Micro 1 test 3
143. Biochemical reactions of an organism are consistent with Shigella. A suspension is tested in antiserum without resulting agglutination. However, after 15 minutes of boiling agglutination occurs in group D antisera. The Shigella species is:
sonnei
Gram's iodine reagent
starch hydrolysis
amylase enzyme
starch hydrolysis
The TSI media contains 3 sugars that include
sucrose,glucose,lactose
utilize TSI agar to detect the production of H2S.
the Hydrogen Sulfide Production using TSI agar test will
TSI agar is inoculated using
the inoculation needle to stab the butt of the agar slant and then streak the surface of the slant.
If only glucose is fermented the slant will initially turn yellow but will revert back to red because
the protein in the agar is broken down releasing alkaline products after all the glucose is used up.
why does the TSI agar contains the pH indicator phenol red ,
to allow detection of carbohydrate fermentation.
Escherichia coli characteristics
traveler's diarrhea; most common inhabitant of the GI tract; produces vitamin K ; can become opportunistic, causing UTIs, pyometra, peritonitis, or infections of wounds, hemorrhagic lesions, bloody diarrhea,
fatty acids product
triglyceride hydrolysis
lipase enzyme
triglyceride hydrolysis
spirit blue agar media
triglyceride hydrolysis
TSI is an acronym for
triple sugar iron agar
indole product
tryptophan degradation
A/ circled A
two or more sugars were fermented and gas produced (no H2S produced)
Salmonella typhi
typhoid fever
urease enzyme
urea hydrolysis
A suspension of organisms suspected to be Shigella based on biochemical reactions did not agglutinate with Shigella antisera subgroups A, B, C, and D. The tech would conclude that:
This particular Shigella possesses a capsular antigen that blocks agglutination in O antiserum and must first be destroyed by heating
To differentiate Proteus mirabilis and Proteus vulgaris this test is performed
Indole
D) Catalase - Staphylococcus aureus and Staphylococcus epidermidis
Indole - E. coli and Proteus mirabilis
Which of the following combinations of organisms would be appropriate as controls to test the functions listed?
Indole - E. coli and Proteus mirabilis
This organism is most probably Haemophilus:
Influenzae
153. Plesiomonas shigelloides is a relatively new member to the family of the Enterobacteriaceae. What characteristic separates it from other member of the Enterobacteriaceae?
It is oxidase positive. Enterobacteriaceae ferment glucose and are oxidase negative.
only glucose was fermented
K/A
no sugars were fermented
K/K
Name two test for reactions that produce acid end products...
KIA and fermentation of carbohydrates
What media can be used for this differentiation between Salmonella and Shigella from most of the other enterobacteria?
MAC, XLD, EMB
Which of the following medias is used to grow E. coli O157:H7?
MacConkey Sorbitol agar
Urine culture should be plated to:
MacConkey agar and Sheep blood
193. Appropriate culture requirement for a specimen from a patient suspected of having tularemia include:
Media with cysteine such as buffered charcoal yeast extract agar.
Fermentation of carbohydrates releases acid
which reacts with the pH indicator to change the color of the media from red (neutral pH) to yellow (acidic pH).
What is the correct indole test result for Proteus mirabilis?
Negative
Name a nonfermentative test in which gas production indicates a positive test result...
Nitrate reduction.
If two or more sugars are fermented both the butt (lower portion of the agar) and the slant (upper portion of the agar)
will appear yellow
When H2S is produced by bacteria it combines
with the iron in the media to form iron sulfide
141. Shigella species characteristically are:
Nonmotile; Shigella is also urease and oxidase negative and nonfermenters.
175. Which one of the following results is typical of Campylobacter jejuni?
Optimal growth at 42C.
Biochemical reactions of an organism are consistent with Shigella. A suspension is tested in polyvalent antiserum without resulting agglutination. However, after 15 minutes of boiling, agglutination occurs in polyvalent and group D antisera. This indicates that the:
Organism possesses capsular antigens
178. Haemophilus influenzae is most likely considered normal indigenous flora in the:
Oropharynx, the upper respiratory tract.
