Rickettsia & Chlamydia

"Obligate Intracellular Parasites"

Have Cell Wall, DNA & RNA, but lack many enzymes

Invade/Live in Host

Rickettsias - Gram - Rod/Cocci

Chlamydia - Gram - Cocci

Mycoplasma

Pleomorphic m.o.

Have DNA, RNA & Enzymes but lack Cell Wall

"Fried Egg" Colony Appearence

Mycobacteria

"Acid-Fast" m.o.

Do not Gram Stain due to High Lipid Content in Cell Wall

Waxy Coating is resistant to water, chemicals, and RX

Staphylococcus aureus

Folliculitis/Impetigo/SSSS/TSS

Gram + Coccus

NF (oportunistic) that lives on Salt

Produces Coagulase, Leukocidin, Toxins, and Hemolysis

Folliculitis - inf of hair follicle

impetigo - crusty surface vesicles (newborns)

SSSS - deeper infections of impetigo (exotoxin release)

TSS - SQ Infection with exotoxin release (rash/shock (low BP)/Fever/Vomiting)

Streptococcus pyogenes

Impetigo w/ Pyoderma

Gram + Coccus (Aerotolerant)

Beta-Hemolysis, Group A most common

Impetigo - Crusty Surgace Vesicles with Pyoderma (Pus)

Erysipelas - deeper, wound Inf (necotizing fascitis "Flesh-Eating")

Herpes Simplex Virus (HSV-6)

Roseola

Varicella/Herpes-Zoster

Chicken Pox / Reye's Syndrome

Chicken Pox - Upper RTI -> Vesicles appear on skin -> latent Virus in Spinal Cord -> Shingles

Varivax Vaccine

Reye's Syndrome - Severe Complication associated with Viral Inf - Aspirin Increases Risk

Morbillivirus

Measles (Rubeola)

Measles (Rubeola) -> Upper RTI -> Koplik spots in OC  -> Spotty macular Rash -> Brain -> Slow Inf

Leads to SSPE (Subacute Sclerosing Panencephalitis)

Togavirus

German Measles (Rubella)

German Measles (Rubella) - Begins as Mild Upper RTI in Children -> Fain Macular Rash

TORCH - Assay Screens for Rubella Antibody Titer in Women during Pregnancy

Parvovirus B19

Erythema Infectiousum (5th Disease)

Erythema Infectiosum (5th Disease)

starts as Mild Flu-Like S/s -> Lacy Rash on Face

-- Slapped Cheek Discase

Trichophyton sp.

Tinea (Ringworm)

Cutaneous; m.o. grows on the keratin of hair, nails, skin surfaces = tinea (Ringworm)

tinea capitis - scalp

tinea barbae - beared area

tinea cruris - groin - Jock Itch

tinea unguium - nails

tinea pedis - athlete's foot

tinea corporis - body trunk

Subcutaneous; m.o. enters through skin wound

Harder to treat - medications are toxic to human cells as well as fungal infection

NF (Opportunistic) in Mucous Membranes of Throat

Oral Thrush - Inflammation of OC -> Systemic Disease

Pediculus humanus (capitis)

Pediculosis - Head Lice

Pediculosis - Head lice

m.o. feeds on blood -> itching -> secondary bacterial inf

Haemophilus influenzae Type B

Childhood Meningitis

Gram - Coccobacillus w/ Capsule

Childhood Meningitis - Upper RTI -> bacteremia -> Capillary Dmg -> Invasion of the Meninges

Neisseria Meningitidis

Miningococcal Meningitis

Gram - Diplococcus w/ Capsule

Meningococcal Meningitis - Upper RTI -> bacteremia & toxemia -> rash & invasion of meninges

Droplet Transmission - Epidemic

High Fever - Convulsions - Death

Streptococcus Pneumoniae

Pneumococcal Meningitis

Gram + Coccus w/Capsule

Pneumococcal Meningitis - Upper RTI -> Bacteremia -> Invasion of the Meninges

Most common Adult Meningitis

Otitis Media in Children

Strep are Antibiotic Resistant

Listeria Monocytogenes

Listeriosis / Meningitis

Gram + Rod

Listeriosis - NF for Animals -> Feces -> Contaminate Food and Water -> Human Ingestion

