Microbiology - Exam 2 Flashcards
Respiratory Microbes GI Microbes
Escherichia coli on MAC (MacConkey agar)
flat, pink colonies
E. coli on Xylose Lysine Deoxycholate agar (XLD agar)
yellow
E. coli on Hektoen Enteric (HE) Agar
orange
E. Coli on BAP
positive
E. coli on Bile Esculin Agar (BEA)
negative
Enterobacter sp. on MAC (MacConkey agar)
mucoid, pink colonies
Enterobacter sp. on Xylose Lysine Deoxycholate (XLD agar)
yellow
Enterobacter sp. on Hektoen Enteric (HE) Agar
orange
Enterobacter sp. on BAP
positive
Enterobacter sp. on Bile Esculin Agar (BEA)
negative
Enterococcus sp. on Bile Esculin Agar (BEA)
positive showing black agar
Lactose positive on MAC (MacConkey agar)
pink
Lactose negative on MAC (MacConkey agar)
clear
Lactose positive on Xylose Lysine Deoxycholate agar (XLD agar)
yellow
Lactose negative on Xylose Lysine Deoxycholate agar (XLD agar)
red
Lactose positive on Hektoen Enteric (HE) Agar
orange
Lactose negative on Hektoen Enteric (HE) Agar
green
What organism causes symptoms that are sometimes confused with those of appendicitis?
Yersinia enterocolitica
Which of the following is not true of Clostridium difficile?
A. It is a common pathogen following prolonged antibiotic therapy
B. Toxin B agglutination is the test for C. diff
C. It is an opportunist and part of the normal GI flora
D. It can cause pseudomembranous colitis and perforate the bowel if it reaches high numbers
B. Is false Clostridium difficile produces two toxins that cause the colitis….Toxin A and Toxin B. We have an agglutination (clumping) test to detect Toxin A.
Which form of E. coli produces chronic diarrhea due to inflammation of the colon, but it doesn’t invade the mucosa?
Enteroaggregative E. coli
What organism is thought to be a possible cause of Guillain-Barre syndrome?
Campylobacter jejuni
What bacteria can cause HUS (Hemolytic Uremic Syndrome?)
E. coli 0157-H7
What organism is associated with food poisoning from meat, processed meat (such as cold cuts) and milk?
Listeria monocytogenes – need to re-heat all meat that has been refrigerated, as Listeria can survive freezing temperatures.
What GI pathogen can cause death by flaccid paralysis?
Clostridium botulism
What is the most common species of Salmonella?
Salmonella typhimurium
This organism produces toxins causing watery diarrhea and a huge loss of electrolytes. It is known as “Traveler’s Diarrhea.” What is it?
Enterotoxogenic E. coli
What bacteria can cause pseudomembranous colitis?
Clostridium difficile
Which of the following is false concerning Vibrio cholera?
Very short incubation period Causes small amount of fluid loss in diarrhea Associated with water Transmitted via fecal-oral contamination No vaccine is available
B & E are falseB. Cholera causes huge fluid loss due to enterotoxin produced by the bacteria that causes salt (electrolytes) and water to be secreted from infected cells. Death can occur within 6 hours. E. The World Health Organization is involved in monitoring cholera epidemics. Vaccine is required for travel to some countries. The vaccine is only 50% effective and only provides immunity for 6 months.
What bacterial organism causes illness that is treated with antitoxin to prevent further binding of the toxin?
Clostridium botulism
What organism is shed from the GI tract in the feces of animals?
Salmonella sp.
What organism is found as a pathogen in 80% of chickens?
Campylobacter jejuni
Which form of E. coli produces profuse, watery diarrhea?
Enteropathogenic E. coli
What two pathogenic organisms need very few numbers to infect?
Clostridium botulism
Shigella dysenteriae
Which 7 bacteria that we have studied are normal flora of the GI tract, but are opportunists and can become pathogenic if numbers increase sufficiently?
Bacteroides sp. Clostridium sp. E. coli (most strains) Enterobacter sp. Enterococcus sp. Proteus sp. Pseudomonas sp.
What is the 2nd most common cause of gastroenteritis?
Salmonella sp.
Which statements are not true regarding Staphylococcus aureus?
It is normal flora on the skin and a pathogen in the GI tract.
If ingested, symptoms of nausea, vomiting, cramping, and possibly diarrhea may appear in 8-12 hours.
It releases an enterotoxin in foods that are stored at > 68 degrees for 2 or more hours.
Meat, poultry, and foods containing eggs and milk are especially susceptible.
B is false. The symptoms listed will appear in 1-2 hours following ingestion of the organism in food.
What GI pathogens can cause bloody diarrhea in humans?
Campylobacter jejuni
E. coli 0157-H7
Salmonella typhi
Shigella dysenteriae
Exotoxins are produced by what type of organism?
Mostly Gram positive
Gram negative pathogens can produce what type of toxins?
Endotoxins
Which of the following statements is false concerning Shigella sp?
Shigella has hundreds of different species
Shigella sp. normally causes a frequent small volume of diarrhea
Associated with enclosed places such as prisons, daycares, nursing homes
Found in food and water, including vegetables and ice cubes
Causes 500,000 deaths worldwide per year
A. and E. are false. A. Shigella has only 4 species, including Shigella dysenteria, which causes severe diarrhea with blood and mucous. E. Shigella sp. causes 1.3 million deaths per year worldwide. There are 500,000 cases in the US per year.
Food poisoning can be caused by which five organisms we have studied?
Clostridium botulism Enterotoxogenic E. coli Listeria monocytogenes Shigella dysenteriae Staphylococcus aureus
What organism is a gram positive sphere that grows as pinpoint colonies on Bile Esculin agar, turning the agar black around the colonies?
