12113990
Descripción
Test por Darla Delos Reyes, actualizado hace más de 1 año
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Creado por Darla Delos Reyes
hace casi 7 años
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Pregunta 1
Pregunta
The aseptic collection of blood cultures requires that the skin be cleansed with:
Respuesta
-
A. 2% iodine and then 70% alcohol solution
-
B. 70% alcohol and then 2% iodine or an iodophor
-
C. 70% alcohol and then 95% alcohol
-
D. 95% alcohol only
Pregunta 2
Pregunta
When cleansing the skin with alcohol and then iodine for the collection of a blood culture, the iodine (or iodophor) should remain intact on the skin for at least:
Respuesta
-
A. 10 sec
-
B. 30 sec
-
C. 60 sec
-
D. 5 min
Pregunta 3
Pregunta
What is the purpose of adding 0.025%–0.050% sodium polyanetholsulfonate (SPS) to nutrient broth media for the collection of blood cultures?
Respuesta
-
A. It inhibits phagocytosis and complement
-
B. It promotes formation of a blood clot
-
C. It enhances growth of anaerobes
-
D. It functions as a preservative
Pregunta 4
Pregunta
A flexible calcium alginate nasopharyngeal swab is the collection device of choice for recovery of which organism from the nasopharynx?
Respuesta
-
A. Staphylococcus aureus
-
B. Streptococcus pneumoniae
-
C. Corynebacterium diphtheriae
-
D. Bacteroides fragilis
Pregunta 5
Pregunta
Semisolid transport media such as Amies, Stuart, or Cary–Blair are suitable for the transport of swabs for culture of most pathogens except:
Respuesta
-
A. Neisseria gonorrhoeae
-
B. Enterobacteriaceae
-
C. Campylobacter fetus
-
D. Streptococcus pneumoniae
Pregunta 6
Pregunta
Select the method of choice for recovery of anaerobic bacteria from a deep abscess.
Respuesta
-
A. Cotton fiber swab of the abscess area
-
B. Skin snip of the surface tissue
-
C. Needle aspirate after surface decontamination
-
D. Swab of the scalpel used for débridement
Pregunta 7
Pregunta
7. Select the primary and differential media of choice for recovery of most fecal pathogens.
Respuesta
-
A. MacConkey, blood, birdseed, and Campylobacter (Campy) agars
-
B. Hektoen, MacConkey, Campy, colistin–nalidixic acid (CNA) agars
-
C. CNA and Christensen urea agars and thioglycollate media
-
D. Blood, Campy, Mueller–Hinton agars, and thioglycollate media
Pregunta 8
Pregunta
8. Select the media of choice for recovery of Vibrio cholerae from a stool specimen.
Respuesta
-
A. MacConkey agar and thioglycollate media
-
B. Thiosulfate–citrate–bile–sucrose (TCBS) agar and alkaline peptone water (APW) broth
-
C. Blood agar and selenite-F (SEL) broth
-
D. CNA agar
Pregunta 9
Pregunta
Colistin–nalidixic acid agar (CNA) is used primarily for the recovery of:
Respuesta
-
A. Neisseria species
-
B. Enterobacteriaceae
-
C. Pseudomonas aeruginosa
-
D. Staphylococcus aureus
Pregunta 10
Pregunta
10. In the United States, most blood agar plates are prepared with 5% or 10% red blood cells (RBCs) obtained from:
Respuesta
-
A. Sheep
-
B. Horses
-
C. Humans
-
D. Dogs
Pregunta 11
Pregunta
All of the following are appropriate when attempting to isolate N. gonorrhoeae from a genital specimen except:
Respuesta
-
A. Transport the genital swab in charcoal transport medium
-
B. Plate the specimen on modified Thayer–Martin (MTM) medium
-
C. Plate the specimen on New York City or Martin–Lewis agar
-
D. Culture specimens in ambient oxygen at 37°C
Pregunta 12
Pregunta
Chocolate agar and modified Thayer–Martin agar are used for the recovery of:
Respuesta
-
A. Haemophilus spp. and Neisseria spp., respectively
-
B. Haemophilus spp. and N. gonorrhoeae, respectively
-
C. Neisseria spp. and Streptococcus spp., respectively
-
D. Streptococcus spp. and Staphylococcus spp., respectively
Pregunta 13
Pregunta
Cycloserine–cefoxitin-fructose agar (CCFA) is used for the recovery of:
Respuesta
-
A. Yersinia enterocolitica
-
B. Yersinia intermedia
-
C. Clostridium perfringens
-
D. Clostridium difficile
Pregunta 14
Pregunta
Deoxycholate agar (DCA) is useful for the isolation of:
Respuesta
-
A. Enterobacteriaceae
-
B. Enterococcus spp.
-
C. Staphylococcus spp.
-
D. Neisseria spp.
Pregunta 15
Pregunta
Xylose lysine deoxycholate (XLD) agar is a highly selective medium used for the recovery of which bacteria?
