Final review questions
GNR 87 In the past, providone iodine, tincture of iodine prep pads and swabs, and other disinfectants have been recalled because of microbial contamination. The most likely organism to be isolated in these cases is A. Bordetella brochiseptica B. Klebsiella pneumonia C. Pseudomonas aeruginosa D. Serratia marcescens
Answer: C
GNR 94 Yersinia pseudotuberculosis is known to manifest commonly as which of the following clinical conditions? A. Epiglottis B. Hepatitis C. Mesenteric lymphadenitis D. Pseudomembranous colitis
Answer: C
GNR 113 Which of the following is not correct description regarding Aeromonas hydrophila? A. Beta-hemolytic B. Catalase positive C. ONPG negative D. Oxidase positive
Answer: C Aeronomas hydrophila is a lactose fermenter
2. The organism associated with a disease characterized by the presence of a pseudomembrane in the throat and the production of an exotoxin that is absorbed into the bloodstrem with a lethal effect is A. Arcanobacterium haemolyticum B. Staphylococcus aureus C. Streptococcus pyogenes D. Corynebacterium diphtheriae
D
20. A common member of the normal flora of the upper respiratory tract is A. Corynebacterium jeikeium B. Lactobacillus C. Staphylococcus epidermidis D. Viridans streptococcus
D
11. Staphylococcus saprophyticus, a recognized pathogen, is a cause of: A. Furuncles B. Impetigo C. Otitis media D. Urinary tract infections
D
26. Growth in a 48-hour semisold agar stab culture at room temperature reveals lateral filamentous growth away from the stab near the tiop of the medium. This observation is most characteristic of which organism? A. Rhodococcus sp. B. Corynecaterium urealyticum C. Enterococcus faecalis D. Listeria monocytogenes
D
3. The laboratory should be notified in advance when the physician suspects Francisella tularensis because the organism is A. fastidious and requires special medium. B. infectious for laboratory personnel. C. not culturable. D. a and b. E. b and c.
D
30. A negative PYR (L-pyrolidonyl-α-naphthylamide) test is demonstrated by a. Enterococcus faecalis b. Enterococcus faecium c. Streptococcus pyogenes d. Viridans streptococci
D
32. A child presented in August at the pediatric clinic with a superficial skin infection of the neck. The large, itchy lesions were cultured, and the diagnosis of impetigo was made. One of the etiologic agents of this clinical condition is a. Erysipelothrix rhusiopathiae b. Corynebacterium diphtheriae c. Staphylococcus saprophyticus d. Streptococcus pyogenes
D
40. Cultures of the posterior pharynx are most commonly submitted to the clinical laboratory for the detection of a. Corynebacterium diphtheriae b. Staphylococcus aureus c. Streptococcus pneumoniae d. Streptococcus pyogenes
D
46. Pleomorphic gram-positive bacilli in a Gram stain best describes a. Bacillus anthracis b. Bacillus subtilis c. Listeria monocytogenes d. Corynebacterium pseudodiphteriticum
D
55. Family members attending a picnic became ill about 2 hours after eating. The illness was characterized by rapid onset of violent vomiting. The most likely bacterial cause of such symptoms would be food poisoning caused by a. Enterococcus faecium b. Bacillus subtilis c. Listeria monocytogenes d. Staphylococcus aureus
D
6. Legionella pneumophila and Francisella tularensis share all of the following characteristics except A. poor Gram staining properties. B. ability to cause pneumonia. C. ability to diagnose infection with detection of serum antibodies. D. fluorescence of colonies.
