Chapter 20: Vibrio, Aeromonas, Plesiomonas, and Campylobacter Species. All Answers

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MULTIPLE CHOICE 1. Which of the following is a curved, gram-negative rod that grows on TCBS agar? a. Vibrio b. Campylobacter c. Clostridium d. Fusobacterium A If a selective medium is w... arranted, because of the clinical history (exposure to seafood or seawater) or for geographic reasons (coastal area resident or recent foreign travel), thiosulfate citrate bile salts sucrose (TCBS) agar is the most widely used selective medium. REF: 461 OBJ: Level 2: Interpretation 2. What is the name of the organism that causes the disease cholera? a. Vibrio furnissii b. V. cholerae c. V. vulnificus d. V. parahaemolyticus B Vibrio spp. are commonly found in a wide variety of aquatic environments, including fresh water, brackish or estuarine water, and marine or salt water. Pandemics of cholera, a devastating diarrheal disease caused by V. cholerae, have been documented since 1817. REF: 456 OBJ: Level 1: Recall 3. Infections with Vibrio spp. can be contracted in all of the following situations except: a. increased travel to either coastal or cholera-endemic areas. b. increased consumption of seafood (particularly uncooked). c. greater numbers of Vibrio spp. in the environment. d. increased use of recreational water facilities. C Some of the various reasons for this significant rise in the isolation of Vibrio clinical isolates include increased travel to either coastal or cholera endemic areas; increased consumption of seafood (particularly uncooked); increased use of recreational water facilities, which encourages aquatic exposure; larger populations of immunocompromised individuals; and increased awareness of the existence and significance of these organisms in the clinical microbiology laboratory. REF: 456 OBJ: Level 1: Recall 4. All of the following are biochemical characteristics of Vibrio spp. except: a. ferments glucose. b. reduces nitrate to nitrite. c. halophilic. d. oxidase negative. D The vibrios are facultatively anaerobic, and all 12 clinically significant species are oxidase positive and able to reduce nitrate to nitrite. REF: 456 OBJ: Level 1: Recall 5. What disease manifests in acute cases as a severe gastroenteritis, accompanied by vomiting followed by diarrheic stools that are described as rice water and occur 10 to 30 times a day? a. Cholera b. Typhoid c. Dysentery d. Food poisoning A Cholera is an acute diarrheal disease that is spread mainly through contaminated water. The disease manifests in acute cases as a severe gastroenteritis, accompanied by vomiting followed by diarrhea. The stools produced by cholera patients are described as rice water and the number of stools, which are watery and contain numerous flecks of mucus, may be as many as 10 to 30 per day. REF: 458 OBJ: Level 2: Interpretation 6. How is cholera treated? a. Tetracycline b. Copious amounts of intravenous fluids c. Aminoglycosides with a large amount of intravenous fluids d. Rest and cold showers B Treatment and management of cholera are best accomplished by the administration of copious amounts of intravenous or oral fluids to replace fluids lost from the severe diarrhea. REF: 458 OBJ: Level 1: Recall 7. What is the name of the organism that is responsible for “summer diarrhea” in Japan? a. Vibrio cholerae b. V. vulnificus c. V. parahaemolyticus d. V. trota C V. parahaemolyticus is the second most common Vibrio species implicated in gastroenteritis. It was first recognized as a pathogen in Japan in 1950, when it was the cause of a large food-poisoning outbreak; even today, it is the No. 1 cause of “summer diarrhea” in Japan. REF: 459 OBJ: Level 1: Recall 8. A patient is brought to the emergency department with a severe case of gastroenteritis. The patient experienced gastrointestinal upset after eating raw oysters. What organism can be the culprit for this patient’s condition? a. Vibrio trota b. V. parahaemolyticus c. V. cholerae d. V. vulnificus B Vibrio parahaemolyticus is the second most common Vibrio species implicated in gastroenteritis after V. cholerae. It was first recognized as a pathogen in Japan in 1950, when it was the cause of a large food-poisoning outbreak; even today it is the No. 1 cause of “summer diarrhea” in Japan. V. parahaemolyticus has also been isolated in Europe, the Baltic area, Australia, Africa, Canada, and nearly every coastal state in the United States. The gastrointestinal disease caused by V. parahaemolyticus is generally self-limited. Patients have watery diarrhea, moderate cramps or vomiting, and little if any fever. Symptoms begin about 24 to 48 hours after ingestion of contaminated seafood. REF: 459 OBJ: Level 2: Interpretation 9. What Vibrio species is