Microbiology - Analytic Procedures for Mycobacteriology and Nocardia spp.

17. 14-day-old colonies of a Mycobacterium species growing on Middlebrook 7H10 agar development yellow pigmentation after exposure to environmental light. From the choices listed below, select the correct presumptive identification of this photochromogenic Mycobacterium species. A. Mycobacerium chelonae B. Mycobacerium marinum C. Mycobacerium scrofulaceum D. Mycobacerium gordonae

B

18. Which of the following organisms is an acid-fast aerobic actinomycete? A. Streptomyces spp B. Nocardia spp. C. Actinomadura spp. D. Nocardiopsis spp

B

19. Which of the following Mycobacterium species is closely associated with infections in HIV positive patients? A. M. ulcerans B. M. avium-intracellulare complex C. M. simiae D. M. bovis

B

11. Mycobacterium tuberculosis can be spread from person to person via which transmission method? A. Airborne B. Injesting infected foods C. Through contact from body secretions D. Through infected saliva

A

12. The following aerobic, branching, filamentous gram-positive species is weakly acid fast and known to cause mycetomas and lung infections in immunocompromised individuals: A. Nocardia species B. Mycobacterium species C. Streptomyces species D. Corynebacterium species

A

13. Which of the following Mycobacterium species is positive for nitrate reduction? A. Mycobacterium tuberculosis B. Mycobacterium bovis C. Mycobacterium simiae D. Mycobacterium ulcerans

A

28. Which of the following species of Mycobacterium might be associated with contamination of the hot water system in large institutions such as hospitals? A. M. xenopi B. M. ulcerans C. M. marinum D. M. haemophilum

A

24. Baseline testing for latent Mycobacterium tuberculosis infection (LTBI) is recommended for all newly-hired healthcare workers. In which of these cases would a tuberculin skin test (TST) be repeated a second time, one to three weeks after the first test? A. The first test is negative and the new employee has never been tested for LTBI before. B. The first test is negative and the new employee has documentation showing he/she had a negative TST 6 months ago. C. The first test is positive. D. A positive Interferon Gamma Release Assay (IGRA) blood test.

A

20. A sputum sample from a patient with a pulmonary abscess is received in the laboratory. After several days of incubation the following findings are noted: Yellow, irregular colonies growing on a blood agar plate (BAP) under aerobic conditions. Acid-fast stain shows that the organisms are partially acid-fast. Which of the following organisms should be suspected? A. Nocardia asteroides B. Streptococcus pneumoniae C. Actinomyces israelii D. Actinomadura sp.

A

39. Which of the following is the most likely identification of an acid fast bacilli recovered from an induced sputum with these culture findings? Slow growth at 37 C Niacin test = negative Pigmented photochromogenic Nitrate test = positive Catalase = positive A. Mycobacterium kansasii B. Mycobacterium tuberculosis C. Mycobacterium simiae D. Mycobacterium chelonei

A

42. An organism isolated from a sputum specimen and appeared as a dry, wrinkled, off-white colony on sheep blood agar. A Gram stain was performed and Gram positive branching rods were seen. In addition, a modified acid fast was performed and was positive. The organism was later identified as a Norcardia species. Which of the following antibiotics is the appropriate treatment? A. Sulfonamides B. Erythromycin C. Rifampin D. Streptomycin

A

43. What is the MOST likely identification of an acid-fast bacillus that demonstrates the following characteristics? Slow growth Cream to tan colored colonies when grown in the dark Development of yellow pigment upon exposure to light A. Mycobacterium kansasii B. Mycobacterium chelonei C. Mycobacterium avium complex D. Mycobacterium scrofulaceum

A

8. The following organism is described as a branching Gram-positive bacillus that is partially acid-fast and able to hydrolyze urea, but unable to hydrolyze casein, xanthine, or tyrosine. A. Nocardia asteroides B. Nocardia brasiliensis C. Streptomyces griseus D. Actinomadura madurae

A

10. Through the use of molecular assays, Mycobacterium tuberculosis (MTB) complex can be detected directly from respiratory specimens without being concentrated. In addition, due to rifampin resistance strains of MTB complex occurring, a genetic marker can be detected to identify rifampin resistance. Which of the following genetic markers is linked to MTB complex rifampin resistance? A. erm gene B. rpoB gene C. mec A gene D. van A gene

