Diseases

Chapters 21-26

Microorganisms and human Disease

• Things to cover– Diseases of Skin and Eyes– Diseases of the Nervous system– Diseases of the Cardiovascular & Lymphatic

System– 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 come)– Bacterial– Viral– Other

• You will provide more of the details

Skin and EyesCh 21

• Physical and chemical barrier against microbes

• Moist areas have greater number of bacteria

• 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 bacterial invasion.

• Sebum and perspiration can inhibit growth of microbes.

• Same also provide nutrients to microbiota

• The body and body cavities are lined with epithelia cells.

• Mucous membranes secrete mucus.

What does the integument system do?

Microbiota

• Divide rapidly, resistant to desiccation and high salt.

• Mostly gram positive cocci.

• Never completely absent.

• Propionibacterium metabolize oil

• Pityrosporum ovale are yeast that grow in oily secretions, cause dandruff.

Staphylococcal Skin Infections

• Folliculitis– Infections of hair follicles

• Sty– Folliculitis of an eyelash

• Furuncle– Abscess; pus surrounded by inflamed tissue

• Carbuncle– Inflammation of tissue under the skin

Staphylococcal Skin Infections

• Impetigo of the newborn

• Toxemia• Scalded skin

syndrome• Toxic shock

syndrome

Figure 21.4

• Streptococcus pyogenes

• Group A beta-hemolytic streptococci

• M proteins

Streptococcal Skin Infections

Figure 21.5

• Erysipelas

• Impetigo

Streptococcal Skin Infections

Figure 21.6, 7

• Streptokinases

• Hyaluronidase

• Exotoxin A, superantigen

• Cellulitis

• Necrotizing fasciitis

Invasive Group A Streptococcal Infections

Figure 21.8

• Pseudomonas aeruginosa– Gram-negative, aerobic rod– Pyocyanin produces a blue-green pus

• Pseudomonas dermatitis

• Otitis externa

• Post-burn infections

Infections by Pseudomonads

• Papillomaviruses– Treatment:

• Removal– Imiquimod (stimulate interferon production)– Interferon

Warts

• Smallpox (Variola)– Smallpox virus

(Orthopox virus)– Variola major has

20% mortality– Variola minor has

<1% mortality

• Monkeypox– Prevention by

smallpox vaccination

Poxviruses

Figure 21.9

• Measles virus• Transmitted by

respiratory route• Macular rash and Koplik's

spots• Prevented by vaccination• Encephalitis in 1 in 1000

cases• Subacute sclerosing

panencephalitis in 1 in 1,000,000 cases

Measles (Rubeola)

Figure 21.14

• Dermatomycoses: tineas or ringworm

• Metabolize keratin

• Trichophyton infects hair, skin, nails

• Epidermophyton infects skin and nails

• Microsporum infects hair and skin

• Treatment– Oral griseofulvin– Topical miconazole

Cutaneous Mycoses

Cutaneous Mycoses

Figure 21.16

• 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

nystatin

Candidiasis

Candidiasis

Figure 21.17

• Pediculus humanus capitis (head louse)

• P. h. corporis (body louse)– Feed on blood– Lay eggs (nits) on

hair– Treatment with

topical insecticides

Pediculosis

Figure 21.19

• 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

antibiotics

Microbial Diseases of the Eye

Nervous SystemCh22

• 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

More nervous

• 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 lymphatic system.

• Meningitis is an infection of the meninges

• Encephalitis is an infection of the brain.

What does the Nervous system do?

Normal Microbiota?

• Fever, headache, stiff neck

• Followed by nausea and vomiting

• May progress to convulsions and coma

• Diagnosis by Gram stain of CSF

• Treated with cephalosporins

Bacterial Meningitis

Bacterial Meningitis

Table 22.1

• Clostridium tetani

• Gram-positive, endospore-forming, obligate anaerobe

• 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

Tetanus

• Clostridium botulinum • Gram-positive, endospore-forming, obligate

anaerobe• Intoxication due to ingesting botulinal toxin • Botulinal toxin blocks release of

neurotransmitter causing flaccid paralysis• Prevention:

– Proper canning– Nitrites prevent endospore germination in

sausages

Botulism

• Treatment: supportive care and antitoxin

• Infant botulism results from C. botulinum growing in intestines

• Wound botulism results from growth of C. botulinum in wounds.

