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Staphylococcus aureus: virulence factors
Site of Infection on skin & Diseases Associated
Protein A (ties up Ig) located on wall, fibronectin-binding protein on wall which promotes adhesion, biofilms (polysaccharides on wall), necrotic enzymes such as hyaluronidase (keeps connective tissue), lipase and protease; DNase (breaks down DNA), hemolysins (phospholipase) which are enzymes breakdown membrane and RBC, toxins such as enterotoxin (food toxemia), exfoliative toxin (cytotoxin of skin), alpha-toxin (aleucocidin) which punch holes in neutrophils, toxic shock syndrome toxin (TSST1) especially for staph aureus which once in the blood causes vasculitis and clumping (IGG) antibody fraction of blood
On skin and forms abscess, carbuncle, impetigo, sties, decubitus ulcer (bed sores), disofuruncles (boils), scalded skin syndrome (SSS)
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Staphylococcus in Intestine: Diseases caused
Enterocolitis often occurs following intensive chemotherapy
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Staphylococcus on hands: Diseases caused
Food poisoning due to heat-stable exotoxin released in high protein foods
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Staphylococcus in bloodstream: Diseases caused and Treatment
- Osteomyelitis (in bone), cellulitis and endocarditis (in valves)
- Treatment: Synthetic penicillin such as methicillin, vancomycin
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Staph in genitourinary tract: Diseases caused and Treatment
- Toxic Shock Syndrome, associated primarily with highly absorbent tampons but various types of surgeries also important
- Treatment: Fluid replacement, drainage of foci of infection, antimicrobial therapy
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Staph epidermidis: Site of Infection
Diseases
Treatment
In nares and on skin, especially axillae, head, legs and arms
Endocarditis, colonization of prostheses, bacteremia from IV catheters
Removal of foreign body or prosthesis, drainage of infection site, antimicrobial therapy such as nafcillin, oxacillin and cephalothin
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Staph saprophyticus: Site of Infection
Diseases
Treatment
Occasionally isolated from skin: but has predilection for urinary tract
Major cause of acute, recurrent cystitis in young women (UTI)
Antimicrobial therapy. Organism is susceptible to most common antimicrobials.
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Streptococcus pyogenes Site of Infection
Virulence Factors
Diseases
In the throat and on skin.
M-protein (Group A) which attaches onto mucus areas, hyaluronic capsule which is antiphagolytic and degrades complement component, protein G (ties up Ig), protein F (epithelial adhesion), hemolysins (S & O) which lyses leukocytes, platelets and erythrocytes, streptokinase which lyses bloodclots to spread throughout body, C5 peptidase which breaks down compliment and creates biofilm, erythrogenic toxins (cytotoxin/superantigens) and causes immunosuppression, and TSSTA (toxic shock syndrome toxin)
May initiate autoimmune diseases (rheumatic fever, glomerulonephritis) as well as scarlet fever and puerperal fever (endometriosis), necrotizing fascritis, pharyngitis, impetigo, erysipelas
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Streptococcus agalactiae: Site of Infection
Diseases Caused
Female Genital Tract
Neonatal Sepsis and meningitis
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Enterococcus faecalis: Site of Infection
Diseases Caused
Colon
Abdominal abscess, urinary tract infection, endocarditis
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Streptococcus bovis: Site of Infection
Diseases Caused
Colon
Endocarditis, Colon Cancer
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Streptococcus anginosus (equi): Site of Infection
Diseases Caused
Throat, colon, female genital tract
Pyogenic infections, phary including brain abscesses
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Viridans streptococci: Site of Infection
Diseases Caused
Mouth, throat, colon, female genital tract
Dental caries (s. mutans), endocarditis, abscesses
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Streptococcus pneumoniae: Site of Infection
Diseases Caused
Throat
Pneumonia, meningitis, endocarditis
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E. coli Enterotoxigenic (ETEC): Symptoms
Virulence Factors
Transmission Site
First of toxic variety, major causes of infant diarrhea and travelers' diarrhea, abdominal cramps, low-grade fever
Heat Labile (LT) sensitive protein to heat stable (ST) enterotoxin lipid, LT resembles cholera toxin in chemistry and action, fimbrial adhesion called colonization factor (CFA)
Ingestion of contaminated food (raw vegetables, fish, meat) or water. Colonizes proximal small intestine.