B

15. Dry, chalky, heaped colonies growing on Middlebrook agar have a distinctive yellow-orange pigmentation. They were recovered after 5 days incubation from a subcutaneous lesion of the foot from a South American field laborer. The acid-fast stain shows slender, branching acid-fast bacilli. Casein and tyrosine were hydrolyzed. With these observations and reactions, select the species identification of this isolate. A. Nocardia asteroides B. Nocardia brasiliensis C. Mycobacterium fortuitum D. Streptomyces species

B

21. To accurately identify aerobic actinomycetes to the species level, the use of molecular methods, such 16S rRNA, can be used. However, there are limitations in identifying Nocardia and other aerobic actinomycetes by molecular methods. All of the following are limitations, EXCEPT? A. Technology and expertise B. Extracting DNA C. Information from databases D. High quality sequence data

B

23. A three-year-old female was seen by a local ear, nose and throat specialist for chronic ear pain. She had been treated several times for otitis media by her pediatrician with no resolution. Drainage from her ear grew an acid fast bacillus that gave the following biochemical reactions: Iron Uptake- Positive Nitrate reduction- Positive Arylsulfatase - Positive MacConkey agar growth, 5 days- Positive It should be identified as: A. Mycobacterium avium complex B. Mycobacterium fortuitum C. Mycobacterium chelonae D. Mycobacterium kansasii

B

25. The accumulation of niacin, as shown by a yellow reaction on the test strip is one of the chief characteristics to identify Mycobacterium tuberculosis. Another rarely encountered Mycobacterium species that also accumulates niacin is: A. Mycobacterium gordonae B. Mycobacterium simiae C. Mycobacterium xenopi D. Mycobacterium fortuitum

B

26. Which of the following culture media should be used to attempt to recover mycobacteria from a clinical specimen? A. MacConkey agar B. Lowenstein-Jensen (LJ) medium C. PPLO agar D. Modified Thayer-Martin agar

B

27. The laboratory receives a synovial fluid for acid-fast culture. How should the tech proceed with this culture? A. Digest the sample for culture B. Centrifuge the specimen and directly inoculate the culture C. Perform a direct smear only D. Reject the specimen

B

30. To identify all the species within the Mycobacterium tuberculosis (MTB) complex, the Amplified Mycobacterium Tuberculosis Direct (MTD) test can be used. The MTD test utilizes both Transcription-Mediated Amplification (TMA) and the Hybridization Protection Assay (HPA). However, before performing these tests, only certain specimen sources can be used. All of the following specimens can be used EXCEPT? A. Sputum B. Spinal fluid C. Bronchial Washing D. Tracheal aspirates

B

35. Several patients developed subcutaneous abscesses at the sites of injection of a preparation labeled "adrenal cortex injection" administered as part of a weight loss regimen. Pale-staining, filamentous acid-fast bacilli were seen in the material aspirated from the lesions (the upper photomicrograph is representative) and the colonies shown in the lower photograph grew out after 3 days incubation at 35°C in CO2. The most likely identification is: A. Mycobacterium marinum B. Mycobacterium abscessus C. Nocardia otitidiscaviarum (caviae) D. Streptomyces somaliensis

B

44. A doctor is requesting an acid-fast culture on a stool specimen. How should the tech handle this request? A. Process the sample for culture using the digestion method B. Prepare a direct smear from the sample and only digest the specimen for culture if the smear is positive C. Perform a direct smear only D. Reject the specimen as stool is an inappropriate sample for acid-fast culture

B

48. An acid-fast bacillus recovered from a post-surgery wound of a young child had the following characteristics: Rapid growth (3-5 days) on blood and chocolate agar Nitrate positive Niacin negative Urease positive Catalase 68ºC positive Iron uptake positive Which of the following Mycobacterium species does this represent? A. Mycobacterium tuberculosis B. Mycobacterium fortuitum C. Mycobacterium kansasii D. Mycobacterium avium-intracellulare

B

50. A patient grew out Mycobacterium tuberculosis (MTB) from an acid fast bacilli (AFB) sputum culture. The physician called requesting information on which four primary drugs should be used for the treatment of MTB. Which of the following primary antitubercular agents would be recommended for treatment? A. Streptomycin, Isoniazid, Rifampin, Ethambutol B. Isoniazid, Rifampin, Ethambutol, and Pyrazinamide C. Isoniazid, Ciprofloxacin, Ethambutol, and Pyrazinamide D. Isoniazid, Capreomycin, Streptomycin, Rifampin

B

9. The cellular immune response plays a role in whether a person exposed to Mycobacterium tuberculosis will develop tuberculosis disease (TB). Which of the following factors will make a person most at-risk of progressing from infection to active disease if exposed to M. tuberculosis? A. Amount of exposure B. Malnutrition C. Alcoholism D. Age of patient

B

14. Which of these methods are used to identify prior exposure to Mycobacterium tuberculosis? A. Gram stain B. White blood cell count C. Blood tests known as interferon-gamma release assays. D. Any of the above tests can be used to identify prior exposure to Mycobacterium tuberculosis.

