Unit 3 Flashcards
What is the name of the group of bacteria that are gram-positive rods often referred to as club-shaped or V & L forms when viewed in a gram stain?
Corynebacterium
What is the major virulence factor associated with corynebacterium diphtheriae?
Diphtheria toxin
A young girl is brought to her physician by her mother, who says the child has been very sluggish with a fever of 38C (100.5F)for a week. The mother noticed that the child’s tonsils were red and that the previous day the back of her throat turned a gray color and looked to have a gray membrane on it. What disease should the physician suspect?
Diphtheria
What organisms displays Babes-Ernst granules on a gram stain?
Corynebacterium diphtheria
What media does corynebacterium diphtheria grow on?
All of the above
*sheep blood agar (SBA)
*Loeffler
*Cystine-tellurite blood
What test is performed to determine if corynebacterium diphtheria is a toxigenic stain of an organism?
Elek test
What corynebacterium species is commonly associated with hospitalized immunocompromised patients?
C. Jeikeium
What is one of the most frequently isolated, clinically significant corynebacteria associated with UTIs?
C. Urealyticum.
All of the following species of Acranbacterium are clinically significant, except
A. Urealyticum
What is the colony morphology of A. Haemolyticum on SBA?
A narrow zone of B-hemolysis and a black opaque dot is seen when the colony is scraped away
What organisms are describe are partially acid fast and diphtheroid gram-positive rods with traces of branching on a gram stain?
Rhodococcus equi
What organism is a member of the human oropharyngeal biota but has been isolated from people with endocarditis?
Rothia dentocariosa
What organism is responsible for spontaneous abortion and stillborn neonates, and can cause meningitis with a fatality rate approaching 50% is newborn?
Listeria monocytogenes
Several people from a picnic came down with GI disturbance, and public health officials suspected a case of food poisoning. The food was cultured, and after 24 hours of incubation the hot dogs yield growth on SBA on small, round, smooth gram-positive coccobacilli. Mortality medium was inoculated and an umbrella pattern of motility was observed at room temperature. What organism was isolated as the cause of illness?
Listeria monocytogenes
Erysipelothrix rhisopathiae produces all t h following diseases except
Meningitis
One of the foremost at a pig farm notices purple sores on one of his workers. The worker has not been feeling well for the past 2 weeks, so the foreman sends him to the physician. The physician takes scrapings from the lesions and sends them to the laboratory for a culture. The gram stain shows 3+ thin, gram-positive rods that have filaments. The culture plates were examined the next day and revealed nonhemolytic, pinpoint, transparent colonies. What is the most likely pathogen?
Erysipelothrix rhusiopathiae
What is the name of the bacterium that plays an important role in the health of the female vaginal tract, protecting it against pathogens?
Lactobacillus
All of the following are general characteristics of the genus Bacillus, except
Cocci
What is the name of the Bacillus sp. that causes anthrax in cattle?
B. Anthracis
What is the name of the organism that, before being identified as an important cause of infections is immunocompromised patients, was considered a common laboratory containment?
Bacillus subtilis
The three proteins that make up the anthrax toxin include all the following except
Cellular factor
How is anthrax spread in animals?
Eating plants contaminated with the spores
What form of anthrax is found amount animal workers and has been called woolsorter disease?
Inhalation
Which of the following would be considered a diphtheroid ? `
Corynebacterium sp.
The presence of gram-variable bacilli on the surface of epithelial cells collected from the vaginal mucosa indicates
Bacterial vaginosis
What disease is considered a complication of any from of anthrax (cutaneous, GI or inhalation?
Meningitis
What bacteria’s morphology is described as large, square-ended, gram-positive or gram-variable rods found singly on in in chains?
Bacillus anthracis
What bacterium produces colonies that are nonhemolytic, large, gray, and flat with an irregular margin on SBA?
Bacillus anthracis
All of the following tests should be performed by sentinel laboratories to rule out the possibility of Bacillus anthracis from an isolate except
Glucose fermentation
What are the confirmatory tests performed at a state laboratory for Bacillus anthracis?
Cell wall polysaccharide end a capsule antigen
What antibiotic, in 2000, was approved by US food and drug administration (FDA) for postexposure inhalation anthrax?
Ciprofloxacin
What Bacillus sp. is a relatively common cause of food poisoning and opportunistic infection in susceptible hosts?
Bacillus cereus
What other gram-positive rod is similar to bacillus anthracis morphologically and metabolically?`
B. Cereus
Which of the following is true about Nocardia spp.??