most infrequently isolated in the laboratory? a. Vibrio alginolyticus b. V. parahaemolyticus c. V. cholerae d. V. vulnificus A Of the four major Vibrio spp. likely to be encountered in the clinical laboratory, V. alginolyticus is the least pathogenic for humans and is the one most infrequently isolated. REF: 460 OBJ: Level 1: Recall 10. What species of Aeromonas is the most frequently associated with gastrointestinal infections? a. A. hydrophila b. A. caviae c. A. veronii d. A. sobria B A. caviae is the species most frequently associated with gastrointestinal infections, especially in neonate and pediatric populations, and it has been associated with inflammatory bowel disease. Other species associated with diarrhea include A. hydrophila and A. veronii (biovars sobria and veronii). REF: 464 OBJ: Level 1: Recall 11. Aeromonads have been implicated in all of the following diseases except: a. osteomyelitis. b. meningitis. c. pneumonia. d. otitis. C Aeromonads are also responsible for extraintestinal infections, with septicemia and wound infections being the most common. Aeromonads have also been implicated in cases of osteomyelitis, meningitis, pelvic abscesses, otitis, cystitis, endocarditis, peritonitis, cholecystitis, and endophthalmitis in both health and immunocompromised individuals. REF: 464 OBJ: Level 1: Recall 12. What do aeromonad colonies look like on cefsulodin-irgasan-novobiocin (CIN) agar? a. Purple colonies b. Clear colonies c. Green colonies d. Pink colonies D On CIN medium, either the standard CIN formulation for enteric Yersinia or the modified CIN II, Aeromonas will form pink-centered colonies from the fermentation of mannitol, with an uneven, clear apron-resembling Yersinia enterocolitica. However, an oxidase test performed on SBA colonies will easily separate the oxidase-positive aeromonads from the oxidase-negative Yersinia. REF: 465 OBJ: Level 1: Recall 13. What two biochemical tests help distinguish Aeromonas spp. from other enterics? a. Oxidase and indole b. Oxidase and Simmon’s citrate c. Simmon’s citrate and indole d. Voges-Proskauer (VP) and indole A An important screening procedure for aeromonads is to perform an oxidase test and a spot indole on -hemolytic colonies. A positive oxidase distinguishes aeromonads from the family Enterobacteriaceae, and most clinically isolated aeromonads are indole positive. REF: 465 OBJ: Level 1: Recall 14. Aeromonads are generally susceptible to all these antibiotics except: a. trimethoprim-sulfamethoxazole. b. ampicillin. c. aminoglycosides. d. quinolones. B As a genus, aeromonads are nearly uniformly resistant to penicillin, ampicillin, and carbenicillin except the susceptibility of Aeromonas trota. Otherwise, aeromonads are generally susceptible to trimethoprim-sulfamethoxazole, aminoglycosides, and quinolones. REF: 466 OBJ: Level 1: Recall 15. All of the following characteristics describe the genus Plesiomonas except: a. ferments glucose. b. motile. c. oxidase negative. d. facultative anaerobes. C Like the vibrios and aeromonads, Plesiomonas spp. are oxidase-positive, glucose-fermenting, facultatively anaerobic gram-negative rods that are motile by polar flagella. REF: 466 OBJ: Level 1: Recall 16. Plesiomonas spp. cause all of the following clinical types of gastroenteritis except: a. the more common watery or secretory diarrhea. b. a second subacute or chronic disease that lasts between 14 days and 2 to 3 months. c. a more invasive, dysenteric form that resembles colitis. d. a hemorrhagic diarrhea. D There are at least three major clinical types of gastroenteritis caused by Plesiomonas: the more common watery or secretory diarrhea, a second subacute or chronic disease that lasts between 14 days and 2 to 3 months, and a more invasive, dysenteric form that resembles colitis. REF: 467 OBJ: Level 1: Recall 17. What organism is the most common cause of bacterial gastroenteritis worldwide? a. Campylobacter jejuni b. C. fetus c. C. lari d. C. coli A Campylobacter spp. have been known to cause abortion in domestic animals, such as cattle, sheep, and swine. Although these organisms were suspected of causing human infections earlier, campylobacters were not established as human pathogens until sensitive isolation procedures and media were developed. Today, the most common cause of bacterial gastroenteritis worldwide is C. jejuni. REF: 468 OBJ: Level 1: Recall 18. What is the name of the organism that is strongly associated with gastric, peptic, and duodenal ulcers, as well as GI carcinoma? a. Campylobacter jejuni b. Helicobacter pylori c. C. curvus d. H. rectus B H. pylori, formerly Campylobacter pyloridis and C. pylori, has been strongly associated with gastric, peptic, and duodenal ulcers, as well as GI carcinoma. H. pylori has been identified