199. Differentiating tests that will separate Burkholderia from Stenotrophomonas include:
Oxidase; both are gram-negative and grow on MAC, neither ferment glucose. Stenotrophomonas is oxidase-positive while most nonfermenters are oxidase-positive.
A culture from an infected dog bite yields a gram negative, bipolar staining bacillus. The organism is cytochrome oxidase and indole test positive. The most likely identification of this isolate is:
Pasteurella multocida
Which of the following is the most likely organism?
Pasteurella multocida
Which of the following organisms is still susceptible to penicillin drugs?
Pasteurella multocida
185. Gram-negative bacillus with bipolar staining was isolated from a wound infection caused by a cat bite. The following characteristic reactions were seen: Oxidase-negative; glucose OF- fermentative, Catalase-positive, motility-negative, MAC- no growth. Which of the following is the most likely organism?
Pasteurella multocida.
What is the correct indole test result for E. coli?
Positive
What is the correct indole test result for Proteus vulgaris?
Positive
191. Which characteristic best differentiates Acinetobacter species from Moraxella species?
Production of indophenol oxidase. Both display resistance to penicillin, and some grow on MAC. Acinetobacter are oxidase-negative and Moraxella are oxidase-positive.
If present, a characteristic that is helpful in separating Pseudomonas aeruginosa from other members of the Pseudomonas family is:
Production of pyocyanin pigment
Which coliform bacteria are the most difficult to distinguish from the SS pathogens?
Proteus
What is the primary characteristic used to differentiate them?
Proteus is positive for urea and the other two are negative
The organism is most likely:
Proteus mirabilis
The organisms are most likely:
Proteus mirabilis and Serratia marcescens
What media can be used to differentiate between Salmonella and Shigella?
SIM media for motility and looks black if H2S production.
Twenty patients on a surgical ward develop urinary tract infections after catheterization. In each instance, the isolated organism grows on sheep blood agar as a large, gray colony, and on MacConkey agar as a large, flat, pink colony. The oxidase negative, gram negative rod produces the same biotype and is resistant only to tetracycline. Additional biochemical results are as follows:
...
Urea- Positive
...
UreaPositive
...
UreaPositiveNegative
...
Urease- Negative
...
Urease: negative
...
V factor requirement -Yes
...
VP- Positive
...
VPPositive
...
Which of the following bacteria has a red pigment on MacConkey agar?
...
Which of the following combinations of organisms would be appropriate as controls to test the functions listed?
...
X factor requirement -Yes
...
alpha-naphthol reagent
2,3-butanediol fermentation
MR-VP test medua
2,3-butanediol fermentation, mixed - acid fermintation
D) Pseudomonas aeruginosa
A) Serratia marcescens
Escherichia coli
A/circled A
179. Haemophilus influenzae becomes resistant to ampicillin when the organism produces a(n)"
Beta-lactamase enzyme
A gram negative rod has been isolated from feces, and the confirmed biochemical reactions fit those of Shigella. The organism does not agglutinate in Shigella antisera. What should be done next?
Boil the organism and retest with the antisera
142. A gram-negative bacillus has been isolated from feces, and the confirmed biochemical reactions fit those of Shigella. The organism doesn't agglutinate in Shigella antisera. What should be done next?
Boil the organism and retest with the antisera; some Shigella produce capsular antigen that mask cell wall and boiling removed the capsule.
181. Which of the following specimens is considered to be the most sensitive for the recovery of Brucella in cases of chronic infection?
Bone marrow, considered the most sensitive specimen.
Kligler's iron agar and SIM are multiple test media, What test do these media have in common?
Both test for cystein to hydrogen sulfide.
Which of the following is the normal reservoir for Vibrio cholera?
Brackish water
What types of gases can be produced as a result of sugar fermentation?
CO2
What difficulties does one encounter when trying to differentiate bacteria on the basis of physiological tests?
Contamination can give a false positive.
196. A lab aid receives a bronchoscopy sample with the request for culture of Legionella. The assistant asks the microbiologist for direction on plating protocol. The correct response from the microbiologist is:
Culture on buffered charcoal yeast extract agar with antibiotics.
