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E. Coli |
-Gram negative rod
-Lactose fermenting
-Human colon
-P: More likely to ascend and cause pyelonephritis
-Endotoxin: triggers shock inflammation ant blood brainbarrier
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-Neonatal meningitis
-Second most common source of diarrhea in babies second to rotavirus
ETEC:
-Enterotoxigenic or travelers. Major cause of diarrhea in less than 3 year olds. Produces heat labile toxin and stimulates adenlate cyclase by ADP ribosylation of Gs protein. Produces watery diarrhea. The heat labile toxin causes diarrhea by stimulating guanylate cyclase. Capsule inuibits phagocytosis.
Colonizing factor adhesions bind to small intestine
EPEC:
-Enteropathogenic. Second most common cause of diarrhea in infants after rotavirus. Prolonged, watery diarrhea in babies. Plasmid containing virulence genes
EIEC:
-Enteroinvasive. Invades the large bowel, similar to shigellosis. Often manifests as watery diarrhea with fever and abdominal pain
EHEC:
-Enterohemorrhafic. Ranges from mild diarrhea to hemorrhagic diarrhea. Causes HUS with fever generally absent. HUS most common in kids <5. Plasmidassociated verotoxins. Has a shigalike toxin 1 and 2. INHIBITS PROTEIN SYNTHESIS. Antibiotics may increase risk of HUS
EaggEC:
-EnteroaggregativeE. Coli. Important cause of persistent diarrhea. Low grade fever in developing countries. Also produces enterotixin.
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Pseudomaonas |
-Gram negative rod
-Osidase positive
-Non fermenting
-Slime layer
-Reservoir: ubiquitous in water
-Transmission via raw vegetables and flowes, water aerosols
PATHOGENESIS:
-Endotoxin causes inflammation in tissues and gram negative shock
-Pseudomonas endotoxin ADP ribosylates EF 2 and inhibits protein syntheisis
-Liver is the primary target
COMPROMISING CONIDITONS:
-Transient GI tract colonization in10% in normal pts
-Hot tub folliculitis in normal pts
-Eye ulcers: trauma, coma, prolonged contacts
RESISTANCE:
-common. This bacteria has plasma mediated beta lactamases and acetylating enzymes.
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BURN PATIENTS:
-GI tract colonization skin colonization of eschar cellulitis leading to septicemia
NEUTROPENIC PATIENTS:
-Causes pneumonia and septicemia
-Often superinfection due to braod spectrum antibiotic therapy in IC patients
CHRONIC GRANULOMATOUS DISEASE:
-Pneumonias, septicemias
TREATMENT:
-Antipseudomonal penicillins
-No flowers or raw vegetables in burn units
-Catheter care to prevent pseudomonal UTI and subsequent septicemia
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Legionella |
-Weakly gram negative
-Pleiomorphic rods requiring cysteine and iron
-Water organisms
-Stain poorly with standard gram stain
-Cultured on charcoal yeast extract
-Reservoirs include rivers/streams/amoeba
TRANSMISSION:
-Aerosols from contaminated air conditioning
-No human to human transmission
PREDISPOSING FACTORS:
-Smokers over 55 with ETOH intake
-Immunosuppressed patients (renal transplant)
-PATHOGENESIS:
-Endotoxin
-Intracellular parasite
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LEGIONAIRRE’s DISEASE
-Atypicall pneumonia
-Mental confusion
-Diarrhea (no legionella in gastrointestinal tract)
PONTIAC FEVER
-Pneomonitis, no fatalities, milder from
TREATMENT:
-Fluoroquinolone or azithromycin
-Drugs must penetrate human cells
PREVENTION:
-Routine decontamination of air conditioner cooling tanks
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Bordetella |
-Small gram negative rod
-Fastidious and delicate: cultured on Regan-Lowe
-DFA from NP smear is diagnostic
-PCR and serologies are avialiable for ddx
-Mucosal surface pathogen
-Humans as reservoir; transmitted via droplet
PATHOGENESIS:
-Filamentous hemagluttinin
-Pertussis toxin on outer membrane
-Adenylate cyclase toxin which impairs chemotaxis
-Tracheal cytotoxin which interferes with ciliated action
PERTUSSIS TOXIN::
-ADP ribosylation of Gi (inhibition of negative regulator of adenylate cyclase) interferes with cell to cell signaling
-Lymphocyte promotion
-Histamin sensitivity
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WHOOPING COUGH:
-Three stages after a 7-10 day incubation
-Catarrhal (1-2 week stage): rhinorrhea, malaise, fever, sneezing
-Paroxysmal: repetitive cough with whoops, vimiting. Anxiea and severity of cough cause neurological damage and eye hemorrhage
-Convalesence (>3 weeks): less cough secondary complications like pneimonia manifest themselves.Seizures, encephalopathy
TREATMENT:
-Hospitalization if less than 6 months of age
-Erythromycin
PREVENTION:
-Vaccine DTAP
-Babies are born with little immunity (IgA) from mother
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