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GI- Microbiology
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75
Microbiology
Professional
01/20/2011

Additional Microbiology Flashcards

 


 

Cards

Term
How can infection cause anemia?
Definition
bacterial infections suppress erythropoietin production and the proliferation of erythroid progenitors; and also chronic infections impair iron utilization
Term
Lab results for Iron in anemia of chronic disease
Definition
low sFe, reduced TIBC, and abundant stored Iron in tissue macrophages
Term
Cause of pure red cell aplasia
Definition
B19 virus
Term

Infections that lead to aplastic anemia

(4 viruses)

Definition
hepatitis virus, CMV, EMV, and HSV
Term

Infections that lead to hemolytic anemia

(2 parasites)

Definition

Bebesia leads to cell lysis

Leishmania causes production of oxidative metabolic products that lyse RBCs

Term
Bacterial toxins that might cause toxin production
Definition

- alpha toxin in Clostridium perfringens

- Capsular polysaccharide (PRP) of hameophilus influenza type B binds red cell surface and anti-PRP antibodies lyse the cell

Term
Parasitic infection which causes microcytic anemia
Definition
iron deficiency anemia, associated with Hook Worm
Term
Infections that lead to megaloblastic anemia
Definition
B12 deficiency accompanying D. Latum infection
Term

B19 presentation in various hosts

(child, adult, chronic hemolytic anemia, immunocompromised patient, fetus)

Definition

fifth's disease

polyarthropathy

transient aplastic crisis (TAC)

PRCA Pure red cell aplasia

congenital anemia, hydrops fetalis

Term

B19 virus and anemia

(target  cell, presentation)

Definition

erythroid progenitor cells and erythroblasts, blood group antigen P

erythema infectiosum, arthalgia, arthritis

Term
What is transient aplastic crisis, what is the presentation and what infection is it associated with?
Definition

TAC is the abrupt cessation of erythropoiesis

reticulocytopenia, absent erthyroid precursors in the bone marrow and precipitous worsening of anemia

B19 associated TAC is found in patients with underlying hemolytic disorders or in patients with high RBC turnover

Term
If a pregnant woman in her second trimester is exposed to parvovirus B19, what thest should be done first?
Definition
obtain IgG and IgM serology ASAP
Term

What would each of the possible serology results of pregnant woman in her second trimester indicate/

- positive IgG result and negative IgM

- positive IgG and IgM

- negative IgG and positive IgM

- negative IgG and negative IgM

Definition

- indicates past infection (no risk to fetus)

- indicates infection with in the last 1-120 days (possible risk to fetus)

- indicates acute infection (higher risk to fetus)

- indicates the mother is not immune and that no evidence of acute infection is noted.  Repeat the test in three weeks.

Term

Treatments for the following anemias:

- pure red cell aplasia

- aplastic crisis

- HIV

Definition

- intravenous immunoglobulin (IVIG)

- packed RBCs

- HAART

Term
Two target cells of Malaria parasites leading to anemia
Definition

P.vivax binds Duffy blood group antigen

P. falciparum binds to sialic acid residues on glycophorin A

Term

Babesia microti

(transmission, population, acute and chronic presentation)

Definition

tick-transmitted protozoan

immunocompromised

inclusions- tends to form ring froms in tetrads

acute- malaise, headache, chills, sweating, periodic fatigue

chronic- hemolytic anemia, renal failure

Term
Symptoms of Hook Worm infrection
Definition

often asymptomatic

iron (microcytic) deficiency anemia

respiratory symptoms, itch, edema

Term

D. Latum

(associated anemia, other symptoms, diagnosis)

Definition

B12 deficiency leading to megaloblastic anemia

salt craving, intermittent abdominal discomfort

detection of large operculated eggs in stool or recovery of proglottids

Term

Bartonella bacilliformis

(Gram stain, different disease presentations)

Definition

gram-negative rods that penetrate RBCs

carrion disease- acute febrile illness

oroya fever- severe anemia

verruga peruana- blood-filled nodules

Term
5 common features of H. pylori and C. jejuni
Definition

- spiral or curved shape

- gram negative rods

- low G-C bqase ratio

- inability to ferment or to oxidize carbohydrates

- microaerophilic

Term

H. pylori

(urease, H2S production, nitrate reduction, growth at 42 C, shape, size)

Definition

positive

negative

negative

negative

spiral with 3 unipolar flagella

1 x 4 um

Term

C. jejuni

(urease, H2S production, nitrate reduction, growth at 42 C, shape, size)

Definition

negative

positive

positive

positive

bipolar flagella

not very wide

Term
Describe the symptoms associated with a C. jejuni infection
Definition

up to 10 stools/day

bloody diarrhea

RUQ pain- often only symptom

Term
Describe the symptoms of a C. fetus infection
Definition

endocarditis, septic thrombophlebitis

arthritis spetic abortion, meningoencephalitis, spontaneous peritonitis

Term
hyatid cysts in the liver
Definition
Echinococcus granulosus
Term
biliary obstruction
Definition
Ascaris lumbricoides
Term
Treatment of Campylobacter Infections
Definition

fluid and electrolyte replacemnet

empirical antibiotics for patients with high fever or bloody or frequent diarrhea

erthromycin clears in 72 hours

Term
Virulent factor of H. pylori
Definition
O-side chain resembles the blood group antigens so serve to protect the bacteria from immune clearance
Term
selequae of h. pylori
Definition
gastric ulcers, MALT (mucus associated tissue lymphoma)
Term
treatment for H. pylori
Definition