in more than 75% of gastric ulcer patients. REF: 468 OBJ: Level 2: Interpretation 19. What organism may play a role in Guillain-Barré syndrome (GBS)? a. Helicobacter b. Aeromonas c. Campylobacter d. Plesiomonas C Strong evidence suggests that Campylobacter infection plays a role in GBS, an autoimmune disorder characterized by paralysis of the peripheral nervous system. Many patients with GBS test positive for antibodies to Campylobacter. REF: 469 OBJ: Level 2: Interpretation 20. When collecting specimens that may contain Campylobacter spp. bacteria, what transport medium should they be placed in, if a delay in transport is possible? a. Buffered glycerol-saline b. Regan-Lewis c. Aimes d. Cary-Blair D If a delay in processing the stool specimen is anticipated, it can be placed in a transport medium such as Cary-Blair to maintain the viability of the organism. A common stool transport medium, buffered glycerol-saline, is toxic to enteric campylobacters and should be avoided. REF: 469 OBJ: Level 2: Interpretation 21. Campy-BAP contains: a. Brucella agar base, 10% sheep red blood cells, vancomycin, trimethoprim, polymyxin B, amphotericin B, and cephalothin. b. Columbia agar base, 5% sheep red blood cells, erythromycin, spectinomycin, Diflucan, and ampicillin. c. Brucella agar base, 5% sheep red blood cells, Zithromax, sulfamethoxazole, nystatin, amphotericin B, and imipenem. d. Columbia agar base, glycerol, L-cysteine, hemin, streptomycin, amphotericin B, and gentamicin. A An enriched selective agar, CAMPY-BAP is a commonly used medium to isolate Campylobacter jejuni and other enteric campylobacters. This commercially available medium contains Brucella agar base, 10% sheep red blood cells, and a combination of antimicrobials: vancomycin, trimethoprim, polymyxin B, amphotericin B, and cephalothin. REF: 469 OBJ: Level 1: Recall 22. What temperature is an optimal growth temperature for Campylobacter jejuni? a. 35 C b. 42C c. 25 C d. 60 C B There is a double purpose for incubating stool cultures at 42 C to recover C. jejuni. First, C. jejuni and other enteric campylobacters grow optimally at 42 C. Second, growth of colon organisms is inhibited at this higher temperature. REF: 470 OBJ: Level 1: Recall 23. What type of an atmosphere do campylobacters require for growth? a. Microaerophilic and capnophilic b. Anaerobic and moist c. Capnophilic and halophilic d. Microaerophilic and high nitrogen content A Enteric Campylobacter and Helicobacter species require a microaerophilic and capnophilic environment. The ideal atmospheric environment for these organisms contains a gas mixture of 5% to 10% oxygen and 10% carbon dioxide. REF: 470 OBJ: Level 1: Recall 24. What organism has a microscopic morphology of tiny, curved, gram-negative rods, with S-shapes or seagull-wing shapes on Gram stain? a. Helicobacter b. Campylobacter c. Haemophilus d. Acinetobacter B Campylobacter spp. are curved, non–spore-forming, gram-negative rods that measure approximately 0.2 to 0.9 µm by 0.5 to 5.0 µm. Enteric campylobacters may appear as long spirals, S-shapes, or seagull-wing shapes. REF: 470 OBJ: Level 2: Interpretation 25. A microbiologist is working the miscellaneous bench reading stool cultures. The campy plate from a culture has growth on the plate that was incubated at 42 C. The colonies are nonhemolytic, moist, “runny looking,” and spreading. The Gram stain shows tiny gram-negative rods with some S-shapes and seagull-wing shapes. What is growing on the plate? a. Aeromonas b. Helicobacter c. Campylobacter d. Acinetobacter C The typically colonial morphology of Campylobacter jejuni and other enteric campylobacters is moist, “runny looking,” and spreading. Colonies are usually nonhemolytic; some are round and raised, whereas others may be flat. REF: 470 OBJ: Level 3: Synthesis 26. How is Helicobacter pylori presumptively identified? a. A culture of a gastric biopsy b. A culture of gastric scrapings c. A rapid oxidase test done on gastric scrapings d. A rapid urease test done on a gastric biopsy D H. pylori may be presumptively identified in a gastric biopsy specimen by testing for the presence of a rapid urease reaction. Urease activity may also be detected by the urea breath test. REF: 471 OBJ: Level 1: Recall 27. What is the drug of choice for treating intestinal campylobacteriosis? a. Erythromycin b. Gentamicin c. Vancomycin d. Imipenem A Antimicrobial susceptibility testing for Campylobacter spp. is not routinely performed in the clinical microbiology laboratory and is not standardized. The drug of choice for treating intestinal campylobacteriosis is erythromycin, although most patients recover without antimicrobial intervention. REF: 472 OBJ: Level 1: Recall [Show More]

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