D
54. Solubility in the presence of sodium desoxycholate is characteristic of a. Enterococcus faecalis b. Streptococcus agalactiae c. Streptococcus mutans d. Streptococcus pneumoniae
D 10% sodium deoxycholate: bile solubility reagent
45. The pulmonary form of anthrax is known as a. Valley fever b. Walking pneumonia c. Farmers's lung d. Woolsorters diseas
D Bacillus anthracis: Pulmonary anthrax (wool sorter's disease) Spores inhaled Cold/ flu-like symptoms followed by respiratory distress, coma, death 100% fatal
7. A 57-year-old male farmer sees his physician complaining of fever, night sweats, and lethargy that come and go over the past three months. The patient's history reveals that he raises sheep for wool and meat and goats for milk. The physician suspects undulant fever. What is the optimal specimen(s) for culture of this suspected organism? a. Blood b. Bone marrow c. Lymph node biopsy d. All of the above e. B and C
D Brucella: blood and bone marrow
53. Ethylhydrocupreine HCI susceptibility is a presumptive test for the identification of a. Viridans streptococci b. Streptococcus pyogenes c. Streptococcus agalactiae d. Streptococcus pneumoniae
D Ethlhydrocupreine hydrochloride: reagent of Optochin disk ("P" disk)
39. Which one of the following diseases involves erythrogenic toxin? a. Cutaneous anthrax b. Diphtheria c. Impetigo d. Scarlet fever
D Group A Streptococcus (Streptococcus pyogenes) Virulence factors Streptococcal pyrogenic exotoxins (Spe) Rash of scarlet fever (erythrogenic) Streptococcal toxic shock-like syndrome
18. The ethiologic agent of the disease erysipelas is A. Staphyloccus aureus B. Streptobacillus moniliformis C. Streptococcus agalactiae D. Streptococcus pyogenes
D Group A: Acute pharyngitis (Strep throat) Superficial skin infection Impetigo Cellulitis Erysipelas
23. The beta-hemolysis produced by group A Streptococcus seen on the surface of a sheep blood agar plate is primarily the result of streptolysin A. H B. M C. O D. S
D Streptolysin S: oxygen stabile
41. Streptococcus sanguis, a viridans streptococcus, is most commonly associated with which of the following clinical conditions? a. Otitis media b. Pharyngitis c. Relapsing fever d. Subacute bacterial endocarditis
D viridans strep: Normal flora: Oral, respiratory, GI Clinical significance: opportunistic Subacute endocarditis (SBE) Wound Brain abscess Bacteremia Meningitis S mutans: tooth decay
10. In the CAMP test, a single streak of a beta-hemolytic Streptococcus is placed perpendicular to a streak of beta-lysin-producing Staphylococcus aureus. After incubation, a zone of increased lysis in the shape of an arrowhead is noted; this indicates the presumptive identification of A. S. agalactiae B. S. bovis C. S. equinus D. S. pyogenes
A
265. Egg yolk agar showing a precipitate in the medium surrounding the colony is positive for A. Lecithinase production B. Lipase production C. Protease activity D. Starch hydrolysis
A
27. Which one of the following is not appropriate when describing Streptococcus pneumoniae? A. Bile-resistant B. Alpha-hemolytic C. Lancet-shaped, gram-positive diplococcus D. Virulent strains are encapsulated.
A
34. Which of the following organisms is able to hydrolyze sodium hippurate to benzoic acid and glycine? a. Streptococcus agalctiae b. Streptococcus pneumoniae c. Listeria monocytogenes d. Enterococcus faecalis
A
36. Which of the following is not associated with Staphylococcus aureus? a. Endotoxin production b. Clumping factor production c. Deoxyribonuclease production d. Hemolysin production
A
43. A urine culture from a 23-year-old female grew a high colony count of catalase-positive gram-positive coccus (>100,000 cfu/mL), which would most likely be a. Staphylococcus saprophyticus b. Enterococcus faecalis c. Streptococcus bovis group d. Streptococcus viridans
A
44. Cystine-tellurite blood agar plates are recommended for the isolation of a. Corynebacterium Diphtheriae b. Streptococcus agalaciae c. Streptococcus pyogenes d. Group D streptococci
A
51. The description of "Medusa head" colonies on solid agar is most characteristic of a. Bacillus anthracis b. Enterococcus faecalis c. Staphylococcus saprophyticus d. Streptococcus agalactiae
A
6. Streptococcus pyogenes can be presumptively identified using a(an) A. PYR disk B. ONPG disk C. SPS disk D. Optochin disk
A
61. The causative agent of "malignant pustule" is a. Bacillus anthracis b. Corynebacterium ulcerans c. Erysipelothrix rhusiopathiae d. Listeria monocytogenes
A
8. The virulence of Bordetella pertussis is related to its a. toxin's ability to paralyze ciliated epithelial cells. b. ability to hide in the reticuloendothelial system. C. easy dissemination. D. ability to live inside white blood cells.