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E. coli Enteropathogenic (EPEC): Symptoms
Virulance Factors
Transmission Site
First evolution of bacteria, infant diarrhea, fever, vomiting, dirrhea with large amounts of mucus, distinctive lesions in which microvilli are destroyed (fimbraie attaches to receptors)
Cytotoxin similar to Shiga toxin
Ingestion of contaminated food or water, Invades Proximal intestine
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E. coli Enteroinvasive (EIEC): Symptoms
Virulence Factors
Transmission Site
Diarrhea in adults and infants, Resembles shigella in pathogenicity, causes epithelial call death, fever, severe abdominal cramps, gross dysentery with bloody stool and mucus
Several outer membrane proteins, similar to shigella, involved in invasiveness, shiga-like toxin produced
Ingestion of contaminated food or water, predilection for mucosa of the colon
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E. coli Enterohemorrhagic (EHEC): Symptoms
Virulence Factors
Site of Infection
Present day strain, ID50=50, 0157:H7, no fever or fecal leukocytes which distinguishes it from dysentery due to shigella, a hemolytic uremic syndrome may also appear to be characterized by hemolytic anemia and renal failure, cattle may serve as reservoir, also causes stroke and seizures
Potent toxins called Verotoxin or Shiga-like toxins that are related to Shiga toxin
Ingestion of contaminated food or water. Person to person transmission as in nursing homes, during epidemic disease, in large intestine
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E. coli Enteroaggregative (EAEC): Symptoms
Virulence Factors
Site of Infection
evolved strain, 0104:H4, has antibiotic resistance, new STEC (with Shiga toxin), found in sprouts in Germany, Infant diarrhea, traveler's diarrhea, persistent watery diarrhea with vomiting, dehydration and low-grade fever
Plasmid mediated aggregative adherence (intimin) of rods with shortening microvilli, mononuclear infiltration and hemorrhage; decreased fluid absorption
in small intestine, not very toxic
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Salmonella enterica: Symptoms
Virulence Factors
Site of Infection
Diarrhea, enteric fever, typhoid fever, fever, malaise, headache, constipation, bradycardia, and myalgia, enlarged spleen and liver, rose spots usually on skin of chest or abdomen
Type III secretion (sips), epithelial cell invasion (CDT), survival in macrophages (Oxy R), proteins propel from cell to cell, carcinogen causes cancer
Ingested, link up to receptors in intestine, taken into cell by SIPS, causes systemic infection (septicemia)
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Shigella: Symptoms
Virulence Factors
Site of Infection
necrosis of the mucous membrane, superficial ulceration, bleeding
Type III secretion Ipa protein- changes actin fibers, intracellular spread, induction of macrophage apoptosis, shiga toxin, exotoxin inhibits sugar and amino acid absorption in small intestine
Gastrointestinal tract, bloodstream invasion is quite rare, infected dose is 10 to the 3 organisms, highly communicable
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Vibrio cholerae: Symptoms
Virulence Factors
Site of Infection
Diarrhea, dehydration, shock
Attach to microvilli of the brush border of epithelial cells. There they multiply and liberate cholera toxin and perhaps mucinases and endotoxin. Activation of subunit A yields increased levels of intracellular cyclic AMP and results in prolonged hypersecretion of water and electrolytes. Absorption of sodium and chloride is inhibited.
In the intestinal tract O group I cause classical cholera.
