1. Pathogenic Bacteria 4

2. Listeria Genus Listeria Ubiquitous named after Joseph Lister
Gram (+), rod-shaped, facultative anaerobic,
Non-spore forming, motile via peritrichous flagella
Catalase (+), Oxidase (-)
Weakly β-hemolytic
Phylum Firmicutes
Class Bacilli
Order Bacilliales (Bacillus, Staphylococcus)
Family Listeriaceae
Ubiquitous
Listeriosis
. Listeria monocytogenes
. Listeria ivanovii
. Listeria grayi

3. Listeria monocytognes
Listeria monocytogenes
Psychrotrophic : growth at 4°C ~ 37 °C
Growth at refrigeration temp.
Resistant to pH, heat, salt
Lipoteichoic acids in cell wall
Resemble LPS of Gram (-) in both structure and function
Intracellular parasite
Ability to survive and multiply in phagocytic cells
monocytes, macrophages, polymorphonuclear leukocytes
can become blood-borne (septicemic)
Can move within eukaryotic cells
can avoid antibody-mediated humoral immunity
Penetrate the endothelial layer of the placenta

4. Listeriosis Listeriosis Zoonosis
Most commonly caused by Listeria monocytogenes
Listeria ivanovii : mainly in ruminants, rarely in humans
Listeria grayi
Rare, potentially lethal food-borne illness
case-fatality rate of 20~30%
Immunocompromised, pregnant women, newborns, the elderly
Oral route : ingestion of contaminated food products
Penetrate the intestinal tract to cause systemic infections
Non-invasive infection : gastroenteritis
Invasive infection : central nervous system
bacteremia, sepsis

5. Non-invasiveness infection
febrile gastroenteritis (열성 장염)
healthy persons who have been severely infected
Invasiveness infection
Immunocompormised, newborns, the pregnant, the elderly
Infections of the central nervous system
meningitis, meningoencephalitis (수막뇌염),
brain abscess (뇌농양), cerebritis (뇌수염)
Bacteremia & Sepsis
Influenza-like symptoms usually precede
Gastrointestinal symptoms may precede
Pregnant woman
Intrauterine or cervical infections
→ spontaneous abortion or stillbirth
Transplacental or transvaginal infection (newborns)

6. Listeriosis in newborns
초기 발현형 감염증
transplacental infection (태반을 통한 감염)
granulomatosis infantiseptica (영아 패혈성 육아종증)
fatal if not treated immediately
후기 발현형 감염증
transvaginal infection
miningitis/meningoencephlitis with septicemia

7. Diagnosis Treatment Prevention Cold enrichment : psychrotrophic
β-hemolytic
CAMP test (+) : enhanced hemolysis with S. aureus
Treatment
Ampicillin (penicillin) alone or with Gentamycin
L. monocytogenes : Resistant to cephalosporin
Penicillin allergy : Erythromycin
Prevention
High-risk groups
avoid unpasteurized foods (milk products)

8. Erysipelothrix rhusiopathiae
Genus Erysipelothrix
Gram (+) : can be mistaken for Gram (-)
Type B cell wall
the peptide bridge is formed between amino acids at
positions 2 and 4 of adjacent peptide side-chains
(the vast majority of bacteria, between amino acids at
positions 3 and 4)
slender rod-shape
straight, or slightly curved, or long filamentous
singly, in V-shaped pairs, or in short chains
aerobic to facultatively anaerobic (microaerophilic)
catalase (-)
non-spore-forming, non-motile

9. Erysipelothrix rhusiopathiae
Primarily an animal pathogen
Erysipelas in animals (단독)
pig (swine erysipelas, “diamond skin disease”)
turkey, birds, sheep, fish, reptiles
Human :
Erysipeloid (유단독) : 전염성 피부염
Human erysipelas (단독) : by pyrogenous Streptococcus
Treatment & Prevention

