Chapter 21: Nonfermenting and Miscellaneous Gram-Negative Bacilli. All Answers

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MULTIPLE CHOICE 1. What biochemical test will differentiate nonfermenters from Enterobacteriaceae (except Plesiomonas)? a. Oxidase b. Indole c. Citrate d. Voges-Proskauer (VP) A Most no... nfermentative gram-negative bacilli are oxidase positive, a feature that differentiates them from the Enterobacteriaceae (except Plesiomonas, which is oxidase positive). REF: 475 OBJ: Level 1: Recall 2. What substances do nonfermenters fail to ferment in traditional media? a. Lipids b. Carbohydrates c. Proteins d. Alkaloids B All of the nonfermenters fail to ferment carbohydrates and fail to produce an acid reaction in the anaerobic portion of media, such as triple sugar iron agar and Kliger’s iron agar. Some organisms may be able to acidify nontraditional media, such as 10% glucose after 7 days. REF: 475 OBJ: Level 1: Recall 3. All of the following are characteristics of nonfermenters except: a. thin gram-negative bacilli or coccobacilli. b. oxidase positive. c. indole positive. d. resistance to a variety of antimicrobials, such as aminoglycosides, third-generation cephalosporins, penicillins, and fluoroquinolones. C Some characteristics or initial clues can indicate the presence of a nonfermenter in the clinical laboratory: thin gram-negative bacilli or coccobacilli on Gram stain; oxidase-positive reaction, although reaction can be weak and variable; nonreactivity in 24 hours in commercial kit systems for the identification of Enterobacteriaceae; no acid production in the slant or butt of TSIA or KIA; and resistance to a variety of classes of antimicrobial agents, such as aminoglycosides, third-generation cephalosporins, penicillins, and fluoroquinolones. REF: 475 OBJ: Level 1: Recall 4. The three species of nonfermenters that make up the majority of isolates routinely seen in clinical laboratories include all the following except: a. Pseudomonas aeruginosa. b. Acinetobacter spp. c. Stenotrophomonas maltophilia. d. P. putida. D Three species of nonfermenters make up the majority of isolates routinely seen in clinical laboratories: P. aeruginosa, Acinetobacter spp., and S. maltophilia. REF: 476 OBJ: Level 1: Recall 5. What nonfermenter is the leading cause of nosocomial pneumonia and bacteremia? a. Pseudomonas aeruginosa b. P. fluorescens c. P. putida d. P. mendocina A P. aeruginosa is the most commonly isolated species of the genus in clinical specimens. It is an uncommon part of the normal bacterial flora and is isolated from less than 12% of normal stool specimens. It may, however, account for 5% to 15% of all nosocomial infections, especially pneumonia and bacteremia. REF: 481 OBJ: Level 2: Interpretation 6. What organism causes pulmonary disease among individuals with cystic fibrosis? a. Pseudomonas fluorescens b. P. aeruginosa c. P. putida d. P. mendocina B A large variety of clinical diseases have been documented to be caused by P. aeruginosa. This includes bacteremia, often presenting with ecthyma gangrenosum of the skin, wound infection, pulmonary disease, especially among individuals with cystic fibrosis, nosocomial urinary tract infections, endocarditis, infections following burns or trauma, and, in rare cases, central nervous system infections, including meningitis. REF: 481 OBJ: Level 2: Interpretation 7. All of the following are poor prognostic factors associated with Pseudomonas aeruginosa bacteremia except: a. septic shock. b. granulocytopenia. c. septic metastatic lesions. d. anemia. D Poor prognostic factors associated with P. aeruginosa bacteremia include septic shock, granulocytopenia, inappropriate antimicrobial therapy, and the presence of septic metastatic lesions. REF: 481 OBJ: Level 1: Recall 8. Which of the following is a virulence factor of Pseudomonas aeruginosa? a. Endotoxin b. Exotoxins c. Capsule d. All of the above D P. aeruginosa may produce a variety of factors that lend to its pathogenicity, such as endotoxin (lipopolysaccharides), motility, pili, capsule, and several exotoxins: proteases, hemolysins, lecithinase, elastase, and DNase. REF: 481 OBJ: Level 1: Recall 9. Despite all its virulence factors, what type of pathogen is Pseudomonas aeruginosa? a. Opportunistic b. Primary c. Secondary d. Commensal A Despite the vast array of virulence factors, P. aeruginosa is still an opportunistic pathogen. REF: 481 OBJ: Level 1: Recall 10. A microbiologist is reading the plates from a sputum culture. On the sheep blood agar (SBA), the microbiologist sees flat