A
7. A gram-positive coccus that is catalase positive, nonmotile, lysostaphin resistant, and modified oxidase positive is best identified as a member of the genus A. Micrococcus B. Lactococcus C. Pediococcus D. Staphylococcus
A Differentiation of Micrococcus and Staphylococcus: *Micrococcus is modified oxidase +, R to Lysostaphin, S to Bacitracin (0.04 units), R to Furazolidone (100 µg); obligate aerobe *Staphylcoccus is modified oxidase =, S to Lysostaphin, R to Bacitracin (0.04 units), S to Furazolidone
9. Erysipelothrix infections in humans characteristically produce A. Pathology at the point of entrance of the organism B. Central nervous system pathology C. Pathology in the lower respiratory tract D. The formation of abscesses in visceral organs
A Disease in animals: swine, turkey, sheep Human infection rare Erysipeloid: localized infection (hand/fingers) Occurs at lesion/site of inoculation Systemic infection: uncommon Rare generalized, diffuse cutaenous disease
12. The Gram stain of a blood culture on a 23-year-old pregnant woman who presented with fever and flulike symptoms in her ninth month reveal small gram-positive coccobacilli. The isolate on blood agar produced small, translucent beta-hemolytic colonies. Which of the following is the most likely etiologic agent in this case? A. Listeria monocytogenes B. Propionibacterium acnes C. Streptococcus agalactiae D. Streptococcus pyogenes
A Listeria monocytogene; Epidemiology Neonates Early onset = sepsis; high mortality Late onset = meningitis; lower mortality Pregnant females: spontaneous abortion (3rd trimester)/premature labor Clinical symptoms Assymptomatic to sub-clinical, flu-like illness
13. The etiologic agent most commonly associated with septicemia and meningitis of newborns is A. Streptococcus agalactiae B. Streptococcus bovis group C. Streptococcus pneumoniae D. Streptococcus pyogenes
A Strep group B (agalactiae) clinical significance: Disease during neonatal/perinatal period: bacteremia, pneumonia, meningitis, sepsis, neutropenia Strep pneumonia cause meningitis most commonly in adults
Unit 4 organism 1. 1. Actinobacillus actinomycetemcomitans can be distinguished from Haemophilus aphrophilus by A. its negative test for catalase. B. its positive test for lactose fermentation. C. its positive test for catalase. D. its negative test for oxidase. E. All of the above are correct.
ANS: C Differentiation of H. aphrophilus from similar organisms (e.g., A. actinomycetemcomitans) is accomplished by performing the catalase test. H. aphrophilus is catalase-negative and ferments lactose or sucrose. A. actinomycetemcomitans yields the opposite reactions in these tests.
