Normal flora as a source of opportunistic pathogens

(S. epidermidis, S. mutans, P. aeruginosa, Candida albicans)

What is a pathogen? Stanley Falkow, 1997. ASM News 63: 359-365.

“A primary pathogen long-term survival absolutely depends upon its ability to replicate and to be transmitted in a particular host whereas an opportunistic pathogen does not.” S. Falkow

 

ii.       ???

Biofilms as reservoirs for disease.

See Flanders and Yildiz Chap 17 In Microbial Biofilms by Ghannoum and O’Toole

“From the medical point of standpoint, the rate of microbial replication reflects, and often defines, the incubation period of a disease. However, it also defines the stealth phase during which the microorganism avoids destruction by host defenses and, instead attains sufficient numbers to carry its progeny forward.”  S. Falkow, ASM News 63.
“The key distinction then is that a pathogen has the inherent capacity to breach host cell barriers, whereas a commensal species and opportunistic pathogens do not.” S. Falkow  “Commensals may cause opportunistic infections when they are introduced into such privileged host sites or if some other ordinarily insurmountable host defense is breached.” S. Falkow ASM News 63.

 

An example: Human Oral Microbes and Dental caries

            a. Mechanism of pathogenicity
            b. Microbial succession
            c. Coaggregation Paul Kolenbrander
            d. Keystone species – Fusobacterium nucleatum
            e. Prevention