
Kingdom: Prokaryotae ( 原核生物界 )
1.
Cells have no distinct nucleus / no nuclear envelope
2.
Single circular DNA molecule in cytoplasm
3.
Membranous organelles absent
4.
Infolding of the cell membrane forms mesosomes for respiration

Mode of nutrition
 Photosynthetic – cyanobacteria

Chemosynthetic – nitrogen-fixing bacteria
 Saprophytic – putrefying bacteria

Parasitic – pathogenic bacteria
 Oxygen demand

Aerobes – bacteria require oxygen for respiration
 Anaerobic – bacteria unable to tolerate oxygen

Facultative anaerobes – can grow with or without


Gram stain reaction oxygen)

Bacteria can be categorized based on the cell wall
 structures which in turn influences the Gram stain
 reaction.

Gram –ve : appears pink after staining

Gram +ve : appears purple after staining


1.Anthrax
炭疽病

2.Tuberculosis (TB) 肺結核 / 肺癆

3.Cholera 霍亂

4.Diphtheria 白喉

5.Syphilis 梅毒 (STD)

6. Gonorrhea 淋病 (STD)

7. Leprosy 痲瘋

8.Plague 瘟疫 / 黑死病 / 鼠疫

9.Tetanus 破傷風

10.Typhoid 傷寒

11.Typhus 斑疹傷寒

- - in gastrointestinal (GI) tract and colon
S synthesis of vitamin K
In immunosuppressed host, even nonpathogenic strains can cause infection
Diarrhoea

Anthrax 炭疽病 – caused by spore-forming
Bacillus anthracis

- occur in humans when they are exposed to infected animals or to tissue from infected animals or when anthrax spores are used as a bioterrorist weapon.

- will not transmit from person to person

- the spores can be used as a bioterroist weapon,
 as was the case in 2001, when the spores had been intentionally distributed through the postal system, causing 22 cases of anthrax, including 5 deaths

Bacillus anthracis ,
Gram stain
Anthrax skin lesion

Tuberculosis (TB) 肺結核 / 肺癆 - caused by rod-shaped Mycobacterium tuberculosis
Tuberculosis creates cavities visible in x-rays like this one in the patient's right upper lobe.
- chronic or acute bacterial infection that primarily attacks the lungs
- transmitted by inhaling bacteria-carrying droplets drug resistant strains developed

破傷風

- bacteria on rusty nails

- release exotoxin

- serious infections disease to the nervous system

- lockjaw, stiffness of abdominal and back muscles , facial muscle spasms, fast pulse, slight fever, severe sweating ,headache

真菌界
- eukaryotic, heterotrophic organisms that have rigid cellulose- or chitin-based cell walls
- unicellular e.g. yeast or multicellular
- saprophytic fungi – decomposer parasitic fungi – pathogenic
- may be opportunistic

Yeast invade internal tissues :
Fungi that are external parasites of humans:
Ringworm, athlete’s foot
Ringworm
Athlete’s foot

Protozoa 原生動物
Kingdom – protoctista 原生生物界
 Ｍ alaria 瘧疾 － by Plasmodium
- transmitted by bite of female mosquitoes
Trypanosomiasis 昏睡病 by Trypanosoma

Other pathogens
(not microorganisms)

Parasitic worms
Wuchereria bancrofti
絲蟲 -> Elephantiasis 象皮腫

Transmission of infectious diseases
1. Through air or air-borne particles
2. Through contaminated food and water
3. Direct contact (including sexual)
4. Blood transfusion
5. Through body fluid
6. Though sharing infected tools
(needles)
7. Through sexual contact
8. Through vector