PPI

clarithromycin

beta-lactams

Term
bacteria found in scondary periotinitis caused by appendicitis perforation
Definition
Prevotella melaninogenica
Term
Most important cause of endemic severe diarrheal illness
Definition
Rotavirus group A
Term

Rotavirus

(S/Sx, D, T)

Definition

over a week duration

ELISA/Latex agglutination in stool samples

severe if ass. w/ dehydration and electrolyte imbalance

vaccines are available

Term
Explain the role of the NSP4 protein in rotavirus in causing diarrhea
Definition

intracellular release of Ca leading to diarrhea

disrupts tight junction allowing for paracellular flow of H2O and electrolytes

sitmulates the ENS

Term
Name three virulence factors of adenovirus
Definition

inhibition of MHC I expression

E proteins- block apoptosis by binding Rb and p53

VA-RNAS block interferon anti-viral response

Term
General characteristics of Enterobacteriaceae
Definition

Gram-negative rods

motile and facultative anaerobes

LPS is the major cell wall antigen

Term
Distinguish between typhoid and non-typhoid serovars of Salmonella
Definition

typhoid serovars: human-to-human, fecal-oral

non-typhoid: animal or contaminated food handling

Term
Summarize virulence factors employed by Salmonella to establish infection
Definition

attachment to epithelial cells by fimbriae; invade through M cells and enterocytes

replication occurs in the endocytic vacuole; disseminated infection can occur

enterotoxin produced

Term
Define  MacConkey Media
Definition

bile salts and crystal violet inhibit gram-positive

fermentation of lactose produces pink

Term
Describe EMB Media
Definition

Eosin blue and methylene blue inhibit the growth of gram positives

blue or green with lactose fermentation

Term
Discuss the mechanism by which Shigella invades intestinal epithelial cells
Definition

invades M cells of the colon by type III secretion

invades neighbor cells by comet-like actin tail

IL-1 release and PMN migration causes further loss in cell integrity

 

Term
Define the mechanism of action of Shiga toxin
Definition

AB subunit is cleaved by the protease furin

the A subunit inhibits protein translation by cleaving 28S rRNA

this causes cellular damage to intestinal epithelium

Term

ETEC

(site of action, disease, pathogenesis & virulence factors)

Definition

small intestine

Traveler's diarrhea

enterotoxins stimulate hypersecretions of fluids and electrolytes, colonization factor antigens

Term

EHEC

(site of action, disease, pathogenesis & virulence factors)

Definition

large intestine

hemolytic-uremic syndrome

shiga toxin disrupts protein synthesis. A/E lesions on microvilli results in decreased absorption. Bfp, intimin adhesion

Term

EIEC

(site of action, disease, pathogenesis & virulence factors)

Definition

diarrhea which progresses to dysentery with bloody stools

invasion mediated by invasive plasmid antigen

Term
Explain how SMAC media aids in the diagnosis of E.Coli.
Definition
E. coli O157:H7 (EHEC) is the only E.coli strain that does not ferment sorbitol
Term
What is the cause of Hemolytic Uremic Syndrome?
Definition
Shiga toxin form EHEC damages kidneys which release erythropoietin
Term

Yersininae enterocolitica

(general characterisitics, source, CF, Labs)

Definition

gram - rod, intracellular, cold tolerant

contaminated meat

gastroenteritis involving distal ileum, colon, and mesenteric lymph nodes, possible sequelae of autoimmune disorder

lactose negative, urease negative, motility at cold temperatures

Term

 

After three days of vacationing in the city of Lima, Peru, a newly married couple fall ill with what appears to be the same condition. Both experience vomiting, watery diarrhea, nausea, and abdominal cramps.  An analysis of their stool results in the isolation of gram-negative rods which produce colonies on MacConkey that are pink Which of the following is the most likely causative microorganism?