Mild GI Inf -> can produce Hemolysin to spread through out body

meningitis - invasion of CNS - Immunocompromised Host

Placental route - CNS dmg - Death

Clostridium Tetani

Tetanus (lockjaw)

Gram + Anerobic/Spogeforming Rod

"Closet Lover" = No Oxygen

tetanus (lockjaw) - deep puncture wound -> neurotoxic exotoxin -x-> muscle relaxation -> Severe muslce spasms

Clostridium botulinum

Foodborne Botulism / Infant Botulism

Gram + Anaerobic/Spongeforming Rod

Foodborne Botulism - contaminated food -> nerutoxic exotoxin -x-> blocks acetylcholine action on muscle -> flaccid paralysis

Infant Botulism - infant gut not acidic enough, no NF -> Toxin forms -> "Floppy baby Syndrome"

Mycobacterium leprae

Hansen's Disease (Leprosy)

Acid-Fast Rod

Hansen's Disease (leprosy) -> spread through secretions of infected clients -> skin and nerve inf -> causes:

tuberculod (neural) form - skin loses pigmentation & sensation

lepromatous (Progressive) form - large nodules develop with gradual loss of bone tissue

Poliomyelitis - Fecal/Saliva -> Viremia -> CNS -> Kills Nerve Cells -> Paralysis that can reoccur later in life

(post-polio syndrome)

Lyssavirus

Rabies

Rabies - bite/saliva of animal -> PNS -> CNS -> Fatal Encephalitis

s/s = hydrophobia - fear of water from throat paralysis

aerophobia - fear of air from neuralgia

Presence of Negri bodies in brain Tissue

Arbovirus (arthropod borne virus)

Encephalitis

Prion-Associated Disease

Transmissible spongiform encephalopathies

Transmissible spongiform encephalopathies - infectious proteinaceious particles enter host via ingestion or transplantation of contaminated tissue -> spongy dengeration of brain tissue

sheep scrapie & bovine spongiform encephalopathy (BSE)

Kuru - Cannibalism

Creutzfeldt-Jakob Disease (CNS Transplants)

Trypanosoma brucei

Sleeping Sickness (Coma)

Sleeping Sickness (Coma) - fly bites human -> bloodstream inf -> CNS -> Neurological dmg -> Death

m.o. can have 100(+) different Ag markers in lifetime

Naegleria fowleri

Primary Amebic Meningoencephalitis (PAM)

Escherichia coli, Serratia marcescens, Proteus species, Pseudomoonas aeruginosa, Enterobacter aerogenes

Sepsis / SIRS

Gram - Rods

Opportunistic NF on Body and mucous membranes

Enter via Wound or Iatrogenic Procedures

Sepsis - Systemic Inflammatory Response Syndrom (SIRS) -> chills & fever, septic shock -> Low BP, High HR/Resp Rate -> Multiorgan Failure -> Death

Streptococcus pyogenes

Puerperal (Childbirth) Fever / Rheumatic Fever

Gram + Coccus

Puerperal (Childbirth) Fever - Inf in uterus -> Peritonitis -> Septicemia

Rheumatic Fever - Inf of Throat -> Pharyngitis -> Joint Temporary Arthritis -> Inflammation of the Heart valves -> Heart Murmurs (MVP)

MVP is caused by auto-immune response due to Cross reactive markers of Strep Ag

Streptococcus pyogenes

 Bacterial Endocarditis

Gram + Coccus

Bacterial Endocarditis - dental/body pericing -> Inf in Blood -> subacute inflammation of heart lining & valves -> Chronic Heart Dmg -> MI

Francisella tularensis

tularemia (hunter's fever)

Gram - Rod

tularemia (hunter's fever) - inf animal / tick bite -> lives in macrophages -> septicemia -> invasion of lungs -> Pneumonia

ID50: 10 m.o. via skin wound / 50 m.o. via inhalation

Resevoir = Rabbit

Brucella abortus

Brucellosis (Bang's Disease)

