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Gram positive bacilli


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AEROBIC gram positive bacilli genera (5)
listeria monocytogenes
erysipelothrix rhusiopathiae
Name 3 general characteristics of all Corynebacterium species:
(shape, behavior, test)
-Club-shaped GPB
-Capable of snapping/pallisading
-Catalase positive
What special staining morphology is unique to corynebacterium diptheriae?
-When stained w/ methylene blue, shows metachromatic food granules that LOOK like spores
What type of hemolysis does C. diptheriae exhibit?
Beta; therefore it could be confused with beta streps.
Name 2 types of growth media for culturing C. diptheriae:
-Loeffler serum agar

-Tellurite agar
Why is Loeffler serum agar used?
It allows for a good staining reaction of C. diptheriae
What is the purpose of tellurite agar?
Isolation & differentiation of C. diphtheriae.
Differentiation: C. dipht will turn black, other colonies will remain clear/white.
what causes diptheria?
exotoxin produced by the organism;

coded by lysogenic phage
List 3 symptoms of diptheria:
-pharyngeal membrane
how many types of corynebacterium, what are they:
-corynebacterium diptheriae
-diptheroids (12)
-Corynebacterium jeikeium
-corynebacterium urealyticum
when does diptheria develop from a corynebacterium diptheroid strain?
when a lysogenic phage (encoding the toxin that causes the disease) infects the bacterium.
symptoms of diptheria
swellign of neck, lymphadenopathy, Bull's Neck
3 strains of colonial morphology of corynebacterium on tellurite agar:
-gravis (very grave; severe)
-mitis (little mite; not severe)
-intermedius duh
what is the Elek test for?
confirming the virulence of corynebacerium diptheriae (make sure it actually is producing the toxin)
3 steps in the diagnostic strategy for corynebacterium diptheriae
1. doctor clues us in
2. colonial morphology on tellurite tells how virulent the strain is.
3. virulence testing (elek) confirms the virulence
What are the diptheroids?
Where are they normal flora?
A general group of about 12 corynebacterium species;

-Normal flora on skin/mucous memb/vagina;
What diphtheroid is most commonly an infection causer?
Where is it normal flora?
-Corynebacterium jeikeium

-Human skin
What is the DPT vaccine for?
Diphtheria and Pertussis - but should only be given to folks under 5 yrs old.
What bacteria causes encrusted cystitis?
Explain the infection.
C. urealyticum. It produces urease; surrounds itself w/ NH3 to combat antibiotic, results in a chronic UTI.
what is commonly inserted into the vagina to maintain its physiology because it's such a wonderful part of the normal flora?
lactobacillus. also common in mouth.
lactobacillus morphology
long, thin GPB
lactobacillus is it a pathogen?
rarely; in yogurt and probiotics. in the normal flora.
two things that differentiate corynebacterium from lactobacillus:
Coryne Lacto

Catalase positive Catalase negative
snapping no snapping
club-shaped long and thin
small/dry/white tiny/clear/alpha
beta alpha
listeria monocytogenes gram stain
gram positive COCCObacilli; very small so look for one
3 basic characterist of listeria:
1. gram stain = coccobacilli

2. weak positive catalase

3. weak B-hemolysis confuses w/ strep cuz its small/off-white/translucent too
pathogenicity of listeria; where, to whom, what diseases?
where; in dairy products, cold, processed meats like hot dogs.

whom: in neonates or immunocomp adults;

diseases: meningitis, septicemia
which organism is commonly confused with weakly B-hemolytic Streps?
listeria monocytogenes
what is commonly confused with listeria?
weakly B-hemolytic streps
How specifically is Listeria similar to Strep?
-Bile esculin positive makes you think it's enterococcus or strep D nonentero.

-Hippurate hydrolysis positive makes you think it's Strep group B
what are 2 ways to detect motility of listeria?
at room temp (cooler)

-hanging drop shows tumbling!!

-semi-solid stab shows umbrella!!
What weird combo is used to treat listeria?
amoxacillin + aminoglycoside
positive biochem tests of listeria;
bile esculin
hippurate hydrolysis
beta hemolysis

all are positive!
Name two basic characteristics of erysipelothrix rhusiopathiae:
-Long, gram pos bacilli

-Catalase negative
What type of disease does e. rhusiopathiae cause:
Erysipeloid - a zoonotic cellulitis in vets and butchers, that may turn to bacteremia.
H2S - Hydrogen sulfide positive
basic description of bacillus gram stain
large gram positive bacilli with spores
bacillus is catalase
listeria is catalase
weakly positive
erysipelothrix rhusiopathiae is catalase
corynebacterium is catalase
lactobacillus is catalase
all bacillus are ___ and ___ except Anthracis:
beta hemolytic

what is the pathogen of the bacilli?
bacillus anthracis
what bacteria makes chains of gpb with round to oval cntral spores? looks like bamboo?
bacillus anthracis
What does tenacious mean?
Colonies like to stick togehter
what chemically makes anthracis tenacious?
it has a protein capsule instead of glycocalyx/sugar. Thus it sticks
hemolysis of bacillus anthracis?
not beta like its family; its gamma!
which bacteria has a rhizoid margin
bacillus anthracis
what happens when you touch the top of an anthracis colony with a needle?
sticks to the needle like an egg-white peak cuz of the protein capsule in place of sugar
What are three pathogenic forms of anthracis?
What is the main cutaneous anthrax characteristic, and another name for this form?
Black escher - spores under the skin cause pustules which turn black.
How is cutaneous anthrax often transmitted?
Through handling goat hides
How is pulmonary anthrax transmitted?
What is another name for it?
Via inhalion of spores released during wool shearing.
Aka, Woolsorter's disease.
least common and most likely to be fatal anthrax form:
enteritis. From infected meat.
what is used to treat anthrax?
penicillin/ ciprofloxacin
6 essentials for I.D. Anthrax:
1. Gamma colonies
2. Large tenacious GPB with spores
3. Catalase +
4. Non-motile
5. I.D. by public health labs
6. Level 3 safety safety cab necessary
where are saprophytic bacilli often found?
as plate contaminants on cultures.
type of hemolysis of Saprophytic bacillus
Beta, like almost all other bacilli, except anthracis
bacillus cereus causes 2 TWO! really gross things:
-emetic food poisoning

-diarrhetic food poisoning
What are the 2 main differences between emetic and diarrhetic food poisoning?
The incubation times and associated foods.
-Emetic: 1-6 hr incubation, assoc. w/ fried rice. -Diarrhetic: 6-24 hr incubation, assoc. w/ meats and sauces.

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