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Biology 318
Normal Flora, Nosocomial Infections
Ecology Vocabulary
Symbiosis - 2 species living together
Mutualism - both species benefit
Commensal - 1 benefits, 1 no gain/loss
Parasitism - 1 benefits, 1 loses
Normal or Indigenous Flora
Infect infants within a year - 1011 bacteria
Normal or Indigenous Flora
Outcompete or kill incoming pathogens
Normal or Indigenous Flora
BUT - Antibiotics kill both good and bad!
Normal or Indigenous Flora
Educate defenses, keep alert
Skin Flora
Thick, salty, dead barrier favors Gram (+)
Hairy, moist places highly colonized - BO
Common - Staphylococcus epidermidis
Recall - 30-70% also carry S. aureus!
Transient fungi, Gram (-) from feces, soil
Respiratory Tract and Mouth
Lower - trachea, lungs - should be sterile
Respiratory Tract and Mouth
Upper – Staphylococcus, Streptococcus
Convert simple sugars to acid/cavities
GI Tract
Colon - 500+ species, most mutualistic…
Make vitamins, amino acids, aid digestion
e.g. Gram (+) Clostridium difficile
e.g. Gram (-) Escherichia
Genitourinary (GU) Tract
Kidney/bladder sterile - acid urine flushes
Urethra - skin and GI flora, clean-catch!
Genitourinary (GU) Tract
Vaginal acid-producing Lactobacillus…
But antibiotics can lead to fungi takeover
Some Flora Relevant Diseases
Infant Botulism - C. botulinum
Review Adult Botulism - same agent/toxin
Infant eats spores - honey, produce, soil...
Low GI flora - spores germinate, toxin
100 infant cases/year; 10 times adult rate!
Chronic Diarrhea/Colitis - C. difficile
Long-term antibiotics kill all GI flora…
Except C. difficile spores - germinate…
Week - GI exotoxin, potentially fatal colitis
Nosocomial
Infections
History
1840 - Semmelweis
medical handwashing
Hospital Control History
1850 Nightingale - sanitation, crowding
Hospital Control History
1870 Lister - surgical antiseptics
Nosocomial Infections - ICU Data/Year
2 million (5% patients) - 100,000 die
Added cost = $5 billion; stay = 2-4 weeks
Most pathogens = opportunistic flora!
70% pathogens drug-resistant - overuse!
Why?
Personnel don’t follow
guidelines!
More
immunocompromised
patients!
More drug-resistant
pathogens!
Nosocomial Pneumonia - 40,000/year
Lungs/alveoli - can invade blood
Patient crowding, respirators, nebulizers
Top - invasive S. aureus, MRSA
Recall - S. pneumoniae causes most
bacterial pneumonia outside hospital.
Nosocomial UTI - 30,000/year
Infection of bladder - can invade kidney
Poorly handled/washed/inserted catheters
Top - Escherichia
Same top UTI agent outside hospital more women, bad wiping/hygiene, STD.
Nosocomial Septicemia - 22,000/year
From needles, surgery, burns, wounds…
Or from invasive lung, UTI, etc. infections
Top - plastic-binder S. epidermidis, MRSE