Respuesta
-
A. Staphylococcus spp. from normal flora
-
B. Yersinia spp. that do not grow on Hektoen agar
-
C. Enterobacteriaceae from gastrointestinal specimens
-
D. Streptococcus spp. from stool cultures
Pregunta 16
Pregunta
A sheep blood agar plate is used as a primary isolation medium when all of the following organisms are to be recovered from a wound specimen except:
Respuesta
-
A. β-Hemolytic streptococci and coagulase-positive staphylococci
-
B. Haemophilus influenzae and Haemophilus parainfluenzae
-
C. Proteus spp. and Escherichia coli
-
D. Pseudomonas spp. and Acinetobacter spp.
Pregunta 17
Pregunta
Prereduced and vitamin K1-supplemented blood agar plates are recommended isolation media for:
Respuesta
-
A. Mycobacterium marinum and Mycobacterium avium intracellulare
-
B. Bacteroides, Peptostreptococcus, and Clostridium spp.
-
C. Proteus spp.
-
D. Enterococcus spp.
Pregunta 18
Pregunta
Which procedure is appropriate for culture of genital specimens in order to recover Chlamydia spp.?
Respuesta
-
A. Inoculate cycloheximide-treated McCoy cells
-
B. Plate onto blood and chocolate agar
-
C. Inoculate into thioglycollate (THIO) broth
-
D. Plate onto modified Thayer–Martin agar within 24 hours
Pregunta 19
Pregunta
Specimens for virus culture should be transported in media containing:
Respuesta
-
A. Antibiotics and 5% sheep blood
-
B. Saline and 5% sheep blood
-
C. 22% bovine albumin
-
D. Antibiotics and nutrient
Pregunta 20
Pregunta
Cerebrospinal fluid (CSF) should be cultured immediately, but if delayed the specimen should be:
Respuesta
-
A. Refrigerated at 4°C to 6°C
-
B. Frozen at –20°C
-
C. Stored at room temperature for no longer than 24 hours
-
D. Incubated at 37°C and cultured as soon as possible
Pregunta 21
Pregunta
The most sensitive method for the detection of β-lactamase in bacteria is by the use of:
Respuesta
-
A. Chromogenic cephalosporin
-
B. Penicillin
-
C. Oxidase
-
D. Chloramphenicol acetyltransferase
Pregunta 22
Pregunta
The breakpoint of an antimicrobial drug refers to:
Respuesta
-
A. The amount needed to cause bacteriostasis
-
B. A minimum inhibitory concentration (MIC) of 16 μg/mL or greater
-
C. A MIC of 64 μg/mL or greater
-
D. The level of drug that is achievable in serum
Pregunta 23
Pregunta
Which of the following variables may change the results of an MIC?
Respuesta
-
A. Inoculum size
-
B. Incubation time
-
C. Growth rate of the bacteria
-
D. All of these options
Pregunta 24
Pregunta
According to the Kirby–Bauer standard antimicrobial susceptibility testing method, what should be done when interpreting the zone size of a motile, swarming organism such as a Proteus species?
Respuesta
-
A. The swarming area should be ignored
-
B. The results of the disk diffusion method are invalid
-
C. The swarming area should be measured as the growth boundary
-
D. The isolate should be retested after diluting to a 0.05 McFarland standard
Pregunta 25
Pregunta
Which class of antibiotics is used for the treatment of serious gram-negative infections as well as infections with Mycobacterium tuberculosis?
Respuesta
-
A. Cephalosporins
-
B. Penicillins
-
C. Tetracyclines
-
D. Aminoglycosides
Pregunta 26
Pregunta
Select the medium best suited for the recovery of Yersinia enterocolitica from a patient with gastroenteritis.