GNR 102 Which of the following is not urease positive? A. Salmonella B. Helicobacter pylori C. Proteus mirabilis D. Yersinia enterocolitica
Answer: A
GNR 109 Violet-colored colonies are typically produced by A. Chromobacterium violaceum B. Chryseobacterium meningosepticum C. Psueudomonas aeruginosa D. Serratia marcescens
Answer: A
GNR 117 One of the most comoon etiologic agent of community-acquired uncomplicated cases of cystis is A. Enterobacter aerogenes B. E.coli C. Klebsiella pneumoniae D. Proteus vulgaris
Answer: A
GNR 46. Which of the following does NOT describe Acinetobacter sp. A. Commonly susceptible to most antimicrobials B. Generally coccobacillary in morphology C. Oxidase negative D. Infections associated with use of medical devices
Answer: A
GNR 51 A positive voges-Proskauer reaction is characteristic of A. Enterobacter aerogenes B. E. coli C. Proteus vulgaris D. Providencia rettgeri
Answer: A
GNR 56 Yersinia pestis is characteristically A. Urease negative B. Hydrogen sulfide positive C. Motile at 20-25 C D. Oxidase positive
Answer: A
GNR:19 Salmonella typhi exhibits a characteristic biochemical pattern, which differentiates it form the other salmonella. which of the following is not characteristic of S. typhi? A. Large amounts of H2S are produced in TSI agar B. Agglutination in Vi group serum C. Lysine decoarboxylase positive D. Citrate negative
Answer: A Note: S. typhy is trace H2S S. typhi is less active than other salmonella ODC-, ADH -, CIT - Specific Vi antigen
GNR 112 Some strains of Serratia marcescens produce a red-colored pigment. Pigment production is enhanced by: A. Incubation at 22 oC B. Incubation at 42 oC C. Growth on sheep blood agar D. Growth on typic soy agar without blood
Answer: A Pseudomonas aeruginosa grow on typic soy agar without blood
GNR 123 Association with faucet aerators and humidifiers used with ventilators in intensive care units is commonly a factor in outbreaks of infections with which of the following microorganisms? A. Klebsiella pneumoniae B. Pseudomonas aeruginosa C. Salmonella spp D. Serratia marcescens
Answer: B
GNR 131 A young man developed keratitis associated with the use of contact lenses that had been immersed in a contaminated cleaning solution. The most common bacterial etiologic agent in such cases is: A. Chryseobacterium meningiosepticum B. Pseudomonas aeruginosa C. Francisella tularensis D. E. Coli
Answer: B
GNR 99 A number of vacationers who traveled outside the U.S. have had their vacations interrupted by a case of "traveler's diarrhea". Which is commonly associated with which etiologic agent? A. Aeromonas hydrophila B. E.coli C. Proteus mirabilis D. Vibrio parahemolyticus
Answer: B
GNR 33 Acinetobacter baumannii A. requires cysteine B. Is oxidase negative C. Ferments glucose D. Does not grow on MacConkey agar
Answer: B Acinetobacter baumannii: is Oxidase negative (Non-fermentative gram negative bacilli) It is a saccharlytic, glucose oxidizer, growing on MacConkey agar (non-mobile)
GNR 59 Which of the following is not a characteristic of Klebsiella granulomatis? A. is often sexually transmitted B. Is isolated on Chocolate agar c. Is the causative agent of granuloma inguinale D. Can be diagnosed by detection of Donovan bodies in clinical specimens
Answer: B Klebsiella granulomatis is fastidious, can not grow on routine culture. It is diagnosed by direct examination rather than culture Wright's/Giemsa of tissue/biopsy Donovan bodies: Organism within mononuclear endothelial cells Safety pin with capsule
GNR 121 Chromic carriers, persons who remain infected with an organism for long periods, are typically associated with dissemination of A. Bordetella pertussis B. Campylobacter jejuni C. Salmonella typhi D. Yersinia pestis
Answer: C
GNR 130 Reptiles kept as pets are sometimes associated with the transmission of A. Campylobacter B. Helicobacter C. Salmonella D. Virbrio
Answer: C
GNR 52 Which of the following is NOT true regarding virulent strains of vibrio cholera? A. Adherent to enterocytes B. Mucinase production C. Nonmobile D. Toxigenic
Answer: C
GNR 79 A gram-negativve bacillus was recovered from the urine of a child with a history of recurrent urinary tract infection. The organism was oxidase negative, lactose negative, urease positive, and motile. The most likely identificaition of this agent would be A. E.coli B. Klebsiella pneumonia C. Proteus mirabilis D. Pseudomonas aeruginosa
Answer: C
