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Gram negative cell wall
Inner membrane
Periplasmic space containing:
- Thin peptidoglycan
Outer membrane (contains LPS)
Outer membrane of gram negatives
Contains:
Lipopolysaccharide (LPS)
Porin proteins
Endotoxin - becomes toxic when released during infections
Lipid portion of gram negative outer membrane contains
Functions as receptors and blocking immune response
Function of outer membrane of gram negatives
Porin proteins
Proteins in the upper layer of the outer membrane of gram negative cells - regulate molecules entering and entering the cell
Aerobic Gram-Negative Bacilli
- Non spore forming
- Found in LI (enteric), respiratory, zoonotic, soil, water
- Most not medically important; some true pathogens, some opportunists
- All have LPS outer membrane - release endotoxin
Pseudomonas and Burkholderia
Aerobic gram negative bacilli - opportunistic pathogens
Brucella and Francisella
Aerobic gram negative bacilli - zoonotic pathogens
Bordetella and Legionella
Aerobic gram negative bacilli - mainly human pathogens
Pseudamonas, Burkholderia, Bordetella, Francisella, Alcaligenes
Gram negative rods - Aerobes that do not ferment carbohydrates
Escherichia, Kleisiella, Citrobacter, Enterobacter
Gram negative rods - Facultative anaerobes that do ferment carbohydrates: Lactose fermenters
Salmonella, Shigella, Proteus, Providencia, Morganella, Hafnia, Edwardsiella, Serratia, Yersinia
Gram negative rods - Facultative anaerobes that do ferment carbohydrates: Oxidase-negative
Haemophilus and Pasteurella
Gram negative rods - Facultative anaerobes that do ferment carbohydrates: Oxidase-positive
Bacteriodes
Gram negative rods - Obligate anaerobe
Pathogenic gram negative bacilli
- Pseudamonas Aeriguinosa
- Bordetellsa pertussis
- Legionella spp.
- Escherichia coli
- Escherichia coli O157:H7
Pseudomonas aeruginosa
Gram-negative bacilli most known for complication of burns, skin rashes, corneal ulcers, meningitis, endocarditis, complication of CF, UTIs
Bordetella pertussis
Gram-negative bacilli most known for whooping cough
Legionella spp.
Gram-negative bacilli most known for pneumonia
Escherichia coli
Gram-negative bacilli most known to cause acute diarrhea and UTIs
Escherichia coli O157:H7
Gram-negative bacilli most known for acute diarrhea, colitis, and Hemolytic uremic syndrome
Salmonella typhi
Gram-negative bacilli most known for septicemia and typhoid fever
Salmonella spp.
Gram-negative bacilli most known to cause acute diarrhea
Shigella spp.
Gram-negative bacilli most known to cause neuron damage, acute diarrhea and bacillary dysentery
Yersinia pestis
Gram-negative bacilli most known to cause the Bubonic plague, and pneumonic plague
Plague!!
Haemophilus
Blood-loving Bacilli
- Gram negative pleomorphic rods
- Fastidious (sensitive to drying, temp extremes and disinfectants)
- Grows on chocolate agar ** (needs special techniques to grow on blood agar)
Haemophilus influenzae (H. influenzae)
Gram negative coccobacillus most known for bacterial meningitis, bacteremia, and pneumonia; less serious infections - conjunctivitis, epiglottitis, cellulitis, sinusitis, otitis media, and infectious arthritis
Vaccination against the b serotype
Decreases 90% of disease incidence by H. infuenzae
Meningitis caused by H. influenzae
Fever, vomiting, stiff neck and neurological impairment are symptoms of this disease
90% fatality
Fatality rate in untreated cases of H. influenzae
Alcoholism, poor nutrition, cancer or diabetes
Predisposing factors for H. influenzae induced pneumonia
Resemble those of pneumococcal pneumonia
Symptoms of H. influenzae induced pneumonia resemble those of which infection
Isolation and use of special medial for nutritional requirements
How to diagnose the bacterial cause of pneumonia (H. influenzae)
cephalosporins
Treats pneumonia causes by H. influenzae
Klebsiella
Enterobacteria species that can cause pneumonia
Impaired host defenses
*cause most of the deaths from healthcare associated infections
How would an enterobacteria (Klebsiella) or other gram negative rods cause pneumonia?
Repeated chills, bloody jelly-like sputum, cough, chills, SOB, fever, chest pain, cyanosis
Signs and symptoms of Klebsiella pneumonia
blood-tinged sputum
Symptom of pneumococcal pneumonia that differentiates it from Klebsiella pneumonia
1-3 days
Incubation period of Klebsiella pneumonia
Klebsiella pneumonia
Gram-negative rod with large capsule, produces big mucoid colonies
- Normal microbiota of GI tract and can be found in mouth an throat
Secretions transmitted by contact, or medical equipment (ventilators); Organism colonizes throat ->- travels to lung via inhaled air and mucus --> adhesions aid in colonization
*capsule = virulence factor
How is Klebsiella Pneumonia contracted?