Respuesta
-
A. Hektoen agar
-
B. Cefsulodin–Irgasan–Novobiocin (CIN) agar
-
C. Blood agar
-
D. Eosinmethylene blue agar
Pregunta 27
Pregunta
A suspected case of plague requires which of the following procedures in order to confirm Yersinia pestis?
Respuesta
-
A. Collection of multiple sets of blood cultures
-
B. Incubation of blood cultures at both 28°C and 35°C
-
C. Culture aspirates from bubos to MacConkey agar at room temperature
-
D. All of these options
Pregunta 28
Pregunta
SITUATION: Abdominal pain, fever, vomiting, and nausea prompted an elderly male to seek medical attention. A watery stool specimen producing no fecal leukocytes or erythrocytes was cultured and grew a predominance of gram-negative fermentative bacilli. The colonies were beta-hemolytic on blood agar and cream
colored on MacConkey agar. The colonies were both oxidase and catalase positive. What is the most likely identification?
Respuesta
-
A. Aeromonas hydrophilia
-
B. Escherichia coli
-
C. Salmonella spp.
-
D. Shigella spp.
Pregunta 29
Pregunta
29. SITUATION: Several attendees of a medical conference in the Gulf coast area became ill after frequenting a seafood restaurant. A presumptive identification of Vibrio cholera was made after stool specimens from several subjects grew clear colonies on MacConkey agar and yellow colonies on TCBS agar. Which key tests would help eliminate Aeromonas and Plesiomonas spp.?
Respuesta
-
A. Mannitol fermentation, Na+ requirement
-
B. Oxidase, motility
-
C. Oxidase, nitrate
-
D. Hemolysis on blood agar, catalase
Pregunta 30
Pregunta
SITUATION: A group of elementary students became ill after eating undercooked ground beef prepared in the school cafeteria. The suspected pathogen, E. coli serotype 0157:H7, is usually recovered using which of the following media?
Respuesta
-
A. XLD agar
-
B. MacConkey agar
-
C. MacConkey agar with sorbitol
-
D. Hektoen agar
Pregunta 31
Pregunta
Biochemically, the Enterobacteriaceae are gram-negative rods that:
Respuesta
-
A. Ferment glucose, reduce nitrate to nitrite, and are oxidase negative
-
B. Ferment glucose, produce indophenol oxidase, and form gas
-
C. Ferment lactose and reduce nitrite to nitrogen gas
-
D. Ferment lactose and produce indophenol oxidase
Pregunta 32
Pregunta
The ortho-nitrophenyl-β-galactopyranoside (ONPG) test is most useful when differentiating:
Respuesta
-
A. Salmonella spp. from Pseudomonas spp.
-
B. Shigella spp. from some strains of Escherichia coli
-
C. Klebsiella spp. from Enterobacter spp.
-
D. Proteus vulgaris from Salmonella spp.
Pregunta 33
Pregunta
he Voges–Proskauer (VP) test detects which end product of glucose fermentation?
Respuesta
-
A. Acetoin
-
B. Nitrite
-
C. Acetic acid
-
D. Hydrogen sulfide
Pregunta 34
Pregunta
At which pH does the methyl red (MR) test become positive?
Respuesta
-
A. 7.0
-
B. 6.5
-
C. 6.0
-
D. 4.5
Pregunta 35
Pregunta
A positive Simmons citrate test is seen as a:
Respuesta
-
A. Blue color in the medium after 24 hours of incubation at 35°C
-
B. Red color in the medium after 18 hours of incubation at 35°C
-
C. Yellow color in the medium after 24 hours of incubation at 35°C
-
D. Green color in the medium after 18 hours of incubation at 35°C
Pregunta 36
Pregunta
In the test for urease production, ammonia reacts to form which product?
Respuesta
-
A. Ammonium citrate
-
B. Ammonium carbonate
-
C. Ammonium oxalate
-
D. Ammonium nitrate
Pregunta 37
Pregunta
Which of the following reagents is added to detect the production of indole?
Respuesta
-
A. p-Dimethylaminobenzaldehyde
-
B. Bromcresol purple
-
C. Methyl red
-
D. Cytochrome oxidase
Pregunta 38
Pregunta
Decarboxylation of the amino acids lysine, ornithine, and arginine results in the formation of:
Respuesta
-
A. Ammonia
-
B. Urea
-
C. CO2
-
D. Amines
Pregunta 39
Pregunta
Lysine iron agar (LIA) showing a purple slant and a blackened butt indicates:
Respuesta
-
A. E. coli
-
B. Citrobacter spp.
-
C. Salmonella spp.
-
D. Proteus spp.
Pregunta 40
Pregunta
Putrescine is an alkaline amine product of which bacterial enzyme?