GNR 28 Which of the following nonfermenters is rarely isolated in the US? A. Pseudomonas aeruginosa B. Stenotrophomonas maltophilia C. Burkholderia mallei D. Burkholderia cepacia
Answer: C Burkholderia mallei is restricted to tropical/subtropical areas of SE Asia, N. Australia, and Mexico. it is associated with Melioidosis (Granulomatous pulmonary disease) Pseudomonas aeruginosa is normal flora in 12% of stool cultures, associated with community or hospital-acquired disease (infection) Stenotrophomonas maltophilia: is the 3rd most common non-fermentative gram negative bacilli Burkholderia cepacia is causing the Severe infections in pts with cystic fibrosis (CF) and chronic granulomatous disease (CGD)
GNR 41 The method of serogrouping shigella used in the clinical laboratory is based on A. Bacteriocins B. H antigens C. K antigens D. O antigens
Answer: D
GNR 45 Infection of the gastric mucosa leading to gastritis or peptic uclers is most commonly associated with A. Campylobacter jejuni B. Helicobacter pylori C. Salmonella typhi D. Shigella sonnei
Answer: D
GNR 60 A positive DNase would be seen with A. E.coli B. Klebsiella oxytoca C. Proteus mirabilis D. Serratia marcescens
Answer: D
GNR 61 A negative citrate reaction is characteristic of A. Citrobacter freundii B. Enterobacter aerogenes C. Serratia marcescens D. Shigella boydii
Answer: D
GNR 67 Which of the following is true concerning Campylobacter jejuni? A. Catalase negative B. Isolated best at 24C C. Hydrogen sulfide positive D. A leading cause of bacterial diarrhea worldwide
Answer: D
GNR 70 Vibrio vulnificus is a well-established human pathogen that is known to cause A. Gastroenteritis B. Pneumonia C. Pyelonephritis D. Would infection
Answer: D
GNR 80 Acinetobacter baumannii is characteristically A. Mobile B. Oxidase positive C. Sensitive to penicillin D. Able to grow on MacConkey agar
Answer: D
GNR 89 Serratia spp. are unique in the family Enterobacteriaceae because of their ability to produce extracellular hydrolytic enzyme. Which of the following is not produced by Serratia species? A. DNase B. Gelatinase C. Lipase D. NADase
Answer: D
GNR 98 Swimmer's ear, a form of external otitis is commonly caused by A. Acinetobacter baumannii B. Bordetella bronchiseptica C. Haemophilus influenza D. Pseudomonas aeruginosa
Answer: D
GNR: 23 An organism occasionally misidentified as an enteric pathogen because it produces a large amount of H2S is A. Burkholderia cepacia B. Burkholderia psuedomallei C. Pseudomonas putida D. Shewanella putrefacients
Answer: D
GNR 26 Which of the following organisms would most likely produce the biochemical reactions: TSI: Red/yellow with black precipitate Urea: tan/yellow LIA: purple/purple with black precipitate A. Citrobacter freundii B. Preteus mirabilli C. Providencia rettgeri D. Salmonella
Answer: D Non-lactose fermenter ONPG - TDA - LDC + H2S - Urea- Citrobacter is excluded because it is late lactose fermenter, also LDC- Preteus and providencia are TDA +
10. You and your best friend get into a fist fight. Your knuckles are torn and bleeding afterwards. What organism are you likely to isolate if your wounds become infected? a. Kingella kingae b. Eikenella corrdens c. Aggregatibacter aphrophilus d. Cardiobacterium hominis
B
11. Because of the nature of the profession, a veterinarian is at increased risk of acquiring 1. Brucella spp. 2. Aggregatibacter actinomycetemcomitans 3. Francisella tularensis 4. Streptobacillus moniliformis 5. Eikenella corrodens A. 1, 2, 4, and 5 B. 1, 3, and 4 C. 2, 3, and 5 D. 3 and 4
B
29. Enterococcus faecium is characteristically a. Inhibited by the presence of bile in culture media b. Able to grow in the presence of high concentrations of salt c. PYR negative d. Beta-hemolytic
B
307. Resistance to clindamycin can be induced in vitro by A. Ampicillin B. Erythromycin C. Gentamicin D. Penicillin
B
35. Which of the following is not characteristic of Listeria monocytogenes? a. CAMP test positive b. Catalse negative c. Esculin hydrolysis positive d. Motile
B
47. An aerobic gram-positive rod known to cause bactermia in hospitalized immunocompromised patients is a. Bacillus anthracis b. Corynebacterium jeikeium c. Corynebacterium ulcerans d. Corynebacterium urealyticum
B
5. Legionella pneumophila and Francisella tularensis share the characteristic of: A. being easily identified by biochemical testing. B. a requirement for cysteine to grow in culture. C. the necessity for the use of Gimenez stain rather than Gram stain to visualize. D. having an animal reservoir.