190. Serum samples collected from a patient with pneumonia demonstrate a rising antibody titer to Legionella. A bronchoalveolar lavage (BAL) specimen from this patient had a positive antigen test for Legionella but no organisms were recovered on buffered charcoal yeast extract medium after 2 days of incubation. The best explanation is that the:
Culture was not incubated long enough, Legionella requires at least 7 days at 37-37C
Family characteristics of the Enterobacteriaceae include
Fermentation of glucose
Family characteristics of the Enterobacteriaceae include
Fermentation of glucose, gram neg rods, nitrates to nitrites, low oxygen, grow on mac
Both Kligler's iron agar and SIM are stabged but for different reasons, WHY?
For Kligler's it is to test for the fermentation of the sugars. For SIM it is to test for motility.
192. An organism has been identified as a member of the fluorescent group of Pseudomonas. Which of the following sets of tests should be used to determine the species of the organism?
Growth at 42C, procyanin production, gelatinase production.
173. If present, a characteristic in differentiating Pseudomonas aeruginosa from other members of the Pseudomonas family is:
Growth at 42C, this temp is inhibitory for other Pseudomonas.
Which of the following bacteria is associated with chancroid
Haemophilus ducreyi
168. A 4yr old boy is admitted to the hospital with suspected meningitis. He has not had most of the childhood vaccines. The suspected pathogen is:
Haemophilus influenzae, previously most common cause of bacterial meningitis in young children. Now there is a type B vaccine that has greatly reduced the H. influenzae incidence of meningitis.
160. An organism that exhibits the satellite phenomenon around colonies of staphylococci is:
Haemophilus influenzae, requires X and V factors. Sheep blood agar supplies X and staphylococci produce V, so colonies grow around staph.
163. A small gram-negative bacillus is isolated from an eye culture. It grows only on chocolate agar and is oxidase- negative. The most likely organism is:
Haemophilus influenzae.
172. A CSF has been inoculated onto sheep blood and chocolate agar plates and into a tube of trypticase soy broth. All media were incubated in an atmosphere of 5% CO2. Which of the following organisms would usually be isolated by this procedure?
Haemophilus influenzae.
The name given to rat-bite fever when the illness is acquired by ingestion of the bacterium is
Haverhill fever
What characteristic separates Salmonella and Shigella from most of the other enterobacteria?
Salmonella and Shigella do not ferment Lactose.
What two characteristics separate Salmonella from Shigella?
Salmonella are motile and produce hydrogen sulfide and Shigella are negative for both.
Kovac's reagent
Tryptophan degradation
2.3-butanediol product
Voges-Proskauer test
Vibrio parahaemolyticus can be isolated best from feces on:
Thiosulfate citrate bile salts (TCBS) agar
A patient is admitted to the hospital with symptoms of appendicitis. A stool specimen for culture reveals a gram negative bacillus that is oxidase negative, catalase positive, urease positive, and weakly fermentative. TSI shows yellow slant and yellow butt. These reactions suggest the possibility of:
Yersinia enterocolitica
This organism is most likely:
Yersinia enterocolitica
This organism most likely is:
Yersinia enterocolitica
Which of the following is the most appropriate organism for growth on cefsulodin-irgasan-novobiocin (CIN) agar
Yersinia enterocolitica
Which of the following is the most appropriate organism for growth on cefsulodin-irgasan-novobiocin (CIN) agar?
Yersinia enterocolitica
Enterobacter cloacae & Enterobacter aerogenes lab I.D.
lactose -, catalase +, indole -, oxidase - , motility - , citrate - , urease - , TSI: -/+; g; H2S -
Proteus mirabilis lab I.D.
lactose -, catalase +, indole -, oxidase -, motility +, citrate variable, urease +, TSI: -/+; g; H2S +
Yersinia pestis lab I.D.