Respuesta
-
A. Arginine decarboxylase
-
B. Phenylalanine deaminase
-
C. Ornithine decarboxylase
-
D. Lysine decarboxylase
Pregunta 41
Pregunta
Which genera are positive for phenylalanine deaminase?
Respuesta
-
A. Enterobacter, Escherichia, and Salmonella
-
B. Morganella, Providencia, and Proteus
-
C. Klebsiella and Enterobacter
-
D. Proteus, Escherichia, and Shigella
Pregunta 42
Pregunta
Kligler iron agar (KIA) differs from triple-sugar iron agar (TSI) in the:
Respuesta
-
A. Ratio of lactose to glucose
-
B. Ability to detect H2S production
-
C. Use of sucrose in the medium
-
D. Color reaction denoting production of acid
Pregunta 43
Pregunta
The malonate test is most useful in differentiating which members of the Enterobacteriaceae?
Respuesta
-
A. Shigella
-
B. Proteus
-
C. Salmonella subgroups 2, 3 (the former Arizona)
-
D. Serratia
Pregunta 44
Pregunta
Which genera of the Enterobacteriaceae are known to cause diarrhea and are considered enteric pathogens?
Respuesta
-
A. Enterobacter, Klebsiella, Providencia, and Proteus
-
B. Escherichia, Salmonella, Shigella, and Yersinia
-
C. Pseudomonas, Moraxella, Acinetobacter, and Aeromonas
-
D. Enterobacter, Citrobacter, and Morganella
Pregunta 45
Pregunta
An isolate of E. coli recovered from the stool of a patient with severe bloody diarrhea should be tested for which sugar before sending it to a reference laboratory for serotyping?
Respuesta
-
A. Sorbitol (fermentation)
-
B. Mannitol (oxidation)
-
C. Raffinose (fermentation)
-
D. Sucrose (fermentation)
Pregunta 46
Pregunta
Care must be taken when identifying biochemical isolates of Shigella because serological cross reactions occur with:
Respuesta
-
A. E. coli
-
B. Salmonella spp.
-
C. Pseudomonas spp.
-
D. Proteus spp.
Pregunta 47
Pregunta
Which species of Shigella is most commonly associated with diarrheal disease in the United States?
Respuesta
-
A. S. dysenteriae
-
B. S. flexneri
-
C. S. boydii
-
D. S. sonnei
Pregunta 48
Pregunta
Which of the following tests best differentiates Shigella species from E. coli?
Respuesta
-
A. Hydrogen sulfide, VP, citrate, and urease
-
B. Lactose, indole, ONPG, and motility
-
C. Hydrogen sulfide, MR, citrate, and urease
-
D. Gas, citrate, and VP
Pregunta 49
Pregunta
Which genera of Enterobacteriaceae are usually nonmotile at 36°C?
Respuesta
-
A. Shigella, Klebsiella, and Yersinia
-
B. Escherichia, Edwardsiella, and Enterobacter
-
C. Proteus, Providencia, and Salmonella
-
D. Serratia, Morganella, and Hafnia
Pregunta 50
Pregunta
Fever, abdominal cramping, watery stools, and fluid and electrolyte loss preceded by bloody stools 2–3 days before is characteristic of shigellosis but may also result from infection with:
Respuesta
-
A. Campylobacter spp.
-
B. Salmonella spp.
-
C. Proteus spp.
-
D. Yersinia spp.
Pregunta 51
Pregunta
Cold enrichment of feces (incubation at 4°C) in phosphate-buffered saline prior to subculture onto enteric media enhances the recovery of:
Respuesta
-
A. Enterotoxigenic E. coli
-
B. Salmonella paratyphi
-
C. Hafnia alvei
-
D. Y. enterocolitica
Pregunta 52
Pregunta
Which group of tests, along with colonial morphology on primary media, aids most in the rapid identification of the Enterobacteriaceae?
