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13: Microbe-Human Interactions

What are our relationships with microbes?

Symbiosis

mutualism

commensalism

parasitism

opportunism

Or?

resident microbiota vs. transient

microbial interaction antagonism/competition

cooperation

synergism

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Exposure

contamination

infection

(parenteral)

Portals of entry infant

Adhesion factors

capsules, fimbriae, spikes, hooks, suckers

adhesins

Portals of exit

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Disease terminology disease/morbidity

mortality

pathology

etiology

pathogenesis

pathogen

frank

opportunist

compromised host

Evidence for disease

symptoms

signs

syndrome

Hypersensitive, autoimmune

/psychogenic

“doctor-caused”

Koch’s Postulates (can’t always do these)

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Virulence factors: extracellular enzymes (exoenzymes) antiphagocytosis factors

collagenase & hyaluronidase capsules, M proteins

coagulase (countered by kinase)

toxins others

exotoxins (usu. fr. G+) mycobacterial waxes

endotoxin (lipid A fr. G-) leukocidins

Stages of an infectious disease

zoonosis

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Scope of a disease

Severity/duration

subclinical

(new cases)/(people at risk) (all cases)/(people at risk)

Epidemiology: occurrence

frequency & geography

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John Snow’s (1854) study of a cholera epidemic

World Health Organization (WHO)

Centers for Disease Control & Prevention (CDC), part of NIH

California Dept. of Public Health (CDPH)

Nosocomial infections At least 1 in 20 patients

iatrogenic infection

superinfection

Asepsis!!!

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CHICAGO, August 27, 2001 - ������Two women who both had c-sections at a suburban hospital contracted the so-called 'flesh-eating' bacteria.���Hospital officials said the bacteria was spread to the women from a surgical team during the procedure.������Doctors at Evanston hospital confirmed that the women were in fact infected by a member of their own surgical team.������They said there was really no way of preventing the infection because it apparently happened after one of the members of the surgical team passed gas.������On August 1st, a day after the women gave birth at Evanston hospital, they started showing signs that they were infected with a flesh-eating bacteria called Nescrotizing Fasciitis.������“I can't get into specifics too much. It was an individual who was in the operating room at the time of the c-sections,” said the director of infection control, Dr. Thomas Vescio.������At a news conference Monday, Dr. Vescio confirmed both women received c-sections in the same operating room by the same surgical team. Rectal cultures indicated the infected carrier is one member of the surgical team who tested positive for Strep A colonizing in the gut. Doctors said the infected carrier was gowned, masked and had gloves on and it's likely the bacteria became airborne. http://www.asylumnation.com/asylum/_r/showthread/threadid_14944/index.html Chicago’s Channel 5 News team: Two women undergoing C-section births at Evanston Hospital on July 31 received the necrotizing fasciitis bacteria from an OR surgeon when he cut the cheese.