What does a pathogen have to do? Infect (infest) a host Reproduce(replicate) itself Ensure that its progeny are transmitted to another host

Medical Virology Dept. of Medical Microbiology and Parasitology Shanghai Second Medical University Shanghai, China. E.mail:(xkguoshsmu.edu.cn)

Spirochetes Gram negative Long, thin, helical, motile axial filaments locomotion between peptidoglycan layer/outer membrane runs parallel

Biological Features Structure and chemical composition Developmental cycle Staining properties Antigens Growth and metabolism Characteristics of host-parasite- relationship Classification

Mycoplasmas a group of the smallest organisms that can be free living in nature, Pass bacterial filter and also grow on laboratory media. More than 80 species, belong to Mycoplasmatales of mollicute. 3 families can be divided:

Campylobacter Among the most widespread cause of infection in the world Cause both diarrheal and systemic diseases Campylobacter jejuni

General introduction Gram-negative, obligate intracellular coccobacilli bacteria that infect mammals and arthropods Rickettsiae are transmitted in the arthropods, which serves as both vector and reservior Both dna and rna Is sensitive to antibiotic

Biological Features Aerobic, Gram, noncapsulated, rods Gray-black colonies on tellurite亚碲酸盐 medium o Metachromatic granules Chinese-letter morphology in Gram stain

Actinomyces Israelii Anaeslundii a Gram positive sulfur granule; Related to decay tooth and peridentitis

Category Spore- forming: rod, Gram(+)--Clostridium Nonspore- forming: see next slides