lactose -, catalase +, indole -, oxidase -, motility -, citrate -, urease -, TSI: -/+; w/o g; H2S -
Production of H2S gas is a biochemical difference useful in identification of unknown organisms, especially
members of the Enterobacteriaceae family
Methyl red reagent
mixed-acid fermentation
Acceptable specimens for detection of Bordetella pertussis are
nasopharyngeal aspirates
dimethyl-alpha-naphthylamine reagent
nitrate reduction
sulfanilic acid reagent
nitrate reduction
Proteus vulgaris characteristics
not as often seen in labs, usually only targets immunosuppresed individuals , test + on indole test
N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride reagent
oxidase test
180. An isolate on chocolate agar from a patient with epiglottis was suggestive of Haemophilus species. Additional testing showed that the isolate required NAD for growth and was nonhemolytic. The organism is most likely Haemophilus:
parainfluenzae, require NAD for growth but not Hemin, this distinguishes it from H. influenzae.
ferric chloride reagent
phenylalanine deamination
phenylpyruvic acid product
phenylalanine deamination
ammonia product
phenylalanine deamination, tryptophan degradation, urea hydrolysis
Serratia characteristics
produces a characteristic red pigment, causes urinary & repiratory tract infections,bovine mastitis & other sporatic infections in animals , found in supposedly sterile solutions, can produce DNase, Lipase, Gelatinase
Salmonella causes...
salmonellosis
197. A community hospital micro lab is processing significant numbers of stool cultures because of an outbreak of diarrhea following heavy rains and flooding in the country. A media that should be incorporated in the plating protocol is:
Thiosulfate citrate bile salts sucrose for Vibrio species.
Why is it important to complete morphological and cultural characterizations before pursuing physiological testing?
This gets you started in the right direction and which test to use to determine your unknown.
CatalasePositive
...
Citrate- Negative
...
Citrate- Positive
...
Citrate: negative
...
CitratePositive
...
Gas produced
...
Oxidase- Negative
...
Glucose Fermentative
...
Glucose Positive
...
Glucose- Acid, gas produced
...
Glucose- Positive
...
OxidasePositive
...
GlucoseAcid, gas produced
...
GlucosePositivePositive
...
H2S
...
H2S- Positive
...
H2SPositive
...
H2SPositiveNegative
...
Hydrogen sulfide- Negative
...
Hydrogen sulfide: negative
...
Indole Negative
...
Indole- Negative
...
Indole- Positive
...
Indole: positive
...
Isolate 1Isolate 2
...
Lysine decarboxylase- Positive
...
Lysine decarboxylase: positive
...
MacConkey agarNo growth
...
Phenylalanine deaminase- Negative
...
Phenylalanine deaminase: Negative
...
Shigella dysenteriae
...
TDA- Positive
...
TDAPositive
...
TDAPositiveNegative
...
If gas is produced in the butt, visible as breaks or bubbles in the agar the
"A" for the butt is circled. /
Citrobacter freundii
(A/A + H2S)
Salmonella typhimurium
(K/A + H2S)
Providencia alcalifaciens
(K/A, but sometimes appears K/K)
If a black precipitate is present the slant/ butt
(ex. A/A) is followed by "+ H2S
A
(for acid
13. A sputum culture from an alcoholic seen in the ER grows gray, mucoid, stringy colonies on sheep blood. The isolate grows readily on MacConkey agar and forms mucoid, dark pink colonies. The colonies yield the following test results:
...
14. A urine culture had the following culture results:Sheep blood- Swarming, Sheep blood- Columbia CNA- No growthSwarming, MacConkey- 1. >100,000 CFU/mL nonlactose-fermenter,2. > 100,000 CFU/mL red, nonlactose fermenter
...
15. More than 100,000 CFU/mL of gram negative bacilli were isolated on MacConkey from a urine specimen. Biochemical results are as follows:
...
24. Twenty patients on a surgical ward develop urinary tract infections after catheterization. In each instance, the isolated organism grows on sheep blood agar as a large, gray colony, and on MacConkey agar as a large, flat, pink colony. The oxidase negative, gram negative rod produces the same biotype and is resistant only to tetracycline. Additional biochemical results are as follows:
...
> 100,000 CFU/mL red, nonlactose fermenter
...
