Corynebacterium

Question 1

Also known as the diphtheria bacillus or Kleb-Loffler bacillus

Answer 1

C. diph

Question 2

It is not part of the indigenous microbiota of the respiratory tract,
and only inhabits the human nasopharynx in a carrier state
o carrier state – harbors the bacteria but asymptomatic

Answer 2

C.diph

Question 3

It rarely enters the bloodstream

Answer 3

C.diph

Question 4

It is readily killed by heat and by most usual disinfectants
• It is a glucose and maltose fermenter

Answer 4

C.diph

Question 5

Preferred medium: Regular culture media enriched with
serum, cysteine, and potassium tellurite

Answer 5

C.diphth

Question 6

Its cells have rounded ends and “club-shaped sweiings”
o Its highly pleomorphic cells are arranged in pairs and
create X, V, Y and L formations that closely resembles
Chinese letters

Answer 6

C,diph

Question 7

Biochemical tests: (-) Urease, (+) nitrate reduction

Answer 7

C.diph

Question 8

Best specimens: Nasopharyngeal and throat swabs

Answer 8

C.diph

Question 9

Toxin: It favors an alkaline pH (7.8-8.0), an aerobic
environment, and sufficient amount of iron in the
medium consumed

Answer 9

Diph toxin

Question 10

It causes tissue necrosis and exudate formations over
the tonsils, larynx and pharynx

Answer 10

C.diph: diph toxin

Question 11

t is an acute, infectious disease that is characterized by
the production of a systemic toxin and a false membrane
lining of the throat mucous membrane that may
eventually lead to respiratory obstruction

Answer 11

Respiratory diphtheria

Question 12

o Non-healing ulcers with dirty gray membrane
o Infection of the skin/non-respiratory sites

Answer 12

• Cutaneous or skin diphtheria (Veldt sore)

Question 13

Systemic infection affecting various organs
▪ Demyelinating peripheral neuritis
▪ Cardiac failure Systemic infection affecting various organs
▪ Demyelinating peripheral neuritis
▪ Cardiac failure

Answer 13

Cutaneous or skin diphtheria (Veldt sore)

Question 14

• It is one of the most frequently isolated and most clinically
significant Corynebacteria species

Answer 14

C. urea

Question 15

It is a urinary pathogen, a strict aerobe, and lipophilic

Answer 15

C.urea

Question 16

It does not ferment glucose and maltose

Answer 16

C.urea

Question 17

Microscopy: Arranged in V-shaped forms and palisades

Answer 17

C.urea

Question 18

Culture: BAP - Colonies are pinpoint, white, smooth, and are
non-hemolytic

Answer 18

C.urea

Question 19

Biochemical test: Rapid urease producer

Answer 19

C.urea

Question 20

It is an indigenous microbiota of the human nasopharynx
o indigenous microbiota
▪ normal inhabitants but limited population
▪ not easy to isolate

Answer 20

C.pseudo

Question 21

It causes respiratory infection, UTI, and cutaneous wound
infections in immunocompromised patient, such as those who
have AIDS

Answer 21

C.pseudo

Question 22

Microscopy: Cells are arranged in parallel rows or palisades
and do not exhibit any other characteristic “pleomorphism” that
is similar to other corynebacteria

Answer 22

C.pseudo

Question 23

Biochemical test: (+) Urease and nitrate production

Answer 23

C.pseudo

Question 24

It is a skin microbiota that is found in inguinal, axillary, and rectal
sites

Answer 24

Corynebacterium jeikeium

Question 25

It is an obligate aerobe and a multi-antibiotic resistant bacterium

Answer 25

C.jeikye

Question 26

It is isolated from immunocompromised individuals

Answer 26

C.jeik

Question 27

It is a common cause of diphtheroid prosthetic valve endocarditis in adults

Answer 27

C.jeik

Question 28

Microscopy: Pleomorphic, club-shaped, and arranged in V- shaped forms

Answer 28

C.jeik

Question 29

BAP - Colonies appear large when added with 1% Tween 80

Answer 29

C.jeik

Question 30

Biochemical test: (-) Urease and nitrate reduction.

Answer 30

C.jeik

Question 31

It is acquired through animal contact or ingestion of unpasteurized dairy products

Answer 31

C.ulcer

Question 32

It is also isolated from skin ulcers and exudative pharyngitis

Answer 32

C.ulcer

Question 33

• It is associated with diphtheria-like sore throats since a significant isolates have shown to produce a diphtheria-like toxin

Answer 33

C.ulcer

Question 34

BAP - Colonies have a narrow zone of Beta hemolysis o CTBA (Cysteine-Tellurite Blood Agar) - Colonies have a surrounding brown halo o Loeffler’s serum agar - Colonies exhibit growth

Answer 34

C.ulcer

Question 35

Biochemical test: (+) Urease and gelatinases, (-) nitrate reduction

Answer 35

C.ulcer

Question 36

It produces a dermonecrotic toxin that causes death of various cell types

Answer 36

C.pseudotuberculosis

Question 37

CTBA - Colonies exhibit a black color and are surrounded with a brown halo o BAP - Colonies are small and yellowish-white

Answer 37

C.pseudotuberculosis

Question 38

Biochemical test: (+) Urease (-) gelatinase

Answer 38

C.pseudotuberculosis

Question 39

Methylene blue staining: Bacterial cells exhibit a beaded formation

Answer 39

C.diph

Question 40

are used for staining metachromatic granule

Answer 40

Neisser’s and Albert’s stains

Question 41

staining method is composed mainly of either methylene blue or crystal violet

Answer 41

Neisser’s staining

Question 42

stain is composed of malachite green and toluidine

Answer 42

Albert’s stain

Question 43

It is the preferred medium for the isolation and identification of corynebacteria

Answer 43

Cytine tellutite blood agar (CTBA)

Question 44

The multiplication of corynebacteria occurs within the range of what degree celsius?

Answer 44

15°C to 40°C

Question 45

+) Result: Colonies of corynebacteria exhibit a black or brown color after 48 hrs of incubation

Answer 45

CTB

Question 46

It contains sheep blood, bovine serum, cysteine, and potassium tellurite

Answer 46

CTBA

Question 47

It is composed of sheep blood, cysteine, potassium tellurite, and sodium thiosulfate

Answer 47

Tindsdale agar

Question 48

gram-positive and urease negative with brown halo

Answer 48

C. diphtheriae

Question 49

It is useful for observing the microscopic morphology and metachromatic granules of C. diphtheriae

Answer 49

Loeffler’s serum agar

Question 50

▪ (+) Result: C. diphtheriae colonies exhibit a “poached-egg” appearance

Answer 50

o Loeffler’s serum agar

Question 51

The metachromatic granules of C. diphtheriae are called

Answer 51

“Babes-Ernst” bodies

Question 52

This is used to observe the urease production of C. uralyticum

Answer 52

Christensen urea slant

Question 53

In vitro diphtheria toxin detection using immunodiffusion

Answer 53

Elek’s Test

Question 54

Precipitin lines are observed - slant lines found in the junction where the growth of inoculum and filter paper meet

Answer 54

Elek’s Test

Question 55

All staph are Aerobic or facultative anaerobic except for

Answer 55

S. saccharolyticus