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GNC,Haemophilus, Ent
Gram Negative Cocci, Haemophilus, Enterics
| Question | Answer |
|---|---|
| Voges-Proskauer = No color change Phenylalanine = No color change TSI = A/A, H2S; Citrate = Blue Lysine = Yellow (Control tube - yellow) Indole = No color change; ONPG = Yellow Urea = Yellow; Motility = Positive What is the identification? | Citrobacter species |
| Which organism can cause "traveler's diarrhea" in developing countries? | E. coli |
| Which organism is typically MUG positive and what does a positive reaction look like? | E. coli (not E. coli 0157); fluorescence |
| Which organisms produce lactose positive colonies on MAC and what is the expected appearance of the organisms? | E. coli, Klebsiella & Enterobacter are lactose + & produce red/pink colonies |
| Which organism causes most urinary tract infections? | E. coli |
| Voges-Proskauer = Pink; Phenylalanine = No color change KIA = A/A; Citrate = Blue Lysine = Purple (Control tube - yellow) Indole = No color change; ONPG = Yellow Urea = Pink; Motility = Positive DNAse = No clearing What is the identification? | Enterobacter species |
| Voges-Proskauer = No color change Phenylalanine = No color change Kligler iron agar = Yellow/yellow; Citrate = Green Lysine = Purple (Control tube - yellow); Indole = Red ONPG = Yellow; Urea = Yellow; Motility = Positive What is the identification? | Escherichia coli |
| Which of the Haemphilus species are NOT normal flora? | H. ducreyi & H. aegyptius |
| Which two Haemophilus species require X and V factors for growth? | H. haemolyticus (hemolytic) & H. influenzae (nonhemolytic) |
| Which two Haemophilus species require V factor for growth? | H. parahinfluenzae (nonhemolytic) & H. parahaemolyticus (hemolytic) |
| Which two Haemophilus species are porphyrin test positive (fluorescence)? | H. parainfluenzae (no hemolysis present) & H. parahaemolyticus (hemolysis) |
| Which organism causes pinkeye? | Haemophilus aegyptius |
| Which organism is transmitted sexually and causes a chancroid or soft chancre? | Haemophilus ducreyi |
| Which gram negative bacilli satellite around staphylococci on sheep blood agar? What nutrient is supplied by the staphylococci? | Haemophilus; V factor (NAD) |
| Which two enteric organisms are nonmotile? | Klebsiella & Shigella |
| Voges-Proskauer = Pink; Phenylalanine = No color change TSI = A/A; Citrate = Blue Lysine = Purple (Control tube - yellow) Indole = No color change; ONPG = Yellow Urea = Pink; Motility = Negative What is the identification? | Klebsiella pneumoniae |
| The technologist isolated gram negative diplococci from a sputum specimen. The following results are obtained: CHO utilization: glucose =, maltose =, lactose =, sucrose =, nitrate +, DNAse + What is the identification of the isolate? | Moraxella catarrhalis |
| Chromogenic substrate tests were performed on a respiratory isolate. The following results were obtained: Hydroxyprolylaminopeptidase = Gamma-glutamylaminopeptidase = Beta-glactosidase = Butyrate esterase + What is the identification of the organism? | Moraxella catarrhalis |
| Voges-Proskauer = No color change; Phenylalanine = Green TSI = K/A; Citrate = Green Lysine = Yellow (Control tube - yellow); Indole = Red ONPG = No color change; Urea = Pink; Motility = Positive What is the identification? | Morganella morganii |
| The technologist isolated gram negative diplococci from a vaginal specimen. The following results were obtained: CHO utilization: glucose +, maltose =, lactose =, sucrose =, nitrate =, & DNAse = What is the identification of the isolate? | Neisseria gonorrhoeae |
| Chromogenic substrate tests were performed on a genital isolate. The following results were obtained: Hydroxyprolylaminopeptidase + Gamma-glutamylaminopeptidase = Beta-glactosidase = Butyrate esterase = What is the identification of the organism? | Neisseria gonorrhoeae |
| The technologist isolated gram negative diplococci from a throat specimen. The following results are obtained: CHO utilization: glucose +, maltose +, lactose +, sucrose =, nitrate =, DNAse = What is the identification of the isolate? | Neisseria lactamica |
