More than 150 years ago in London, an astute physician, John Snow, described the mode of transmission of cholera (nearly 30 years before Robert Koch discovered the causative agent, Vibrio cholerae; see photo and slide show), and a visionary engineer, Joseph Bazalgette, established an effective means of preventing it: the provision of municipal sanitation. Cholera is thus one of the first infections whose mode of transmission was understood and for which effective prevention measures, collectively referred to as &quot;the sanitary revolution,&quot; were developed and implemented. Because of these early observations and interventions, cholera has become vanishingly rare in the United States and other developed countries. From NEJM 0309
Transcript of "overview of systems"
Microorganisms and human
• Things to cover
– Diseases of Skin and Eyes
– Diseases of the Nervous system
– Diseases of the Cardiovascular & Lymphatic
– Diseases of the Respiratory System
– Diseases of the Digestive System
How I will tackle these
• Structure and function.
• Normal Microbiota
• Some of the diseases (More diseases to
• You will provide more of the details
Skin and Eyes
• Physical and chemical barrier against
• Moist areas have greater number of
• Epidermis contains flattened cells of keratin
and is essentially waterproof.
• Dermis is the living part, contains follicles,
ducts and glands that act as week point for
• Sebum and perspiration can inhibit growth
• Same also provide nutrients to microbiota
• The body and body cavities are lined with
• Mucous membranes secrete mucus.
• Divide rapidly, resistant to desiccation and
• Mostly gram positive cocci.
• Never completely absent.
• Propionibacterium metabolize oil
• Pityrosporum ovale are yeast that grow in
oily secretions, cause dandruff.
Staphylococcal Skin Infections
– Infections of hair follicles
– Folliculitis of an eyelash
– Abscess; pus surrounded by inflamed tissue
– Inflammation of tissue under the skin
• Candida albicans (yeast)
• Candidiasis may result from suppression of
competing bacteria by antibiotics
• Occurs in skin; mucous membranes of
genitourinary tract and mouth
• Thrush is an infection of mucous
membranes of mouth
• Topical treatment with miconazole or
• P. h. corporis
– Feed on blood
– Lay eggs (nits) on
– Treatment with
• Conjunctivitis (pinkeye)
– Haemophilus influenzae
– Various microbes
– Associated with unsanitary contact lenses
• Neonatal gonorrheal ophthalmia
– Neisseria gonorrhoeae
– Transmitted to newborn's eyes during passage
through the birth canal
– Prevented by treatment newborn's eyes with
Microbial Diseases of the Eye
• CNS is brain and spinal cord. Is encased
and protected by bone and membranes.
• PNS are nerves outside of the Central
nervous system. Is not protected as
extensively and is a rout into the CNS.
• Membranes of the CNS
– Dura mater, arachnoid and piamater
• Cerebrospinal fluid instead of blood
circulates between the arachnoid and
piamater in the subarachnoid space.
• Cerebrospinal fluid is totally separate from
the blood and circulatory system.
• Blood brain barrier
• Entry to CNS by bacteria is through
peripheral nerves, though blood and
• Meningitis is an infection of the meninges
• Encephalitis is an infection of the brain.
• Clostridium tetani
• Gram-positive, endospore-forming, obligate
• Grows in deep wounds
• Tetanospasmin released from dead cells
blocks relaxation pathway in muscles
• Prevention by vaccination with tetanus
toxoid (DTP) and booster (dT)
• Treatment with tetanus immune globulin
• Clostridium botulinum
• Gram-positive, endospore-forming, obligate
• Intoxication due to ingesting botulinal toxin
• Botulinal toxin blocks release of
neurotransmitter causing flaccid paralysis
– Proper canning
– Nitrites prevent endospore germination in
• Treatment: supportive care and antitoxin
• Infant botulism results from C. botulinum
growing in intestines
• Wound botulism results from growth of C.
botulinum in wounds.
• Caused by prions
– Sheep scrapie
– Creutzfeldt-Jakob disease
– Bovine spongiform encephalopathy
• Transmitted by ingestion or transplant or
• Chronic, fatal
Cardiovascular and Lymphatic
Systems Ch 23
• Consists of heart, blood and blood vessels
• Lymph, lymph vessels, lymph nodes and
Body Fluids and Flow
• Heart circulates substances to and from
• Blood is a mixture of plasma and cells.
• Most substances are dissolved in plasma
• RBC’s carry oxygen.
• WBC’s are involved in defense.
• Interstitial fluid is essentially plasma and
exits from capillaries
growing in the
• Severe sepsis
– Decrease in
• Septic shock
– Low blood
Sepsis and Septic Shock
• Gram-negative Sepsis
– Endotoxins caused blood pressure decrease
– Antibiotics can worsen condition by killing
• Gram-Positive Sepsis
– Nosocomial infections
• Staphylococcus aureus
• Streptococcus pyogenes
• Group B streptococcus
• Enterococcus faecium and E. faecalis
Viral Hemorrhagic Fevers
Yellow fever Flavivirus Aedes aegypti Monkeys
Dengue & DHF Flavivirus • A. aegypti
Marbug Filovirus • Monkeys
Ebola Filovirus • Monkeys
Lassa fever Arenavirus • Rodents
Arenavirus • Rodents
Bolivian Arenavirus • Rodents
• Plasmodium vivax, P. ovale, P malariae, P.
• Anopheles mosquito
Respiratory System Ch 24
• Most common type of infection
• Usually first on way to infection.
Microbial Diseases of
the Upper Respiratory
• Laryngitis: S. pneumoniae, S. pyogenes,
• Tonsillitis: S. pneumoniae, S. pyogenes,
• Sinusitis: Bacteria
• Epiglottitis: H. influenzae
• Upper respiratory: nose, pharynx, middle
ear and auditory tubes.
• Filtration by coarse hairs
• Ciliated mucous membranes of nose and
throat trap airborne particles (greater than
• Associated with lymphoid tissues (tonsils,
Lower respiratory system
• Larynx, trachea, bronchial tubes and
• Ciliary escalator prevents microbes from
reaching the lungs.
• Alveolar macrophage protect lungs.
• Respiratory mucus contains IgA
• Bacteria, viruses, & fungi cause:
Microbial Diseases of the
Lower Respiratory System
Digestive System Ch 25
• Second most common illnesses
• Usually ingestion of microbes and toxins.
• Fecal-oral transmission is broken by
proper disposal of sewage, disinfection of
drinking water and proper food prep and
• GI or alimentary canal: mouth, pharynx,
esophagus, stomach, small intestine and
large intesting, colon, anus.
• Accessory organs: teeth, tongue, salivary
glands, liver, gallbladder and pancrease.
• Charged with ingestion, digestion,
absorption and elimination.
• Lots and unknown number occupy the
• Streptococcus mutans in mouth produces
• Dextran from bacteria is plaque
• Bacteria number are reduced in stomach.
• Normal flora in lower gut.
• >300 species in mouth
• Large numbers in large intestine, including:
– E. coli
• Symptoms usually include diarrhea,
• Treated with fluid and electrolyte
• Infection caused by growth of pathogen
– Incubation from 12 hr to 2 wk
• Intoxication caused by ingestion of toxin
– Symptoms appear 1-48 hr after ingestion
Bacterial Diseases of the Lower
Urinary and Reproductive systems
• Regulates chemical components of blood
excretes nitrogenous waste.
• Infections can be from outside source or
form normal microfloura.
• Microbes can use a system to transfer
gametes to also transfer themselves.
Microbial Diseases of
the Urinary and
• Microbes usually enter the urinary
system through the urethra
• Microbes usually enter the
reproductive system through the:
– Vagina (females) or urethra (males)