Chapter 18: Haemophilus and Other Fastidious Gram-Negative Bacilli. All ANswers

MULTIPLE CHOICE 1. All of the following are characteristics of Haemophilus spp. except: a. gram-positive cocci. b. small coccobacilli. c. oxidase positive. d. catalase positive. A The genus Haemophilus con ...

MULTIPLE CHOICE 1. All of the following are characteristics of Haemophilus spp. except: a. gram-positive cocci. b. small coccobacilli. c. oxidase positive. d. catalase positive. A The genus Haemophilus consists of gram-negative, pleomorphic coccobacilli or rods that may vary microscopically from small coccobacilli in direct smears of clinical material to long filaments occasionally seen in stained smears of colony growth. They are nonmotile, facultatively anaerobic, ferment carbohydrates, are generally oxidase and catalase positive, reduce nitrates to nitrites, and are obligate parasites on the mucous membranes of humans and animals. REF: 391 OBJ: Level 1: Recall 2. Which species are associated with infections in humans? a. Haemophilus influenzae b. H. aegyptius c. H. ducreyi d. All of the above D According to Bergey’s Manual of Systemic Bacteriology, 10 species of Haemophilus are associated with hum H. influenzae, H. parainfluenzae, H. haemolyticus, H. parahaemolyticus, H. aphrophilus, H. paraphrophilus, H. paraphrohaemolyticus, H. aegyptius, H. segnis, and H. ducreyi. REF: 391 OBJ: Level 1: Recall 3. A microbiologist is reading a sputum culture and notices tiny, translucent colonies growing closely around a -hemolytic colony on sheep blood agar (SBA). In fact, the colonies are growing in the area where the blood has been hemolyzed. What is the probable identity of the organism that is growing closely to the -hemolytic organism, and why are they growing in the hemolyzed area? a. Neisseria spp., because they need the factor X in this area b. Haemophilus spp., because they need the factor V in this area c. Acinetobacter spp., because they need the factors X and V d. Alcaligenes spp., because they require antibiotics be added to the media B A phenomenon that helps in the recognition of Haemophilus spp., which require V factor, is satellitism. Satellitism occurs when an organism such as Staphylococcus aureus, Streptococcus pneumoniae, or Neisseria spp. produces V factor as a by-product of its metabolism. On SBA plates, tiny colonies of Haemophilus may be seen growing or engaging in satellitism around the V factor-producing organism. REF: 392 OBJ: Level 3: Synthesis 4. Which one of the virulence factors associated with Haemophilus spp. plays the most significant role in the invasiveness of the organism? a. IgA protease b. Pili c. Capsule d. Enterotoxin C Of all the potential virulence factors, the capsule, if present, plays the most significant role. Before widespread use of a vaccine, most invasive infections were caused by encapsulated strains of H. influenzae belonging to capsular serotype b and occurred primarily in young children. REF: 392 OBJ: Level 1: Recall 5. A mother brings her lethargic, feverish baby into the emergency department. The baby is diagnosed with meningitis and the doctor does a spinal tap. The cerebrospinal fluid (CSF) Gram stain shows many tiny gram-negative rods. What is the most probable identification of this organism? a. Haemophilus influenzae serotype b b. H. parainfluenzae c. H. aegyptius d. H. aphrophilus A Until recently, serotype b (H. influenzae) had been a common cause of pediatric meningitis in children between the ages of 3 months and 6 years. Bloodstream invasion and bacteremic spread follow colonization, invasion, and replication of this organism in the respiratory mucous membranes. Headache, stiff neck, and other meningeal signs are usually preceded by mild respiratory distress. REF: 393 OBJ: Level 3: Synthesis 6. What is the name of the disease that is characterized by rapid onset, acute inflammation, and intense edema that may cause complete airway obstruction in 2- to 4-year-olds? a. Cellulitis b. Epiglottitis c. Meningitis d. Conjunctivitis B The manifestations of epiglottitis include rapid onset, acute inflammation, and intense edema that may cause complete airway obstruction, requiring an emergency tracheostomy. Because of the possibility of causing further damage, the area is not swabbed for culture, but is treated empirically based on signs and symptoms. The peak incidence occurs in children between the ages of 2 and 4 years. REF: 393 OBJ: Level 2: Interpretation 7. What Haemophilus species is called the Koch-Weeks bacillus? a. H. influenzae b. H. parainfluenzae c. H. aegyptius d. H. aphrophilus C H. aegyptius (Koch-Weeks bacillus) is genetically related to H. influenzae. H. aegyptius was observed