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Gram negative coccobacillary- Hemophilus influenzae (Hemophilus egypticus) type b incapsulating: Disease Caused
Virulence Factors
Site of Infection
Treatment
Meningitis in children under 4 years, otitis media in children
Endotoxin (lipid A), capsule(polyribitol phosphate), IgA protease, Cytolethal toxin (CDT) (carcinogen), fimbraie and adhesion
Inhalation of respiratory droplets from active cases or carriers
Ampicillin, chloramphenic or ampicillin
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Gram negative coccobacillary- Hemophilus influenzae noncapsulated: Disease Caused
Virulence Factors
Site of Infection
Treatment
Otitis media in children, pneumonia in elderly
Unknown
Inhalation of respiratory droplets, mother to newborn
Same as H. influenzae
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Gram negative coccobacillary- Hemophilus ducreyi: Disease Caused
Virulence Factors
Site of Infection
Chancroid in men
polymicrobial causes ulcers
uncircumsized more susceptible, STD
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Gram negative coccobacillary- Bordetella pertussis and parapertussis: Disease Caused
Virulence Factors
Site of Infection
Treatment
Pertussis (whooping cough), catarrhal stage (cold) and paroxysmal stage (cough)
Dermadecrotic, Filamentous hemagglutinin, pertussis toxin (cAMP exotoxin), adenylate cyclase (fluid in trachea), Tracheal cytotoxin (kills cilia in trachea)
Erythromycin, tetracycline, chlorampheni killed vaccine part of DTP (used now DTaP)
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Gram negative coccobacillary- Brucella abortus (cattle), mentensis (goat) suis (swine): Disease Caused
Virulence Factors
Site of Infection
Treatment
Brucellosis (undulant fever/chronic), hyperhydrosis, swollen nodes (bubo), hepatitis, granuloma (infection in organs), can become chronic if antibiotics don't kick in fast enough
Toxic LPS and capsule
A zoonosis transmitted to humans by consumption of raw milk or its products, contact with products of conception, ingestion of meat from infected animals, aerosols, lesions
Ampicillin, streptomycin, tetracycline, mass testing, slaughter of infected cattle and vaccination of heifers
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Gram negative coccobacillary- Francisella tularensis: Disease Caused
Virulence Factors
Site of Infection
Treatment
Tularemia (rabbit fever), lawn mower fever
Unknown, Lipid capsule, ulcerating papule at surface, necrotic buboes
Direct contact with infected animals by handling or ingesting contaminated meat, bite of insect vector, inhalation of contaminated aerosols generated by infected animals, rabbits
Streptomycin
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Gram positive coccobacillary- Anthrax(bacillus anthracis) encapsulated : Disease Caused
Virulence Factors
Site of Infection
Cutaneous anthrax is most common, localized itching, a papular lesion forms and turns into black eschar in seven to ten days. Gastrointestinal anthrax causes nausea, vomiting, anorexia, fever, bloody diarrhea, bloody vomit and abdominal pain. Inhalation anthrax is the deadliest
Protein capsule, 3 toxins PA, EF, LF that work together. edema factor and letha factor travel internally via endocytosis and PA punch holes in wall, anthrax toxin produced during sporulation
skin and hides of infected animals, fomites
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Yersinia pestis (bubonic plague): Diseases caused
Virulence factors
Site of Infection
Intense hemorrhagic inflammation develops in the enlarged lymph nodes, which may undergo necrosis and become fluctuant. Can reach bloodstream and become widely disseminated. Hemorrhagic and necrotic lesions may develop in all organs, meningitis and pneumonia
Fra in capsule (antiphagocytic), V & W factors (exotoxins)- shut down TNF (tumono necrosis factor) which is communication in immune system, Coagulase, Pla protease (degrades C3), siderophores, Type III secretion that disrupts actin & proteins of phagocytosis and induce apoptosis in macrophage (Yop gene products), virulence plasmids (has capsule, other Pla, third has LCrV which induces IL 10 and binds TLR2 to downregulate immunity)
reservoirs, vector
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Spirochetes Treponema pallidum: Disease caused
Virulence Factor
Transmission
Treatment
Syphilis: Primary stage: chancre. Goes into latency for a month or so. Secondary Stage: rash and mucous membrane. Goes into latency for 6 moths to 8 years. Tertiary stage: lesions called gummas. Gongenital: stillbirth, abortion, or secondary syphilis.