spreading colonies with a metallic sheen. On cetrimide agar, a fluorescent green color is seen in the media with clear colonies. On MacConkey, medium clear colonies are seen that have a fruity or grapelike odor. What is the most likely organism? a. Pseudomonas fluorescens b. P. aeruginosa c. P. putida d. P. stutzeri B Members of the Pseudomonas fluorescent group—which includes P. aeruginosa, P. fluorescens, P. putida, P. veronii, and P. monteilii—produce pyoverdine, a yellow-green or yellow-brown pigment. Many strains of P. aeruginosa will also produce the blue, water-soluble pigment pyocyanin. When pyocyanin combines with pyoverdine, the green color characteristic of P. aeruginosa is produced. Most isolates of P. aeruginosa are β-hemolytic on SBA and will produce flat spreading colonies with a characteristic metallic sheen. REF: 481 OBJ: Level 3: Synthesis 11. Pseudomonas aeruginosa is resistant to all the following antimicrobial agents except: a. ampicillin. b. chloramphenicol. c. trimethoprim-sulfamethoxazole. d. fluoroquinolones. D P. aeruginosa is innately resistant to many antimicrobial agents including penicillin, ampicillin, earlier generation (first and second) cephalosporins, sulfamethoxazole-trimethoprim (SXT), and chloramphenicol, along with other agents to which most gram-negative bacilli are resistant. REF: 482 OBJ: Level 1: Recall 12. What two species of Pseudomonas have been linked to transfusion-associated septicemia? a. Pseudomonas aeruginosa and P. stutzeri b. P. fluorescens and P. aeruginosa c. P. putida and P. fluorescens d. P. putida and P. mendocina C P. fluorescens and P. putida have been documented, although rarely, as causes of urinary tract infections, postsurgical abscesses, empyema, septic arthritis, and other wound infections. Both species can grow at 4 C and have been linked to transfusion-associated septicemias. REF: 483 OBJ: Level 2: Interpretation 13. What is the name of the organisms that colonize 45% of all tracheotomy patients? a. Acinetobacter spp. b. Pseudomonas aeruginosa c. P. mendocina d. P. fluorescens A If not harboring Acinetobacter spp. already, hospitalized patients may become easily colonized. As many as 45% of patients with a tracheotomy may be colonized with Acinetobacter spp. REF: 484 OBJ: Level 1: Recall 14. What organisms, which are gram-negative coccobacilli, can appear as gram-positive cocci in smears made from blood culture bottles? a. Pseudomonas putida b. Acinetobacter spp. c. Haemophilus d. Alcaligenes spp. B All of the Acinetobacter spp. are coccobacilli, oxidase-negative, catalase-positive, and nonmotile. It should be noted that Acinetobacter spp. can appear as gram-positive cocci in smears made from blood culture bottles. REF: 484 OBJ: Level 2: Interpretation 15. In what single setting does Stenotrophomonas maltophilia produce all its disease? a. Community b. Military barracks c. Nosocomial d. College dorms C With rare exceptions, S. maltophilia infections have occurred in a nosocomial setting. The single most important risk factor in the affected individuals was the presence of a venous catheter. REF: 485 OBJ: Level 1: Recall 16. What organism is associated with pneumonia in patients with cystic fibrosis or chronic granulomatous disease (CGD)? a. Stenotrophomonas maltophilia b. Pseudomonas putida c. Pseudomonas fluorescens d. Burkholderia cepacia D Clinically, B. cepacia is a low-grade, nosocomial pathogen that has most often been associated with pneumonia in patients with cystic fibrosis or chronic granulomatous disease. REF: 485 OBJ: Level 2: Interpretation 17. What nonfermenter may produce a weak, slow, positive oxidase reaction? a. Burkholderia cepacia b. Pseudomonas putida c. Stenotrophomonas maltophilia d. P. stutzeri A B. cepacia complex often produces a weak, slow, positive oxidase reaction. Nearly all strains oxidize glucose, and many will oxidize maltose, lactose, and mannitol. REF: 486 OBJ: Level 2: Interpretation 18. Which plant pathogen may be mistaken for Burkholderia cepacia? a. Pseudomonas putida b. Burkholderia gladioli c. Stenotrophomonas maltophilia d. P. stutzeri B A plant pathogen, B. gladioli resembles B. cepacia and may be mistaken for it. Isolates have been found in patients with cystic fibrosis (CF) and chronic granulomatous disease (CGD). REF: 486 OBJ: Level 1: Recall 19. What is the causative agent of glanders? a. Burkholderia cepacia b. B. gladioli c. B. mallei d. Stenotrophomonas maltophilia C B. mallei, the causative agent of glanders, is a zoonosis primarily affecting livestock such as horses, mules, and donkeys. It is