in conjunctivitis exudates from Egyptians by Koch in 1883, hence the species name. REF: 393 OBJ: Level 1: Recall 8. What organism causes Brazilian purpuric fever (BPF)? a. Haemophilus parainfluenzae b. H. aphrophilus c. H. aegyptius d. H. influenzae biogroup aegyptius D Despite being nonencapsulated, H. influenzae biogroup aegyptius causes a severe systemic disease known as Brazilian purpuric fever (BPF) in hot climates. REF: 394 OBJ: Level 1: Recall 9. What medium will sustain the growth of most Haemophilus spp.? a. Chocolate agar b. SBA c. PEA d. Thayer-Martin A When attempting to isolate most Haemophilus spp., chocolate agar is a commonly used medium incubated at 35 C in an atmosphere of 5% to 10% carbon dioxide. REF: 394 OBJ: Level 1: Recall 10. A microbiologist is reading a sputum culture and notices that there is no growth on the sheep blood and MacConkey agars, but there is growth on the chocolate plate. The colonies on the plate are translucent, moist, smooth, and convex, with a mousy odor. What is the most likely identification of the organism? a. Haemophilus parainfluenzae b. H. influenzae c. H. aegyptius d. H. ducreyi B Usually sheep blood agar, chocolate agar, and MacConkey agar plates are inoculated simultaneously from clinical specimens from areas of the human body where Haemophilus organisms may be isolated. Colonies of H. influenzae on chocolate agar appear translucent, tannish, moist, smooth, and convex, with a distinct “mousy, mouse nest,” or “bleachlike” odor. REF: 395 OBJ: Level 3: Synthesis 11. Which species of Haemophilus requires both X and V factors? a. H. parainfluenzae b. H. aphrophilus c. H. influenzae d. H. paraphrophilus C H. influenzae requires both X and V factors. H. parainfluenzae requires factor V only. H. aphrophilus requires factor X only. REF: 396 OBJ: Level 1: Recall 12. What is the drug of choice for treating a life-threatening illness caused by H. influenzae? a. Penicillin b. Macrolides c. Aminoglycosides d. Ceftriaxone D The current recommended treatment of life-threatening illness caused by H. influenzae is cefotaxime or ceftriaxone. Alternative drugs include trimethoprim-sulfamethoxazole, imipenem, and ciprofloxacin. REF: 397 OBJ: Level 1: Recall 13. The HACEK group includes all of the following except: a. Haemophilus spp. b. Aggregatibacter actinomycetemcomitans. c. Cardiobacterium hominis. d. Clostridium difficile. D HACEK is an acronym consisting of the first initial of each genus represented in the group: Haemophilus spp. especially H. aphrophilus, Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella sp. REF: 397 OBJ: Level 1: Recall 14. What organisms often are involved in septicemia in the granulocytopenic patient? a. Capnocytophaga spp. b. Eikenella corrodens c. Kingella spp. d. Fusobacterium spp. A Unlike the members of the HACEK group, Capnocytophaga spp. are not commonly involved in endocarditis as they are in septicemia in the granulocytopenic patient. REF: 402 OBJ: Level 2: Interpretation 15. All of the following are normal inhabitants of the human oral cavity except Capnocytophaga: a. fusofurium. b. gingivalis. c. ochracea. d. haemolyticus. A The five normal inhabitants of the human oral cavity, C. ochracea (DF-1), C. gingivalis, C. sputigena, C. haemolyticus, and C. granulosa, are all oxidase and catalase negative. REF: 403 OBJ: Level 1: Recall 16. What organism is likely to cause an infection after a cat bite? a. Campylobacter spp. b. Dysgonomonas capnocytophagoides c. Francisella tularensis d. Pasteurella spp. D Pasteurellosis, infection with Pasteurella spp., is a zoonosis—a disease that humans acquire from exposure to infected animals or products made from infected animals. Although Pasteurella infections can result from a variety of animal bites, they often occur as the result of feline bites. REF: 403 OBJ: Level 1: Recall 17. What is the most frequently isolated Pasteurella species? a. P. multocida b. P. septica c. P. gallicida d. P. canis A P. multocida is the most frequently isolated species and includes three subspecies: multocida, septica, and gallicida. REF: 403 OBJ: Level 1: Recall 18. All the following organisms are associated with human illness except: a. Brucella melitensis. b. B. ovis. c. B. suis. d. B. canis. B The four species that are most commonly associated with human illness are B. melitensis, B. abortus, B. suis, and B. canis. REF: 404 OBJ: Level 1: Recall 19. What is the name of the organism that causes tularemia, which can be contracted from rabbits? a. Brucella tularensis b. B. hareis c. Francisella tularensis d. F. philomiragia C Tularemia, infection with bacteria from the genus Francisella, is also a zoonotic disease and has many other