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The toxin penetrates intestinal mucosa and attaches to microvilli of gut epithelial cells.
It has an enterotoxin with two subunits: A & B. Subunit B has 5 peptides that attach to the cell and Subunit A goes into the cell to cause an increase in cAMP concentration as well as adenylate cyclase activity which causes an imbalance of electrolytes which causes diarrhea.
Toxin is made of 3 proteins: PA (protective antigen), EF (edema factor) and LF (lethal factor).
PA binds to cell receptors and mediates entry of EF and LF into the cell.
EF+PA --> edema toxin
LF+PA -->lethal toxin (virulence factor)
Specimen smeared, crystal violet stain covers slide, washed, covered with iodine, washed, decolorized with alcohol (if stays purple, gram +), washed, cover with safarin stain (if stays red, gram -)
Some have flagella but not all do
Facultative Anaerobes (w or w/out oxygen)
Most cause UTI's and blood infections
Transmitted by fecal-oral route from water/food
Non-motile; no flagella but have actin-tails to zoom through cells.
Invade mucosal epithelial cells.
Cause abcesses and lesions.
Escape from phagocytosis.
Experimental vaccines stimulate IgA production
Cause dysentery-dehydration, acidosis, death
Biofilms form slimy coats on hard surfaces.
Human infections are persistent and difficult to treat.
S. epidermidis, S. aureus, P. dendruginosa
-Lipopolysaccharides - O antigen
-Flagella - H antigen
-Capsular Polysaccharides - K antigen
-Conjugative Pilus - F antigen
(transfer of plasmids)
Associated with 'food poisoning' outbreaks from chicken, peanut butter and tomatoes.
Symptoms: headache, nausea, vomiting, diarrhea, low fever
Infection provides some immunity by making subsequent infections milder.
Causes typhoid fever
Symptoms: early-constipation, later-bloody diarrhea
Pathogenesis: travel from sm intestine to lymphatics and can enter bloodstream and cause blood infections and shock
Asymptomatic carriers continue to shed bacteria in feces and may carry for life, infecting many people
Vaccines: given to travelers to endemic countries: either oral (live-attenuated) or subunit based on K-antigen
1st asymptomatic carrier of S. typhi that worked in households and infected 50 people.
She went to prison but changed her name and kept cooking and infected more households.
Ended up quarantined in hospital for life,
Bacteria that live within the gut without complication because they can survive at low numbers and don't secrete toxins or express virulence factors.
Risk factors of gaining access to new tissues: surgery, transplants, burn wounds, antibiotic treatments+long hospital stays.
Major problem because many are resistant to antibiotics
Can cause UTI's, pneumonias, bacteremia
MDR: multidrug resistance
(2+ drugs that were one effective)
XDR: Extensively-drug resistant
(resistant to nearly all drugs used to be effective)
Encourage use of:
Reduce mortality, hospital stays and acquisition of nosocomial pathogens
Most common bacteria in surface waters that form biofilm on codepods and crustaceans.
Can be identified by color of colonies.
Yellow, Comma shaped, salt-loving
200+ antigen types
Transmitted through contaminated water or fecal-oral in places with poor sewage and water treatment facilities.
Endotoxin: A-B type that acts on host intestinal epithelium (B binds host receptor, A for enzymatic activity)
Toxigenic strains El Tor and 0139 responsible for major outbreaks in humans.
Ingestion of contaminated seafood.
Symptoms: nausea, vomiting, cramps, water or bloody diarrhea
Gram (-), spiral shaped
Transmitted between people through saliva.
Survives and multiplies on epithelial side of mucous lining of stomach.
Produces urease that breaks down into ammonia and buffers mucus lining which can be tested in diagnostic assays.
Associated with gastric lymphomas and adenocarcinomas due to lifetime persistence of bacteria.
Early antimicrobial treatment prevents long-term infection.
Causes lesions, cellulitis or necrosis within hours of infection.
Gains access to abrasions or injured body sites from contaminated salt water.
Bacteremia prevented with tetracycline treatment.
More likely to affect immunocompromised
S-shaped, single flagella
From ingestion of contaminated poultry.
Symptoms: profuse, bloody diarrhea, headaches, fever, malaise
Long-term symptoms: guillian-barre syndrome, reactive arthritis, reiter's syndrome
Drug resistance: efflux pumps decrease expression of OprD porin
Invasion: Elastases, proteases, hemolysins allow bacteria to access deeper tissues
Exotoxin A: causes tissue necrosis
Type VI secretion systems: can inject toxic proteins into other bacteria to outcompete them for nutrients
Autosomal recessive mutation in CFTR gene that is defective in Na+ and Cl- transport which leads to a mucus buildup in airways.