| Chromogenic substrate tests were performed on a respiratory isolate. The following results were obtained: Hydroxyprolylaminopeptidase + Gamma-glutamylaminopeptidase = Beta-glactosidase + Butyrate esterase = What is the identification of the organism? | Neisseria lactamica |
| The technologist isolated gram negative diplococci from a spinal fluid. The following results were obtained: CHO utilization: glucose +, maltose +, lactose =, sucrose =, nitrate =, DNAse = What is the identification of the isolate? | Neisseria meningitidis |
| Chromogenic substrate tests were performed on a CSF isolate. The following results were obtained: Hydroxyprolylaminopeptidase = Gamma-glutamylaminopeptidase + Beta-glactosidase = Butyrate esterase = What is the identification of the organism? | Neisseria meningitidis |
| Name an organism that gives a positive oxidase reaction and describe a positive reaction. | Neisseria species & M. catarrhallis are positive; dark BLUE is positive |
| Voges-Proskauer = No color change; Phenylalanine = Green Triple sugar iron agar = Red/black; Citrate = Green Lysine = Yellow (Control tube - yellow) Indole = No color change; ONPG = No color change Urea = Pink; Motility = Positive | Proteus mirabilis |
| Voges-Proskauer = No color change; Phenylalanine = Green TSI = A/A, H2S; Citrate = Blue Lysine = Yellow (Control tube - yellow); Indole = Red ONPG = No color change; Urea = Pink; Motility = Positive What is the identification? | Proteus vulgaris |
| Name three enteric organisms that are indole positive and describe a positive reaction. | Proteus vulgaris, E. coli, Klebsiella oxytoca; positive reaction is RED |
| Name some enteric organisms that are phenylalanine deaminase positive and describe a positive reaction. | Proteus species, Providencia species, & Morganella morganii; GREEN is positive |
| Voges-Proskauer = No color change; Phenylalanine = Green TSI = Red/yellow; Citrate = Blue Lysine = Yellow (Control tube - yellow); Indole = Red ONPG = No color change; Urea = Pink; Motility = Positive What is the identification? | Providencia species |
| What three organisms give different reactions on the TSI & KIA? | S. marcescens, Y. enterocolitica & P. vulgaris |
| Which two enteric pathogens produce lactose negative colonies on EMB and what is the expected appearance of the organisms? | Salmonella & Shigella are lactose negative & produce colorless colonies |
| Name three enteric organisms that are citrate positive and describe a positive reaction. (There are more that three enterics that are citrate + but the citrate reaction is a key identifying reaction for three of the organisms.) | Salmonella, Citrobacter & Providencia; BLUE is positive |
| Which organisms produce the following KIA reaction? K/A, H2S | Salmonella, Proteus, & Citrobacter |
| Voges-Proskauer = No color change Phenylalanine = No color change TSI = Red/black; Citrate = Blue Lysine = Purple (Control tube - yellow) Indole = No color change; ONPG = No color change Urea = Yellow; Motility = Positive What is the identification? | Salmonella species |
| Which organism and disease are associated with "rose spots"? What are "rose spots"? | Salmonella Typhi; typhoid fever; red lesions on the abdomen |
| Voges-Proskauer = Pink; Phenylalanine = No color change KIA = Red/yellow; Citrate = Blue Lysine = Purple (Control tube - yellow); Indole = No color change ONPG = Yellow; Urea = Yellow DNAse = Clearing; Motility = Positive What is the identification? | Serratia marcescens |
| Which enteric organism is DNAse positive & what does a positive reaction look like? | Serratia marcescens; media turns pink (or clearing of medium) |
| Which organism is unable to decarboxylate or deaminate lysine & what is the expected LIA result? | Shigella = K/A (purple/yellow) |
| Voges-Proskauer = No color change Phenylalanine = No color change Kligler iron agar = K/A; Citrate = Green Lysine = Yellow (Control tube - yellow) Indole = No color change; ONPG = No color change Urea = Yellow; Motility = Negative | Shigella species |