Do not go deep into tissue, Hyaluronidase allows them to travel deep into the tissue, adhesions, and fibronectin.
Sexual contact, accidental contact with lesions and congenital transfer
Penicillin, tetracycline or erythromycin.
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Spirochetes Treponema pertenue: Disease caused
Virulence Factor
Transmission
Treatment:
Yaws: Primary and secondary skin lesions
First of treponema that infect cell
contact with eating and drinking utensils
Penicillin, improve hygiene
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Spirochetes Treponema carateum: Disease caused
Virulence Factor
Transmission
Treatment
Pinta: Skin lesions, hyperpigmented
In humans ages ago
Contact with eating and drinking utensils
Penicillin, improve hygiene
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Spirochetes Borrelia recurrentis, hermsii, turicatae, parkeri: Disease caused
Haplotype
Transmission
Treatment
Relapsing fever: Bloodstream infected- followed by invasion of kidney, liver, eye, brain. Episodes of fever caused by antigenic variation of borrelia
HLA-DR4 more severe
Horsefly, spider, reservoirs are field mice
Tetracyclines, chloramphenicol, avoid tick-infested areas
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Spirochetes Borrelia burgdorferi: Disease caused
Transmission
Treatment
Lyme disease: Skin lesions in first stage, second and third stages: Arthritis, neurologic and cardiac symptoms, alzheimers, palsy, encephalitis
Ixodid ticks
Oral phenoxymethyl penicillin or tetracyline for first stage, Penicillin G, chloramphenicol, or ceftriaxone for second stage.
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Spirochetes Liptospira interrogans: Disease caused
Transmission
Treatment
Infectious jaundice: Bloodstream invaded- followed by liver, kidney, lung and meninges
Found in warm areas, Ingestion of water contaminated by urinating animals
Penicillin, streptomycin, tetracycline
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Spirochetes Spirillum minor: Disease caused
Transmission
Treatment
Rat-bite fever: Formation of ulcer at site of bite plus body rash
Bite of infected animal such as cat
Self-limiting, but penicillin treatment of complications occur
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Spirochetes Campylobacter jejuni: Disease caused
Haplotypes
Virulence Factor
Transmission
Treatment
Diarrhea
HLA-B27 more severe
Produces enterotoxin similar to LT of E. coli, also possesses adhesion and cytotoxin
Ingestion of contaminated food or water, unpasteurized milk
Erythromycin used in prolonged illness
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Spirochetes Helicobacter pylori: Disease caused
Virulence Factor
Transmission
Treatment
Possible gastritis and stomach or duodenal ulcers; stomach cancer
Urease neutralizes stomach acid; mucinase disrupts lining; CDT toxin necrotizes (fragments DNA)
Human (parents)
Bismuth subsalicylate with amoxicillin or tinidazole
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Anaerobes Clostridium botulinum: Disease caused
Virulence Factor
Transmission
Treatment
Prevents release of acetylcholine from nerve endings/botulism
200 molecules to shut down lung, neurotoxin
potatoes, spinach, beans
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Anaerobes Clostridium tetani: Disease caused
Virulence Factor
prevents release of inhibitory mediators of spinal cord motor neurons/tetanus (e.g. GABA), (Tetanospasmin)- both muscles contract (lockjaw)
Neurotoxin
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Anaerobes Clostridium perfringens major: Disease caused
Virulence Factor
Phospholipase C/gas gengrene (myonecrosis), Necrotic enteritis/ enterotoxemia, increase permeability of intestine, and ADP-ribosylation
Debribin- cut away tissue
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Anaerobes Clostridium difficile: Disease caused
Virulence Factor
antibiotic associated pseudomembranous Colitis- destroys tissue and lining in intestine, and brought on by inbalance in microflora
Enterotoxin- altered membrane permeability, Toxin A
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