Gram positive rods

Question 1

Gram positive rods

Answer 1

1. Corynebacterium
2. Bacillus
3. Cutibacterium
4. Clostridium
5. Actinomyces
6. Nocardia
7. Listeria monocytogenes
8. Erysipelothrix rhusiopathiae
9. Gardnerella vaginalis
10. Lactobacillus
11. Bifidobacterium
12. Eubacterium

Question 2

Corynebacterium

Answer 2

Catalase positive
They are lipophilic so some species may grow better on BLOOD than choc

Small gram positive rods

Question 3

Lipophilic Corynebacterium spp.

Answer 3

C. jeikeium (wound infection)
C. urealyticum (UTI)
C. kroppenstedtii (mastitis)
C. kroppenstedtii (mastitis)
C. accolens
C. afermentans
C. tuberculostearicum
C. resistans
C. sputi
C. lipophiloflavum
C. macginleyi

Question 4

Which Corynebacterium spp causes UTI in immune-competent hosts?

Answer 4

C. urealyticum

Question 5

Which Corynebacterium spp causes wounds/abscesses in immune-competent hosts?

Answer 5

C. jeikeium

Question 6

Which Corynebacterium spp causes breast abscesses in immune-competent hosts?

Answer 6

C. kropenstedtii

Question 7

Which Corynebacterium spp causes ear infections in immune-competent hosts?

Answer 7

Corynebacterium otitidis

Question 8

Which Corynebacterium spp causes respiratory/cutaneous infections in immune-competent hosts?

Answer 8

Corynebacterium diptheria

Question 9

Why is it difficult to distinguish Corynebacterium from other flora and how to determine it is causing an infection?

Answer 9

It is a normal commensal, grows with other flora and multiple positive cultures or an abundance of Corynebacterium are required to establish it as the disease causative agent

Question 10

Diseases caused by Corynebacterium in immune-compromised hosts? (3)

Answer 10

1. CLABSI- central line bloodstream infection due to central venous catheters
2. CSF shunt or drain infection (could be a contaminant, since it is a skin commensal)
3. Respiratory tract infections

Question 11

Which Corynebacterium causes diphtheria?

Answer 11

C. diphtheriae

rarely by C. ulcerans/C. pseudotuberculosis

Question 12

Diphtheria symptoms

Answer 12

spread by respiratory droplets (very contagious)

toxin mediated

pseudo membrane on throat

causes sore throat, fever, swelling of lymph nodes, may affect swallowing

Complications: difficulty breathing, myocarditis, nerve damage, kidney failure

Question 13

Which media selects for C. diphtheriae? (3)

Answer 13

Löffler agar
Cystine tellurite blood agar
Tinsdale agar

Question 14

Name of the test for diphtheria toxin?

Answer 14

ELEK test (only performed in public health labs)

immunodiffusion test

There is a filter paper with diphtheria antitoxin, immunoprecipitation appears if the strain carries the toxin

Question 15

Bacillus
Paenibacillus
Geobacillus

Answer 15

large colonies.
Beta hemolytic (except B. anthracis)
Catalase positive

Question 16

Bacillus cereus

Answer 16

toxin-mediated food poisoning (organisms not isolated, only stool)

Associated with contaminated wounds, eye infections, IVDU, and neonates

may cause systemic disease in the immune compromised

Question 17

Actinomyces spp.

Answer 17

molar tooth colonies, branching or rods, not acid fast

usually cause abscess with purulent exudate (pus) in head and neck regions

Also associated with IUD pelvic infections (usually normal flora, but in large quantities may cause disease)

associated with poor dental hygiene

abscess contain bacteria aggregates termed “sulfur granules”

Question 18

Nocardia

Answer 18

Look like Actinomyces, but these are modified acid fast positive

Grow on Löwenstein-Jensen (LJ) medium

distributed in water, soil, dust, and decaying vegetation
(not a commensal)

causes disease in immunosuppressed: skin, lungs, or brain

Question 19

Erysipelothrix rhusiopathiae​

Answer 19

Gram positive rod, but may decolorize

may cause swine erysipelas (erysipeloid rash/cellulitis) in people who work with farm animals

Rash is very faint and localized (looks like red scratches)

this might cause endocarditis and acute septicaemic disease in immunocompromised people

Rash is very faint and localized (looks like red scratches)

Question 20

Listeria monocytogenes

Answer 20

Foodborne pathogen that survives refrigeration temperatures

found in dairy products, vegetables, and cooked meats:
queso fresco, milk, ice cream, lunch meat

may spread hematogenously to:
1. liver (pyogranulomatous hepatosplenitis)
2. brain (meningitis) neonates and older adult patients
3. bloodstream (bacteremia)
4. placenta (may cause stillborth or neonatal infection)