E.Rhusiopathiae, Corynebacterium, A.Hemolyticum, Lactobacillus, Nocardia

Question 1

What are the characteristics of E.Rhusiopathiae?

Answer 1

Gram positive rods forming long filaments
Facultative Anaerobe
Slow growth
Small gray colonies
Alpha hemolytic
Catalase Neg (differentiate from listeria)
Non-motile
WEak fermenter
Produce H2S on TSI (ONLY GRAM + PRODUCING H2S)

Question 2

What is the epidemiology of E.Rhusiopathiae?

Answer 2

Found in soil and groundwater worldwide
Uncommon disease in humans, more in animals
Humans acquire infection from animals

Question 3

What are the 2 forms of human infections of E.Rhusiopathiae?

Answer 3

Erysipeloid: localized skin infection on fingers or hands that spreads peripherally as discoloration fades

Septicemic: uncommon; if present associated with endocarditis

Question 4

How is E.Rhusiopathiae treated?

Answer 4

Penicillin

Question 5

What are the characteristics of Corynebacterium?

Answer 5

Gram Positive Rods
Resemble CHINESE LETTERS
Grows aerobic or facultatively anaerobic
Small white non-hemolytic colonies

Question 6

Where is Corynebacterium found?

Answer 6

Plants and animals

Question 7

What are the important species of corynebacterium?

Answer 7

C.Diptheriae

C.Jeikeium

Question 8

What are the characteristics of C.Diphtheriae?

Answer 8

Infection transmitted via respiratory droplets or direct contact with cutaneous infection

Causes Diphtheria
Rare in US due to immunization

Question 9

What is the form of vaccine for C.Diphtheriae?

Answer 9

Vaccinate with toxoid treated with formalin

REvaccinate every 10 years

Question 10

Describe the pathogenesis of C.Diphtheriae

Answer 10

Caused by potent exotoxin -> inhibits proteiin synthesis of cells

2 Subunits
A: inhibit protein synthesis
B: Binds cell receptor

Question 11

What makes C.Diphtheria virulent?

Answer 11

If it is infected with bacteriophage with the toxin gene

Question 12

What are the clinical presentations of a pt with diphtheria?

Answer 12

Pharyngitis with exudates on tonsiles, uvula, soft palate
Tough, gray pseudomembrane of fibrin, WBC, bacteria, debris

Can have cardiac injury if toxin travels to heart
Reversible paralysis if toxin gets to CNS

Question 13

How is Diptheria diagnosed?

Answer 13

Clinical Evaluation, no rapid lab test

Take throat swab for cultures to prove prsence of toxin

Question 14

How is Diptheria treated?

Answer 14

Antitoxin + Penicillin or Erythromycin

Question 15

What are the important characteristics of C.Jeikeium?

Answer 15

Infects immunocompromised patients
From blood cultures, catheter lines, skin
Resistant to most Abx EXCEPT VANCOMYCIN

Question 16

What are the characteristics of Arcanobacterium Hemolyticum?

Answer 16

Nonspore forming
Gram positive rod
Irregular curved formation
Catalase Negative
B-hemolytic

Question 17

Where is A.Hemolyticum isolated mostly from?

Answer 17

Young Adults symptomatic of pharyngitis, rash, fever, pseudomembranes in pharynx/tonsils and submandibular lymphadenopathy

Wounds, abscesses and blood of patients iwth septicemia and endocarditis

Question 18

What is A.Hemolyticum similar to on plates?

Answer 18

Group A Strep. But doesnt type wiht Group A Strep Anti-sera

Question 19

What are the characteristics of Lactobacillus

Answer 19

Gram Positive Rod
Non-spore forming
Prefers Anaerobic
Opportunistic Pathogen- sepsis, endocarditis

Question 20

Where is Lactobacillus normally found?

Answer 20

Yogurt

Oral Cavity, vaginal tract

Question 21

What are aerobic actinomycetes?

Answer 21

Aerobic Gram Positive Rods

Catalase Positive

Question 22

Where are Aerobic Actinomycets found?

Answer 22

Soil and decaying vegetation

Colonize animals and humans

Question 23

What is Nocardia?

Answer 23

Aerobic Actinomycetes

Question 24

What are the characteristics of Nocardia?

Answer 24

Gram Positive Rods
Partially Acid FAst 
Cell wall: MYCOLIC ACID
Strict AEROBE
Grows well on nonselective agars
Prolonged incubation time

Question 25

How does Nocardia look on gram stain?

Answer 25

Beaded rod appearance

Need to use acid fast stain because it doesn’t stain well

Question 26

How does Nocardia look on modified acid fast stain?

Answer 26

STains pink with similar appearance to gram stain

Question 27

How does nocardia infection occur?

Answer 27

Exogenous infection via inhalation or traumatic introduction (cutaneous)

Question 28

What are predisposing factors for nocardia infection?

Answer 28

Immunocompromised patients with chronic pulmonary disease or T cell deficiencies

Question 29

Why don’t we cell Nocardia with AIDS patients?

Answer 29

AIDS pts are given Bactrim prophylatically -> Nocardia is also prophylaxis with Bactrim

Would see if they didn’t take Bactrim

Question 30

What does Nocardia infection cause?

Answer 30

Bronchopulmonary Disease
Primary or 2ndary Cutaneous Infections
Secondary CNS Infections (ex: Brain Abscess)

Question 31

How are Nocardia infections treated?

Answer 31

Sulfonamides and proper wound care

Question 32

• A 22 year old medical student presents with symptoms
of pharyngitis with a fever, and cutaneous rash. A
throat culture reveals small beta hemolytic colonies
that are catalase-negative and stain as short Grampositive rods exhibiting Chinese character
morphology. What is the most likely agent of this
students pharyngitis?
A. Arcanobacterium hemolyticum
B. Corynebacterium diphtheriae
C. Erysipelothrix rhusiopathiae
D. Listeria monocytogenes
E. Streptococcus pyogene

Answer 32

b