| Which organism is spread by 4 Fs and what are the 4 Fs? | Shigella; food, feces, fingers, & flies |
| Which organism causes plague? | Yersinia pestis |
| Which organisms decarboxylate lysine & what are the expected LIA results? | E. coli = K/K (purple/purple) & Salmonella = K/K, H2S (purple/purple, H2S) |
| Which organisms can causes hemolytic uremic syndrome (HUS) and hemorrhagic colitis? | Enterohemorrhagic E. coli strains, including E. coli 0157:H7 |
| Which organism deaminates lysine & what is the expected LIA result? | Proteus; R/A |
| Which organism can cause a disease that mimics appendicitis? | Yersinia enterocolitica |
| How are enterohemorrhagic E. coli strains detected? | By detecting Shiga-toxins using PCR, EIA, or cytotoxicity assay |
| What is the correct atmosphere for incubating Neisseria gonorrhoeae and Neisseria meningitidis | CO2 |
| All lactose negative organisms on enteric plate media such as EMB will give a negative reaction on the ONPG test. True or False | False; some lactose negative organisms are slow lactose fermenters |
| Which tube media detects H2S? | KIA, TSI, LIA, & SIM |
| When reading the lysine decarboxylase test at 12 hours both the test and control tubes are yellow. How should these results be interpreted? | Acid is produced when the MO uses glucose; reincubate for at least 6 more hours |
| What reagents are used for the Voges-Proskauer test? | Alpha-naphthol & 40% KOH |
| What endproduct is produced when urease breaks down urea? | Ammonia |
| Which culture media supports the growth of Neisseria meningitidis? | BAP, CHOC, & selective media (MTM, ML, NYC, GLC) |
| Which enzyme breaks down lactose into glucose & galactose? | Beta-galactosidase |
| The substrate in the MUG test is broken down by _____________ to form 4-methylumbelliferone. | Beta-glucuronidase |
| What media should be set-up for GC request on joint fluid culture? | Blood agar & chocolate agar |
| What media should be set-up for GC request on genital culture? | Blood agar & selective GC agar |
| Which culture media supports the growth of Neisseria gonorrhoeae? | CHOC, & selective media (MTM, ML, NYC, or GLC) |
| What medium is used to isolate Yersinia enterocolitica, at what temperature is the plate incubated, and what do the colonies look like? | CIN; incubate at room temperature, bull's eyes (red center & clear edges) |
| What is the correct atmosphere for incubating TSA or MH agar inoculated with suspected Haemophilus with X & V strips? | CO2 |
| An organism produces blue-green colonies w/ black centers on HE agar. What is the expected appearance of this organism on MAC agar? | Colorless colonies |
| Gram negative diplococci was isolated from a genital culture of a 11 year old girl. Using carbohydrate utilization tests the organism was identified as N. gonorrhoeae. The technologist should: | Confirm the identification using another test method other than molecular tests. |
| When reading the lysine decarboxylase test at 18 hours the test tube is purple and control tube is yellow. How should these results be interpreted? | Control result correct; MO decarboxylates lysine |
| What is the purpose of using the LIA? | Detect Salmonella from stool specimens |
| What sugars are being fermented in the following KIA reaction and which organisms produce this result? A/A (acid/acid; yellow/yellow) | Glucose & lactose are fermented; E. coli, Klebsiella & Enterobacter |
| What sugars are being fermented in the following KIA reaction and which organisms produce the following result? KIA = K/A (alkaline/acid; red/yellow) | Glucose is fermented; Shigella, Providencia & Morganella |
| What is the appearance of H. ducreyi on Gram stain? | Gram negative bacilli in "school of fish" morphology |
| How is hemolysis detected for Haemophilus species? | Growth on horse or rabbit blood or satellite test on sheep blood agar |
| Growth on horse or rabbit blood or satellite test on sheep blood agar | H2S production; indole; & motility |
