Aerobic Gram Positive Bacilli Flashcards
Non-sporeforming
Catalase pos
Room temp motility neg
Esculin neg
What is the bacteria?
Corynebacterium sp.
Normal flora; typically a contaminant; affects immune compromised; diphtheria; endocarditis, urinary infections
What type of bacteria is this?
Corynebacterium sp.
Respiratory or cutaneous disease. Not common bc of vaccine. Grows best on enriched media
Corynebacterium diphtheriae
Associated with catheters and prosthetics
Corynebacterium jeikeium
Urinary pathogen; kidney stone formation; 48 hrs to grow on SBA; ID aided with rapid urease
Corynebacterium urealyticum
Non-sporeforming
Catalase neg
Reverse CAMP pos
Beta-hemolysis pos
What type of bacteria is this?
Arcanobacterium haemolyticum
Pharyngitis in 10-20 year olds; desquamation of skin; rash begins on extremities and spreads centrally
Arcanobacterium haemolyticum
Small colonies; may “pit” agar; small zones of B-hemolysis
Arcanobacterium haemolyticum
Small and dry; large and creamy colonies on agar
Corynebacterium sp.
What shape is Corynebacterium sp. on gram stain?
Club shaped
Non-sporeforming
Catalase pos
Room temp motility pos
Esculin pos
Hippurate hydrolysis pos
CAMP pos (box shaped enhancement)
Listeria monocytogenes
Disease in pregnant women (3rd trimester); newborn affected; GI infection in healthy people caused from contaminated foods
Listeria monocytogenes
B-hemolytic on SBA, often confused with Strep. algalactiae
Listeria monocytogenes
What foods can Listeria monocytogenes be found in?
Processed meats
Unpasteurized milk
Cheese
Deli salads
Uncooked meat
Veggies
Where is Listeria monocytogenes isolated from? (Samples)
Blood, CSF, Lesions
What pattern does motility for Listeria monocytogenes make in a semisolid media?
Umbrella pattern
Non-sporeforming
Catalase neg
Alpha/Gamma hemolysis pos
Non-motile
What bacteria is this?
Lactobacillus spp.
Normal flora in mouth, GI tract, girl genital tract, skin
Lactobacillus spp.
Overgrowth of other vaginal flora
Bacterial vaginosis
Pleomorphic shapes on gram stain for this type of bacteria.
Lactobacillus spp.
Pinpoint grey or Alpha-hemolytic colonies on SBA
Lactobacillus spp.
What kind of bacteria is a probiotic found in yogurt?
Lactobacillus spp.
Corynebacterium sp. is an aerobic gram pos rod. What is another term(s) it can be called?
Facultative anaerobe
Lactobacillus spp. is an aerobic gram pos rod. What is another term(s) it can be called?
Aerotolerant anaerobe
Spore-forming
Catalase pos
Oxidase pos (weak)
Beta-hemolysis pos
Motility pos (slow)
What type of bacteria is this?
Bacillus sp.
Skin flora, may cause infection; contains endospores that are infectious and germinates in host
Bacillus sp.
Large gram pos rod that is sporeforming
Bacillus sp.
Most are B-hemolytic; “ground glass” appearance (bumpy)
Bacillus sp.
Most clinically seen clinical isolate; typically a contaminant
Bacillus cerus
Sporeforming
Catalase pos
Oxidase pos (weak)
Beta-hemolysis neg
Motility neg
What bacteria is this?
Bacillus anthracis
Agent of anthrax disease, associated with cattle; Cutaneous, pulmonary, gastrointestinal disease; worry of bioterror attack
Bacillus anthracis
Gram stain shows palisading spores. What bacteria is this?
Bacillus anthracis
Non-hemolytic on SBA and a colony stands up when touched with a loop
Bacillus anthracis
If Bacillus anthracis is suspected, what should be your next steps?
Work in a Biosafety cabinet at all times; you may have to send it to a reference lab for ID
Produces H2S in TSI agar
Non-motile
“Brush-like” growth in gelatin slant
What bacteria is this?
Erysipelothrix rhusiopathiae
Infections from cut or abrasion of skin; rarely isolated in humans; reservoir is from domestic cows; septicemia (blood infection), endocarditis (heart inflammation), erysipeloid (wound infection)
Erysipelothrix rhusiopathiae
Gram stain shows GPR that are pleomorphic, and could form long filaments
Erysipelothrix rhusiopathiae
Catalase neg
Oxidase neg
Hippurate hydrolysis pos
What bacteria is this?
Gardnerella vaginalis
Associated with bacterial vaginosis
Gardnerella vaginalis
Gram stain shows short, pleomorphic, coccobacillus. You could stain gram variable or gram neg
Gardnerella vaginalis
Grows in SBA and CHOC; grows with increased CO2; pinpoint colonies at 24-48 hours
Gardnerella vaginalis
Name all the bacterias studied in the section that are Aerobic Gram positive Rods/Bacilli.
Corynebacterium sp. (diphtheriae, jeikeium, urealyticum)
Arcanobacterium haemolyticum
Listeria monocytogenes
Lactobacillus spp.