names, including rabbit, deerfly, and lemming fever and water rat trappers’ disease. Tularemia can be contracted through ingestion, inhalation, arthropod bite (e.g., ticks and biting flies), or contact with infected tissues. REF: 406 OBJ: Level 1: Recall 20. What are the names of the two diseases caused by Legionella species? a. Rabbit fever and Pontiac fever b. Scalded skin syndrome and Legionnaires disease c. Malta fever and undulating fever d. Legionnaires disease and Pontiac fever D Clinical manifestations of Legionella infections include febrile disease with pneumonia (Legionnaires disease), febrile disease without pulmonary involvement (Pontiac fever), and asymptomatic infection. REF: 410 OBJ: Level 1: Recall 21. What organism produces a community-acquired pneumonia, with symptoms different than a Streptococcus pneumonia infection, leading to the designation of atypical pneumonia? a. Legionella pneumophila b. Mycoplasma c. Chlamydophila asteroides d. C. trachomatis A Pneumonia is the predominant manifestation of Legionella disease, and the organisms are among the top four causes of community-acquired bacterial pneumonia. Mycoplasma pneumoniae, Chlamydophila (chlamydia) pneumoniae, and Legionella produce symptoms different from S. pneumoniae and cause a disease sometimes referred to as atypical pneumonia. REF: 410 OBJ: Level 2: Interpretation 22. What medium is used to isolate Legionella? a. MacConkey b. BCYE c. Chocolate d. Bordet-Gengou B Legionella spp. are fastidious, aerobic bacteria that are unable to grow on SBA and require the amino acid L-cysteine for growth. However, buffered charcoal yeast extract (BCYE) agar is the recommended medium for Legionella isolation and is available commercially as nonselective and semiselective media. REF: 411 OBJ: Level 1: Recall 23. All of the following are rapid methods used to definitively identify Legionella species except: a. direct fluorescent antibody (DFA). b. DNA detection. c. indirect immunofluorescence. d. urine antigen testing. C The three rapid methods for identifying Legionella isolates that are approved by the Food and Drug Administration (FDA) include DFA, DNA detection, and urine antigen testing. REF: 409 OBJ: Level 1: Recall 24. What is the drug of choice for treating a Legionella infection? a. Aminoglycosides b. Penicillin c. Vancomycin d. Azithromycin D Susceptibility testing of Legionella spp. is not standardized or routinely performed. When infections are diagnosed early, they can usually be treated successfully with a macrolide, such as azithromycin or a fluoroquinolone. This is particularly important in nosocomial infections, because they usually involve compromised patients and the disease often takes an aggressive course. An alternate drug is doxycycline. REF: 414 OBJ: Level 1: Recall 25. What organism causes the disease called whooping cough? a. Bordetella pertussis b. Legionella pneumoniae c. Mycoplasma pneumoniae d. Chlamydophila pneumoniae A Both B. pertussis and B. parapertussis are primary human pathogens of the respiratory tract, causing whooping cough or pertussis, although the latter organism is usually associated with a milder form of the disease. REF: 415 OBJ: Level 1: Recall 26. What agar is used to isolate the Bordetella species? a. BCYE b. Bordet-Gengou c. Chocolate d. Martin-Lewis B Since the original development of Bordet-Gengou potato infusion agar with glycerol and horse or sheep blood, few alternative formulations have been as successful. Plates for the recovery of Bordetella species should be incubated at 35 C in ambient air for a minimum of 7 days. REF: 417 OBJ: Level 1: Recall 27. How is Bordetella disease spread? a. Fomites b. Contaminated food c. Respiratory droplet d. Airborne C Pertussis is a human disease. No known animal reservoir or vector has been found. Infections caused by Bordetella spp. are acquired through the respiratory tract via respiratory droplets or direct contact with infectious secretions. REF: 416 OBJ: Level 1: Recall 28. What is the specimen of choice for Bordetella species? a. Throat cultures b. Sputum specimens c. Bronchial aspirations d. Nasopharyngeal swabs D Nasopharyngeal aspirates or swabs (calcium alginate or Dacron polyester with a flexible wire shaft) are the specimens of choice for culture, DFA, and polymerase chain reaction (PCR) testing for Bordetella. REF: 417 OBJ: Level 1: Recall 29. What is the drug of choice for treating Bordetella infections? a. Erythromycin b. Penicillin c. Aminoglycosides d. Quinolones A Although a few strains of erythromycin-resistant B. pertussis have been reported, erythromycin is still the drug of choice for treatment and prophylaxis of pertussis. REF: 419 OBJ: Level 1: Recall