Enterococcus faecalis
This organism is the number one cause of gastroenteritis in developed countries like the U.S.
Campylobacter sp
What organism causes hemorrhagic colitis and sometimes death, and is associated with undercooked hamburger?
E. coli 0157-H7
This pathogenic organism is found only in primates
Shigella sp.
Which of the following statements about Yersinia enterocolitica are false?
It has caused many plagues from fleas that infest rats
It is associated with pigs
It can be gotten from food and water (milk), animals and other humans
It causes gastroenteritis, acute diarrhea, and sometimes fever
It may need cold temperatures prior to incubation to grow
All statements are true concerning Yersinia enterocolitica.
Heliobacter pylori is a GI pathogen associated with what disease?
Gastric (stomach) ulcers
What is the best treatment for gastric ulcers caused by Heliobacter pylori?
Several weeks of antibiotics to kill the organism and Pepto- Bismol® to coat and sooth the stomach lining.
You might get food poisoning from what organism if you eat potato salad that has been sitting out on the picnic table in the hot sun for 2 hours?
Staphylococcus aureus
Which of the following statements is false concerning Enteropathogenic E. coli?
Causes profuse, watery diarrhea Does not produce shiga toxin Is self limiting Treatment is sterilization of the gut and reintroduction of new bacterial flora Affects adults more than children
E. Children are especially at risk for this illness. All other statements are true about Enteropathogenic E. coli.
This severe disease caused by a GI pathogen increases in incidence during flooding conditions. What is the disease commonly called and what is the pathogen?
Typhoid Fever
Salmonella typhi
Which form of E. coli produces blood and pus in the stool, and is common in developing countries?
Enteroinvasive E. coli
What is the most virulent species of Salmonella?
Salmonella typhi
What test can you do to tell E. coli normal flora from E. coli 0157-H7?
Culture on Sorbitol MacConkey Agar. The 0157-H7 strain will grow as colorless colonies, and the normal flora will grow as pink colonies.
Which of the following statements is false concerning Clostridium botulism?
It is an anaerobic organism that produces spores in aerobic conditions
It produces a very potent toxin and therefore takes very few numbers to infect
It causes flaccid paralysis
Symptoms can start 12-36 hours after consumption
It is associated with canned goods and food with higher pH
All the statements are true about Clostridium botulism
What is the Gram stain and morphology of Campylobacter sp?
Gram negative vibrio
What GI tract pathogenic bacteria can cause neurological birth defects?
Listeria monocytogenes
Name of the organism that causes Strept throat
Streptococcus pyogenes
Name of the organism that grows as pin-point, beta-hemolytic colonies on BAP and is inhibited by the bacitracin disk
Streptococcus pyogenes
Name of the agar that is used to inhibit the growth of respiratory normal flora
SXT blood agar
Name of the organism that causes pneumococcal pneumonia
Streptococcus pneumoniae
Name of the organism that can cause birth defects when babies are born vaginally to mothers infected with this organism
Streptococcus agalactiae (or Group B Strept)
Name of the agar based test used to identify Group B Strept
CAMP
Name of the organism that causes pneumonia and grows as pink, mucoid colonies on MacConkey agar
Klebsiella pneumoniae
Mucus secreted from the lower respiratory tract
sputum
Name of the organism that causes bronchitis, does not grow on BAP, grows on CAP with increased carbon dioxide, and requires both X and V factor
Hemophilus influenzae
Name of the organism that does not grow on BAP, grows on CAP with increased carbon dioxide, and requires V factor
Hemophilus parainfluenzae
Name of the agar that contains factor X and factor V
Chocolate agar
Name of the technique used to differentiate H. influenzae from H. parainfluenzae
satelliting
Species of Hemophilus that grows between the V and X disk
H. influenzae
Species of Hemophilus that grows around the V disk
H. parainfluenzae
Name of organism that causes respiratory disease,is cultured on Lowenstein Jensen agar, and stains acid fast
Mycobacterium tuberculosis
Name of organism that has a cracker crumb appearance when cultured on Lowenstein Jensen agar
Mycobacterium tuberculosis
Name of organism known as the acid fast bacillus (AFB)
Mycobacterium tuberculosis
Name of the test used to determine if someone has antibody against Mycobacterium
PPD (purified protein derivative)
Length of time needed for Mycobacterium to grow on Lowenstein Jensen agar
28 days
Name of the weekly Gram negative bacteria that was first discovered in the 1970s at a convention in Philadelphia
Legionella pneumophilia
Type of staining method that the acid fast stain is
differential
Name of the chemicals used in the acid fast staining method
Kinynen carbofuchsin, acid alcohol, and methylene blue
The number of individuals affected by a disease in a given period of time in relation to the total population
morbidity (rate)
The number of deaths resulting from a disease in a given period of time in relation to the total population
mortality (rate)
This acts as the acid base indicator in the methyl red test; we add this after bacteria have grown in an MRVP broth (contains dextrose)
Methyl Red Test
Brom Thymol Blue acts as the acid base indicator in this test
Citrate Test
Phenol Red acts as the acid base indicator in this test that helps distinguish Proteus from Salmonella
Urea Agar
- Phenol Red acts as the acid base indicator in this agar
- Contains lactose and sucrose in slant, glucose in butt, as well as iron throughout the agar
TSI (Triple Sugar Iron) Agar
Grow bacteria in Tryptone broth and add Kovac’s reagent for this test
Indol Test
Reagent added to tryptone broth in the Indol test
Kovac’s reagent