A TSI tube inoculated with an organism gave the following reactions:
...
A febrile and pneumonic illness first named in 1976 by scientists at the Centers for Disease Control and Prevention (CDC) who were investigating an epidemic of pneumonia among Pennsylvania State American Legion members attending a convention in Philadelphia is known as
...
A gram negative rod was isolated from a wound infection caused by a bite from a pet cat. The following characteristic reactions were seen:
...
A small gram negative rod isolated from an eye culture has the following test results:
...
A sputum culture from an alcoholic seen in the ER grows gray, mucoid, stringy colonies on sheep blood. The isolate grows readily on MacConkey agar and forms mucoid, dark pink colonies. The colonies yield the following test results:
...
A) Indole - E. coli and Proteus mirabilis
...
A) Serratia marcescens
...
Acid butt
...
Acid slant
...
Acid slant,Acid butt,No H2S,No gas,This organism most likely is:
...
Alkaline slant
...
An organism is inoculated to a TSI tube and gave the following reactions:
...
An organism was inoculated into a TSI tube and gave the following reactions:
...
B) E. coli
...
B) Oxidase - Pseudomonas aeruginosa and Burkholderia cepacia
...
The isolates from MacConkey agar had the following biochemical reactions:
...
The most probable identity of this organism is:
...
More than 100,000 CFU/mL of gram negative bacilli were isolated on MacConkey from a urine specimen. Biochemical results are as follows:
...
MotilityNegative
...
No H2S
...
No gas
...
No gas produced
...
ONPG Positive
...
ONPG- Positive
...
Ornithine decarboxylase- Positive
...
Ornithine decarboxylase: positive
...
Oxidase Negative
...
C) Beta hemolysis - E. coli and Streptococcus pyogenes
...
C) Klebsiella oxytoca
...
165. The optimal incubator temperature for isolation of the Campylobacter jejuni/coli group is:
42C, at this temp other organism from colon are inhibited.
176. Optimum growth of Campylobacter jejuni is obtained on suitable media incubated at 42C in an atmosphere containing:
6% O2, 10-15% CO2, 85-90% Nitrogen
152. A clean catch urine specimen from a nursing home patient is cultured using a 0.001 mL loop. It grows 67 colonies of a lactose fermenter that has the following biochemical reactions: TSI- acid/acid; Oxidase- negative; Motility- positive; indole- negative; citrate- positive; VP- positive; Lysine decarboxylase- negative; Ornithine decarboxylase- positive; urea- negative. What should the microbiologist report?
67,000 CFU/mL Enterobacter cloacae.
Bacteremia, endocarditis, bacillary angiomatosis, cat-scratch disease, and peliosis hepatitis can all be caused by
Bartonella henselae
Trench fever, bacteremia, endocarditis, chronic lymphadenopathy, and bacillary angiomatosis can be caused by
Bartonella quintana
Y. pestis causes
Bubonic plague
Stool received for routine culture in most clinical laboratories in the United States should be examined for the presence of at least
Campylobacter, Salmonella, and Shigella spp.
How are these gases detected in fermentation reactions?
Can be collected in a Durham tube.
The preferred animal host of Brucella abortus is:
Cattle
In addition to the morphological, cultural, and physiological tests performed on an unknown, what tests can be conducted to further assist in it's identification?
DNA analysis.
Infection of the urinary tract is most frequently associated with:
E. coli
The most probable identity of this organism is:
E. coli
Which of the following organisms can grow in the small bowel and cause diarrhea in children, traveler's diarrhea, or a severe cholera-like syndrome through the production of enterotoxins?
E. coli
The IMViC reaction differentiates
E. coli from Enterobacter
The IMViC reaction differentiates:
E. coli from Enterobacter
The stock cultures needed for quality control testing of oxidase production are:
E. coli/Pseudomonas aeruginosa
The stock cultures needed for quality control testing of oxidase production are:
E.coli/Pseudomonas aeruginosa
E. coli 0157:H7 falls into this group:
Enterohemorrhagic
The bacteria that produces a diffuse, watery diarrhea that is said to resemble "rice water" produces which type of toxin,
Enterotoxin
129. Infection of the urinary tract is most frequently associated with:
Escherichia coli.