Respuesta
-
A. MR and VP, urease, and blood agar plate
-
B. Phenylalanine deaminase, urease, and CDC agar plate
-
C. Bacitracin, β-lactamase, and MacConkey agar plate
-
D. Indole, oxidase, MacConkey, and blood agar plates
Pregunta 53
Pregunta
A routine, complete stool culture procedure should include media for the isolation of E. coli O157:H7 as well as:
Respuesta
-
A. Salmonella, Shigella, Yersinia, Campylobacter, and Staphylococcus aureus
-
B. Vibrio cholerae, Brucella, and Yersinia spp.
-
C. S. aureus, group B streptococci, and group D streptococci
-
D. Clostridium difficile, Clostridium perfringens, and Yersinia spp.
Pregunta 54
Pregunta
Which group of tests best identifies the Morganella and Proteus genera?
Respuesta
-
A. Motility, urease, and phenylalanine deaminase
-
B. Malonate, glucose fermentation, and deoxyribonuclease (DNase)
-
C. Indole, oxidase, MR, and VP
-
D. Indole, citrate, and urease
Pregunta 55
Pregunta
Which group of tests best differentiates Enterobacter aerogenes from Edwardsiella tarda?
Respuesta
-
A. Motility, citrate, and urease
-
B. Hydrogen sulfide (H2S) production, sucrose fermentation, indole, and VP
-
C. Lysine decarboxylase, urease, and arginine dihydrolase
-
D. Motility, H2S production, and DNase
Pregunta 56
Pregunta
Enterobacter sakazakii can best be differentiated from Enterobacter cloacae by which of the following characteristics?
Respuesta
-
A. Yellow pigmentation and negative sorbitol fermentation
-
B. Pink pigmentation and positive arginine dihydrolase
-
C. Yellow pigmentation and positive urease
-
D. H2S production on TSI
Pregunta 57
Pregunta
Members of the genus Cedecea are best differentiated from Serratia spp. by which test result?
Respuesta
-
A. Positive motility
-
B. Positive urease
-
C. Positive phenylalanine deaminase
-
D. Negative DNase
Pregunta 58
Pregunta
Which of the following organisms is often confused with the Salmonella species biochemically and on plated media?
Respuesta
-
A. E. coli
-
B. Citrobacter freundii
-
C. Enterobacter cloacae
-
D. Shigella dysenteriae
Pregunta 59
Pregunta
A gram-negative rod is recovered from a catheterized urine sample from a nursing home
patient. The lactose-negative isolate tested positive for indole, urease, ornithine decarboxylase, and phenylalanine deaminase and negative for H2S. The most probable identification is:
Respuesta
-
A. Edwardsiella spp.
-
B. Morganella spp.
-
C. Ewingella spp.
-
D. Shigella spp.
Pregunta 60
Pregunta
Which single test best separates Klebsiella oxytoca from K. pneumoniae?
Respuesta
-
A. Urease
-
B. Sucrose
-
C. Citrate
-
D. Indole
Pregunta 61
Pregunta
Which of the following organisms, found in normal fecal flora, may be mistaken biochemically for the genus Yersinia?
Respuesta
-
A. Klebsiella spp.
-
B. Proteus spp.
-
C. E. coli
-
D. Enterobacter spp.
Pregunta 62
Pregunta
Why might it be necessary for both pink (lactose-positive) and colorless (lactose-negative) colonies from an initial stool culture on MacConkey agar to be subcultured and tested further for possible pathogens?
Respuesta
-
A. Most Shigella strains are lactose positive
-
B. Most Salmonella strains are maltose negative
-
C. Most Proteus spp. are lactose negative
-
D. Pathogenic E. coli can be lactose positive or lactose negative
Pregunta 63
Pregunta
Which agar that is used for routine stool cultures is the medium of choice for the isolation of Yersinia strains from stool specimens?
Respuesta
-
A. Salmonella–Shigella agar
-
B. Hektoen enteric agar
-
C. MacConkey agar
-
D. CNA agar
Pregunta 64
Pregunta
Which organism is sometimes mistaken for Salmonella and will agglutinate in Salmonella polyvalent antiserum?
Respuesta
-
A. C. freundii strains
-
B. Proteus mirabilis strains
-
C. S. sonnei strains
-
D. E. coli
Pregunta 65
Pregunta
A bloody stool cultured from a 26-year-old woman after 3 days of severe diarrhea showed the following results at 48 hours after being plated on the following media:
MacConkey agar: little normal flora with many non–lactose-fermenting colonies
Hektoen enteric agar: many blue-green colonies
Campylobacter blood agar and C. difficile agar: no growth
Clear colonies (from MacConkey agar) tested negative for oxidase, indole, urease, motility, and H2S
The most likely identification is:
Respuesta
-
A. Shigella spp.
-
B. Salmonella spp.
-
C. Proteus spp.
-
D. E. coli
Pregunta 66
Pregunta
Which of the following organisms are generally positive for β-galactosidase?