Highly susceptible to bacterial infections such as P. aeruginosa, S. aureus and Bulkhoderia species.
70% of CF paients have P. aeruginosa infections which form biofilms that are resistant to antibiotic treatments.
Causes respiratory infections
Found in soil and water
Mostly infects immunocompromised.
Treated with carbapenems or sulfomethalzole-trimethoprim
High mortality rate without treatment.
Detection: gram-negative rods (bacilli) that can form wrinkled colonies.
Complex of several B. species from environment that can lead to bacteremia.
Can be transmitted among CF patients and lead to rapid death.
Require growth factors in blood (factors X and V)
6 serotypes based on K-antigen
Causes meningitis in children
Major cause of bacterial otitis media and sinusitis
Indicated in upper resp. tract by swollen red epiglottis
Vaccine: Type B given to infants and high-risk adults
Treated with surgical drainage and rifampin.
Transmitted by ingestion of raw pork, unpasteurized milk, untreated water and by ingesting fried pig intestines
Symptoms: abdominal pain, fever
Caused Bubonic Plague
Spread by flea/rodent bites.
Symptoms: fever, headache, chills, weakness, and swollen/tender lymph nodes, 'buboes'
50% mortality rate without treatment
Early treatment with Aminogycosides: Streptomycin or Gentamicin
Detected by serologic testing, gram-bacilli in bubos tissue.
Plasminogen-activated Protease (PAP): acts as coagulose
Endotoxin: LPS is highly toxic
Spread to blood and tissues
hemorrhaging occurs with chills, weakness, skin and other tissues turn black and die
Inhaling infected droplets and spreads from person to person.
Causes rapid pneumonia with shortness of breath, chest pain, cough, bloody mucous.
Most serious and leads to shock/death.
Gram (-), facultative aerobe
Causes whooping cough.
Binds to epithelial surface of trachea and bronchi that interferes with ciliary action.
Initial symptoms: runny nose, mild cough, apnea in infants
After 1-2 weeks: severe cough that can last 10 week.
Vaccine: DTap (kids >7) and TDaP (given to older children/adults) have diphtheria and tetanus toxoids
Treatment: Aminoglycoside antibiotics: erythromycin, azithromycin, clarithromycin
Gram (-) but do not stain gram - because peptidoglycan is in perplasm.
Transmitted in mammals from Ixodes scapularis tick bite that regurgitates bacteria in saliva.
Causes bulls-eye rash after transmission.
Can disseminate from blood to CNS (leads to facial palsy and meningitis), to Joints (leads to swelling and arthritis) and Heart (palpations and dizziness)
No treatment leads to chronic arthritis and neurological damage.
Tick-borne Relapsing Fever
Transmitted by Ornithodoros hermsii tick in western US from ticks that live in rats nests.
Antigenic variation of surface protein relapses of fever, bacteremia 3-4 times before clearance.
Treatment: Tetracycline or Erythromycin treatment for 10 days with inflammatory reactions due to the release of microbial products (high fever, rigors and hypotension)
Transmitten by louse
Problem during WW1 with 13 million cases and 5 million deaths. Mortality rate 30-70%
Obligate intracellular bacteria.
Do not survive in environment
Treatment: Tetracyclines, chloramphernicols
(Usually does not kill all bacteria so immune system must clear infection)
Never treat with Sulfonamides because incease Rickettsial growth and cause more serious disease.
Arthropod vector depends on Rickettsial species; tick, lice or fleas
Infection caused by wood ticks and dog ticks.
First days of infection: fever, headache, abdominal pain, vomiting and muscle pain.
After, Rocky Mountain Spotted Fever develops on extremities.
Immediate treatment needed to prevent serious infections
Transmitted by lice by scratching louse feces into skin that gives it access to blood vessels
Systemic disease that can be latent in lymph
Obligate intracellular pathogen that can only multiply inside of eukaryotic cells in reticulate form or intracellular form (multiply in phagocytic vacuoles called morulae)
Transmitted by lone star tick that requires white-tailed deer for growth cycle.
Disease from a tick bite.
Causes HME: Human Monocytic Erlichiosis
Infects circulating leukocytes, lymphocytes, platelets and erythrocytes.
Often fatal in infects immunocompromised such as elderly.
Early symptoms are headache, myalgia and vomiting
Transmitted by Deer ticks and Ixodes Pacificum ticks.
Closely related to Erlichia species.
Causes human granulocyte anaplasmosis or erlichiosis (HGE) which is not usually fatal.
Infects circulating granulocytes (neutrophils and eosinophils)
Extracellular in environment but intracellular in multiplication in mammals.
Survives phagocytosis and lives intracellular.
Tularemia is rabbit fever and is highly infectious.
Transmitted by every route: bug bites, cuts, rubbing in eyes, ingestion, inhalation of feces.