B
62. An infant was hospitalized with a severe, tender erythema. The child's epidermis was loose, and large areas of skin could be peeled off. The condition described is most consistent with a clinical syndrome associated with a. Streptococcus pyogenes b. Staphylococcus aureus c. Bacillus anthracis d. Erysipelothrix rhusiopathiae
B
9. Infection due to Brucella spp. is often slow to develop, long term, and displaying periodicity. This can be explained by the organism's ability to A. colonize the upper respiratory tract prior to infection. B. travel and hide in the reticuloendothelial system. C. cause infection as the vaccine wanes in adults. D. change its surface antigens.
B
4. Abiotrophia, formerly known as nutritionally variant streptococci, will not grow on routine blood or chocolate agars because they are deficient in A. Hemin B. Pyridoxal C. Vitamin B12 D. Thiophene-2-carboxylic hydrazide
B Abiotrohpia, colony mophologically resembling viridan Strep, will not grow on routine media or BAP/CHOC without supplement Require thiol compounds or vitamin B6 to grow - Grow on supplement agar with Addition of pyridoxal disk - Grow Cross-streaking with S. aureus (satelliting will occur) - Vitamin B6-supplemented media
14. Which of the following is the most commonly isolated species of Bacillus in opportunistic infections such as bacteremia, post-traumatic infections of the eye, and endocarditis? A. B. circulans B. B. cereus C. B. licheniformis D. B. subtilis
B Bacillus cereus: 1) agent of food poisoning 2) opportunistic agent (in immunosuppressed patient) Endoopthalmitis (Post-traumatic eye infection) Endocarditis Meningitis Osteomyelitis Bacteremia/septicemia
5. Exfoliatin produced by Staphylococcus aureus is responsible for causing A. Enterocolitis B. Toxic shock syndrome C. Scalded skin syndrome D. Staphylococcal pneumonia
B Exfoliatins/ epidermolytic toxins --Proteolytic; dissolves mucopolysaccharide matrix of epidermis --Scalded skin syndrome
25. The production of H2S is one characteristic used to differentiate which of the aerobic gram-positive bacilli? A. Corynebacterium B. Erysipelothrix C. Lactobacillus D. Nocardia
B H2S in TSI
15. Loeffler's serum medium is recommended for the cultivation of A. Abiotrophia sp. B. Corynebacterium diphtheriae C. Leuconostoc sp. D. Streptococcus agalactiae
B Loeffler medium (w/ serum + egg) Stimulates characteristic microscopic morphology ( pleomorphism and metachromatic granules); not species specific; enhances characteristics of all Corynebacterium
2. Streptobacillus moniliformis is most easily isolated from blood cultures because it requires _____ for growth A. heme B. serum C. cysteine D. 1% α-ketoglutarate
B Requires blood, horse serum, or ascites fluid and CO2 Growth after 48 hrs in CO2
3. Enterotoxin produced by Staphylococcus aureus is responsible for causing A. Carbuncles B. Enterocolitis C. Impetigo D. Scalded skin syndrome
B Staphy. aureus can cause toxin-induced food poisoning (Enterocolitis) by enterotoxin A, D or B. Enterotoxin is a Heat-stable exotoxins Causative agent of: Food poisoning Toxic shock syndrome Staphylococccal pseudomembranous enterocolitis
17. Precipitates of diphtheria toxin and antitoxin formed in agar gels are an in vitro means for detecting toxigenic strains of Corynebacterium diphtheriae. The name of this test procedure is the A. D-test B. Elek test C. Hodge test D. Nagler test
B Toxin test = Elek test (anti-toxin in filter paper interacts with toxin produced by Corynebacterium diptheriaeto form precipitation line on agar plate)
59. Which of the following is associated with infections in humans often linked to deli meats and improperly pasteurized dairy products? a. Bacillus subtilis b. Listeria monocytogenes c. Leuconostoc d. Streptococcus agalactiae
B Listeria monocytogenes Primarily infects animals Humans: food-borne infection Consumption of raw dairy, processed meat