Respuesta
-
A. Salmonella spp.
-
B. Shigella spp.
-
C. Proteus spp.
-
D. E. coli
Pregunta 67
Pregunta
In the Kauffmann–White schema, the combined antigens used for serological identification of the Salmonella spp. are:
Respuesta
-
A. O antigens
-
B. H antigens
-
C. Vi and H antigens
-
D. O, Vi, and H antigens
Pregunta 68
Pregunta
The drugs of choice for treatment of infections with Enterobacteriaceae are:
Respuesta
-
A. Aminoglycosides, trimethoprim–sulfamethoxazole, third-generation cephalosporins
-
B. Ampicillin and nalidixic acid
-
C. Streptomycin and isoniazid
-
D. Chloramphenicol, ampicillin, and colistin
Pregunta 69
Pregunta
The Shiga-like toxin (verotoxin) is produced mainly by which Enterobacteriaceae?
Respuesta
-
A. Klebsiella pneumoniae
-
B. E. coli
-
C. Salmonella typhimurium
-
D. Enterobacter cloacae
Pregunta 70
Pregunta
Infections caused by Yersinia pestis are rare in the United States. Those cases that do occur are most frequently located in which region?
Respuesta
-
A. New Mexico, Arizona, and California
-
B. Alaska, Oregon, and Utah
-
C. North and South Carolina and Virginia
-
D. Ohio, Michigan, and Indiana
Pregunta 71
Pregunta
A leg culture from a nursing home patient grew gram-negative rods on MacConkey agar as pink to dark pink oxidase-negative colonies. Given the following results, which is the most likely organism?
TSI = A/A
Indole = Neg
MR = Neg
VP = +
Citrate = +
H2S = Neg
Urease = +
Motility = Neg
Antibiotic susceptibility: resistant to carbenicillin and ampicillin
Respuesta
-
A. Serratia marcescens
-
B. Proteus vulgaris
-
C. Enterobacter cloacae
-
D. Klebsiella pneumoniae
Pregunta 72
Pregunta
Four blood cultures were taken over a 24-hour period from a 20-year-old woman with severe diarrhea. The cultures grew motile (room temperature), gram-negative rods. A urine specimen obtained by catheterization also showed gram-negative rods, 100,000 col/mL. Given the following results, which is the most likely organism?
TSI = A/A gas
Indole = +
VP = Neg
MR = +
H2S = Neg
Citrate = Neg
Urease = Neg
Lysine decarboxylase = +
Phenylalanine deaminase = Neg
Respuesta
-
A. Proteus vulgaris
-
B. Salmonella typhi
-
C. Yersinia enterocolitica
-
D. E. coli
Pregunta 73
Pregunta
A stool culture from a 30-year-old man suffering from bloody mucoid diarrhea gave the following results on differential enteric media:
MacConkey agar = clear colonies
XLD agar = clear colonies
Hektoen agar = green colonies
Salmonella–Shigella agar = small, clear colonies
Which tests are most appropriate for identification of this enteric pathogen?
Respuesta
-
A. TSI, motility, indole, urease, Shigella typing with polyvalent sera
-
B. TSI, motility, indole, lysine, Salmonella typing with polyvalent sera
-
C. TSI, indole, MR, VP, citrate
-
D. TSI, indole, MR, and urease
Pregunta 74
Pregunta
A leg-wound culture from a hospitalized 70-year-old diabetic man grew motile, lactose-negative colonies on MacConkey agar. Given the following biochemical reactions at 24 hours, what is the most probable organism?
H2S (TSI) = Neg
Indole = Neg
MR = Neg
VP = +
DNase = +
Citrate = +
Urease = Neg
Phenylalanine deaminase = Neg
Ornithine and lysine decarboxylase = +
Arginine decarboxylase = Neg
Gelatin hydrolysis = +
Respuesta
-
A. Proteus vulgaris
-
B. Serratia marcescens
-
C. Proteus mirabilis
-
D. Enterobacter cloacae
Pregunta 75
Pregunta
Three blood cultures taken from a 30-year-old cancer patient receiving chemotherapy and admitted with a urinary tract infection grew lactose-negative, motile, gram-negative rods prior to antibiotic therapy. Given the following biochemical reactions, which is the most likely organism?