Symptoms: a papule forms at site of infection following a one week incubation period. Draining lymph nodes become very infected and necrotic and drain for weeks as well as fever, malaise, headache and pain.
Diseases are named after location:
Pneumonic: lung (potential bioterrorism agent)
Diagnosis: not grown in culture-highly infectious in lab. Serology Agglutination tests where you compare concentrations 2 weeks apart.
Treatment: streptomycin, gentamicin
Prevention: avoid infected animals and humans
BSL-1: open benches
no regulations (non-infectious E. coli)
BSL-2: limited access lab, advanced training and all clinical samples until identified
BSL-3: biosafety cabinet only, limited access, inward airflow lab
(Brucella, Francisella, Yersinia pestis - potentially lethal agents)
BSL-4: Showers at entry/exit, decontamination of all materials, requires full suits.
(ebola-fatal disease and no vaccines)
Lives in lakes, streams, reservoirs.
Multiplies in free-living ameobae.
Survives in warm, moist areas and is acquired from contaminated water sources/appears to exist in a biofilm layer.
Symptoms: similar to flu, but causes life-threatening pneumonia.
Risk factors: Smoking, immunosuppression, diabetes mellitus,
Diagnosis: direct fluorescent antibody test MALDI-TOF
Treatment: Mecrolides and Quilinolones
Prevention: Proper water treatment and regular filter replacement cooling systems transmission
Obligate intracellular bacteria.
Infect mucosal epithelium (genital, ocular or respiratory)
Forms: EB (inert) and RB (metabolically active)
Lack TCA cycle so they obtain ATP from host cell.
Virulence Mechanisms: Type III secretion system that inject bacterial proteins into host cells (TARP). Downregulate MHC I presentation.
Causative lymphogranuloma venereum (LGV)
Genital infections are asymptomatic and underreported
Clinical manifestations: mucosal inflammation, chronic or recurrent pelvic inflammatory disease, urethritis, cervicitis, ectopic pregnancies, infertility and chronic pelvic pain
Infants born by an infected mother have a chance of inclusion conjunctivitis and severe pneumonia
Detection: Nucleic Acid Amplification tests from void urine and genital swabs. The same test also detects N. gonorrhea
Chronic keratoconjunctivits or granular conjunctivitis
Eyes become infected by rubbing or by flies. Blindness takes years to develop.
Hand washing prevents transmission.
Treatment: Mass treatment of endemic villages with azithromycin but accelerated disease requires surgery
Gram (-) obligate intracellular organism
EB: elementary body which is metabolically inert and infectious
RB: reticulate body that is the intracellular form and is not infectious
TARP:( translocated actin-recruitment protein) injection of TARP into host cell recruits host proteins (actin polymerization complex) for the reuptake of EB.
Causes pneumonitis, pharyngitis, sinusitis, bronchitis and otitis media.
Asymptomatic infection common.
A small number of bacteria can establish infections with a very slow onset of chronic disease.
Causes psittacosis, a lung infection acquired through contact with birds.
Symptoms are malaise, sore throat, photophobia and headaches that precedes pneumonitis
Diagnosis: crackling sounds when listening to lungs and serology.
Treatment: Same as other chlamydia
Prevention: avoid infected birds
Gram (-) spirochete, motile, microaerophilic, silver stained spirals
Virulence: hyaluronidase that breaks down tissue that aids in dissemination
Diagnosis: T. pallidum does not grow in culture. Treponemal Particle Agglutination is for early detection where antibodies interact with antigen-coated particles.
Nontreponemal test are low cost, detect cardiolipin and are only used for late syphilis
Prevention: abstinence, barrier contraception
Primary syphilis: hard chancre on genital mucosal surface that leaks highly infectious fluid that spontaneously heals in 2 weeks
Secondary syphilis: Very Infectious rash, hepatitis, nephritis, alopecia, syphilids
Tertiary syphilis: Not infectious, follows long latency periods of up to 15 years, causes depression, mania or dementia, tabesis, destruction of joints, gummata
Gram (-), diplococcic, non-motile, kidney shaped
Pili attach and add to phagolysosome resistance and complement resistance.
Lipooligosaccharide instead of Lipopolysaccharide that has a shorter O-antigen chains
Causes genital infections: urethritis with yellow pus discharge (men) and endocervitis (women) fallopian tube inflammation
Development of bacteremia leads to skin lesions, arthritis and endocarditis.
Capsule (-), no vaccines
Infection is not protective because of the antigenic variation
Detection: gram stain morphology indicative and Rapid NAAT test confirms
Antibiotic resistance a major concern
Eye infections in newborns that become infected through infected genital tract.
Topical tetracycline or erythromycin ointment is put in eyes of all newborns in the US.