38. Which of the following species of Bacillus is nonmotile? a. B. cereus b. B. subtilis c. B. anthracis d. B. thruingiensis
C
42. Rust-colored sputum in cases of lobar pneumonia is characteristic of which of the following possible etiologic agents? a. Corynebacterium Jeikeium b. Staphylococcus aureus c. Streptococcus pneumoniae d. Streptococcus pyogenes
C
48. Which of the following is catalase negative? a. Bacillus b. Corynebacterium c. Leuconostoc d. Listeria
C
52. Which of the following is most likely to be isolated in cultures from the anterior nares of healthcare workers? a. Bacillus cereus b. Streptococcus pneumoniae c. Staphylococcus aureus d. Staphylococcus saprophyticus
C
31. A Gram stain of sputum specimen from a patient with a suspected case of lobar pneumonia reveals many white blood cells and many gram-positive cocci, which are primarily diplococci. Which of the following statements would be appropriate, given these findings? a. A PYR test should be performed on the culture islate. b. An Elek test should be performed on the culture isolate. c. An optochin test should be performed on the culture isolate. d. A hippurate hydrolysis test should be performed on the culture isolate
C B: for corynebacteria D: for group B strep
1. A test for the hydrolysis of esculin in the presence of bile is especially useful in identifying species of the genus A. Abiotrophia B. Corynebacterium C. Enterococcus D. Staphylococcus
C Enterococcus is identified by Bile esculin hydrolysis (+), growth in 6.5% salt (+), PYR +
33. An identifying characteristic of Staphylococcus aureus is a. DNase negative b. Coagulase negative c. Mannitol fermentation positive d. Growth inhibition in presence of increased salt
C Mannitol Salt Agar (MSA) Differential agent: Mannitol Staph aureus = Mannitol fermentation + Yellow colonies (phenol red indicator) = suspect SA Most coagulase-negative Staphylococccus: mannitol-negative (red colonies) Note: MSA cannot be used to definitively identify SA. MSA + colonies must be confirmed by tube coagulase results. Selective agent: 7.5% (high) salt concentration Selective for staphylococci
37. Which of the following is a characteristic of staphylococci that would help in their isolation from clinical specimens? a. Bile resistance b. Growth at 55°C c. High salt tolerance d. Resistance to novobiocin
C Mannitol Salt Agar (MSA) Selective agent: 7.5% (high) salt concentration Selective for staphylococci
16. On Tinsdale agar, colonies of Corynebacterium diphtheriae are characterized by the observance of A. Liquefaction of the agar surrounding the colonies on the medium B. Opalescent colonies with a white precipitate in the surrounding agar C. Black colonies on the culture medium surrounded by brown halos D. Pitting of the agar medium surrounding the colonies
C Picutre: Tinsdale Agar Brown/black with brown halo (suspect C. diphtheriae) C. diptheriae, C. ulcerans , and pseudotuberculosis form brown/black colonies (tellurite reduction) with halo (cystinase activity) Brown/black colonies (no halo): Other Corynebacterium species, Staph, and Strep can grow on this medium and form brown black colonies without a halo]
58. The etiologic agent of the majority of adult joint infections is a. Abiotrophia sp. b. Leuconostoc sp. c. Staphylococcus aureus d. Streptococcus pneumoniae
C Staph: Non-Toxin induced: Skin infection, Supurative wound/abscess(soft-tissue), Septicemia/bacteremia, Pneumonia, Endocarditis, Septic arthritis, Nosocomial infection, Bone, CNS infection, Peritonitis
50. The most common etiologic agent of infections associated with the surgical insertion of prosthetic devices such as artifical heart valves and cerebrospinal fluid shunts is a. Corynebacterium diphtheriae b. Staphylococcus capitis c. Staphylococcus epidermidis d. Streptococcus mutans
C o Clinical significance **Most are nosocomial Native-valve endocarditis Prosthetic valve endocarditis Intravascular catheter infections Surgical wound infection CSF shunt infection Hospital-acquired UTI