Bacillus sp. (Cerus, anthracis)
Erysipelothrix rhusiopathiae
Gardnerella vaginalis
An isolate with the appropriate colony and microscopic morphology may be suspected to be Bacillus anthracis if it is:
a. beta-hemolytic on SBA
b. nonmotile
c. catalase-negative
d. Gram negative, non-spore forming
b. non-motile
An aerobic, gram positive, spore-forming bacillus was isolated from raw vegetables that were associated with an outbreak of gastroenteritis. The organism produced beta-hemolysis, was catalase positive, and was motile. The most likely organism is:
a. Bacillus anthracis
b. Nocardia asteroides
c. Bacillus cereus
d. Tsukamurella spp.
C. Bacillus cereus
Bacillus cereus is most noted for causing:
a. food poisoning
b. meningitis
c. STD
d. UTI
a. food poisoning
Which forms of infection are caused by Bacillus anthracis?
a. injectional
b. inhalation
c. gastrointestinal
d. cutaneous
e. all of the above
e. all of the above
Corynebacterium species often appear as ______ on gram stain.
a. pleomorphic gram positive club-shaped bacilli that appear in palisades or in V and L formations
b. branching gram positive bacilli that appear as fine, intertwining, delicate filaments
c. short, thin gram positive bacilli that appear in chains
d. large square-ended, gram positive bacilli or gram variable bacilli in chains where the ends of the single cells fit snugly together
a. pleomorphic gram positive club-shaped bacilli that appear in palisades or in V and L formations
The biochemical tests performed on a gram positive bacillus were consistent with Corynebacterium diptheriae. As a definitive test, the laboratory scientist should now:
a. perform an Elek test to determine whether the organism produces exotoxin
b. subculture the organism to cystine-tellurite agar and examine for black colonies
c. prepare a methylene blue stain and examine for metachromatic granules
d. gram stain the isolate and observe for its pleomorphic morphology
a. perform an Elek test to determine whether the organism produces exotoxin
Diphtheria is not common in the US because:
a. The insect vector has been eliminated
b. Of vaccination of the animal reservoir
c. Of routine use of an effective human vaccine
d. Aggressive antimicrobial therapy has nearly eliminated the bacteria
c. Of routine use of an effective human vaccine
True infections with nondiphtheria Corynebacterium spp., such as C. jeikeium or C. striatum, are often in immunocompromised patients or patients who have had:
a. insertion of hardware or prosthetic devices
b. coronary artery bypass surgery
c. vitamin B12 deficiency
d. a lengthy hospital stay
a. insertion of hardware or prosthetic devices
A _____ test can help to differentiate which clinically significant Corynebacterium spp. recovered from urine samples?
a. gelatin hydrolysis; C. ulcerans
b. reverse CAMP; C pseudotuberculosis
c. alkaline phosphatase; C amycolatum
d. Urease; C. urealyticum
d. Urease; C. urealyticum
A newborn girl becomes febrile and will not feed about an hour after birth. A gram positive rod is recovered from blood cultures from the newborn. The isolate has the characteristics listed. What is the most likely the identity of the isolate?
Weakly beta-hemolytic on SBA, gram positive bacilli, no spores, catalase positive, hydrogen sulfide negative, motile at room temp
a. Erysipelothrix rhusiopathiae
b. Listeria monocytogenes
c. Corynebacterium ureilyticum
d. Gardnerella vaginalis
b. Listeria monocytogenes
A commercial fisherman who had red sores on his hands was seen by his physician. Biopsy and culture of one of the lesions was performed. The culture grew an organism with the characteristics listed. What is the most likely organism?
Nonhemolytic on SBA, gram positive bacilli, no spores, catalase negative, hydrogen sulfide positive, growth in gelatin resembled a test-tube brush
a. Rhodococcus equi
b. Listeria monocytogenes
c. Lactobacillus acidophilus
d. Erysipelothrix rhusiopathiae
d. Erysipelothrix rhusiopathiae
What other organisms can give similar clinical and laboratory findings as Listeria monocytogenes? How are these organisms differentiated from L. monocytogenes?
Streptococcus agalactiae (group B strep) and Enterococcus spp. can produce clinical lab findings similar to those for L. monocytogenes. Initial differentiation between L. monocytogenes and similar microorganisms can be made by the gram stain, catalase test, and esculin hydrolysis.
A 17-year-old boy presented to an emergency department with a history of multiple episodes of febrile pharyngitis followed in 10-14 days with extensive desquamation of his hands and feet. The reoccurrences have followed several courses of antimicrobial therapy including amoxillin and cephalosporins. Rapid group A streptococci screens and cultures have been consistently negative for Streptococcus pyogenes. A specimen with a request for an alternative agent was submitted to a reference laboratory. The results listed were observed. The patient was subsequently treated with erythromycin, and he recovered. What was the etiologic agent?
SBA: dry, wrinkled, slightly hemolytic colony, which at 48 hours is a dark spot sunken in the agar
Catalase (-)
Nitrate (-)
Reverse-CAMP-test (+)
a. Corynebacterium diphtheriae
b. Arcanobacterium haemolyticum
c. Listeria monocytogenes
d. Rhodococcus equi
b. Arcanobacterium haemolyticum