C

16. The following steps were used in a procedure to identify M. kansasii: 1 - Extraction 2 - Denaturization 3 - Hybridization 4 - Hydrolysis of excess reagent 5 - Detection of acridinium ester Which of the following methods has been described? A. Polymerase chain reaction B. Indirect fluorescent microscopy C. Nucleic acid probes D. Lysis-centrifugation

C

46. Why is Mycobacterium tuberculosis not seen on gram stained smears? A. Mycobacterium tuberculosis stains gram positive, just too light to identify. B. Mycobacterium tuberculosis is too small to visualize in a gram stain. C. Mycobacterium tuberculosis has a waxy coating on its surface which prevents gram stain penetration. D. Mycobacterium tuberculosis have an impervious nucleocapsid.

C

29. A patient grew out Mycobacterium tuberculosis (MTB) from an acid fast bacilli (AFB) sputum culture. The physician called requesting information on alternative choices for the treatment of MTB, since the patient had tested resistant to the primary drugs of choice. Which of the following antitubercular agents would be recommended for treatment? A. Streptomycin B. Isoniazid C. Ciprofloxacin D. Ethambutol

C

3. A 34-year-old female was seen in the dermatology clinic for some lesions on her fingers that had not responded to topical antimicrobial therapy. A tissue biopsy was sent for histological examination, routine culture, acid-fast bacilli (AFB) culture, and fungal culture. There was no growth on any culture, but AFB were seen in the histological preparations. The tissue culture for AFB had been incubated at both 35oC and 32oC, in liquid media and on media with hemoglobin added for several weeks. What is the most likely diagnosis of her skin lesions? A. Buruli's ulcer B. Swimming pool granuloma C. Leprosy D. AIDS

C

49. What biosafety level (BSL) is required by the Centers for Disease Control and Prevention (CDC) for working with Mycobacterium tuberculosis, if there is a possibility that aerosols might be released? A. BSL-1 B. BSL-2 C. BSL-3 D. BSL-4

C

31. All of the following Mycobacterium species will cause tuberculosis, EXCEPT? A. Mycobacterium bovis B. Mycobacterium africanum C. Mycobacterium leprae D. Mycobacterium microti

C

32. Which of the following causative agents is most likely associated with the "swimming pool granualoma" skin lesions? A. Mycobacterium kansasii B. Mycobacterium ulcerans C. Mycobacterium marinum D. Mycobacterium xenopi

C

34. Conventional and molecular testing can both be used to identify Mycobacterium tuberculosis isolates. In fact, some molecular methods can test respiratory specimens directly without processing, which provides physicians with faster results when compared to conventional testing. When identifying Mycobacterium tuberculosis, all of the following methods can be used EXCEPT? A. Conventional testing B. Cepheid Xpert MTB/RIF Test C. MALDI-TOF D. Amplified Mycobacterium Tuberculosis Direct (MTD) Test

C

36. Due to the similarity of pulmonary and cutaneous clinical manifestations caused by Nocardia species and many other organisms, proper laboratory identification will allow for the proper selection of antimicrobial treatment, since Nocardia species are generally susceptible to: A. Penicillin B. Antifungal agents C. Sulfonamides D. All antibacterial agents

C

37. Consider the following regarding infection with Mycobacterium tuberculosis. Each response is correct EXCEPT: A. The typical route of transmission for primary tuberculosis is person to person contact via inhalation of infectious aerosols. B. Although primary tuberculosis is considered a respiratory tract disease, the infection may also affect other organs, such as the heart, lymph nodes, and central nervous system. C. A positive purified protein derivative (PPD) test always indicates the presence of active tuberculosis disease. D. Individuals with latent tuberculosis have no signs of infection and are not infectious; however, a small percentage may progress to active disease.