| What test is used to separate Klebsiella pneumoniae from K. oxytoca? | Indole; K. pneumoniae is indole negative & K. oxytoca is indole positive |
| Should chocolate agar be used to detect X & V growth requirements for Haemophilus isolates? Why or why not. | No, because it contains both X & V factors. |
| How do the KIA & TSI tests differ? | KIA detects glucose & lactose fermentation; in addition TSI detects sucrose |
| What is the next step in identifying Salmonella or Shigella isolates if serogrouping fails to produce agglutination? | Make suspension of isolate, heat to remove capsular AGN, & retest isolate |
| The 12 hour result for the LIA test are K/A (purple/yellow). How should these results be interpreted? | MO uses glucose & produces acid in butt of tube; reincubated for 6 more hours |
| A direct gram stain of a urethral discharge showing intracellular gram negative diplococci is diagnostic for Neisseria gonorrhoeae. Would the same be true for endocervical specimens? | No - females possess normal genital flora that can mimic GC on gram stain |
| What sugars are being fermented in the following KIA reaction and which organisms produce this result? K/K or K/NC | No sugars are used; MOs use peptones; Pseudomonas & Acinetobacter |
| Is XLD typically used to isolate pathogens from specimens such as urine or wounds? | NO; EMB or MAC would be used; XLD, SS & HE are used for stools only |
| What is the most sensitive method for detecting Neisseria gonorrhoeae from patient specimens? | Nucleic acid amplification tests (NAAT) |
| How long is the expiration date for a newly opened oxidase ampule? | One day - new reagent has to be opened daily |
| Can the following specimens be gram stained to detect GC? Throat swab Rectal swab Genital specimens | Only the genital specimens can be gram stained to examine for GC |
| What three characteristics are common to enterics? | Oxidase = (except Plesiomonas), glucose fermented, & nitrate + (almost all) |
| What type of media should be used when performing the oxidase test? | Perform test off of BA or CHOC; differential media can give false results |
| An organism produces pink colonies with precipitated bile on MAC agar. What is the expected appearance of this organism on SS? | Pink colonies |
| An organism produces colorless colonies w/ black centers on SS agar. What is the expected appearance of this organism on XLD? | Red colonies w/ black centers |
| Name two enrichment broths used to isolate Salmonella and Shigella. | Selenite (primarily for Salmonella) & Gram-negative broth (GN) |
| What medium is used to isolate E. coli 0157 and what do the colonies look like? | Sorbitol-MacConkey (SMAC); colonies are colorless because MO can't use sorbitol |
| The following gram negative diplococci is from a genital specimen. It was set-up on MTM & CHOC. The tests were performed from growth on the CHOC: Hydroxyprolylaminopeptidase + Gamma-glutamylaminopeptidase = Beta-glactosidase = Butyrate esterase = | Tests are invalid. Tests MUST be performed from gonoccoccal selective media. |
| Why does Y. enterocolitica give different results on KIA (K/A) & TSI (A/A)? | The MO doesn't ferment lactose in KIA but does ferment sucose in TSI |
| What are the urease and motility tests results for Yersinia enterocolitica? | Urease positive; motility positive at 25 C & negative at 35 C |
| What identification tests can be performed on a pleomorphic GNB that only grows on chocolate agar (no growth on blood agar and MAC)? | X & V strips/disks or porphyrin test & hemolysis check |
| What components are included in the Quad plate for identification of Haemophilus? | X, V, XV, & horse blood for detection of hemolysis |
| Are the following specimens acceptable for isolation of GC? Throat swab Rectal swab Genital specimens | Yes, all can be cultured for GC |
| What enzyme is detected when using the ONPG test and what does a positive reaction look like? | ß-galactosidase is detected & a positive reaction is YELLOW |
Created by:
Mwortman
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