138. An organism gave the following reactions: TSI- acid slant/acid butt, no H2S gas produced, Indole- positive, Motility- positive, Citrate- negative, lysine decarboxylase- positive, urea- negative, VP- negative. This organism most likely is:
Escherichia coli.
139. Which of the following organisms can grow in the small bowel and cause diarrhea in children, traveler's diarrhea, or severe cholera-like syndrome through the production of exotoxins?
Escherichia coli.
156. The stock cultures needed for QC testing of oxidase production are:
Escherichia coli/ Pseudomonas aeruginosa. Pseudomonas aeruginosa is the only listed oxidase- positive.
159. QC of the spot indole test requires the use of ATCC cultures of:
Escherichia coli/Enterobacter cloacae. E. coli is positive.
202. The lab receives a blood culture from a veterinarian who has been ill for many weeks with fevers in the afternoons and evenings, arthritis and fatigue. The blood culture is positive after 5 days, and the organism has the following characteristics:
Gram stain- small, gram-negative coccobacilli; Sheep blood agar- growth after 48hrs with small, smooth, raised colonies. What should the microbiologist do next? Take extra safety precautions for possibility of Brucella.
171. A Gram stain of a touch prep from a gastric biopsy shows gram-negative bacilli that are slender and curved. The most likely pathogen is:
Helicobacter pylori.
Definitive identification of Neisseria gonorrhoeae is made with the:
Hydrolysis of carbohydrates
A mucoid, lactose positive colony type on MacConkey agar that is indole negative and citrate positive and non-motile is:
Klebsiella pneumoniae
An organism is inoculated to a TSI tube and gave the following reactions: acid slant, acid butt, no h2s, gas produced. This organism is most likely?
Klebsiella pneumoniae
The organism is most likely:
Klebsiella pneumoniae
This organism is most likely:
Klebsiella pneumoniae
155. The stock cultures needed for QC testing of motility are:
Klebsiella pneumoniae/Escherichia coli, Klebsiella is the only non motile.
134. A sputum culture from an alcoholic seen in the ER grows gray, mucoid, stringy colonies on sheep blood agar. The isolate grows readily on MacConkey agar and forms mucoid, dark pink colonies. The colonies yield the following results: ONPG- negative, Indole- negative, Glucose- positive, oxidase- negative, citrate- positive, VP- positive. The organism is most likely:
Klebsiella.
To cultivate Legionella in the laboratory, a medium supplemented with what ingredient(s) is necessary?
L-cysteine
Salmonella lab I.D.
Lactose - , catalase +, indole variable, oxidase -, motility +, citrate variable, urease -, TSI: -/+;g;H2S positive on brilliant green
145. A urine culture had the following culture results: Sheep blood swarming, Columbia CNA no growth, MAC 1. >100,000 CFU/mL nonlactose fermenter 2. >100,00 CFU/mL nonlactose-fermenter with red pigment. The isolates from MAC had the following biochemical reactions: TSI- 1 and 2 alk/acid, Urea- 1. Positive 2. Negative; TDA - 1. Positive 2. Negative; H2S- 1. Positive 2. Negative. The organisms most likely are:
Proteus mirabilis and Serratia marcescens. Serratia can produce a red pigment, P. mirabilis swarms, is TDA positive and produces H2S.
MacConkey- 1. >100,000 CFU/mL nonlactose-fermenter,Glucose- Positive- Urea- Positive- Negative,TDA- Positive- Negative,H2S- Positive- Negative, The organisms are most likely:
Proteus mirabilis and Serratia marrcescens
144. >100,000 CFU/mL of a gram-negative bacilli were isolated on MAC from a urine specimen. Biochemical results are as follows: Glucose- acid, gas produced, Indole- negative, Urea- positive, TDA- positive, H2S- positive. The organism is most likely:
Proteus mirabilis, indole reaction helps differentiate P. mirabilis (-) and P. vulgaris (+).