Transmission: respiratory droplets
Virulence factors: Pili that adhere to cells, LPS endotoxin is made at very high levels and is dangerous in blood.
Penetration in epithelium results in sore throat
Septicemia is from endotoxin that damages blood vessels and leads to petechial lesions and damage to organ tissues
Shock occurs from the endotoxin
Fulminating meningococcemia is very severe and leads to high fatality rate if untreated.
Spinal meningitis symptoms are headache, stiff neck and vomiting.
Treatment; Penicillin G (resistant to sulfonamides)
Immunity: complement and antibodies initiate opsonization which initiates phagocytosis and clearance by innate immune cells.
Detection by blood and spinal fluids grown in culture
Vaccines: Menumone (polysaccharide vaccine), Menactra (polysaccharide vaccine + diphtheria toxoid that produced cell-mediated immunity)
Either Bacillus or Clostridium
Clostridium are sensitive to oxygen because they cannot degrade ROS generated in aerobic metabolism
Both are common in soil microbes found worldwide.
Humans are an accidental host.
Both make endospores under unfavorable conditions
Large, motile anaerobic rods that form spores found in soil and feces.
Diseases are mostly caused by secretion of toxins.
Major cause of hospital-associated infection.
Can become major species in gut because of antibiotic use.
Pseudomembranous colitis: toxins (A binds brush border that causes diarrhea, B is a cytotoxin that causes diarrhea) released by bacteria damage mucosal epithelium
Symptoms: watery diarrhea, fever, loss of appetite, nausea, bell pain
Treatment; stop diarrhea-inducing antibiotics and use antibiotics that kill C. difficile or fecal transplants from healthy individuals
Detection: toxin assays and NAATs
Causes gas gangrene which is an infection of soft-tissue wounds from war or illegal abortions.
Alpha-toxin: hemolytic, necrotic, cleaves host cell lipids and inserts in eukaryotic cell membrane.
Symptoms: rapid necrosis, foul-smelling discharge, fever, toxemia, shock, death
Treatment: amputation and Penicillin G
Food Poisoning: caused by warm, infected meat
Spores from soil contaminate fruit and vegetables.
Treatment: antitoxin made in horses.
Needs anaerobic environment for growth.
Infant botulism: from spores in honey in GI tract
Detection: stool sample injected into mice to confirm development and ELISA and PCR
Botulinum block acetylcholine release
Causes Tetanus that is from the release of tetanospasmium neurotoxins (block ACH through SNARE cleavage)
Causes contraction of involuntary muscles that leads to muscle paralysis, airway obstruction and lockjaw.
Toxin in bloodstream is fatal.
Treatment: early antitoxin or toxoid and antibiotics.
Vaccine included in DTaP and TDaP
(required for TSS and scarlet fever)
A. Invasive diseases:
B. Local infections:
C. Post-streptococcal Diseases:
Capsular polysaccharide: prevents phagocytosis and anti-capsular antibodies are protective.
Diseases: pneumonitis, sinusitis, otitis, bronchitis, bacteremia, meningitis
Risk factors: respiratory infections, alcohol/drug use, poor circulatory systems and immunodeficiencies.
Pathology: infections increase fluid in and around lungs.
Immediate treatment with Penicillin G or tetracycline.
Vaccines: for health/lab workds, immunocompromised, smokers, critically ill.
Group B Strep
normal flora of vagina and lower GI tract
In newborns, causes sepsis, meningitis and respiratory distress syndrome.
Pregnant women are tested at 35-37 weeks; IV ampicillin given to mother prevents transmission during labor
Immunocompromised/elderly at risk for invasive diseases: bacteremia, skin/respiratory infections, GI infections
Viridans are prevalent bacteria in upper respiratory tract and important for mucous membrane health.
Normal flora in mouth that are associated with dental cavities that lead to colonization on tooth surfaces, plaque formation and demineralization of tooth enamel.
Can cause endocarditis when they gain access to the bloodstream and bind to heart valves.
Grape-like clusters that grow on most media.
Resistant to high salt concentration, heat and antibiotics.
High carrier rate in population makes it difficult to eradicate
Golden-color carotenoid pigment that is hemolytic and causes skin infections in healthy individuals that spreads by pus-filled lesions or acne.
Scalded-skin syndrome: in infants
Bacteremia and meningitis can come from contaminated surgery or device implants
Causes fatal enterotoxin-based food poisoning
MRSA: often contracted in hospitals
Virulence: Capsular polysaccharide, PG-teichoic acid complex, Catalase (breaks down H202), Coagulase, (clots blood and coats bacteria with fibrin and prevents phagocytosis) hyaluronidase, and staphylokinase
TSS is superantigen as well as enterotoxins A-V
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