Gram - Rod

Brucellosis - Ingestion from contaminated meat/unpasturized milk -> fever

Bacillus anthracis

Anthrax (Woolsorter's Disease)

Gram + Aerobic, Spongeforming Rod w/ Capsule

Anthrax - spore encounter via inhalation or ingestion of contaminated meat or unpasteurized milk -> produce toxins -> septicemia and Respiratory Failure

Clostridium perfringens

Gas Gangrene

Gram + Anaerobic Sporeforming Rod

Gas Gangrene - wound -> ichemia at site -> toxins -> soft tissue destruction (necrosis) -> gangrene -> ferments decayed tissue - gas (crepitus)

Tx: Debridment and Amputation

Hyperbaric Chamber - High O2

Frequent complication in DM pt with Decreased Peripheral Circulation

Yersinia pestis

Bubonic plague (Black Death)

Gram - Rod

Bubonic Plague - rats/squirrels -> flea bits animal then human -> "Buboes" (blackened, lymph swelling) & Fever -> Lung (pneumonic plague) -> very contagious & usually fatal within 72 hours

Borrelia burgdorferi

Lyme Disease

Gram - Spirochete

Lyme Disease - deer/mice -> deer tick -> "Bull's Eye Rash" and flu-like symptoms -> cardiac, arthritic & neurological sequelae

Ehrlichia chaffeensis

Human ehrlichiosis

atypical m.o. (Rickettsia)

deer tick -> detroys WBCs -> fever & flu-like s/s -> leukocytopenia -> Death

coinfects with Lyme Disease

Rickettsia rickettsii

Rocky Mountain Spotted Fever (typhus)

atypical m.o. (Rickettsia)

rodents, rabbits -> tick -> blood -> fever & blood vessel dmg -> rash (petechiae) - hemorrhage

Bartonella henselae

Cat-Scratch Fever

Gram - Rod

Cat-Scratch Fever - flea -> cat / cat paws (flea feces) -> cat scratch -> lymph swelling, malaise & fever

Linked to Chronic Fatique Syndrome

Epstein-Barr (EBV)

Human Herpesvirus 4

Infectious Mono - salivary glands -> mild/asymptomatic inf -> B-cell infec -> autoimmune attack - virus remains in lymph system

Downey Cells -> Swollen lymph nodes, spleen, and liver

If immunocompromised -> burkitt's lymphoma = common in childhood cancer in Africa

Cytomegalovirus

Human Herpesvirus 5

CMV inclusion Disease - Saliva -> mild "mono-like" s/s -> lies dormant in bone marrow, kidney, t-cells, and macrophages

high-risk for immunocompromised -> retinitis or fatal pneumonia

pregnant, nonimmune females -> cerebral palsy in infant

Flavivirus

Dengue (breakbone fever) / Yellow Fever

Dengue -> Mosquito -> rash, fever & extreme bone/join pain due to increased amounts of innterferon produced

Yellow Fever - Monkeys -> mosquito -> Fever/Nausea -> Spleen, heart, kidney & liver dmg -> Jaundice -> Death

Filovirus

Ebola Virus - Hemorrhagic Fever

Hemorrhagic Fever - Fruit bat -> "flu-like s/s -> Liver, spleen & lung necrosis -> hemorrhage -> shock -> death

spread via contact with contaminated blood / body fluids of humans or by fruit bat bite

Toxoplasma gondii

Toxoplasmosis

birds, rodents -> ingested domestic cats -> eggs shed in cat feces -> mild subclinical infection

can cause fatal CNS infections in immunocompromised patients

placental transfer -> miscarriage or severe fetal CNS dmg

Plasmodium species

Malaria

Malaria - Mosquito -> infects liver within 30 mins after bite -> high fever, HA, Nausea -> Destruction of RBC

4 distinct phase of life-cycle makes difficult to develop vaccine

Leishmania species

Leishmaniasis (kala azar)

Schistosoma species

Swimmer's itch / schistosomiasis

swimmer's itch - contaminated water -> skin -> rash

schistosomiasis - contaminated water -> skin -> dmg vessels -> liver, bladder, lungs or brain