Normal flora for skin

• Staphylococci
• Micrococci
• Diphtheroids
• Gram-positive
• Salt tolerant

Two types of bacteria that frequently cause skin disease

Staphylococcus

Streptococcus

Folliculitis

Infection of hair follicles

Sty

Acne

Most common skin problem (17 million affected)

Occurs when sebum channels are blocked with shed cells

Caused by Propionibacterium acnes

Best drug to treat with - Isotretinoin (serious side fx)

Chicken Pox

Transmitted via respiratory route

Pus-filled vesicles

Virus may remain latent in dorsal root ganglia

Much more severe in adults

Caused by Herpes Varicella-zoster virus

Smallpox

Extremely serious disease - very deadly in Middle Ages

Starts as respiratory, but leads to pox lesions on skin

Caused by Variola virus

First disease artificially controlled (vaccine)

First eradicated in 1977 in Africa

Cutaneous Mycoces

Infects epidermis, hair, nails

Dermatophytes: tineas or ringworm

Metabolizes keratin

Ringworm, jock itch, athlete's foot

Topical or oral treatment

Acanthamoeba kerititis

Transmitted from water

Associated with unsanitary contact lenses

Microbes can enter the Nervous System by:

• Trauma (skull or bone fractures)
• Medical procedures (spinal tap)
• Along peripheral nerves (inner ear infection)
• Blood or lymph

Meningitis

Inflammation of meninges

Encephalitis

Inflammation of the brain

Bacterial Meningitis

• Fever, headache, stiff neck
• Followed by nausea & vomiting
• May progress to convulsions and coma
• Diagnosis by Gram-stain of CSF
• Treated with cephalosporins

Haemophilus influenzae Meningitis

• Occurs mostly in children (6 mo - 4 yr)
• Gram-neg aerobic bacteria
• Normal flora for throat
• Capsule antigen type B
• Prevented by Hib vaccine

Neisseria Meningitis

• Neisseria meningitidis
• Gram neg. aerobic cocci, capsule
• 10% are carriers of nasopharyngeal
• Begins as throat infection and rash
• Caused by endotoxins
• Antibiotics for treatment

Streptococcus pneumoniae Meningitis

• Gram-posi diplococci
• 70% are carriers of nasopharyngeal
• Most common in children (1 mo - 4 yr)
• Mortality: 30% children, 80% elderly
• Some antibiotic resistance

Listeriosis

• Listeria monocytogenes
• Gram-neg aerobic rod
• Usually food borne (dairy products)
• Can be transmitted to fetus
• Reproduce in phagocytes
• Shed in feces

Tetanus

• Clostridium tetani
• Gram-posi, endospore-forming, obligate anaerobe
• Grows in deep wounds
• Tetanospasmin released from dead cells blocks relaxation pathway in muscles
• Spastic paralysis, lockjaw
• Prevented by DTP vaccine and dT (10 years)

Botulism

• Clostridium botulinum
• Gram-posi, endospore-forming, obligate anaerobe
• Intoxication due to ingesting botulinal toxin
• Botulinal toxin blocks release of neurotransmitter causing flaccid paralysis
• Very heat resistant
• Nitrites kill, but are very carcinogenic
• Treatment: supportive care and antitoxin

Leprosy

• Mycobacterium leprae
• Acid-fast rod that grows best at 30 deg celsius
• Grows in peripheral nerves & skin cells
• Transmission requires prolonged contact w/ infected person

Leprosy

• Tuberculoid (neural) form: loss of sensation in skin areas & positive lepromin test
• Lepromatous (progressive) form: Disfiguring nodules over body, negative lepromin test (hands and nose)
• Treatment: combination of sulfur drugs

Cryptococcus neoformans Meningitis

• Soil fungus assoc. w/ pigeon & chicken dropping
• Transmitted by respiratory route
• Spreads through blood to CNS
• Mostly occurs in immunosuppressed
• Treatment: amphotericin B & flucytosine