All of the above
* the organisms grow on strand are nonselective media
*growth may take a week or more
*infections occur in immunocompromised patients
All of the following are commonly encounter Nocardia spp. except
N. Transvalensis
What is the name of the iron-chelating compound by Nocardia spp?
Nocobactin
What is the name of the Nocardia sp. that most frequently causes a cutaneous infection? `
N. Brasíliensis
How can Nocardia spp. be presumptively identified?
Filamentous, branching organisms with a carbolfuchsin acid-fast stain with a weak acid decolonizer but not a kinyoun acid fast stain
What is it that although Nocardia spp. grow on most common nonselective laboratory media, many are missed when the cultures are read?
These organisms require 3-6 days to grow
Why is it important to differentiate infection with Nocardia spp. in pulmonary infections?/
All of the above
*antifungal agents do not kill organisms
*these organisms are resistant to penicillin
*these organisms are susceptible to sulfonamides
What is the name of the genus of organisms that are primarily Saprophytic and resemble aerobic actinomycetes with the morphology and disease they cause?
Streptomyces
What is the name of the genus whose members are called nocardioforms?
Gordonia
Colonies of Bacillus anthracis are described as
Medusa heads
The colonies of this organism form large, rough, greenish, hemolytic colonies on blood agar, what organism is it?
Bacillus cereus
Typically, all Neisseria spp. are all of the following except
Motile
To which category do most Neisseria spp. belong?
Capnophilic
Which of the following can be found as part of the commensal biota of the upper respiratory tract?
N. Meningitidis
Gonococcal infections occur primarily in all the following sites, except
Uterus
The virulence factors for Neisseria spp. include all of the following except
Exotoxin
How are Neisseria gonorrhoeae infections transmitted?
Sexual contact
What is the most common manifestations of Neisseria gonorrhoeae infection in men?
Purulent urethral discharge and dysuria
What does blood-borne dissemination of Neisseria gonorhoeae usually result in?
Purulent arthritis
If a female is symptomatic, what are the most common symptoms of Neisseria gonorrhoeae infection?
Cervical discharge and dysuria
What is a major cause of pelvic inflammatory disease in women?
Untreated Gonococcal cervicitis
What disease is most commonly associated with newborns passing through a birth canal infected with Neisseria gonorrhoeae?
Ophthalmia neonatorum
What is the specimen of choice in males for genital infections?
Purulent urethral discharge
How should a specimen for Neisseria gonorhoeae culture be transported to the Laboratory?
Placed in Amies with charcoal transport system and transported to the laboratory immediately
If a male is infected with Neisseria gonorrhoeae, what would be the results of a Gram stain of Purulent urethral discharge reveal?
Many polymorphonuclear WBCs, some with gram-negative intracellular diplococci and gram-negative diplococci
If a Gram stain of urethral discharge from a male has more than four polymorphonuclear leukocytes per field but no bacteria, what organism is suspected of causing the infection?
Chlamydia trachomatis
What type of swab of should be used for a Neisseria gonorrhoeae culture?
Dacron
Why do Thayer-Martin and Martin-Lewis media have antimicrobial agents added?
To prevent overgrowth of normal biota
Under what condition should the inoculated plates for Neisseria gonorrhoeae culture should be incubated?
35 C and 3-5% carbon dioxide
A microbiologist reading potential genital cultures on a Martin-Lewis plate should look for what colony morphology if Neisseria gonorhoeae is suspected?
Small, tan, translucent
An oxidative-positive, gram-negative diplococcus produces bubbles in 30% hydrogen peroxide. What is the organism?
N. Gonorrhoeae
Which of the following is characteristic of Moraxella catarrhalis?
Tributyrin positive
What antimicrobial agents are recommended for treatment of uncomplicated Gonococcal infections?
Cephalosporins
How is Neisseria meningitidis most commonly spread?
Respiratory droplets
The symptoms of meningococcal meningitis include all of the following, except
Backache
A young adult goes to the emergency department complaining of headache, dizziness, stiff neck, and purpura with a petechial skin rash. What two tests should the physician immediately perform>
Blood and CSF culture
What is the name of the condition in which there is hemorrhage in the adrenal glans?
Waterhouse-Friderichsen syndrome
A microbiologist does a Gram stain on a CSF. She sees intracellular and extracellular gram-negative diplococci. What is the most likely organism?
N. Sicca
What media should be used to isolate Neisseria meningitis from respiratory samples?”