Very old or very young, compromised immune system (alcoholics, hospital pts, institutionalized pts)
Who is typically effected by Klebsiella?
antibiotic/antimicrobial resistance/multi-drug resistance
Strains of bacteria circulating in hospitals, nursing homes often display
Bordetella purtussis
Causative agent of Pertussis; gram-negative rod
cells are inhaled, attached to ciliated cells of respiratory epithelium - colonize upper throat, trachea, bronchi and bronchiole where they release toxins: PT, ACT, TCT)
** Highly contagious
How is Pertussis contracted?
Pertussis toxin (PT)
An A-B endotoxin; B attaches to receptors, A moves through cytoplasmic membrane cAMP; yields increased mucus, decreased killing ability of phagocytes, release of lymphocytes into bloodstream ineffectiveness of natural killer cells
Adenylate cyclase Toxin (ACT)
lyses leukocytes; catalyzes ATP to cAMP
Tracheal cytotoxin (TCT)
causes release of fever-inducing IL-1; toxic to ciliated epithelial cells
whooping cough
Pertussis is also known as
Yes- but still endemic in many countries including U.S.
* Causes half a million deaths annually globally
Is Pertussis preventable by vaccine?
- Highly contagious
- Spread by respiratory secretions/inhaling airborne droplets
- Most infective during catarrhal stage
- Classically fx infants; most fatalities <1yr old
- Mild infxn in older children/adults; may be mistaken for common cold
Hallmarks of pertussis
- Catarrhal stage: Microlide abx (ineffective in paroxysmal stage)
- Intensive support therapy for infants
- DTaP vaccine (Diptheria, Tetanus and acellular pertussis vaccine) + booster (Tdap)
Treatment and prevention of pertussis
Legionella pneumophila; gram- negative rod - facultative intracellular parasite; survives well in warm freshwater containing protozoa (house the bacteria) includes cysts
Legionnaires' disease (type of pneumonia) is caused by which bacteria?
headache, muscle aches, high fever, confusion, shaking chills, dry cough produces sputum, sometimes blood; SOB, GI issues (25% of cases), slow recovery - weakness and fatigue for weeks
Signs and symptoms of Legionnaires' Disease
inhaling aerosolized water with organism - promoted uptake by alveolar macrophages
-Bacteria survive by preventing phagosome-lysosome fusion; multiply within macrophages
-Alvolar cell necrosis and inflammatory response lead to abscesses, pneumonia, pleurisy and bacteremia
-Fatal respiratory failure in 15% of hospitalized cases
*** No direct person-to-person spread
How is Legionaires' contracted?
Yersinia pestis
* Gram negative rod
Which organism is responsible for the plague?
Biofilms in digestive tract of infected fleas - vomit into wounds
How is yersinia pestis spread?
Bubonic plague
Septicemic plague
Pneumonic plague
What does Yersinia pestis cause?
Escherichia coli
Most common aerobic and non-fastidious bacterium in the gut
virulence by plasmid transfer - others are opportunists
How does E. coli spread?
Pathogenic strains of E. coli
- Enterohemorrhagic (EHEC)
- Enterotoxigenic (ETEC)
- Enteroinvasive (EIEC)
- Enteropathogenic (EPEC)
- Enteroaggregrative (EAEC)
- Shigella-toxin (STEC)
Enterohemorrhagic E. coli (EHEC)
Causes hemorrhagic colitis leading to hemolytic uremic syndrome and kidney damage
Enterotoxigenic E. coli (ETEC)
Causes severe diarrhea due to heat-liable toxin and heat-stable toxin - stimulate secretion and fluid loss; also has fimbriae
* cause diarrhea in infants of developing countries, also visitors
* High infectious dose
Enteroinvasive E. coli (EIEC)
Causes inflammatory disease of large intestine
* cause disease in young children in developing countries
Enteropathogenic E. coli (EPEC)
Linked to wasting form of infantile diarrhea
* Greatest cause of mortality among babies
* Protected by antibodies in breast milk
* Low infectious dose
Enteroaggregrative E. coli (EAEC)
Common cause of pediatric diarrhea
* Fx children, travelers, AIDS patients
Shigella toxin E.coli (STEC)
food borne strains; epidemics involving groung beef, unpasteruized milk, bean sprouts
* initial source is often untreated cow manure
* low infectious dose; can also spread by direct contact
Amongst humans
Most clinical cases of E. coli are transmitted how?
~ 70% of traveler's diarrhea
- 50-80% of UTIs
Generally, E. coli causes
- Oral abx - effective in early phases of infection
- OTC tx for sx relief
--- Lorapremide aka Imodium - slows gut motility; but can retain pathogen for longer
--- Bismuth salicylate (pepto-bismol) more effective; counteracts enterotoxin provides an antimicrobic effect
How is E. coli treated?