African Trypanosomiasis

• Protozoan
• Trypanosoma brucei gambiense is chronic (2 to 4 yr)
• T.b. rhodesiense is more acute (few mo)
• From blood to CNS
• Dullness of mental ability, coma, death
• Transmitted from animals to humans by tsetse fly
• Prevention: elimination of the vector
• Eflornithine blocks an enzyme necessary for the parasite
• Parasite evades Ab through Ag variation

Prions

• Self-replicating proteins with no detectable nucleic acid
• Long incubation periods
• Disease of the CNS that progresses slowly and causes spongiform degeneration

Sepsis & Septic Shock

• Sepsis (septicemia): bacteria growing in blood
• Severe sepsis: decrease in BP and dysfunction of at least one organ
• Septic shock: Often occurs with septicemia (inflammation of lymph vessels and nodes)
• Red streaks under skin

Sepsis

• Gram-neg sepsis
• E. coli, pseudomonas, enterobacter
• Endotoxins cause BP decrease
• Antibiotics can worsen condition by killing bacteria
• Many are nosocomial (IV, catheter)

Sepsis

• Gram-posi sepsis
• Nosocomial
• Staphylococcus areus
• Streptococcus pyogenes
• Group B streptococcus
• Enterococcus faecium and E.faecalis

Endocarditis

Inflammation of the endocardium (inner layer)

Rheumatic Fever

• Autoimmune complication of Streptococcus progenies infections
• Starts as strep throat
• Arthritis and fever
• Can cause endocarditis
• Usually 4-18 yr

Tularemia

• Francisella tularensis, gram-neg rod
• Transmitted from rabbits and deer by deer flies
• Usually through skin breaks, aerosol or eat
• Bacteria reproduce in phagocytes

Brucellosis (Undulant fever)

• Brucella, gram-neg rods that grow in phagocytes
• B. abortus most common (elk, bison, cows)
• Undulating fever that spider to 40 deg celsius each evening
• Transmitted vial milk from infected animals/contact

Anthrax

• Bacillus anthracis, gram-posi, endospore-forming aerobic rod
• Found in soil
• Cattle routinely vaccinated
• Treated w/ ciprofloxacin or doxycycline
• Death due to exotoxins

Cutaneous Anthrax

• Endospores enter through minor cut
• 20% mortality

GI Anthrax

• Ingestion of undercooked/contaminated food
• 50% mortality

Inhalational Anthrax

• Inhalation of endospores
• 100% mortality

Gangrene

• Ischemia
• Loss of blood supply to tissue (anaerobic)
• Necrosis (death of tissue)
• Death of soft tissue

Gas Gangrene

• Clostridium perfringens, gram-posi, endospore-forming anaerobic rod
• Grows in necrotic tissue
• Treatment: surgical removal of dead tissue and/or hyperbaric chamber

Lyme Disease

• Organism - also Borrelia
• Vector: tick
• Reservoir: mice
• Ticks feed on mice & then deer or human
• Stages: rash, flu-like symptoms, heart problems, nervous signs may appear

Typhus

• Rickettsia, obligate intracellular parasite
• Causes several diseases
• Vector: arthropod
• Infects: endothelial cells of BV
• Rocky Mtn. Spotted Fever
• Rash, fever, headache, later kidney & heart failure

Infectious Mononucleosis

• Epstein-Barr virus (HV4)
• Acquired during childhood
• Transmitted via saliva
• Fever, sore throat, swollen lymph nodes
• Immune to re-infection
• Remains latent, always a carrier

Burkitt's Lymphoma

• Cancerous tumors of jaw
• EBV
• Cancer in immunosuppressed individuals, malaria and AIDS patients
• Mostly Africa
• Nasopharyngeal carcinoma
• Major cause of death in Asia