Selective and nonselective
In carbohydrate substrate test, a gram-negative diplococcus produces acid only from glucose and maltose. You should suspect
N. Meningitidis
What organism is a commensal of the upper respiratory tract and has become an opportunistic pathogen causing upper and lower respiratory tract infections in otherwise healthy children and the older adults
Moraxella catarrhalis
nonpathogenic commensal Neisseria spp. include all the following except
N. Menigitidis
All of the following are characteristics of haemophilus spp. except
Gram-positive cocci
Which species are associated with infection in humans?
All of the above
*Haemophilus influenzae
*H. Aegyptius
*H. Ducreyi
A microbiologist is reading a sputum culture and notices tiny, translucent colonies growing closely around a B-hemolytic colony on sheep blood agar (SBA). The colonies growing in the area where the blood has be hemolyzed. What is the probable identity of the organism that is growing closely to the B-hemolytic organism, ad why are they growing in the hemolyzed area?
Haemophilus spp., because they need the factor V in this area
Which one of the virulence factors associated with Haemophilus spp. plays the most significant role in the invasiveness of the organism?
Capsule
A mother brings her lethargic, feverish baby into the ER. The baby is diagnosed with meningitis, and the physician does a spinal tap. The CSF gram stain shows many tiny gram-negative rods. What is the most probable identification of this organisms?
Haemophilus influenzae
The bacterium is the causative agent of kennel cough in dogs and is occasionally associated with respiratory tract infections in humans
Bordetella bronchiseptica
What Haemophilus species is called the Koch-Weeks bacillus?
H. Aegyptius
What organisms causes Brazilian purpuric fever (BPF)?
H. Influenzae biogroup Aegyptius
What medium will sustain the growth of most Haemophilus spp?
Chocolate agar (CHOC)
A microbiologist is reading a sputum culture and notices that there is no growth on the sheep blood and MacConkey (MAC) agar plates, but there is heavy 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?
H. Influenzae
Which species of Haemophilus requires both X and V factors?
H. Influenzae
What is the drug of choice for treating a life-threatening illness caused by H. Influenzae?
Ceftriaxone
The HÁČEK group includes all of the following except
Clostridium difficile
What organisms often are involved in septicemia in the granulocytopenic patient?
Capnocytophaga spp.
What organisms often are involved in septicemia in the granulocytopenic patient?
Capnocytophaga spp.
All of the following are normal inhabitants of the human oral cavity except
Capnocytophaga fusofurium
What organism is likely to cause an infection after a cat bite?
Pasteurella spp.
What is the most frequently isolated pasteurella species?
P.multocida
All of the following organisms are associated with human illness, except
B. Ovis
What is the name of the organism that causes tularemia, which can be contracted from rabbits?
Francisella tularensis
What are the names of the two diseases caused by Legionella species?
Legionnaires disease and Pontiac fever
What organism produces a community-acquired pneumonia, with symptoms different than a streptococcus pneumoniae infection, leading to the designation of atypical pneumonia?
Legionella pneumophila
What medium is used to isolate legionella?
Buffered charcoal yeast extract (BCYE)
All of the following are rapid methods used to definitively ID legionella species except
Indirect immunofluorescence
What is the drug of choice for treating a legionella infection?
Macrolide
What organism causes the disease called whooping cough?
Bordetella pertussis
What agar is used to isolate Bordetella pertussis?
Bordet-Gengou
How is pertussis spread?
Respiratory droplets
What is the specimen of choice for Bordetella pertussis?
Nasopharyngeal swabs
What is the drug of choice for treating Bordetella pertussis infection?
Erythromycin
A technician is working the night shift and receives a CSF specimen on an infant. The technician makes a Gram stain of the spinal fluid, then reads the smear under the microscope. The report the technician sends to the physician reads as follows: “gram-negative bacillus, small and pleomorphic.” What bacteria are being implied as the infecting agent?
Haemophilus influenzae
A microbiologist is reading plates from a CSF culture. She notices that there is growth on CHOC, but no growth on SBA or MAC agar. The gram stain showed a gram-negative bacillus. What organism can this be?
Haemophilus influenzae
A microbiologist is reading the plates from a sputum culture. There is growth only on the chocolate plate. When the microbiologist takes off the lid of the culture plate, he notices a distinct “mousy” smell. What organism can this be ?
Haemophilus sp.
This organism is described as glistening, silver, and resembling a mercury droplet on media supplemented with horse blood
Bordetella pertussis