157. The stock cultures needed for QC testing of deaminination activity are:
Proteus mirabilis/Escherichia coli. P mirabilis is phenylalanine deaminase positive.
161. An organism isolated from the surface of a skin burn is found to produce a diffusible green pigment on a blood agar plate. Further studies of the organism would most likely show the organism to be:
Pseduomonas aeruginosa, produce the blue-green pigment, pyocyanin.
Which bacteria is known as swimmer's ear and is found to be very resistant to antibiotics in otitis externa?
Pseudomonas aeruginosa
Which of the following bacteria is a gram negative rod with a metallic sheen and grape-like odor?
Pseudomonas aeruginosa
Which of the following bacteria is associated with swimmer's ear
Pseudomonas aeruginosa
162. A nonfermenting gram-negative bacillus is isolated from a wound. The nitrate and oxidase are strongly positive. The grown on sheep blood agar has a grape like odor. The organism is:
Pseudomonas aeruginosa, often has sweet odor that smells like grapes.
A positive oxidase test will turn
Purple
With few exceptions, all members of the family Enterobacteriaceae show which of the following characteristics?
Reduce nitrate to nitrite
131. Member of the Enterobacteriaceae share which of the following characteristics?
Reduce nitrate to nitrite, also oxidase-negative and ferment glucose.
135. An organism was inoculated to a TSI tube and gave the following reactions: Alkaline slant/acid butt, H2S, gas produced. The most likely organism is:
Salmonella typhimurium.
This organism most likely is:
Salmonella typhyimurium
158. The stock cultures need for QC of deoxyribonuclease (DNase) production are:
Serratia marcescens/Escherichia coli. Serratia is positive.
The preferred animal host of Brucella melitensis is
Sheep
A TSI tube inoculated with an organism gave the following reactions: Alkaline slant, Acid butt, No H2S, No gas produced
Shigella dysenteriae
137. A TSI tube inoculated with and organism gave the following reactions: Alkaline slant, acid butt, no H2S, no gas produced. The organism is most likely:
Shigella dysenteriae.
132. Which of the following genera is among the least biochemically reactive members of the Enterobacteriaceae?
Shigella, lactose-negative, most do not produce gas, VP, urea, lysine decarboxylase and citrate- negative, and they are non motile.
Media for screening suspected cases of hemorrhagic E. coli O157:H7 must contain:
Sorbitol
130. MacConkey media for screening suspected cases of hemorrhagic E. coli 0157:H7 must contain:
Sorbitol, doesn't ferment sorbitol while other species of E. coli do.
What components of the media are included for this test?
They both contain cystein and Iron Sulfate.
Which of the following bacteria is a gram negative rod with an ammonia odor?
Stenotrophomonas maltophilia
Which of the following tests is able to differentiate Vibrio spp. from Aeromonas and Plesiomonas?
String
contains the pH indicator phenol red
TSI agars
indicates the production of H2S gas
TSI agars
Name two test that demonstrate hydrolysis of proteins or proteolytic digestion besides casein hydrolysis test.
The Tryptophan to indole test and the Litmus milk test.
167. A gastroenterologist submits a gastric biopsy from a patient with a peptic ulcer. To obtain presumptive evidence of Helicobacter pylori, a portion of the specimen should be added to which media?
Urea broth, Helicobacter pylori produce large amounts of extracellular urease and is positive for urea within 2 hrs.
name two tests for reactions that produce alkaline end products...
Urea hydrolysis and litmus milk.
Which of the following bacteria has a curved rod appearance?
Vibrio cholera
136. An isolate from stool culture gives the following growth characteristics and biochemical reactions: MAC- colorless colonies, HE- yellow-orange colonies, TSI- acid slant/acid butt no gas no H2S, Urea-positive. The screening reactions are consistent with which of the following enteric pathogens?
Yersinia enterocolitica, Shigella has colorless colonies on both MAC and HE. Yersinia is lactose negative but HE has both lactose and sucrose and produces yellow colonies from fermentation of sucrose.
133. Which of the following gram-negative bacilli ferments glucose?
Yersinia enterocolitica.
