal itching at night.
1. Diagnosis?
2. Pathophys?
3. Treatment?
1. Enterobius vermicularis (pinworm)
- lives in cecum
- not very serious
2. female worm migrates through anal canal to deposit eggs at night
3. Oral albendazole
89
Transmission of enterobius?
- fingernails autoinfection
| - soiled night clothes or linens
90
Patient with severe epigastric pain, low grade fever, and tingling throat after ingestion of raw or partially cooked fish. Diagnosis?
Anisakiasis (sushi worm)
| -secretory products pathogenesis
91
Pathophys of trichinella?
ingest wild game (pork) and larva migrate to striated muscle causing calcification
92
Patient who ate wild boar presents with fever, cough, B/L proptosis, myalgia, and watery diarrhea.
Diagnosis?
Treatment?
1. Trichinella spiralis
| 2. Albendazole
93
Patient on steroids develops E. coli and presents with abdominal rash extending to thighs, eosinophilia, fever, and hypotension.
1. Diagnosis?
2. Pathophys?
3. Treatment?
1. Strongyloides stercoralis disseminated
2. massive larvae migration through intradermal vessels and mesenteric veins
2. Oral Ivermectin and Albendazole
94
Hyperinfection syndrome of strongyloides?
- Bronchopneumonia
- gram negative sepsis
- meningitis
95
Patient with rectal prolapse?
```
Trichuris Trichuria (whip worm)
-lemon eggs
```
96
Patient with worsening pain in RUQ, cough, anorexia, and fatigue with worms seen in jejunum on CT?
Gastric Ascaris
| -fecal oral
97
Patient with decreasing central vision in right eye. Something wiggling is seen on fundoscopic exam. Diagnosis?
```
Necator americanus (Hookworm)
-penetrates skin
```
98
Patient with megaloblastic anemia and tapeworm?
Diphyllobathrum datum (fish)
99
Immigrant with new onset epilepsy and brain lesion.
1. Diagnosis?
2. Treatment?
1. Neurocysticercosis
- Taenia folium
2. PZQ and steroids
- antiparasitics exacerbate brain swelling
100
Gravid proglottid?
Taenia saginata
101
Patient with chronic cough, hyperpryexia, tachypnea, and ruptured hydatid cyst?
Echinococcus granulosus
102
AIDS patient with diarrhea and hunger after eating upon returning from trip to caribbean were she ate fish?
Diphylobothrium latum
| -associated with Vit B12 deficiency (megaloblastic anemia)
103
Patient from Ghana and Egypt has painless gross hematuria?
Schistosoma haematobium eggs with terminal spine
| -bilharzia
104
Hemoptysis after eating raw pickled crab?
Paragonimus wetermani
105
Patient with sudden swelling of right lower eyelid after eating raw reptile?
Subcutaneous sparganosis
106
How to eradicate dracunuculiasis?
water filers
107
Mass deworming treatment?
Albendazole
108
Treatment schistosomiasis?
PZQ
109
Treatment of river blindness?
Ivermectin
110
ADR of metronidazole?
- disulfaram like effect w/ alcohol
- peripheral neuropathy
- encephalopathy