C

41. Which Mycobacterium species has the shortest growing time on agar media when recovered from clinical specimens? A. Mycobacterium tuberculosis B. Mycobacterium leprae C. Mycobacterium fortuitum/chelonae D. Mycobacterium malmoense

C

45. From the choices listed below, select the characteristic that would immediately rule out a presumptive identification of Mycobacterium tuberculosis: A. Positive niacin accumulation reaction B. Acid-fast bacilli arranged in parallel bundles C. Yellow pigmented colonies after exposure to light D. Positive reactions for nitrate reduction and urease

C

5. Colonies growing on Middlebrook 7H10 agar before and after exposure to light are examined. Colonies are intermediate between smooth and rough depending on the strain. Prior to light exposure, the colonies are gray white. Upon exposure to ambient light, visible yellow pigment production is observed characteristic of one of the "photochromogens". The acid-fast stain reveals slender acid fast bacilli with cross banding. Characteristic for this isolate are positive reactions for several biochemical reactions - nitrate reduction, Tween 80 hydrolysis, catalase, and urease. With these observations, select the species name of this isolate. A. Mycobacterium scrofulaceum B. Mycobacterium avium-intracellulare C. Mycobacterium kansasii D. Mycobacterium fortuitum

C

53. Norcardia species can be isolated from cutaneous specimens and can produce sulfur granules. These granules can be found in tissue specimens and can aid in detecting aerobic actinomycetes. To help identify the presence of sulfur granules in tissue specimens, which of the following methods will be most beneficial? A. Gram stain B. Acid fast stain C. KOH Mount D. Gomori methenamine-Silver (GMS)

C

54. Which Mycobacterium species will have a negative result for niacin, nitrate reduction, Tween hydrolysis (5 days), and iron uptake? A. Mycobacterium tuberculosis B. Mycobacterium kansasii C. Mycobacterium bovis D. Mycobacterium gordonae

C

55. The risk of exposure of a person to an infection of tuberculosis (TB) disease may be related to which of the following: A. Born in the United States B. High social status C. Socially disadvantaged D. Person in non-high risk groups

C

7. Within what period of time after performance of the tuberculin skin test (TST) should the result be read? A. Immediately B. 12-24 hours C. 48-72 hours D. 5-7 days

C

1. What is the first test always performed on organisms growing on solid or liquid mycobacterial media? A. Rate of growth B. Pigment production C. Catalase D. Acid-fast staining

D

2. The two most commonly used antibiotics for therapy against uncomplicated tuberculosis are: A. Rifampin and Penicillin B. Isoniazid and Penicillin C. Ampicillin and Penicillin D. Rifampin and Isoniazid

D

22. The following is the MOST likely identity of an acid-fast bacilli that showed buff colored, dry, heaped colonies; niacin, nitrate, and urease positive; and took 23 days at 35ºC to grow: A. Mycobacterium avium B. Mycobacterium kansasii C. Mycobacterium bovis D. Mycobacterium tuberculosis

D

33. Observation of each of the following characteristics is helpful in differentiating between Nocardia species and Mycobacterium species EXCEPT: A. Partial acid fast staining B. Filamentous rods that branch C. Musty basement smell of the colonies D. Gram positive staining

D

38. Which organism will infect humans and a wide range of host animals? A. Mycobacterium canettii B. Mycobacterium microti C. Mycobacterium mungi D. Mycobacterium bovis

D

4. Patterns of hydrolysis of tyrosine, xanthine, and casein are characteristics helpful in making species identifications within which genera? A. Actinomyces B. Mycobacterium C. Corynebacterium D. Nocardia

D

40. All of the following Mycobaterium species produce pigments, EXCEPT? A. Mycobacterium scrofulaceum B. Mycobacterium marinum C. Mycobacterium kansasii D. Mycobacterium fortuitum group

D

47. Which Mycobacterium sp. causes the infectious disease tuberculosis (TB)? A. Mycobacterium paratuberculosis B. Mycobacterium marinum C. Mycobacterium ulcerans D. Mycobacterium bovis

D

51. Aerobic actinomycetes can cause different types of infections. All of the following are acceptable sites for the recovery of aerobic actinomycetes EXCEPT? A. Respiratory B. Cutaneous C. Central Nervous System D. Throat

D

52. Which of the following is the most common cause of nontuberculous mycobacteria (NTM) lung disease? A. Mycobacterium ulcerans B. Mycobacterium scrofulaceum C. Mycobacterium kansasii D. Mycobacterium avium complex (MAC)

D

6. A 67-year-old homeless man was seen in the ambulatory clinic for chest pain and sputum production. A mycobacterial culture showed the following: rough, non-pigmented colonies, which grew after two weeks at 35oC and failed to grow at other temperatures, serpentine cording, a strongly positive niacin test, nitrate reduction, and loss of catalase activity after heating at 68oC in pH 7. What is the most likely identification? A. Mycobacterium bovis B. Mycobacterium intracellulare C. Mycobacterium kansasii D. Mycobacterium tuberculosis

D