H2S (TSI) = +
Indole = +
MR = +
VP = Neg
Citrate = Neg
Urease = +
DNase = +
Phenylalanine deaminase = +
Gelatin hydrolysis = +
Ornithine decarboxylase = Neg
Respuesta
-
A. Proteus vulgaris
-
B. Proteus mirabilis
-
C. Serratia marcescens
-
D. Klebsiella pneumoniae
Pregunta 76
Pregunta
Three consecutive stool cultures from a 25-year-old male patient produced scant normal fecal flora on MacConkey and Hektoen agars. However, colonies on CIN agar (cefsulodin–irgasan–novobiocin) displayed “bulls-eye” colonies after 48 hours incubation. The patient had been suffering from enterocolitis with fever, diarrhea, and abdominal pain for 2 days. What is the most likely identification of this gram-negative rod?
Respuesta
-
A. E. coli
-
B. Proteus mirabilis
-
C. Yersinia enterocolitica
-
D. Klebsiella pneumoniae
Pregunta 77
Pregunta
A 6-year-old female patient was admitted to the hospital following 2 days of severe diarrhea. Cultures from three consecutive stool samples contained blood and mucus. Patient history revealed a hamburger lunch at a fast-food
restaurant 3 days earlier. Which pathogen is most likely responsible for the following results?
Growth on:
XLD agar = yellow colonies
HE agar = yellow colonies
Mac agar = light pink and dark pink colonies
Mac with sorbitol agar – few dark pink and many colorless colonies
Respuesta
-
A. Salmonella spp.
-
B. Shigella spp.
-
C. E. coli O157:H7
-
D. Yersinia enterocolitica
Pregunta 78
Pregunta
A leg culture from a nursing home patient grew gram-negative rods on MacConkey agar as pink to dark pink oxidase-negative colonies. Given the following results, which is the most likely organism?
TSI = A/A
Indole = Neg
MR = Neg
VP = +
Citrate = +
H2S = Neg
Urease = +
Motility = Neg
Antibiotic susceptibility: resistant to carbenicillin and ampicillin
Respuesta
-
A. Serratia marcescens
-
B. Proteus vulgaris
-
C. Enterobacter cloacae
-
D. Klebsiella pneumoniae
Pregunta 79
Pregunta
Four blood cultures were taken over a 24-hour period from a 20-year-old woman with severe diarrhea. The cultures grew motile (room temperature), gram-negative rods. A urine specimen obtained by catheterization also showed
gram-negative rods, 100,000 col/mL. Given the following results, which is the most likely organism?
TSI = A/A gas
Indole = +
VP = Neg
MR = +
H2S = Neg
Citrate = Neg
Urease = Neg
Lysine decarboxylase = +
Phenylalanine deaminase = Neg
Respuesta
-
A. Proteus vulgaris
-
B. Salmonella typhi
-
C. Yersinia enterocolitica
-
D. E. coli
Pregunta 80
Pregunta
A stool culture from a 30-year-old man suffering from bloody mucoid diarrhea gave the following results on differential enteric media:
MacConkey agar = clear colonies;
XLD agar = clear colonies;
Hektoen agar = green colonies;
Salmonella–Shigella agar = small, clear colonies
Which tests are most appropriate for identification of this enteric pathogen?
Respuesta
-
A. TSI, motility, indole, urease, Shigella typing with polyvalent sera
-
B. TSI, motility, indole, lysine, Salmonella typing with polyvalent sera
-
C. TSI, indole, MR, VP, citrate
-
D. TSI, indole, MR, and urease
Pregunta 81
Pregunta
A leg-wound culture from a hospitalized 70-year-old diabetic man grew motile,
lactose-negative colonies on MacConkey agar. Given the following biochemical reactions at 24 hours, what is the most probable organism?
H2S (TSI) = Neg
Indole = Neg
MR = Neg
VP = +
DNase = +
Citrate = +
Urease = Neg
Phenylalanine deaminase = Neg
Ornithine and lysine decarboxylase = +
Arginine decarboxylase = Neg
Gelatin hydrolysis = +
Respuesta
-
A. Proteus vulgaris
-
B. Serratia marcescens
-
C. Proteus mirabilis
-
D. Enterobacter cloacae
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