rare in humans, but can cause severe local suppurative or acute pulmonary infections. REF: 486 OBJ: Level 1: Recall 20. What organism causes melioidosis? a. Burkholderia mallei b. B. cepacia c. B. gladioli d. B. pseudomallei D Burkholderia pseudomallei cause melioidosis, an aggressive granulomatous pulmonary disease caused by ingestion, inhalation, or inoculation of the organisms, with further metastatic abscess formation in lungs and other viscera. REF: 487 OBJ: Level 1: Recall 21. Burkholderia pseudomallei is found in all the following areas except: a. New Zealand. b. Northern Australia. c. Mexico. d. Southeast Asia. A The organisms are found in water and muddy soils in Southeast Asia, Northern Australia, and Mexico. REF: 487 OBJ: Level 1: Recall 22. Elizabethkingae (Chryseobacterium) meningosepticum causes all the following diseases except: a. pneumonia. b. gastroenteritis. c. endocarditis. d. meningitis. B In adults, E. meningosepticum may cause pneumonia, endocarditis, bacteremia, and meningitis. REF: 490 OBJ: Level 1: Recall 23. Characteristics of Moraxella include: a. oxidase positive and nonmotile. b. biochemically inert and aerobic. c. susceptible to penicillin and opportunistic pathogens. d. all of the above. D Members of the genus Moraxella are strongly oxidase-positive, nonmotile, and coccobacillary to bacillary gram-negative bacilli. They are, in general, biochemically inert with regard to carbohydrate oxidation. They are strictly aerobic and most often susceptible to penicillin, an unusual characteristic of the nonfermenters. These isolates are opportunists and reside on the mucous membranes of humans and lower animals, and can be isolated from the respiratory tract, urinary tract, and eyes; however, they rarely cause disease in humans. REF: 487 OBJ: Level 2: Interpretation 24. Members of the Alcaligenes are usually susceptible to all the following antibiotics except: a. aminoglycosides. b. ceftazidime. c. sulfamethoxazole-trimethoprim (SXT). d. piperacillin. A Resistance to aztreonam and the aminoglycosides is common. The asaccharolytic members of the group, A. faecalis and A. piechaudii, are usually susceptible to SXT, piperacillin, ticarcillin, ceftazidime, and quinolones (although variability occurs). Resistance to all of these antibiotics has been increasing, however, especially in the immunocompromised patient in which A. xylosoxidans is isolated. REF: 488 OBJ: Level 1: Recall 25. What organism is an opportunistic pathogen that strikes the immunocompromised patient with neutrophil deficits and produces a violet pigment on nonselective agar? a. Psychrobacter immobilis b. Chromobacterium violaceum c. Chryseomonas luteola d. Paracoccus phenylpyruvicus B C. violaceum is an opportunist, attacking the immunocompromised patient with neutrophil deficits, usually as the result of contamination of wounds with water or soil. It is motile with polar flagella and, as its name implies, produces a violet pigment about 91% of the time. REF: 489 OBJ: Level 2: Interpretation 26. What is unique about the Sphingobacterium spp.? a. Sphingomyelin in the cell wall b. Cholesterol in the cell wall c. Sphingophospholipids in the cell wall d. Collagen in the cell wall C These isolates are aflagellate but can produce gliding motility. They are oxidase-, catalase-, and esculin-positive, but indole-negative. What is unique to the group is the presence of sphingophospholipids in the cell wall. REF: 491 OBJ: Level 1: Recall 27. What is the most common member of the genus Moraxella isolated in the clinical laboratory? a. M. nonliquefaciens b. M. osloensis c. M. lacunata d. M. catarrhalis D M. catarrhalis is the most frequent isolate in the genus Moraxella from clinical specimens, especially from respiratory and ear specimens. M. nonliquefaciens is the second most commonly isolated member of the genus after M. catarrhalis. It often resides as normal flora in the respiratory tract and rarely causes disease in humans. REF: 487 OBJ: Level 1: Recall 28. Which nonfermenter is considered by government agencies to be a potential bioterrorist agent? a. Moraxella catarrhalis b. Burkholderia mallei c. Pseudomonas putida d. B. gladioli B B. mallei, the causative agent of glanders, is a zoonosis primarily affecting livestock, such as horses, mules, and donkeys. It is rare in humans but can cause severe local suppurative or acute pulmonary infections. The organism is considered by government agencies to be a potential bioterrorist agent. REF: 486 OBJ: Level 1: Recall [Show More]

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