Definition
E. coli (is a lactose fermenter)
Term
A 28-year-old woman complains of painful swelling of the right knee and and tender skin eruptions on both shins.  For the past two weeks she has also had watery diarrhea that developed after she consumed some raw pork.  She also complains of low-grade fever and mild abdominal pain. Both red and white blood cells were observed in her stool sample. A stool sample revealed a gram-negative rod that was only motile at temperatures below 30°C. Clear colonies on MacConkey agar
Definition
Yersiniae enterocolitica ( motility below 30 C)
Term
A 16-year-old boy is brought to the emergency room by his parents, as he has been experiencing bloody diarrhea for 1 week.  He also complains of not urinating often and blood in his urine when he does.  His laboratory studies demonstrate an increased BUN and creatinine and the presence of gram-negative rods which produce beige colonies on SMAC and colonies on EMB as shown below (green).  The condition is associated with infection by which of the following E. coli types?
Definition
EHEC (beige on SMAC)
Term
A 36-year-old man comes to the emergency room because of the development of sudden nausea, vomiting, and diarrhea with blood and mucus, as well as crampy abdominal pain. He had just returned yesterday from a business trip to South America and has been experiencing these symptoms for two days. Leukocytes were found in his stools as well as a gram-negative non-motile rod.  Growth on MacConkey media after 48 hours shows clear colonies.  Which of the following is the most likely causative microorganism?
Definition
Shigella dysenteriae (non-motile, non-lactose fermenter)
Term
A 3-year-old man presents with sudden-onset, crampy abdominal pain and diarrhea.  The diarrhea is watery and contains mucus.  The patient also complains of low-grade fever with chills, malaise, nausea, and vomiting.  Careful history reveals that he had ingested partially cooked eggs at a poultry farm 24 hours before his symptoms began.  Based on this limited information, which of the following microorganism would you most likely suspect?
Definition
Salmonella enterica (sudden, mucus, poultry)
Term
A 3-month-old female infant was brought to the emergency department of a general hospital with a 5-day history of decreased activity, decreased oral intake, upper airway congestion, and general irritability. There was no history of fever or vomiting. During the previous 2 weeks, she had been constipated, and twice her mother had given a tablespoon of honey for treatment. The physical examination revealed dry oral mucosa, a sluggish pupillary response, and significant hypotonia. A gram stain of the fecal sample revealed a gram positive spore forming rod. Which of the following is the most likely diagnosis?
Definition
C. Botulism (flaccid paralysis)
Term
A 67-year-old man presented with fever, abdominal cramping, and frequent diarrhea for four days.  Three weeks before the current episode, he had undergone a hip replacement and was rehabilitating in an orthopedic unit.  During the hospitalization, he developed a nosocomial pneumonia and was treated empirically with clindamycin.  He gradually improved and was discharged a week before his current presentation, with maintenance oral antibiotics.  Which of the following is the most likely diagnosis?
Definition
Shigella sonnei (nosocomial infection)
Term

C. difficile

(CF, and A and B toxins)

Definition

pseudomembranous colitis

A- enterotoxin--> recruits PMNs

B- causes cytoskeletal damage

Term

C. perfringens

(LF and A and B toxins)

Definition

lechtinase enzyme destoys cells

causes precipitate growth on egg yolk agar

A enterotoxin disrupts ion transport

B enterotoxin forms pores--> bloody diarrhea

Term

C. botulism

(CF, source)

Definition

1-3 days of weakness, blurred vision, and constipation

flaccid paralysis

canned foods

Term
Specifics about two forms of Bacillus Cereus
Definition

emetic and diarrheal form

diarrheal form lasts longer, from meat and is heat labile

Term

Giardia lambia

(transmission, symptoms, E, D)

Definition

fecal-oral

diarrhea, increased fat and mucus in stool

worldwide, primarily human-to-human transmission

cysts (stain with Trichrome stain)and smiley-face trophozoite (stain with Kohn and Giemsa stain) forms are detected in feces

Term
What stain is diagnostic for Cryptosporium?
Definition
acid-fast stain, it won't stain with trichrome
Term
What is the treatment for cryptosporidium infection?
Definition
hydration, no drugs  are effective against crypto
Term

Cryptosporidium

(Et, Sx, E, D) 

Definition

fecal-oral

frothy BMs, anorexia, self-limiting, immunocompromised pateints cannot self cure

oocysts, acid fast stain

Term

Balantidium coli

(E, Sx, E, D)

Definition

fecal-oral

intermittent diarrhea with blood and pus, ulceration

worldwide, swine #1 animal reservoir

microscopic exam, bean-shaped macronucleus

Term
How does the O/P of E. histolytica read?
Definition
trichrome stain shows ingested red blood cells
Term

E. histolytica

(Et, Sx, E, D)

Definition

fecal-oral

dysentery, RUQ

worldwide, human-to-human

microscpic exam, motile trophozites

PCR differentiate histolytica from dispar

Term
O/P of Ascaris lumbricoides
Definition
large, mamillated coat and tapered end in fertilized egg
Term
O/P of stengyloides stercoralis
Definition
muscular neck, distinguished from hookworm by mouth at one end and notched tail on the other
Term
O/P of schistosoma mansoni
Definition
large spine projecting out of one side
Term
Life cycle of ascaris lubricoides
Definition

ingested eggs travel to the lunges

larvae break free

in 3 weeks larvae pass and can be swallowed back into the small intestine

Term
O/P of trichus trichiura
Definition
white worm , barrel shaped eggs with mucoid plugs at both ends
Term

Trichuris trichiura

(Et, Sx, E, D)

Definition

fecal-oral

diarrhea, rectal prolapse in children

Worldwide

concentrated microscopic specimen

Term

Schistosoma mansoni

(Et, Sx, E, D)

Definition

skin penetration by cercariae from snails

dermatitis, enlarged liver and lymph nodes, eosinophilia and dysentery

South America and Africa

schistosome eggs in stool and urine

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