Botulism

• Caused by prions– Sheep scrapie– Creutzfeldt-Jakob disease– Kuru– Bovine spongiform encephalopathy

• Transmitted by ingestion or transplant or inherited

• Chronic, fatal

Transmissible Spongiform Encephalopathies

Transmissible Spongiform Encephalopathies

Figure 22.17a

Cardiovascular and Lymphatic Systems Ch 23

• Consists of heart, blood and blood vessels

• Lymph, lymph vessels, lymph nodes and lymphoid organs.

Body Fluids and Flow

• Heart circulates substances to and from tissue cells.

• 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

Normal Microbiota?

• Life Loads?

• Sepsis– Bacteria

growing in the blood

• Severe sepsis– Decrease in

blood pressure

• Septic shock– Low blood

pressure cannot be controlled

Sepsis and Septic Shock

Figure 23.3

• Gram-negative Sepsis– Endotoxins caused blood pressure decrease– Antibiotics can worsen condition by killing

bacteria

• Gram-Positive Sepsis– Nosocomial infections

• Staphylococcus aureus• Streptococcus pyogenes• Group B streptococcus• Enterococcus faecium and E. faecalis

Sepsis

Viral Hemorrhagic FeversClassic

Yellow fever Flavivirus Aedes aegypti Monkeys

Dengue & DHF Flavivirus • A. aegypti• A.

albopictus

No known reservoir

Emerging

Marbug Filovirus • Monkeys (?)

Ebola Filovirus • Monkeys (?)

Lassa fever Arenavirus • Rodents

Argentine hemorrhagic fever

Arenavirus • Rodents

Bolivian hemorrhagic fever

Arenavirus • Rodents

Hantavirus pulmonary syndrome

Hantavirus • Rodents

• Plasmodium vivax, P. ovale, P malariae, P. falciparum

• Anopheles mosquito

Malaria

12.31b

Respiratory System Ch 24

• Most common type of infection

• Usually first on way to infection.

Microbial Diseases of the Upper Respiratory

System

• Laryngitis: S. pneumoniae, S. pyogenes, viruses

• Tonsillitis: S. pneumoniae, S. pyogenes, viruses

• 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 10um)

• Associated with lymphoid tissues (tonsils, and adenoids)

Lower respiratory system

• Larynx, trachea, bronchial tubes and alveoli.

• Ciliary escalator prevents microbes from reaching the lungs.

• Alveolar macrophage protect lungs.

• Respiratory mucus contains IgA antibodies

• Bacteria, viruses, & fungi cause:– Bronchitis– Bronchiolitis– Pneumonia

Microbial Diseases of the Lower Respiratory System

What do the lungs do?

Normal Microbiota

• Of throat and nasal cavity can include pathogens.

• Lower respiratory system is usually sterile because of ciliary escalator.

• Aspergillus

• Rhizopus

• Mucor

Opportunistic fungi involved in respiratory disease:

Mucor rouxii

Figure 12.2b, 12.4

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 storage.

Structure Function

• 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.

Normal microbiota

• Lots and unknown number occupy the mouth.

• Streptococcus mutans in mouth produces acid.

• 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:– Bacteroides– E. coli– Enterobacter– Klebsiella– Lactobacillus– Proteus

Normal Microbiota

What does the gut do?

• Symptoms usually include diarrhea, gastroenteritis, dysentery

• Treated with fluid and electrolyte replacement

• 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 Digestive System

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

Reproductive Systems• Microbes usually enter the urinary

system through the urethra

• Microbes usually enter the reproductive system through the:– Vagina (females) or urethra (males)

Function?

• Urinary bladder and upper urinary tract sterile

• Lactobacilli predominant in the vagina

• >1,000 bacteria/ml or 100 coliforms/ml of urine indicates infection

Normal Microbiota

• Prevented by condoms

• Treated with antibiotics

Sexually Transmitted Diseases (STDs )

Websites.

• STD’s http://hab.hrsa.gov/publications/hrsawomen/colorplates/colorplates.htm