10. Corynebacteria Corynebacteria (Coryne-form bacteria)
Coryne : Greek "knotted rod" , “club”
Pleomorhic : irregular morphology (다형성)
rod-shaped (straight or slightly curved)
Snapping fission : V-shaped
Gram (+) with high G+C content
Corynebacterium, Brevibacterium, Arcanobacterium
Micrococcus, Rothia, …
Widely distributed in nature
Industrially important :
amino acids, nucleotides, enzymes
bioconversion of steroids, degradation of hydrocarbons

11. Corynebacterium Human pathogens Genus Corynebacterium Gram (+)
distinctive cell wall : mycolyl-AG-peptidoglycan (mAGP)
corynemycolic acid, arabinogalactan
pleomorphic
Catalase (+), aerobic or facultatively anaerobic
nonspore-forming, nonmotile
Metachromatic granule (이염성 과립) : stored phosphate
Industrially important :
Corynebacterium glutamicum : Glutamic acid (MSG)
Human pathogens
Corynebacterium diphtheriae
Diphtheroid : nonpathogenic Corynebacterium

12. Diphtheria Diphtheria Greek ‘diphthera’ leather
Corynebacterium diphtheriae
virulent & toxigenic strains are lysogenic (β prophage)
Acute and contagious infection
by direct contact or through the air
by contaminated objects.
Rare in the developed world due to widespread vaccination
Intoxication : diphtheria toxin
Laryngeal diphtheria (호흡기 디프테리아)
Cutaneous diphtheria (피부 디프테리아)

13. Laryngeal diphtheria Cutaneous diphtheria Latent period : 2~4 days
Begin with a sore throat and fever
Airway blockage : swollen throat, barking cough
grey or white pseudomembrane (위막) in the throat
lymph nodes in the neck may swell
barking cough “diphtheritic croup” (가막성 후두염)
Complications ;
myocarditis (심근염, abnormal heart rate)
inflammation of nerves (paralysis),
kidney problems
bleeding problems due to low blood platelets
Cutaneous diphtheria
skin, eyes, or genitals

14. Diphtheria toxin Diphtheria toxin Lysogenic conversion : β phage
Exotoxin :
A-B toxin : subunits A & B held together by a disulfide bond
Highly immunogenic : antitoxin (항독소)
Fragment A
Inhibition of protein synthesis
Inhibition is reversed by high doses of nicotinamide
Fragment B
Recognition subunit that gains toxin entry into host cell
by endocytosis
Binding to the cell surface of the B subunit (the less
stable) allows the A subunit (the more stable) to
penetrate the host cell

15. Vaccine Vaccine Diphtheria toxoid
DPT, DPaT, TdaP : with tetanus & pertussis vaccine
Quinvaxem : pentavalent vaccine
diphtheria, tetanus, pertussis (whooping cough),
hepatitis B, Haemophilus influenzae type b
Further doses are recommended every ten years.
Moloney test
to detect a high degree of sensitivity to diphtheria toxoid
intradermal injection of diluted toxoid
Previous infection may not prevent against future infection

16. Treatment Treatment Antitoxin serum (항독소 혈청)
Cannot neutralize toxin that is already bound to tissues
Serum sickness (혈청병) : horse serum
Antibiotic
Metronidazole, Erythromycin, Penicillin G
Penicillin G/Erythromycin Allergy: rifampin or clindamycin
Intubation (삽관) or Tracheotomy (기관절개)
open the airway in severe cases

17. Identification Tellurite Blood Agar
Selective medium for Corynebacterium species
C. diphtheriae reduces potassium tellurite to tellurium and
produce gray-black colored colonies
Elek’s test
immuno diffusion technique
in vitro test for toxigenicity of C. diphtheriae

18. Pathogenic Corynebacterium
Corynebacterium jeikeium
Corynebacteirum urealyticum
Corynebacterium amycolatum
Corynebacterium pseudotuberculosis
Corynebacterium ulcerans