150. A 25 yr old man who had recently worked as a steward on a transoceanic grain ship presented to the ER with a high fever, diarrhea and prostration. Axillary lymph nodes were hemorrhagic and enlarged. A Wayson stain of the aspirate showed bacilli that were bipolar, resembling safety pins. The most likely identification of this organism is:
Yersinia pestis, classic for bubonic plague.
A casein test should produce...
a clear halo in the milk for a positive test result.
A starch test you must add iodine to see if the starch was broken down. You should see......
a halo for a positive result.
How is acid or alkaline detected in a culture medium as an end product?
a ph indicator such a phenol red in the broth or agar.
reacts with the pH indicator to change the color of the media from red (neutral pH) to yellow (acidic pH
acid released by the fermentation of carbohydrates
Klebsiella pneumoniae characteristics
bacteria are encapsulated to prevent phagocytosis, colonies are very mucoid and slimy in appearance, can cause pneumonia, GU infections, cystitis, wound infections, cervicitis, metritis, mastitis
why does glucose initially turn yellow but will revert back to red?
because the protein in the agar is broken down releasing alkaline products after all the glucose is used up.
Yersinia pestis characteristics
bubonic (black), pneumonic, septicemic plagues. causes swelling of the lymph nodes, skin blotches, & delirium
Enterobacter characteristics
can cause UTIs, mastitis & nosocomial infections, distributed in humans & animals as well an in H2O, sewage & soil
Phenol red lactose test media
carbohydrate fermentation
Kligler's iron agar test media
carbohydrate fermentation, hydrogen sulfide production
Skim milk agar media
casein hydrolysis
protease enzyme
casein hydrolysis
molecular oxygen product
catalase
hydrogen peroxide reagent
catalase test
Proteus mirabilis characteristics
causes wound & UTI , highly motile, dosen't form regular colonies, " swarming colonies" produces ammonia - like malodor
Salmonella characteristics
chickens, reptiles, & cattle are major reservoirs; intestional infection can eventually lead to diarrhea, vomiting, chills and a really big headache; is the only organism to turn Brilliant Green Agar green
Simmon's citrate agar media
citrate utilization
A test for Triglycerides should turn....
dark blue.
Organisms belonging to the genus Legionella are
faintly staining, thin gram-negative bacilli
Shigella lab I.D.
lactose -, catalase + ( except s. flexneri), indole -, oxidase -, motility -, citrate - , urease -, TSI: -/+;w/o g; H2s -
Proteus vulgaris lab I.D.
lactose -, catalase + , indole + , oxidase -, motility +, citrate variable, urease +, TSI: -/+; g; H2S +
K
for alkaline)
Iron sulfide
forms a black precipitate in the media, insoluable
Shigella characteristics
found only in higher primates, facultative anaerobes that cause bacillary dysentery or shigellosis, 2nd to E.coli as traveler's diarrhea
TSI agar not only indicates the production of H2S gas, but also
gives information on the ability of bacteria to ferment carbohydrates.
A/A
glucose and lactose &/or sucrose were fermented
K/A + H2S
glucose was fermented and a black ppt. is present
Organisms belonging to the genus Campylobacter are
gram-negative curved bacilli
cysteine desulurase enzyme
hydrogen sulfide production
SIM medium test media
hydrogen sulfide production, tryptophan degradation
tryptophanase enzyme
indole
Escherichia coli lab I.D.
lactose +, catalase + , indole +, oxidase -, motility +, citrate -, urease -, TSI: +/+ ;g;H2S
Klebsiella pneumoniae Lab I.D.
lactose +, catalase nonreactive to weakly reactive, indole variable, oxidase - , motility - , citrate +, urease + TSI: +/+ ;g; H2s-
Serratia lab I.D.
lactose - , catalase +, indole -, oxidase -, motility +, citrate +, urease - , TSI: (+ or -) /+; w/o g; H2S - DNase +, Lipase +, Gelatinase +
Yersinia entercolitica lab I.D.
lactose - , catalase +, indole variable, oxidase - , motile @ room temp, citrate -, urase variable, TSI: +/+, w/o gas, H2S -