Cytomegalic Inclusion Disease

• Cytomegalovirus (HV5)
• Infected cells swell
• Latent in WBC
• May be asymptomatic or mild
• Transmitted across placenta, can cause mental retardation
• Sexually, blood, transplant can also transmit
• AIDS patients at risk

Dengue Fever

• Vector: mosquito
• Also called breakbone fever: severe muscle and joint pain
• Similar to Yellow Fever but milder
• Endemic in Caribbean

Dengue Hemorrhagic Fever

• Induces shock and fever
• Die few hours after infection
• Southeast Asia

Toxoplasmosis

• Toxoplasma gondii
• Reservoir: cats
• Pass oocysts in feces to water or food
• Uncooked meat, cat feces
• Congenital damage to unborn fetus via placenta

Malaria

• Plasmodium
• Transmission: mosquito
• Enters from mosquito saliva to blood stream and infects and reproduces in the blood cells, all burst open at once - severe fever
• Treatment: quinine
• No vaccine

Otitis Media

• Common Cold
• Rhinovirus
• We tend to build up immunity to colds, as we get older we get fewer colds

Pertussis

• Bordetella pertussis
• Violent cough, gasping for air in between coughs, fever
• Recovery can last for months
• Severe in children >1 yr
• Treated with Erythromycin

Bacterial pneumonias

• Inflammation of lungs
• Most pneumonias are bacterial in origin

Pneumonococcal pneumonia

• Streptococcus pneumoniae
• Gram-posi encapsulated diplococci
• High fever, breathing difficulty, chest pain
• Usually affects people w/ weakened immunity
• Treated with penicillin

Mycoplasmal Pneumonia

• Mycoplasmal pneumoniae
• Pleomorphic, wall-less bacteria
• Mild symptoms
• Very hard to culture
• Treated with tetracycline

Legionellosis

• Legionella pneumophila
• High fever, cough, general symptoms of pneumonia
• Transmitted by water and AC
• Treated with Erythromycin

Psittacosis (Ornithosis)

• Chlamydia psittaci
• Gram-neg, intracellular bacterium
• Transmitted by elementary bodies from bird droppings to humans
• Parakeets and parrots
• Fever, headache, chills, delirium
• Treated with tetracycline

Respiratory Syncytial Virus (RSV)

• Common in infants
• Causes cell fusion (syncytium) in cell culture
• Symptoms: coughing
• Diagnosis by serologic test for virus and Ab
• Treated by Ribavirin

Influenza

• Influenzavirus
• Contains 8 separate RNA segments
• Chills, fever, headache, general muscular aches
• No GI symptoms

Influenza

• Hemagglutinin (H) spikes used for attachment to host cells
• Neuraminidase (N) spikes used to release virus from cell
• Antigenic shift changes H and N spikes
• Due to genetic recombination between diff. strains infecting same cells
• Allows virus to avoid IgA Ab

Coccidioidomycosis

• Coccidioides immitis
• Transmitted by airborne arthrospores
• Chest pain, fever, coughing, weight loss
• Strong resemblance to TB
• Treated by Amphotericin B

Coccidioidomycosis

• Pneuomocystis Pneumonia
• Pneumocystis jiroveci (P.carinii) found in healthy human lungs
• Occurs in newly infected infants and immunosuppressed

Dental Caries

• Streptococcus mutants: worst organism to break down enamel
• Bacteria convert sucrose into lactic acid and erodes tooth enamel

Saliva functions

• Breakdown CHO
• Neutralizes acids
• Washes away bacteria
• Lubrication

Gingivitis

• Periodontal disease in the gums
• Symptoms: bleeding gums after brushing

Staphylococcal food poisoning

• Staphylococcus aureus
• Leading cause of gastroenteritis
• Can tolerate high osmotic pressure
• Enterotoxins are superantigens
• Toxin is durable and can stand reheating once formed
• Vomiting, cramps, diarrhea
• Recover in 24 hours

