Home Books Jawetz, Melnick, & Adelberg’s Medical Microbiology, 27e

Chapter 23: Mycobacteria

A 60-year-old man has a 5-month history of progressive weakness and a weight loss of 13 kg along with intermittent fever, chills, and a chronic cough productive of yellow sputum, occasionally streaked with blood. A sputum specimen is obtained, and numerous acid-fast bacteria are seen on the smear. Culture of the sputum is positive for M tuberculosis. Which treatment regimen is most appropriate for initial therapy?

(A) Isoniazid and rifampin

(B) Sulfamethoxazole–trimethoprim and streptomycin

(C) Isoniazid, rifampin, pyrazinamide, and ethambutol

(D) Isoniazid, cycloserine, and ciprofloxacin

(E) Rifampin and streptomycin

If the patient’s M tuberculosis isolate to be resistant to isoniazid, the likely mechanism for resistance is

(A) β-Lactamase

(B) Mutations in the catalase-peroxidase gene

(C) Alterations in the β subunit of RNA polymerase

(D) Mutations in the DNA gyrase gene

(E) Mutations in the genes encoding the S12 protein and 16S rRNA

A 47-year-old woman presents with a 3-month history of progressive cough, weight loss, and fever. Chest radiography shows bilateral cavitary disease suggestive of tuberculosis. Sputum culture grows an acid-fast bacillus that is a photochromogen (makes an orange pigment when exposed to light). The organism most likely is

(A) Mycobacterium tuberculosis

(B) Mycobacterium kansasii

(C) Mycobacterium gordonae

(D) Mycobacterium avium complex

(E) Mycobacterium fortuitum

A 31-year-old Asian woman is admitted to the hospital with a 7-week history of increasing malaise, myalgia, nonproductive cough, and shortness of breath. She has daily fevers of 38–39°C and a recent 5-kg weight loss. She had a negative chest radiograph when she entered the United States 7 years ago. The patient’s grandmother died of tuberculosis when the patient was an infant. A current chest radiograph is normal; results of other tests show a decreased hematocrit and liver function test abnormalities. Liver and bone marrow biopsies show granulomas with giant cells and acid-fast bacilli. She is probably infected with

(A) Mycobacterium leprae

(B) Mycobacterium fortuitum

(C) Mycobacterium ulcerans

(D) Mycobacterium gordonae

(E) Mycobacterium tuberculosis

It is very important that the patient also be evaluated for

(A) HIV/AIDS

(B) Typhoid fever

(C) Liver abscess

(D) Lymphoma

(E) Malaria

Of concern regarding the patient is that she could be infected with a Mycobacterium that is

(A) Susceptible only to isoniazid

(B) Resistant to streptomycin

(C) Resistant to clarithromycin

(D) Susceptible only to ciprofloxacin

(E) Resistant to isoniazid and rifampin

You observe a 40-year-old man begging on a street in a town in India. He has clawing of the fourth and fifth digits with loss of distal parts of the digits of both hands, strongly suggesting leprosy. The causative agent of this disease

(A) Is susceptible to isoniazid and rifampin

(B) Grows in parts of the body that are cooler than 37°C

(C) Can be cultured in the laboratory using Middlebrook 7H11 medium

(D) Is seen in high numbers in biopsies of tuberculoid leprosy lesions

(E) Commonly infects people in Texas because armadillos are hosts of M leprae

Which of the following statements about the purified protein derivative (PPD) and the tuberculin skin test is most correct?

(A) It is strongly recommended that medical and other health science students have PPD skin tests every 5 years.

(B) Persons immunized with BCG rarely, if ever, convert to positive PPD skin test results.

(C) The intradermal skin test is usually read 4 hours after being applied.

(D) A positive tuberculin test result indicates that an individual has been infected with M tuberculosis in the past and may continue to carry viable mycobacteria.

(E) A positive PPD skin test result implies that a person is immune to active tuberculosis.

A 72-year-old woman has an artificial hip joint placed because of degenerative joint disease. One week after the procedure, she has fever and joint pain. The hip is aspirated, and the fluid is submitted for routine culture and for culture for acid-fast organisms. After 2 days of incubation, there is no growth on any of the media. After 4 days, however, bacilli are seen growing on the sheep blood agar plate, and similar-appearing acid-fast bacilli are growing on the culture for acid-fast bacteria. The patient is most likely infected with

(A) Mycobacterium tuberculosis

(B) Mycobacterium chelonae

(C) Mycobacterium leprae

(D) Mycobacterium kansasii

(E) Mycobacterium avium complex

A 10-year-old child has a primary pulmonary M tuberculosis infection. Which of the following features of tuberculosis is most correct?

(A) In primary tuberculosis, an active exudative lesion develops and rapidly spreads to lymphatics and regional lymph nodes.

(B) The exudative lesion of primary tuberculosis often heals slowly.

(C) If tuberculosis develops years later, it is a result of another exposure to M tuberculosis.

(D) In primary tuberculosis, all of the infecting M tuberculosis organisms are killed by the patient’s immune response.

(E) In primary tuberculosis, the immune system is primed, but the PPD skin test result remains negative until there is a second exposure to M tuberculosis.

Which of the following statements regarding interferon-γ release assays (IGRAs) is correct?

(A) They are useful for evaluating immunocompromised patients for active tuberculosis.

(B) They detect antigens present in all Mycobacterium species.

(C) They are not available yet for testing in the United States.

(D) They are performed using molecular probes that detect organism DNA.

(E) They are used as alternatives to the tuberculin skin test to evaluate for latent tuberculosis.

M abscessus most often causes pulmonary disease among which group of individuals?

(A) Young children exposed to dirt

(B) African American smokers

(C) Elderly, nonsmoking white females

(D) Hispanic men who work outdoors

(E) Persons living in the Northwestern United States

A newly characterized rapidly growing Mycobacterium that has emerged as an important cause of central venous catheter associated infections is

(A) Mycobacterium phlei

(B) Mycobacterium mucogenicum

(C) Mycobacterium xenopi

(D) Mycobacterium smegmatis

(E) Mycobacterium terrae

The definition of extensively drug-resistant (XDR) tuberculosis includes

(A) Resistance to isoniazid

(B) Resistance to a fluoroquinolone

(C) Resistance to capreomycin, amikacin or kanamycin

(D) Resistance to rifampin

(E) All of the above

All of the following organisms are rapidly growing mycobacteria except

(A) Mycobacterium fortuitum

(B) Mycobacterium abscessus

(C) Mycobacterium mucogenicum

(D) Mycobacterium nonchromogenicum

(E) Mycobacterium chelonae

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Chapter 23: Mycobacteria

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Chapter 23: Mycobacteria

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