Salmonellosis

• Salmonella enterica- various strains
• Second most common food poisoning
• Mortality (<1%) due to septic shock caused by endotoxin
• High risk foods: meat products, poultry, eggs
• Also infection from reptiles
• Incubation: 12-36 hours
• Abdominal pain and diarrhea
• Cook food thoroughly to prevent

Escherichia coli Gastroenteritis

• Escherichia coli
• Occurs as traveler's diarrhea and epidemic diarrhea in nurseries
• Diarrhea is symptom
• Enterohorrhagic strains such as E. coli O157 produce Shiga toxin
• Treatment: Oral rehydration and self-limits

Hepatitis B

• Hepatitis B Virus (HBV)
• Transmitted by transfusion, IV drug use, sex
• Incubates for 3 mo
• Symptoms vary, may be mild - loss of appetite, low fever, joint pain
• Fever, nausea, jaundice

Hepatitis B

• Most people recover
• Complications: chronic carrier (10%) and liver cancer
• Treated by vaccine

Hepatits C

• Hepatits C Virus (HCV)
• IV drug use most common way to transmit
• Mild symptoms, 85% of patients develop chronic hepatitis
• May lead to cirrhosis of liver/ liver cancer
• Treated with interferons

Hepatitis D

• Hepatitis D Virus (HDV)
• Person has to be infected with HBV
• Chronic HBV w/ HDV - superinfection
• Increases mortality rate

Hepatits E

• Hepatitis E Virus (HEV)
• Transmitted by fecal-oral route
• Resembles HAV
• No chronic cases
• Treated by self-limiting

Norovirus

• 50% of US Adults have Ab
• 1-2 day incubation, 1-3 day illness
• Treated with rehydration

Tapeworms

• Taenia spp.
• Life cycle w/ three stages
• Egg: excreted in feces and ingested by animal
• Cysticerci: in muscle of animal
• Adult tapeworm

Tapeworms

• Transmitted as cysticerci in undercooked food
• Diagnosed by observing proglottids and eggs in feces
• Treated with praziquantel
• Cysticerci may develop in humans
• Neruocysticercosis may require surgery

Ascariasis

• Ascaris lumbricoides
• Lives in human intestines
• Transmitted by ingesting Ascaris eggs

Cystitis

• Inflammation of urinary bladder
• Common in females
• Usually caused by E.coli or S. saprophyticus
• Painful urination and leukocytes in urine
• Treated with Ampicillin

Gonorrhea

• Neisseria gonorrhoeae
• Attaches to oral pharyngeal area, eyes, rectum, urethra, opening of cervix, external genitals by fimbrae
• Females may be asymptomatic, males have painful urination and pus discharge
• Treatment with Ab
• Untreated may result in endocarditis, meningitis, arthritis
• Can be transmitted to newborn's eyes

Nongonococcal Urethritis

• Chlamydia trachomatis
• May be transmitted to newborn's eyes
• Painful urination and watery discharge
• Symptoms are mild & patients don't know they have it
• Males: inflammation of epididymis
• Females: inflammation of uterine tubes
• Treated with tetracycline

Syphilis

• Treponema pallidum (spirochete)
• Transmitted by direct contact and can invade intact mucous membranes or penetrate through breaks in skin
• Primary stage: chancre at site of infection
• Secondary: skin and mucosal rashes
• Laten period: no symptoms
• Tertiary: gummas on many organs
• Congenital: neurological damage
• Primary & secondary stages treated with penicillin

Genital Herpes

• Herpes simplex virus 2
• Lesions appear after incubation period of one week
• Urination can be painful, walking is uncomfortable, even clothing is uncomfortable
• Recurrences from virus latent in nerves
• Triggered by stress, illness or scratching area
• Suppressed by acyclovir or valacyclovir

AIDS

• Usually sexually transmitted
• Attacks immune system
• Lesions from other infections increase spread
• No cure